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R. S. Chaudhri ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University, Chandigarh, IN

Abstract

No Abstract.

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R. S. Chaudhri ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University, Chandigarh, IN

Abstract

No Abstract.

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R. S. Chaudhri ¹, G. S. Gill ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University Chandigarh-160014, IN

Abstract

The megaclast representing boulder, cobble and pebble sized fragments was derived from the Tertiary formations exposed immediately northeast of Pinjaur along the course of the Koshallia River. The detritus did not travel far from the source rocks and was transported by southwesterly flowing currents. The megaclast was deposited in shallow turbulent water where it could acquire well sorted to moderately sorted character.

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R. S. Chaudhri ¹, G. T. S. Gill ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University, Chandigarh 160014, IN

Abstract

The heavy mineral assemblage of the Siwalik Group of Nepal Himalaya comprises non-opaque minerals like zircon, tourmaline, rutile, garnet, epidote (including zoisite and clinozoisite), staurolite, kyanile and sillimanite. The opaque minerals include ilmenite, magnetite, hematite and limonite. Staurolite serves as the marker mineral for the Lower Siwalik Formation, kyanite for the Middle Siwalik Formation and sillimanite for the Upper Siwalik Formation.

The over all heavy mineral assemblage and the mineralogical and textural properties of the various mineral species are suggestive of the derivation of a major part of the Siwalik sediments from metamorphic, acid and intermediate crystalline rocks.

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R. S. Chaudhri ¹, G. T. S. Gill ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University, Chandigarh 160014, IN

Abstract

Clay mineralogy of the Siwalik Group of Simla Hills was worked out by X-ray diffraction technique. The mineral assemblage comprises kaolinite, illite, chlorite, vermiculite, montmorillonite and mixed-layers. The source rocks bearing feldspars, micas and ferrornagnesian minerals suffered chemical decomposition and mechanical fragmentation in temperate climate. The sediments were deposited in rapidly subsiding fresh-water basins. Terrestrial and (or diagenetic origin has been assigned to the various clay minerals.

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R. S. Chaudhri ¹, G. T. S. Gill ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University, Chandigarh-160 014, IN

Abstract

The heavy mineral assemblage of modern sediments of the Ghaggar River comprises such nonopaque minerals like zircon, tourmaline, rutile, garnet, epidote, chloritoid/chlorite, biotite, staurolite, kyanite and sillimanite. Opaque minerals include ilmenite, magnetite, hematite and limonite. Percentage frequency of the various minerals in channel, levee and flood-plain microenvironments has been worked out. It is concluded that the distribution and size of the minerals are functions of the physical conditions prevailing in the microenvironments and the heavy mineral assemblage can safely be used to decipher the provenance and evironments of sedimentation of older deposits.

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R. S. Chaudhri ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University, Chandigarh, IN

Abstract

The paper discusses the rhythmic nature of the Paleocene-Eocene sequence of northwestern Himalayas. It is concluded that the Subathu Formation comprises the sediments accumulated in three sedimentary rhythms corresponding in close approximation to the Paleocene, Early Eocene and Middle Eocene Epochs. The cause of cyclic sedimentation is attributed to eustatic sea level changes accompanied by subsidence.

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R. S. Chaudhri ¹, G. D. Gupta ¹

Affiliations
1 Centre of Advanced Study in Geology, Panjab University, Chandigarh 160014, IN

Abstract

Nahan Phosphorite is classified into three types: fragmental phosphorite, pelletal phosphorite and nodular phosphorite. X-Ray Diffraction studies show that francolite (carbonate fluorapatite) constitutes the main phosphate mineral. It is concluded that the Nahan Phosphorite accumulated in shallow marine waters where euxinic conditions prevailed locally.

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