Timing of India‐Asia collision: Geological, biostratigraphic, and palaeomagnetic constraints

Abstract

[1] A range of ages have been proposed for the timing of India-Asia collision; the range to some extent reflects different definitions of collision and methods used to date it. In this paper we discuss three approaches that have been used to constrain the time of collision: the time of cessation of marine facies, the time of the first arrival of Asian detritus on the Indian plate, and the determination of the relative positions of India and Asia through time. In the Qumiba sedimentary section located south of the Yarlung Tsangpo suture in Tibet, a previous work has dated marine facies at middle to late Eocene, by far the youngest marine sediments recorded in the region. By contrast, our biostratigraphic data indicate the youngest marine facies preserved at this locality are 50.6-52.8 Ma, in broad agreement with the timing of cessation of marine facies elsewhere throughout the region. Double dating of detrital zircons from this formation, by U-Pb and fission track methods, indicates an Asian contribution to the rocks thus documenting the time of arrival of Asian material onto the Indian plate at this time and hence constraining the time of India-Asia collision. Our reconstruction of the positions of India and Asia by using a compilation of published palaeomagnetic data indicates initial contact between the continents in the early Eocene. We conclude the paper with a discussion on the viability of a recent assertion that collision between India and Asia could not have occurred prior to ∼35 Ma.

Petrogenesis of the early Eocene I-type granites in west Yingjiang (SW Yunnan) and its implication for the eastern extension of the Gangdese batholiths

“…In (b), the pink and gray fields note those from the Gangdese belt and the Northern magmatic belt ( 1987; Searle et al, 1987;Leech et al, 2005;Najman et al, 2010;Wang et al, 2011). In combination with other data from Klootwijk et al (1992), Hodges (2000), Najman et al (2005Najman et al ( , 2010 and Xu et al (2008), it is most likely that the India-Asia collision commenced at~50-55 Ma or later. Thus the dominant input of the juvenile mantle-derived magma should be genetically associated with a subduction rather than intra-crustal thickening setting.…”

“…Also shown in (a) are the data for granitoid rocks from the Gangdese belt (i.e., Debon et al, 1986;Harris et al, 1988b;Wen et al, 2008a;Huang et al, 2010) and from the Northern magmatic belt (i.e., Zhu et al, 2009b;Zhang et al, 2010b;Huang et al, 2012), and the Nianbo Formation of the Linzizong volcanic rocks in Tibet (i.e., Mo et al, 2008;Xie et al, 2011;Lee et al, 2012). In (b), the pink and gray fields note those from the Gangdese belt and the Northern magmatic belt ( 1987; Searle et al, 1987;Leech et al, 2005;Najman et al, 2010;Wang et al, 2011). In combination with other data from Klootwijk et al (1992), Hodges (2000), Najman et al (2005Najman et al ( , 2010 and Xu et al (2008), it is most likely that the India-Asia collision commenced at~50-55 Ma or later.…”

“…Searle et al, 1987;Klootwijk et al, 1992;Rowley, 1996;Hodges, 2000;Guillot et al, 2003;Leech et al, 2005;Najman et al, 2005;Garzanti, 2008;Xu et al, 2008;Najman et al, 2010;Wang et al, 2011;Sun et al, 2012); and (3) the Late Eocene (~34-42 Ma) (e.g., Aitchison and Davis, 2001;Aitchison et al, 2007Aitchison et al, , 2008Xia et al, 2009;Tan et al, 2010). To address some of the unresolved issues above, this paper presents a set of new zircon U-Pb geochronological, elemental and Sr-Nd-Hf isotopic data for the gneissic granite and leucogranite from the Nabang metamorphic zone in the Yingjiang area (West Yunnan, SW China).…”

Testing the effects of topography, geometry, and kinematics on modeled thermochronometer cooling ages in the eastern Bhutan Himalaya

“…50-55 Ma (e.g., Patriat and Achache, 1984;Klootwijk et al, 1992;Leech et al, 2005;Najman et al, 2010) and is divided into four geomorphic and tectonostratigraphic zones that span much of the east-west extent of the orogen. From south to north, these are the Subhimalaya, Lesser Himalaya, Greater Himalaya, and Tethyan Himalaya (Fig.…”

Early Eocene orthophragminids (Foraminifera) from the type-locality ofDiscocyclina ranikotensisDavies, 1927, Thal, NW Himalayas, Pakistan: insights into the orthophragminid palaeobiogeography

“…It is only upper Paleocene time slice for which we have adequate information to propose that orbitoidiform LBF replace the orthophragminids, which are lacking in Paleocene sediments in some sections in Salt Range and in Tibet (Ferrández-Cañadell, 2002;Zhang et al, 2013). LBF assemblages from the Paleocene and Eocene shallow-marine sediments have also been widely adopted to constrain the age of India-Asia collision by recording the transition from marine to continental facies and regional marine transgressions related to the tectonic phases along the passive margin of Indian Plate Beck et al, 1995;Gaetani et al, 1983;Green, Searle, Corfield, & Corfield, 2008;Najman et al, 2010;Rowley, 1996;Zhang, Willems, Ding, Grafe, & Appel, 2012;Zhu, Kidd, Rowley, Currie, & Shafique, 2005). However, interpretation of fossil data from different shallow-marine localities in Pakistan and Tibet is contradicting because of different approaches in evaluating the data in connection with the tectonic events.…”