Geochronology and geochemistry of the Niujuanzi ophiolitic mélange, Gansu Province, NW China: implications for tectonic evolution of the Beishan Orogenic Collage

Early Paleozoic Ocean Plate Stratigraphy of the Beishan Orogenic Zone, NW China: Implications for Regional Tectonic Evolution

“…Red areas represent Archaean to Palaeoproterozoic rocks. Yellow-brown area surrounding Siberian Craton is late Meso-to Neoproterozoic part of the CAOB; (c) diagram showing the boundaries of tectonic units in the Beishan orogenic zone (modified by Guo et al, 2014;Wang et al 2017), ① Hongshishan-Baiheshan ophiolite zone, ② Jijitai-Xiaohuangshan ophiolite zone, ③ Hongliuhe-Niujuanzi-Mazongshan-Xichangjing tectonic mé lange zone, ④ Liuyuan ophiolite zone.…”

“…In this paper, we reconstruct the Xichangjing-Yueyashan ophiolite mé lange (data from Hu et al, 2016), the Mazongshan accretion complex (data from Wang et al, 2020; shown in Fig. 9), the Niujuanzi ophiolite mé lange (data from Wang et al, 2017; shown in Figure 8) and the Lebaquan forearc-arc complex in the central part of HNMX (data from Song et al, 2014; shown in Fig. 9).…”

“…Thus this portion is a dismembered ophiolite that lacks several parts of the standard definition of an ophiolite, such as perdotites and bedded chert. The MOR ophiolite blocks are in fault contact with the sandstone, suggesting a segment of mid-ocean ridge incorporated in an active trench (Wang et al, 2017). Compared to the block in the HNMX, the high precision chronology of the matrix is obviously deficient.…”

“…10). Such MOR-type basalts described from the Hongliuhe-Niujuanzi-Xichangjing area are interpreted to be the lowest part of the formation corresponding to ocean floor rocks (Zhang et al, 2008;Ao et al, 2012;Hu et al, 2014;Wang et al, 2017Wang et al, , 2020. The southern oceanic sediments span a period of nearly 80 million years from late Cambrian to early Silurian.…”

The Dashui Subduction Complex in the Eastern Tianshan‐Beishan Orogen (NW China): Long‐Lasting Subduction‐Accretion Terminated by Unique Mid‐Triassic Strike‐Slip Juxtaposition of Arcs in the Southern Altaids

“…The Tianshan‐Beishan Orogen (TBO) constitutes the middle part of the southern margin of the Altaids, connecting the Solonker suture to the east and the South Tianshan suture to the west (Figure 1) (Li, 2004; Sengör et al., 1993; Windley et al., 2007; Xiao et al., 2015, 2010b; Zuo & Li, 1996). Several arcs were amalgamated in the Late Paleozoic or Early Mesozoic (Ao et al., 2021; Mao et al., 2021), and displaced by the NE‐trending Xingxingxia shear zone (Liu & Wang, 1995; Yang et al., 2009), giving rise to a complex accretionary archipelago (Chen et al., 2019; He et al., 2005; Song et al., 2015; Wang, Zhang, Song, Li, Li, Zhou, 2018; Xiao, Mao, et al., 2010; Yang et al., 2010; Zuo & He, 1990). Therefore, the TBO is in the key location for unraveling the manner and timing of arc amalgamation, and the mechanisms that led to the east‐west junction of the southern Altaids.…”