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Authors
Affiliations
1 Department of Geology and Geophysics, IIT, Kharagpur, West Bengal - 721 302, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 52, No 4 (1998), Pagination: 457-462
Abstract
Armoured mud balls and till ball (sand ball) are reported for the first time from the Permocarboniferous Talchir Formation. The balls occur within a gullied part of the boulder bed. The balls found in the environment result from block breakage due to undercutting of a till face by meltwater stream and rolling during transportation. The unannoured spherical balls of diameter 3-14 cm composed of coarse materials are formed around tillite blocks and flat pebbles. whereas balls formed around clay or mud lumps are later armoured by grannule and pebble size clasts. The balls are termed till balls and mud balls respectively. Since the balls composed of coarse materials may also be derived from the environments other than glacial environments, it is appropriate to term these balls as sand ball.
Sand balls and mud balls along with associated primary structures may be used as palaeogeographic indicators. Presence of these balls and associated structures also reveal that though apparently the Boulder bed appear to be a single lithostratigraphic unit, in reality it is a complex of number of gravity flow deposits.
Keywords
Sedimentary Petrology, Talchir Gondwana, Sand Ball, Permo-Carboniferous, Orissa.
