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Das, Bhagwan
- On the Origin and Mechanics of Emplacement of Pegmatites and Related Bodies, Gurpa, Gaya District, Bihar
Authors
1 Department of Applied Geology, University of Saugar, Sagar (M. P.), IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 6 (1965), Pagination: 94-107Abstract
The origin of muscovite-pegmatites in the area around Gurpa, Gaya district, Bihar (India), seems to be associated with syn- to late-kinematic migmatization and granitization connected with Satpura Orogeny. They have been formed by a process of metasomatic replacement, with the proviso, that some may be replacement 'insitu' while others may probably be a 'mobilized replacement'. Various mechanisms of emplacement are indicated, non-displacement and non-mobility being the most significant. The pegmatitic constituents were introduced into the emplacement sites from outside; but local derivation by metamorphic differentiation is not ruled out for some of them.
- Nature of the Narmada-Son Lineament
Authors
1 Department of Applied Geology, University of Saugar, Sagar, Madhya Pradesh, IN
2 M.P. Ground Water Surveys, Irrigation Department, Madhya Pradesh, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 25, No 5 (1984), Pagination: 267-276Abstract
Critical examination of the several sections along the lineament from Handia to Barwaha have led to the identification of ten major and several minor faults in the area. They constitute a wrench system. The largest Badel-Dhasar-Ajnaskhurd fault is a primary first order right lateral wrench fault typically associated with the second order right-handed and the third order right lateral wrench faults. The Barjar-Bhadlipura fault is interpreted as a complementary first order left lateral wrench fault. The Badel-Dhasar-Ajnaskhurd and Barjar-Bhadlipura faults represent a first order set of conjugate shears. This would mean that the first order regional stress direction had WNW-ESE orientation. Folds related to the wrench faults have developed in the Precambrian rocks of the area. The most important Badel-Dhasar-Ajnaskhurd fault of the area around Chandgarh forms part of the Narmada-Son lineament. The Narmada-Son normal wrench fault steeply dipping towards south and Pachmarhi-JabaJpur normal fault dipping towards north constitute a graben structure.
The Narmada-Son lineament has existed since late Archaean and has got rejuvenated from time to time.