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Himalayan Geology, Vol. 30 (1), 2009, pp. 1-15 Printed in India
Response of 10 Ma thrusting event in the Himalayan Foreland sediments,
Kangra sub-basin, Himachal Pradesh, India
SUMIT K. GHOSH, SUBHAJIT SINHA# , ROHTASH KUMAR
Wadia Institute of Himalayan Geology, Dehradun - 248 001, India
#Present address: Department of Geology, DBS College, Dehradun-248001, India
Abstract: Using detrital modes and sedimentation pattern of Late Neogene
(11.3-5.5 Ma) coarsening up fluviatile succession of Himalayan foreland (Siwalik)
of the Kangra sub-basin, an attempt has been made to understand the
interrelationship of source area thrusting and their response in the
detrital modes. The sedimentary succession consists of dark grey sandstone
interbedded with purple mudstone in lower part, overlain by salt- and pepper
grey sandstone and variegated mudstone and capped by thickly bedded
conglomerate with minor amount of coarse - grained sandstone and mudstone.
The sedimentologic parameters show change in palaeochannel pattern from
meandering to braided streams at 10 Ma and inception of alluvial fan
settings at around 5.5 Ma. A remarkable variation in detrital modes is also
noticed between 10 and 9.0 Ma. The study suggests that prior to 10 Ma due to
tectonic activity along the Chail Thrust (CT) the depocenter received high
amount of Lesser- and Sub-Himalayan (LHZ and SHZ) footwall sedimentary and
metasedimentary fragments. Subsequently, after 10 Ma, the detritus from the
Chail Metamorphics Zone (CMZ) forming the hanging wall, became more
abundant. The present study infers that the variation in the drainage
pattern, sedimentation accumulation rate and detrital modes are collectively
pertinent to the 10 Ma tectonic activity of the Chail Thrust. |
