Tectonic evolution of Palaeozoic terranes in West Junggar, Xinjiang, NW China

Abstract

Nine separate Cambrian to Carboniferous terranes are recognized in West Junggar, northwest China. They were amalgamated as part of the Central Asian Orogenic Belt which records accretion of continental, island-arc and oceanic terranes to Archaean-Proterozoic continental nuclei. Tangbale, Kekesayi, Ebinur and Mayila terranes (Cambrian-Silurian) evolved in intra-oceanic settings and docked, along a series of north-dipping subduction zones, on to the Laba terrane to their south. This southern continent was contiguous with lithosphere of the Kulumudi Ocean to the north. Devonian subduction on the northern edge of this ocean resulted in formation of a continental arc (Toli terrane) and accretionary complex (Kulumudi terrane). The Karamay terrane formed as an accretionary complex during the Carboniferous. The ophiolitic Sartuohai terrane was emplaced as m~lange between Kulumudi and Karamay terranes during the Late Carboniferous. Subduction migrated southward, continuing beneath these terranes, resulting in the intrusion of I-type granites into the Toli, Kulumudi, Sartuohai and Karamay terranes. These granites are closely associated with epithermal and porphyry-style gold mineralization. Composite terranes either side of the Kulumudi Ocean collided in the Late Carboniferous, marking the final consolidation of Central Asia. Collision was accompanied by anorogenic granite and diabase dyke intrusion, followed by widespread latest Carboniferous to Permian extension, and subsequently the formation of the Junggar Basin. West Junggar has been further disrupted by Cenozoic strike-slip faulting along Junggar and Dalabute faults.

Asthenosphere–lithosphere interaction triggered by a slab window during ridge subduction: Trace element and Sr–Nd–Hf–Os isotopic evidence from Late Carboniferous tholeiites in the western Junggar area (NW China)

“…Moreover, such an enriched deep asthenosphere is similar to the source of the Late Carboniferous OIB-type alkaline basalts in the western Junngar (Fig. 3) (Buckman and Aitchison, 2004;Liu et al, 2009;Zhang, 2009 Os compositions (Shirey and Walker, 1998). For the Hatu basalts in an intra-oceanic arc setting (e.g., Geng et al, 2009;Tang et al, 2010Tang et al, , 2012a Os ratio higher than 0.14 have average Os contents of 3.5 ± 2.4 pg/g) (Escrig et al, 2005 Os ratios may have been slightly modified by shallow level contamination.…”

Geochemistry, zircon U–Pb ages and Lu–Hf isotopes of early Paleozoic plutons in the northwestern Chinese Tianshan: Petrogenesis and geological implications

“…Therefore, it implies that northward subduction of Junggar Ocean approximately happened in the early Paleozoic in the southern West Junggar. In the Tangbale region, a middle Ordovician structural style where numerous south-vergence repeat the thin stratigraphic succession are typical of that seen in an accretionary wedge (Buckman and Aitchison, 2004). Moreover, a Pb isotope age of 471 Ma was reported for metamorphosed terrigenous clastic rock from Tangbale (Wang, 1996).…”

“…It means that some island arcs probably distributed along the southern West Junggar. Definitely, calc-alkaline island-arc igneous rocks of middle-late Ordovician developed in the Suyuenka Complex in Ebinur terrane (Buckman and Aitchison, 2004). Moreover, calc-alkaline late Cambrian (493-501 Ma) and early Ordovician (448-488 Ma) intrusive rocks have been discovered in the southwest West Junggar (Xu et al, 2012).…”

Universal Elemental Homology in Glyptocystitoids, Hemicosmitoids, Coronoids and Blastoids: Steps Toward Echinoderm Phylogenetic Reconstruction in Derived Blastozoa

“…Buckman and Aitchison (2004) hypothesize a complex amalgamation-history of intra-oceanic island arcs and continental fragments to become part of the CAOB prior to the end of the latest Carboniferous. The tectonics and ophiolite belts of northern Xinjiang and especially the Hoxtolgay area and how these may relate to the Central Asian Orogenic Belt have not been foci of our research.…”