Subduction zone characteristics of the Nidar Ophiolite Complex, Eastern Ladakh, India - Geochemical constraints

This study presents petrological and geochemical characteristics of various rock types from the Nidar ophiolite complex (NOC), eastern Ladakh, India, which include dunites, orthopyroxenites, clinopyroxenites, gabbros, basalts, an-desites, rhyolites, and minor plagiogranite. The aim of this study was to understand the geological processes which control the genesis, and tectonic affinity of the NOC, and its correlation with other nearby ophiolite complexes. The mafic to acidic NOC rock types are subalkaline in nature and shows affinity towards the spinel-lherzolite depleted mantle source, with partial melting degree of 5 to 30 %. The ultramafic cumulates display overall depleted patterns with respect to the primitive mantle and positive anomalies of large ion lithophile elements (LILE: Rb, Ba, K, Pb, and Sr) and negative anomalies of Nb, La, and Eu compared to other trace elements. However, gabbros, basalts, rhyolites, and plagiogranite show fractionated multi-element patterns with LILE enrichment and depletion of high-field strength elements (HFSE: Nb, P, and Ti). These geochemical characteristics in addition to high LILE to HFSE ratios such as La/Nb (> 1.4), Ba/Nb (2.36 -109.68), Rb/Nb (0.30 - 45.12), and La/Nb (1.06 - 3.99) indicate their origin from a depleted mantle source, which was metasomatized by fluids from the subducting slab. From the geochemical characteristics, it is concluded that the NOC evolved in a subduc-tion zone environment, similar to other Neo-Tethyan ophiolites such as the Nagaland-Manipur (India), Sabzevar (Iran), and Dras-Thasgam-Suru-Shergol (western Ladakh) ophiolites.

Automated summary

This study presents the petrological and geochemical characteristics of various rock types from the Nidar ophiolite complex in eastern Ladakh, India. The study concludes that the NOC evolved in a subduction zone environment similar to other Neo-Tethyan ophiolites.