Contents lists available at ScienceDirect Journal of Asian Earth Sciences journal homepage: www.elsevier.com/locate/jseaes An Oligo-Miocene cricetid rodent from the Indus Group, NW Himalaya: Constraints on the age of initiation of continental sedimentation in the India–Asia collision zone Varun Parmar a, ⁎ , Supreem S. Jamwal b , Guntupalli V.R. Prasad c , Lobsang Palden a a Department of Geology, University of Jammu, Jammu 180006, India b Department of Geology, School of Science, Cluster University, Jammu 180001, India c Department of Geology, Centre for Advanced Studies, University of Delhi, Delhi 110007, India ARTICLE INFO Keywords: Indus Group Ladakh Himalaya India Cricetid rodent Oligo-Miocene ABSTRACT The Indus Tsangpo Suture Zone representing the zone of collision between Greater India and Asian mainland comprises a variety of rock sequences, among which, the youngest sedimentary succession, the Indus Group, represents the first continental sedimentation in the India–Asia collision zone, the age of which, has been a subject of debate since long. Here we report a cricetid rodent from the basal part of the Indus Group exposed in the Indus Suture Zone near Taruche village, Leh district, Ladakh Himalaya, India. The newly recovered rodent tooth shows a combination of archaic cricetid traits and possesses a mesolophid concurrently with protolophid II. Based on the dental grade of evolution of the new tooth, an Oligo-Miocene age is assigned to the basal part of the Indus Group. 1. Introduction The Cenozoic Era witnessed the India–Asia collision that led to slowing of northward drift of India, closing of the Neotethys Sea, and cessation of marine sedimentation in the collision zone. Hence geology and tectonic framework of the northwestern Himalaya have become a topic of active research as it leads to better understanding of major Cenozoic geological events in the collision zone. Though a general consensus places the initial timing of India–Asia collision around 55 ± 10 Ma (Powel and Conaghan, 1973; Le Fort, 1975; Molnar and Tapponnier, 1975; Patriat and Achache, 1984; Garzanti et al., 1987; Klootwijk et al., 1992; Beck et al., 1995; Rowley, 1996; Yin and Harrison, 2000; Wang et al., 2014; Zhuang et al., 2015; Hu et al., 2016, 2017 and references therein), the dating of this event has remained a subject of debate for long with estimates extending to as old as ~70 Ma and as young as ~25 Ma in some works (Yin and Harrison, 2000; Van Hinsbergen et al., 2012). This large variation in collision age is due to models suggesting collision of India with the intraoceanic island arcs and microcontinents prior to its final suturing with Asia (Van Hinsbergen et al., 2012; Bouilhol et al., 2013). Constraining the time of collision has remained a subject of prime interest for geoscientists. Consequently, extensive composite studies on Indus Tsangpo Suture Zone (ITSZ) rocks with respect to stratigraphic disposition, structure, sedimentology, paleontology and radiometric dating have been un- dertaken in the last three decades. ITSZ extends discontinuously over a distance of about 2500 km from Afghanistan in the west to Myanmar in the east in a NW–SE direction. It exposes a variety of rock sequences from deep sea sediments to flysch, ultrabasic and submarine volcanic rocks, plutonic intrusives and mo- lasse deposits. Much of the debate is over the nature of sedimentary rocks (flysch vs molasse) of the ITSZ (referred as Indus Basin Sedimentary Rocks (IBSR) in recent works viz., Henderson et al., 2010, 2011) and their age. The Cenozoic sequence of the ITSZ is divided into two groups, the older pre-syn-collision Tar Group and the younger post- collision Indus Group (Srikantia and Razdan, 1980; Garzanti and van Haver, 1988; Searle et al., 1990; Clift et al., 2002; Sinclair and Jaffey, 2001; Henderson et al., 2010). The Tar Group is a 1500 m thick, Middle Cretaceous to Early Eocene, mostly marine sequence, whereas the Indus Group is about 1200 m thick sedimentary sequence representing the depositional event immediately post-dating the collision of the Indian and the Asian plates. The Indus Group deposition is considered to have taken place in deltaic, alluvial fan, lake and riverine environments by most workers (Searle et al., 1990; Clift et al., 2001; Sinclair and Jaffey, 2001; Henderson et al., 2010), but in a relict sea in the form of an shallow embayment along the ITSZ that received sediments from rivers flowing from its north and south (Singh et al., 2015). The cessation of https://doi.org/10.1016/j.jseaes.2019.104190 Received 28 November 2018; Received in revised form 29 November 2019; Accepted 7 December 2019 ⁎ Corresponding author. E-mail address: varunparmarvp@gmail.com (V. Parmar). Journal of Asian Earth Sciences 190 (2020) 104190 Available online 09 December 2019 1367-9120/ © 2019 Elsevier Ltd. All rights reserved. T