(Tripathi, 1986) and the uppermost Cretaceous intertrappean beds of Nagpur. (Gayet et al. ... and flora and taphonomy of the microvertebrate fauna. ... The inceptisols represent a stage in soil formation beyond that of .... A check list of the.
Palaeoenvironment of the Late Cretaceous MammalBearing Intertrappean Beds of N askal, Andhra Pradesh, India
G. V. R. PRASAD
AND
C. K
KHAJURIA
Reprinted from Memoir 37. Geological Society of India, pp. 337-362
GEOLOGICAL.
SOCIETY BAN GALORE 1996
OF
INDIA
MEMOIR GEOLOGICAL SOCIETY OF INDIA NO.3?, 1996, pp.33?-362
21 Palaeoenvironment of the Late Cretaceous MammalBearing Intertrappean Beds of Naskal, Andhra Pradesh, India G.V.R. PRASAD and C.K. KHAJURIA P. G. Department of Geology, University of Jammu, Jammu - 180 004, India. Abstract In this paper, an attempt is made to reconstruct the palaeoenvironment of the intertrappean beds of Naskal, Andhra Pradesh, by combining data from sedimentological features, habitats of the fauna and flora and mode of accumulation of the microvertebrate assemblage. The sedimentary history of the rocks shows that the intertrappean sediments were deposited in shallow, alkaline lakes, which were intermittently subjected to subaerial exposure causing the development of pedogenic features. Two distinct phases of pedogenesis, gleyed and inceptisol palaeosols in the lower portion and entisol and calcisol palaeosols in the upper portion, have been identified in the studied section. The overwhelming occurrence of freshwater lacustrine elements in the intertrappean fauna and flora also favour deposition in low lying, shallow, floodplain alkaline lakes distal in position from the sea-coast. The palaeocommunity structure of the intertrappean biota of Naskal is very different from that of Nagpur and Asifabad in having predominantly freshwater and terrestrial taxa and in the rare occurrence of marine elements. The taphonomic analysis of the Naskal microvertebrate assemblage discounts a scatological and fluvial origin of accumulation, and rather favours an attritional one. The assemblage had possibly resulted from the instantaneous death of the animals due to desiccation of lakes during drought conditions. This view is supported by surface features of the bones and also by sedimentary structures.
INTRODUCTION The Deccan Traps, one of the largest continental basalt provinces in the world, cover an area of 500,000 krn2 in peninsular India. These volcanic rocks are now considered to have erupted at the Cretaceous-Tertiary boundary within a short time span of 1 to 3 Ma (Courtillot et al. 1986, 1988; Duncan and Pyle, 1988; Saxena and Misra, 1995) and according to one viewpoint, this volcanic activity had caused the mass extinctions at the CretaceousTertiary boundary (Officer et al. 1987; McLean, 1985; Courtillot, 1990). Since the second half of 19th Century, the sedimentary strata underlying the lowermost ,:olcanic flows (=Lameta/infratrappean) and intercalating the 16
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