Clay minerals as palaeomonsoon proxies: Evaluation and relevance to the late Quaternary records from SE Arabian Sea

Abstract

Palaeoclimatic studies are largely dependent on the quality of records and a prudent use of environmental proxy indicators. In this study, the factors affecting the detrital clay minerals in marine environment and their utility and reliability as palaeoclimatic proxies are evaluated and discussed. Systematic investigations using several sediment cores from the SE Arabian Sea reveal that despite the influence of several complicating factors, variations in clay mineral composition during the late Quaternary are essentially climate-dependant. Palaeoclimatic reconstruction based on clay mineral proxies suggests that the intensity of hydrolysis at source regions was relatively weak throughout the last glacial cycle and was minimum during the last glacial maximum (LGM). The early deglacial monsoon intensification started at approx. 16 ka B.P., which was further reduced during 12.5-11.5 ka B.P., synchronous with the global and regional climatic fluctuations. Maximum humidity was inferred between 9 and 6 ka B.P. and is comparable with similar records from this region. Regional correlations and consistency among various proxy indicators support the utility of clay minerals as a palaeoclimatic proxy.