Petrogenesis of post-collisional magmatism at the Carboniferous–Permian boundary in central Inner Mongolia, NE China: insights into when the Hegenshan Ocean closed?

Petrogenesis of Early Permian Intrusive Rocks from Southeastern Inner Mongolia, China: Constraints on the Tectonic Framework of the Southeastern Central Asian Orogenic Belt

“…7). This characteristic is significantly different from that of the bimodal magmatic rocks from East-Ujimqin (Cheng et al, 2014) or West-Ujimqin (Zhang et al, 2008;Zhang et al, 2018), which were formed in post-orogenic extension of the Hegenshan Ocean (Lu et al, 2019(Lu et al, , 2020. In addition, the bojite and syenogranite contain no Precambrian inherited zircons, but show coincident high ε Hf (t) and ε Nd (t) values with young model ages, indicating that there was likely no Precambrian basement.…”

“…All the rocks from the SMACM and BAAC have clearly positive ε Hf (t) and ε Nd (t) values, indicating their magma source was contributed to by the mantle and/or juvenile continental materials. Combining pre-existing data from the literature about late Paleozoic sandstones and the Carboniferous−Permian magmatism from the SMACM and BAAC (Lu et al, 2019(Lu et al, , 2020 and that about the Daqingpasture−Diyanmiao ophiolite mélange on the southern margin of the BAAC (Liu et al, 2013;Wang et al, 2017Wang et al, , 2018aWang et al, ,b, 2019, a Carboniferous palaeostructural framework of continental arc (the SMACM)−back-arc basin (the HBAB)−arc margin (the BAAC) was proposed at the southern margin of the South Mongolian Microcontinent. After collision between the SMACM and BAAC at the end Carboniferous (Lu et al, 2019(Lu et al, , 2020, controlled by northward subduction of the Paleo-Asian Ocean, syn-to post-collisional magmatism occurred on the SMACM, while continental arc magmatism occurred on the BAAC.…”

“…(1) The north continental marginal arc on the southern margin of the South Mongolian Microcontinent shows a continental arc-back-arc basin system (Lu et al, 2019(Lu et al, , 2020 (Fig. 15).…”

“…'one narrow ocean basin of the PAO', 'two continental marginal arcs on its northern and southern' and 'one intra-oceanic arc in its southern', was established to illustrate the setting of the intra-oceanic arc magmatic rocks in the Ar-Horqin arc, as well as those of the arc magmatic rocks in the BAAC and BA. The model is inspired after Xiao et al (2003Xiao et al ( , 2018 and Lu et al (2019Lu et al ( , 2020. Names of tectonic units are noted in Fig.…”