Himalayan Geology, Vol. 44 (1), 2023, pp. 130-146, Printed in India

Petrological studies of Bukdang Ophiolite, Shyok Suture Zone, Trans-Himalaya

IHSAN ULLAH LONE1, MEENAL MISHRA1, RAKESH CHANDRA2*

1School of Sciences, Indira Gandhi National Open University, New Delhi-110068, India

2Department of Geology, University of Ladakh, Leh, UT of Ladakh-194101, India

*Email (Corresponding author): rakeshchandra69@gmail.com

Abstract: The Bukdang Ophiolite represents the remnants of the Tethyan oceanic crust that closed as a consequence of subduction during the Late Cretaceous. This ophiolite is exposed in the northwestern part of the Shyok Suture Zone in and around Bukdang. In this paper, we present new field, petrographic and geochemical data from the Bukdang Ophiolite to understand its tectonic setting. Field observations attest to the presence of a majority of the components of a typical ophiolitic suite in Bukdang Ophiolite. These include layered gabbro, isotropic gabbro, gabbro norite, basalt, pillow basalt, plagiogranite, radiolarian chert and pelagic sediments. The imprints of metasomatism are observed in petrographic and geochemical data of mafics from the intrusive contact with the Ladakh Batholith. Geochemically, the mafics are characterized by calc-alkaline magma series varying in composition from basalt, basaltic-andesite, and andesite to dacite. They point to a genetic relationship and a common mantle melt origin. Statistical analysis based on dendrogram cluster analyses using the major oxides and CIPW norms, the rocks of Bukdang Ophiolite showed three distinct chemical types. The majority of the samples indicate an island arc tectonic setting and the geochemical variations were principally controlled by the fractionation of olivine, clinopyroxene and plagioclase. The low CaO/MgO (0.6 to 2.60) and intermediate FeO^(T)/MnO (71 to 200), values indicate the derivation of mafics from a pyroxenite mantle source.

Keywords : Shyok Suture Zone, Bukdang ophiolite, Ladakh, NW Himalaya