Site U1562

Anne Briais, Ross E. Parnell-Turner, Leah J. Levay, Ying Cui, Anita Di Chiara, Justin P Dodd, Tom Dunkley Jones, Deepa Dwyer, Deborah E Eason, Sarah A Friedman, et al.

► To cite this version:

Anne Briais, Ross E. Parnell-Turner, Leah J. Levay, Ying Cui, Anita Di Chiara, et al. Site U1562. Reykjanes Mantle Convection and Climate, 395, International Ocean Discovery Program, 2025, Proceedings of the International Ocean Discovery Program, 978-1-954252-88-2. 10.14379/iodp.proc.395.105.2025. hal-05407492

HAL Id: hal-05407492

https://hal.science/hal-05407492v1

Submitted on 9 Dec 2025

**HAL** is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_2.png" /></figure>

<figure><img src="image_3.png" /></figure>

<figure><img src="image_4.png" /></figure>

# Site U1562¹

## Contents

1 Background and objectives

3 Operations

7 Lithostratigraphy

15 Igneous petrology

21 Alteration petrology and structural geology

28 Micropaleontology

34 Physical properties

39 Stratigraphic correlation

42 Paleomagnetism

48 Geochemistry and microbiology

50 Downhole measurements

57 Age model

59 References

## Keywords

International Ocean Discovery Program, IODP, JOIDES Resolution, Expedition 395, Expedition 384, Expedition 395C, Reykjanes Mantle Convection and Climate, Earth Connections, Earth in Motion, Site U1562, contourite drifts, mantle plume, hydrothermal alteration, oceanic gateways, climate record, Northern Hemisphere glaciation

## Core descriptions

## Supplementary material

## References (RIS)

MS 395-105

Published 21 January 2025

Funded by NSF OCE1326927, ECORD, and JAMSTEC

A. Briais, R.E. Parnell-Turner, L.J. LeVay, Y. Cui, A. Di Chiara, J.P. Dodd, T. Dunkley Jones, D. Dwyer, D.E. Eason, S.A. Friedman, S.R. Hemming, K. Hochmuth, H. Ibrahim, C. Jasper, B.T. Karatsolis, S. Lee, D.E. LeBlanc, M.R. Lindsay, D.D. McNamara, S.E. Modestou, B. Murton, S. OConnell, G.T. Pasquet, P.N. Pearson, S.P. Qian, Y. Rosenthal, S. Satolli, M. Sinnesael, T. Suzuki, T. Thulasi Doss, N.J. White, T. Wu, A. Yang Yang, V. dos Santos Rocha, C. Pearman, and C.Y. Tian<fnref n="2" />

## 1. Background and objectives

Site U1562 is located on Björn drift, on the eastern flank of the Reykjanes Ridge in the North Atlantic Ocean. It is located ~12 km east of Site U1554 (Figures F1, F2) on a basement high at the eastern edge of the main drift deposit. Site U1562 is located on crustal V-shaped ridge (VSR) 3, which is associated with a high in the free-air gravity anomaly, whereas Site U1554 is located on V-shaped trough (VST) 2b. Site U1562 sits on ocean crust with an age of 13.86 Ma estimated from magnetic anomalies.

Site U1562 is located on Seismic Line JC50-1 (Common Midpoint [CMP] 39920) near the intersection with Seismic Line JC50-C2 (CMP 685) (Figures F2, F3); both lines were obtained in 2010 during RRS James Cook Cruise JC50 (Parnell-Turner et al., 2017). Sediment thickness at Site U1562 was expected to be ~465 m (3.237 s two-way traveltime [TWT]) based on seismic imagery. The sediment section at the site is marked by the pinching out of the Björn drift sedimentary deposit, a thicker section of which was cored at Site U1554. Several disruptions in the sediment succession on the seismic profile suggest the presence of unconformities and possible changes in

<figure><img src="image_5.png" /><figcaption>**Figure F1.** Satellite free-air gravity anomaly map, Expedition 395. Inset: North Atlantic region. Solid line = mid-Atlantic ridge, box = location of main panel.</figcaption></figure>

<footnote n="1">¹Briais, A., Parnell-Turner, R.E., LeVay, L.J., Cui, Y., Di Chiara, A., Dodd, J.P., Dunkley Jones, T., Dwyer, D., Eason, D.E., Friedman, S.A., Hemming, S.R., Hochmuth, K., Ibrahim, H., Jasper, C., Karatsolis, B.T., Lee, S., LeBlanc, D.E., Lindsay, M.R., McNamara, D.D., Modestou, S.E., Murton, B., OConnell, S., Pasquet, G.T., Pearson, P.N., Qian, S.P., Rosenthal, Y., Satolli, S., Sinnesael, M., Suzuki, T., Thulasi Doss, T., White, N.J., Wu, T., Yang Yang, A., dos Santos Rocha, V., Pearman, C., and Tian, C.Y., 2025. Site U1562. In Parnell-Turner, R.E., Briais, A., LeVay, L.J., and the Expedition 395 Scientists, Reykjanes Mantle Convection and Climate. Proceedings of the International Ocean Discovery Program, 395: College Station, TX (International Ocean Discovery Program). https://doi.org/10.14379/iodp.proc.395.105.2025</footnote>

<footnote n="2">²Expedition 395 Scientists’ affiliations.</footnote>
the conditions of sediment deposition and evolution. One target for Site U1562 was to obtain a continuous sedimentary record of Björn drift, which will offer millennial-scale climate records. Another target was to core the basaltic crust at a VSR to provide constraints on mantle melting conditions and hydrothermal alteration of the crust, especially in comparison with basalt from Site U1554 located on a VST. Cores and data from this site will address all three of the primary science objectives: (1) crustal accretion and mantle behavior; (2) ocean circulation, gateways, and sedimentation; and (3) time-dependent hydrothermal alteration of oceanic crust.

The operational objectives for this site were to core the sedimentary section using the advanced piston corer (APC)/extended core barrel (XCB) system to the sediment/basement interface, use the rotary core barrel (RCB) system to core ~130 m into the basement, and use downhole wireline tools to log the borehole.

<figure><img src="image_6.png" /><figcaption>**Figure F2.** Seismic Profile JC50-1 near Sites U1554 and U1562. Modified from Parnell-Turner et al. (2017).</figcaption></figure>

<figure><img src="image_7.png" /><figcaption>**Figure F3.** Bathymetric map, Site U1562. Data from the 2010 JC50 site survey cruise. Numbered dots = CMPs.</figcaption></figure>
## 2. Operations

Site U1562 (60°06.3006'N, 26°30.1044'W) consists of three holes, 395C-U1562A, 395C-U1562B, and 395-U1562C, that extend to 300.4–561.5 m drilling depth below seafloor (DSF) (Table T1).

A total of 144 cores were recovered at Site U1562. These cores collected 792.57 m of sediment and basalt over a cored interval of 876.6 m (90% recovery). The APC system was used to collect 36 cores over a 330.0 m interval with 343.87 m of core recovered (104% recovery). The half-length APC (HLAPC) was deployed for 69 cores and recovered 337.83 m of sediment from a 324.3 m interval (104% recovery). The XCB system was deployed over a 68.6 m interval. The eight XCB cores recovered 37.79 m of sediment and basalt (55% recovery). The RCB system was deployed over a 153.4 m interval with 73.08 m of core recovered (48% recovery). A total of 31 cores were collected with the RCB system. Downhole wireline logging operations using four logging tools took place in Hole U1562B.

The total time spent at Site U1562 was 12.3 days.

<table><caption>**Table T1.** Core summary, Site U1562. H = APC, F = HLAPC, X = XCB, R = RCB. DSF = drilling depth below seafloor, CSF = core depth below seafloor. (Continued on next two pages.) Download table in CSV format.</caption><thead><tr><th colspan="2">Hole U1562A</th><th colspan="2">Hole U1562B</th><th colspan="2">Hole U1562C</th><th rowspan="2">Sections (N)</th><th rowspan="2">Temperature measurement</th><th rowspan="2">Oriented</th><th rowspan="2">Lithology</th></tr><tr><th>Core</th><th>Date</th><th>Top of cored interval depth DSF (m)</th><th>Bottom of cored interval depth DSF (m)</th><th>Interval advanced (m)</th><th>Top of cored interval depth CSF (m)</th><th>Bottom of cored interval depth CSF (m)</th><th>Length of core recovered (m)</th><th>Recovery (%)</th></tr></thead><tbody><tr><td colspan="10"><strong>Expedition 395C</strong></td></tr><tr><td colspan="10">Latitude: 60°6.3030'N</td></tr><tr><td colspan="10">Longitude: 26°30.1245'W</td></tr><tr><td colspan="10">Water depth (mbsl): 2003.4</td></tr><tr><td colspan="10">Time on hole (days): 3.27</td></tr><tr><td colspan="10">Seafloor depth DRF (m): 2014.5</td></tr><tr><td colspan="10">Rig floor to sea level (m): 11.1</td></tr><tr><td colspan="10">Penetration DSF (m): 429.8</td></tr><tr><td colspan="10">Cored interval (m): 429.8</td></tr><tr><td colspan="10">Recovered length (m): 411.04</td></tr><tr><td colspan="10">Recovery (%): 96</td></tr><tr><td colspan="10">Total cores (N): 65</td></tr><tr><td colspan="10"><strong>Expedition 395</strong></td></tr><tr><td colspan="10">Latitude: 60°6.2993'N</td></tr><tr><td colspan="10">Longitude: 26°30.1026'W</td></tr><tr><td colspan="10">Water depth (mbsl): 2003.4</td></tr><tr><td colspan="10">Time on hole (days): 7.18</td></tr><tr><td colspan="10">Seafloor depth DRF (m): 2014.5</td></tr><tr><td colspan="10">Rig floor to sea level (m): 11.1</td></tr><tr><td colspan="10">Penetration DSF (m): 561.5</td></tr><tr><td colspan="10">Cored interval (m): 153.4</td></tr><tr><td colspan="10">Recovered length (m): 73.08</td></tr><tr><td colspan="10">Recovery (%): 48</td></tr><tr><td colspan="10">Total cores (N): 31</td></tr><tr><td colspan="10"><strong>Expedition 395</strong></td></tr><tr><td colspan="10">Latitude: 60°6.3015'N</td></tr><tr><td colspan="10">Longitude: 26°30.0754'W</td></tr><tr><td colspan="10">Water depth (mbsl): 2002.7</td></tr><tr><td colspan="10">Time on hole (days): 1.86</td></tr><tr><td colspan="10">Seafloor depth DRF (m): 2014.2</td></tr><tr><td colspan="10">Rig floor to sea level (m): 11.5</td></tr><tr><td colspan="10">Penetration DSF (m): 300.4</td></tr><tr><td colspan="10">Cored interval (m): 293.4</td></tr><tr><td colspan="10">Recovered length (m): 308.45</td></tr><tr><td colspan="10">Recovery (%): 105</td></tr><tr><td colspan="10">Total cores (N): 48</td></tr></tbody></table><table><thead><tr><th>Core</th><th>Date</th><th>Top of cored interval depth DSF (m)</th><th>Bottom of cored interval depth DSF (m)</th><th>Interval advanced (m)</th><th>Top of cored interval depth CSF (m)</th><th>Bottom of cored interval depth CSF (m)</th><th>Length of core recovered (m)</th><th>Recovery (%)</th><th>Sections (N)</th><th>Temperature measurement</th><th>Oriented</th><th>Lithology</th></tr></thead><tbody><tr><td colspan="13"><strong>395C-U1562A-</strong></td></tr><tr><td>1H</td><td>10 Jul 2021</td><td>2135</td><td>0.0</td><td>2.0</td><td>2.0</td><td>0.0</td><td>2.04</td><td>2.08</td><td>104</td><td>3</td><td>Y</td><td>Sediment</td></tr><tr><td>2H</td><td>10 Jul 2021</td><td>2305</td><td>2.0</td><td>11.5</td><td>9.5</td><td>2.0</td><td>11.09</td><td>9.09</td><td>96</td><td>7</td><td>Y</td><td>Sediment</td></tr><tr><td>3H</td><td>11 Jul 2021</td><td>0055</td><td>11.5</td><td>21.0</td><td>9.5</td><td>11.5</td><td>21.37</td><td>9.87</td><td>104</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>4H</td><td>11 Jul 2021</td><td>0155</td><td>21.0</td><td>30.5</td><td>9.5</td><td>21.0</td><td>31.11</td><td>10.11</td><td>106</td><td>8</td><td>APCT-3</td><td>Sediment</td></tr><tr><td>5H</td><td>11 Jul 2021</td><td>0235</td><td>30.5</td><td>40.0</td><td>9.5</td><td>30.5</td><td>40.46</td><td>9.96</td><td>105</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>6H</td><td>11 Jul 2021</td><td>0320</td><td>40.0</td><td>49.5</td><td>9.5</td><td>40.0</td><td>49.76</td><td>9.76</td><td>103</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>7H</td><td>11 Jul 2021</td><td>0415</td><td>49.5</td><td>59.0</td><td>9.5</td><td>49.5</td><td>59.52</td><td>10.02</td><td>105</td><td>8</td><td>APCT-3</td><td>Sediment</td></tr><tr><td>8H</td><td>11 Jul 2021</td><td>0500</td><td>59.0</td><td>68.5</td><td>9.5</td><td>59.0</td><td>68.91</td><td>9.91</td><td>104</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>9H</td><td>11 Jul 2021</td><td>0545</td><td>68.5</td><td>78.0</td><td>9.5</td><td>68.5</td><td>78.49</td><td>9.99</td><td>105</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>10H</td><td>11 Jul 2021</td><td>0650</td><td>78.0</td><td>87.5</td><td>9.5</td><td>78.0</td><td>88.10</td><td>10.1</td><td>106</td><td>8</td><td>APCT-3</td><td>Sediment</td></tr><tr><td>11H</td><td>11 Jul 2021</td><td>0735</td><td>87.5</td><td>97.0</td><td>9.5</td><td>87.5</td><td>97.38</td><td>9.88</td><td>104</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>12H</td><td>11 Jul 2021</td><td>0820</td><td>97.0</td><td>106.5</td><td>9.5</td><td>97.0</td><td>106.86</td><td>9.86</td><td>104</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>13H</td><td>11 Jul 2021</td><td>0925</td><td>106.5</td><td>116.0</td><td>9.5</td><td>106.5</td><td>116.59</td><td>10.09</td><td>106</td><td>8</td><td>APCT-3</td><td>Sediment</td></tr><tr><td>14H</td><td>11 Jul 2021</td><td>1010</td><td>116.0</td><td>125.5</td><td>9.5</td><td>116.0</td><td>125.63</td><td>9.63</td><td>101</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>15H</td><td>11 Jul 2021</td><td>1120</td><td>125.5</td><td>135.0</td><td>9.5</td><td>125.5</td><td>135.47</td><td>9.97</td><td>105</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>16H</td><td>11 Jul 2021</td><td>1215</td><td>135.0</td><td>144.5</td><td>9.5</td><td>135.0</td><td>144.63</td><td>9.63</td><td>101</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>17H</td><td>11 Jul 2021</td><td>1300</td><td>144.5</td><td>154.0</td><td>9.5</td><td>144.5</td><td>154.51</td><td>10.01</td><td>105</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>18H</td><td>11 Jul 2021</td><td>1400</td><td>154.0</td><td>163.5</td><td>9.5</td><td>154.0</td><td>163.46</td><td>9.46</td><td>100</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>19H</td><td>11 Jul 2021</td><td>1445</td><td>163.5</td><td>173.0</td><td>9.5</td><td>163.5</td><td>173.52</td><td>10.02</td><td>105</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>20H</td><td>11 Jul 2021</td><td>1530</td><td>173.0</td><td>182.5</td><td>9.5</td><td>173.0</td><td>183.02</td><td>10.02</td><td>105</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>21H</td><td>11 Jul 2021</td><td>1655</td><td>182.5</td><td>192.0</td><td>9.5</td><td>182.5</td><td>192.49</td><td>9.99</td><td>105</td><td>8</td><td>Y</td><td>Sediment</td></tr><tr><td>22F</td><td>11 Jul 2021</td><td>2010</td><td>192.0</td><td>196.7</td><td>4.7</td><td>192.0</td><td>196.92</td><td>4.92</td><td>105</td><td>5</td><td>Y</td><td>Sediment</td></tr><tr><td>23F</td><td>11 Jul 2021</td><td>2045</td><td>196.7</td><td>201.4</td><td>4.7</td><td>196.7</td><td>201.56</td><td>4.86</td><td>103</td><td>5</td><td>Y</td><td>Sediment</td></tr><tr><td>24F</td><td>11 Jul 2021</td><td>2125</td><td>201.4</td><td>206.1</td><td>4.7</td><td>201.4</td><td>206.26</td><td>4.86</td><td>103</td><td>5</td><td>Y</td><td>Sediment</td></tr><tr><td>25F</td><td>11 Jul 2021</td><td>2155</td><td>206.1</td><td>210.8</td><td>4.7</td><td>206.1</td><td>211.03</td><td>4.93</td><td>105</td><td>5</td><td>Y</td><td>Sediment</td></tr><tr><td>26F</td><td>11 Jul 2021</td><td>2240</td><td>210.8</td><td>215.5</td><td>4.7</td><td>210.8</td><td>215.73</td><td>4.93</td><td>105</td><td>5</td><td>Y</td><td>Sediment</td></tr><tr><td>27F</td><td>11 Jul 2021</td><td>2320</td><td>215.5</td><td>220.2</td><td>4.7</td><td>215.5</td><td>220.40</td><td>4.90</td><td>104</td><td>5</td><td>Y</td><td>Sediment</td></tr><tr><td>28F</td><td>11 Jul 2021</td><td>2350</td><td>220.2</td><td>224.9</td><td>4.7</td><td>220.2</td><td>224.93</td><td>4.73</td><td>101</td><td>5</td><td>Y</td><td>Sediment</td></tr><tr><td>29F</td><td>12 Jul 2021</td><td>0030</td><td>224.9</td><td>229.6</td><td>4.7</td><td>224.9</td><td>229.86</td><td>4.96</td><td>106</td><td>5</td><td>Y</td><td>Sediment</td></tr></tbody></table>
<table><caption>Table T1 (continued). (Continued on next page.)</caption><thead><tr><th>Core</th><th>Date</th><th>Core on deck time UTC (h)</th><th>Top of cored interval depth DSF (m)</th><th>Bottom of cored interval depth DSF (m)</th><th>Interval advanced (m)</th><th>Top of cored interval depth CSF (m)</th><th>Bottom of cored interval depth CSF (m)</th><th>Length of core recovered (m)</th><th>Recovery (%)</th><th>Sections (N)</th><th>Temperature measurement</th><th>Oriented</th><th>Lithology</th></tr></thead><tbody><tr><td>30F</td><td>12 Jul 2021</td><td>0110</td><td>229.6</td><td>234.3</td><td>4.7</td><td>229.6</td><td>234.51</td><td>4.91</td><td>104</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>31F</td><td>12 Jul 2021</td><td>0200</td><td>234.3</td><td>239.0</td><td>4.7</td><td>234.3</td><td>238.21</td><td>3.91</td><td>83</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>32F</td><td>12 Jul 2021</td><td>0240</td><td>239.0</td><td>243.7</td><td>4.7</td><td>239.0</td><td>243.89</td><td>4.89</td><td>104</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>33F</td><td>12 Jul 2021</td><td>0320</td><td>243.7</td><td>248.4</td><td>4.7</td><td>243.7</td><td>248.55</td><td>4.85</td><td>103</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>34F</td><td>12 Jul 2021</td><td>0400</td><td>248.4</td><td>253.1</td><td>4.7</td><td>248.4</td><td>253.31</td><td>4.91</td><td>104</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>35F</td><td>12 Jul 2021</td><td>0435</td><td>253.1</td><td>257.8</td><td>4.7</td><td>253.1</td><td>257.92</td><td>4.82</td><td>103</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>36F</td><td>12 Jul 2021</td><td>0515</td><td>257.8</td><td>262.5</td><td>4.7</td><td>257.8</td><td>262.75</td><td>4.95</td><td>105</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>37F</td><td>12 Jul 2021</td><td>0555</td><td>262.5</td><td>267.2</td><td>4.7</td><td>262.5</td><td>266.98</td><td>4.48</td><td>95</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>38F</td><td>12 Jul 2021</td><td>0640</td><td>267.2</td><td>271.9</td><td>4.7</td><td>267.2</td><td>271.74</td><td>4.54</td><td>97</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>39F</td><td>12 Jul 2021</td><td>0720</td><td>271.9</td><td>276.6</td><td>4.7</td><td>271.9</td><td>276.36</td><td>4.46</td><td>95</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>40F</td><td>12 Jul 2021</td><td>0755</td><td>276.6</td><td>281.3</td><td>4.7</td><td>276.6</td><td>281.20</td><td>4.60</td><td>98</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>41F</td><td>12 Jul 2021</td><td>0835</td><td>281.3</td><td>286.0</td><td>4.7</td><td>281.3</td><td>286.31</td><td>5.01</td><td>107</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>42F</td><td>12 Jul 2021</td><td>0910</td><td>286.0</td><td>290.7</td><td>4.7</td><td>286.0</td><td>290.97</td><td>4.97</td><td>106</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>43F</td><td>12 Jul 2021</td><td>0945</td><td>290.7</td><td>295.4</td><td>4.7</td><td>290.7</td><td>295.61</td><td>4.91</td><td>104</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>44F</td><td>12 Jul 2021</td><td>1030</td><td>295.4</td><td>300.1</td><td>4.7</td><td>295.4</td><td>300.28</td><td>4.88</td><td>104</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>45F</td><td>12 Jul 2021</td><td>1110</td><td>300.1</td><td>304.8</td><td>4.7</td><td>300.1</td><td>304.81</td><td>4.71</td><td>100</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>46F</td><td>12 Jul 2021</td><td>1200</td><td>304.8</td><td>309.5</td><td>4.7</td><td>304.8</td><td>309.77</td><td>4.97</td><td>106</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>47F</td><td>12 Jul 2021</td><td>1235</td><td>309.5</td><td>314.2</td><td>4.7</td><td>309.5</td><td>314.43</td><td>4.93</td><td>105</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>48F</td><td>12 Jul 2021</td><td>1315</td><td>314.2</td><td>318.9</td><td>4.7</td><td>314.2</td><td>318.96</td><td>4.76</td><td>101</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>49F</td><td>12 Jul 2021</td><td>1355</td><td>318.9</td><td>323.6</td><td>4.7</td><td>318.9</td><td>323.90</td><td>5.00</td><td>106</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>50F</td><td>12 Jul 2021</td><td>1430</td><td>323.6</td><td>328.3</td><td>4.7</td><td>323.6</td><td>328.54</td><td>4.94</td><td>105</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>51F</td><td>12 Jul 2021</td><td>1500</td><td>328.3</td><td>333.0</td><td>4.7</td><td>328.3</td><td>332.89</td><td>4.59</td><td>98</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>52F</td><td>12 Jul 2021</td><td>1545</td><td>333.0</td><td>337.7</td><td>4.7</td><td>333.0</td><td>337.89</td><td>4.89</td><td>104</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>53F</td><td>12 Jul 2021</td><td>1620</td><td>337.7</td><td>342.4</td><td>4.7</td><td>337.7</td><td>342.64</td><td>4.94</td><td>105</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>54F</td><td>12 Jul 2021</td><td>1655</td><td>342.4</td><td>347.1</td><td>4.7</td><td>342.4</td><td>347.42</td><td>5.02</td><td>107</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>55F</td><td>12 Jul 2021</td><td>1735</td><td>347.1</td><td>351.8</td><td>4.7</td><td>347.1</td><td>352.06</td><td>4.96</td><td>106</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>56F</td><td>12 Jul 2021</td><td>1815</td><td>351.8</td><td>356.5</td><td>4.7</td><td>351.8</td><td>356.75</td><td>4.95</td><td>105</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>57F</td><td>12 Jul 2021</td><td>2040</td><td>356.5</td><td>361.2</td><td>4.7</td><td>356.5</td><td>361.46</td><td>4.96</td><td>106</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>58X</td><td>12 Jul 2021</td><td>2220</td><td>361.2</td><td>370.9</td><td>9.7</td><td>361.2</td><td>366.27</td><td>5.07</td><td>52</td><td>5</td><td></td><td></td><td>Sediment</td></tr><tr><td>59X</td><td>12 Jul 2021</td><td>2330</td><td>370.9</td><td>380.6</td><td>9.7</td><td>370.9</td><td>378.98</td><td>8.08</td><td>83</td><td>7</td><td></td><td></td><td>Sediment</td></tr><tr><td>60X</td><td>13 Jul 2021</td><td>0155</td><td>380.6</td><td>390.3</td><td>9.7</td><td>380.6</td><td>383.11</td><td>2.51</td><td>26</td><td>3</td><td></td><td></td><td>Sediment</td></tr><tr><td>61X</td><td>13 Jul 2021</td><td>0405</td><td>390.3</td><td>400.0</td><td>9.7</td><td>390.3</td><td>395.09</td><td>4.79</td><td>49</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>62X</td><td>13 Jul 2021</td><td>0555</td><td>400.0</td><td>409.7</td><td>9.7</td><td>400.0</td><td>404.52</td><td>4.52</td><td>47</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>63X</td><td>13 Jul 2021</td><td>0805</td><td>409.7</td><td>419.4</td><td>9.7</td><td>409.7</td><td>413.32</td><td>3.62</td><td>37</td><td>4</td><td></td><td></td><td>Sediment</td></tr><tr><td>64X</td><td>13 Jul 2021</td><td>1025</td><td>419.4</td><td>429.1</td><td>9.7</td><td>419.4</td><td>427.82</td><td>8.52</td><td>88</td><td>7</td><td></td><td></td><td>Sediment</td></tr><tr><td>65X</td><td>13 Jul 2021</td><td>1250</td><td>429.1</td><td>429.8</td><td>0.7</td><td>429.1</td><td>429.81</td><td>0.68</td><td>97</td><td>1</td><td></td><td></td><td>Basalt</td></tr><tr><td colspan="14">395C-U1562B-<br/>11<br/>2R</td><td>Drilled from 0 to 408.1 DSF (m)</td><td>Sediment</td></tr><tr><td colspan="14">3R</td><td>417.6</td><td>Sediment</td></tr><tr><td colspan="14">4R</td><td>427.1</td><td>Sediment/basalt<br/>interface</td></tr><tr><td colspan="14">5R</td><td>432.1</td><td>Basalt</td></tr><tr><td colspan="14">6R</td><td>436.8</td><td>Basalt</td></tr><tr><td colspan="14">7R</td><td>441.8</td><td>Basalt</td></tr><tr><td colspan="14">8R</td><td>446.5</td><td>Basalt</td></tr><tr><td colspan="14">9R</td><td>451.5</td><td>Basalt</td></tr><tr><td colspan="14">10R</td><td>455.5</td><td>Basalt</td></tr><tr><td colspan="14">11R</td><td>460.5</td><td>Basalt</td></tr><tr><td colspan="14">12R</td><td>470.2</td><td>Basalt</td></tr><tr><td colspan="14">13R</td><td>470.2</td><td>Basalt</td></tr><tr><td colspan="14">14R</td><td>474.2</td><td>Basalt and sediment</td></tr><tr><td colspan="14">15R</td><td>479.2</td><td>Basalt</td></tr><tr><td colspan="14">16R</td><td>483.9</td><td>Basalt</td></tr><tr><td colspan="14">17R</td><td>488.9</td><td>Basalt</td></tr><tr><td colspan="14">18R</td><td>493.6</td><td>Basalt</td></tr><tr><td colspan="14">19R</td><td>498.6</td><td>Basalt</td></tr><tr><td colspan="14">20R</td><td>500.7</td><td>Basalt</td></tr><tr><td colspan="14">21R</td><td>503.3</td><td>Basalt</td></tr><tr><td colspan="14">22R</td><td>508.3</td><td>Basalt</td></tr><tr><td colspan="14">23R</td><td>513.0</td><td>Basalt</td></tr><tr><td colspan="14">24R</td><td>518.0</td><td>Basalt</td></tr><tr><td colspan="14">25R</td><td>522.7</td><td>Basalt</td></tr><tr><td colspan="14">26R</td><td>527.7</td><td>Basalt</td></tr><tr><td colspan="14">27R</td><td>532.4</td><td>Basalt</td></tr><tr><td colspan="14">28R</td><td>537.4</td><td>Basalt</td></tr><tr><td colspan="14">29R</td><td>542.1</td><td>Basalt</td></tr><tr><td colspan="14">395C-U1562B-<br/>11<br/>2R</td><td>Drilled from 0 to 408.1 DSF (m)</td><td>Basalt</td></tr><tr><td colspan="14">3R</td><td>417.6</td><td>Basalt</td></tr><tr><td colspan="14">4R</td><td>427.1</td><td>Basalt</td></tr><tr><td colspan="14">5R</td><td>432.1</td><td>Basalt</td></tr><tr><td colspan="14">6R</td><td>436.8</td><td>Basalt</td></tr><tr><td colspan="14">7R</td><td>441.8</td><td>Basalt</td></tr><tr><td colspan="14">8R</td><td>446.5</td><td>Basalt</td></tr><tr><td colspan="14">9R</td><td>451.5</td><td>Basalt</td></tr><tr><td colspan="14">10R</td><td>455.5</td><td>Basalt</td></tr><tr><td colspan="14">11R</td><td>460.5</td><td>Basalt</td></tr><tr><td colspan="14">12R</td><td>470.2</td><td>Basalt</td></tr><tr><td colspan="14">13R</td><td>470.2</td><td>Basalt</td></tr><tr><td colspan="14">14R</td><td>474.2</td><td>Basalt</td></tr><tr><td colspan="14">15R</td><td>479.2</td><td>Basalt</td></tr><tr><td colspan="14">16R</td><td>483.9</td><td>Basalt</td></tr><tr><td colspan="14">17R</td><td>488.9</td><td>Basalt</td></tr><tr><td colspan="14">18R</td><td>493.6</td><td>Basalt</td></tr><tr><td colspan="14">19R</td><td>498.6</td><td>Basalt</td></tr><tr><td colspan="14">20R</td><td>500.7</td><td>Basalt</td></tr><tr><td colspan="14">21R</td><td>503.3</td><td>Basalt</td></tr><tr><td colspan="14">22R</td><td>508.3</td><td>Basalt</td></tr><tr><td colspan="14">23R</td><td>513.0</td><td>Basalt</td></tr><tr><td colspan="14">24R</td><td>518.0</td><td>Basalt</td></tr><tr><td colspan="14">25R</td><td>522.7</td><td>Basalt</td></tr><tr><td colspan="14">26R</td><td>527.7</td><td>Basalt</td></tr><tr><td colspan="14">27R</td><td>532.4</td><td>Basalt</td></tr><tr><td colspan="14">28R</td><td>537.4</td><td>Basalt</td></tr><tr><td colspan="14">29R</td><td>542.1</td><td>Basalt</td></tr><tr><td colspan="14">395C-U1562B-<br/>11<br/>2R</td><td>Drilled from 0 to 408.1 DSF (m)</td><td>Basalt</td></tr><tr><td colspan="14">3R</td><td>417.6</td><td>Basalt</td></tr><tr><td colspan="14">4R</td><td>427.1</td><td>Basalt</td></tr><tr><td colspan="14">5R</td><td>432.1</td><td>Basalt</td></tr><tr><td colspan="14">6R</td><td>436.8</td><td>Basalt</td></tr><tr><td colspan="14">7R</td><td>441.8</td><td>Basalt</td></tr><tr><td colspan="14">8R</td><td>446.5</td><td>Basalt</td></tr><tr><td colspan="14">9R</td><td>451.5</td><td>Basalt</td></tr><tr><td colspan="14">10R</td><td>455.5</td><td>Basalt</td></tr><tr><td colspan="14">11R</td><td>460.5</td><td>Basalt</td></tr><tr><td colspan="14">12R</td><td>470.2</td><td>Basalt</td></tr><tr><td colspan="14">13R</td><td>470.2</td><td>Basalt</td></tr><tr><td colspan="14">14R</td><td>474.2</td><td>Basalt</td></tr><tr><td colspan="14">15R</td><td>479.2</td><td>Basalt</td></tr><tr><td colspan="14">16R</td><td>483.9</td><td>Basalt</td></tr><tr><td colspan="14">17R</td><td>488.9</td><td>Basalt</td></tr><tr><td colspan="14">18R</td><td>493.6</td><td>Basalt</td></tr><tr><td colspan="14">19R</td><td>498.6</td><td>Basalt</td></tr><tr><td colspan="14">20R</td><td>500.7</td><td>Basalt</td></tr><tr><td colspan="14">21R</td><td>503.3</td><td>Basalt</td></tr><tr><td colspan="14">22R</td><td>508.3</td><td>Basalt</td></tr><tr><td colspan="14">23R</td><td>513.0</td><td>Basalt</td></tr><tr><td colspan="14">24R</td><td>518.0</td><td>Basalt</td></tr><tr><td colspan="14">25R</td><td>522.7</td><td>Basalt</td></tr><tr><td colspan="14">26R</td><td>527.7</td><td>Basalt</td></tr><tr><td colspan="14">27R</td><td>532.4</td><td>Basalt</td></tr><tr><td colspan="14">28R</td><td>537.4</td><td>Basalt</td></tr><tr><td colspan="14">29R</td><td>542.1</td><td>Basalt</td></tr></tbody></table>
**2.1. Expedition 395C**

**2.1.1. Hole U1562A**

The vessel began the 6.1 nmi transit from Hole U1554F to Site U1562 in dynamic positioning (DP) mode on 10 July 2021. The crew continued to pull up the drill pipe following the completion of operations in Hole U1554F during the transit. The end of the pipe cleared the rotary table at 1130 h UTC. At 1306 h on 10 July, the vessel arrived at Site U1562, and the APC/XCB bottom-hole assembly (BHA) was made up. The drill pipe was run to 1996 meters below sea level (mbsl) to take the first APC core.

Hole U1562A (60°06.3030′N, 26°30.1245′W), located 21 m west of the site coordinates, was spud-
ded at 2115 h, and Core 1H recovered the mudline and 2.08 m of core, establishing a seafloor
depth of 2003.4 mbsl. Cores 2H-21H were advanced from 2.0 to 192.0 m DSF using the APC sys-
tem. Core 21H experienced significant overpull and was drilled over with the drill string to release
the core barrel. HLAPC core barrels were made up, and coring continued with Cores 22F-57F
(192.0-361.2 m DSF) with 4.7 m advances. HLAPC refusal was met with Core 57F, which also
required the drill string to drill over the core barrel to release it from the sediment. The XCB core
barrels were made up, and coring continued with Cores 58X-64X (361.2-429.1 m DSF). After cor-
ing Core 64X, the XCB cutting shoe was severely damaged and slightly melted and the base of the
core catcher contained basalt. Another core barrel was deployed, and Core 65X was advanced to
ensure that the bit had reached basement. The bit advanced 0.7 m over 1 h, and Core 65X recov-
ered 0.68 m of basalt, confirming a basement depth of 429.1 m DSF. The final depth of Hole
U1562A was 429.8 m DSF. The drill string was pulled from the hole, with the bit reaching the
seafloor at 1535 h on 13 July. Hole U1562A ended when the bit reached the rotary table at 1935 h.

All APC cores were oriented, and formation temperature measurements using the advanced piston corer temperature (APCT-3) tool were collected for Cores 395C-U1562A-4H, 7H, 10H, and 13H. Samples for interstitial water (IW), microbiology, micropaleontology, and gas analyses were routinely collected on the catwalk.

A total of 411.04 m of core was recovered over a 429.8 m interval (96% recovery). The average recovery for piston cores was 104% with the APC system and 103% with the HLAPC system. The XCB system had an average recovery of 55%.

**2.1.2. Hole U1562B**

Following the end of Hole U1562A, an RCB BHA with a C-4 RCB bit was made up and the drill string was lowered to the seafloor. The ship was offset 21 m east-southeast of Hole U1562A, near the site coordinates, and Hole U1562B (60°6.2993′N, 26°30.1026′W; 2003.4 mbsl) was spudded at 0320 h on 14 July 2021 and advanced without coring to 408.1 m DSF. The center bit was recovered, and an RCB core barrel was deployed. Cores 2R-13R were advanced from 408.1 to 474.2 m DSF, recovering 48.65 m of sediment and basalt (55% recovery). The sediment/basement interface was recovered in Core 4R at 429.0 m DSF. Coring rates drastically sped up from ~2 to over 7 m/h while drilling Core 14R. The driller noted that there was a ~3 m interval that drilled extremely quickly. It was soon revealed that Core 14R recovered 0.6 m of carbonate ooze bracketed by basalt. Coring continued with Cores 15R-19R advancing from 479.2 to 500.7 m DSF (47% recovery). While coring Core 19R, the penetration rate dropped to 1 m/h and there was erratic torque on the bit. It was suspected that the drill bit was damaged, and the rig floor crew began pulling the pipe out of the hole. A free-fall funnel was deployed at 0220 h on 17 July to allow for the reentry of Hole U1562B. The bit cleared the seafloor at 0312 h and the rotary table at 0708 h. The bit was indeed damaged; a new C-7 RCB coring bit was made up to the BHA, and the crew assembled the drill string. The subsea camera was deployed at 1130 h to observe the reentry of Hole U1562B, which occurred at 1450 h. The subsea camera was retrieved, and the drill string advanced to 500.7 m DSF. After cleaning the hole with a high-viscosity mud sweep, Cores 20R-28R advanced from 500.7 to 561.5 m DSF. Coring operations concluded in Hole U1562B after coring 132.5 m into the basement section. The final depth of Hole U1562B was 561.5 m DSF.
A total of 73.08 m of core was recovered over a 153.4 m cored interval in Hole U1562B (48% recovery). In all, 31 RCB cores were collected from this hole. The average rate of penetration while coring the basalt was 2.1 m/h.

Following coring, the rotary shifting tool (RST) was run to release the bit into the bottom of the hole. The drill string was pulled up, and the end of the pipe was set at 89 m DSF. The triple combination (triple combo) tool string was made up and deployed at 1755 h on 19 July. After completing two successful passes of the entire hole, the tools were retrieved and reached the rig floor at 2310 h. After the triple combo tool string was laid out, the Formation MicroScanner (FMS)-sonic tool string was made up and deployed at 0100 h on 20 July. Following two passes that extended to the base of the hole, the FMS-sonic tool string was pulled from the hole and reached the rig floor at 0645 h. The next logging run used the Versatile Seismic Imager (VSI). The protected species observation protocols began at 0730 h, and the International Ocean Discovery Program (IODP) technical staff ramped up the air guns starting at 0834 h. The VSI was lowered to the base of the hole, and a total of four depth stations (420.5, 426, 459.9, and 556.6 m wireline log depth below seafloor [WSF]) were completed, two in the basement section, one at the sediment/basement interface, and one in the lowermost sediment. The VSI could not be successfully run throughout the sedimentary section because of the wide diameter (>16 inches) of the borehole. Following the VSI run, the air guns were put away, and the tool reached the rig floor at 1320 h. The final logging run, using the Ultrasonic Borehole Imager (UBI), began at 1445 h. The UBI made two passes of the basement section, acquiring 360° borehole images. The UBI was recovered at the rig floor at 2130 h. The drill string was pulled out of the hole to ~1489 mbl, and the ship began the transit in DP mode to Hole U1554F at 2355 h on 20 July, ending operations at Site U1562.

## 2.2. Expedition 395

### 2.2.1. Hole U1562C

The vessel returned to Site U1562 on 1 July 2023. With the drill bit ~54 m above the seafloor, the vessel transited in DP mode from Site U1554 to Site U1562. Following a 6.1 nmi transit, the vessel was over the site coordinates at 1210 h, marking the start of Hole U1562C (60°06.3015'N, 26°30.0754'W), which was spudded at 1500 h. The mudline Core 1H recovered 5.37 m, establishing a seafloor depth of 2002.7 mbl. Cores 1H-16H advanced the hole to 139.3 m DSF, and all APC cores were oriented using the Icefield MI-5 core orientation tool. One drilled interval of 1 m (395-U1562C-51) was used to offset coring gaps observed by the stratigraphic correlators.

Core 395-U1562C-16H had 100,000 lb of overpull and required a drill-over to free the core barrel. Refusal of the APC system was reached, and the HLAPC system was deployed for the remainder of the hole. Cores 17F-53F advanced the hole to 300.4 m DSF. Four short drilled intervals (1.5-2 m in length) were used to offset coring gaps between Holes U1562A and U1562C for stratigraphic correlation. After reaching the target depth of 300 m DSF, the drill pipe was pulled from the hole with the bit clearing the seafloor at 0405 h on 3 July. A total of 48 cores were collected in Hole U1562C, recovering 308.45 m of sediment over a 293.4 m cored interval (105% recovery). The BHA was broken down, and the rig was secured for transit. At 0900 h, the ship was switched from DP to cruise mode, ending operations at Site U1562.

## 3. Lithostratigraphy

The sediments at Site U1562 are primarily composed of silty clay with variable amounts of carbonate (Lithostratigraphic Units I–III), underlain by nannofossil ooze transitioning to chalk near the sediment/basement interface (Unit IV). Unit divisions were made based on (1) visual core description, (2) natural gamma radiation (NGR) measurements, (3) smear slide examination, (4) bulk calcium carbonate (CaCO₃) measurements, and (5) L* reflectance (Figures F4, F5; Table T2). To assist understanding the sedimentologic patterns at this site, NGR and reflectance data were smoothed using an eighth-order lowpass Butterworth filter with a cutoff of 0.125 times the Nyquist frequency (Figure F5; this was applied to data that had undergone cleaning; see Physical properties in the Expedition 395 methods chapter [Parnell-Turner et al., 2025a]). This bidirectional linear digital filter avoids phase shift, maintaining correct peak positions (Butterworth,
<figure><img src="image_8.png" /></figure>

**Figure F4.** Lithostratigraphic summary, Site U1562. cps = counts per second. For lithology legend, see Figure F9 in the
Expedition 395 methods chapter (Parnell-Turner et al., 2025a).

<figure><img src="image_9.png" /></figure>

**Figure F5.** Parameters used for lithologic unit definitions, Site U1562. NGR and reflectance (L*): data from Hole U1562A are shown. cps = counts per second, black/gray dots = data with/without Butterworth filter applied.
1930; Lyons, 2011). Immediately below the transition between Units I and II, there are several sharp boundaries noted in the core sections. Unit III is defined by extensive evidence for soft-sediment deformation, possibly due to a series of slumps. There is a sharp contact between Units III and IV. Weight percent CaCO₃ is highly variable, but average values increase downhole (note that CaCO₃ measurements were spaced approximately one to three per 10 m and thus may not fully represent CaCO₃ variability with depth). Small clasts of volcaniclastic material (pumice and scoria) are found throughout the sequence at Site U1562. All clasts larger than 2 cm are listed in Table T3.

## 3.1. Lithostratigraphic Unit I

Intervals: 395C-U1562A-1H, 0 cm, to 16H-1, 0 cm; 395-U1562C-1H-1, 0 cm, to 16H-4, 0 cm

Depths: Hole U1562A = 0–135.0 m core depth below seafloor, Method A (CSF-A); Hole U1562C = 0–135.23 m CSF-A

Thickness: Hole U1562A = 135.0 m; Hole U1562C = 135.23 m

Age: Holocene to early Pliocene

Lithology: silty clay

Unit I is primarily silty clay, most commonly grayish brown, gray, and light brownish gray in Hole U1562A (Figure F6). During Expedition 395, when cores were described soon after recovery, col-

<table><caption>**Table T2.** Lithostratigraphic summary, Site U1562. EOH = end of hole. Download table in CSV format.</caption><thead><tr><th>Lith. unit</th><th>Interval</th><th>Depth CSF-A (m)</th><th>Age</th><th>Main lithologies</th><th>Minor lithologies</th></tr></thead><tbody><tr><td>I</td><td>395C-U1562A-1H, 0 cm, to 16H-1, 0 cm</td><td>0–135.0</td><td>Holocene to early Pliocene</td><td>Silty clay</td><td>Silty clay with biosilica, silty clay with foraminifers, silty clay with sand</td></tr><tr><td>I</td><td>395-U1562C-1H-1, 0 cm, to 16H-4, 0 cm</td><td>0–135.23</td><td>Holocene to early Pliocene</td><td>Silty clay</td><td>Silty clay with biosilica, silty clay with foraminifers, silty clay with sand</td></tr><tr><td>II</td><td>395C-U1562A-16H-1, 0 cm, to 35F-1, 0 cm</td><td>135.0–253.1</td><td>early Pliocene to late Miocene</td><td>Silty clay, silty clay with carbonate</td><td>Silty clay with foraminifers, carbonate silty clay</td></tr><tr><td>II</td><td>395-U1562C-16H-4, 0 cm, to 42F-CC, 22 cm</td><td>135.23–251.49</td><td>early Pliocene to late Miocene</td><td>Silty clay, silty clay with carbonate</td><td>Silty clay with foraminifers, carbonate silty clay</td></tr><tr><td>III</td><td>395C-U1562A-35F-1, 0 cm, to 55F-4, 14 cm</td><td>253.1–351.36</td><td>late Miocene</td><td>Silty clay with carbonate, silty clay</td><td>Carbonate silty clay, carbonate mud</td></tr><tr><td>III</td><td>395-U1562C-44F-1, 0 cm, to EOH</td><td>253.4–300.68</td><td>late Miocene</td><td>Silty clay with carbonate, silty clay</td><td>Carbonate silty clay, carbonate mud</td></tr><tr><td>IV</td><td>395C-U1562A-55F-4, 14 cm, to 64X-CC, 33 cm</td><td>351.36–427.73</td><td>late Miocene</td><td>Nannofossil ooze, nannofossil chalk</td><td>Carbonate silty clay</td></tr><tr><td>IV</td><td>395C-U1562B-2R-1, 3 cm, to 4R-1, 147 cm</td><td>408.13–428.57</td><td>late Miocene</td><td>Nannofossil ooze, nannofossil chalk</td><td>Carbonate silty clay</td></tr></tbody></table>

<table><caption>**Table T3.** Clasts (>2 cm), Site U1562. Download table in CSV format.</caption><thead><tr><th>Core, section, interval (cm)</th><th>Description</th></tr></thead><tbody><tr><td>395C-U1562A-2H-1, 16–16</td><td>2 cm subrounded basalt</td></tr><tr><td>2H-1, 129–129</td><td>3 cm angular conglomerate</td></tr><tr><td>2H-3, 13–13</td><td>2 cm subrounded metasediment</td></tr><tr><td>2H-3, 14–14</td><td>2 cm angular metasediment</td></tr><tr><td>2H-4, 43–43</td><td>5 cm subrounded granite</td></tr><tr><td>2H-5, 49–49</td><td>2 cm angular conglomerate</td></tr><tr><td>14H-1, 86–86</td><td>Fractured, well-rounded soft-sediment clast</td></tr><tr><td>58X-1, 24–32</td><td>6 cm rounded basalt</td></tr><tr><td>58X-1, 24–32</td><td>3 cm rounded micrite</td></tr><tr><td>58X-1, 30–32</td><td>2 cm subangular microgranular dark reddish clast</td></tr><tr><td>59X-1, 0–4</td><td>4 cm amphibolite gneiss clasts</td></tr><tr><td>59X-1, 0–5</td><td>5 cm amphibolite gneiss clasts</td></tr><tr><td>60X-1, 0–5</td><td>4 cm metamorphic, possible gneiss clasts</td></tr><tr><td>61X-1, 0–5</td><td>5 cm angular gneiss</td></tr><tr><td>395-U1562C-3H-2, 8–54</td><td>3 cm granite clast at 15 cm</td></tr><tr><td>4H-3, 5–8</td><td>3 cm drop stone</td></tr><tr><td>14H-3, 117–119</td><td>2 cm basalt</td></tr><tr><td>30F-1, 1–5</td><td>5 cm metavolcanic clast</td></tr><tr><td>36F-1, 7–10</td><td>2 cm clast</td></tr></tbody></table>
ors for these same sediments in Hole U1562C were predominantly very dark gray, olive gray, and brown. The discrepancy in color is likely due to oxidation of the sediments prior to core descrip-
tion for Expedition 395C (core description occurred ~10 months after core recovery). Unit I ex-
hibits relatively high frequency and amplitude variation in NGR values. In contrast, reflectance
(L*) values exhibit little variability throughout this unit. The exception is the upper 30 m of sedi-
ment in which reflectance values are slightly more variable (L*, a*, and b*), coinciding with an in-
terval in which foraminifers and biogenic silica are slightly more abundant and colors are slightly
brighter (yellowish brown, pale brown, and gray; Cores 395C-U1562A-1H through 4H and 395-
U1562C-1H through 4H). Nannofossils and foraminifers are present throughout the unit, al-
though in highly variable amounts, consistent with variable CaCO₃ percent, which ranges from
below ~1 to 83 wt% (average = 16 wt%). Biosilica is present throughout in varying but minor
amounts. With respect to relative abundance within the biosiliceous component, sponge spicules
are present in trace to abundant amounts, radiolarians are present in trace amounts, diatoms are
present in trace to common amounts, and silicoflagellates are present in trace amounts. The ter-
rigenous components are primarily quartz and feldspar. Glass, oxides, and uncommonly glauco-
nite and inorganic calcite are also observed (Figure F6A–F6C). A thin glassy layer is observed in
Section 395-U1562C-7H-5, 47 cm. Several sharp boundaries and graded beds with a fining-up-
ward texture are present in Core 3H. Laminations are observed at the base of Section 12H-4 (128–
148 cm), although these are clearer in X-Ray Linescan Logger (XSCAN) images than macroscopic
observation (Figure F7). The cores of this unit show little drilling disturbance except for some
soupy intervals in the topmost section of cores. Bioturbation is primarily sparse to moderate.

**3.2. Lithostratigraphic Unit II**

Intervals: 395C-U1562A-16H-1, 0 cm, to 35F-1, 0 cm; 395-U1562C-16H-4, 0 cm, to 42F-CC,
22 cm

Depths: Hole U1562A = 135.0–253.1 m CSF-A; Hole U1562C = 135.23–251.49 m CSF-A

Thickness: Hole U1562A = 118.1 m; Hole U1562C = 116.26 m

Age: early Pliocene to late Miocene

Lithology: silty clay, silty clay with carbonate

<figure><img src="image_10.png" /></figure>

**Figure F6.** Unit I and II silty clay, calcite minerals, and sponge spicules, Site U1562. A, B. Silty clay with abundant terrigenous grains (e.g., quartz and feldspar) and traces of biosilica in Unit I in (A) plane-polarized light (PPL) and (B) cross-polarized light (XPL). C. Cluster of inorganic calcite minerals with gypsum plate in Unit I (XPL). D. Silty clay with opaque grains, glass, biosilica, and pyrite infilling of microfossils (radiolarian near bottom center) in Unit II (PPL). E. Silty clay with biosilica and abundant glass in Unit II (PPL). Some grains (lower left) have no vesicles, and others (upper right) have dark vesicles. F. Pyrite infilling of sponge spicule in Unit II (PPL).
Unit II is mainly light brownish gray, dark grayish brown, and grayish brown silty clay and silty clay with carbonate. As for Unit I, during Expedition 395 and for the same sequence of sediments from Hole U1562C, the colors described were more commonly dark or olive gray than brown. Although cycles in NGR values display lower amplitude and frequency in comparison to Unit I, reflectance (L\*) values display higher amplitude variations (Figures F4, F5). CaCO₃ measurements are again variable with depth in this unit, ranging 7–55 wt% (average = 28 wt%). Beds of carbonate silty clay and silty clay with foraminifers (light gray, dark gray, or greenish gray) are found at intermittent depths, including in Cores 395C-U1562A-22F, 32F, and 33F and 395-U1562C-17H, 18H, 19H, 33F, 34F, and 42F. Disseminated pyrite is commonly observed in smear slides in this unit, often infilling siliceous and carbonate microfossils (Figure F6D–F6F). Although present throughout Site U1562, glass is more abundant in smear slides in Unit II than in Unit I (Figure F6A, F6D, F6E).

Several sharp contacts are observed near the interface between Units I and II. These contacts occur at several depths in Cores 395C-U1562A-16H through 18H and 395-U1562C-16H through 21F (Figure F8A–F8H). The most prominent contact in Hole U1562C, located in Section 16H-4A, 102 cm, has a thin (<0.5 cm), bright orange layer that displays abundant iron oxides in smear slide (Figure F8F). Other layers display thin (~1–3 cm) intervals of dark green, very fine grained material (Figure F8E, F8G). Occasional evidence of soft-sediment deformation is present in Sections 18F-2, 18F-3, 20F-2, 20F-3, 26F-1, 26F-2, 28F-2, and 40F-3 (Figure F8I, F8J). Sediment layers with abundant glass are also observed macroscopically (e.g., intervals 395C-U1562A-17H-4, 14–16 cm; 20H-7, 40–45 cm; 21H-1, 95–101 cm; and 395-U1562C-34F-3, 30–35 cm). Diffuse, dark gray blebs or layers that may contain glass are present but were more difficult to assess macroscopically because they do not present as distinct layers; time constraints prohibited shipboard smear slide analysis for all of these features (e.g., intervals 395C-U1562A-18H-6, 14–15 cm, and 21H-4, 42–44 cm). Small pumice and scoria clasts (<2 cm) were observed in Sections 30F-1, 107 cm, and 30F-2, 2, 43, and 102 cm. Bioturbation is generally slight to moderate in this unit. Some drilling disturbance is present, ranging from slight to severe deformation, although this is generally confined to short intervals at or near the tops of core sections.

### 3.3. Lithostratigraphic Unit III

Intervals: 395C-U1562A-35F-1, 0 cm, to 55F-4, 14 cm; 395-U1562C-44F-1, 0 cm, to end of hole

Depths: Hole U1562A = 253.1–351.36 m CSF-A; Hole U1562C = 253.4–300.68 m CSF-A

Thickness: Hole U1562A = 98.26 m; Hole U1562C = 47.28 m

Age: late Miocene

Lithology: silty clay with carbonate, carbonate silty clay

Unit III is predominately silty clay and silty clay with carbonate, with intervals of carbonate silty clay and carbonate mud. This unit is defined by the abundance of features consistent with soft-

<figure><img src="image_11.png" /><figcaption>**Figure F7.** Comparison of laminations at the base of 395-U1562C-12H-4. SHIL = Section Half Imaging Logger.</figcaption></figure>
sediment deformation throughout. Because the sediments are clay rich and homogeneous in appearance and lack well-defined bedding features such as laminae or cross-bedding, the deformation is primarily recognized by color contrasts between soft clasts of silty clay. The features observed include several distinctive layers of centimeter-scale lumps of silty clay resembling brecciated mud clasts, with or without matrix. Where matrix is present, it is of a similar texture to the clasts. The variable coloration of the sediment clasts, with interlocking, irregular blobs in matrix resembles the Camouflage Central-Europe pattern in some cores (e.g., 395C-U1562A-35F, 43F, 49F, 50F, 53F, and 54F) (Figure F9A–F9C). Other expressions of soft-sediment deformation and disorganization, such as convoluted layers, high-angle contacts (often with curvature) between differently colored layers, flow structures, dragging structures, folding, arching, and squeezing are present in the cores listed previously as well as in Cores 37F, 46F, 52F and 395-U1562C-44F, 45F, 49F, 50F, 51F, 52F, and 53F (Figure F9D–F9F). The extensive deformation observed across Unit III, combined with thinner intervals of apparently undisturbed sediment, gives the impression of a thick series of slumps separated by short intervals of quiescence.

CaCO₃ measurements are again highly variable in Unit III, ranging 3–65 wt% (average = 35 wt%), likely reflecting the incorporation of several layers of sediment with different initial depositional conditions into the slumps. Similar to Unit II, Unit III continues to present disseminated pyrite and glass in smear slides. A glass-rich layer is present at the base of a deformed layer in interval 395C-U1562A-37F-2, 66–68 cm. Small scoria clasts are present in Cores 37F, 53F, and 54F. Bioturbation ranges from absent to abundant. Drilling disturbance is minor in this unit; where present, it consists of slightly to moderately soupy or fragmented intervals, generally occurring in the uppermost few centimeters of cores.

<figure><img src="image_12.png" /></figure>

**Figure F8.** Sharp boundaries observed at the top of Unit II, Holes U1562A and U1562C. Close up images of most contacts were not made during Expedition 395C. However, all of the contacts shown in this image can be traced between Holes U1562A and U1562C.
**3.4. Lithostratigraphic Unit IV**

Intervals: 395C-U1562A-55F-4, 14 cm, to 64X-CC, 33 cm; 395C-U1562B-2R-1, 3 cm, to 4R-1, 147 cm

Depths: Hole U1562A = 351.36–427.73 m CSF-A; Hole U1562B = 408.13–428.57 m CSF-A

Thickness: Hole U1562A = 76.37 m; Hole U1562B = 20.44 m

Age: late Miocene

Lithology: nannofossil ooze, nannofossil chalk

Unit IV is predominantly characterized by light gray nannofossil ooze, transitioning to nannofossil chalk toward the base of the unit. This unit begins in Section 395C-U1562A-55F-4, 14 cm, at a sharp contact between the overlying deformed silty clays and the underlying nannofossil ooze (Figure F10A). Subordinate beds (<3 m thick) of carbonate silty clay are also present near the upper and lower sections of this unit. The base of this unit is in Section 395C-U1562B-4R-1, at approximately 147 cm (428.57 m CSF-A), because Core 4R includes the interface between chalk and basalt basement between Sections 4R-1 and 4R-2. Bulk $CaCO_3$ ranges 59–78 wt% (average = 64 wt%); however, one exception is an interval of carbonate clayey silt (Sections 395C-U1562A-64X-3 through 64X-5), which has approximately 37 wt% $CaCO_3$. Unit IV is moderately to abundantly bioturbated, with greenish mottling associated with burrows (Figure F10B). Green banding is present in many intervals. Bands do not exhibit a different composition in smear slides from the surrounding sediments and appear to crosscut most burrows, implying they are the result of changes in sediment oxidation postdeposition (Figure F10C). Drilling disturbance in this unit presents as slight to severe fragmentation, with the severity and abundance of disturbance increas-

<figure><img src="image_13.png" /></figure>

**Figure F9.** Evidence for possible soft-sediment deformation in Unit III, Site U1562. A–C. Brecciated mud clast-like features closely resembling the Camouflage Central-Europe pattern. D–F. Other disorganization features such as folding, squeezing (base of D), and sharp, high-angle contacts between contrasting colored sediment packages.
ing downcore. Core recovery is also reduced for Unit IV in comparison to the upper units, which likely relates to degree of lithification (Figure F4).

Three clasts are present in Section 395C-U1562A-58X-1A, 28 cm (Figure F10D): a 6 cm sub-rounded basalt clast, a rounded 3 cm micrite clast, and a 2 cm subangular microgranular dark reddish clast. All three clasts are likely the result of fall-in from shallower depths in the hole, based on their position near the top of the core and the observed drilling disturbance at this depth, and hence are unlikely to be in place. A glassy layer with a diffuse upper boundary was identified near the base of the sedimentary column in Unit IV in interval 61X-2, 62–64 cm (Figure F10E).

In the underlying basalt basement units, a 65 cm thick layer of highly fragmented nannofossil chalk was recovered (interval 395C-U1562B-14R, 0–65 cm). This layer is pale brown, abundantly bioturbated and contains occasional greenish yellow and black glass throughout.

## 3.5. XRD results

A subset of squeeze cake residue samples (n = 10) were analyzed using X-ray diffraction (XRD). Results are consistent with smear slide and macroscopic observations (Figure F11; Table T4). The amount of calcite implied by the diffraction patterns is variable but consistent with CaCO₃ weight percent measurements. Minerals identified at this site are consistent with the terrigenous and authigenic minerals observed in smear slide and include quartz, assorted feldspar and pyroxene, pyrite, and calcite. XRD samples were not specifically prepared for clay mineral analysis, and peaks with a 2θ of <15° should be treated with caution; however, most samples display peaks in this region, consistent with the presence of clay minerals. Future analysis of the clay mineralogy in these samples could be useful for determining shifts in deposition processes and sediment sources.

<figure><img src="image_14.png" /></figure>

**Figure F10.** Sedimentary features from Unit IV, Hole U1562A. A. Unit III/IV contact. B. Green mottling observed in Unit IV, often associated with burrows. C. Green banding appearing to crosscut burrows (e.g., between 11 and 16 cm). D. Basalt, micrite, and granular red clasts found grouped near the top of 58X. E. Glass layer at ~63 cm >2 cm thick.

<figure><img src="image_15.png" /></figure>

**Figure F11.** Powder XRD results, Hole U1562A. Sample composition is variable. Patterns are indicative of the range of terrigenous and carbonate mineral assemblages. Mineral assemblage from the base of the sediment sequence is mainly calcite. Cal = calcite, Pyr = pyroxene, Feld = feldspar, Qz = quartz.
<table><caption>**Table T4.** XRD results, Site U1562. **Download table in CSV format.**</caption><thead><tr><th>Core, section, interval (cm)</th><th>Sample ID</th><th>Major minerals</th></tr></thead><tbody><tr><td>395C-U1562A-1H-1, 95-100</td><td>CAKE10970411</td><td>Quartz, calcite, feldspar, mica, pyroxene</td></tr><tr><td>6H-2, 145-150</td><td>CAKE10972721</td><td>Quartz, calcite, feldspar, pyroxene</td></tr><tr><td>13H-2, 145-150</td><td>CAKE10975891</td><td>Calcite, quartz, pyroxene, feldspar</td></tr><tr><td>17H-2, 145-150</td><td>CAKE10977711</td><td>Calcite, feldspar</td></tr><tr><td>21H-2, 145-150</td><td>CAKE10979541</td><td>Calcite, pyroxene, feldspar</td></tr><tr><td>28H-2, 145-150</td><td>CAKE10981741</td><td>Calcite, feldspar</td></tr><tr><td>36F-2, 145-150</td><td>CAKE10983671</td><td>Calcite, quartz, feldspar, pyrite</td></tr><tr><td>44F-2, 146-151</td><td>CAKE10985661</td><td>Calcite, feldspar</td></tr><tr><td>52F-2, 145-150</td><td>CAKE10987691</td><td>Calcite, feldspar</td></tr><tr><td>64X-6, 50-60</td><td>CAKE10992051</td><td>Calcite</td></tr></tbody></table>

<figure><img src="image_16.png" /><figcaption>**Figure F12.** Site U1562 location on Seismic Line JC50-1.</figcaption></figure>

# 4. Igneous petrology

Site U1562 is located on the western edge of VSR 3, where the estimated basement age is 13.9 Ma. This site is located near a series of normal faults that dip toward the northwest (Figure F12). Basalt coring in Hole 395C-U1562B reached ~560 m CSF-A (~130 m into basement) with 48% recovery (Figure F13). The sediment/basement contact was not recovered, but a quasi-interface with a small amount of glassy basaltic pillow fragments and breccia (<1 m) was sampled at the base of Hole 395C-U1562A.

## 4.1. Lithostratigraphy

Igneous rock cores from Site U1562 are mostly pillow basalts (>54%), with several thick sheet flow intervals recovered at 446–458 and 517–527 m CSF-A. Overall, the recovered basalts are sparsely to moderately olivine phyric, with some intervals also containing small plagioclase phenocrysts. Cores from this site also contain abundant peridotite and intercalated sediment (Figure F13).

Hole U1562A reached the sediment/basement interface at ~427.7 m CSF-A, where white calcareous ooze lies on top of glassy basalt fragments in Section 64X-CC. The underlying core recovered a weathered vesicular sheet flow of sparsely olivine phyric basalt.
Hole U1562B encountered the sediment-basement transition at 428.6 m CSF-A and reached a maximum depth of 559.5 m CSF-A within basement. Recovered material is primarily composed of sparsely to moderately olivine phyric basalt with significant amounts of intercalated carbonate and peperite fragments. Material from this hole is mostly pillow basalt, which makes up more than half the total recovery. It is typically hypocrystalline with chilled margins and mottled devitrification. Thin glass rinds are common, with some larger glass rinds and shards up to 3 cm thick. The rinds are mostly sparsely vesicular, with a few intervals ranging up to ~10% vesicularity. Vesicles commonly occur in bands near the edges of flows or pillow lobes. Peperite and intercalated carbonates are also common, with multiple regions of sediment-rich recovery. Peperites and lava breccias make up ~12% of the total volume of volcanic recovery. The peperites exhibit a variety of features indicative of sediment-lava interaction (e.g., Skilling et al., 2002), including abundant basalt clasts with quenched glassy rims, fluidal margins, sediment intrusion into cracks and vesicles, and baked carbonate matrixes. There are several sheet flows (as thick as 10 m) that are generally nonvesicular aside from large sparse vesicles concentrated at flow boundaries. These flows are

<figure><img src="image_17.png" /><figcaption>**Figure F13.** Lithostratigraphic summary, Hole U1562B. See Physical properties for detailed reflectance data.</figcaption></figure>
sparsely to moderately olivine phyric with medium-grained interiors that grade to fine-grained chilled margins at flow boundaries. As at other Expedition 395 sites, these sheet flows also exhibit higher magnetic susceptibility (MS) and higher L\* color reflectance than pillow lava intervals (Figure F13; see Physical properties). Most basalts show slight to moderate alteration with carbonate veins throughout (see Alteration petrology and structural geology). Sections 395C-U1562B-8R-2 and 10R-1 have strongly altered vesicular flow tops.

**4.2. Core descriptions**

Descriptions are based on a combination of detailed macroscopic observations of core sections, microscopic thin section observations, and physical properties measurements (e.g., MS, color reflectance, and wireline logs). Significant characteristics are summarized in the visual core descriptions (VCDs).

Igneous lithologies at Site U1562 are divided into three principal morphologic categories: pillow lavas, sheet flows, and peperites (Figures F14, F15). Pillow lavas consist of aphyric to sparsely olivine-phyric basalt fragments characterized by chilled curved margins, concentric vesicle bands, and thin glass rinds. Sheet flows recovered at this site are 2–10 m thick with coarser groundmass interiors. Approximately ~25% of the recovered lava is not assigned a flow morphology because of ambiguity distinguishing thin sheet flows from large pillows and lobate flows. Vesicles are sparsely to moderately abundant, often filled, and commonly occur in aligned bands. Veins and fractures frequently contain clay, celadonite, and Fe-oxide, with variable extents of background alteration (see Alteration petrology and structural geology).

Peperitic layers are characterized by glass shards and lava fragments in a carbonate matrix and show evidence for lava-sediment interaction (e.g., baked sediment, basalt fragments with quenched rims, and fluidal margins). These units often contain abundant fresh glass shards and fragments. Thick glass rinds (>1 cm) are relatively abundant in this core. In addition to peperitic intervals, some horizons contain lava breccias that lack clear evidence for lava-sediment interaction. Occasionally, there are thin layers of intercalated calcareous mudstone, which is sometimes

<figure><img src="image_18.png" /><figcaption>**Figure F14.** Common lithologies, Hole U1562B. A. Sheet flows with intercalated sediment. B. Pillow lavas with intercalated sediment and peperite fragments.</figcaption></figure>
brecciated. A 65 cm thick layer of mudstone was recovered in Section 395C-U1562B-14R-2 at ~475 m CSF-A.

We used the presence of sediment-rich horizons (i.e., significant intercalated sediment or peperite) and mineralogical changes (e.g., olivine-phyric to plagioclase-phyric basalt) to divide the basement succession into igneous lithologic units (Table T5). Because of incomplete recovery and a general lack of well-defined contacts, our unit boundary locations are approximate and preliminary. We note that the cores with the lowest recovery are associated with pillow fragments, peperites, and/or intercalated sediment. This pattern is consistent with preliminary observations from the downhole logging data (see Downhole measurements), which show broad correlations between recovery rate, rock density, and lava morphology.

### 4.2.1. Hole U1562A

Less than 1 m of basement was recovered at the base of Hole U1562A, consisting of glassy basalt fragments overlying a weathered and vesicular sheet flow.

<figure><img src="image_19.png" /></figure>

**Figure F15.** Typical lithologies, Hole U1562B. A. Vesicular sheet flow top (4R-2A, 0–31 cm). B. Small pillow lava fragment with 1 cm thick glass rind (19R-1A, 36–43 cm). C. Fracture between two pillow fragments filled with altered peperitic material (32R-1A, 43–52 cm). D. Pillow fragment with network of peperitic and carbonate veins, mostly empty vesicles, and thick glass rind (24R-2A, 35–39 cm). E. Peperite with glass rinds around basalt clasts (24R-1A, 79–83 cm). F. Baked carbonate mudstone with a network of thin veins (17R-2A, 75–81 cm).

<table><caption>**Table T5.** Igneous lithologic units, Hole 395C-U1562B. Download table in CSV format.</caption><thead><tr><th>Unit</th><th>Interval</th><th>Depth CSF-A (m)</th><th>Description</th></tr></thead><tbody><tr><td></td><td>395C-U1562B-</td><td></td><td></td></tr><tr><td>L1</td><td>4R-2, 0 cm, to 5R-2, 148 cm</td><td>428.57–434.72</td><td>Vesicular sheet flows with minor amounts of olivine accumulation in the base</td></tr><tr><td>L2</td><td>5R-3, 0 cm, to 14R-1, 134 cm</td><td>434.72–475.54</td><td>Aphyric to sparsely olivine phyric pillow basalts with minor amounts of intercalated baked mudstone</td></tr><tr><td>L3</td><td>14R-3, 0 cm, to 16R-2, 34 cm</td><td>476.2–485.68</td><td>Sparately plagioclase phyric pillow basalts with occasional peperite fragments overlain by baked carbonate mudstone</td></tr><tr><td>L4</td><td>17R-1, 0 cm, to 26R-1, 7 cm</td><td>485.9–527.77</td><td>Aphyric to sparsely olivine phyric basalt; fine-grained pillow lavas grade into medium-grained sheet flows downsection</td></tr><tr><td>L5</td><td>26R-1, 7 cm, to 32R-2, 140 cm</td><td>527.77–559.6</td><td>Glassy lava breccias and pillow fragments with aggregates of olivine microphenocrysts</td></tr></tbody></table>
### 4.2.2. Hole U1562B

This hole can be divided into five igneous lithologic units (Figure F13; Table T5). The top is marked by a ~6 m thick altered vesicular sheet flow with minor amounts of olivine accumulation at its base (Unit 1). This sheet flow is underlain by a series of aphyric to sparsely olivine phyric pillow lavas with a thin sheet flow at the base and minor amounts of intercalated baked mudstone (Unit 2). Unit 2 overlies over half a meter of variably baked mudstone with manganese spots at ~475 m CSF-A. This sediment horizon forms the boundary between Units 2 and 3. Unit 3 consists of ~12 m of pillow basalts with sparse plagioclase and olivine phenocrysts intermixed with occasional peperite fragments. This basalt interval is underlain by another sediment-rich peperite horizon, beneath which Unit 4 includes almost 40 m of aphyric to sparsely olivine phyric basalt dominated by fine-grained pillows, which grade into a medium-grained sheet flow near the base of the unit. Another notable peperite interval (>1 m thick) forms the boundary between Units 4 and 5. Unit 5 consists of glassy lava breccias and pillow fragments that contain olivine microphenocryst conglomerates. This lowermost unit had low recovery to the base of the hole.

## 4.3. Thin sections

Thin sections were sampled from Hole U1562B with an average spacing of ~7 m (see **Core descriptions**), resulting in 18 thin sections, mostly from pillow lavas. They are, on average, sparsely to moderately olivine phytic (<10%) with relatively little alteration (Figure F16). Olivine phenocrysts range from small microphenocrysts to large, euhedral olivines up to ~4 mm across. Skeletal and swallowtail olivines are common in the groundmass, indicating rapid cooling. Plagioclase is the most abundant groundmass mineral, usually forming acicular or skeletal crystals without significant zoning. Thin sections from Igneous Lithologic Unit 3 contain twinned plagioclase phenocrysts up to ~2 mm long. The groundmass usually exhibits intergranular and intersertal textures containing clinopyroxene-bearing mesostasis, opaque oxides, and altered glass. Thin sections sampled from sheet flows are variable but tend to have a more crystallized groundmass with plagioclase, clinopyroxene and opaque oxides. Vesicles occur in low abundances (usually <5%) and are often filled with secondary phases such as calcite and celadonite (see **Alteration petrology and structural geology**).

## 4.4. Geochemistry

Shipboard measurements on basalts from Hole U1562B include portable X-ray fluorescence (pXRF) and inductively coupled plasma–atomic emission spectroscopy (ICP-AES) analyses (see **Geochemistry and microbiology** in the Expedition 395 methods chapter [Parnell-Turner et al., 2025a]).

The pXRF analyses were primarily used for preliminary characterization of the hole during shipboard operations. Raw counts from pXRF analyses are shown in Figure F17. Despite significant scatter, major elements such as Mg, Al, and Si roughly group into several clusters with offsets that sometimes align with our lithostratigraphic unit boundaries. Although we caution against overin-

<figure><img src="image_20.png" /><figcaption>**Figure F16.** Basalt thin sections in (A–C) XPL and (D) PPL, Hole U1562B. A. Pillow lava showing skeletal olivine (Ol) phenocrysts in a cryptocrystalline groundmass (20R-2W, 96–99 cm). B. Glassy domain in a sheet flow (5R-1W, 23–26 cm). Pl = plagioclase. C. Elongate, twinned plagioclase laths in pillow lava (15R-3W, 25–28 cm). D. Pillow lava with dendritic olivines showing flow alignment (12R-1W, 96–99 cm). V = vesicle.</figcaption></figure>
interpreting raw pXRF data, we note that the Unit 3 to 4 transition (~485 m CSF-A) is marked by slight increases in Mg, Al, and Si, as well as increases in incompatible trace elements such as Ti, Y, and Zr. On average, Unit 3 has slightly lower incompatible element concentrations than the other units, with another possible decrease in incompatible elements across the Unit 4–5 transition (~528 m CSF-A).

Similar geochemical offsets are also weakly reflected in ICP-AES analyses, which were performed on 18 samples that are co-located with the thin sections. Measurements of select major and trace elements are shown in Figure F18. MgO varies from 8.47 to 9.88 wt% with an average value of

<figure><img src="image_21.png" /><figcaption>**Figure F17.** pXRF compositional data (raw counts) for selected major and trace elements, Hole U1562B.</figcaption></figure>

<figure><img src="image_22.png" /><figcaption>**Figure F18.** Bulk rock ICP-AES analyses for selected major and trace elements, Hole U1562B.</figcaption></figure>
~9.49 wt%. Average Zr/Y is ~1.9, consistent with values from VSR basalts dredged from the ridge axis (Murton et al., 2002; Jones et al., 2014).

**4.5. Correlations and interpretation**

Core description results are combined with thin section observations, physical properties, down-hole logging results, and shipboard geochemical analyses to develop a preliminary interpretation of Site U1562. As found at other sites, there is a weak correlation between MS and lithology (see **Physical properties**), with sheet flows exhibiting higher MS on average than pillow lavas and peperites (Figure F13). This correlation is probably caused by greater abundance of Fe-oxides (e.g., magnetite and titanomagnetite) within sheet flows. Similarly, sheet flows exhibit slightly higher L* color reflectance (Figure F13) and alteration extents (see **Alteration petrology and structural geology**) on average.

Hole U1562B had a markedly higher recovery rate than the other VSR hole, Hole U1563B (48% and 29%, respectively). However, we note that Hole U1563B also had a significantly higher proportion of sediment and peperite in the cores, which tend to be associated with lower recovery. Coring may preferentially sample peperitic zones where the carbonate matrix is baked and rich in basalt clasts and much of the surrounding sediment material is lost. Similarly, recovery of the one known sediment horizon of any significant thickness is incomplete: a mudstone layer ~65 cm thick was recovered from ~475 m CSF-A, but the downhole image log suggests that this sediment layer is probably ~3 m thick (see **Downhole measurements**). This sediment layer defines the boundary between Igneous Lithologic Units 2 and 3 and likely represents a significant hiatus between eruptions for such thick sediment accumulation. Assuming the average sedimentation rate estimated for the base of Hole U1562A, it would take on the order of ~10⁵ y to accumulate several meters of sediment, suggesting that the upper basalt sequence is significantly younger than the lower basalt sequence. This observation is also consistent with biostratigraphic analyses of foraminifers, nanofossils, and bolboforms, which indicate this sediment layer is older than the sediment near the sediment/basement contact (see **Micropaleontology**).

Multiple horizons of peperite were recovered, indicating that lava has repeatedly flowed or erupted into carbonate ooze at this site. The prevalence of sediment at Sites U1562 and U1563 is significant, given that both are VSRs and thus thought to have higher average magma supply than the VST sites. One might therefore expect more frequent eruptions with less time for sediment accumulation than at Sites U1554 and U1555. Instead, there must be a significant amount of sediment accumulation at this site to produce peperite and mudstone intervals multiple meters thick. We speculate that the VSR sites may be sampling late stage off-axis eruptions or eruptions that flowed off-axis into already sedimented areas.

**5. Alteration petrology and structural geology**

At Site U1562, ~0.78 and ~65.39 m of basement core was recovered from Holes 395C-U1562A and 395C-U1562B, respectively. Here, we provide a visual description of the style and composition of basalt alteration and secondary mineral fill of their vesicles and document the occurrence and mineral fill of fractures from the basement cores.

**5.1. Basalt alteration**

Basalt from Site U1562 contains numerous intervals of intermixed peperite and completely altered carbonate sediments, which comprise ~2.4% of the recovered basement core at this site. Peperites at Site U1562 have a matrix of altered carbonate sediments that contain fragments of basalt and basaltic glass (see **Igneous petrology**). The alteration reported here is for basalt core and the basalt fragments in the peperite intervals.

We estimate that ~72% of the basalt core obtained from Holes U1562A and U1562B is slightly altered, 18% moderately altered, 8% highly altered, ~2% completely altered, and <1% unaltered basalt (Figure F19). The predominant alteration style of the basalt at Site U1562 is pervasive (background) (Figure F20). Alteration halos around fractures appear frequently at ~461–533 m
CSF-A in Hole U1562B, and localized patches of alteration are commonly observed at 434–461 and 533–553 m CSF-A. Alteration intensity at Site U1562 does not show any obvious correlation to basement core lithology (see **Igneous petrology**).

The most commonly occurring basalt alteration mineral assemblage at Site U1562 consists of Fe-
oxide/oxyhydroxides + phyllosilicate and celadonite (Figure **F20**). Celadonite occurs as a minor
component of the alteration assemblage at various depths in Hole U1562B. Rims of basalt clasts in
peperite intervals display strong to complete alteration to palagonitic material (rich in Fe-
oxide/oxyhydroxides), which in some clasts decreases in intensity toward their centers. In thin
section, olivine phenocrysts are variably altered to a pale brown to green saponite phase or idding-
sitized (Figure **F21A, F21B**). The basaltic groundmass appears variably altered mainly to smectite,
likely saponite and Fe-saponite, celadonite, and Fe-celadonite (Figure **F21C, F21D**). Disseminated

<figure><img src="image_23.png" /><figcaption>**Figure F19.** Proportional intensity of basalt alteration for all cores, Site U1562.</figcaption></figure>

<figure><img src="image_24.png" /><figcaption>**Figure F20.** Lithologic interpretation and units, Hole U1562B, and alteration intensity variation, Holes U1562A and U1562B. (See Igneous petrology.)</figcaption></figure>
magnetite is observed, some of which has a dendritic morphology, along with common oxide phases.

An altered olivine from thin section Sample 395C-U1562B-17R-2, 109–112 cm, was analyzed with energy dispersive spectrometry (EDS). Elemental maps of the altered olivine were acquired (Si, O, Al, Ca, Mg, Fe, K, and Na), and two zones of interest on the altered olivine were analyzed for their EDS spectra to better characterize the alteration (Figure F22). Zone 1 shows strong spectral peaks

<figure><img src="image_25.png" /></figure>

**Figure F21.** Alteration, Hole U1562B. A, B. Saponite/chlorite alteration (1) of olivine (2) (5R-1, 23–26 cm). C, D. Saponite alteration (3) and celadonite alteration (4) (17R-2, 109–112 cm). Left: PPL, right: XPL.

<figure><img src="image_26.png" /></figure>

**Figure F22.** Altered olivine (395C-U1562B-17R-2, 109–112 cm). A. EDS element map showing secondary electron map overlaid with Mg, Al, Fe, and K chemistry maps. B, C. EDS spectra of (B) Zone 1 and (C) Zone 2. cps = counts per second.
for Mg, Si, and O with minor Fe. Zone 2 shows strong spectral peaks for Si, Mg, and O with minor Al and Fe and very minor Ca. Zone 1 represents unaltered olivine, close to the forsterite end-member, and Zone 2 is interpreted to be parts of the olivine phenocryst undergoing saponitization by replacement of Mg with Si, Al, and Ca.

The fraction of vesicles filled with alteration minerals varies between 10% and 100% at Site U1562. Vesicle-filling minerals are mostly Fe-oxide/oxyhydroxides, celadonite, and calcite, with moderate saponite and minor zeolite (phillipsite) (Figure F23). Thin section Sample 395C-U1562B-30R-1, 4–7 cm, displays calcite-filled vesicles with saponite spherules on their rims, with an outer cel-adonite rim (Figure F23G, F23H), as well as other vesicles containing calcite and a zeolite phase tentatively identified as phillipsite (Figure F23C). The mineral fill of most vesicles shows a color zonation, with Fe-oxide/oxyhydroxides or saponite rims to celadonite-filled vesicles presenting a range of colors from pale blue to pale green. Dark blue celadonite is uncommon in vesicles from Hole U1562B. There is no correlation between the percentage of vesicles filled and the alteration intensity of the basalt core at Site U1562. Some vesicles show <1 mm wide alteration halos in the basalt around them.

Vesicles with multiple infilling minerals from thin section Sample 395C-U1562B-30R-1, 4–7 cm (shown in Figure F23G, F23H), were analyzed using EDS (Figure F24). Elemental maps (Si, O, Al, Ca, Mg, Fe, K, and Na) and EDS spectra from two zones of interest were examined to better char-acterize the vesicle alteration mineralogy (Figure F24C, F24D). In Zone 1, a spherule-like material in the vesicles shows strong spectral peaks for Ca and O and minor peaks for Si, Al, Mg, and Fe. Zone 2 shows strong spectral peaks for Ca and O with minor Mg. Zone 2 can be inferred to repre-sent Mg-calcite, and Zone 1 may represent a chlorite/smectite composition for the spherules on the edge of the vesicle, although the EDS spectra also contain signals of the Mg-calcite infill that may extend underneath the clay on the thin section. The K map highlights the presence of cel-adonite around the vesicle rims (between the chlorite/smectite spherules and Mg-calcite fill).

**5.2. Structural geology**

Fracture analysis at Site U1562 revealed 6 fractures in Hole U1562A (Section 64X-CC and Core 65X) and 1399 fractures in basement core from Hole U1562B. For Hole U1562B, an occurrence rate of ~21 fractures per meter of recovered core is reported (~17–18 fractures per meter of

<figure><img src="image_27.png" /></figure>

**Figure F23.** Vesicles, Hole U1562B. A, B. Vesicle filled with phillipsite (1) and a smectite rim (2) in (A) PPL and (B) XPL (15R-3, 25–28 cm). C, D. Layered vesicle (3) showing celadonite zonation in (C) PPL and (D) XPL (32R-1, 94–97 cm). E, F. Vesicle filled with calcite (4) in (E) PPL and (F) XPL (30R-1, 4–7 cm). G, H. Layered vesicles displaying smectite spherules (5), celadonite rims (6), and calcite infilling (7) in (G) PPL and (H) XPL (30R-1, 4–7 cm).
curated core). Fracture density seems invariant with depth, with only few local exceptions of low-
fracture density at ~432, ~454, ~475, ~485, and 548 m CSF-A (Figure F25). Most fractures
recorded at Site U1562 have widths ≤0.5 mm (64%) (Figure F26). The widest fractures recorded
include two 8–10 mm wide carbonate-filled fractures in Hole U1562B (Figure F27). Most frac-

<figure><img src="image_28.png" /></figure>

**Figure F24.** Calcite-filled vesicles with chlorite/smectite spherules and celadonite rims (395C-U1562B-30R-1, 4–7 cm). A. EDS element map displaying overlaid Mg, Al, Ca, and Fe chemistry. B. EDS K map displaying K-rich celadonite at vesicle rims. C. EDS spectrum of Zone 1. D. EDS spectrum of Zone 2. cps = counts per second.

<figure><img src="image_29.png" /></figure>

**Figure F25.** Fracture density normalized by curated section length, Hole U1562B.
tures are classified as partially open (42.2%) or veins (37.6%) with anastomosing (41.4%) or planar (45.5%) shapes, and most fractures are observed to exist in a crosscutting network (52%) (Figure F28). Fracture attitude was not recorded for this site because of time constraints during core description.

Fracture mineral fill classification was determined by color, visual inspection under a hand lens, and reaction to dilute HCl acid. In Hole U1562A, the mineral fill of the six fractures measured is primarily cryptocrystalline to microcrystalline carbonate ± Fe-oxide/oxyhydroxide ± celadonite. In Hole U1562B, the mineral fill of the 1399 documented fractures is mainly cryptocrystalline to microcrystalline carbonate ± Fe-oxide/oxyhydroxide with minor occurrences of phyllosilicate and celadonite (Figures F29, F30A). In thin section, some Fe-oxide/oxyhydroxide and celadonite fracture fills are observed (Figure F30B). Peperite and altered carbonate sediment intervals show a later stage of brittle deformation resulting in the formation of carbonate veins (Figure F30C). These carbonate veins commonly cut through the carbonate matrix around the basaltic fragments but occasionally also cut through the basaltic fragments. Fracture alteration halos range 1–20 mm wide with colors from brown, pale gray, green-gray, to green-brown. The mineral fill of vesicles in these alteration halos is mostly carbonate and phyllosilicate rich with some celadonite and Fe-oxide/oxyhydroxides.

<figure><img src="image_30.png" /><figcaption>**Figure F26.** Fracture width distribution, Site U1562.</figcaption></figure>

<figure><img src="image_31.png" /><figcaption>**Figure F27.** Carbonate filled fractures, Hole U1562B. A. 30R-1, 71–76 cm. B. 31R-1, 87–92 cm.</figcaption></figure>
<figure><img src="image_32.png" /></figure>

<figure><img src="image_33.png" /></figure>

<figure><img src="image_34.png" /></figure>

**Figure F28.** Basalt core fractures, Site U1562. A. Percentages of observed fracture types. B. Percentages of observed fracture shapes. C. Percentages of observed fracture connectivity.

<figure><img src="image_35.png" /></figure>

**Figure F29.** Mineral fill percentages for individual fractures, Hole U1562B.
<figure><img src="image_36.png" /></figure>

**Figure F30.** A. Altered highly vesicular basalt showing a chlorite/celadonite/calcite vein (1) displaying an oxide-rich halo (2) with abundant vesicles (3) (395C-U1562A-65X-1, 24–29 cm). B. Green celadonite vein (4) cutting through basalt and a saponite-filled vesicle (5) (395C-U1562B-5R-3, 68–71 cm). C. Carbonate-filled fractures cutting through altered carbonate sediments (6) and palagonitized basalt glass (7) (15R-2, 10–20 cm).

**6. Micropaleontology**

At Site U1562, a 429.8 m long interval of upper Miocene to upper Pleistocene silty clay and nanno-fossil chalk was recovered across multiple holes. Micropaleontological analyses were undertaken on samples from Hole 395C-U1562A, which recovered sediments in cores from 0 to 429.8 m CSF-A, and Hole 395-U1562C, which recovered core from 0 to 300.73 m CSF-A. The APC and XCB systems were used in both holes. In Hole U1562A, basement was encountered at ~430 m CSF-A in Section 64X-CC. Below this depth, Core 65X contains 0.68 m of basalt, confirming the transition from sediment to basement. Samples from the uppermost 300.73 m were analyzed for micropaleontology from Holes U1562A and U1562C, and below this depth only samples from Hole U1562A were available for study. Biohorizons used in the age model are based on calcareous nannoplankton, planktonic foraminifers, and bolboforms. Calcareous nannofossils and planktonic foraminifers are present with varying abundances, from barren or nearly barren samples to those with very high abundances. This change in abundance most likely reflects glacial-interglacial variability in temperatures, salinity, and/or ice cover in the Quaternary part of the succession. Bolboforms, when present, are generally rare or few.

**6.1. Calcareous nannofossils**

A total of 47 core catcher samples from Hole U1562A and 96 core catcher and working-half section samples from Hole U1562C were studied for calcareous nannofossils. One additional sample from Hole 395C-U1562B was taken from the mudstone found ~45 m below the top of the igneous succession. Observations were undertaken using plane-polarized light, cross-polarized light, and circular-polarized light. A list of calcareous nannofossil bioevents is provided in Table T6; these bioevents are mostly based on Hole U1562C where it overlaps in depth with Hole U1562A because the former was studied in more detail shipboard during Expedition 395. One biohorizon is included from Hole U1562A, top *Coccolithus miopelagicus*, because Hole U1562C was not drilled to this depth. Calcareous nannofossils are present in most samples although with distinctly differing abundances alternating in intervals downcore, from few (1–5 per field of view [FOV]) to dominant (hundreds per FOV). In a distinct interval between Samples 395-U1562C-7H-CC (54.2 m CSF-A) and 15H-CC (129.79 m CSF-A), more than half of the samples have very few to rare nannofossils or are barren of nannofossils. Preservation is mostly good in the uppermost ~130 m with occasional intervals of moderate preservation. An interval of very good preservation occurs between ~130 and ~250 m CSF-A, below which preservation is mostly good.

Samples from the Pleistocene succession recovered in Hole U1562C show distinct changes in the abundance of nannofossils and their species composition downcore. The base common *Emiliania huxleyi* biohorizon (0.09 Ma) is present in the first core between Samples 1H-1, 40 cm (0.4 m CSF-A), and 1H-2, 82 cm (2.31 m CSF-A). The biohorizon base *E. huxleyi* (0.29 Ma) is then placed
between Samples 1H-3, 140 cm (4.39 m CSF-A), and 1H-CC (5.32 m CSF-A), followed by top acme *Gephyrocapsa caribbeanica* (0.28 Ma) between Samples 1H-CC (5.32 m CSF-A) and 2H-2, 100 cm (7.82 m CSF-A), and top *Pseudoemiliania lacunosa* (0.43 Ma) between Samples 2H-2, 100 cm (7.82 m CSF-A), and 2H-3, 142 cm (9.74 m CSF-A). Two biohorizons, base acme *G. caribbeana* (0.56) and top *Reticulofenestra asanoi* (0.91 Ma) are both placed between Samples 3H-1, 59 cm (15.39 m CSF-A), and 3H-3, 130 cm (19.12 m CSF-A), and will need further sampling in the cores to be resolved. An interval with very few nannofossils that also contains two biohorizons, top *Helicosphaera sellii* (1.24 Ma) and top *Calcidiscus macintyrei* (1.60 Ma), occurs between Samples 3H-3, 130 cm (19.12 m CSF-A), and 4H-4, 86 cm (29.69 m CSF-A). No other Pleistocene or late Pliocene biohorizons were identified because of the very rare and sporadic occurrence of *Discoaster* species. The next, middle Pliocene biohorizon is top *Reticulofenestra pseudoumbilicus* (3.82 Ma) between Samples 17F-CC (144.17 m CSF-A) and 18F-CC (148.45 m CSF-A). Two calcareous nannofossil biohorizons, the top paracme of *R. pseudoumbilicus* (7.1 Ma) between Samples 39F-CC (237.52 m CSF-A) and 40F-CC (242.22 m CSF-A) and top *C. miopelagicus* (11.04 Ma) between Samples 395C-U1562A-59X-CC (378.93 m CSF-A) and 60X-CC (383.06 m CSF-A), were identified in the upper Miocene. The presence of *C. miopelagicus* constrains the bottom of the hole to be older than 11.04 Ma (see also Age model). Sample 395C-U1562B-14R-2, 12–17 cm, taken from the 65 cm thick mudstone below the top of the igneous succession, is dominated by a moderately preserved calcareous nannofossil assemblage consisting of *R. pseudoumbilicus*, medium sized *Reticulofenestra* species and *Reticulofenestra perplexa*, *Sphenolithus* sp., and *Calcidiscus* sp. The assemblage looks significantly different from the one found at the base of Hole U1562A (Sample 46X-CC; 427.4 m CSF-A). *C. miopelagicus* is present and gives an age estimate that is older than 11.04 Ma (top *C. miopelagicus* in Raffi et al., 2020).

## 6.2. Planktonic foraminifers

Samples at Site U1562 were studied in Holes U1562A–U1562C. Samples from Holes U1562A and U1562B were processed and studied in the micropaleontology laboratory at University College London, and those from Hole U1562C were processed and studied on board *JOIDES Resolution*. A total of 31 core catcher samples were studied from Hole U1562A in the depth interval 0–476 m CSF-A, spanning almost the entire sedimentary succession, including one sample from the mud-line. A single sample was studied from Hole U1562B from a 65 cm thick layer of sediment located ~45 m below the top of the igneous basement succession at ~476 m CSF-A. A total of 47 core catcher samples were studied for planktonic foraminifers from Hole U1562C, spanning 0–301 m CSF-A. A list of planktonic foraminifer bioevents is provided in Table T7. Preservation is excellent or very good in most samples except for some samples from the deeper part of the succession, which are indurated and the tests are infilled but in which preservation is still rated as good. Plank-

<table><caption>**Table T6.** Calcareous nannofossil bioevents, Site U1562. B = base, Bc = base common, Ba = base acme, T = top, Ta = top acme, Tpa = top paracme. **Download table in CSV format.**</caption><thead><tr><th>Biohorizon</th><th>Marker species</th><th>Age (Ma)</th><th>(Sub)zone base</th><th>Top core, section, interval (cm)</th><th>Bottom core, section, interval (cm)</th><th>Top depth CSF-A (m)</th><th>Bottom depth CSF-A (m)</th><th>Midpoint depth CSF-A (m)</th><th>±</th></tr></thead><tbody><tr><td>1</td><td>Bc Emiliania huxleyi</td><td>0.09</td><td></td><td>395-U1562C-1H-1, 40</td><td>395-U1562C-1H-2, 82</td><td>0.40</td><td>2.31</td><td>1.36</td><td>0.96</td></tr><tr><td>2</td><td>Ta Gephyrocapsa caribbeanica</td><td>0.28</td><td></td><td>1H-CC</td><td>2H-2, 100</td><td>5.32</td><td>7.82</td><td>6.57</td><td>1.25</td></tr><tr><td>3</td><td>B Emiliania huxleyi</td><td>0.29</td><td>NN21</td><td>1H-3, 140</td><td>1H-CC</td><td>4.39</td><td>5.32</td><td>4.86</td><td>0.46</td></tr><tr><td>4</td><td>T Pseudoemiliania lacunosa</td><td>0.43</td><td>NN20</td><td>2H-2, 100</td><td>2H-3, 142</td><td>7.82</td><td>9.74</td><td>8.78</td><td>0.96</td></tr><tr><td>5</td><td>Ba Gephyrocapsa caribbeanica</td><td>0.56</td><td></td><td>3H-1, 59</td><td>3H-3, 130</td><td>15.39</td><td>19.12</td><td>17.26</td><td>1.86</td></tr><tr><td>6</td><td>T Reticulofenestra asanoi</td><td>0.91</td><td></td><td>3H-1, 59</td><td>3H-3, 130</td><td>15.39</td><td>19.12</td><td>17.26</td><td>1.86</td></tr><tr><td>9</td><td>T Helicosphaera sellii (Atlantic)</td><td>1.24</td><td></td><td>3H-3, 130</td><td>4H-4, 86</td><td>19.12</td><td>29.69</td><td>24.41</td><td>5.29</td></tr><tr><td>12</td><td>T Calcidiscus macintyrei</td><td>1.60</td><td></td><td>3H-3, 130</td><td>4H-4, 86</td><td>19.12</td><td>29.69</td><td>24.41</td><td>5.29</td></tr><tr><td></td><td>Base Pleistocene</td><td>2.59</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td></td><td>Base upper Pliocene</td><td>3.60</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>19</td><td>T Reticulofenestra pseudoumbilicus</td><td>3.82</td><td>NN16</td><td>17F-CC</td><td>18F-CC</td><td>144.17</td><td>148.45</td><td>146.31</td><td>2.14</td></tr><tr><td></td><td>Base Pliocene</td><td>5.33</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>22</td><td>Tpa Reticulofenestra pseudoumbilicus</td><td>7.10</td><td></td><td>39F-CC</td><td>40F-CC</td><td>237.52</td><td>242.22</td><td>239.87</td><td>2.35</td></tr><tr><td></td><td></td><td></td><td></td><td>395C-U1562A-59X-CC</td><td>395C-U1562A-60X-CC</td><td>378.93</td><td>383.06</td><td>380.995</td><td>2.06</td></tr><tr><td>28</td><td>T Coccolithus miopelagicus</td><td>11.04</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>
tonic foraminifers are common to dominant in all samples except for the interval between Samples 395-U1562C-10H-CC (82.70 m CSF-A) and 14H-CC (120.71 m CSF-A) and correlative levels in Hole U1562A, which are discussed further below.

Sample 395C-U1562A-1H-1, 0 cm, from the mudline, contains many iron-stained shells, which may indicate a component of reworked or disturbed material, as well as a similar proportion of fresh-looking specimens. The assemblage is diverse and indicative of interglacial conditions. Large *Globigerina bulloides* is abundant and shows apparent intergradation with *Globigerina cariacoensis* and *Globigerina umbilicata*. Both *Neogloboquadrina incompta* (dextral) and *Neogloboquadrina pachyderma* (sinistral) are present. The most interesting aspect of this sample is the presence of rare specimens of *Globorotalia tumida*, a species that was not found deeper in the sediment or in the mudline samples collected at other Expedition 395 sites. This species peaks in abundance at the equator and also occurs commonly in warm boundary currents, but it is generally absent or extremely scarce in higher latitudes (Siccha and Kucera, 2017). Its presence may be a function of warm Holocene conditions. It is unlikely to be an Anthropocene invader because most individuals are iron stained, probably indicating prolonged exposure on the seafloor.

Sample 395C-U1562A-1H-CC (1.99 m CSF-A) contains frequent to abundant encrusted sinistral *N. pachyderma* and is therefore attributed to the *N. pachyderma* Zone. Also present are *G. bulloides*, *Turborotalita quinqueloba*, *G. cariacoensis*, *G. umbilicata*, *Globoconella inflata*, *Globorotalia scitula*, and *Globigerinita glutinata*. The base common encrusted sinistral *N. pachyderma*, marking the base of the *N. pachyderma* Zone at 1.82 Ma, is most closely constrained in Hole U1562C between Samples 395-U1562C-3H-CC (24.62 m CSF-A) and 4H-CC (34.32 m CSF-A). Samples 395C-U1562A-4H-CC (31.06 m CSF-A) and 5H-CC (40.41 m CSF-A) contain *G. inflata* in the absence of encrusted *N. pachyderma* (although rare sinistral unencrusted specimens are present in the latter sample) and are therefore assigned to the *G. inflata* Zone. The base of *G. inflata*, marking the base of the *G. inflata* Zone at 2.06 Ma, is between Samples 5H-CC (40.41 m CSF-A) and 6H-CC (49.71 m CSF-A). Sample 6H-CC (49.71 m CSF-A) lacks *G. inflata* and *G. umbilicata* and is therefore assigned to the *G. bulloides* Zone. The bottom of *G. inflata* was found at a dis-

<table><caption>**Table T7.** Planktonic foraminifer bioevents, Site U1562. B = base, Bc = Base common, T = top, X = coiling reversal, d-s = dextral to sinistral, sin = sinistral. IRD = ice-rafted debris. PRZ = partial range zone, LOZ = lowest occurrence zone, CRZ = concurrent range zone. **Download table in CSV format.**</caption><thead><tr><th>Biohorizon</th><th>Marker species</th><th>Age (Ma)</th><th>(Sub)zone base</th><th>Top core, section, interval (cm)</th><th>Bottom core, section, interval (cm)</th><th>Top depth CSF-A (m)</th><th>Bottom depth CSF-A (m)</th><th>Midpoint depth CSF-A (m)</th><th>±</th></tr></thead><tbody><tr><td>F1</td><td>Bc Neogloboquadrina pachyderma (sin)</td><td>1.82</td><td>N. pachyderma PRZ</td><td>395C-U1562A-1H-CC</td><td>395C-U1562A-4H-CC</td><td>1.99</td><td>31.11</td><td>16.55</td><td>14.56</td></tr><tr><td>F2</td><td>B Globoconella inflata</td><td>2.06</td><td>G. inflata LOZ</td><td>5H-CC</td><td>6H-CC</td><td>40.41</td><td>49.71</td><td>45.06</td><td>4.65</td></tr><tr><td>F3</td><td>B Globigerina umbilicata</td><td>2.07</td><td></td><td>5H-CC</td><td>6H-CC</td><td>40.41</td><td>49.71</td><td>45.06</td><td>4.65</td></tr><tr><td>F4</td><td>T Neogloboquadrina atlantica</td><td>2.26</td><td>G. bulloides PRZ</td><td>9H-CC</td><td>10H-CC</td><td>78.44</td><td>88.05</td><td>83.25</td><td>4.81</td></tr><tr><td>F5</td><td>B Globigerina cariacoensis</td><td>2.26</td><td></td><td>9H-CC</td><td>10H-CC</td><td>78.44</td><td>88.05</td><td>83.25</td><td>4.81</td></tr><tr><td></td><td>Base common IRD</td><td></td><td></td><td>14H-CC</td><td>18H-CC</td><td>125.61</td><td>163.41</td><td>144.51</td><td>18.90</td></tr><tr><td></td><td>Base Pleistocene</td><td>2.59</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td></td><td>Base upper Pliocene</td><td>3.60</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>F6</td><td>B Globoconella puncticulata</td><td>4.54</td><td>G. puncticulata/N. atlantica CRZ</td><td>18H-CC</td><td>19H-CC</td><td>163.41</td><td>173.47</td><td>168.44</td><td>5.03</td></tr><tr><td>F7</td><td>B Globorotalia crassaformis</td><td>4.60</td><td></td><td>18H-CC</td><td>19H-CC</td><td>163.41</td><td>173.47</td><td>168.44</td><td>5.03</td></tr><tr><td></td><td>Base Pliocene</td><td>5.33</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>F8</td><td>X d-s Neogloboquadrina atlantica</td><td>9.23</td><td></td><td>52F-CC</td><td>54F-CC</td><td>337.84</td><td>347.37</td><td>342.61</td><td>4.77</td></tr><tr><td>F9</td><td>B Globorotalia cibaoensis</td><td>9.44</td><td>G. cibaoensis LOZ</td><td>54F-CC</td><td>56F-CC</td><td>347.37</td><td>356.70</td><td>352.04</td><td>4.66</td></tr><tr><td>F10</td><td>T Paragloborotalia mayeri</td><td>10.54</td><td>P. continuosa PRZ</td><td>58X-CC</td><td>59X-CC</td><td>366.22</td><td>378.93</td><td>372.58</td><td>6.36</td></tr><tr><td>F11</td><td>B Neogloboquadrina acostaensis</td><td>10.57</td><td></td><td>62X-CC</td><td>63X-CC</td><td>404.47</td><td>413.27</td><td>408.87</td><td>4.40</td></tr><tr><td></td><td>Base upper Miocene</td><td>11.65</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>F12</td><td>B Neogloboquadrina atlantica</td><td>11.76</td><td></td><td></td><td>&gt;64X-CC</td><td></td><td>&gt;427.40</td><td></td><td></td></tr><tr><td>F15</td><td>B Orbulina suturalis</td><td>15.12</td><td></td><td>395C-U1562B-14R-2, 12-17</td><td>395C-U1562B-14R-2, 12-17</td><td></td><td></td><td>&gt;475.66</td><td></td></tr><tr><td></td><td></td><td></td><td></td><td>395C-U1562C-3H-CC</td><td>395C-U1562C-4H-CC</td><td>24.62</td><td>34.32</td><td>29.47</td><td>4.85</td></tr><tr><td>F1</td><td>Bc Neogloboquadrina pachyderma (sin)</td><td>1.82</td><td>N. pachyderma PRZ</td><td>3H-CC</td><td>4H-CC</td><td>24.62</td><td>34.32</td><td>29.47</td><td>4.85</td></tr><tr><td>F2</td><td>B Globoconella inflata</td><td>2.06</td><td>G. inflata LOZ</td><td>7H-CC</td><td>8H-CC</td><td>54.20</td><td>63.78</td><td>58.99</td><td>4.79</td></tr><tr><td>F3</td><td>B Globigerina umbilicata</td><td>2.07</td><td></td><td>6H-CC</td><td>7H-CC</td><td>44.81</td><td>54.25</td><td>49.53</td><td>4.72</td></tr><tr><td>F4</td><td>T Neogloboquadrina atlantica</td><td>2.26</td><td>G. bulloides PRZ</td><td>10H-CC</td><td>12H-CC</td><td>82.65</td><td>101.75</td><td>92.20</td><td>9.55</td></tr><tr><td>F5</td><td>B Globigerina cariacoensis</td><td>2.26</td><td></td><td>14H-CC</td><td>15H-CC</td><td>120.71</td><td>129.79</td><td>125.25</td><td>4.54</td></tr><tr><td>F6</td><td>B Globoconella puncticulata</td><td>4.54</td><td>G. puncticulata/N. atlantica CRZ</td><td>21F-CC</td><td>22F-CC</td><td>159.88</td><td>164.51</td><td>162.20</td><td>2.31</td></tr></tbody></table>
tinctly lower depth in Hole U1562C, between Samples 7H-CC (54.20 m CSF-A) and 8H-CC (63.78 m CSF-A), but this is considered less reliable because it is based on the presence of a single specimen.

Sample 395C-U1562A-9H-CC (78.44 m CSF-A) yielded a very small residue in the >63 µm fraction, possibly because this part of the sediment drift was subject to winnowing, and contains just two specimens of *Neogloboquadrina atlantica*. Because this species is usually common up to its top occurrence (Poore and Berggren, 1975), these specimens are interpreted as probably reworked and the top occurrence datum (2.26 Ma) is placed between Samples 9H-CC (78.44 m CSF-A) and 10H-CC (88.05 m CSF-A). An even more complex picture occurs around the same depth in Hole U1562C, in which a series of samples spanning from Sample 10H-CC (82.65 m CSF-A) through 14H-CC inclusive (120.71 m CSF-A) have only few or rare planktonic foraminifers or are barren. In the same interval, quartz and rock fragments interpreted as ice-rafted debris (IRD) vary from dominant (Sample 11H-CC; 92.35 m CSF-A) to absent (Sample 12H-CC; 101.75 m CSF-A). Observations of the sediment in this interval (see *Lithostratigraphy*) reveal that IRD presence varies greatly on a decimeter scale, such that the paleontological core catcher samples must inevitably alias a complex stratigraphic pattern. In Hole U1562C, the top of *N. atlantica* is placed between Samples 10H-CC (82.65 m CSF-A) and 12H-CC (101.75 m CSF-A), and the intervening sample (11H-CC; 92.35 m CSF-A) is barren and dominated by IRD.

The bottom extent of frequent to dominant quartz and rock fragments is constrained in Hole U1562C to between Samples 14H-CC (120.71 m CSF-A) and 15H-CC (129.79 m CSF-A). In Hole U1562A, the lowest abundant quartz is in Sample 14H-CC (125.61 m CSF-A). These observations constrain the lowest recorded evidence for significant ice rafting in our samples.

The washed residue >63 µm of Sample 395-U1562C-15H-CC (129.79 m CSF-A) contains large numbers of foraminifer tests, many of which are infilled with a speckled light greenish gray to glossy black material and coated with a thin reddish orange rind with a waxy appearance (Figure F31). The greenish gray to glossy black material also occurs as free rounded pellets and subangular clasts. Preliminary shipboard investigation with scanning electron microscope-energy dispersive spectrometry (SEM-EDS) and XRD indicates that it is likely glauconite, and the reddish orange coatings appear to be an iron- and titanium-rich amorphous silica. This mineralization is interpreted as authigenic, suggesting that the foraminifers may have been exposed on the seafloor for extended periods before being mixed with fresh unaltered specimens and concentrated by seafloor currents. Glauconite and glauconite-infilled foraminifers occur sporadically through the rest of the succession below this level.

The base of the *Globoconella puncticulata/N. atlantica* Zone is marked by the base of *G. puncticulata* (4.54 Ma) between Samples 395C-U1562A-18H-CC (163.41 m CSF-A) and 19H-CC (173.47 m CSF-A) and at a similar depth in Hole U1562C between Samples 21F-CC (159.88 m CSF-A) and 22F-CC (164.51 m CSF-A). This event corresponds to the immigration and rapid dispersal of *G. puncticulata* across much of the Atlantic Ocean and Mediterranean Sea that is well constrained at 4.54 Ma in other sections (for discussion, see *Micropaleontology* in the Expedition 395 methods chapter [Parnell-Turner et al., 2025a]).

<figure><img src="image_37.png" /></figure>

**Figure F31.** Foraminifer residue >63 µm (395-U1562C-15H-CC; 129.79 m CSF-A). Shown is a mixture of relatively fresh looking foraminifers (white) and glauconite-infilled shells (greenish gray to black) with iron-/titanium-rich silica coatings (orange). Free glauconite pellets and sponge spicules also occur.
The interval from base *G. puncticulata* to Sample 395C-U1562A-52F-CC (337.84 m CSF-A) is relatively homogeneous in terms of planktonic foraminifer assemblages, with *N. atlantica* (sinistral), *G. bulloides*, and *Globigerina falconensis* generally common or abundant and *G. scitula* occurring sporadically. Scattered occurrences of specimens attributed to *Globorotalia cibaoensis* indicate an assignment to the *G. cibaoensis* Zone. *Orbulina universa* is consistently present, albeit in low numbers, which contrasts with its patchier occurrences at higher stratigraphic levels at the site.

A pronounced shift in the coiling direction of *N. atlantica* from dextral to sinistral dominance (going upcore) occurs between Samples 395C-U1562A-52F-CC (337.84 m CSF-A) and 54F-CC (347.37 m CSF-A) (Figure F32; Table T8). Although the species is very rare in the latter sample with just two specimens observed, both are dextral. The same sample is noteworthy in containing many large *O. universa*, which is much more common than it is anywhere else in the succession. The coiling shift is calibrated at 9.23 Ma based on the record of Aksu and Kaminski (1989) at Ocean Drilling Program (ODP) Site 646 in the Labrador Sea (see Micropaleontology in the Expedition 395 methods chapter [Parnell-Turner et al., 2025a]). *N. atlantica* is common or abundant in Samples 56F-CC (356.70 m CSF-A) through 64X-CC (427.40 m CSF-A), although it is dominated by the “primitive” morphotype that some authors prefer to recognize as *N. atlantica praeatlantica* (Foresi et al., 2002). Base *G. cibaoensis*, which marks the base of the *G. cibaoensis* Zone (9.44 Ma), is just below the coiling shift in *N. atlantica* and is located between Samples 54F-CC (347.37 m CSF-A) and 56F-CC (356.70 m CSF-A), but its relative rarity and the patchiness of its distribution gives the biohorizon low confidence.

The top of *Paragloborotalia mayeri* (10.54 Ma), marking the base of the *Paragloborotalia continuosa* Zone, occurs between Samples 395C-U1562A-58X-CC (366.22 m CSF-A) and 59X-CC (378.93 m CSF-A). The species is rare below its disappearance level despite being common to abundant lower in the succession in Samples 63X-CC (413.27 m CSF-A) and 64X (427.40 m CSF-A). This pattern contrasts with ODP Site 926 in the tropical Atlantic, where the biohorizon is calibrated astronomically at 10.54 Ma and the species is abundant up to its extinction level (Chaisson and Pearson, 1997). There are complex taxonomic and biochronologic questions surrounding this

<figure><img src="image_38.png" /><figcaption>**Figure F32.** *N. atlantica* coiling ratios, Site U1562. Error bars = 95% confidence intervals. The dextral to sinistral shift (calibrated at 9.23 Ma) is marked.</figcaption></figure>

**Table T8.** *N. atlantica* coiling direction count data, Site U1562. **Download table in CSV format.**
potentially useful datum (see discussion in Raffi et al., 2020). Specimens at Site U1562 closely resemble those illustrated as *P. mayeri* at Deep Sea Drilling Project (DSDP) Site 407 on the Reykjanes Ridge by Poore (1979), with distinctly curved sutures on the spiral side and highly arched apertures. Samples from Site U1562 were directly compared under the microscope with an assemblage from near the top occurrence at Site 926. Those from Site U1562 are on average smaller with fewer chambers and more strongly curved spiral sutures, but very similar specimens occur among the range of variation at Site 926. It is likely that the top occurrence on the Reykjanes Ridge records the same biological extinction as occurs in the tropics.

An upsection change from random to dextrally dominant coiling in *N. atlantica* occurs between Samples 395C-U1562A-59X-CC (378.93 m CSF-A) and 60X-CC (383.06 m CSF-A) (Figure F32). This change may be useful for regional correlation. The lowermost sample examined in the regular sedimentary succession, Sample 64X-CC (427.4 m CSF-A), contains *P. mayeri* and is assigned to the *P. mayeri* highest occurrence zone. It also contains *N. atlantica*.

Hole U1562B was cored with the RCB system from the lowermost part of the sedimentary succession into basement. After penetrating over 45 m into basalt, a substantial interval of sediment was encountered, comprising the whole of Section 14R-2. Sample 14R-2, 12–17 cm (475.66 m CSF-A), contains a well-preserved foraminifer assemblage that is significantly older than the lowermost sample examined from the sedimentary succession described above. Of particular note is the frequent presence of a globorotaliid species of uncertain affinity. The species bears a general resemblance to *Fohsella fohsi*, a tropical form from the same time interval, except that it is heavily encrusted and invariably has five chambers per whorl rather than the six typical of *E. fohsi*. Also present in the sample is rare *Trilobatus trilobus* (the only observed occurrence in Expedition 395 samples of this common low- to mid-latitude species) and questionable *Praeorbulina circularis*. Another peculiarity of the assemblage compared with all overlying samples is the absence of *Para-globorotalia* species. These indications suggest that the sediment pocket is distinctly older than the lowermost part of the regular sedimentary succession at the site, but it is difficult to specify how much older (see Age model).

## 6.3. Bolboforms

Bolboforms were studied in the same set of sample residues used for foraminifers. In Hole U1562C, bolboforms occur from Sample 27F-CC (184.88 m CSF-A) downward. In Hole U1562A, they occur in every sample studied from Sample 22F-CC (196.87 m CSF-A) downward. They are generally very rare in comparison to foraminifers and other particles but become markedly more abundant downcore. Being small, they are difficult to identify with the light microscope, so all specimens were transferred to SEM stubs and imaged using the shipboard Hitachi TM3000 desktop SEM before taxonomic assignment. A list of biohorizons is presented in Table T9.

Top *Bolboforma intermedia*, marking the base of the *Bolboforma costairregularis* Zone, could not be identified because of very scarce occurrences. The base of *B. intermedia*, marking the base of the *B. intermedia* Zone (8.18 Ma), is located tentatively between Samples 395C-U1562A-48F-CC and 50F-CC (318.91–328.49 m CSF-A). *Bolboforma metzmacheri* is also rare in the succession, with its base marking the base of the *B. metzmacheri* Zone (9.89 Ma), tentatively placed between Samples 56F-CC (356.70 m CSF-A) and 58X-CC (366.22 m CSF-A). The top of *Bolboforma sub-*

<table><caption>**Table T9.** Bolboform bioevents, Site U1562. B = bottom, T = top. LOZ = lowest occurrence zone, PRZ = partial range zone, TRZ = total range zone. **Download table in CSV format.**</caption><thead><tr><th>Biohorizon</th><th>Marker species</th><th>Age (Ma)</th><th>(Sub)zone base</th><th>Top core, section, interval (cm)</th><th>Bottom core, section, interval (cm)</th><th>Top depth CSF-A (m)</th><th>Bottom depth CSF-A (m)</th><th>Midpoint depth CSF-A (m)</th><th>±</th></tr></thead><tbody><tr><td></td><td></td><td></td><td></td><td>395C-U1562A-</td><td>395C-U1562A-</td><td></td><td></td><td></td><td></td></tr><tr><td>B3</td><td>Base Pliocene</td><td>5.33</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td></td><td>B Bolboforma intermedia</td><td>8.18</td><td>B. intermedia TRZ</td><td>48F-CC</td><td>50F-CC</td><td>318.91</td><td>328.49</td><td>323.70</td><td>4.79</td></tr><tr><td>B4</td><td>B Bolboforma metzmacheri</td><td>9.89</td><td>B. metzmacheri LOZ</td><td>56F-CC</td><td>58X-CC</td><td>356.70</td><td>366.22</td><td>361.46</td><td>4.76</td></tr><tr><td>B5</td><td>T Bolboforma subfragoris</td><td>10.82</td><td>B. capsula PRZ</td><td>59X-CC</td><td>60X-CC</td><td>378.93</td><td>383.06</td><td>381.00</td><td>2.06</td></tr><tr><td></td><td>Base upper Miocene</td><td>11.65</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr></tbody></table>
*fragoris*, which marks the base of the *Bolboforma capsula* Zone (10.82 Ma), is more confidently placed between Samples 59X-CC (378.93 m CSF-A) and 60X-CC (383.06 m CSF-A). Several bicamerate specimens of *B. subfragoris* were observed in Sample 61X-CC (395.04 m CSF-A).

The lowermost sample examined is Sample 395C-U1562B-14R-2, 12–17 cm, which was taken from the short section of sediment that occurs more than 45 m below the top of igneous basement (see **Planktonic foraminifers**). The bolboform assemblage in this sample is distinctly different from those taken from the regular succession above and contains *Bolboforma laevis* together with several specimens of *Bolboforma clodiusi* and the *Bolboforma reticulata* s.l. group. The latter species, which is the most abundant species in the sample, resembles the form illustrated as “*Bolboforma oblongireticulata*” by Spiegler (1999), which appears to be a nomen nudum because it was never formally described. If that identification is correct, the assemblage is most likely from the middle Miocene *Bolboforma compressispinosa* Zone of Spiegler (1999), although the nominate species of the zone was not found in the sample. If so, this observation would agree with the planktonic foraminifer and nannofossil evidence from the sediment pocket and could indicate a tentative age of ~12.33–12.43 Ma according to our recalibration of the short biostratigraphic range of “*Bolboforma oblongireticulata*” at ODP Site 982 reported in Spiegler (1999).

## 7. Physical properties

A range of whole-round, section-half, and discrete sample physical properties were measured on ~730 m of sediment core recovered from Holes 395C-U1562A, 395C-U1562B, and 395-U1562C and ~77 m of basement core recovered from Holes U1562A and U1562B (Table T10). Physical properties data were cleaned for half the response function corresponding to the instruments at the top and bottom of each section, and values deemed artifacts were removed from the respective figures (Table T11). All raw data are retained in the Laboratory Information Management System (LIMS) database.

<table><caption>**Table T10.** Physical properties measurement resolution, Site U1562. MSP = point MS, RSC = reflectance spectroscopy and colorimetry, PWL = *P*-wave logger, PWB = *P*-wave bayonet, TCON = thermal conductivity. * = some variability in the measurement resolution that is dependent on the core recovery and changes in lithology, NA = not applicable. **Download table in CSV format.**</caption><thead><tr><th>Hole</th><th>Lithology</th><th>GRA (cm)</th><th>MAD (m)</th><th>MS (cm)</th><th>MSP (cm)</th><th>NGR (cm)</th><th>RGB (cm)</th><th>RSC (cm)</th><th>PWL (cm)</th><th>PWC (m)</th><th>PWB (m)</th><th>TCON (m)</th></tr></thead><tbody><tr><td rowspan="4">395C-<br>U1562A</td><td>Sediment</td><td>2.5</td><td>~10</td><td>2.5</td><td>2.5</td><td>10</td><td>1</td><td>2.5</td><td>2.5</td><td>NA</td><td>NA</td><td>~10</td></tr><tr><td>Basalt</td><td>2.5</td><td>NA</td><td>2.5</td><td>2.5</td><td>10</td><td>1</td><td>2.5</td><td>NA</td><td>1 sample</td><td>NA</td><td>1 sample</td></tr><tr><td>Sediment</td><td>2.5</td><td>NA</td><td>2.5</td><td>2.0</td><td>10</td><td>1</td><td>2.0</td><td>2.5</td><td>~1 per core</td><td>NA</td><td>NA</td></tr><tr><td>Basalt</td><td>2.5</td><td>NA</td><td>2.5</td><td>2.0</td><td>10</td><td>1</td><td>2.0</td><td>2.5</td><td>~1 per core</td><td>NA</td><td>~10*</td></tr><tr><td rowspan="2">395-<br>U1562C</td><td>Sediment</td><td>2.5</td><td>NA</td><td>2.5</td><td>2.5</td><td>10</td><td>1</td><td>2.5</td><td>2.5</td><td>~1 per core</td><td>NA</td><td>~5–10</td></tr></tbody></table>

<table><caption>**Table T11.** Physical properties data cleaning, Site U1562. Indicated values are considered unrealistic and were removed from the presented figures. MSP = point MS, NA = not applicable. **Download table in CSV format.**</caption><thead><tr><th rowspan="2">Parameter (unit)</th><th rowspan="2">Edge effect removal (cm)</th><th colspan="2">Expedition 395</th><th>Expedition 395</th></tr><tr><th>Hole U1562A</th><th>Hole U1562B</th><th>Hole U1562C</th></tr></thead><tbody><tr><td>MS (WRMSL, IU)</td><td>10</td><td>&gt;750</td><td>&gt;1200</td><td>&gt;750</td></tr><tr><td>MSP (SHMSL, IU)</td><td>10</td><td>&gt;750</td><td>&gt;1200</td><td>&gt;750</td></tr><tr><td>GRA (WRMSL, g/cm³)</td><td>10</td><td>&lt;1.25, &gt;2</td><td>&lt;1 (0–430 m CSF-A), &lt;2 (430 m CSF-A to bottom of hole)</td><td>&lt;1.25, &gt;1.8</td></tr><tr><td>P-wave logger (m/s)</td><td>10</td><td>&lt;1450, &gt;1700</td><td>&gt;2000</td><td>&lt;1450, &gt;1900</td></tr><tr><td>RGB</td><td>5</td><td>&gt;160 (0–351 m CSF-A), &gt;180 (351–425 m CSF-A), &gt;200 (425 m CSF-A to bottom of hole)</td><td>NA</td><td>&gt;150</td></tr><tr><td>Color spectrometry (L*)</td><td>5</td><td>&gt;50 (0–240 and 270–340 m CSF-A)</td><td>NA</td><td>NA</td></tr><tr><td>Color spectrometry (a*)</td><td>5</td><td>&lt;8</td><td>NA</td><td>&gt;7</td></tr><tr><td>Color spectrometry (b*)</td><td>5</td><td>less than –5</td><td>NA</td><td>&gt;60</td></tr></tbody></table>
**7.1. Whole-round measurements**

Variations in sedimentary physical properties in Hole U1562C are very similar to those measured in the overlapping stratigraphic interval of Hole U1562A (Figures F33, F34). The sediments in the uppermost 130 m gradually increase downhole in gamma ray attenuation (GRA) bulk density, MS, and NGR with superimposed meter-scale oscillations. These parameters drop sharply at 130 m CSF-A. Below 130 m CSF-A, bulk densities stay relatively constant with small variations around 1.6 g/cm³, and MS and NGR show a more variable pattern. Relatively large amplitude variations (hundreds of instrument units for MS and tens of counts per second for NGR) to ~350 m CSF-A, below which both parameters show lower values. Between 180 and 300 m CSF-A, the oscillations in MS and NGR are most prominent and occur on a scale of ~20 m. Whole-Round Multisensor Logger (WRMSL) P-wave velocity ($V_p$) values increase slightly downhole and average around 1500 m/s.

In Hole U1562B, voids and gaps between the core and liners in the basalt sections make the interpretation of physical properties profiles less straightforward (Figure F35). Nevertheless, intervals of higher MS seem to correspond to slightly lower values in bulk density and NGR. Measured values in the sedimentary interval (Cores 2R-4R) are comparable with the physical properties values for the deepest sediments in Hole U1562A.

**7.2. Split core measurements**

The point MS (MSP) data show relative variations similar to those in the WRMSL MS data, and the absolute values for the sediments are alike, with the MSP values for the basalts slightly higher and lower in their relative extrema, probably because the WRMSL data integrate the volume of the whole core section (Figures F33, F34, F35). The changes in color reflectance properties in the

<figure><img src="image_39.png" /><figcaption>**Figure F33.** Physical properties measurements. Hole U1562A. cps = counts per second.</figcaption></figure>
<figure><img src="image_40.png" /><figcaption>**Figure F34.** Physical properties measurements, Hole U1562C. cps = counts per second.</figcaption></figure>

<figure><img src="image_41.png" /><figcaption>**Figure F35.** Physical properties measurements, Hole U1562B. cps = counts per second.</figcaption></figure>
sediments of Holes U1562A and U1562C are divided into stratigraphic intervals similar to those in the WRMSL profiles (Figures F36, F37). Two brownish layers (9 and 7 m thick) with higher R, a*, and b* values occur toward the top of the holes (0–30 m CSF-A), below which depth color changes are dampened and the general color trends to darker to 130 m CSF-A. The interval between 130 and 350 m CSF-A has pronounced color cycles of varying thicknesses between lighter and darker intervals (submeter to multimeter scales). Just above the contact with basalt (350–430 m CSF-A), the sediments are noticeably lighter in color than the sediments above.

The presence of significant voids and uneven surfaces in the basalt sections of Hole U1562B leads to noisy color reflectance data (Figure F38). In the basement, the sedimentary and peperite units show up clearly in color records, with higher R, G, B, a*, and b* values (Figure F15). The L* reflectance record shows intervals of lower values, but a systematic relationship with basalt morphology is not observed.

## 7.3. Discrete measurements

### 7.3.1. P-wave velocity

$V_p$ caliper (PWC) values (from measurements made in the x-direction, perpendicular to the core long axis) for sediments from Hole U1562B are about 1700 m/s, and for basalts they vary between

<figure><img src="image_42.png" /><figcaption>**Figure F36.** Archive-half colorimetry and reflectance measurements, Hole U1562A.</figcaption></figure>
4725 and 6053 m/s (Figure F35). Sedimentary $V_p$ values in Hole U1562C average around 1500 m/s (Figure F34). One point measured in Section 395-U1562C-16H-6, 53 cm (137.65 m CSF-A), shows a higher value of 1798 m/s, which is consistent with the higher velocity measurements measured using the WRMSL in this interval. This observation might indicate condensation at a lithologic transition that might also be a disconformity (see Lithostratigraphy and Age model).

### 7.3.2. Moisture and density

Moisture and density (MAD) samples were measured on sediment cores from Hole U1562A at approximately one per 10 m. Bulk density values are shown in Figure F33 alongside the WRMSL bulk density estimates. MAD estimates of bulk density values in Hole U1562A range 1.4–1.7 g/cm³ and are in good agreement with GRA bulk density estimates from the WRMSL. Porosity ranges 63–81 vol% with an average of 70 vol% and a slightly decreasing trend downhole from around 80 to 65 vol%. Grain density varies from 2.6 to 2.9 g/cm³ with an average of 2.7 g/cm³ and shows a decreasing trend from around 2.9 to 2.6 g/cm³.

### 7.3.3. Thermal conductivity

Thermal conductivity measurements were made on working-half sections at a variable resolution for the different holes (Table T10). Thermal conductivity is typically 0.75–1.20 W/(m·K) for the sediments from Holes U1562A and U1562C and 1.40–1.80 W/(m·K) for Hole U1562B. Values slightly increase with depth for the sedimentary units and are relatively constant for the basement

<figure><img src="image_43.png" /><figcaption>**Figure F37.** Archive-half colorimetry and reflectance measurements, Hole U1562C.</figcaption></figure>
<figure><img src="image_44.png" /><figcaption>**Figure F38.** Archive-half colorimetry and reflectance measurements, Hole U1562B.</figcaption></figure>

rocks. Thermal conductivity measurements of the sediments are combined with downhole formation temperature measurements to estimate heat flow (see **Downhole measurements**; Figure F57).

**8. Stratigraphic correlation**

The stratigraphic correlation reported here includes the main sedimentary targets of coring from Holes 395C-U1562A and 395-U1562C. Information from Hole U1562A was used to inform the position of the first core for Hole U1562C. MS data from whole-round measurements were used for near real-time correlation because they often reveal strong contrasts between lithologic sequences. These data were obtained shortly after the core is recovered on deck at 5.0 cm resolution using the Special Task Multisensor Logger (STMSL) to guide operational decisions. The whole-round MS data collected at 2.5 cm resolution using the WRMSL were used to construct the final splices. An overview of the MS data from Holes U1562A and U1562C and the wireline log data from Hole 395C-U1562B are presented in Figure F39.

**8.1. Correlation between holes**

Core 395-U1562C-1H recovered the mudline plus a length of 5.37 m, and this initial offset allowed filling gaps in recovery in Hole U1562A. Correlation was achieved without gaps through Cores 395C-U1562A-16H (144.63 m CSF-A; 155.125 m core composite depth below seafloor, Method A
[CCSF-A]) and 395-U1562C-17F (144.22 m CSF-A) (Figure F40). The lower extent of these cores was too close to alignment to be able to tie on to any of the next cores, leading to a correlation gap. Based on the pattern of MS variability and correlation with the downhole wireline logging MS data collected in Hole U1562B, the gap is estimated to be approximately 1 m. Similar small gaps can be

<figure><img src="image_45.png" /><figcaption>**Figure F39.** WRMSL and wireline logging MS, Site U1562.</figcaption></figure>

<figure><img src="image_46.png" /><figcaption>**Figure F40.** Splice for 0–160 m CCSF-A, Site U1562. Cores included in the splice are noted, where C1 = Core 395-U1562C-1H.</figcaption></figure>
found between Cores 395-U1562C-20F and 395C-U1562A-18H and between Cores 395-U1562C-22F and 395C-U1562A-19H (Figure F41). Despite the small gaps, this interval can still be tied with some confidence based on the broad cyclical patterns and the comparison with wireline logging MS data from Hole U1562B. In Cores 395-U1562C-19H through 35F and 395C-U1562A-25F through 35F, ties can be made to ~280 m CCSF-A (Figure F42). Below Core 395C-U1562A-35F, correlation between holes becomes difficult, probably because of the presence of disrupted sedimentary sequences (see Lithostratigraphy).

**8.2. Construction of the splice**

The continuous splice for the uppermost 155 m CCSF-A includes Holes U1562A and U1562C (Figure F40; Table T12). An appended splice is further extended to Core 395C-U1562A-35F by estimating the presence and magnitude of several small gaps (<1 m) (Figure F42). Core catcher sections were not included in the splice, and splice figures presented here do not include data collected in the core catcher sections.

<figure><img src="image_47.png" /></figure>

**Figure F41.** Splice for 155–195 m CCSF-A, Site U1562. Cores included in the splice are noted, where A16 = Core 395C-U1562A-16H. Several gaps (gray bars) prevent a full splice in this interval.
<figure><img src="image_48.png" /></figure>

**Figure F42.** Splice for 150–280 m CCSF-A, Site U1562. Cores included in the splice are noted, where A16 = Core 395C-U1562A-16H.

**Table T12.** Splice table, Site U1562. Download table in CSV format.

# 9. Paleomagnetism

## 9.1. Shipboard measurements

Shipboard paleomagnetic investigations were conducted on archive-half sections from Holes 395C-U1562A, 395C-U1562B, and 395-U1562C (Figure F43; see Paleomagnetism in the Expedition 395 methods chapter [Parnell-Turner et al., 2025a]). For sediments from Hole U1562A, five demagnetization steps (0, 10, 15, 20, and 25 mT) at 2.5 cm spacing were performed, and for Hole U1562C four steps (0, 10, 15, and 20 mT) were adopted, using a resolution of 2.5 or 5 cm. For basalts from Hole U1562B, five steps of demagnetization (0, 10, 15, 20, and 25 mT) at 2 cm spacing were adopted.

We used the directional data from archive halves measured after in-line alternating field (AF) demagnetization step (maximum demagnetization step of 20 or 25 mT) to determine magnetic polarities in each hole. Directional data were analyzed using Zijderveld diagrams (Zijderveld, 1967), and the characteristic remanent magnetization (ChRM) direction(s) were calculated using principal component analysis (PCA) (Kirschvink, 1980) using PuffinPlot software (Version 1.4.1; Lurcock and Florindo, 2019).

## 9.2. Demagnetization behavior of sedimentary rocks

After the removal of an overprint up to 10 mT, stepwise AF demagnetization performed up to 20 or 25 mT successfully isolated a stable ChRM directed to the origin of the Zijderveld plot, even if not completely demagnetized (Figure F44). Normal (Figure F44A, F44D) and reversed (Figure
**F44B, F44E)** polarities were identified both in Holes U1562A and U1562C. In some cases, the natural remanent magnetization (NRM) was fully demagnetized within the 10 mT step (Figure **F44C, F44F**).

In Hole U1562A, NRM intensity varies from $4.8 \times 10^{-5}$ to 4.3 A/m (average = 0.2 A/m). In Hole U1562C, NRM intensity ranges $4.9 \times 10^{-3}$ to 2.21 A/m (average = 0.23 A/m) (Figure F45).

In Hole U1562A, point MS obtained from section halves (see **Physical properties**) ranges 2.7-664.2 IU (average = 228.3 IU) (Figure F45). Three measurement points in interval 58X-1, 22.5-27.5 cm, are greater than 1000 IU and correspond to three large (>2 cm) basaltic clasts (not shown). In Hole U1562C, MS varies from 0.4 to 755.7 IU (average = 248.1 IU) (Figure F46).

Both NRM and MS show considerable variability with depth (Figures F45, F46, F47), most likely due to changes in carbonate and silica content in sedimentary units. At 120-350 m CSF-A in Hole U1562A and 120-300 m CSF-A in Hole U1562C, both MS and NRM show a cyclicity that may reflect changes in carbonate content (see **Lithostratigraphy**). Below 350 m CSF-A in Hole U1562A, both NRM intensity and MS decrease considerably. Variations in inclination reflect changes in the magnetic polarities. Intervals of soft-sediment deformation (see **Lithostratigraphy**), which hamper magnetostratigraphic interpretation, are highlighted as yellow bands in Figures F45 and F46. Normal polarities (in black) are characterized by positive inclinations with short secular variations around values similar to the present-day field at Site U1562.

<figure><img src="image_49.png" /></figure>

**Figure F43.** Inclination, Holes U1562A–U1562C. In-line measurements collected with SRM on archive halves at 25 mT (black) and 20 mT (gray) demagnetization steps.
**9.3. Demagnetization behavior of basalts**

The igneous rocks in Hole U1562B consist of pillow basalts and basalt flows (see Igneous petrology). Typical examples of demagnetization behavior are shown in Figure F48. After the removal of an initial overprint at 10–15 mT, usually a single component of magnetization can be isolated. AF demagnetization mainly shows two types of behavior with total magnetization loss before 20 mT (i.e., soft magnetization behavior; Figure F48B) or no significant loss of magnetization at 25 mT (i.e., hard magnetization behavior; Figure F48A, F48C, F48D). Most of the basalts show normal polarity (Figure F48D).

<figure><img src="image_50.png" /></figure>

**Figure F44.** Demagnetization behaviors of sediments, Holes U1562A and U1562C. A, D. Normal polarity samples. B, E. Reversed polarity samples. C, F. Samples showing early decay at 10 mT. Declination and inclination of remanent magnetization at progressive demagnetization steps are displayed on both stereographic projection and Zijderveld diagrams (Zijderveld, 1967). Intensity of remanent magnetization is plotted against treatment value. Zijderveld diagrams: solid symbols = declination, open symbols = inclination. Stereographic plots: solid symbols = positive (down-pointing) inclination, open symbols = negative (up-pointing) inclination.
The transition from sedimentary to igneous rocks occurs at ~430 m CSF-A with considerable change in NRM intensity and two orders of magnitude increase in MS (Figure F49).

**9.4. Magnetostratigraphy**

The magnetostratigraphy of Site U1562 is based on the correlation of the polarity assigned to the archive-half cores from Hole U1562A using inclinations after 25 mT demagnetization and the polarities reported in the reference geomagnetic polarity timescale (GPTS) (Table T13). Importantly, the magnetic events recognized in Hole U1562A (Figure F45) are also identified in Hole U1562C (Figure F46). In sections where soft-sediment deformation is present, the inclination record is most likely disturbed and not interpretable in terms of magnetic polarities.

The magnetostratigraphic data from Hole U1562A were correlated to the GPTS (Ogg, 2020) and plotted along with the tie points from the microfossil ages (see **Age model**). A succession of 14 normal and 14 reversed intervals was recognized (Figure F47).

The boundary between the Brunhes and Matuyama Chrons was interpreted at ~13 m CSF-A (0.773 Ma), and the transition from the Matuyama to Gauss Chrons was interpreted at ~108 m CSF-A (2.595 Ma) (Table T13).

<figure><img src="image_51.png" /></figure>

**Figure F45.** Paleomagnetic measurements, Hole U1562A. Yellow bands = intervals showing soft-sediment deformation. NRM and inclination: red = NRM, black = NRM after 25 mT AF demagnetization. Magnetic polarity interpretation of inclination: n = normal, r = reversed, gray = depth for which a polarity interpretation was not unequivocal, or there was no recovery.
<figure><img src="image_52.png" /></figure>

**Figure F46.** Paleomagnetic measurements, Hole U1562C. Yellow bands = soft-sediment deformation. NRM and inclination: red = NRM, black = NRM after 20 mT AF demagnetization. Magnetic polarity interpretation of inclination: n = normal, r = reversed, gray = depth for which a polarity interpretation was not unequivocal.

<figure><img src="image_53.png" /></figure>

**Figure F47.** Paleomagnetic measurements from sediments, Hole U1562B. NRM and inclination: red = NRM, black = after 25 mT AF demagnetization.
<figure><img src="image_54.png" /></figure>

**Figure F48.** Demagnetization behaviors of basalts, Hole U1562B. A. Normal polarity sample. B. Normal polarity but a magnetization decaying at 15 mT. C. Normal polarity and a magnetization not decaying before 25 mT. D. Example of where it is difficult to isolate the ChRM and a polarity is not recognized. Declination and inclination of remanent magnetization at progressive demagnetization steps are displayed on both stereographic projection and Zijderveld diagrams (Zijderveld, 1967). Intensity of remanent magnetization is plotted against the treatment value. Zijderveld diagrams: solid symbols = declination, open symbols = inclination. Stereographic plots: solid symbols = positive (down-pointing) inclination, open symbols = negative (up-pointing) inclination.

<figure><img src="image_55.png" /></figure>

**Figure F49.** Paleomagnetic measurements, Hole U1562B. NRM and inclination: red = NRM, black = after 25 mT AF demagnetization.
<table><caption>**Table T13.** Paleomagnetic age datums, Hole U1562A and U1562C. n = normal, r = reverse. Base of magnetic polarities and sections are shown in Figures F45 and F46. Polarity subchron and base ages follow Ogg (2020). **Download table in CSV format.**</caption><thead><tr><th>Magnetic polarity</th><th>Magnetic polarity base CSF-A (m)</th><th>Core, section</th><th>Magnetic polarity</th><th>Magnetic polarity base CSF-A (m)</th><th>Core, section</th><th>Polarity subchron</th><th>Base of chron/ subchron (Ma)</th></tr></thead><tbody><tr><td></td><td></td><td>395C-U1562A-</td><td></td><td></td><td>395-U1562C-</td><td></td><td></td></tr><tr><td>n1</td><td>13.43</td><td>3H-2</td><td>n1</td><td>15.20</td><td>3H-1</td><td>C1n (Brunhes)</td><td>0.773</td></tr><tr><td>r1</td><td>18.85</td><td>3H-5</td><td>r1</td><td>20.50</td><td>3H-4</td><td>C1r.1r (Matuyama)</td><td>0.990</td></tr><tr><td>n2</td><td>20.58</td><td>3H-7</td><td>n2</td><td>22.40</td><td>3H-5</td><td>C1r.1n (Jaramillo)</td><td>1.070</td></tr><tr><td>r2</td><td>28.83</td><td>4H-6</td><td>r2</td><td>31.00</td><td>4H-5</td><td>C1r.3r</td><td>1.775</td></tr><tr><td>n3</td><td>34.73</td><td>5H-3</td><td>n3</td><td>35.60</td><td>6H-1</td><td>C2n (Olduvai)</td><td>1.934</td></tr><tr><td>r3</td><td>48.00</td><td>6H-6</td><td>r5</td><td>48.70</td><td>7H-3</td><td>C2r.1r</td><td>2.116</td></tr><tr><td>n4</td><td>48.73</td><td>6H-6</td><td>n5</td><td>49.20</td><td>7H-4</td><td>C2r.1n (Feni)</td><td>2.140</td></tr><tr><td>r4</td><td>108.15</td><td>13H-2</td><td>r6</td><td>101.40</td><td>13H-1</td><td>C2r.2r (Matuyama)</td><td>2.595</td></tr><tr><td>n5</td><td>137.71</td><td>16H-2</td><td>n7</td><td>137.40</td><td>16H-6</td><td>C2An.3n</td><td>3.596</td></tr><tr><td>r6</td><td>153.73</td><td>17H-7</td><td>r7</td><td>153.70</td><td>20F-3</td><td>C2Ar</td><td>4.187</td></tr><tr><td>n7</td><td>176.44</td><td>20H-3</td><td>n9</td><td>175.70</td><td>26F-1</td><td>C3r.4n (Thvera)</td><td>5.235</td></tr><tr><td>r7</td><td>207.58</td><td>25H-2</td><td>r9</td><td>207.60</td><td>32F-4</td><td>C3r (Gilbert)</td><td>6.023</td></tr><tr><td>n8</td><td>228.40</td><td>29H-3</td><td>n10</td><td>229.00</td><td>37F-2</td><td>C3An.2n</td><td>6.727</td></tr></tbody></table>

# 10. Geochemistry and microbiology

Cores taken during Expedition 395C (Holes U1562A and U1562B) were analyzed for headspace gas, IW chemistry, and bulk sediment/basalt geochemistry. Cores taken during Expedition 395 (Hole U1562C) were analyzed for bulk sediment geochemistry. The geochemistry of basalts at Site U1562 is described in **Igneous petrology**. Headspace gas analyses were conducted on cores from Holes U1562A and U1562B; methane concentrations are low and range ~0 to 3 ppmv. Ethane was absent in all holes. IW calcium ion ($Ca^{2+}$) concentrations are highest near the sediment/water and sediment/basement interfaces. Magnesium ion ($Mg^{2+}$) concentrations display a generally decreasing trend with depth, with a small increase at the sediment/basement interface. Sulfate ion ($SO_4^{2-}$) concentrations have seawater-like values at the top and bottom of the sedimentary sequence and a minimum around 250 m CSF-A. $CaCO_3$ shows large variability but generally increases downcore, trending from ~0 to 33 wt% in the uppermost 100 m to ~83 wt% near the sediment/basement interface. Bulk sediment generally exhibits low total organic carbon (TOC), total nitrogen (TN), and total sulfur (TS) content.

## 10.1. Volatile hydrocarbons

Methane concentrations in the sedimentary section of Site U1562 (Holes U1562A and U1562B) increase from 0.4 ppmv at the sediment/water interface to a peak of 2.7 ppmv at 317.2 m CSF-A and then drop back to 0 ppmv at the sediment/basement interface (Figure F50). The slightly increased methane concentrations and the absence of ethane in the middle part of the sedimentary sequence suggest increased biogenic methane gas production and that thermogenic gas sources are unlikely.

## 10.2. Interstitial water chemistry

A total of 66 IW samples were squeezed from 5 or 10 cm long whole-round samples from 0.95 to 427.3 m CSF-A in Hole U1562A (Cores 1H–64X). One additional IW sample was collected from Section 395C-U1562B-14R-2, 17–27 cm, from an intercalated sediment layer in the basalt basement at 475.71 m CSF-A. Selected data acquired from analysis of IW in Holes U1562A and U1562B are shown in Figure F51. pH displays little variation throughout the sedimentary section (7.69 ± 0.07). Alkalinity varies from near seawater values at the top (Sample 395C-U1562A-1H-1, 95–100 cm; 3.0 mM) and bottom (Sample 64X-4, 142–152 cm; 3.6 mM) of the sediment to high values at 223.15 m CSF-A (e.g., Sample 28F-2, 145–150 cm; 7.9 mM). IW $Mg^{2+}$ concentrations range 45.9–54.0 mM. $Mg^{2+}$ concentrations are highest (~50 mM) at the top and bottom of the sedimentary sequence, with the lowest $Mg^{2+}$ concentration (45.8 mM) occurring at 288.97 m CSF-A (Sample 44F-2, 146–151 cm). $SO_4^{2-}$ concentrations range 18.5–28.9 mM with the highest values
observed at the top and bottom of the sediments. SO₄²⁻ concentrations are also high in the intercalated basalt-sediment Sample 395C-U1562B-14R-2, 17–27 cm (28.9 mM). Ca²⁺ concentrations range 6.3–10.6 mM, with the lowest concentrations in the middle part of the sedimentary sequence. Sr²⁺ concentrations range from 84.9 µM at 0.95 m CSF-A to 154.3 µM at 425.34 m CSF-A; they generally increase toward the bottom of the sediments but decrease to 87.7 µM at 475.71 m CSF-A in Section 14R-2.

## 10.2.1. Bulk sediment geochemistry

### 10.2.1.1. Carbonate, nitrogen, carbon, and sulfur

Discrete sediment samples (n = 76) were collected from squeeze cake residues and working-half sections during sediment description for Cores 395C-U1562A-1H through 64X (0.95–427.3 m CSF-A), 395C-U1562B-14R (475.71 m CSF-A), and 395-U1562C-3H through 50F (15.39–284.12 m CSF-A) and analyzed for total carbon (TC), TN, and total inorganic carbon (TIC). For Hole U1562C, sedimentary TS was also analyzed. TOC content and CaCO₃ weight percent were subsequently calculated from TIC and TC measurements. CaCO₃ varies from 0.04 to 82.9 wt%, with the highest content at 475.71 m CSF-A in the intercalated sediments from Section 395C-U1562B-14R-2, 17–27 cm (bottom sample in Figure F52). The sampling strategy for CaCO₃ analyses (and as a result carbon, nitrogen, and sulfur analyses) differed between the holes. For Holes U1562A and U1562B, sediment was collected from the squeeze cake residues and was therefore sampled independent of lithology. No IW samples were collected for Hole U1562C; therefore, additional sediment samples were chosen so that the resulting geochemical information (e.g., CaCO₃ content) could be used to aid in lithologic description. The apparent offset in the CaCO₃ content

<figure><img src="image_56.png" /><figcaption>**Figure F50.** Composite gas analyses of methane concentrations, Holes U1562A and U1562B.</figcaption></figure>

<figure><img src="image_57.png" /><figcaption>**Figure F51.** IW pH, alkalinity, and concentrations of selected ions, Holes U1562A and U1562B.</figcaption></figure>
<figure><img src="image_58.png" /><figcaption>**Figure F52.** CaCO₃ and TOC from IW residues, Holes U1562A–U1562C. Sediment samples from Hole U1562C were selected from working halves to aid in sediment description.</figcaption></figure>

between the two holes thus reflects the sampling bias and variable sedimentary CaCO₃ content in different lithologic layers, not a general difference in CaCO₃ content between the two holes. TOC is low (<1.21 wt%) and averages 0.38 ± 0.23 wt%. Four analyses for C and N fall outside of the upper quartile of data (above 2 wt%) and were excluded from the interpretation. TN is also very low (range = 0–0.08 wt%). TS was only measured for Hole U1562C (range = 0–1.09 wt%).

### 10.2.2. Microbiology

Microbiological sampling of sediments from Holes U1562A and U1562C was focused on collecting material for culture-independent approaches. A total of 49 sediment samples from Hole U1562A and 31 sediment samples from Hole U1562C, each 5 cm³, were collected with a sterile cut-end syringe. A total of 13 whole-round samples of hard rock were collected from Hole U1562B for shore-based microbiological analyses.

## 11. Downhole measurements

Details on tools and logging procedures can be found in **Downhole measurements** in the Expedition 395 methods chapter (Parnell-Turner et al., 2025a); only hole-specific procedures are detailed here. Downhole logging operations at Site U1562 were conducted in Hole 395C-U1562B, which was logged with the triple combo tool string (Magnetic Susceptibility Sonde [MSS], High-Resolution Laterolog Array [HRLA], Accelerator Porosity Sonde [APS], Hostile Environment Litho-Density Sonde [HLDS], and Hostile Environment Natural Gamma Ray Sonde [HNGS]), FMS-sonic tool string (FMS, Dipole Sonic Imager [DSI], General Purpose Inclinometry Tool [GPIT], and HNGS), UBI tool string (UBI, GPIT, and HNGS), and VSI tool string (VSI and HNGS) (Tables T14, T15). During coring in Hole 395C-U1562A, formation temperature measurements were acquired at four locations (Cores 4H, 7H, 10H, and 13H) using the APCT-3 tool (Table T16).

### 11.1. Logging procedure and log data processing and quality control

After coring operations were completed in Hole U1562B, the hole was cleaned and the pipe was raised to 89 m DSF (86 m WSF). The heavy mud used for drilling was then replaced with seawater. The triple combo tool string was deployed first and acquired a downhole log (Data Set 010LUP), a repeat uphole log (Data Set 011LUP) from 136 to 559 m WSF, and an uphole log to the seafloor (Data Set 017PUP). During the downhole logging pass, the calipers were closed and the APS was turned off; therefore, no APS or HLDS data were acquired in this logging pass. The FMS-sonic tool string was deployed and acquired a downhole log (Data Set 032PUP) with the calipers closed (no FMS image log acquired), a repeat uphole log from 419 to 558 m WSF (Data Set 033PUP), and a main uphole log (Data Set 034PUP) along the entire open hole (0–558 m WSF). The quality of the Vp from the monopole transmitter was deemed acceptable for the basement interval (426–545 m WSF) by the Lamont-Doherty Earth Observatory Borehole Research Group (LDEO-BRG), but
it was deemed poor in the sediment section, so $V_p$ data for depths above 426 m WSF are not discussed here. The dipole shear velocities were deemed to be of good quality in the sediment section (~85–426 m WSF) and are discussed here. The third tool string deployed was the VSI tool string. A brief uphole VSI logging pass was performed from 81 to 113 m WSF to depth match the station depths to the other logging tools. Seismic data from four VSI stations were acquired at 556.6, 459.4, 428.5, and 420 m WSF. The final logging pass in Hole U1562B was the UBI tool string. An initial uplog (Data Set 050LUP) was acquired without the UBI switched on to collect a gamma log for depth matching (408–553 m WSF). Two more uphole logs were conducted, one from 410 to 553 m WSF (Data Set 051LUP) and another from 0 to 407 m WSF (Data Set 052LUP), to acquire acoustic borehole image logs with the UBI. Because of enlargement of Hole U1562B in the sedimentary section (0–426 m WSF), the UBI did not acquire a good quality acoustic image log above the basement.

The gamma log of the triple combo tool string uphole log (Data Set 017PUP) is used as the reference log for depth matching all logging data from Hole U1562B. Once depth matched, all logging data were depth shifted to a seafloor depth of 2015 m WMSF (0.5 m difference from the driller's depth of 2014.5 m drilling depth below rig floor [DRF]), which was determined by a step in the gamma log from the uphole log of the triple combo tool string (Data Set 017PUP). During logging operations, the wireline heave compensator (WHC) was used to counter the 0.25–0.5 m of ship heave.

<table><caption>**Table T14.** Logging passes in Hole 395C-U1562B and APCT-3 in situ formation temperature measurements in Hole 395C-U1562A. NA = not applicable. **Download table in CSV format.**</caption><thead><tr><th>Hole</th><th>Tool string</th><th>Tool list</th><th>Logging pass</th><th>Logging data reference</th><th>From depth WSF (m)</th><th>To depth WSF (m)</th><th>Pipe depth WSF (m)</th><th>Notes</th></tr></thead><tbody><tr><td>395C-U1562A</td><td>APCT-3</td><td>Formation temperature</td><td>NA</td><td>NA</td><td>21</td><td>116</td><td>NA</td><td>4 measurements acquired</td></tr><tr><td rowspan="5">U1562B</td><td rowspan="3">Triple combo</td><td rowspan="3">MSS-B/HRLA/APS/HLDS/HNGS</td><td>Downlog</td><td>010LUP</td><td>0</td><td>559</td><td>86</td><td>Caliper closed</td></tr><tr><td>Repeat (uplog)</td><td>011LUP</td><td>136</td><td>559</td><td>86</td><td>Recorded open hole</td></tr><tr><td>Main (uplog)</td><td>017PUP</td><td>0</td><td>559</td><td>86</td><td>Reference pass</td></tr><tr><td>VSI</td><td>VSIT/HNGS</td><td>NA</td><td>NA</td><td>81</td><td>113</td><td>86</td><td>4 stations acquired</td></tr><tr><td>FMS-sonic</td><td>FMS/DSI-2/GPIT/HNGS</td><td>Downlog</td><td>032PUP</td><td>0</td><td>485</td><td>86</td><td>Caliper closed</td></tr><tr><td rowspan="4">UBI</td><td rowspan="4"></td><td rowspan="4"></td><td>Repeat (uplog)</td><td>033LUP</td><td>419</td><td>558</td><td>86</td><td>Recorded open hole</td></tr><tr><td>Main (uplog)</td><td>034PUP</td><td>0</td><td>558</td><td>86</td><td></td></tr><tr><td>Uplog</td><td>052LUP</td><td>408</td><td>553</td><td>86</td><td>No image</td></tr><tr><td>Uplog</td><td>051LUP</td><td>410</td><td>553</td><td>86</td><td></td></tr><tr><td></td><td></td><td></td><td>Downlog</td><td>050LUP</td><td>0</td><td>407</td><td>86</td><td></td></tr></tbody></table>

<table><caption>**Table T15.** Downhole logging units, Hole U1562B. **Download table in CSV format.**</caption><thead><tr><th>Logging unit</th><th>Hole 395C-U1562B depth WMSF (m)</th><th>Lithology</th></tr></thead><tbody><tr><td>L1a</td><td>0–86</td><td>Sediment</td></tr><tr><td>L1b</td><td>86–136</td><td>Sediment</td></tr><tr><td>L2a</td><td>136–305</td><td>Sediment</td></tr><tr><td>L2b</td><td>305–350</td><td>Sediment</td></tr><tr><td>L3</td><td>350–426</td><td>Sediment</td></tr><tr><td>L4</td><td>426–560</td><td>Basalt</td></tr></tbody></table>

<table><caption>**Table T16.** APCT-3 measurements, Hole U1562A. **Download table in CSV format.**</caption><thead><tr><th>Section</th><th>Depth DSF (m)</th><th>Formation temperature (°C)</th></tr></thead><tbody><tr><td>395C-U1562A-4H</td><td>30.5</td><td>4.27</td></tr><tr><td>7H</td><td>59</td><td>5.37</td></tr><tr><td>10H</td><td>79</td><td>6.46</td></tr><tr><td>13H</td><td>116</td><td>7.34</td></tr></tbody></table>
The borehole diameter was enlarged in the sediment section of Hole U1562B, generally between 13 and 17 inches, which is larger than bit size (~9.875 inches). Hole enlargement affects most measurements, especially those acquired with tools that require eccentricization and a good contact to the borehole wall. In the basement, the hole size is mostly close to the bit size with only short, localized enlargements.

Image log quality is mostly poor for both the acoustic and resistivity image logs in the sedimentary portion of Hole U1562B but is of higher quality in the basement section (>426 m WMSF). FMS caliper data show the hole is ovalized at 135–240 m WMSF, with shorter intervals of complete borehole widening to diameters of ~14.5 inches. From ~240 to 426 m WMSF, the hole is enlarged to diameters of ~15 inches. In the basement section, Hole U1562B has a diameter in good agreement with bit size (~9.875 inches) with only slight widening of the hole diameter between 464 and 476 m WMSF.

## 11.2. Logging units

Four logging units (Unit L1 = 0–136 m WMSF; Unit L2 = 136–350 m WMSF; Unit L3 = 350–426 m WMSF; Unit L4 = 426–560 m WMSF) are defined for Hole U1562B based on downhole logging responses (Figure F53). Logging subunits are defined in Unit L1 to account for logging in drill pipe and open hole and in Unit L2 based on further variations in the MS and shear wave velocity ($V_s$).

### 11.2.1. Logging Unit L1

Depth: 0–136 m WMSF

Logging Unit L1 starts at the seafloor, and its boundary with Unit L2 is defined by an increase in gamma radiation at ~136 m WMSF. Despite the drill pipe repressing the gamma measurements in the upper portion of Unit L1 (Subunit L1a), the overall character of the gamma log is similar throughout Unit L1. Furthermore, this logging unit correlates with Lithostratigraphic Unit I (0–135 m CSF-A) (see Lithostratigraphy), including Logging Subunits L1a and L1b.

#### 11.2.1.1. Logging Subunit L1a

Depth: 0–86 m WMSF

Downhole logging in the uppermost 86 m of Hole U1562B was acquired through drill pipe. Therefore, only suppressed gamma log measurements can be used to assess the formation. Logging Subunit L1a gamma logs show an average reading of 1.56 ± 0.7 American Petroleum Institute gamma radiation units (gAPI) (Figure F53).

#### 11.2.1.2. Logging Subunit L1b

Depth: 86–136 m WMSF

Below the drill pipe, Logging Subunit L1b was measured with a full suite of wireline logs except $V_p$, which returned unreliable data for this interval (Figure F53). The gamma log increases to a mean value of 15.6 ± 2.5 gAPI and shows multiple peaks of up to ~25 gAPI. Spectral gamma log peaks are influenced by a Th signal of up to 2.8 ppm. Density increases with depth in Subunit L1b from ~1.2 to ~1.6 g/cm³. Electrical resistivity is variable in Subunit L1a, although values fluctuate little from ~0.7 Ωm. $V_s$ increases from ~235 m/s to 390 m/s with depth in Subunit L1b. MS is variable throughout Subunit L1b, ranging 15–275 SI.

### 11.2.2. Logging Unit L2

Depth: 136–350 m WMSF

Logging Unit L2 is characterized by an overall high gamma signal (average = 20.5 ± 2.8 gAPI) that displays a cyclic pattern on a meter to decimeter scale (Figure F53). Peaks in the gamma signal are largely from a Th component. This cyclic logging response is also observed in the MS, $V_s$, and porosity measurements of this logging unit. Electrical resistivity (~0.8 Ωm), density (1.6 g/cm³), and porosity (0.75) are largely invariable with depth in Unit L2. Subunits L2a and L2b are differen-
tiated from each other based on the wavelength of these logging response cycles. Unit L2 cor-
relates to Lithostratigraphic Units II and III (see Lithostratigraphy).

11.2.2.1. Logging Subunit L2a

Depth: 136–305 m WMSF

Logging Subunit L2a shows cyclic behavior in both V<sub>S</sub> and MS, the length scale of which increases
with depth from meter scale to decameter scale. MS and V<sub>S</sub> appear to show a negative correlation

<figure><img src="image_59.png" /><figcaption>**Figure F53.** Downhole logging data, Hole U1562B. in = inches.</figcaption></figure>
such that when the MS of the sediment increases, $V_S$ decreases and vice versa. $V_S$ also shows an overall increase with depth in Subunit L2a from ~280 m/s up to between 345 and 550 m/s.

### 11.2.2.2. Logging Subunit L2b

Depth: 305–350 m WMSF

Logging Subunit L2b shows the same $V_S$ and MS cyclic behavior observed in Subunit L2a, although they occur at a shorter, meter scale, and the cycles appear to diminish with depth. MS and $V_S$ continue to show a negative correlation, and $V_S$ shows an initial drop from the bottom of Subunit L2a and then an increase with depth in Subunit L2b from ~300 to ~500 m/s.

### 11.2.3. Logging Unit L3

Depth: 350–426 m WMSF

The boundary between Logging Units L2 and L3 is marked by a sharp drop in gamma radiation, and Unit L3 displays an average of 10.2 ± 1.7 gAPI (Figure F53). The gamma log shows increased peaks in this logging unit, which, like the units above it, is dominated by a Th signal, as shown by the spectral gamma log. Electrical resistivity reports the same values as Unit L2 (~0.85 Ωm) with a slight increase at the bottom of the unit as it approaches Unit L4. Density increases with depth in Unit L3 from 1.6 to 1.8 g/cm³. At ~407 m WMSF, the caliper shows a narrowing of the hole, which is also reflected in an artificial drop in density. $V_S$ increases with depth in Unit L3 from ~440 to ~650 m/s. The lowermost part of Unit L3 (420–426 m WMSF) produced reliable $V_p$ measurements that show a rapid increase downward toward the top of Unit L4, from ~2300 to 5500 m/s. MS is invariably low in Unit L3 (average = 7.9 SI) and only shows a slight increase of up to ~40 SI at the bottom of the unit. Unit L3 correlates to Lithostratigraphic Unit IV (see Lithostratigraphy).

### 11.2.4. Logging Unit L4

Depth: 426–560 m WMSF

Logging Unit L4 represents the basement sequence drilled in Hole U1562B (Figure F53). The boundary between Units L3 and L4 is defined by marked changes in resistivity, density, porosity, $V_p$, $V_S$, and MS. The gamma log shows an initial decrease to ~7 gAPI at the top of Unit L4 that gradually increases with depth to as high as ~23 gAPI. The spectral gamma log has a strong Th signal to ~515 m WMSF, below which it becomes mostly a U signal. The transition from the sediment strata to the basement basalt is obviously marked by the previously mentioned increase in electrical resistivity (from deep-resistivity values of ~0.85 to ~51 Ωm), an increase in density (from 1.7 to 2.7 g/cm³), a decrease in porosity (from ~0.6 to 0.16), a decrease in $V_S$ (from 630 to 230 m/s), an increase in $V_p$ (from 3350 to 6090 m/s), and an initial large increase in MS (from ~13 to 605 SI). All logging responses show variability throughout the basement sequence, with increases in MS correlating to increases in $V_p$, density, and resistivity and decreases in porosity and vice versa. A notable interval at 472–476 m WMSF with low resistivity (deep resistivity of ~6.5 Ωm), high porosity (~0.62), low density (~1.8 g/cm³), low $V_p$ (2400 m/s), and low MS (~30 SI) may correlate to an intermixed sediment layer recovered in the basement basalts (see Lithostratigraphy). Similar meter-scale logging signatures can be observed throughout Unit L4 (e.g., ~464 m WMSF) that may represent further sediment layers in the basement, most of which have not been recovered in the cored material.

## 11.3. Borehole imaging

The resistivity image log acquired in the sedimentary sequence in Hole U1562B shows alternating conductive and resistive layering (Figure F54), and a mottling pattern is particularly apparent from 300 to 430 m WMSF (Subunit L2b and Unit L3). Unit L2 displays some apparently cyclic behavior in the resistivity logs; however, the frequent ledges and borehole breakouts of the hole make it difficult to interpret the signal clearly. Both the acoustic and resistivity image logs are of excellent quality in the basement sequence in Hole U1562B (>430 m WMSF) (Figure F54). Both image logs show a mostly featureless basement with some fractured to very fractured intervals that are provisionally interpreted to be small pillow lava structures. An interval of sediment is observable on
image logs at ~472–475 m WMSF (Figure F55). At some depths, wide fractures can be observed, marked by low acoustic and low resistivity values in the images (e.g., ~516 m WMSF; Figure F54).

**11.4. Downhole temperature and thermal conductivity**

During coring in Hole U1562A, downhole temperature measurements were taken with the APCT-3 tool in Unit L1. The APCT-3 tool provided equilibration temperatures ranging from 4.27°C at 30.5 m CSF-A to 7.34°C at 116 m CSF-A (Figure F56; Table T16). These observations indicate a

<figure><img src="image_60.png" /><figcaption>**Figure F54.** Wireline image data, Hole U1562B. in = inches.</figcaption></figure>
thermal gradient in the upper sediment section of 36°C/km (Figure F57A). Thermal conductivity under in situ conditions (K) was estimated from laboratory-determined thermal conductivity from Hole U1562A using the method of Hyndman et al. (1974); it varies slightly, but mostly has values around 0.8 to 0.9 W/m·K (Figure F57B). A linear function for depth-dependent thermal resistance (R) was obtained by integrating the inverse of the thermal conductivity over depth and applying a linear least-squares fit (Figure F57C). This function was used to estimate thermal resistance at each corresponding APCT-3 downhole temperature measurement depth. A heat flow of 33.5 mW/m² was obtained from a linear least-squares fit of the relationship between temperature and thermal resistance (Bullard, 1939), whose slope is the vertical heat flow (Figure F57D).

<figure><img src="image_61.png" /><figcaption>**Figure F55.** Basalt basement image features, Hole U1562B.</figcaption></figure>

<figure><img src="image_62.png" /><figcaption>**Figure F56.** APCT-3 temperature-time series and projected formation temperatures, Hole U1562A. Colored lines = observed temperature-time series, dashed lines = modeled heat pulse decay function (Hartmann and Villinger, 2002), colored dots = formation temperatures projected using best-fitting heat pulse decay function. Time is normalized with respect to onset of heat pulse decay model.</figcaption></figure>
<figure><img src="image_63.png" /></figure>

**Figure F57.** Thermal gradient and heat flow estimates, Hole U1562A. A. Projected APCT-3 formation temperature (open circles). Gray line = linear least-squares fit, *T(z)* = thermal gradient. B. Observed thermal conductivity. C. Calculated thermal resistance (*R*) (black dots). Gray line = linear least-squares fit for resistance as a function of depth, *R(z)*. D. Temperature as a function of thermal resistance (black dots) (i.e., Bullard plot). Gray line = linear least-squares fit, the gradient of which is vertical heat flow (*q*).

**12. Age model**

Site U1562, located near the eastern edge of Björn drift, has a thinner sedimentary succession than Site U1554, which is located near the center of the drift as imaged on Seismic Profile JC50-1 (see **Background and objectives**). Seismic Profile JC50-1 indicates that the upper part of the succession at Site U1562, from the seafloor reflection at ~2.7 s TWT to an angular discordance at ~2.9 s TWT, corresponds to a package of sediment that can be traced along the profile to Site U1554. Cores recovered from Site U1554 showed that this part of the succession had rapid sedimentary accumulation rates (up to ~17 cm/ky) and sedimentary facies consistent with a contourite deposit (see **Age model** in the Site U1554 chapter [Parnell-Turner et al., 2025b]). This package of sediment, which we attribute to the Björn drift depositional system, thins out eastward along the seismic reflection profile in the direction of Site U1562, but the thinning is not uniform, and a substantial stratigraphic interval within it appears to be pinched out at Site U1562 around ~2.75 s TWT. In contrast to the upper part of the succession at Site U1562, below ~2.9 s TWT the succession appears substantially thicker than the stratigraphically equivalent strata at Site U1554. From ~2.9 to ~3.05 s TWT, the seismic profile shows a series of relatively continuous parallel reflections, but below that level the reflections are less coherent to ~3.15 s TWT and then more coherent again down to the prominent basement reflection at ~3.25 s TWT.

Magnetostratigraphic (see **Paleomagnetism**) and biostratigraphic (see **Micropaleontology**) age constraints for the sedimentary succession in Holes 395C-U1562A and 395-U1562C are combined as an age-depth plot in Figure F58. The selected age model tie points are listed in Table T17. The succession appears relatively continuous to ~22 m CSF-A with a sedimentation rate of ~1.8 cm/ky. From ~22 m CSF-A to the base of Subchron C1r.3r at 28.83 m CSF-A, the succession is evidently
<figure><img src="image_64.png" /><figcaption>**Figure F58.** Age model, Hole U1562A. Additional biostratigraphic constraints from Hole U1562C are shown.</figcaption></figure>

<table><caption>**Table T17.** Age model tie points, Hole U1562A. X = coiling reversal, d-s = dextral to sinistral. Download table in CSV format.</caption><thead><tr><th>Tie point</th><th>Event (base)</th><th>Age (Ma)</th><th>Depth CSF-A (m)</th></tr></thead><tbody><tr><td>1</td><td>Top of hole</td><td>0.000</td><td>0.00</td></tr><tr><td>2</td><td>C1n (Brunhes)</td><td>0.773</td><td>13.43</td></tr><tr><td>3</td><td>C1r.1n (Jaramillo)</td><td>1.070</td><td>20.58</td></tr><tr><td>4</td><td>Top condensed interval (extrapolated down)</td><td>1.13</td><td>22.00</td></tr><tr><td>5</td><td>Bottom condensed interval (extrapolated up)</td><td>1.78</td><td>28.83</td></tr><tr><td>6</td><td>C1r.3r</td><td>1.775</td><td>28.83</td></tr><tr><td>7</td><td>C2n (Olduvai)</td><td>1.934</td><td>34.73</td></tr><tr><td>8</td><td>C2r.1n (Feni)</td><td>2.140</td><td>48.73</td></tr><tr><td></td><td>Base Pleistocene</td><td>2.59</td><td>107.50</td></tr><tr><td>9</td><td>C2r.2r (Matuyama)</td><td>2.595</td><td>108.15</td></tr><tr><td>10</td><td>Lithostratigraphic Unit I (hiatus?) (extrapolated down)</td><td>2.80</td><td>135.00</td></tr><tr><td>11</td><td>Lithostratigraphic Unit I (hiatus?) (extrapolated up)</td><td>3.50</td><td>135.00</td></tr><tr><td>12</td><td>C2An.3n (Base upper Pliocene)</td><td>3.596</td><td>137.71</td></tr><tr><td>13</td><td>C2Ar</td><td>4.187</td><td>153.73</td></tr><tr><td>14</td><td>C3r.4n (Thvera)</td><td>5.235</td><td>176.44</td></tr><tr><td></td><td>Base Pliocene</td><td>5.33</td><td>180.19</td></tr><tr><td>15</td><td>C3r (Gilbert)</td><td>6.023</td><td>207.58</td></tr><tr><td>16</td><td>C3An.2n</td><td>6.727</td><td>228.40</td></tr><tr><td></td><td>Lithostratigraphic Unit II</td><td>7.27</td><td>253.10</td></tr><tr><td></td><td>X d-s Neogloboquadrina atlantica</td><td>9.23</td><td>342.61</td></tr><tr><td></td><td>Lithostratigraphic Unit III</td><td>9.61</td><td>351.36</td></tr><tr><td>17</td><td>Top P. mayeri</td><td>10.54</td><td>372.58</td></tr><tr><td></td><td>Base upper Miocene</td><td>11.65</td><td>397.97</td></tr><tr><td>18</td><td>Lithostratigraphic Unit IV</td><td>12.95</td><td>427.73</td></tr></tbody></table>
condensed and/or subject to hiatuses. Subchron C1r.2n (Cobb Mountain; 1.180–1.215 Ma) appears to be missing despite good recovery (see **Paleomagnetism**). The interval may correspond to the pinching out of seismic reflections at ~2.75 s TWT discussed above. Below 28.83 m CSF-A, there is a marked change in the character of the MS record from higher to lower frequency cyclic- ity downcore (see **Stratigraphic correlation**). The succession from this depth to the base of Litho- stratigraphic Unit I at 135 m CSF-A contains a sequence of magnetic reversals in Chron 2 (Matuyama), providing constraints for a relatively rapid sedimentation rate of ~10 cm/ky.

The succession around the top of Lithostratigraphic Unit II at 135 m CSF-A is interpreted as a likely hiatus or series of closely spaced hiatuses that cut out or truncate a series of paleomagnetic reversals in the late Pliocene. It probably corresponds to the angular discordance in the seismic reflection profile at ~2.9 s TWT noted above. Below that level in Unit II, the biostratigraphic datums suggest a simple age-depth relationship that can be refined by the magnetostatigraphy to the base of Subchron C3An.2n (6.727 Ma) at 228.40 m CSF-A. The upper part of Unit II to the base of the Thvera Subchron C3r.4n (5.235 Ma) has an average sedimentation rate of ~2.4 cm/ky. The lower part of Unit II, from the base of Subchron C3r.4n to the base of Subchron C3An.2n, has a higher average sedimentation rate of ~3.5 cm/ky.

Lithostratigraphic Unit III (253.10 to 351.36 m CSF-A) is characterized by multiple intervals of severe soft-sediment deformation that likely indicate successive episodes of mass sediment trans- port (see **Lithostratigraphy**). This unit likely corresponds to the relatively incoherent part of the seismic reflection profile between ~3.05 and ~3.15 s TWT discussed above. Although the sedi- mentary succession registers a series of magnetic polarity reversals throughout the lower part of Unit III and Unit IV, the paleomagnetic interpretation relative to the GPTS is uncertain because of sedimentary complications and poor core recovery in Cores 395C-U1562A-58X through 64X (see **Paleomagnetism**).

The age model for the lower part of the succession in Hole U1562A is based on a series of foramin- ifer, bolboform, and nannofossil biohorizons. These constraints are considered to have low reli- ability for various reasons related to taxonomic uncertainty, low or variable abundances, and/or age calibration issues (see **Micropaleontology**). Taken together, however, they suggest a down- ward age progression with an average sedimentation rate of ~2.3 cm/ky. Lithostratigraphic Unit IV, from 351.36 m CSF-A to the basement at 427.73 m CSF-A, is characterized by sedimentary cyclicity of a fairly consistent character and wavelength as manifested in color reflectance and MS records (see **Physical properties** and **Downhole measurements**). Linear extrapolation of the age model trend to the base of Unit IV suggests an approximate age of 13.0 Ma for the oldest part of the regular sedimentary succession at the site. The age of the basement is estimated at 13.86 Ma from regional magnetic surveys (see **Background and objectives**).

A ~65 cm interval of laminated and bioturbated mudstone was found ~45 m below the top of the igneous succession in Section 395C-U1562B-14R-2 (see **Lithostratigraphy**). This interval corre- sponds to a highly distinctive ~3 m thick interval observed in the downhole resistivity and density image logs at 472.5–475.5 m WMSF (see **Downhole measurements**). The lithology is similar to Lithostratigraphic Unit IV at the base of the regular sedimentary succession but contains different assemblages of nannofossils, foraminifers, and bolboforms. The age difference from the sediment at the bottom of the regular sedimentary succession is currently difficult to constrain (see **Micro- paleontology**), but the distinctive microfossil assemblage and apparently baked nature of the sed- iment suggest it is unlikely to have infiltrated from above, and therefore probably accumulated on the seafloor before being buried by lava flows. If the ~3 m of sediment accumulated at the same rate as Unit IV, it would imply ~130 ky of deposition.

## References

* Aksu, A.E., and Kaminski, M.A., 1989. Neogene and Quaternary planktonic foraminifer biostratigraphy and biochro- nology in Baffin Bay and the Labrador Sea. In Srivastava, S.P., Arthur, M., Clement, B., et al., Proceedings of the Ocean Drilling Program, Scientific Results. 105: College Station, TX (Ocean Drilling Program), 287–304. https://doi.org/10.2973/odp.proc.sr.105.122.1989
Bullard, E.C., 1939. Heat flow in South Africa. Proceedings of the Royal Society of London, A: Mathematical and Physical Sciences, 173(955):474–502. https://doi.org/10.1098/rspa.1939.0159

Butterworth, S., 1930. On the theory of filter amplifiers. Experimental Wireless and the Wireless Engineer, 7:536–541. https://www.gonascent.com/papers/butter.pdf

Chaisson, W.P., and Pearson, P.N., 1997. Planktonic foraminifer biostratigraphy at Site 925: middle Miocene-Pleistocene. In Shackleton, N.J., Curry, W.B., Richter, C., and Bralower, T.J. (Eds.), Proceedings of the Ocean Drilling Program, Scientific Results. 154: College Station, TX (Ocean Drilling Program), 3–31. https://doi.org/10.2973/odp.proc.sr.154.104.1997

Foresi, L.M., Iaccarino, S.M., and Salvatorini, G., 2002. Neogloboquadrina alantica preatlantica, new subspecies from late Middle Miocene. Rivista Italiana Di Paleontologia E Stratigrafia, 108(2). https://doi.org/10.13130/2039-4942/5479

Hartmann, A., and Villinger, H., 2002. Inversion of marine heat flow measurements by expansion of the temperature decay function. Geophysical Journal International, 148(3):628–636. https://doi.org/10.1046/j.1365-246X.2002.01600.x

Hyndman, R.D., Erickson, A.J., and Von Herzen, R.P., 1974. Geothermal measurements on DSDP Leg 26. In Davies, T.A., Luyendyk, B.P., et al., Initial Reports of the Deep Sea Drilling Project. 26: Washington, DC (US Government Printing Office), 451–463. https://doi.org/10.2973/dsdp.proc.26.113.1974

Jones, S.M., Murton, B.J., Fitton, J.G., White, N.J., Maclennan, J., and Walters, R.L., 2014. A joint geochemical–geophysical record of time-dependent mantle convection south of Iceland. Earth and Planetary Science Letters, 386:86–97. https://doi.org/10.1016/j.epsl.2013.09.029

Kirschvink, J.L., 1980. The least-squares line and plane and the analysis of palaeomagnetic data. Geophysical Journal International, 62(3):699–718. https://doi.org/10.1111/j.1365-246X.1980.tb02601.x

Lurcock, P.C., and Florindo, F., 2019. New developments in the PuffinPlot paleomagnetic data analysis program. Geochemistry, Geophysics, Geosystems, 20(11):5578–5587. https://doi.org/10.1029/2019GC008537

Lyons, R.G., 2011. Understanding Digital Signal Processing (Third edition): Upper Saddle River, NJ (Prentice Hall). https://www.iro.umontreal.ca/~mignotte/IFT3205/Documents/UnderstandingDigitalSignalProcessing.pdf

Murton, B.J., Taylor, R.N., and Thirlwall, M.F., 2002. Plume–ridge Interaction: a geochemical perspective from the Reykjanes Ridge. Journal of Petrology, 43(11):1987–2012. https://doi.org/10.1093/petrology/43.11.1987

Ogg, J.G., 2020. Geomagnetic Polarity Time Scale. In Gradstein, F.M., Ogg, J.G., Schmitz, M., and Ogg, G. (Eds.), Geo-logic Time Scale 2020. Amsterdam (Elsevier), 159–192. https://doi.org/10.1016/B978-0-12-824360-2.00005-X

Parnell-Turner, R., White, N., Henstock, T.J., Jones, S.M., Maclennan, J., and Murton, B.J., 2017. Causes and consequences of diachronous v-shaped ridges in the North Atlantic Ocean. Journal of Geophysical Research: Solid Earth, 122(11):8675–8708. https://doi.org/10.1002/2017JB014225

Parnell-Turner, R.E., Briais, A., LeVay, L.J., Cui, Y., Di Chiara, A., Dodd, J.P., Dunkley Jones, T., Dwyer, D., Eason, D.E., Friedman, S.A., Hemming, S.R., Hochmuth, K., Ibrahim, H., Jasper, C., Karatsolis, B.T., Lee, S., LeBlanc, D.E., Lindsay, M.R., McNamara, D.D., Modestou, S.E., Murton, B., OConnell, S., Pasquet, G.T., Pearson, P.N., Qian, S.P., Rosenthal, Y., Satolli, S., Sinnesael, M., Suzuki, T., Thulasi Doss, T., White, N.J., Wu, T., and Yang Yang, A., 2025a. Expedition 395 methods. In Parnell-Turner, R.E., Briais, A., LeVay, L.J., and the Expedition 395 Scientists, Reykjanes Mantle Convection and Climate. Proceedings of the International Ocean Discovery Program, 395: College Station, TX (International Ocean Discovery Program). https://doi.org/10.14379/iodp.proc.395.102.2025

Parnell-Turner, R.E., Briais, A., LeVay, L.J., Cui, Y., Di Chiara, A., Dodd, J.P., Dunkley Jones, T., Dwyer, D., Eason, D.E., Friedman, S.A., Hemming, S.R., Hochmuth, K., Ibrahim, H., Jasper, C., Karatsolis, B.T., Lee, S., LeBlanc, D.E., Lindsay, M.R., McNamara, D.D., Modestou, S.E., Murton, B., OConnell, S., Pasquet, G.T., Pearson, P.N., Qian, S.P., Rosenthal, Y., Satolli, S., Sinnesael, M., Suzuki, T., Thulasi Doss, T., White, N.J., Wu, T., Yang Yang, A., dos Santos Rocha, V., Pearman, C., and Tian, C.Y., 2025b. Site U1554. In Parnell-Turner, R.E., Briais, A., LeVay, L.J., and the Expedition 395 Scientists, Reykjanes Mantle Convection and Climate. Proceedings of the International Ocean Discovery Program, 395: College Station, TX (International Ocean Discovery Program). https://doi.org/10.14379/iodp.proc.395.103.2025

Parnell-Turner, R.E., Briais, A., LeVay, L.J., and the Expedition 395 Scientists, 2025c. Supplementary material, https://doi.org/10.14379/iodp.proc.395supp.2025. In Parnell-Turner, R.E., Briais, A., LeVay, L.J., and the Expedition 395 Scientists, Reykjanes Mantle Convection and Climate. Proceedings of the International Ocean Discovery Program, 395: College Station, TX (International Ocean Discovery Program).

Poore, R.Z., 1979. Oligocene through Quaternary planktonic foraminiferal biostratigraphy of the North Atlantic: DSDP Leg 49. In Luyendyk, B.P., Cann, J.R., et al., Initial Reports of the Deep Sea Drilling Project. 49: Washington, DC (US Government Printing Office), 447–517. https://doi.org/10.2973/dsdp.proc.49.115.1979

Poore, R.Z., and Berggren, W.A., 1975. Late Cenozoic planktonic foraminiferal biostratigraphy and paleoclimatology of Hatton-Rockall Basin; DSDP Site 116. Journal of Foraminiferal Research, 5(4):270–293. https://doi.org/10.2113/gsjfr.5.4.270

Raffi, I., Wade, B.S., Pälike, H., Beu, A.G., Cooper, R., Crundwell, M.P., Krijgsman, W., Moore, T., Raine, I., Sardella, R., and Vernyhorova, Y.V., 2020. The Neogene Period. In Gradstein, F.M., Ogg, J.G., Schmitz, M.D., and Ogg, G. (Eds.), Geologic Time Scale 2020. (Elsevier), 1141–1215. https://doi.org/10.1016/B978-0-12-824360-2.00029-2

Siccha, M., and Kucera, M., 2017. ForCenS, a curated database of planktonic foraminifera census counts in marine surface sediment samples. Scientific Data, 4(1):170109. https://doi.org/10.1038/sdata.2017.109

Skilling, I.P., White, J.D.L., and McPhie, J., 2002. Peperite: a review of magma–sediment mingling. Journal of Volcanology and Geothermal Research, 114(1–2):1–17. https://doi.org/10.1016/S0377-0273(01)00278-5

Spiegler, D., 1999. Bolboforma biostratigraphy from the Hatton-Rockall Basin (North Atlantic). In Raymo, M.E., Jansen, E., Blum, P., and Herbert, T.D., Proceedings of the Ocean Drilling Program, Scientific Results, 162. College Station, TX (Ocean Drilling Program), 35–49. https://doi.org/10.2973/odp.proc.sr.162.013.1999
Zijderveld, J.D.A., 1967. AC demagnetization of rocks: analysis of results. In Runcorn, S.K.C., Creer, K.M., and Collinson, D.W. (Eds.), Methods in Palaeomagnetism. Developments in Solid Earth Geophysics, 3: 254–286.

https://doi.org/10.1016/B978-1-4832-2894-5.50049-5