Pyroxene-sövite in Amba Dongar carbonatite-alkalic complex, Gujarat
| Autor: | Shrinivas G. Viladkar |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Calcite
Zirconolite Sovite 010504 meteorology & atmospheric sciences Geochemistry Geology Pyroxene engineering.material 010502 geochemistry & geophysics 01 natural sciences chemistry.chemical_compound chemistry Magma Carbonatite engineering Phlogopite 0105 earth and related environmental sciences Magnetite |
| Zdroj: | Journal of the Geological Society of India. 90:591-594 |
| ISSN: | 0974-6889 0016-7622 |
| DOI: | 10.1007/s12594-017-0756-y |
| Popis: | The present paper for the first times gives details of pyroxenesovites of Amba Dongar and discusses significance of these pyroxenes in evolution of carbonatite magma in Amba Dongar. Calciocarbonatite (sovite) forms the major mass of carbonatite in Amba Dongar complex. It shows large variation in texture and mineral composition and has complex evolutionary history. Three types of compositional variations are observed in sovite samples, (1) monomineralic sovites are coarse grained with 99% calcite, (2) sovites with abundant apatite, barite, pyrochlore, magnetite and zirconolite and (3) silico-sovite with of clinopyroxene and phlogopite. In the crystallization history of various sovite types, silico-sovite seems to have crystallized as an earlier phase and was later caught up in major sovite mass. Both, phlogopite-sovite and pyroxene-sovite are coarse grained and exhibit hypidiomorphic texture. Phlogopite is strongly zoned with Mg-rich core to Fe-rich rims. Pyroxenes also exhibit zoning with decrease in Ca and Mg and increase in Fe and Na from core to rim. In general composition of clinopyroxene varies from diopsidic to aegirine-augite. Pyroxenesovites show good concentration of Ba, Sr, Nb and LREE. Elevated concentrations of LREE are found in two aegirine-sovites. |
| Databáze: | OpenAIRE |
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