US EPA

6865241 

Journal Article 

Greenschist-facies sub-ophiolitic metamorphic rocks of Andaman Islands, Burma-Java subduction complex 

Pal, T; Bhattacharya, A; , 

2010 

Yes 

Journal of Asian Earth Sciences
ISSN: 1367-9120
EISSN: 1878-5786 

PERGAMON-ELSEVIER SCIENCE LTD 

OXFORD 

804-814 

10.1016/j.jseaes.2010.05.017 

WOS:000286571000027 

Sub-ophiolitic greenschist fades metamorphic rocks occur at the sole of ophiolite slices and as blocks in the melange zone beneath the Andaman ophiolite. These are represented by metabasics as actinolite schist to actinolite-chlorite schist and metasediments as garnetiferous quartzo-feldspathic mica-chlorite schist and piemontite quartzite to piemontite bearing quartz-muscovite-chlorite schist to muscovite-quartz-chlorite schist. Actinolite occurs along the schistosity and also as porphyroblasts. Syn to post-tectonic garnet shows no compositional zoning and represent almandine-spessartine solid solution (Alm(44-47), Sps(23-27), Gros(13-17). Pyr(9-10)). The metabasics are enriched in LILE and depleted in Zr and Y compared to N-MORB.The lithological features suggest that residual heat was the main heat source for greenschist-facies metamorphism. Top part of the subducting slab and overlying trench sediments were metamorphosed and dislocated by the close spaced thrusts in an accretionary prism setting. The field association indicates that metamorphism and the uplift of metamorphic rocks along with ophiolite slices were bracketed in between Cretaceous and Oligocene period. These processes were later than the Pre-Cretaceous emplacement of the ophiolites of Sumatra and Java. (C) 2010 Elsevier Ltd. All rights reserved.