Paleoclimatic variations from Lacustrine Sediments of Chikkamagalur District Karnataka using Multiple Proxies

Abstract

Rainfall and temperature being important components of climate have a great newlineinfluence on terrestrial life. The Earth s climate has undergone several changes ever since newlineits origin 4.5 billion years ago. Extreme climatic events like floods and droughts, newlineresulting from human-induced climate change, have already been reported from many newlineparts of the world. Hence, quantification of past monsoonal changes is important in terms newlineof the changing climatic scenario. It is important to study abrupt climate change, as well newlineas changes in the frequency and intensity of past climate to enable the society to prepare newlinefor potential future climate change and to assess the impact of anthropogenic activities on newlineclimate. newlineScientists have used a variety of archives and proxies to determine these past newlineclimatic changes. In this study, the archive of lacustrine sediments has been used to newlinedetermine paleoclimate using multiple proxies. Several studies have attempted to estimate newlinerainfall using magnetic susceptibility as a proxy. However, the focus has primarily been newlineon lakes from temperate regions (Foster et al. 2008; Zhang et al. 2012; Shen et al. 2008); newlineonly limited studies have been carried out in tropical regions. newlineShankar et al. (2006) proposed magnetic susceptibility as a proxy for rainfall in newlineThimmannanayakanakere area in tropical southern India (average annual rainfall = 638 newlinemm) based on the positive correlation between magnetic susceptibility of newlineThimmannanayakanakere sediments and rainfall. Sandeep et al. (2015) confirmed that newlinemagnetic susceptibility may be used as a rainfall proxy in tropical regions with high newlinerainfall (4200 mm/year). In this study, the environmental magnetic properties of a newlinesediment core from Hirekolale Lake from tropical southern India were investigated to test newlineShankar et al. s (2006) proposition in a tropical area with medium rainfall (1925 newlinemm/year). Other techniques used in this study to support the inference from rock newlinevii newlinemagnetic investigations are citrate-bicarbonate-dithionite (CBD) treatment, inorganic newlinegeochem