(Table 1) Age determination of ODP Site 155-942

Glacioeustatic- and temperature-corrected planktonic foraminiferal oxygen isotope (dd18O) records from ODP Site 942 on the Amazon Fan provide a means of monitoring past changes in the outflow of the Amazon River. This study focuses on the last deglaciation and reveals that during this period there w...

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Bibliographic Details
Main Authors: Maslin, Mark, Ettwein, V J, Wilson, K E, Guilderson, Thomas P, Burns, Stephen J, Leng, Melanie J
Format: Dataset
Language:English
Published: PANGAEA 2011
Subjects:
155-942
Age
14C AMS
14C calibrated
dated
range
minimum
dated material
minimum/young
Calendar age
standard deviation
COMPCORE
Composite Core
DEPTH
sediment/rock
DSDP/ODP/IODP sample designation
Joides Resolution
Leg155
Ocean Drilling Program
ODP
Sample code/label
Sample ID
South Atlantic Ocean
Antarc*
Antarctic
Antarctica
Greenland
ice core
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.816306
https://doi.org/10.1594/PANGAEA.816306
Description
Summary:Glacioeustatic- and temperature-corrected planktonic foraminiferal oxygen isotope (dd18O) records from ODP Site 942 on the Amazon Fan provide a means of monitoring past changes in the outflow of the Amazon River. This study focuses on the last deglaciation and reveals that during this period there were significant variations in the outflow, which implies large changes in moisture availability in the Amazon Basin. Aridity in the Amazon Basin seems to occur between 20.5 ka (calendar) to 17.0 ka and 13.6 ka to 11 ka. The second arid period correlates with the start of the Antarctic Cold Reversal and aridity continues throughout the Younger Dryas period. We find that the large-scale trends in Amazon River outflow are dissimilar to high-latitude variability in either hemisphere. Instead high-resolution variations correlate with the d18O difference between Greenland and Antarctica ice core temperature records. This suggests a link between Hemispheric temperature gradients and moisture availability over the Amazon. Based on our results and previously published work we present a new testable 'dynamic boundary-monsoon intensity hypothesis', which suggests that tropical moisture is not a simple belt that moves north or south. Rather, the northern and southern boundaries of the South American Summer Monsoon (SASM) are independently dynamic and driven by temperature gradients within their individual hemispheres. The intensity of rainfall within the SASM, however, is driven by precessionally modulated insolation and the resultant convection strength. Combining these two influences produces the dynamic heterogenic changes in the moisture availability observed over tropical South America since the Last Glacial Maximum.

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