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      https://www.ias.ac.in/article/fulltext/jess/130/0115

    • Keywords

       

      Southern Thar Desert margin; dune; aeolian activity; Indian Summer Monsoon; Inter Tropical Convergence Zone.

    • Abstract

       

      The present study summarizes the existing chronometric data of fossil dunes preserved in the southern Thar Desert margin (STM). The objective is to understand the episodes of dune accretion and causes of their spatial and temporal variability along the precipitation gradient. Based on the published ages, the study identifies three major phases of dune accretion. The oldest phase-I is dated between ${\sim}$ 25 and 17 ka (MIS-2); the second short-lived phase-II between ${\sim}$ 15 and 12 ka, whereas the phase-III occurred between 10 and 5 ka. The second phase terminates with the deposition of fluvially reworked aeolian sand which has the presence of microlithic artifacts and corresponds to the early Holocene strengthened Indian Summer Monsoon (ISM). The study suggests that during phase-I and II, the terrain witnessed a significant reduction in the ISM for which a more southerly position of the Inter-Tropical Convergence Zone (ITCZ) is implicated. During phase-III, an oscillating ISM with overall declining trend is attributed to mid-late Holocene minor fluctuations in the ITCZ (probably proximal to modern summer position). A conspicuous absence of dune building in the northern Thar Desert during the Last Glacial Maximum (LGM) is ascribed to the prevalence of hyper-arid conditions in comparison to the relatively moist conditions in the STM due to its proximity to the Arabian Sea. After ${\sim}$ 15 ka, both the STM and the Thar Desert show a broad synchroneity and that coincides with the gradual strengthening of the ISM.

    • Author Affiliations

       

      SHUBHRA SHARMA1 FALGUNI BHATTACHARYA2 GAURAV CHAUHAN3

      1. Department of Geography, Institute of Science, Banaras Hindu University, Varanasi 221 005, India.
      2. Institute of Seismological Research, Gandhinagar, Gujarat 382 009, India.
      3. Department of Earth and Environmental Science, K. S. K. V. Kachchh University, Bhuj 370 001, India.
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  • Journal of Earth System Science | News

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