Oceanic accretionary belt in the West Qinling Orogen: Links between the Qinling and Qilian orogens, China

Abstract

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Petrology and Tectonic Geophysics of Massive and Foliated Eclogites in the North Qilian Orogenic Belt: Changes in Mineral Composition, Oxygen Fugacity, and Fabric during Exhumation

“…It shows that during the reentry process, the ultra-high pressure metamorphic rocks maintained a relatively closed state, and no large-scale dispersive fluid inflow and outflow activities occurred; in addition, the existence of various fluid inclusions and veins, eclogite [22]. The heterogeneity of retrograde metamorphism, the discovery of potassium feldspar+quartz±plagioclase inclusions in eclogite, the discovery of molten structure, etc., all indicate that structural water precipitation occurred in the process of ultra-high pressure metamorphic rock and formed a local area [23]. Fluid reaction and partial melting of decompression; in terms of structure, the combination of CCSD deep drilling cores and regional outcrops allows people to more accurately understand the structural framework of the entire ultra-high pressure metamorphic body from a three-dimensional space, and the deep crust of the drilling holes can also be identified [24].…”

Pannotia: in defence of its existence and geodynamic significance

“…The ophiolitic blocks are interpreted to represent an oceanic plateau associated with a mantle plume. In the West Qinling orogen, located some 600 km to the east, ophiolites of similar age structurally overlain by marble are also interpreted to represent an oceanic plateau or seamount (Yang et al, 2018). Riftrelated mafic rocks also occur in the NW Tarim Craton where they have been attributed to an initial (failed) attempt to break up Gondwana at c. 520 Ma (Turner, 2010;Lu et al, 2018).…”

A restudy of the Sandbian to Katian (Upper Ordovician) graptolites from the East Qilianshan (Chilianshan), Northwest China

“…East Qilianshan is situated in the North Qilian Orogenic Belt (Song et al, 2013) or the North Qilian Accretionary Belt (Yang et al, 2018). The Qilian orogenic belt is located in a region at the junction of the North China Craton, the Yangtze Craton, and the Tarim Craton (Song et al, 2013).…”

“…The Qilian orogenic belt is located in a region at the junction of the North China Craton, the Yangtze Craton, and the Tarim Craton (Song et al, 2013). Both Song et al (2013) and Yang et al (2018) recognized that the North Qilian orogenic belt was a back-arc basin between the Qilian Ocean and the Alashan block during the Ordovician. Graptolite fauna in the East Qilianshan is quite different from that in the Yangtze region, especially in the late Katian.…”