Istituto di Geoscienze e Georisorse     
Spencer D., Tonarini S., Pognante U. Geochemical and Sr-Nd isotopic characterisation of Higher Himalayan eclogites (and associated metabasites). In: European Journal of Mineralogy, vol. 7 (1) pp. 89 - 102. Schweizerbart, 1995.
Eclogites of the Higher Himalaya were analysed for their bulk rock geochemistry and Sr-Nd isotopic composition. These results are compared to lower grade metamorphic equivalents of rocks of the same age as well as to unmetamorphosed basalt. Major and trace element diagrams indicate tholeiitic to alkalic magma compositions which evolved by fractional crystallisation. ⁸⁷Sr/⁸⁶Sr initial values for the eclogite are 0.7053-0.7073 with values increasing for metabasites of lower metamorphic grade. ¹⁴⁷Sm/¹⁴⁴Nd values range from lower than chondritic to slightly higher. ¹⁴³Nd/¹⁴⁴Nd measured values range from 0.51201 to 0.51283, with ɛ_(Nd(t)) from +4.9 to -10. The lowest values occur in the least metamorphosed rocks. Based on their bulk geochemistry and isotope data, the eclogites could be the equivalents of the Permian Panjal Traps. The observed isotopic "trends" are here suggested not to be explained by variations of metamorphic grade, but indicate some protolith contamination with the evolved Higher Himalayan continental crust.
URL: http://www.schweizerbart.de/j/ejm/
Subject eclogite
high-pressure metamorphism
Sr-Nd systematics
Panjal Traps

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