Geochemistry and U–Pb zircon geochronology of the Jutogh Thrust sheet, Himachal Pradesh, NW‐Himalaya: Implications to the petrogenesis and regional tectonic setting

Abstract

We present datasets of the whole‐rock geochemistry and U–Pb zircon geochronology from the Jutogh Thrust (JT) sheet of eastern Himachal Pradesh, NW Himalaya, in order to explain the tectono‐magmatic environment in which they formed. The metapelite and granitoids of the JT sheet have moderate to high SiO2, Al2O3, Na2O, K2O, and rare earth elements (REE). The A/CNK (Al2O3/CaO + Na2O + K2O) ratio with magnitudes ≥1, indicates the peraluminous nature, calc‐alkaline series, and S‐type granitoids. The high values of Rb and Th as compared to Nb and the negative Ba anomaly also suggest the dominance of crustal source material. The distinct enrichment of large‐ion lithophile elements of Rb, Th, K, Ba and Pb and strong depletion in high‐field‐strength elements (HFSE) of Zr, Nb and Ti results in high incompatible elements/HFSE ratios, which suggest that the source is derived from many intra‐crustal tectonic environments. All samples are well‐fractionated REE patterns [(La/Yb)N = 6.06–17.37] and characterized by moderately flat enriched [(La/Sm)N = 2.31–4.71] of light rare earth elements. The negative Eu anomalies (Eu/Eu* = 0.18–0.71), suggest the plagioclase fractionation from the sourced magma and the origin of granitic gneiss through the high temperature (~800°C). The zircon U–Pb ages of granite range between 883.0 ± 15.0 Ma and 1260.0 ± 10.0 Ma, with a consistent peak of ~925.0 Ma. It confirms that the northern edge of the Indian Plate collided with an unnamed microcontinent. Also, in a contemporaneous process, the upper crust underwent partial melting, and the generated magma intruded in an extensional tectonic set‐up of the northern edge (i.e., presently known as the Jutogh and Vaikrita thrust sheets) of the Indian Plate during the Neoproterozoic. The available zircon U–Pb ages of the JT sheet range between 550–2750 Ma. The magmatic nature of zircons, with two peaks of ~825 Ma and ~910 Ma, suggests that episodic magmatic processes have taken place during the Neoproterozoic. This study revealed that the Higher Himalayan Crystalline Sequence was a meta‐sedimentary sequence and was deposited in an active margin set‐up of the northern edge of the Indian Plate.