SUBSURFACE QUATERNARY AEOLIAN STRATIGRAPHY IN THE GHAGGAR BASIN OF THAR-DESERT, INDIA

Quaternary sediments in the northern part of the Thar desert in India show fluvial, fluvio-lacustrine and aeolian lithe-successions, affecte d by episodic neotectonism. Near-surface Quaternary geological studies reveal three distinct generations of aeolian deposits. These are, (1) the youngest active aeolian dunes, (2) semistable pedogenized dunes o f post-Kalibangan cultural period (3000 to 2000 years B.C.) and, (3) c onsolidated older aeolian deposits (dating to c. 14 ka B.P.), and over lie gypcrete/calcrete and lacustrine deposits. Analyses of the deeper Quaternary formations in the area reveal that the Ghaggar sedimentatio n basin is much deeper than the surroundings, and hosts more than 350 m thick sediment infill. The basin is bound by distinctive boundary fa ults. Quaternary fluvial and fluvio-lacustrine deposits constitute the bulk of the total sedimentation package that shows a gradually increa sing thickness towards north and northeast. The northward deepening ba sin was aggraded with inflow of clastics from the south, either pari p assu, or in episodic pulses with neotectonic activities in the region. Two or three more aeolian sedimentation units which are older than th e exposed stable dunes, are also inferred within the stratigraphic col umn, suggesting phases of aridity during the mid-Pleistocene. (C) 1996 Academic Press Limited