Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

W. D. West ¹

Affiliations
1 Department of Applied Geology, University of Saugar, IN

Abstract

A study of the Deccan Trap flows around Sagar, Madhya Pradesh, has led to a consideration of the problem of the source of the flows, and of the distances to which individual flows may have travelled.

Assuming that the flows issued from fissures, now seen as dykes, it is difficult to account for the source of the flows that make up more than half the Deccan Trap outcrop where no dykes are found, unless it be assumed that the flows were capable of travelling long distances. In the limited area studied some of the flows have been followed for 40 to 80 miles without showing signs of thinning, and they may well have extended for very much further. It is possible, therefore, that the flows originated in those areas where dykes are found, namely in Cutch, Saurashtra, the N. Konkan, the Tapti and Narmada valleys, and the Gondwana basins of the Satpuras and further east, and that they travf'lled long distances to other parts of the outcrop.

Recent geodetic computations by E. A. Glennie support this view, and in particular suggest that the main source of the lavas was off the west coast of India north and south of Bombay, where remarkable gravity anomalies are found.

To have covered such large areas the flows must have been extremely fluid, and the possible causes of their fluidity are briefly considered.

Full Text

     

W. D. West ¹, V. D. Choubey ¹

Affiliations
1 Department of Applied Geology, University of Saugar, IN

Abstract

A study of the geomorphology of the country around Sagar and Katangi, M. P. has led to the conclusion that the present drainage, originating on a plateau of Deccan Trap lavas which once covered the whole area, has been superimposed on the underlying Vindhyan rocks. Around Sagar, with the partial removal of the Trap, a mature topography of hills and valleys carved out of horizontal Vindhyans has been resurrected. As a result the new drainage pattern bears little relation to this pre-Deccan Trap topography. The more powerful streams continued to erode in the courses they were following on the Deccan Trap, cutting gorges through Vindhyan hills; but the weaker streams appear to be adapting their courses to the old Vindhyan topography.

To the south-east of Sagar, along the south-eastern margin of the Vindhyan basin, the Vindhyan rocks have been considerably disturbed. A flat, elongated dome has been developed around Jabera, while further south-east sharp folding and faulting have produced long, steeply dipping ridges of Vindhyan, adjacent to the older Bijawar massif. Here also the Deccan Trap drainage is now seen superimposed on the Vindhyans, but there has also been a tendency to develop a radial drainage in the area of the dome, which has been carved into a basin.

The origin of typical Deccan Trap scenery, with its horizontal platforms and retreating scarp slopes, is discussed, as also the origin of the waterfall at Rahatgarh.

The time of uplift of the Vindhyan rocks, and the period of their folding and denudation in the Jabera-Katangi region, are also briefly alluded to.

Full Text

     

W. D. West ¹, R. S. Sharma ²

Affiliations
1 Department of Applied Geology, University of Sagar, Sagar, IN
2 Department of Geology, Banaras Hindu University Varanasi, IN

Abstract

The Sausar Group rocks (Precambrian) from the highest grade region contain wollastonite in the impure dolomitic marbles (Bichua Stage), but not in the isogradic Lohangi (Sub-stage) calcitic marbles which are characterised by the calcite-quartz association with or without diopside, grossularite and scapolite. The low-variance assemblage of grossularite-plagioclase-wollastonite-calcit ± quartz in the Bichua marbles, together with the muscovite-free sillimanite-biotite ± cordicrite paragenesis in the adjacent schists and their association with migmatites, suggest metamorphic temperatures ncar 650° C at about 3 kb pressure, inferred from geological and petrological evidence. The spatial distribution of the wollastonite-bearing assemblages and their occurrence with amphibole and vesuvianite in the Bichua-Stage marbles, unlike the Lohangi calc-silicate bands. provide evidence for lowering of XCO₂ by H₂O , F and Cl in the fluid phase which controlled the development of wollastonite in the investigated area.

Full Text

     

W. D. West ¹

Affiliations
1 Dept. of Applied Geology, H. S. Gaur Vishwavidyalaya, Sagar 470003, IN

Abstract

No Abstract.

Full Text

   

W. D. West

Abstract

No Abstract.

Full Text