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Fareedduddin ¹, A. K. Sharma ¹, U. Bose ¹

Affiliations
1 Geological Survey of India, Jhalana Dungari, Jaipur-302 004, IN

Abstract

The occurrence of tectonic slices of high-grade rocks in Pilwa-Chinwali-Arath area, about 25 km NNW of Ajmer is described. They occur in discontinuous strips Over a distance of 25 km within the Alwar metasediments of middle amphibolite facies. The high-grade sequence comprises charnockite-enderbite, two pyroxene granulite, pelitic granulite, leptynite, garnetiferous augen gneiss and garnetiferous amphibolite. Their tectonically-controlled occurrence and comparable mineral parageneses, the highgrade granulite facies rocks of the study area show striking similarity to those of Sandmata metamorphites emplaced in the Archaean Banded Gneissic Complex.

Keywords

Tectonic Slices, High-Grade Rocks, Granulite Facies, North-Central, Rajasthan, Delhi Fold Belt.

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Fareeduddin ¹, M. S. Reddy ¹, U. Bose ¹

Affiliations
1 Geological Survey of India, Jhalana Dungari, Jaipur-302004, IN

Abstract

The supracrustals occurring in the northern sector of the South Delhi Fold Belt (SDFB; main Delhi Synclinorium of Heron, 1953) between Ajmer-Pushkar valley and Sarnbhar Lake in north-central Rajasthan are classified into Anasagar migmatites and the overlying Ajmer Formation comprising Taragarh quartzites and Kalyanipura arkose-pelite-greywacke sequence. The Anasagar migmatites and paragneisses are intruded by Iatero genic granite(1600 Ma) and post orogenic ultramafic and alkaline rocks. Four folding and two shearing movements characterize these rocks. Three metamorphic zones could be identified in these supracrustals with grade increasing towards west: staurolite-kyanite grade (middle arnphibolite facies) in the eastern sector, sillimanite-muscovite grade (upper amphibolite facies) in the central sector, and orthopyroxene-plagioclase and orthopyroxene-sillimanite grade (granulite facies) in the western sector.

The Anasagar and Ajmer supracrustals are deposited in an Early Proterozoic ensialic basin in the Archaean BGC (Banded Gneissic Complex) protocontinent and differ from the other tectono-stratigraphic units of the SDFB in respect of lithological organisation, metamorphism and magmatism besides the latter being decisively of Upper Proterozoic age. The authors, therefore suggest a separate and older stratigraphic status to these supracrustals and delink from the rest of the SDFB stratigraphy.

Keywords

Stratigraphy, Delhi Supergroup, Ajmer, Sambhar, Rajasthan.

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U. Bose ¹, S. C. Nagal ², N. L. Sharma ², K. C. Prashra ², V. K. Sharma ², U. K. Bassi ²

Affiliations
1 4/193, SFS, Mansarovar, Jaipur - 302 020, IN
2 S.C.O. 98-100, Sector 17-C, Chandigarh-160 017, IN

Abstract

Pyroclastics are found in all the late Proterozoic clastic formations of the Outer Krol Belt in the Simla Himalaya. The field and petrographic characters leading to identification of the pyroclastics are described here.

Keywords

Petrology, Pyroclastics, Late Proterozoic, Simla Himalaya.

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