Zircon U–Pb ages of Lohit Plutonic Complex, NE India: Constraints on episodic magmatism of eastern Trans‐Himalaya

Abstract

The Lohit Plutonic Complex (LPC) represents Trans-Himalayan magmatic rocks in the easternmost sector of the Himalayan Orogen. It is divided into leucogranite-granodiorite-diorite dominant suite in the NE and the gabbro-diorite-granodiorite-granite-trondhjemite suite in the SE by the Walong Thrust. U-Pb geochronological analyses of euhedral zircon grains from different magmatic phases of LPC reveal episodic magmatism. Zircon U-Pb age of 153.4 ± 1.4 Ma of a garnetiferous granite gneiss suggest that the crustal sourced magmatism was active in Arunachal Trans-Himalaya during the late Jurassic. U-Pb ages of subduction induced magmatic rocks of LPC range between 117 ± 0.6 Ma and 49.5 ± 0.3 Ma. A significant contribution in crustal recycling during the Oligocene-Miocene is evident from crustally derived leucogranites having U-Pb ages ranging from 35.6 ± 0.3 Ma to 30 ± 0.3 Ma. A comparison of the crystallization ages of the Western Trans-Himalayan units with those of eastern Trans-Himalayan units reveals an earlier onset of Tethyan arc magmatism in the eastern sector. The most prominent phase in the eastern sector is during the Late Cretaceous while western and central sector show major activity during the Palaeocene-Eocene.

Magnetic susceptibility, mineral chemistry, and geothermobarometry of granitoids from Lohit Plutonic Complex, Arunachal Trans‐Himalaya, Northeast India: Implications on emplacement and crystallization conditions of oxidized calc alkaline magmatic arc system

“…Haproff et al (2019) reported the Mesoproterozoic basement rocks (~1286 Ma) and Late Jurassic‐Cretaceous granitoids (~156–69 Ma), which are identical to those found in the Bomi‐Chayu complex of Lhasa terrane and northern Gangdese batholith, respectively. In a recent study, U–Pb zircon dating indicates two stages of magmatic activities, an early gabbro and diorite (~145 and ~107–90 Ma; Bikramaditya et al, 2020) and a late stage (~35–30 Ma; Pebam et al, 2022) post collisional, crust derived leucogranite in the LPC.…”

“…The LPC lies to the east of the eastern syntaxis in the eastern Arunachal Himalaya and is considered to as southeastern continuation of the Gangdese magmatic arc system of southern Tibet (Figure 1a). A number of studies on the geology, structure, geochemistry and geochronology of LPC rocks has been carried out (e.g., Bikramaditya et al, 2020; Goswami, 2011; Goswami, 2013a, 2013b, 2013c; Gururajan & Choudhuri, 2003; Haproff et al, 2019; Lin et al, 2013; Misra, 2009; Nandy, 1976; Pebam & Kamalakannan, 2019; Pebam et al, 2022). However, phase relationships, granite series assessment, and crystallization conditions of the LPC granitoids remain unknown.…”

Introduction, Part 2—Geodynamic evolution of Eastern Himalaya and Indo‐Myanmar orogenic belts: Advances through interdisciplinary studies

“…This Special Issue‐ Part 2 is a continuation of earlier Special Issue‐ Part 1 published in vol. 57 (2), of Geological Journal , which contained 26 research articles (Ao & Satyanarayanan, 2022; Baral et al, 2022; Bhowmik et al, 2022; Bora, Borah, et al, 2022; Bora, Mukherjee, et al, 2022; Deb & Ray, 2022; Devi & Singh, 2022; Devrani et al, 2022; Doley et al, 2022; Gogoi et al, 2022; Gupta et al, 2022; Hazarika & Kayal, 2021; Imtisunep et al, 2022; Liu et al, 2022; Luirei et al, 2022; Lukram & Tandon, 2022; Bidyananda et al, 2022; Majumdar, Gogoi, & Ghatak, 2022; Majumdar, Gogoi, Ghatak, Saikia, et al, 2022; Mukherjee et al, 2022; Pebam et al, 2021; Rashid et al, 2022; Saikia et al, 2022; Singh and Kshetrimayum, 2021; Singh, Guruaribam, Singh et al, 2022; Singh, Singh, Singh, et al, 2022; Srivastava, 2021; Srivastava & Kichu, 2021). Figure 2 displays the area of study of 29 papers included in this Special Issue 2.…”