Complete preservation of ophiolite suite from south Andaman, India: A mineralchemical perspective

Journal of Earth system science

Abhishek Saha1¹  David Moecher2²  Suvankar Chakraborty2²  Avik Dhang1¹  Jyotisankar Ray1¹ 

[1] Department of Geology, University of Calcutta, 35, Ballygunge Circular Road, Kolkata 700 019, India.$$;Department of Earth and Enviornmental Sciences, University of Kentucky, Lexington, Kentucky 40506, USA.$$

关键词: South Andaman;    serpentinite;    geothermobarometry;    zoned plagioclase;    idealized ophiolite.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Field studies supplemented by petrographic analyses clearly reveal complete preservation of ophiolite suite from Port Blair (11° 39′ N: 92° 45′E) to Chiriyatapu (11° 30′ 24′′N: 92° 42′ 30′′E) stretch of South Andaman. The ophiolite suite reveals serpentinite at the base which is overlain unconformably by cumulate ultramafic–mafic members with discernible cumulus texture and igneous layering. Basaltic dykes are found to cut across the cumulate ultramafic–mafic members. The succession is capped by well exposed pillow basalts interlayered with arkosic sediments. Olivine from the basal serpentinite unit are highly magnesian (Fo80.1–86.2). All clinopyroxene analyses from cumulate pyroxenite, cumulate gabbro and basaltic dyke are discriminated to be `Quad’ and are uniformly restricted to the diopside field. Composition of plagioclase in different lithomembers is systematically varying from calcic to sodic endmembers progressively from cumulate pyroxenite to pillow basalt through cumulate gabbro and basaltic dyke. Plagioclase phenocrysts from basaltic dyke are found to be distinctly zoned (An60.7–An35.5) whereas groundmass plagioclase are relatively sodic (An33–An23.5). Deduced thermobarometric data from different lithomembers clearly correspond to the observed preservation of complete ophiolite suite.

【 授权许可】

Unknown