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Paired measurements of foraminiferal delta 18 O and Mg/Ca ratios of Indian monsoons reconstructed from Holocene to Last Glacial record

DRS at CSIR-National Institute of Oceanography

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Title Paired measurements of foraminiferal delta 18 O and Mg/Ca ratios of Indian monsoons reconstructed from Holocene to Last Glacial record
 
Creator Mahesh, B.
Banakar, V.K.
Burr, G.
 
Subject monssons
palaeoclimate
foraminifera
oxygen isotope dating
Holocene
Globigerinoides sacculifer
 
Description The effect of seasonally reversing monsoons in the northern Indian Ocean is to impart significant changes in surface salinity (SS). Here, we report SS changes during the last 32 kyr in the Lakshadweep Sea (southeastern Arabian Sea) estimated from paired measurements of delta sup(18)O and sea surface temperature (SST) using Globigerinoides sacculifer, an upper mixed layer dwelling foraminifera. The heaviest delta sup(18)O G. sacculifer (-0.07 + or -0.08 ppt) is recorded between 23 and 15 ka, which could be defined as the last glacial maximum (LGM). The delta sup(18) G. sacculifer shift between the LGM and Holocene is 2.07 ppt. The SST shows an overall warming of 2 degrees C from the LGM to Holocene (28 degrees C to 30 degrees C). However, coldest SSTs are observed prior to LGM, i.e., approx. 27 ka. The SS was higher (approx. 38 psu) throughout most of the recorded last glacial period (32.5 - 15 ka). This high salinity together with generally lower SSTs suggests a period of sustained weaker summer or stronger winter monsoons. The deglacial warming is associated with rapid reorganization of monsoons and is reflected in decreased salinity to a modern level of approx. 36.5 psu, within a period of approx. 5 kyr. This indicates intensification of summer monsoons during cold to warm climate transition.
 
Date 2011-11-14T10:51:04Z
2011-11-14T10:51:04Z
2011
 
Type Journal Article
 
Identifier Acta Geologica Sinica, vol.85; 2011; 950-956
http://drs.nio.org/drs/handle/2264/3955
 
Language en
 
Rights An edited version of this paper was published by Springer/Geological Society of China. This paper is for R & D purpose and Copyright [2011] Springer.
 
Publisher Geological Society of China