Petrology and Geochemistry of Gabbros from the Andaman Ophiolite: Implications for their Petrogenesis and Tectonic Setting

The Andaman ophiolite has almost a complete preservation of ophiolite sequence with mantle section and comparatively less well-developed crustal section. The crustal part of the ophiolite comprises both ultramafic cumulates; dunite, wherlite and pyroxenite and mafic cumulates or gabbros. The gabbros are olivine gabbro, and pyroxene gabbro. They are distinguished into cumulates and non-cumulates. Geochemical features indicate that they are tholeiitic, fractionated and are formed in an arc-related tectonic setting. The large- ion lithophile (LIL) elements (Rb, Ba, Th, Sr) are relatively more enriched than Normal-mid-ocean ridge basalts (N-MORB). The enrichment of Large-ion lithophile (LIL) elements over the High-field strength (HFS) elements and the depletion of Nb relative to other High-field strength (HFS) - elements suggest involvement of subduction component in the depleted mantle source, and suggest that they are formed in a supra-subduction zone tectonic setting

[1]  R. Srivastava,et al.  High-Ti type N-MORB parentage of basalts from the south Andaman ophiolite suite, India , 2004 .

[2]  H. Staudigel.  3.15 – Hydrothermal Alteration Processes in the Oceanic Crust , 2003 .

[3]  P. Chakraborty,et al.  Geodynamic evolution of the outer-arc–forearc belt in the Andaman Islands, the central part of the Burma–Java subduction complex , 2003, Geological Magazine.

[4]  G. Jenner,et al.  Fe-Ti-enriched mafic rocks from South Andaman ophiolite suite: implication of late stage liquid immiscibility , 2001 .

[5]  D. Wyman,et al.  Trace element geochemistry of volcanic rocks : applications for massive sulphide exploration , 1996 .

[6]  J. Bédard.  Cumulate Recycling and Crustal Evolution in the Bay of Islands Ophiolite , 1991, The Journal of Geology.

[7]  A. Nicolas,et al.  Structures of Ophiolites and Dynamics of Oceanic Lithosphere , 1989 .

[8]  K. Ray,et al.  Chemical characters of volcanic rocks from Andaman ophiolite, India , 1988, Journal of the Geological Society.

[9]  D. Haldar.  Some aspects of the Andaman Ophiolite Complex , 1985 .

[10]  Y. Tatsumi,et al.  Origin of high magnesian andesites in the Setouchi volcanic belt, southwest Japan, I. Petrographical and chemical characteristics. , 1982 .

[11]  R. Pankhurst,et al.  The interpretation of igneous rocks , 1979 .

[12]  S. Humphris,et al.  Trace element mobility during hydrothermal alteration of oceanic basalts , 1978 .

[13]  J. Winchester,et al.  Geochemical magma type discrimination: application to altered and metamorphosed basic igneous rocks , 1976 .

[14]  A. Miyashiro,et al.  Tholeiitic and calc-alkalic series in relation to the behaviors of titanium, vanadium, chromium, and nickel , 1975 .

[15]  Julian A. Pearce,et al.  Tectonic setting of basic volcanic rocks determined using trace element analyses , 1973 .