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The record of Late Pleistocene biogenic sedimentation in the eastern tropical Pacific Ocean

The record of Late Pleistocene biogenic sedimentation in the eastern tropical Pacific Ocean We have generated ∼300 Kyr records of biogenic opal, calcite, and organic carbon (Corg) for three cores in the eastern and central equatorial Pacific Ocean and have compared the records to determine whether common periods of biogenic sedimentation have occurred throughout the region. We find that Corg has been deposited in common pulses throughout the area, while opal has a much more local pattern of variation. Calcite varies regionally, but the record is shaped by superimposed dissolution and productivity processes. The most intense Corg peak occurs at 18 ka and can have greater than 2 times the Holocene Corg content. Other major Corg peaks occur 150 ka and perhaps at 280 ka. We have compared the Corg record in one of the cores, V19–28, to a model deepwater oxygen record developed from ∂13C data in the nearby V19–30 to test whether the Corg record has been mostly shaped by degradation or by the rain of organic matter from the euphotic zone. We found no coherence between the two records, implying that the Corg record is primarily a measure of productivity. By comparing the opal, calcite, and Corg records in V19–28, a core which is at or above the lysocline, we found that both increased calcite and opal deposition matches high Corg accumulation. We also found, however, that the calcite and opal records were uncorrelated, so that episodes of high opal deposition do not necessarily accumulate calcite rapidly. We hypothesize that at least two different plankton communities have been dominant in the waters above this site, one rich in opal‐secreting plankton and one more dominated by calcite producers. The opal‐rich plankton community was dominant during the intervals 10–15 ka and 35–60 ka. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Paleoceanography and Paleoclimatology Wiley

The record of Late Pleistocene biogenic sedimentation in the eastern tropical Pacific Ocean

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References (46)

Publisher
Wiley
Copyright
Copyright © 1988 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0883-8305
eISSN
2572-4525
DOI
10.1029/PA003i001p00039
Publisher site
See Article on Publisher Site

Abstract

We have generated ∼300 Kyr records of biogenic opal, calcite, and organic carbon (Corg) for three cores in the eastern and central equatorial Pacific Ocean and have compared the records to determine whether common periods of biogenic sedimentation have occurred throughout the region. We find that Corg has been deposited in common pulses throughout the area, while opal has a much more local pattern of variation. Calcite varies regionally, but the record is shaped by superimposed dissolution and productivity processes. The most intense Corg peak occurs at 18 ka and can have greater than 2 times the Holocene Corg content. Other major Corg peaks occur 150 ka and perhaps at 280 ka. We have compared the Corg record in one of the cores, V19–28, to a model deepwater oxygen record developed from ∂13C data in the nearby V19–30 to test whether the Corg record has been mostly shaped by degradation or by the rain of organic matter from the euphotic zone. We found no coherence between the two records, implying that the Corg record is primarily a measure of productivity. By comparing the opal, calcite, and Corg records in V19–28, a core which is at or above the lysocline, we found that both increased calcite and opal deposition matches high Corg accumulation. We also found, however, that the calcite and opal records were uncorrelated, so that episodes of high opal deposition do not necessarily accumulate calcite rapidly. We hypothesize that at least two different plankton communities have been dominant in the waters above this site, one rich in opal‐secreting plankton and one more dominated by calcite producers. The opal‐rich plankton community was dominant during the intervals 10–15 ka and 35–60 ka.

Journal

Paleoceanography and PaleoclimatologyWiley

Published: Feb 1, 1988

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