Download subsurface data at core sites

SUPPLEMENTARY MATERIAL TO Marcantonio et al “Particle sorting during sediment
redistribution processes and the effect on 230Th-normalized mass accumulation rates”
MV1014 SITE SURVEYS
Seismic reflection data shown here were collected on MV1014, on the R/V Melville.
MV1014 (Oct-Nov 2010), was carried out as part of an NSF-funded study to compare
geologically determined sediment focusing to geochemically estimated focusing factors. Seismic
lines in the Cocos Ridge survey were tied to ODP Site 1241 (Fig SM1; Leg 202 Shipboard
Scientific party, 2003a; Liao and Lyle, in press) and the Carnegie Ridge survey (Fig SM2) were
tied to ODP Site 1240 (Fig SM2). Multichannel lines were surveyed using a Scripps shipboard
geophysical group high-resolution seismic system. We deployed a source array of two 150 c.i.
GI seismic sources (45 c.i. generator, 105 c.i. injector) and recorded data from a 40-channel
Geometrics GeoEel seismic streamer with 12.5 m channel spacing, shot at a nominal underway
velocity of 6 knots. The digital data were recorded at 1ms sample rate for 7 seconds, with no
delay. Stacked and migrated data were then interpreted for seismic stratigraphy.
Transit seismic lines were recorded at both survey areas as the ship departed to the south after
coring the survey areas. These lines were recorded with the same 2-source GI array but with a
16-channel 12.5 m spacing Geo-Eel streamer while underway at a nominal speed of 8 knots. The
digital data were recorded at 1ms sample rate for 7 seconds, with no delay. The SEG-Y data and
images for both the MV1014 survey and the transit lines can be accessed through the UT
Academic Seismic Portal (http://www.ig.utexas.edu/sdc/).
Four coring sites, shown as yellow dots of Figure SM1, were also occupied within the Cocos
Ridge Survey (Cocos6N of Liao and Lyle, in press 2014) to sample sediment geochemistry.
Similarly, 4 coring sites were occupied within the Carnegie Ridge Survey but cores were only
recovered from 3 sites (Figure SM2). Cores designated MC are multicores, GC are gravity cores,
and JC are 10 cm piston cores. Cores were taken in order to track movement of 230Th and
measure mass accumulation rates.
SUBSURFACE DATA AT CORE SITES
Figures SM3 and SM4 show cores taken along Line 1A and Line 3, respectively, of the Cocos
Ridge Survey. The low amplitude upper section are sediments laid down from 5.9-0 Ma (Liao
and Lyle, in press), while the lower section is between 5.9 and 11.2 Ma. The first sediments
above basalt basement at Site 1241 is dated at 11.2 Ma (Leg 202 Shipboard scientific party,
2003a) . Core 1MC and 3JC (Fig SM3) are taken on a region that is essentially a hiatus, while
core 4JC is taken where Plio-Pleistocene sediments are slowly accumulating. In contrast, Cores
7MC and 8JC are taken where a very thick Plio-Pleistocene section was found.
The Carnegie Ridge Cores (Figures SM5, SM6, and SM7) were taken from a variety of
sedimentary environments. Cores 9MC, 10GC, and 11JC were taken in a depositional area near
the edge of the erosional Sand Dune Valley in the North Flank of Carnegie Ridge (Lonsdale and
Malfait, 1974). Sedimentation rates here are greater than every core collected at Cocos Ridge.
Core 11JC was collected in pelagic sediments on top of a slump section (Fig SM6). Cores 16MC
and 17JC were collected furthest north on an abyssal hill in the Panama Basin proper separated
from the Carnegie Ridge by an intervening abyssal valley. 16MC and 17JC have the highest
sedimentation rates, similar to those at Site 1240 Ma (Leg 202 Shipboard scientific party,
2003b). Sediments around 16MC and 17JC exhibit classic pelagic drape, with layers conforming
to topography.
REFERENCES
Leg 202 Shipboard Scientific Party, (2003a). Site 1241. In Mix, A.C., Tiedemann, R., Blum, P.,
et al., Proc. ODP, Init. Repts., 202: College Station, TX (Ocean Drilling Program), 1–101.
doi:10.2973/odp.proc.ir.202.112.2003.
Leg 202 Shipboard Scientific Party, (2003b). Site 1240. In Mix, A.C., Tiedemann, R., Blum, P.,
et al., Proc. ODP, Init. Repts., 202: College Station, TX (Ocean Drilling Program), 1–82.
doi:10.2973/odp.proc.ir.202.111.2003
Liao, Yuantao, and Mitchell Lyle (2014, in press) Late Miocene to Pleistocene sedimentation
and sediment focusing on the Cocos Ridge, eastern tropical Pacific Ocean. Marine
Geology
Lonsdale, P., and B. Malfait (1974), Abyssal dunes of foraminiferal sand on the Carnegie Ridge,
Geological Society of America Bulletin, 85, 1697-1712.
FIGURES
Figure SM1: Map of Cocos Ridge Survey (COCOS6N, Liao and Lyle, in press) showing seismic
lines (blue) and other tracklines (red). Cores are taken at yellow dots.
Figure SM2: Map of Carnegie Ridge Survey, showing seismic lines (blue) and other tracklines
(red). Cores are taken at yellow dots.
Figure SM3: Core sites 01MC, 03JC, and 04JC located along Cocos Ridge seismic line 1A.
Upper transparent layer are sediments with ages between 0-5.9 Ma.
Figure SM4: Core sites 06MC, 07MC, and 08JC located along Cocos Ridge seismic line 3.
Upper transparent layer are sediments with ages between 0-5.9 Ma.
Figure SM5: Carnegie Ridge core sites (09MC, 10GC, and 11JC) on Carnegie Ridge seismic line
7. Figure on the left shows the entire seismic line, while upper right is a detail of the
seismic line near the core site, and the bottom right is the 3.5 kHZ subbottom profiler.
Figure SM6: Carnegie Ridge core sites (12JC) on Carnegie Ridge seismic line 2. Figure on the
left shows the entire seismic line, while upper right is a detail of the seismic line near the
core site, and the bottom right is the 3.5 kHZ subbottom profiler. Core 12JC appears to be
taken on a slump that filled the small valley and which appears to have a thin layer of
pelagic sediment on top.
Figure SM7: Carnegie Ridge core sites (16MC, 17JC) on Carnegie Ridge seismic line 3. Figure
on the left shows the entire seismic line, while upper right is a detail of the seismic line
near the core site, and the bottom right is the 3.5 kHZ subbottom profiler. The valley to the
right in the full line marks the base of the Carnegie Ridge (Figure SM2).