Open AccessIndian summer monsoon and winter hydrographic variations over past millennia resolved by clay sedimentation
Author(s) -
Chauhan Onkar S.,
Dayal A. M.,
Basavaiah Nathani,
Kader U. Syed Abdul
Publication year - 2010
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2010gc003067
Subject(s) - chlorite , monsoon , geology , hydrography , oceanography , bay , precipitation , bengal , kaolinite , flux (metallurgy) , climatology , geochemistry , geography , paleontology , quartz , materials science , meteorology , metallurgy
Reconstruction of century‐scale Indian monsoon and winter hydrography is made from an AMS‐dated core located in the unique region of the southeast Arabian Sea which lies in the pathways of the low‐salinity Bay of Bengal Waters, advecting during winter northeast monsoon (NEM). Based upon clay mineral analyses in seawaters, we identify chlorite and kaolinite as specific clays supplied by the Bay of Bengal Waters and local fluvial flux (by the southwest monsoon (SWM) precipitation from the Peninsular India), respectively, along the southwest continental margin of India. An evaluation of clay flux and δ 18 O in G. ruber portrays century‐scale weaker SWM precipitation events during ∼450–650 yr, ∼1000 yr, and 1800–2200 cal yr BP. Kaolinite wt % and flux were found to be low during all these events, though chlorite had a persistent or enhanced flux. From the enhanced flux of chlorite and reduced kaolinite/chlorite ratio, during weaker phases of SWM, we deduce a stronger NEM (winter hydrography), implying an inverse coupling between the summer and the winter monsoon.