# Integrated stratigraphy of ODP Site 1115 (Solomon Sea, southwestern equatorial Pacific) over the past 3.2 Ma

Chih-Kai Chuang, Li Lo, Christian Zeeden, Yu-Min Chou, Kuo-Yen Wei, Chuan-Chou Shen, Horng-Sheng Mii, Yuan-Pin Chang, Ying-Hung Tung

► To cite this version:

Chih-Kai Chuang, Li Lo, Christian Zeeden, Yu-Min Chou, Kuo-Yen Wei, et al.. Integrated stratigraphy of ODP Site 1115 (Solomon Sea, southwestern equatorial Pacific) over the past 3.2 Ma. Marine Micropaleontology, 2018, 144, pp.25-37. 10.1016/j.marmicro.2018.09.003. hal-02308802

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# Integrated stratigraphy of ODP Site 1115 (Solomon Sea, southwestern equatorial Pacific) over the past 3.2 Ma

Chih-Kai Chuang<sup>a,#</sup>, Li Lo<sup>a,b,#,*</sup>, Christian Zeeden<sup>c</sup>, Yu-Min Chou<sup>d</sup>, Kuo-Yen Wei<sup>a</sup>,
Chuan-Chou Shen<sup>a,e</sup>, Horng-Sheng Mii<sup>f</sup>, Yuan-Pin Chang<sup>g</sup>, Ying-Hung Tung<sup>a</sup>

a. High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Department of Geosciences, National Taiwan University, Taipei 10617, TAIWAN ROC

b. Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PRC

c. IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ Paris 06, Univ Lille, 75014 Paris, FRANCE

d. Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen, Gongdong 518055, PRC

e. Research Center for Future Earth, National Taiwan University, Taipei 10617, TAIWAN ROC

f. Department of Earth Sciences, National Taiwan Normal University, Taipei 10677, TAIWAN ROC

g. Department of Oceanography, National Sun Yat-sen University, Kaohsiung, 80424, TAIWAN ROC

23 \# These authors contributed equally to this work

24

25 \* Corresponding author:

26 Li Lo: lilo@gig.ac.cn

27

28 Revised and resubmitted to Marine Micropaleontology

29

30 September 16, 2018

31
33 We provide an integrated stratigraphy for the southern margin of the
34 Indo-Pacific Warm Pool back to 3.2 million years ago (Ma) from ODP Site 1115,
35 Hole B (9°11'S, 151°34'E, water depth 1149 m, 0-217 meters below sea floor), the
36 only hole with core recovery beyond 4.4 m. An initial age model based on 14
37 calcareous nannofossil datums, 5 planktonic foraminiferal biostratigraphic events and
38 12 magnetic polarity reversals is refined by planktonic foraminiferal *Globigerinoides
39 sacculifer* (300-355 µm) δ¹⁸O stratigraphy. The planktonic δ¹⁸O record with an
40 average 3-4 kyr resolution matches the global stack LR04 (Lisiecki and Raymo,
41 2005). The 41-kyr obliquity and 100-kyr eccentricity patterns show good correlation
42 between the LR04 and the dataset presented herein. The precession amplitude
43 matches eccentricity, supporting the established stratigraphy. Sedimentation rates at
44 Hole 1115B have decreased from 9.3 to 4.5 cm/kyr during the past 3.2 Ma towards
45 present, mainly due to the gradual deepening of the Woodlark Basin. The planktonic
46 δ¹⁸O record from Site 1115 matches the global climate evolution well.

47

48 **Keywords:** Indo-Pacific Warm Pool; integrated stratigraphy;

49
## 1. Introduction

The Indo-Pacific Warm Pool (IPWP) is the most important global moisture and latent heat source due to its high sea surface temperature (SST, annual mean SST >28 °C) (Cane, 1998). Interannual to decadal oscillations, e.g., El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) govern regional to large-scale precipitation patterns and ocean heat exchange (Giannini et al., 2000; Newman et al., 2016). On millennial time scales and events, such as the Younger Dryas and Heinrich events, the IPWP acts as an amplifier to transport cross-equatorial energy flow by the interhemispheric temperature gradients and transmits climatic perturbations from the Northern to the Southern Hemisphere (Lo et al., 2014; McGee et al., 2014). On longer timescales, previous studies used the planktonic foraminiferal Mg/Ca ratio-derived sea surface temperature records to define the zonal and meridional temperature gradient evolution over the past 5 Ma (Wara et al., 2005; Ford et al., 2015). High latitude cooling during the Plio-Pleistocene epochs (Liu et al., 2004; Martinez-Garcia et al., 2010) may have driven these trends. However, most available records are of insufficient temporal resolution (<5-kyr) to determine the timing of events on orbital time scales, especially when older than 2 Ma. To better assess the temporal variability and relation to orbital climate forcing, we used ODP Site 1115, Hole B in the southwestern equatorial Pacific Ocean to develop an integrated
69 stratigraphy using planktonic foraminiferal $\delta^{18}$O and bio-magnetostratigraphy with
70 radiometric dating support.

71

72 Sediments obtained at ODP Hole 1115B provide a continuous record back to
73 3.2 Ma with an average sedimentation rate of ~7 cm/kyr and good carbonate
74 preservation (Takahashi et al., 2001). Here we established a new age model of ODP
75 Hole 1115B based upon a total of 14 calcareous nannofossil events, 5 planktonic
76 foraminiferal datum levels and 12 magnetic reversals with a correlation of the
77 *Globigerinoides sacculifer* $\delta^{18}$O record to a global LR04 stack (Liseciki and Raymo,
78 2005). We propose this as a new reference stratigraphy for the equatorial Pacific i.e.,
79 for addressing regional responses during global major climatic events such as the
80 Middle Pleistocene Transition (Raymo et al., 2006; Elderfield et al., 2012), Northern
81 Hemisphere glaciations (Haug et al., 1998; Bartoli et al., 2005), and the Middle
82 Pliocene warm period (Dowsett et al., 1996; Haywood et al., 2016). We use an
83 integrated stratigraphic approach (e.g., Hilgen et al. 2014), and combine information
84 from biostratigraphy, magnetostratigraphy, tephra and a planktonic $\delta^{18}$O record
85 matched to an established reference dataset (LR04; Lisiecki and Raymo, 2005).

86

87 **2. Material and methods**
88 2.1 ODP Hole 1115B

Our study is based on one hole from ODP Site 1115, since Hole 1115B is the only hole with core recovery below 4.4 m (Shipboard Scientific Party, 1999). ODP Site 1115 is located in the Solomon Sea, southwestern Pacific Ocean (9°11′S, 151°34′E, 1149 m depth, Fig. 1) (Goodliffe et al., 2001; Takahashi et al., 2001). Total sediment column length of this core is 293.1 m, and the sediment recovery rate is >97% (286.84 m in total). The major sediments are composed of greenish-gray nannofossil-rich silty clay and calcareous sand (Taylor et al., 1999; 2002). The calcium carbonate content is >60% from 0–100 meters below sea floor (mbsf), and the lower sections at an interval of 100–300 mbsf are less diluted by terrigenous sediment (up to ~20%; Taylor et al., 1999; 2002). A geochemical study suggests that the major source of terrigenous sediment is tropically weathered basic igneous rocks, which are most likely from the Papuan ophiolite (Robertson and Sharp, 2002). Four high-K volcanic ash layers and mud-rich tephra layers are observed (Table 2). The existence of these tephra layers indicates explosive eruptions in the nearby region (Robertson and Sharp, 2002). There are no reported turbidite layers of hiatuses in the studied sections (0–217 mbsf), corresponding to the last 3.2 Ma (Takahashi et al., 2001). Material from the upper 23 core segments of ODP Hole 1115B was used in this study.
107

108 2.2 Sediment depth calibration

109 Sediment expansion requires an adjustment to the depth scale of ODP Hole
110 1115B. Therefore, we converted the reported depth in mbsf (Taylor et al., 1999; 2002)
111 to a continuous depth scale (depth*) by adding the recovered and expanded sediment
112 from all cores (Supplementary Table 1). We assumed the expanded sediments in each
113 section to be the original sediment column, and then added the depth from cores 1 to
114 23. No gaps were observed during the drilling process according to the composite
115 depth calibration between ODP Holes 1115B and 1115C, and geophysical studies
116 presented in the initial reports (Taylor et al., 1999; 2002; Goodliffe et al., 2001). The
117 accumulated difference from the uncorrected sediment column for the study section
118 (0–217 mbsf) is ~9 m, consistent with an average expansion rate of 4–5% (Taylor et
119 al., 1999; 2002). Note that in the following sections, depth* is used.

120

121 2.3 Planktonic foraminiferal $\delta^{18}$O stratigraphy

122 Shells of the planktonic foraminifera *Globigerinoides sacculifer* (300–355 µm)
123 were picked at 30-cm intervals and analyzed to construct an oxygen isotope
124 stratigraphy. Five-to-six *G. sacculifer* shells were cleaned as follows: shells were
125 immersed in methanol and ultrasonicated for a few seconds to remove clay. Sodium
hypochlorite (NaOCl) was added for 48 hours to remove organic matter. Deionized

(DI) water was used to rinse the shells between steps. Cleaned foraminifera shells

were dried at 50°C in an oven for 48 hours. Oxygen isotope analysis was conducted

on a Micromass IsoPrime mass spectrometer equipped with the Multicarb automatic

system at the Department of Earth Sciences, National Taiwan Normal University.

Isotopic data (Supplementary Table 1) are reported relative to the Vienna Peegee

belemnite (VPDB) standard through the calibration of NBS-19 (National Bureau of

Standards, δ¹⁸O = -2.20‰). Reproducibility with replicate analyses of NBS-19 were

±0.05‰ for δ¹⁸O (1σ, n = 261; Lo et al., 2013).

Based on an age model from the integrated stratigraphy (see sections 2.4-2.6), we

correlated planktonic foraminiferal δ¹⁸O to a global benthic foraminiferal stack (LR04;

Lisiecki and Raymo, 2005) to determine age. The LR04 stack represents a composite

record of global benthic foraminiferal δ¹⁸O records. Its time scale is based on a global

ice volume model, the Imbrie and Imbrie (1980) ice model. Although planktonic

foraminiferal δ¹⁸O comprises signals of both global ice volume and surface

hydrological variations, previous studies in the Solomon Sea show no clear phase

differences (< 1–2 kyr) between planktonic and benthic foraminiferal δ¹⁸O
144 stratigraphy (Liu et al., 2015; Lo et al., 2017). We adopted a direct correlation
145 approach in this study.

146

147 2.4 AMS <sup>14</sup>C and <sup>40</sup>Ar-<sup>39</sup>Ar dates

148 Tests of the planktonic foraminifera *G. sacculifer* (>500 µm) at depths of 0.11,
149 0.21, 0.31, 0.41, and 0.51 m, were picked for accelerator mass spectrometry (AMS)
150 <sup>14</sup>C dating conducted by the Rafter Laboratory, New Zealand. <sup>14</sup>C ages were
151 calibrated to calendar age with CALIB 7.1 using the MARINE 13 calibration curve.
152 No reservoir age was assumed (Table 1, Reimer et al., 2013; Stuiver et al., 2017).
153 <sup>40</sup>Ar-<sup>39</sup>Ar dating results of tephra (Lackschewitz et al., 2001; Takahashi et al., 2001)
154 were converted to depth* scale shown in Table 2 and Figure 2.

155

156 2.5 Paleomagnetic investigations and time scale

157 Shipboard paleomagnetic data (Ishikawa et al., 2001) indicate that the natural
158 remnant magnetization (NRM) of samples from ODP Hole 1115B contain two
159 paleomagnetic components. The soft component could be removed by alternating
160 field (AF) demagnetization of (up to) 10 milli (10<sup>-3</sup>) Tesla (mT). The AF
161 demagnetization curve of most samples showed one principal component, which
162 decayed stably toward the origin after 15–25 mT and is considered to be the
163 characteristic remnant magnetization (ChRM). In this study, we used the
164 paleomagnetic data after a 20 mT AF demagnetization as the ChRM and to identify
165 the depth of geomagnetic reversal boundaries in ODP Hole 1115B.

166

167 2.6 *Biostratigraphy*

168 2.6.1 *Calcareous nannofossils, counting and identification*

169 Sieved sediment samples (<63 µm) were used to make smear slides for
calcareous nannofossil counting. We recorded the relative abundance using a
170 semi-quantitative analysis under a Zeiss Axioskop polarizing microscope. Shipboard
171 datums were used to identify the key species (Taylor et al., 2002). These species were
172 counted in 100 fields of view, and the total count of nannofossils was larger than 500
173 individuals (Table 4). Taxonomy of nannofossils is based on Perch-Nielsen (1985)
174 and Bown and Young (1998). We identified the biostratigraphic event as the
175 mid-point in the abundance slope of the first and/or last occurrence (FO/LO) event
176 investigated according to the studies using sediment mixing model (Löwemark et al.,
177 2008). They show that the effect from bioturbation is neglectable during the mid-point
178 of the abundance changes. All events are reported in both mbsf and depth* for further
179 examination (Fig. 4a-n).

181
182 For the examinations of FO and LO events of medium *Gephyrocapsa* spp., all
*Gephyrocapsa* specimens, including the small *Gephyrocapsa* spp., were counted.

183 Regarding the FO and LO events of the large *Gephyrocapsa* spp., only the number of
medium and large size *Gephyrocapsa* spp. were counted and their ratios were
calculated with the following equations (Raffi, 2002):

187 Medium *Gephyrocapsa* ratio =

188 [Medium *Gephyrocapsa* spp. / (Medium + Small *Gephyrocapsa* spp.)] x 100%

189

190 Large *Gephyrocapsa* ratio =

191 [Large *Gephyrocapsa* spp. / (Large + Medium *Gephyrocapsa* spp.)] x 100%

192

193 2.6.2 Planktonic foraminiferal events

194 Tests for examining planktonic foraminiferal biostratigraphic events were picked
195 from the >250 µm size fraction. For *Globigerinoides ruber* (pink), *Globigerinoides
196 fistulosus*, and *Dentoglobigerina altispira*, all foraminiferal tests were counted and
197 then normalized by dry sediment weight (Fig. 4o, 4p, 4r). For the left coiling event 5
198 (L5, Saito, 1976) of *Pulleniatina* spp., all *Pulleniatina* spp. tests were counted (Fig.
199 4q). The right coiling relative proportion (RC%) was calculated with the following
200 equation:
201 RC% = [Right coiling / (Right coiling + Left coiling)] x 100%.

202

203 2.7 *Time series analysis*

204 Filtering of the planktonic δ¹⁸O data from ODP Hole 1115B was performed to
205 improve the understanding of its relation to the LR04 stack, and to investigate specific
206 frequency ranges related to orbital climate forcing. Filtering was done using a Taner
207 (Taner, 1992) filter with the R 'astrochron' package (Meyers, 2014; Fig. 5).

208 Frequency (1/kyr) ranges of 0.054–0.041, 0.027–0.023, and 0.0125–0.0077 were used
209 for extracting and comparing precession, obliquity and eccentricity components from
210 the time series. Roll-off rates of 10⁵, 10³, and 10¹⁰ were used, respectively.

211

212 The integrated and correlative time scale was tested by comparing the precession
213 amplitude of data to the precession from the orbital target using the 'testPrecession'
214 algorithm (Meyers, 2014; Zeeden et al. 2015). Results are displayed in Supplementary
215 Figure 1. For wavelet analysis, we resampled the LR04 and ODP Hole 1115B δ¹⁸O
216 with 2-kyr resolution and used the methods from Grinsted et al. (2004).

217

218 **3. Results and Discussion**

219 *3.1 Oxygen isotope stratigraphy*
220 Planktonic foraminifera G. sacculifer oxygen isotopes were measured to achieve
221 a resolution of 3–4 kyr, at depth intervals of 10–30 cm in the upper 225.46 m from
222 ODP Hole 1115B (n = 821, Fig. 2a, Supplementary Table 1). Averaged δ¹⁸O is -1.88
223 ± 0.18‰ (1σ, n = 129) for the interval of 180-225 m (~2–3.2 Ma) and -1.16 ± 0.47‰
224 (1σ, n = 185) at 0–40 m (0–1 Ma), respectively. The absolute values and the
225 amplitude of fluctuations between the glacial/interglacial (G/IG) periods are
226 significantly larger during the last million years than the rest of the record, as
227 anticipated for the post-MPT values. The δ¹⁸O values increase clearly by 0.24 and
228 0.64‰ in the intervals at 170–180 m and 40–50 m, respectively. The G/IG differences
229 in 50–170 m (1–2 Ma) are 0.4–0.6‰. There are 134 G/IG cycles, including Marine
230 Isotope Stage (MIS) 1–104, G1-G22, K1-K2, and KM1-KM6, according to the stages
231 recognized in LR04 global benthic foraminiferal δ¹⁸O stratigraphy (Figs. 2b and 5)
232 (Lisiecki and Raymo, 2005).

233

234 3.2 *Bio-magnetostratigraphy, radiometric age controls, and sedimentation rates*

235 Integrated stratigraphy constrains the oxygen isotope stratigraphy correlation:
236 ¹⁴C (Table 1) and ⁴⁰Ar-³⁹Ar (Table 2) dates, paleomagnetic reversal events (Table 3),
237 calcareous nannofossil (Table 4), and planktonic foraminiferal (Table 5) datum levels
238 (Fig. 3) were also used to refine the entire chronology. Major magnetic boundaries of
239 Brunhes/Matuyama at 0.779 Ma and Matuyama/Gauss at 2.574 Ma, and the
240 chronologies of subchrons, such as Jaramillo at 0.997–1.085 Ma, Cobb Mountain at
241 1.191–1.205 Ma, Olduvai at 1.780–1.945 Ma, Réunion at 2.122–2.142 Ma, and Kaena
242 at 3.043–3.108 Ma, were identified, all consistent with previous reports (Lisiecki and
243 Raymo, 2005; Gradstein et al., 2012).

244

245 Fourteen calcareous nannofossil and five planktonic foraminiferal
246 biostratigraphic events are identified (Fig. 4, Tables 4 and 5). These can be grouped as
247 follows: (1) Global or regional synchronous events corresponding to similar timing
248 and/or MIS periods, which include the First occurrence (FO) of *Emiliania huxleyi*
249 (MIS 8), Last occurrence (LO) of *Pseudoemiliania lacunosa* (MIS 12), LO of
250 *Reticulofenestra asanoi* (MIS 22), LO and FO of large *Gephyrocapsa* (MIS 37 and
251 54), LO of *Calcidiscus macintyrei* (MIS 54/55 boundary), LO of *Discoaster brouweri*
252 (MIS 71), and 5 planktonic foraminiferal events (Thompson et al., 1979; Lee et al.,
253 1999; Resig et al., 2001; Tian et al., 2002). (2) The events are synchronous in low
254 latitudes and/or represent western Pacific Ocean events, e.g., re-entrance of medium
255 *Gephyrocapsa* (MIS 28-29, Raffi et al., 2006) and FO of medium *Gephyrocapsa* (MIS
256 59-61) (Takayama et al., 1993; Berger et al., 1994; Lee et al., 2001; Horng et al., 2002;
257 Clemens et al., 2003; Su et al., 2004). (3) Asynchronous events include FO of
258 *Reticulofenestra asanoi* (1.105 Ma), LO of *Helicosphaera sellii* (1.278 Ma), LO of
259 *Discoaster pentaradiatus* (2.481 Ma), LO of *Discoaster surculus* (2.717 Ma), and LO
260 *Discoaster tamalis* (2.757 Ma). These five events have different regional ages as
261 reported from previous studies. For example, the age of FO of *R. asanoi* have been
262 reported as 1.136 Ma and 1.078 Ma in the equatorial Atlantic Ocean and
263 Mediterranean Sea, respectively (Raffi et al., 2006). The age of LO of *D.*
264 *pentaradiatus* varies from 2.393-2.512 Ma in the Atlantic Ocean and the
265 Mediterranean Sea (Raffi et al., 2006) and the age same event in the Solomon Sea lies
266 between this range. Overall, the ages of these five events from ODP Hole 1115B are
267 within the ranges that have been reported by previous studies (Takayama et al., 1993;
268 Wei, 1993; Berger et al., 1994; Mix et al., 1995; Chapman et al., 1997; Wang et al.,
269 2000; Lee et al., 2001; Horng et al., 2002; Raffi, 2002; Clemens et al., 2003; Su et al.,
270 2004; Raffi et al., 2006; Anthonissen and Ogg, 2012). Details of regional and between
271 sites comparisons are summarized in Table 6. The origin of these differences is
272 unclear and can unfortunately not be resolved with present data.

273

274 Biostratigraphic FO/LO events in ODP Hole 1115B show several different
275 patterns. Some show multiple steps, for example, LO of *P. lacunosa* and LO of *R.*
276 *asanoi* (Fig. 4b, 4c), and some show a major step, for example, FO of *E. huxleyi* and
277 LO of *D. surculus* (Fig. 4a, 4m). These characteristics may relate to potential
278 bioturbation, regional floral/fauna distributions, and synchronicity of different
279 biostratigraphic events. Further regional to global high-resolution records may shed
280 light on the geographic and chronologic differences of these events.

281

282 Sedimentation rates increase at ODP Hole 1115B downcore. Average
283 sedimentation rates are 4.5, 6.7, and 9.3 cm/kyr at 0–1, 1–2, and 2–3.2 Ma,
284 respectively (Fig. 3). The late Pleistocene sedimentation rate is similar to other
285 sediment cores in the Solomon Sea, as reported by Liu et al. (2015) and Lo et al.
286 (2017). The increasing sedimentation rates in early Pleistocene-Pliocene may be
287 attributed to higher silicate clastic input into the shallower basin at that time
288 (Takahashi et al., 2002).

289

290 *3.3 Comparison of the ODP Hole 1115B δ<sup>8</sup>O stratigraphy to the LR04 stack*

291 In general, the G/IG variation pattern of ODP Hole 1115B agrees well with the
292 LR04 at 0–2.2 Ma (Fig. 5a, 5b). MIS 16 is 0.2–0.4‰ heavier than MIS 12, and G/IG
293 differences are not clear between 1.1–0.9 Ma.

294
Clear G/IG variations in the interval from 2.5 to 2.4 Ma are also captured by
ODP Hole 1115B. The intensification of G/IG differences in MIS 96, 98, and 100 has
been demonstrated by eastern equatorial Pacific SST and benthic foraminiferal $\delta^{18}$O
stratigraphy worldwide (Shackleton et al., 1990; Lisiecki and Raymo, 2005). During
3.2–2.6 Ma, higher sedimentation rates with lower G/IG differences make it difficult
to correlate the ODP Hole 1115B data to the LR04. We conducted an iteration method
to correlate ODP Hole 1115B stratigraphy to the LR04 stack. First, we correlated $\delta^{18}$O
data directly to obtain the age of each magneto-biostratigraphic event, and then
applied fixed magneto-biostratigraphy ages to the previous version of the age model
for slight modification. Results from bandpass filtering and the testPrecession method
(Zeeden et al., 2015) confirm the major Milankovitch cycles, and the similarity
between ODP Hole 1115B and LR04 (Fig 5c, Supplementary Fig. 1). There is a
significant $\delta^{18}$O increase at ~2.75 Ma but there is no clear elevation at ~3.15 Ma.

### 3.4 Time scale testing and orbital imprint

Both the ODP Hole 1115B planktonic $\delta^{18}$O record and the LR04 stack were
filtered to facilitate comparisons of their precession, obliquity and eccentricity
components. The result is depicted in Figure 6. All components (precession, obliquity,
eccentricity) show similar features in our record and LR04, ensuring confidence in the
314 correlative age model and also the assumption that data are actually comparable.

315 Furthermore, the 100-kyr eccentricity filtering shows a clear intensification after ~700 ka, which corresponds to the late Pleistocene intensification G/IG variations. Note that

316 the data resolution older than ~1 Ma is on the edge of being useful for investigating precession (Martinez et al., 2016); results regarding precession and its amplitude should be treated with caution for the interval older than 1 Ma.

317

318

319

320

321 An additional significance test for precession-dominated time scales (Meyers 2014; Zeeden et al., 2015) is applied to avoid artifacts of time scale alignment

322

323 (Shackleton et al., 1995a; Huybers & Aharonson, 2010). It should be noted that

324 precession is not a dominant contributor to most of the Plio-Pleistocene δ¹⁸O variation;

325 the signals may not be as clear as those in precession-dominated records. Even given

326 this constraint, a significant (at a 95% confidence interval) correlation between

327 precession amplitude as reconstructed in the ODP Hole 1115B data and the orbital

328 template (Laskar et al., 2004) is observed, providing good confidence for the overall

329 age model. As can be seen in Supplementary Fig. 1, the fit is not perfect in all

330 intervals as can be expected since the dataset does not appear to show a lot of

331 precession. Wavelet analyses show similar results to the filtering ones, and similarity

332 between the Hole 1115B dataset and the LR04 (Fig. 7). Persistent 41-kyr cycles are
333 observed in both LR04 and ODP Hole 1115B $\delta^{18}$O stratigraphy. Eccentricity (100-kyr) cycles become dominant only after ~0.8 Ma, and precession cycles are not clear in either record. Overall, the time scale accuracy may be estimated at 10–15 kyr, including the time scale uncertainty reported by Lisiecki and Raymo (2005), and the data- and correlation-resolution from this study. Accordingly, obliquity- and eccentricity cycles should be correctly identified, and that their phase is about correct and not inverted. It also means that the precession phase of this record is uncertain and can hardly be assessed in the older part. Cyclicity is generally clearer and more significant in the LR04 stack, which is not surprising due to its stacked nature which removes noise.

343

344 3.5 Relation to global climate evolution

345 ODP Hole 1115B *G. sacculifer* $\delta^{18}$O shows its minimum during the Middle Pliocene warm period (3.3–3.0 Ma, Haywood et al., 2016). A gradual increasing (~0.4 ‰) during 3–2.5 Ma is accompanied with the Northern Hemisphere Glaciation (Haug et al., 1998). The glacial-interglacial differences of *G. sacculifer* $\delta^{18}$O show relatively small variations (0–0.4‰) for the past 3.2–1.0 Ma. During the cooling period of the Indonesian Through Flow at 2.5–1.5 Ma and the establishment of a Northwestern dust path since 2.4 Ma (Christensen et al., 2017), the Solomon Sea shows a relatively
stable condition and persistent G/IG differences of 0.2–0.4‰ in δ¹⁸O. The major shifting of G/IG δ¹⁸O (up to 0.8‰) differences happened during 0.95–0.65 Ma which is corresponding to the Middle Pleistocene Transition (Elderfield et al., 2012) and similar to previous *G. sacculifer* δ¹⁸O record from Ontong Java Plateau (Berger et al., 1994). A previous study (Lo et al., 2017) shows that large late Quaternary G/IG temperature variations at 3–4 °C in the Solomon Sea coincide with G/IG δ¹⁸O differences (Fig. 8). The similar evolution of orbital forcing in Pacific surface waters and in global deep-sea records is striking. This means that global temperature evolution was the main driver of Pacific surface planktonic foraminiferal δ¹⁸O over the last 3.2 Ma, indicating that high-latitude processes dominated also equatorial surface water properties.

363

### 4. Conclusions

We reconstructed an integrated stratigraphy in the southwestern equatorial Pacific Ocean for the past 3.2 Ma using ODP Hole 1115B. We correlated planktonic foraminiferal δ¹⁸O to the LR04 stack with consistent support of magnetic reversals, calcareous nannofossil and planktonic foraminiferal biostratigraphy, as well as radiometric dates (¹⁴C and ⁴⁰Ar/³⁹Ar). Sedimentation rates increase from 4.5 to 9.3 cm/kyr in the last 3.2 Ma, mainly due to a shallowing of the Woodlark Rise. The
371 planktonic foraminifera $\delta^{18}$O record matches the LR04 stack well, demonstrating that
372 the evolution of the surface waters in the western Pacific has been closely coupled
373 with global climate evolution, and particularly global ice-volume change. Here, an
374 integrated stratigraphy in the southern marginal Indo-Pacific Warm Pool region with a
375 reliable and high-resolution timescale is provided for further paleoceanographic
376 studies.

377

378 Acknowledgements

379 This study was supported by National Science Council Project (NSC94
380 2611-M-002-009 to KYW). The authors would like to give thanks to E.-E. Cheng,
381 H.-W. Huang, and H.-Y. Yang for their assistance in the lab. Y.-C. Chen helped
382 picking foraminifera. Part of the biostratigraphy studies were initiated by Y.-H. Lai,
383 M.-T. Chiang, and C.-Y. Chen. M.-Y. Lee, H.-C. Ke, and P.-C. Lin helped to
384 establish and tune stable isotope stratigraphy. This research used samples that were
385 provided by the Ocean Drilling Program (ODP). ODP was sponsored by the U.S.
386 National Science Foundation (NSF) and participating countries under management of
387 Joint Oceanographic Institutions (JOI), Inc.
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<figure><img src="image_2.png" /><figcaption>Fig. 1. Locations (a) and bathymetry (b) of ODP Hole 1115B (9°11′S, 151°34′E, water depth 1149 m, Taylor et al., 2002) in the Solomon Sea, southwestern Pacific Ocean. Black line represents 28°C contour of long term sea surface temperature (from 1990 to 2017), the value is calculated from NOAA_OI_SST_V2 (NOAA Physical Sciences Division, 2017) and the map is made by GMT software (Wessel et al., 2013)</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>**Fig. 2.** ODP Hole 1115B *Globigerinoides sacculifer* δ¹⁸O (red) plotted in continuous depth (depth*), compared with the LR04 stack (black, Lisiecki and Raymo, 2005). Orange crosses represent the age model tie points (Supplementary Table 1). Paleomagnetic epochs are present in black and white stripes. Abbreviations of polar reversal events are J: Jaramillo, CM: Cobb Mountain, O: Olduvai, R: Réunion, and K: Kaena.</figcaption></figure>
<figure><img src="image_4.png" /><figcaption>**Fig. 3.** ODP Hole 1115B paleomagnetic (black triangles), nannofossil (green square) and planktonic foraminiferal (purple diamond) biostratigraphic events, planktonic foraminiferal AMS $^{14}$C (yellow cross), and volcanic glass $^{40}$Ar-$^{39}$Ar dates (gray cross). Depth* and gray dashed line represent continuous depth in meter and sedimentation rates (cm/kyr), respectively. Paleomagnetic epochs in depth* and the abbreviations are the same as in Fig. 2.</figcaption></figure>
<figure><img src="image_5.png" /></figure>

<figure><img src="image_6.png" /></figure>

<figure><img src="image_7.png" /></figure>

<figure><img src="image_8.png" /></figure>

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

<figure><img src="image_10.png" /></figure>
<figure><img src="image_11.png" /></figure>

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

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

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

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

<figure><img src="image_16.png" /></figure>
<figure><img src="image_17.png" /><figcaption>**Fig. 4.** ODP Hole 1115B calcareous nannofossils (a-n, green) and planktonic foraminifera (o-r, pink) biostratigraphic events on top of planktonic foraminifera oxygen isotopic curve (red). The numbers in black and red are biostratigraphic event depth and MIS stages, respectively. All data are listed in Tables 4 and 5.</figcaption></figure>

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<figure><img src="image_18.png" /><figcaption>**Fig. 5.** Comparison of ODP Hole 1115B *G. sacculifer* δ<sup>18</sup>O (red) and the LR04 stack (black) for following time intervals: 0-1.1 Ma (**a**), 1.1-2.2 Ma (**b**), 2.2-3.2 Ma (**c**). Orange crosses and the gray line depict the age model tie points and sedimentation rate, respectively (Fig. 2 and Supplementary Table 1).</figcaption></figure>

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<figure><img src="image_19.png" /><figcaption>**Fig. 6.** Comparison of precession (**a**), obliquity (**b**), and 100-kyr eccentricity (**c**) filters of ODP Hole 1115B *G. sacculifer* δ<sup>18</sup>O (red) and the LR04 stack (black). Please note that precession and eccentricity are weak components in the time interval older than ca. 1 Ma, and that therefore filter results may not be meaningful.</figcaption></figure>

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<figure><img src="image_20.png" /><figcaption>**Fig. 7.** Wavelet analysis results of (a) ODP Hole 1115B and (b) LR04. See the overall similarity of the evolution over time, especially in the ~40 and ~100 kyr period bands related to orbital forcing.</figcaption></figure>

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<figure><img src="image_21.png" /><figcaption>Fig. 8. Glacial/interglacial differences (b; purple) of ODP Hole 1115B *G. sacculifer* δ¹⁸O (a). The red and blue curves represent 100-kyr smoothed interglacial and glacial averaged δ¹⁸O, respectively.</figcaption></figure>

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663

664 Supplementary material to the manuscript

665 Integrated stratigraphy of ODP Site 1115 (Solomon Sea, southwestern equatorial

666 Pacific) over the past 3.2 Ma

667 by Lo *et al.*, (submitted 2018)

668

669

<figure><img src="image_22.png" /></figure>

670

671 **Supplementary Fig. 1.** Results from testing the precession amplitude in data against
672 the orbital template using the testPrecession algorithm (Zeeden et al., 2015). Overall
673 correlation is highly significant, giving confidence in the overall time scale.

674

675 **Supplementary Table 1.** ODP Hole 1115B *Globigerinoides sacculifer* $\delta^{18}$O, age
676 model tie points, sedimentation rates, and meters below sea floor (mbsf) versus
677 continuous depth (depth*) data.

678
**Table 1**

<table><caption>ODP Hole 1115B planktonic foraminiferal (Globigerinoides sacculifer, >500 µm) AMS $^{14}$C dates.</caption><thead><tr><th>Core</th><th>Section</th><th>Interval (cm)</th><th>mbsf (m)</th><th>Depth* (m)</th><th><sup>14</sup>C age (yr)</th><th>error (yr, 1σ)</th><th>Calendar age (kyr)</th><th>error (kyr, 1σ)</th></tr></thead><tbody><tr><td>1H</td><td>1W</td><td>10-12</td><td>0.11</td><td>0.11</td><td>4339</td><td>40</td><td>4.46</td><td>0.05</td></tr><tr><td>1H</td><td>1W</td><td>20-22</td><td>0.21</td><td>0.21</td><td>5943</td><td>30</td><td>6.35</td><td>0.04</td></tr><tr><td>1H</td><td>1W</td><td>30-32</td><td>0.31</td><td>0.31</td><td>8032</td><td>30</td><td>8.48</td><td>0.04</td></tr><tr><td>1H</td><td>1W</td><td>40-42</td><td>0.41</td><td>0.41</td><td>10449</td><td>40</td><td>11.56</td><td>0.15</td></tr><tr><td>1H</td><td>1W</td><td>50-52</td><td>0.51</td><td>0.51</td><td>14105</td><td>65</td><td>16.51</td><td>0.14</td></tr></tbody></table>
<caption>**Table 2**</caption>

ODP Hole 1115B <sup>40</sup>Ar-<sup>39</sup>Ar dates. Depth (mbsf) are revised from Taylor et al. (2002).

<table><thead><tr><td>mbsf (m)</td><td>Depth* (m)</td><td>Age (Ma)</td><td>error (1σ, Ma)</td></tr></thead><tbody><tr><td>3.97</td><td>3.97</td><td>0.135</td><td>0.008</td></tr><tr><td>88.31</td><td>92.63</td><td>1.71</td><td>0.06</td></tr><tr><td>169.31</td><td>177.06</td><td>2.77</td><td>0.04</td></tr><tr><td>180.63</td><td>198.34</td><td>2.84</td><td>0.03</td></tr></tbody></table>
<caption>**Table 3**</caption>

Paleomagnetic stratigraphy of ODP Hole 1115B. Depth (mbsf) are revised from Taylor et al. (2002).

<table><thead><tr><th>Polar reversal event no.</th><th>Paleomagnetic event</th><th></th><th>mbsf (m)</th><th>Depth* (m)</th><th>Age (Ma)<sup>#</sup></th></tr></thead><tbody><tr><td>m1</td><td>Brunhes/Matuyama boundary</td><td></td><td>33.70</td><td>34.88</td><td>0.779</td></tr><tr><td>m2</td><td rowspan="2">Jaramillo</td><td>Top</td><td>43.35</td><td>45.00</td><td>0.997</td></tr><tr><td>m3</td><td>Bottom</td><td>47.20</td><td>49.48</td><td>1.085</td></tr><tr><td>m4</td><td rowspan="2">Cobb Mountain</td><td>Top</td><td>53.25</td><td>55.54</td><td>1.191</td></tr><tr><td>m5</td><td>Bottom</td><td>54.25</td><td>56.54</td><td>1.205</td></tr><tr><td>m6</td><td rowspan="2">Olduvai</td><td>Top</td><td>90.50</td><td>94.83</td><td>1.780</td></tr><tr><td>m7</td><td>Bottom</td><td>102.40</td><td>107.41</td><td>1.945</td></tr><tr><td>m8</td><td rowspan="2">Réunion</td><td>Top</td><td>117.95</td><td>123.16</td><td>2.122</td></tr><tr><td>m9</td><td>Bottom</td><td>119.45</td><td>124.66</td><td>2.142</td></tr><tr><td>m10</td><td>Matuyama/Gauss boundary</td><td></td><td>155.70</td><td>162.47</td><td>2.586</td></tr><tr><td>m11</td><td rowspan="2">Kaena</td><td>Top</td><td>192.90</td><td>201.61</td><td>3.043</td></tr><tr><td>m12</td><td>Bottom</td><td>201.70</td><td>210.63</td><td>3.108</td></tr></tbody></table>

<footnote>#Berggren et al. (1995); Shipboard Scientific Party (1999).</footnote>
**Table 4**

Nannofossil datum of ODP Hole 1115B. Depth (mbsf) are revised from Taylor et al. (2002).
<table><thead><tr><th colspan="2">Events</th><th rowspan="2">Nannofossil datum</th><th colspan="3">Top</th><th colspan="3">Bottom</th><th rowspan="2">mbsf (m)</th><th rowspan="2">Depth* (m)</th><th rowspan="2">Age (This study, Ma)</th></tr><tr><th>No.</th><th>Type</th><th>Core</th><th>Section</th><th>Interval (cm)</th><th>Core</th><th>Section</th><th>Interval (cm)</th></tr></thead><tbody><tr><td>n1</td><td>FO</td><td>Emiliania huxleyi</td><td>2H</td><td>2W</td><td>25-27</td><td>2H</td><td>2W</td><td>30-32</td><td>8.98 ± 0.03</td><td>8.93 ± 0.03</td><td>0.257 ± 0.001</td></tr><tr><td>n2</td><td>LO</td><td>Pseudoemiliania lacunosa</td><td>3H</td><td>1W</td><td>65-67</td><td>3H</td><td>1W</td><td>95-97</td><td>17.51 ± 0.15</td><td>17.98 ± 0.15</td><td>0.476 ± 0.003</td></tr><tr><td>n3</td><td>LO</td><td>Reticulofenestra asanoi</td><td>5H</td><td>2W</td><td>35-37</td><td>5H</td><td>2W</td><td>65-67</td><td>37.71 ± 0.15</td><td>39.36 ± 0.15</td><td>0.894 ± 0.004</td></tr><tr><td>n4</td><td></td><td>re-entrance of medium Gephyrocapsa</td><td>5H</td><td>6W</td><td>125-127</td><td>5H</td><td>7W</td><td>5-7</td><td>44.61 ± 0.15</td><td>46.26 ± 0.15</td><td>1.018 ± 0.002</td></tr><tr><td>n5</td><td>FO</td><td>Reticulofenestra asanoi</td><td>6H</td><td>3W</td><td>5-7</td><td>6H</td><td>3W</td><td>35-37</td><td>48.41 ± 0.15</td><td>50.69 ± 0.15</td><td>1.105 ± 0.001</td></tr><tr><td>n6</td><td>LO</td><td>large Gephyrocapsa</td><td>7H</td><td>1W</td><td>65-67</td><td>7H</td><td>1W</td><td>95-97</td><td>55.51 ± 0.15</td><td>58.31 ± 0.15</td><td>1.231 ± 0.002</td></tr><tr><td>n7</td><td>LO</td><td>Helicosphaera sellii</td><td>7H</td><td>3W</td><td>65-67</td><td>7H</td><td>3W</td><td>95-97</td><td>58.51 ± 0.15</td><td>61.31 ± 0.15</td><td>1.278 ± 0.002</td></tr><tr><td>n8</td><td>FO</td><td>large Gephyrocapsa</td><td>9H</td><td>3W</td><td>95-97</td><td>9H</td><td>3W</td><td>125-127</td><td>77.81 ± 0.15</td><td>81.56 ± 0.15</td><td>1.574 ± 0.001</td></tr><tr><td>n9</td><td>LO</td><td>Calcidiscus macintyrei</td><td>9H</td><td>4W</td><td>35-37</td><td>9H</td><td>4W</td><td>65-67</td><td>78.71 ± 0.15</td><td>82.46 ± 0.15</td><td>1.588 ± 0.003</td></tr><tr><td>n10</td><td>FO</td><td>medium Gephyrocapsa</td><td>10H</td><td>1W</td><td>95-97</td><td>10H</td><td>1W</td><td>125-127</td><td>84.31 ± 0.15</td><td>88.63 ± 0.15</td><td>1.700 ± 0.003</td></tr><tr><td>n11</td><td>LO</td><td>Discoaster brouweri</td><td>12H</td><td>1W</td><td>65-67</td><td>12H</td><td>1W</td><td>95-97</td><td>103.01 ± 0.15</td><td>108.02 ± 0.15</td><td>1.952 ± 0.002</td></tr></tbody></table>
<table><tr><td>n12</td><td>LO</td><td>Discoaster pentaradiatus</td><td>16H</td><td>5W</td><td>65-67</td><td>16H</td><td>5W</td><td>92-94</td><td>147.00 ± 0.14</td><td>153.24 ± 0.14</td><td>2.481 ± 0.002</td></tr><tr><td>n13</td><td>LO</td><td>Discoaster surculus</td><td>18H</td><td>5W</td><td>93-95</td><td>18H</td><td>5W</td><td>125-127</td><td>166.30 ± 0.16</td><td>173.56 ± 0.16</td><td>2.717 ± 0.002</td></tr><tr><td>n14</td><td>LO</td><td>Discoaster tamalis</td><td>19H</td><td>1W</td><td>35-37</td><td>19H</td><td>1W</td><td>70-72</td><td>169.24 ± 0.18</td><td>176.99 ± 0.18</td><td>2.757 ± 0.002</td></tr></table>
**Table 5**

<table><caption>Planktonic foraminiferal datum of ODP Hole 1115B.</caption><thead><tr><th colspan="2">Event</th><th rowspan="2">Planktonic<br>foraminiferal<br>datum</th><th colspan="3">Top</th><th colspan="3">Bottom</th><th rowspan="2">mbsf (m)</th><th rowspan="2">Depth* (m)</th><th rowspan="2">Age<br>(This study, Ma)</th></tr><tr><th>No.</th><th>Type</th><th>Core</th><th>Section</th><th>interval<br>(cm)</th><th>Core</th><th>Section</th><th>interval<br>(cm)</th></tr></thead><tbody><tr><td>f1<sup>a</sup></td><td>LO</td><td>Globigerinoides<br>ruber (pink)</td><td>1H</td><td>3W</td><td>55-57</td><td>1H</td><td>3W</td><td>60-62</td><td>3.59 ± 0.03</td><td>3.59± 0.03</td><td>0.127 ± 0.001</td></tr><tr><td>f2<sup>a</sup></td><td>LO</td><td>Globigerinoides<br>fistulosus</td><td>10H</td><td>3W</td><td>95-97</td><td>10H</td><td>4W</td><td>5-7</td><td>87.41 ± 0.30</td><td>91.78 ± 0.30</td><td>1.737 ± 0.003</td></tr><tr><td>f3<sup>b</sup></td><td>TOP</td><td>Pulleniatina spp.</td><td>10H</td><td>5W</td><td>95-97</td><td>10H</td><td>5W</td><td>125-127</td><td>90.31 ± 0.15</td><td>94.63 ± 0.15</td><td>1.777 ± 0.003</td></tr><tr><td>f4<sup>b</sup></td><td>Bottom</td><td>Left coiling<br>event 5 (L5)</td><td>13H</td><td>6W</td><td>35-37</td><td>13H</td><td>6W</td><td>95-97</td><td>119.86 ± 0.30</td><td>124.92 ± 0.30</td><td>2.147 ± 0.004</td></tr><tr><td>f5<sup>a</sup></td><td>LO</td><td>Dentoglobigerina<br>altispira</td><td>21H</td><td>4W</td><td>93-95</td><td>21H</td><td>4W</td><td>125-127</td><td>193.30 ± 0.16</td><td>202.01 ± 0.16</td><td>3.046 ± 0.001</td></tr></tbody></table>

<footnote><sup>a</sup>Revised from Taylor et al. (2002).</footnote>

<footnote><sup>b</sup>This study</footnote>
<caption>**Table 6**</caption>

Comparison of nannofossil and planktonic foraminifera biostratigraphic datum from different regions.

<table><thead><tr><th colspan="2">Event</th><th rowspan="2">Nannofossil datum</th><th rowspan="2">Age (Ma, this study)</th><th colspan="3">Age (Ma) as reported from different regions</th></tr><tr><th>No.</th><th>Type</th><th>East Equatorial Pacific<sup>a,g</sup></th><th>West Atlantic Ocean<sup>a,g</sup></th><th>Eastern Mediterranean<sup>a,g</sup></th></tr></thead><tbody><tr><td>n1</td><td>FO</td><td><i>E. huxleyi</i></td><td>0.257 ± 0.001</td><td>0.291</td><td>0.289</td><td>0.265</td></tr><tr><td>n2</td><td>LO</td><td><i>P. lacunosa</i></td><td>0.476 ± 0.003</td><td>0.436</td><td>0.440</td><td>0.467</td></tr><tr><td>n3</td><td>LO</td><td><i>R. asanoi</i></td><td>0.894 ± 0.004</td><td>-</td><td>0.905</td><td>0.901</td></tr><tr><td>n4</td><td></td><td>re-entrance of medium <i>Gephyrocapsa</i></td><td>1.018 ± 0.002</td><td>1.04</td><td>1.007</td><td>0.956-0.985</td></tr><tr><td>n5</td><td>FO</td><td><i>R. asanoi</i></td><td>1.105 ± 0.001</td><td>-</td><td>1.136</td><td>1.078</td></tr><tr><td>n6</td><td>LO</td><td>large <i>Gephyrocapsa</i></td><td>1.231 ± 0.002</td><td>1.24</td><td>1.255</td><td>1.245</td></tr><tr><td>n7</td><td>LO</td><td><i>H. sellii</i></td><td>1.278 ± 0.002</td><td>1.34</td><td>-</td><td>1.256</td></tr><tr><td>n8</td><td>FO</td><td>large <i>Gephyrocapsa</i></td><td>1.574 ± 0.001</td><td>1.46</td><td>1.56</td><td>1.617</td></tr><tr><td>n9</td><td>LO</td><td><i>C. macintyrei</i></td><td>1.588 ± 0.003</td><td>1.60</td><td>1.607</td><td>1.664</td></tr><tr><td>n10</td><td>FO</td><td>medium <i>Gephyrocapsa</i></td><td>1.700 ± 0.003</td><td>1.67</td><td>1.689</td><td>1.730</td></tr><tr><td>n11</td><td>LO</td><td><i>D. brouweri</i></td><td>1.952 ± 0.002</td><td>2.06</td><td>1.926</td><td>1.950</td></tr><tr><td>n12</td><td>LO</td><td><i>D. pentaradiatus</i></td><td>2.481 ± 0.002</td><td>2.46 ± 0.02<sup>k</sup></td><td>2.393</td><td>2.512</td></tr><tr><td>n13</td><td>LO</td><td><i>D. surculus</i></td><td>2.717 ± 0.002</td><td>2.52</td><td>2.485</td><td>2.539</td></tr><tr><td>n14</td><td>LO</td><td><i>D. tamalis</i></td><td>2.757 ± 0.002</td><td>2.87</td><td>2.801</td><td>2.8</td></tr></tbody></table>

Planktonic foraminiferal datum
<table><tr><td>f1</td><td>LO</td><td>G. ruber (pink)</td><td>0.127 ± 0.001</td><td>0.12<sup>b,c</sup></td><td>-</td><td>-</td></tr><tr><td>f2</td><td>LO</td><td>G. fistulosus</td><td>1.737 ± 0.003</td><td>1.77<sup>h,i</sup></td><td>1.88<sup>c,d</sup></td><td>-</td></tr><tr><td>f3</td><td>TOP</td><td>Pulleniatina spp. Left coiling</td><td>1.777 ± 0.003</td><td>1.77<sup>f,g</sup></td><td>-</td><td>-</td></tr><tr><td>f4</td><td>Bottom</td><td>event 5 (L5)</td><td>2.147 ± 0.004</td><td>2.05<sup>f,g</sup>, 2.09<sup>f,g</sup></td><td>-</td><td>-</td></tr><tr><td>f5</td><td>LO</td><td>D. altispira</td><td>3.046 ± 0.001</td><td>3.46<sup>c,j</sup></td><td>3.13<sup>c,d,h</sup></td><td>3.17<sup>h</sup></td></tr></table>

<sup>a</sup>Raffi et al. (2006) and references therein

<sup>b</sup>Thompson et al. (1979)

<sup>c</sup>Wade et al., (2011)

<sup>d</sup>Chaisson and Pearson (1997)

<sup>e</sup>Berggren et al. (1995)

<sup>f</sup>Woodlark Basin sites from Resig et al. (2001)

<sup>g</sup>Central Pacific sites from Hays et al. (1969), Saito et al. (1975), and Saito (1976)

<sup>h</sup>Anthonissen and Ogg (2012)

<sup>i</sup>Jenkins and Houghton (1989)

<sup>j</sup>Shackleton et al. (1995b)

<sup>k</sup>ODP site 677 base on biostratigraphy from Wei (1993) and δ<sup>18</sup>O stratigraphy from Shackleton et al., (1990)