Metacarbonatite or marble? — the case of the carbonate, pyroxenite, calcite–apatite rock complex at Borra, Eastern Ghats, India


Le Bas, M.J., Subbarao, K.V. and Walsh, J.W. (2006) Metacarbonatite or marble? — the case of the carbonate, pyroxenite, calcite–apatite rock complex at Borra, Eastern Ghats, India. Journal of Asian Earth Sciences, 20, (2), 127-140. (doi:10.1016/S1367-9120(01)00030-X).

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Description/Abstract

Carbonatites are often of economic importance, which raises the problem of distinguishing carbonatites from limestones when either are metamorphosed to high-grade marbles. They can be of similar appearance, particularly those from the Proterozoic and Archaean of the Indian Subcontinent. This study also contributes to solving the problem of determining the frequency of alkaline and carbonatitic magmatism during the early history of the Earth.

The mineral assemblage of apatite–magnetite–phlogopite–calcite is common to marbles of both carbonatite and limestone origin. If pyrochlore is present that identifies the rock as carbonatite; if anorthite, fassaite, scapolite or spinel then it was formerly a limestone. If these minerals are absent, then trace element analysis can supply the critical Sr and REE data, which are both normally high in carbonatitic rocks and low in former limestones. These distinguishing factors are applied to the metamorphic carbonate, pyroxenite, calcite–apatite rock complex at Borra, Eastern Ghats, India, which has been variously interpreted as formerly a carbonatite and as a limestone. The evidence shows that the Borra rocks are meta-sedimentary.

Item Type: Article
Additional Information: Entered by Jane Conquer
ISSNs: 1367-9120 (print)
Related URLs:
Keywords: Carbonatite; Metacarbonatite; Marble; Pyroxenite; Trace elements; Al-pyroxene
Subjects: Q Science > QE Geology
Divisions: University Structure - Pre August 2011 > National Oceanography Centre (NERC)
Item ID: 58948
Date Deposited: 19 Aug 2008
Last Modified: 01 Jun 2011 09:42
Contributors: Le Bas, M.J. (Author)
Subbarao, K.V. (Author)
Walsh, J.W. (Author)
Date: December 2006
Additional Information: Entered by Jane Conquer
Status: Published
URI: http://eprints.soton.ac.uk/id/eprint/58948

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