IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002
phenomenon of regional stress pattern. The NW and NE
trending faults, which are pre-existing in the basement, are also
reflected in the Gondwana sediments perhaps due to the
reactivation of basement faults. The other trends that are
confined to the Gondwana formation can be related to the
normal faulting of post-Gondwana deformation.
9, CONCLUSIONS
The Precambrian formation is predominantly occupied by NW-
SE grain and NE-SW shear fractures and EW faults. The
Sullavai and Pakhal formations are prominently occupied by
NW-SE structural grain and EW faults.
The Talchir formation is predominantly dominated by EW
faults while the Barakar prominently shows NNE-SSW and
EW fracture system. The Barren measure is predominantly
occupied by NNE and NW followed by EW fracture system.
The EW set of fractures appears to be oldest which might have
got reactivated during lower Gondwana period as a gradual
increase in the number of these features trending in EW
direction is observed in Precambrian, Sullavai and Pakhal, and
lower Gondwana formation, viz., Talchir, Barakar and a
maximum extent in Barren measures. The NS compression
appears to be of Maleri period due to which the Kamthi and
Maleri are showing conjugate pair of shear fractures in NE
(N35°-45°E) and NW (N25°-45°W) directions and NS tensional
fractures.
The predominant occurrence of NS tensional fractures in
Gollapalli sandstones and its absence in subsequent formations
(Raghavapuram shales, Tirupati sandstones, Trap, and
Rajahmundry sandstones) are of contemporary to Maleri
formation as similar trends are seen in Maleri formation also.
The Kota formation has undergone NNE fracturing which may
be due to local disturbances, as the fracturing in this direction is
not predominantly seen in lower or upper Gondwana
formations. The coastal Gondwanas have undergone
predominantly NW-SE (N45°-55°W) shear fractures, which is
due to reactivation of basement faults. The Raghavapuram
shale and Tirupati sandstone are not contemporary to Kota or
Chikiala formations respectively and appears to be post-
Chikiala and pre-Cretaceous as the fracturing pattern is totally
different.
The N45°-55° E fracturing is reactivated during teritiary period,
which has resulted in predominant fracture development in this
direction in Rajahmundry sandstones and Trap. The ENE
fracturing observed in the Alluvium may be due to neo-
tectonism as predominance of this direction is not observed in
other formations.
ACKNOWLEDGEMENTS
We gratefully acknowledge the Singareni Colleries Company
Limited (SCCL), Kothagudem for sponsoring this project.
Grateful thanks are due to Sri.B.V.Ramana Murty, Sri.Saibabu
Rao, Sri.Jaganmohan of SCCL, Dr.T.R.K.Chetty of NGRI and
Dr.P.V.L.P.Babu of ONGC for actively participating in the
technical discussions.
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