**Seismic Operations During Cruise IMAGES VIII, MONA/PAGE 2002,
D-1-02-GM Cruise of the R/V Marion Dufresne in the Northern Gulf of
Mexico**

**Patrick E. Hart and Thomas D. Lorenson**

High-resolution chirp seismic refection profiles were collected at most
of the 2002 core sites using a hull-mounted Thales Sea Falcon II chirp
seismic system, using a 25 ms chirp source with a 1600 Hz bandwidth
centered at 3.75 kHz. The system was operating almost continuously
during the cruise, recording approximately 600 files in standard
geophysical 16-bit SEG-Y format, which were later concatenated into 12
larger files. The 40 SEG-Y files available on the USGS website,
<http://walrus.wr.usgs.gov/infobank/d/d102gm/html/d-1-02-gm.meta.html>
were taken from these 12 files and comprise the tracklines designed to
pass through and adjacent to the coring sites. The final SEG-Y data
files each contain a SEG-Y EBCDIC file header (shown below) listing
important information about the data and the data trace headers. The
most important trace header information is longitude and latitude, given
as 4 byte integers in trace header locations bytes 191-194 and 195-198,
respectively. The values are decimal degrees, with five decimal places,
multiplied by 100,000 to allow the values to remain integer. For
example, a latitude of 27.29863 degrees will be recorded in the trace
header as 2729863.

**Table 1.** SEG-Y EBCDIC header.

\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*

\* EBCDIC REEL HEADER \*

\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*

C 1 U. S. GEOLOGICAL SURVEY COASTAL AND MARINE GEOLOGY TEAM

C 2 SURVEY_ID: D1-02-GM YEAR: 2002

C 3 AREA: NORTHERN GULF OF MEXICO VESSEL: R/V MARION DUFRESNE

C 4

C 5 INSTRUMENT: THALES UNDERWATER SYSTEMS SEAFALCON II CHIRP SEISMIC

C 6 25 MS CHIRP LENGTH 1600 HZ BANDWIDTH CENTERED AT 3.75KHZ

C 7 LINEAR FREQUENCY MODULATED CHIRP

C 8 RECORDING PARAMETERS: CHANNELS PER SHOT: 1

C 9 SAMPLE INTERVAL: 417 MICROSEC SAMPLE FREQUENCY: 2.4KHZ

C10 SAMPLES/TRACE: 2048 DATA LENGTH: 850 MSEC

C11 RECORD LENGTH VARIES WITH DEEP WATER DELAY PLUS DATA LENGTH

C12 DATA TRACE IS AMPLITUDE ENVELOPE; POSITIVE VALUES ONLY

C13

C14

C15 RECORDING FORMAT:

C16 SEG-Y 16-BIT INTEGER

C17 IMPORTANT TRACE HEADER VALUE LOCATIONS:

C18 NAME BYTES TYPE DESCRIPTION

C19 FFID 9-12 INTEGER FIELD FILE, SHOT OR PING NUMBER

C20 CDP 21-24 INTEGER SAME AS FFID

C21

C22 TYPE 29-30 INTEGER TRACE IDENTIFFICATION CODE

C23

C24

C25 DELAY 109-110 INTEGER DELAY RECORDING TIME IN MILLISEC

C26 NSAMPLES 115-116 INTEGER NUMBER OF SAMPLES IN THIS TRACE

C27 SRATE 117-118 INTEGER SAMPLE INTERVAL IN MICROSEC FOR THIS TRACE

C28 YEAR 157-158 INTEGER YEAR DATA RECORDED

C29 DAY 159-160 INTEGER DAY OF YEAR

C30 HOUR 161-162 INTEGER HOUR (24-HOUR CLOCK)

C31 MINUTE 163-164 INTEGER MINUTE

C32 SECOND 165-166 INTEGER SECOND

C33 LONGITUDE 191-194 INTEGER DECIMAL DEGREES TIMES 100000

C34 LATITUDE 195-198 INTEGER DECIMAL DEGREES TIMES 100000

C35

C36 FOR FURTHER INFORMATION CONCERNING THIS DATASET, CONTACT:

C37 PATRICK HART

C38 U. S. GEOLOGICAL SURVEY, M/S 999

C39 345 MIDDLEFIELD RD., MENLO PARK, CALIFORNIA 94025

C40 (650) 329-5160 INTERNET: HART@USGS.GOV

The SEG-Y data traces are the calculated amplitude envelope attribute
showing positive values only, as opposed to a conventional wiggle trace
with positive and negative values. The firing or chirp interval during
data acquisition was 1.3 seconds for lines SP1b, SP2 and SP3 and 4.3
seconds for lines SP15 and SP16. For all other lines this interval was
3.5 seconds. Sample interval of the data is 417 microseconds with 2048
samples per trace, giving a data length of 850 milliseconds. The data
were recorded with a variable deep-water delay calculated in real-time
based on the water depth. In theory, this will give a constant record
length below seafloor, but in practice the bottom-tracking feature
occasionally loses the bottom and this causes skipped or blank traces in
the final display. This is evident on some of the Tiff image files of
the seismic lines, such as line SP15 or SP33a. The SEG-Y files are
output with the deep-water delay applied.

In addition to the SEG-Y format files, a Tiff image file of each seismic
line is available on the USGS website
<http://walrus.wr.usgs.gov/infobank/d/d102gm/html/d-1-02-gm.meta.html>.
These are grayscale Tiff format files with LZW compression. The display
parameters of the data in these Tiff files are 15 inches/second and
either 40 or 100 traces/inch. The horizontal scale is dependent on the
chirp interval, ship speed and the traces/inch of the plot. To
accurately determine horizontal distance along one of these seismic
profiles, refer to the navigation file (D102GM_lines.xls) available on
the USGS website
<http://walrus.wr.usgs.gov/infobank/d/d102gm/html/d-1-02-gm.meta.html>.
This spreadsheet lists position in decimal degrees versus time in GMT at
7 to 12 second intervals along each profile. A good estimate of
horizontal scale for each line can be determined from the line summary
table below, which lists line length and plotting parameters.

GMT is listed along the top of each seismic profile as hhmmss
(hour,minute,second). Time is also in the standard SEG-Y trace header
locations as described in the EBCDIC header. All of the profiles are
plotted with north and west on the left. Two-way reflection time in 10
ms intervals is listed along the sides of the seismic profiles in the
Tiff images. Using a seismic velocity of 1500 m/s, each 10 ms represents
approximately 7.5 meters of sediment. A reduced image of line SP17, a
west-to-east profile crossing Bush Hill, is shown below in Figure 2a.

![](media/image1.png){width="7.091666666666667in"
height="3.884027777777778in"}

**Fig. 2a.** This image of seismic line SP17 was modified from the tiff
image SP17.tif available on the USGS website
<http://walrus.wr.usgs.gov/infobank/d/d102gm/html/d-1-02-gm.meta.html>.
The size was reduced to fit on the page, and the title, scale bars, and
the locations of cores MD02-2564, 2565, and 2566 were added. The data
show good signal-to-noise ratio and approximately 100 to 150 m
penetration into the soft sediments adjacent to the mound at the
left-center of the figure. There is very little imaging beneath the hard
carbonate and gas hydrate that occurs at the surface of this and similar
mounds in the region. The location of this profile is shown on the Bush
Hill map in Fig 4. At this reduced scale the GMT and two-way reflection
time labels are not visible. The boxed area is expanded below in Figure
2b.

![](media/image2.png){width="6.125in" height="7.364583333333333in"}

**Figure 2b**. This expanded view of a portion of line SP17 allows the
GMT and reflection time labels to be read. Two-way reflection time from
600 ms to 840 ms in 10 ms intervals is labeled along the left and GMT
from hour 16, minute 55, second 08 to hour 17, minute 00, second 56 is
labeled along the top from right to left. The 35 second GMT label
interval represents 10 traces at a 3.5 second chirp interval. This
labeling is on all the Tiff image files.

Collecting geophysical data was not the highest cruise priority so the
seismic coverage at each core site depends on the time available between
coring operations. Trackline maps for the six areas where seismic data
were acquired are shown in figures 3 through 8. The initial series of
seismic lines at Tunica mound were poorly navigated and many lines were
run in a fairly small area. As a result the lines are not straight and
cross back and forth over each other. Figure 3a shows all the Tunica
lines and figures 9b and 9c each plot a subset of the lines in order to
be more legible. An additional problem with the Tunica lines is that the
primary navigation recording system was not operating during the
acquisition of lines SP1 to SP3, and lines SP6 through SP10. The
navigation fixes for these lines were taken from the SEG-Y trace headers
as described above. The precision of the fixes (approximately 10 m) in
the trace headers is not as high as with the primary system
(approximately 1 m) and therefore these lines appear to be choppier than
the others when plotted at a large scale.

A table of information on all the chirp seismic lines is listed below
and included on this CD in file "line_summary.xls". Three of the
recovered cores do not have corresponding chirp seismic lines that pass
near their locations. For these cores, MD02-2566, 2567 and 2567, files
were made of the chirp data recorded while the ship was drifting during
coring operations. These are listed as lines 24d, 25d, and 33d.

**Table 2**. Chirp seismic reflection line summary

<table>
<colgroup>
<col style="width: 7%" />
<col style="width: 15%" />
<col style="width: 8%" />
<col style="width: 7%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 8%" />
<col style="width: 10%" />
<col style="width: 10%" />
<col style="width: 10%" />
</colgroup>
<tbody>
<tr class="odd">
<td><strong>Line</strong></td>
<td><h2 id="area">Area</h2></td>
<td><strong>Length</strong></td>
<td><strong>JD</strong></td>
<td><strong>Start time</strong></td>
<td><strong>End time</strong></td>
<td><strong>Number</strong></td>
<td><strong>Tiff Scale</strong></td>
<td><strong>Line scale</strong></td>
<td><strong>Ave speed</strong></td>
</tr>
<tr class="even">
<td><strong>no.</strong></td>
<td></td>
<td><strong>km</strong></td>
<td></td>
<td><strong>hour-min</strong></td>
<td><strong>hour-min</strong></td>
<td><strong>traces</strong></td>
<td><strong>inch/km</strong></td>
<td><strong>traces/km</strong></td>
<td><strong>kts</strong></td>
</tr>
<tr class="odd">
<td>1a</td>
<td>Tunica Mound</td>
<td>2.6</td>
<td>185</td>
<td>1812</td>
<td>1818</td>
<td>106</td>
<td>1.0</td>
<td>40.8</td>
<td>14.0</td>
</tr>
<tr class="even">
<td>1b</td>
<td>Tunica Mound</td>
<td>7.3</td>
<td>185</td>
<td>1818</td>
<td>1838</td>
<td>916</td>
<td>1.3</td>
<td>125.5</td>
<td>11.8</td>
</tr>
<tr class="odd">
<td>2</td>
<td>Tunica Mound</td>
<td>10.7</td>
<td>185</td>
<td>1841</td>
<td>1921</td>
<td>1850</td>
<td>1.7</td>
<td>172.9</td>
<td>8.7</td>
</tr>
<tr class="even">
<td>3</td>
<td>Tunica Mound</td>
<td>4.6</td>
<td>185</td>
<td>1937</td>
<td>1956</td>
<td>856</td>
<td>1.9</td>
<td>186.1</td>
<td>7.8</td>
</tr>
<tr class="odd">
<td>4</td>
<td>Tunica Mound</td>
<td>2.8</td>
<td>186</td>
<td>403</td>
<td>422</td>
<td>861</td>
<td>3.1</td>
<td>307.5</td>
<td>4.8</td>
</tr>
<tr class="even">
<td>5</td>
<td>Tunica Mound</td>
<td>3.6</td>
<td>186</td>
<td>433</td>
<td>500</td>
<td>1227</td>
<td>3.4</td>
<td>340.8</td>
<td>4.3</td>
</tr>
<tr class="odd">
<td>6</td>
<td>Tunica Mound</td>
<td>4.1</td>
<td>187</td>
<td>910</td>
<td>938</td>
<td>483</td>
<td>2.9</td>
<td>117.8</td>
<td>4.7</td>
</tr>
<tr class="even">
<td>7</td>
<td>Tunica Mound</td>
<td>3.0</td>
<td>187</td>
<td>941</td>
<td>959</td>
<td>311</td>
<td>2.6</td>
<td>103.7</td>
<td>5.4</td>
</tr>
<tr class="odd">
<td>8</td>
<td>Tunica Mound</td>
<td>2.5</td>
<td>187</td>
<td>1228</td>
<td>1246</td>
<td>309</td>
<td>3.1</td>
<td>123.6</td>
<td>4.5</td>
</tr>
<tr class="even">
<td>9</td>
<td>Tunica Mound</td>
<td>2.1</td>
<td>187</td>
<td>1252</td>
<td>1304</td>
<td>207</td>
<td>2.5</td>
<td>98.6</td>
<td>5.7</td>
</tr>
<tr class="odd">
<td>10</td>
<td>Tunica Mound</td>
<td>2.2</td>
<td>187</td>
<td>1312</td>
<td>1328</td>
<td>274</td>
<td>3.1</td>
<td>124.5</td>
<td>4.5</td>
</tr>
<tr class="even">
<td>11</td>
<td>Tunica Mound</td>
<td>2.2</td>
<td>187</td>
<td>1344</td>
<td>1358</td>
<td>241</td>
<td>2.7</td>
<td>109.5</td>
<td>5.1</td>
</tr>
<tr class="odd">
<td>12</td>
<td>Tunica Mound</td>
<td>1.0</td>
<td>187</td>
<td>1423</td>
<td>1431</td>
<td>138</td>
<td>3.5</td>
<td>138.0</td>
<td>4.0</td>
</tr>
<tr class="even">
<td>13</td>
<td>Tunica Mound</td>
<td>1.2</td>
<td>187</td>
<td>1439</td>
<td>1446</td>
<td>121</td>
<td>2.5</td>
<td>100.8</td>
<td>5.6</td>
</tr>
<tr class="odd">
<td>14</td>
<td>Tunica Mound</td>
<td>2.1</td>
<td>187</td>
<td>1653</td>
<td>1731</td>
<td>656</td>
<td>7.8</td>
<td>312.4</td>
<td>1.8</td>
</tr>
<tr class="even">
<td>15</td>
<td>Pigmy Basin</td>
<td>6.7</td>
<td>190</td>
<td>537</td>
<td>620</td>
<td>603</td>
<td>2.3</td>
<td>90.0</td>
<td>5.0</td>
</tr>
<tr class="odd">
<td>16</td>
<td>Pigmy Basin</td>
<td>5.4</td>
<td>190</td>
<td>644</td>
<td>716</td>
<td>449</td>
<td>2.1</td>
<td>83.1</td>
<td>5.5</td>
</tr>
<tr class="even">
<td>17</td>
<td>Bush Hill</td>
<td>6.0</td>
<td>190</td>
<td>1625</td>
<td>1701</td>
<td>610</td>
<td>2.5</td>
<td>101.7</td>
<td>5.4</td>
</tr>
<tr class="odd">
<td>18</td>
<td>Bush Hill</td>
<td>3.0</td>
<td>190</td>
<td>1722</td>
<td>1739</td>
<td>293</td>
<td>2.4</td>
<td>97.7</td>
<td>5.7</td>
</tr>
<tr class="even">
<td>19</td>
<td>Bush Hill</td>
<td>2.8</td>
<td>190</td>
<td>1746</td>
<td>1802</td>
<td>276</td>
<td>2.5</td>
<td>98.6</td>
<td>5.7</td>
</tr>
<tr class="odd">
<td>20</td>
<td>Bush Hill</td>
<td>2.2</td>
<td>190</td>
<td>1813</td>
<td>1828</td>
<td>259</td>
<td>2.9</td>
<td>117.7</td>
<td>4.8</td>
</tr>
<tr class="even">
<td>21a</td>
<td>Kane Spur</td>
<td>21.0</td>
<td>192</td>
<td>444</td>
<td>646</td>
<td>2001</td>
<td>1.0</td>
<td>95.3</td>
<td>5.9</td>
</tr>
<tr class="odd">
<td>21b</td>
<td>Kane Spur</td>
<td>19.3</td>
<td>192</td>
<td>935</td>
<td>1120</td>
<td>1811</td>
<td>0.9</td>
<td>93.8</td>
<td>6.0</td>
</tr>
<tr class="even">
<td>22a</td>
<td>Kane Spur</td>
<td>9.6</td>
<td>192</td>
<td>1224</td>
<td>1326</td>
<td>1070</td>
<td>1.1</td>
<td>111.5</td>
<td>5.0</td>
</tr>
<tr class="odd">
<td>22b</td>
<td>Kane Spur</td>
<td>26.4</td>
<td>192</td>
<td>1650</td>
<td>1919</td>
<td>2569</td>
<td>1.0</td>
<td>97.3</td>
<td>5.7</td>
</tr>
<tr class="even">
<td>23a</td>
<td>Kane Spur</td>
<td>31.1</td>
<td>193</td>
<td>35</td>
<td>308</td>
<td>2639</td>
<td>0.8</td>
<td>84.9</td>
<td>6.6</td>
</tr>
<tr class="odd">
<td>23b</td>
<td>Kane Spur</td>
<td>5.5</td>
<td>193</td>
<td>530</td>
<td>604</td>
<td>580</td>
<td>1.1</td>
<td>105.5</td>
<td>5.2</td>
</tr>
<tr class="even">
<td>24</td>
<td>Kane Spur</td>
<td>27.4</td>
<td>193</td>
<td>649</td>
<td>908</td>
<td>2398</td>
<td>0.9</td>
<td>87.5</td>
<td>6.4</td>
</tr>
<tr class="odd">
<td>24d</td>
<td>Kane Spur</td>
<td>drift</td>
<td>194</td>
<td>900</td>
<td>930</td>
<td>517</td>
<td>drift</td>
<td>drift</td>
<td>drift</td>
</tr>
<tr class="even">
<td>25</td>
<td>Kane Spur</td>
<td>23.0</td>
<td>194</td>
<td>342</td>
<td>542</td>
<td>2067</td>
<td>0.9</td>
<td>89.9</td>
<td>6.2</td>
</tr>
<tr class="odd">
<td>25d</td>
<td>Kane Spur</td>
<td>drift</td>
<td>194</td>
<td>1457</td>
<td>1527</td>
<td>485</td>
<td>drift</td>
<td>drift</td>
<td>drift</td>
</tr>
<tr class="even">
<td>26</td>
<td>West MC</td>
<td>10.8</td>
<td>195</td>
<td>622</td>
<td>722</td>
<td>1035</td>
<td>1.0</td>
<td>95.8</td>
<td>5.8</td>
</tr>
<tr class="odd">
<td>27</td>
<td>West MC</td>
<td>4.8</td>
<td>195</td>
<td>1220</td>
<td>1252</td>
<td>552</td>
<td>1.2</td>
<td>115.0</td>
<td>4.9</td>
</tr>
<tr class="even">
<td>28</td>
<td>West MC</td>
<td>6.0</td>
<td>195</td>
<td>1303</td>
<td>1340</td>
<td>638</td>
<td>1.1</td>
<td>106.3</td>
<td>5.3</td>
</tr>
<tr class="odd">
<td>29</td>
<td>West MC</td>
<td>10.7</td>
<td>195</td>
<td>1925</td>
<td>2023</td>
<td>1000</td>
<td>0.9</td>
<td>93.5</td>
<td>6.0</td>
</tr>
<tr class="even">
<td>30</td>
<td>West MC</td>
<td>11.1</td>
<td>195</td>
<td>2035</td>
<td>2143</td>
<td>1172</td>
<td>1.1</td>
<td>105.6</td>
<td>5.3</td>
</tr>
<tr class="odd">
<td>31</td>
<td>West MC</td>
<td>6.6</td>
<td>195</td>
<td>2149</td>
<td>2225</td>
<td>621</td>
<td>0.9</td>
<td>94.1</td>
<td>5.9</td>
</tr>
<tr class="even">
<td>32</td>
<td>Central MC</td>
<td>6.4</td>
<td>195</td>
<td>219</td>
<td>242</td>
<td>396</td>
<td>0.6</td>
<td>61.9</td>
<td>9.0</td>
</tr>
<tr class="odd">
<td>32d</td>
<td>Central MC</td>
<td>drift</td>
<td>195</td>
<td>335</td>
<td>405</td>
<td>517</td>
<td>drift</td>
<td>drift</td>
<td>drift</td>
</tr>
<tr class="even">
<td>33a</td>
<td>Central MC</td>
<td>9.5</td>
<td>196</td>
<td>37</td>
<td>105</td>
<td>483</td>
<td>0.5</td>
<td>50.8</td>
<td>11.0</td>
</tr>
<tr class="odd">
<td>33b</td>
<td>Central MC</td>
<td>0.9</td>
<td>196</td>
<td>212</td>
<td>250</td>
<td>655</td>
<td>7.3</td>
<td>727.8</td>
<td>0.8</td>
</tr>
</tbody>
</table>

The two tables below are a summary of all the *Marion Dufresne* cores
and are combined in the spreadsheet file on this CD "core_seismic.xls".
The one or two chirp seismic lines that pass over or near each core are
listed with the core location along the line in time (GMT).

**Table 3**. Seismic reflection line ties with core locations.

  ---------------- -------------- --------------- -------------------- --------------------
  **CORE ID**      **Latitude**   **Longitude**   **Chirp Seismic Tie  **Chirp Seismic Tie
                                                  1**                  2**

                                                  **distance from line **distance from line
                                                  to core**            to core**

                                                                       

  MD02-2535        27.61983       -92.24100       SP2; 185 190955; 10  SP11; 187 135555; on
                                                  m N                  line

  MD02-2536GHF-1   27.62268       -92.24378       SP12;187 142955; on  SP8; 187 123210; 20
                                                  line                 m NW

  MD02-2536GHF-2   27.62530       -92.24600       SP12; 187 143100;    none
                                                  220 m NW             

  MD02-2536GHF-3   27.62700       -92.23750       SP7; 187 95640; 170  none
                                                  m N                  

  Μ∆02−2537        27.61600       -92.24867       SP1a; 185 181435; on SP2; 185 191310; 30
                                                  line                 m NW

  MD02-2538G       27.61667       -92.24717       SP1a; 185 181500; 20 SP2; 185 191235; 30
                                                  m N                  m N

  MD02-2539        27.63983       -92.19226       SP2; 185 184940; 80  none
                                                  m N                  

  MD02-2540GHF-1   27.64008       -92.19201       SP2; 185 184935; 100 none
                                                  m N                  

  MD02-2540GHF-2   27.64017       -92.19533       SP2; 185 185050; 190 none
                                                  m N                  

  MD02-2541        27.63244       -92.21245       SP2; 185 185750; 160 none
                                                  m NW                 

  MD02-2542GHF     27.63212       -92.21242       SP2; 185 185750; 140 none
                                                  m NW                 

  MD02-2543G       27.61253       -92.25565       SP1a; 185 181250; 50 none
                                                  m SE                 

  MD02-2544G       27.61315       -92.25336       SP10; 187 132425; 20 SP2; 185 191520; 30
                                                  m N                  m N

  MD02-2545G       27.61416       -92.25177       SP10 187 132255; on  SP2; 185 191435; 20
                                                  line                 m NW

  MD02-2546        27.61567       -92.24697       SP11; 187 135125; 30 SP2; 185 191245; 80
                                                  m SE                 m SE

  MD02-2547GHF     27.61642       -92.24832       SP1a; 185 181445; 30 SP2; 185 191300; 60
                                                  m NW                 m NW

  MD02-2553C2      27.18340       -91.41694       SP15; 190 55650; on  SP16; 190 65950; 40
                                                  line                 m N

  MD02-2554        27.78371       -91.49967       SP17; 190 164820; on SP18; 190 172810; 50
                                                  line                 m E

  MD02-2555        27.78320       -91.48901       SP17; 190 164210; 50 SP19; 190 175540; on
                                                  m S                  line

  MD02-2556        27.78300       -91.47809       SP17; 190 163520;90  SP20; 190 182010; 30
                                                  m S                  m W

  MD02-2557GHF1    27.78304       -91.49862       SP17; 190 164740; 70 SP18; 190 172830;
                                                  m S                  150 m E

  MD02-2557GHF2    27.78310       -91.48904       SP17; 190 164210; 50 SP19; 190 175540; on
                                                  m S                  line

  MD02-2557GHF3    27.78288       -91.47720       SP17; 190 163445;    SP20; 190 182015; 50
                                                  100 m S              m E

  MD02-2559        28.22267       -89.08784       SP21a; 192 62815; on SP25; 194 53730; 60
                                                  line                 m SE

  MD02-2560        28.24361       -89.15503       SP21a; 192 54910; 40 none
                                                  m N                  

  MD02-2561        28.20530       -89.02016       SP21b; 192 100640;   SP23a; 193 13540; 20
                                                  20 m N               m NW

  MD02-2562        28.07997       -89.14030       SP23a; 193 30800;    none
                                                  170 m SW             

  MD02-2563C2      28.12354       -89.13651       SP24; 193 72140; 230 none
                                                  m N                  

  MD02-2564GHFa    28.24347       -89.15464       SP21a; 192 54925; 40 none
                                                  m N                  

  MD02-2564GHFb    28.22257       -89.08861       SP25; 194 53710; 10  SP21a; 192 62755; 50
                                                  m SE                 m SW

  MD02-2564GHFc    28.20545       -89.02014       SP21b; 192 100640;   SP23a; 193 13535; 30
                                                  30 m N               m NW

  MD02-2564GHFd    28.20733       -89.02019       SP23a; 193 13450;    none
                                                  170 m NW             

  MD02-2565        28.12361       -89.13971       SP24; 193 72000; 130 none
                                                  m N                  

  MD02-2566        28.11927       -89.10339       SP23a; 193 235 30;   SP24d; 194 91630; on
                                                  660 m NW             line

  MD02-2567        28.10037       -89.02007       SP24; 193 82700;     SP25d; 194 151730;
                                                  1750 m NE            on line

  MD02-2568GHFa    28.07992       -89.14030       SP23a; 193 30800;    none
                                                  170 m SW             

  MD02-2568GHFb    28.08107       -89.13717       SP23a; 193 30610;    none
                                                  100 m SE             

  MD02-2568GHFc    28.11936       -89.10331       SP23a; 193 235 30;   SP24d; 194 92850; on
                                                  660 m NW             line

  MD02-2568GHFd    28.12347       -89.13952       SP24; 193 72010; 120 none
                                                  m N                  

  MD02-2568GHFe    28.12354       -89.13636       SP24; 193 72150; 240 none
                                                  m N                  

  MD02-2569        28.15218       -89.47980       SP33b; 196 21200; 20 SP32d; 195 33800; on
                                                  m SW                 line

  MD02-2570        28.07107       -89.68997       SP26; 195 65720; 20  SP31; 195 222450; 60
                                                  m S                  m NW

  MD02-2571C2      28.06681       -89.72007       SP26; 195 64020; 90  SP28; 195 132315;
                                                  m S                  150 m W

  MD02-2572GHF     28.07109       -89.69001       SP26; 195 65720; 20  SP31; 195 222450; 60
                                                  m S                  m NW

  MD02-2573GHF     28.15204       -89.48004       SP33b; 196 21200; 50 SP32d; 195 34200; on
                                                  m SW                 line
  ---------------- -------------- --------------- -------------------- --------------------

**Table 4.** Recovered core summary

  ---------------- -------------- --------------- ------------- ------------ ------------
  **CORE ID**      **Latitude**   **Longitude**   **Site Name** **Core       **Water
                                                                Length**     Depth**

                                                                **meters**   **meters**

                                                                             

  MD02-2535        27.61983       -92.24100       Tunica Mound  37.84        605

  MD02-2536GHF-1   27.62268       -92.24378       Tunica Mound  8.88         608

  MD02-2536GHF-2   27.62530       -92.24600       Tunica Mound  none         564

  MD02-2536GHF-3   27.62700       -92.23750       Tunica Mound  none         585

  Μ∆02−2537        27.61600       -92.24867       Tunica Mound  33.58        600

  MD02-2538G       27.61667       -92.24717       Tunica Mound  7.76         599

  MD02-2539        27.63983       -92.19226       Tunica Mound  31.10        622

  MD02-2540GHF-1   27.64008       -92.19201       Tunica Mound  5.65         617

  MD02-2540GHF-2   27.64017       -92.19533       Tunica Mound  none         620

  MD02-2541        27.63244       -92.21245       Tunica Mound  35.34        615

  MD02-2542GHF     27.63212       -92.21242       Tunica Mound  7.70         617

  MD02-2543G       27.61253       -92.25565       Tunica Mound  0.15         579

  MD02-2544G       27.61315       -92.25336       Tunica Mound  0.10         584

  MD02-2545G       27.61416       -92.25177       Tunica Mound  9.27         588

  MD02-2546        27.61567       -92.24697       Tunica Mound  31.21        595

  MD02-2547GHF     27.61642       -92.24832       Tunica Mound  5.73         607

  MD02-2553C2      27.18340       -91.41694       Pigmy Basin   10.32        2259

  MD02-2554        27.78371       -91.49967       Bush Hill     31.05        602

  MD02-2555        27.78320       -91.48901       Bush Hill     35.68        636

  MD02-2556        27.78300       -91.47809       Bush Hill     34.25        654

  MD02-2557GHF1    27.78304       -91.49862       Bush Hill     5.59         613

  MD02-2557GHF2    27.78310       -91.48904       Bush Hill     none         639

  MD02-2557GHF3    27.78288       -91.47720       Bush Hill     none         659

  MD02-2559        28.22267       -89.08784       Kane Spur     33.39        1132

  MD02-2560        28.24361       -89.15503       Kane Spur     28.24        1029

  MD02-2561        28.20530       -89.02016       Kane Spur     28.80        1268

  MD02-2562        28.07997       -89.14030       Kane Spur     26.09        1051

  MD02-2563C2      28.12354       -89.13651       Kane Spur     3.86         1070

  MD02-2564GHFa    28.24347       -89.15464       Kane Spur     7.63         1027

  MD02-2564GHFb    28.22257       -89.08861       Kane Spur     none         1261

  MD02-2564GHFc    28.20545       -89.02014       Kane Spur     none         1269

  MD02-2564GHFd    28.20733       -89.02019       Kane Spur     none         1269

  MD02-2565        28.12361       -89.13971       Kane Spur     22.50        1068

  MD02-2566        28.11927       -89.10339       Kane Spur     26.05        1186

  MD02-2567        28.10037       -89.02007       Kane Spur     26.65        1318

  MD02-2568GHFa    28.07992       -89.14030       Kane Spur     6.96         1049

  MD02-2568GHFb    28.08107       -89.13717       Kane Spur     none         1057

  MD02-2568GHFc    28.11936       -89.10331       Kane Spur     none         1190

  MD02-2568GHFd    28.12347       -89.13952       Kane Spur     none         1068

  MD02-2568GHFe    28.12354       -89.13636       Kane Spur     none         1049

  MD02-2569        28.15218       -89.47980       Central Miss  10.35        1032

  MD02-2570        28.07107       -89.68997       West MC       28.35        631

  MD02-2571C2      28.06681       -89.72007       West MC       10.38        664

  MD02-2572GHF     28.07109       -89.69001       West MC       4.90         628

  MD02-2573GHF     28.15204       -89.48004       Central MC    4.20         1027
  ---------------- -------------- --------------- ------------- ------------ ------------

![](media/image3.png){width="7.088888888888889in"
height="4.904861111111111in"}

**Figure 3a.** Trackline map for seismic profiles at the Tunica Mound
core sites. Core IDs are shown in this figure but line numbers are not,
because the line spacing is too close to legibly show all line numbers
in one page-size figure. Figures 3b and 3c show lines 1 through 7, and 8
through 14, respectively. Depth contours are in meters for this and all
following maps.

![](media/image4.png){width="7.0993055555555555in"
height="4.871527777777778in"}

**Figure 3b.** Trackline map for seismic profiles 1 through 7 at the
Tunica Mound core sites.

![](media/image5.png){width="7.095138888888889in"
height="4.884722222222222in"}

**Figure 3c.** Trackline map for seismic profiles 8 through 14 at the
Tunica Mound core sites.

![](media/image6.png){width="7.091666666666667in"
height="4.845833333333333in"}

**Figure 4.** Trackline map for seismic profiles at the Pigmy Basin core
site.

![](media/image7.png){width="7.088888888888889in"
height="4.965972222222222in"}

**Figure 5.** Trackline map for seismic profiles at the Bush Hill core
sites.

![](media/image8.png){width="7.095833333333333in"
height="4.959722222222222in"}

**Figure 6.** Trackline map for seismic profiles at the Kane Spur core
sites in the eastern Mississipi Canyon.

![](media/image9.png){width="7.0881944444444445in"
height="4.915972222222222in"}

**Figure 7.** Trackline map for seismic profiles at the West Mississippi
core sites.

![](media/image10.png){width="7.0875in" height="4.908333333333333in"}

Figure 8. Trackline map for seismic profiles at the Central Mississippi
core sites.