Depositional history and palaeoclimatic variations at the northeastern fringe of Thar Desert, Haryana plains, India

• Published in: Quaternary international 2012-02, Vol.250, p.37-48
• Main Authors: Saini, H.S., Mujtaba, S.A.I.
• Format: Article
• Language: English
• Subjects: alluvium; Aridity; climate; dry environmental conditions; luminescence; monsoon season; rivers; sand; stratigraphy; tectonics
• ISSN: 1040-6182; 1873-4553
• DOI: 10.1016/j.quaint.2011.06.002

The >400 m thick column of alluvial, lacustrine and aeolian strata at the semi-arid northeastern fringe of Thar Desert in Haryana has vast potential to provide information on fluctuating climate since the Middle Pleistocene. The sediment column has been deposited by Himalayan-fed rivers, most of which subsequently disappeared due to climatic and tectonic reasons. The distinctive lithologies with minor variations offer direct evidence to their depositional environments and indirect clues to the monsoonal climate of the region. In this study, broad palaeoclimatic variations, since the terminal part of the last interstade, have been inferred on the basis of sediment characters and luminescence dating of representative sections along the Thar margin and in its ameliorated part. The general field stratigraphy established for the upper part of Late Quaternary plains comprises a buried alluvial sequence of grey micaceous sand, deposited by perennial rivers, overlain by undifferentiated, partially buried aeolian brown sands. Optically stimulated luminescence (OSL) ages from the upper parts of alluvium indicate a gradual disorganization of the river system ca. 28–20 ka. The disorganization commencing at around 28 ka corresponds with the increasing aridity of the last glacial maximum (LGM) and shows the decreasing strength of the monsoon. However, the survival of river system until ca. 20 ka, even during the LGM aridity, signifies that the monsoon had not completely disappeared in this region. Further weakening of monsoon is indicated by the deposition of aeolian sand over the alluvium. The area witnessed a major phase of aeolian deposition ca. 18–12 ka which extended up to the present day 600 mm isohyet. The subsidiary phase appears to have prevailed in southern parts of Haryana ca. 9–7 ka. Younger aeolian activity has occurred since ca. 3.2 ka near the Thar front. No record of aeolian deposition during LGM is identified in this area, as in the core of the Thar Desert. However, the post LGM, aeolian deposition in Haryana is found to have begun earlier and continued longer than in the Thar Desert.