Informatics Publishing Limited

M. K. Pandit ¹, L. S. Shikhawat ², V. P. Ferreira ³, A. N. Sial ³, S. K. Bohra ²

Affiliations
1 Department of Geology, University of Rajasthan, Jaipur 302004, IN
2 Geological Survey of India, Jhalana Dungri, Jaipur 302017, IN
3 NEG LABISE, Department of Geology, UFPE, C.P. 7852 Recife PE - 50.730-970, BR

Abstract

The pre-Malani basement, occurring to the southwest of the Malani Igneous Suite in western India is represented by an older, biotite trondhjemite (gneiss) and a younger, hornblende granodiorite. These granitoid assemblages (hitherto mentioned as unclassified granitoids) denote tectonically uplifted basement for the volcano-plutonic Malani magmatism. Biotite trondhjemite with well-developed gneissic fabric is significantly deformed as compared to hornblende granodiorite, which is slightly deformed. The basement granitoids exhibit a well-defined temporal and spatial relationship with each other, and are further intruded by Malani rhyolite/basic dykes. Well-preserved magmatic fabric of rhyolite/basic dykes suggests that the intrusive activity post-dated any deforrnational event. The geochemical signatures of the basement granitoids - moderate silica, high Sr, low FeO/MgO ratio and moderate alkali abundance, are quite distinct from the A-type geochemistry of Malani rhyolite dykes - high silica, high HFSE abundance, high FeO/MgO ratio and high alkali abundance, thus invoking different sources and emplacement history.

Keywords

Petrology, Malani Igneous Suite, Basement, Trondhjemite, Granodiorite, Western India.

Full Text

     

A. Maheshwari ¹, M. Coltorti ², A. N. Sial ³, G. Mariano ³

Affiliations
1 Department of Geology, University of Rajasthan, Jaipur-302 004, IN
2 Istituto di Mineralogia, Universita di Ferrara, IT
3 Department of Geology, UFPE, Recife, 50.732-970, BR

Abstract

The Malani volcanics of Gurapratap Singh and Din belong to a basalt-andesite -dacite-rhyolite association of Precambrian age. The preponderance of rhyolites over basic and intermediate rocks is a significant feature of the area. The rhyolities are characterised by chemical features, which indicate their A-type affinity. The study rules out their cogeneticity and suggests the crustal involvement in the genesis of Malani rhyolites.

Keywords

Petrology, Oxygen Isotopes, Malani Volcanics, Rajasthan.

Full Text

     

Anil Maheshwari ¹, A. N. Sial ², S. C. Mathur ³

Affiliations
1 Department of Geology, University of Rajasthan, Jaipur - 302 004, IN
2 NEG-LABISE, Department of Geology, C.P. 7852, Federal, University of Pernambuco, Recife, 50732-970, BR
3 Geology, J.N.V. University, Jodhpur, IN

Abstract

No Abstract.

Full Text