GEOLOGICAL CONDITIONS OF MIZORAM
Geologically the area is underlain by repetition of arenaceous and argillaceous sediments. The arenaceous and argillaceous group of rocks occurs in relatively higher and lower grounds respectively. These have deformed into a series of anticlinal and synclinal folds trending NNW-SSE to NNE-SSW with plunging direction is either towards north or south.
The state is occupied mainly by the rocks of the Tertiary formation ranging in age from Oligocene to Miocene to Recent. The general stratigraphic succession of the state is as follows:
AGE SERIES LITHOLOGY
RECENT Alluvium Clay, sands with pebbles conglomerate
and gravels.
---------------------------------------- Unconformity -------------------------------------------------
MIOCENE Tipam Sandstone medium to coarse grained,
ferruginous, friable with clay, shale
mottled.
Surma Bokabil Shale with siltstone, sandstone and
mudstone in alternation.
Bhuban Sandstone fine grained, compact,
Massive to well bedded with laminated
siltstone, shale
------------------------------------Unconformity -----------------------------------------------------
OLIGECENE Barail Shale, siltstone with sand of sandstone
fine grained.
Base not exposed
The Barails form the lower most rock units comprising siltstone and bands of soft and hard fine grained sandstone with strings of carbonaceous material. The Barail formation occurs in the north eastern part of the state mostly covering Champai district. The Surma is divided into two formations, Bhuban and Bokabil. The Bhuban is made up of grey sandstone and shale. Lower Bhuban is more arenaceous while the middle formation is more argillaceous and the Upper Bhuban is a combination of both and is soft in nature. The Bhuban formation occupies the major part of the state all along the length of the state. The Bokabil is predominantly argillaceous. The Bokabil formation mostly occurs along the western part of the state. The Tipam sandstone is of
