Identification of aeolian loess deposits on the Indo-Gangetic Plain (India) and their significance

Abstract

Aeolian loess deposits contain abundant information about the evolution of the paleoenvironment. For example, paleoclimate changes recorded in Chinese loess area obtained significant achievement in the past few decades. Compared to Chinese loess, research on Indian loess is lacking. Currently, most studies focus on the Kashmir area located in the southern Himalayas, and studies on other areas are rare. However, field observations demonstrate that the sediments around the New Delhi-Agra-Jaipur Plain are similar to Chinese loess-paleosol sequences. For example, the boundary between two strata is transitional and without horizontal bedding. Moreover, obvious pedogenic horizons developed among sediment sequences, probably indicating unrecognised aeolian deposits in the Indo-Gangetic Plain (IGP). To confirm this, pilot samples were obtained from the IGP and detailed indoor measurements conducted. The results indicate that the distribution patterns of particle size and rare earth elements (REE) of the pilot samples are similar to Chinese loess. Furthermore, the scanning electronic microscopy (SEM) images of pilot samples show obvious conchoidal fractures, dash-shaped concavities, and abundant small pits that usually form through mechanical impact. These are typical characteristics of aeolian particles. In addition, environmental and rock magnetic measurements indicate that the dominant magnetic minerals in the pilot samples are magnetite and maghemite, and that they likely contain small amounts of hematite. Furthermore, conventional magnetic parameters are comparable with Chinese loess. Based on this, aeolian loess deposits are widely distributed in the IGP, which may have promoted the development of Indian farming and contributed towards the prosperity of ancient Indian civilisation. This study also provides a new and valuable record for the research on paleoclimate changes in the study area in the future.