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Keser Singh ¹, V. C. Thakur ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Debra Dun 248 001, IN

Abstract

The microstructures associated with the crenulation cleavage in the slates of the Chamba Syncline, Western Himalaya, indicate that metamorphic differentiation following differential plastic flattening and fracturing is largely responsible for its origin. The stress gradient leads to migration of soluble minerals like quartz and calcite from limbs to hinge regions of microfolds as a result of pressure solution leaving behind micarich bands (insoluble) defining the crenulation cleavage.

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Keser Singh ¹, V. C. Thakur ¹

Affiliations
1 Wadia Institute of Himalayan Geology, General Mahadeo Singh Road, Dehradun, 248001, IN

Abstract

Samples of deformed pebbles in the slates from the Manjir Formation were collected from normal and inverted limbs of the Chamba Syncline. The axial ratios and orientation on two dimensional sections were determined from deformed quartz pebbles. The finite strain was calculated using Rf/φ technique. The two dimensional data were combined to give three dimensional finite strain and type of strain experienced by the pebbles at each locality. Regional variation in the strain distribution is represented by finite distortional strain (ε_s) for both normal and inverted limbs of the syncline. The results show that the deformation is of flattening type and the amount of strain increases from inner arc to outer arc of the Chamba Syncline. A total of about 28 per cent shortening has been noticed in the Manjir Formation.

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Keser Singh ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun, IN

Abstract

Strain reversal technique is applied to the pull-apart pyrite grains collected from the Chamba Formation of the Chamba Syncline. The computed ratio values of the extensional strain for X:Z section of the strain ellipsoid varies from 2.3 to 2.7 for the pyrite grains. The X direction of the strain ellipsoid coincides with the stretching lineation direction indicating minimum amount of strain values required for its development on the cleavage plane.

Keywords

Structures, Pyrite, Chamba Syncline, Himalaya.

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Keser Singh ¹, Rajesh Sharma ¹

Affiliations
1 Wadia Institute of Himalayan Geology, 33, General Mahadeo Singh Road, Dehra Dun-248 001, IN

Abstract

The study reports magnesite mineralisation along the Chamba Thrust. The Tethyan rocks occurring south of the Higher Himalaya have translated along the Chamba-Thrust over the Higher Himalayan Crystallines and the Chail Thrust Sheet. Localized occurrences of magnesite along the Chamba Thrust are from Jiuni of Brahmour and Bindrabani of the Pangi valley areas. The fluid inclusion studies of magnesite and dolomite, indicate that the fluid involved in the genesis of magnesite was hot saline in nature at about 200°C to 275°C. The magnesite is formed from the reaction of this fluid with the limestone/dolomite during thrusting.

Keywords

Economic Geology, Magnesite, Fluid Inclusions, Himachal Himalaya.

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