Clay Minerals and Micromorphology of the Loess Paleosols, Kashmir Valley, India

Abstract

Loess paleosols have been often studied to reconstruct late Quaternary past climate changes. In the present study, textural analysis, TOC, CaCO3 content, micromorphology and clay mineralogy of the three loess paleosol profiles from three sites (Choori, Alochibagh and Burzahama), from Kashmir valley are presented. Based on the dates of Burzahama section, the exposed loess paleosols are approximately dated to 45ka. Textural analyses suggest that the sediments are largely fine silt followed by silty loam and silty clay loam. The fine sand component in the loess and paleosols indicate that winds in the valley were strong, but in phases the wind velocity was low. The paleosols are much thicker than loess layers and form several horizons within the lithosections. The increase of CaCO3 content indicates that it has leached in phases and along with total organic carbon (TOC) resulted in mild pedogenesis with variations in the rate of pedogenesis within the paleosols and forming pedocomplexes. Micromorphology of the loess-paleosols indicates the presence of calcite nodules with iron oxide coating indicating sub-aerial weathering and pedogenesis. The presence of channel structures in loess paleosols formed due to root traces and pores probably during the warmer periods. The replacement of chlorite by smectite clays in loess paleosols suggests that the alteration of clay minerals probably took place in cold, dry, warmer climatic conditions in low wind regime.