Statistical analysis of granophyric intergrowths in the Main Hill Arkasani Granophyre Pluton, eastern India |
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| Authors: | B Chattopadhyay |
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| Institution: | (1) Presidency College, Calcutta;(2) Present address: B-27, Govind Marg, 302 004 Adarsh Nagar, Jaipur, India |
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| Abstract: | The Main Hill Arkasani Granophyre Pluton (MAG), a product of Proterozoic intraplate acid magmatic activity, represents an anatectic melt of the enveloping rocks of dominantly pelitic composition with subordinate trondhjemitic gneiss and basic rocks. Petrography, chemistry, correlation between compositional attributes, areal variation of volume percent granophyric intergrowth, and varimax rotated factor analysis of compositional attributes of these rocks suggest that in the MAG pluton, plagioclase phenocrysts and biotite crystallized first, followed by change of level of emplacement of the magma when the groundmass started crystallizing at a rapid rate. The rapid growth of quartz and alkali feldspar crystallizing from the residual melt gave rise to the ubiquitous granophyric intergrowth in the late stage of crystallization. The alkali-rich residual liquid tended to concentrate toward the margin of the pluton where there is a profusion of granophyric intergrowths. |
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| Keywords: | petrography chemistry correlation areal variation factor analysis |
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