Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach
The last glacial maximum, ca. 21,000 years ago, caused a fall in eustatic sea level of ca. 120 m below present. The low-gradient, shallow Sunda Shelf, Southeast Asia was subaerially exposed during this sea-level lowstand and experienced rising sea level thereafter. Sea level rose to a +1.3--5 m high...
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ftunivnorthcag:oai:libres.uncg.edu/43619 2024-02-11T10:08:04+01:00 Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach NC DOCKS at East Carolina University Twarog, Michael R. 2023 http://libres.uncg.edu/ir/ecu/f/0000-embargo-holder.txt English eng http://libres.uncg.edu/ir/ecu/f/0000-embargo-holder.txt sunda shelf;paleoenvironmental reconstruction;depositional environments 2023 ftunivnorthcag 2024-01-27T23:48:41Z The last glacial maximum, ca. 21,000 years ago, caused a fall in eustatic sea level of ca. 120 m below present. The low-gradient, shallow Sunda Shelf, Southeast Asia was subaerially exposed during this sea-level lowstand and experienced rising sea level thereafter. Sea level rose to a +1.3--5 m highstand ca. 6,500 cal yr BP, and then fell to modern sea level. The objective of this research is to characterize environmental change on the Sunda Shelf in response to the post-glacial rising eustatic sea level. To address this objective, six gravity cores were collected along a transect crossing the paleo-Chao Phraya incised river valley complex between peninsular Malaysia and southern Vietnam. Thirteen AMS radiocarbon samples, 130 bulk sediment magnetic susceptibility samples (BMS), 66 X-ray fluorescence spectrometry (XRF) samples, and 54 samples for the analysis of foraminiferal assemblages were used to characterize change in the depositional environments of the cored sediments. BMS, XRF, and foraminiferal analysis distinguish two main units. Unit 1 is found in the lower part of the cores and typically contains more terrestrial material than sediments further up-core as shown by higher BMS values, higher % Ti, % Al, % Fe, and lower indicators of marine influence, for example, lower % Ca, % planktonic foraminifera, and percentages of deeper water benthic foraminifera such as Heterolepa dutemplei. Unit 2 is characterized by a significant increase in % Ca, % Heterolepa dutemplei and % planktonic foraminifera ca. 6,500 cal yr BP. Unit 1 is consistent with shallower water depths and is part of a transgressive systems tract (TST, ca. 1 m thick) that terminates ca. 6,500 cal yr BP. Unit 2 represents the overlying highstand systems tract (HST, ca. 1 m thick) and is characterized by an increase in % planktonics, % Ca, and shifts in benthic foraminiferal assemblages, indicating deeper water conditions than the sediments below. This shift from a TST to a HST ca. 6500 cal yr BP is consistent with the Sunda Shelf sea-level ... Other/Unknown Material Planktonic foraminifera University of North Carolina: NC DOCKS (Digital Online Collection of Knowledge and Scholarship) Sunda ENVELOPE(-6.982,-6.982,62.205,62.205) |
institution |
Open Polar |
collection |
University of North Carolina: NC DOCKS (Digital Online Collection of Knowledge and Scholarship) |
op_collection_id |
ftunivnorthcag |
language |
English |
topic |
sunda shelf;paleoenvironmental reconstruction;depositional environments |
spellingShingle |
sunda shelf;paleoenvironmental reconstruction;depositional environments NC DOCKS at East Carolina University Twarog, Michael R. Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach |
topic_facet |
sunda shelf;paleoenvironmental reconstruction;depositional environments |
description |
The last glacial maximum, ca. 21,000 years ago, caused a fall in eustatic sea level of ca. 120 m below present. The low-gradient, shallow Sunda Shelf, Southeast Asia was subaerially exposed during this sea-level lowstand and experienced rising sea level thereafter. Sea level rose to a +1.3--5 m highstand ca. 6,500 cal yr BP, and then fell to modern sea level. The objective of this research is to characterize environmental change on the Sunda Shelf in response to the post-glacial rising eustatic sea level. To address this objective, six gravity cores were collected along a transect crossing the paleo-Chao Phraya incised river valley complex between peninsular Malaysia and southern Vietnam. Thirteen AMS radiocarbon samples, 130 bulk sediment magnetic susceptibility samples (BMS), 66 X-ray fluorescence spectrometry (XRF) samples, and 54 samples for the analysis of foraminiferal assemblages were used to characterize change in the depositional environments of the cored sediments. BMS, XRF, and foraminiferal analysis distinguish two main units. Unit 1 is found in the lower part of the cores and typically contains more terrestrial material than sediments further up-core as shown by higher BMS values, higher % Ti, % Al, % Fe, and lower indicators of marine influence, for example, lower % Ca, % planktonic foraminifera, and percentages of deeper water benthic foraminifera such as Heterolepa dutemplei. Unit 2 is characterized by a significant increase in % Ca, % Heterolepa dutemplei and % planktonic foraminifera ca. 6,500 cal yr BP. Unit 1 is consistent with shallower water depths and is part of a transgressive systems tract (TST, ca. 1 m thick) that terminates ca. 6,500 cal yr BP. Unit 2 represents the overlying highstand systems tract (HST, ca. 1 m thick) and is characterized by an increase in % planktonics, % Ca, and shifts in benthic foraminiferal assemblages, indicating deeper water conditions than the sediments below. This shift from a TST to a HST ca. 6500 cal yr BP is consistent with the Sunda Shelf sea-level ... |
author |
NC DOCKS at East Carolina University Twarog, Michael R. |
author_facet |
NC DOCKS at East Carolina University Twarog, Michael R. |
author_sort |
NC DOCKS at East Carolina University |
title |
Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach |
title_short |
Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach |
title_full |
Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach |
title_fullStr |
Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach |
title_full_unstemmed |
Holocene Paleoenvironmental Reconstruction of Depositional Environments on the Sunda Shelf, Southwest South China Sea, using a Multidisciplinary Approach |
title_sort |
holocene paleoenvironmental reconstruction of depositional environments on the sunda shelf, southwest south china sea, using a multidisciplinary approach |
publishDate |
2023 |
url |
http://libres.uncg.edu/ir/ecu/f/0000-embargo-holder.txt |
long_lat |
ENVELOPE(-6.982,-6.982,62.205,62.205) |
geographic |
Sunda |
geographic_facet |
Sunda |
genre |
Planktonic foraminifera |
genre_facet |
Planktonic foraminifera |
op_relation |
http://libres.uncg.edu/ir/ecu/f/0000-embargo-holder.txt |
_version_ |
1790607000232525824 |