Detrital Zircon Provenance Analysis in the Central Asian Orogenic Belt of Central and Southeastern Mongolia—A Palaeotectonic Model for the Mongolian Collage

Abstract

Our study is aimed at reconstructing the Palaeozoic–early Mesozoic plate tectonic development of the Central Asian Orogenic Belt in central and southeast Mongolia (Gobi). We use sandstone provenance signatures including laser ablation U-Pb ages of detrital zircons, their epsilon hafnium isotope signatures, and detrital framework grain analyses. We adopt a well-established terran subdivision of central and southeastern Mongolia. However, according to their affinity and tectonic assemblage we group them into three larger units consisting of continental basement, rift-passive continental margin and arc elements, respectively. These are in today’s coordinates: (i) in the north the late Cambrian collage from which the later Mongol-Okhotsk and the Central Mongolia-Erguna mountain ranges resulted, (ii) in the south a heterogeneous block from which the South Mongolia-Xin’gan and Inner Mongolia-Xilin belts developed, and (iii) in between we still distinguish the intra-oceanic volcanic arc of the Gurvansayhan terrane. We present a model for paleotectonic development for the period from Cambrian to Jurassic, which also integrates findings from the Central Asian Orogenic Belt in China and Russia. This mobilistic model implies an interplay of rift and drift processes, ocean formation, oceanic subduction, basin inversion, collision and suture formation in space and time. The final assemblage of the Central Asian Orogenic Belt occurred in Early Jurassic.

Age, petrogenesis, and tectonic implications of the late Permian magmatic rocks in the Middle Gobi volcanoplutonic Belt, Mongolia

“…325–314 Ma Adaatsag–Khukhu Davaa ophiolites (Tomurtogoo et al, 2005; Zhu et al, 2018) (Figures 1 and 2). The MOO opened in late Ordovician–early Silurian times, possibly as a back‐arc basin on the northern (in present coordinates) active margin of the Paleo‐Asian Ocean near the Central Mongolia–Erguna block (Bussien et al, 2011; Miao et al, 2020; Winkler et al, 2020).…”

“…Selenge Belt is believed to represent the northern, (Figure 1), and the Middle Gobi Belt is the southern active margin of the MOO (Parfenov et al, 2001; Zorin, 1999). The southern part of the Khangay–Khentey terrane experienced a back‐arc extension during the early Paleozoic (Bussien et al, 2011; Winkler et al, 2020), and from the Devonian and to early Carboniferous it evolved as a passive margin. In the late Carboniferous, the subduction re‐initiated resulting in the transportation of detrital zircons from volcanic rocks and plutons of the Middle Gobi Belt until the Triassic (Bussien et al, 2011; Kelty et al, 2008).…”