Micro‐Blocks in NE Asia Amalgamated Into the Unified Amuria Block by ∼300 Ma: First Paleomagnetic Evidence From the Songliao Block, NE China

Abstract

The region known as the Central Asian Orogenic Belt (CAOB) is described a collage of crustal elements that resided in an "archipelagic ocean" following the breakup of Rodinia until the assembly of Pangea (750-250 Ma) (e.g.,

New Early Permian Paleomagnetic and Geochronological Data From the Xilinhot–Songliao Block and Their Implications for the Relationship Between the Paleo‐Asian Ocean and the Paleo‐Tethys Ocean

“…Owing to the lack of precise age constraints, robust paleomagnetic tests (i.e., field, reversal, or paleosecular variation (PSV)), or well‐defined tectonic units, estimates of the paleolatitude of the XSB range from ∼40°N to ∼5°N. As a result, three models have been proposed: (a) the XSB and the Mongolian Block (MOB) were located at mid–high latitudes, far from the North China Block (NCB; Domeier & Torsvik, 2014; Zhang, Huang, Meert, et al., 2021); (b) the XSB was connected to the MOB and NCB at low latitudes (Zhao et al., 2013, 2020); and (c) the XSB was an independent terrane near the paleoequator (Zhang, Huang, Zhao, et al., 2021; D. Zhang et al., 2018).…”

Palaeomagnetic constraints on a Late Permian to Early Triassic final closure of thePalaeo‐AsianOcean

“…In the eastern part, the CAOB is comprised by the Mongolia, Songliao, Xilinhot and Jiamusi blocks (Figure 1b). Amalgamation of the Mongolia, Songliao and Jiamusi blocks along the Hegenshan‐Heihe Suture (HHS) occurred during the Late Carboniferous to Early Permian, resulting in the formation of the Amuria composite continent in NE Asia (Figure 1b; Zhang, Huang, Meert, et al, 2021). Among these blocks, the Mongolia Block was formed by the early Palaeozoic accretion and collision of the Erguna Block and South Mongolia‐Xing'an Belt (SMXB; Li, 2006; Liu et al, 2017).…”

“…(a) Stratigraphic sequences of the southern Great Xing'an Range (after IMBGMR, 1991; Ren et al, 2020 and Zhang, Huang, Meert, et al, 2021) and geomagnetic polarity time scale of the Middle‐Late Permian (Hounslow & Balabanov, 2016); (b–f) Field photos of the Upper Permian Linxi Formation in the Linxi and Taohaiyingzi sampling sections…”

“…(a) Global map showing the extent of the Central Asian Orogenic Belt (CAOB; after Xiao et al, 2018); (b) Tectonic division of the CAOB (modified after Huang et al, 2018; Liu et al, 2017; Xiao et al, 2018; Zhang, Huang, Meert, et al, 2021). HHS, Hegenshan‐Heihe Suture; SMXB, South Mongolia‐Xing'an Belt…”

“…Palaeolatitudinal information of continental blocks in ancient time can be retrieved using palaeomagnetism, and thereby constrains the spatial–temporal movements and relative positions of different blocks. According to available palaeomagnetic studies, final closure time of the PAO also spans a wide time interval, including the Late Devonian (Zhao et al, 2013), the Early Permian (Zhao, Appel, & Xu, 2020; Zhao, Appel, Xu, & Sukhbaatar, 2020), the Late Permian to Early Triassic (Huang et al, 2018; Kravchinsky, Sorokin, & Courtillot, 2002; Ren et al, 2020; Zhang, Huang, Meert, et al, 2021; Zhang, Huang, Zhao, et al, 2021; Zhang, Huang, Zhao, Meert, et al, 2018; Zhang, Huang, Zhao, & Zhang, 2018) and post Early Triassic (Didenko et al, 2016). The above discrepancy mainly results from the existence of widespread Permian to Mesozoic remagnetization in this region, unrecognized inclination shallowing in clastic rocks and inadequate average for the palaeo‐secular variation (PSV) of the Earth's geomagnetic field in volcanic rocks (Zhang, Huang, Zhao, et al, 2021; Zhang, Huang, Zhao, Meert, et al, 2018).…”