Major and trace element geochemistry of lake sediments, India: implications for weathering and climate control

Abstract

Climate plays an essential role in weathering of rocks, and a rich record of climatic change is preserved in rocks and sediments. The physical and chemical weathering also largely depend on climate prevailing in the area, apart from other factors. In an attempt to understand the dominance of physical over chemical weathering processes, the textural and geochemical studies of Wular Lake sediments from Jammu and Kashmir, northern India, have been taken up in the present study. These sediments documented several attentiongrabbing processes that operated during weathering, transportation, and deposition. Investigations have revealed that physical weathering dominated over chemical weathering, resulting in enhanced rates of erosion and consequent deposition of large detritus into the lake. Lake sediments and source rock chemistry are comparable, indicating low to moderate chemical weathering history of the source region which is consistent with cold regions and steep slope areas. Unusual enrichment of Cr values in sediments compared with source rocks signify a process of sediment-water interaction where Cr is removed from water and preferentially adsorbed onto clay fraction of sediments.

Petrography and geochemistry of the Lower Miocene Moghra sandstones, Qattara Depression, north Western Desert, Egypt

“…These chemical signatures are ultimately transferred to the sedimentary record, thus providing a useful tool for monitoring source‐area weathering conditions. Quantitative measures such as the CIA (Nesbitt & Young, ) and the PIA (Fedo et al, ) have been used in recent studies to interpret the degree of chemical weathering and to trace the source rock characteristics (e.g., Armstrong‐Altrin et al, ; Armstrong‐Altrin, Nagarajan, et al, ; Rashid, Gana, Masoodi, & Khan, ; Tawfik et al, ).…”

“…Quantitative measures such as the CIA (Nesbitt & Young, 1982) and the PIA (Fedo et al, 1995) have been used in recent studies to interpret the degree of chemical weathering and to trace the source rock characteristics (e.g., Armstrong-Altrin, Nagarajan, et al, 2015;Rashid, Gana, Masoodi, & Khan, 2015;Tawfik et al, 2017). (Fedo et al, 1995;Nesbitt & Young, 1982), whereas lower CIA values (i.e., 50-60) suggest incipient chemical weathering and reflect cold and/or arid conditions.…”

Recent Contributions in the Field of Sediment Geochemistry

“…These studies mainly used major elements, trace elements including REE, and radiogenic isotopes of Sr and Nd on sediments from different environments. Studies from the Kashmir valley of the Himalaya includes loess-paleosol and lake sediments by Ahmad and Chandra (2013) and Rashid et al (2015), respectively. Fluvial sediments from the upper Ganga River and its tributaries of the Garhwal Himalaya was studied by Singh (2010).…”

“…In the geochemical study of Wular Lake sediments from Jammu and Kashmir, northern India, Rashid et al (2015) attempted to understand the relative role of physical and chemical weathering processes. Their investigations have revealed the clay-silt dominant Wular Lake sediments were derived as a result of low to moderate chemical weathering in the source region.…”

“…Unlike the coarse-grained sediments, this phenomenon of natural homogenization of the finegrained sediments produces a better representative sample of the average composition of the provenance (McLennan et al, 1993;Weltje and Eynatten, 2004). Therefore, understanding the provenance lithology using the sediment geochemical composition has been a major research objective of many studies in India in the last few years (e.g., Ahmad and Chandra, 2013;Rashid et al, 2015;Singh, 2010;Tripathi et al, 2013).…”