Permo-Triassic Collision, Subduction-Zone Metamorphism, and Tectonic Exhumation Along the East Asian Continental Margin

Abstract

Convergent plate motion at ∼320-210 Ma generated the Tongbai-Dabie-Sulu (east-central China)-Imjingang-Gyeonggi (central Korea)-Renge-Suo (Southwestern Japan)-Sikhote-Alin orogen along the paleo-Pacific edge of cratonal Asia. This amalgamated belt reflects collision between the Sino-Korean and Yangtze cratons on the SW portion, and accretion of outboard oceanic arcs ± sialic fragments against the NE margin. Subducted Proterozoic-Paleozoic continental and oceanic crustal complexes underwent high-and ultrahigh-pressure metamorphism at low to moderate temperatures. Tectonic slices of sialic crust episodically disengaged from the downgoing plate and, driven by buoyancy, ascended rapidly to midcrustal levels from depths exceeding 90-200 km after continental collision in east-central China plus or minus Korea, and from ∼30-50 km after arrival of far-traveled oceanic terranes in SW Japan and the Russian Far East. On achieving neutral buoyancy and stalling out at 10-20 km depth, later doming, gravitational collapse, and erosion exposed parts of the high-and ultrahigh-pressure complexes. This curvilinear orogen has been segmented and offset by major and minor transverse faults. Also, regional backarc spreading opened marginal basins behind the Permo-Triassic convergent suture zone, further disturbing portions oceanward.

Early Cretaceous dioritic rocks in the Tongling region, eastern China: Implications for the tectonic settings

“…When the paleo-Pacific plate subduction reached the Yangtze craton, it encountered the mountain root of the Dabie orogen and the North China craton in the north and northwest (e.g. Ernst et al, 2007;Huang and Zhao, 2006). Such a tectonic switch from the Late Jurassic transpressive to the Early Cretaceous extensional regimes in eastern China was considered to be related to the change from the oblique, shallow subduction of the Izanagi Plate to the orthogonal, steep subduction of the Pacific Plate (Zhu et al, 2010).…”

Diverse P–T paths of the northern Dabie complex in central China and its reworking in the early Cretaceous

“…The intensity of this event masked possible earlier metamorphic events. Thus, until recently, the tectonic nature of the NDC in particular whether Triassic subduction and HP/UHP metamorphism played a role has been an issue (Ernst et al, 2007;Jahn and Chen, 2007;Zhang et al, 2009). Different proposals have been put forward for the NDC such as: (1) it is the upper part of the subducted plate (Maruyama et al, 1994;Ernst and Liou, 1995); (2) it belongs to a Palaeozoic magmatic arc complex (Zhai et al, 1995) or part of the hanging wall of the North China block without UHP metamorphism; (3) it represents a Cretaceous extensional magmatic complex (Hacker et al, 1998Ratschbacher et al, 2000); (4) it represents a Jurassic migmatite dome (metamorphic core complex) involving Triassic subduction and UHP metamorphism (Faure et al, 1999;Zhong et al, 1999); (5) it is an extension of the Yangtze craton unaffected by the Triassic UHP metamorphism (Bryant et al, 2004); or (6) it belongs to part of the Yangtze plate that experienced Triassic deep subduction and UHP metamorphism Xu et al, 2000Xu et al, , 2005Liu et al, 2001cLiu et al, ,d, 2005Liu et al, , 2007aMalaspina et al, 2006).…”

Petrogenesis of the early Cretaceous volcanic rocks in the North Huaiyang tectono-magmatic unit of the Dabie Orogen, eastern China: Implications for crust–mantle interaction

“…Xu et al, 2002;Ma et al, 2004). It is not merely one of the largest and best-exposed UHP metamorphic terrane on the Earth (Ernst et al, 2007), but also one of the regions with the most profound occurrence of Mesozoic magmatism (Jahn et al, 1999;Zhao and Zheng, 2009). Deciphering the nature of magma source and geodynamic setting of these igneous rocks (especially mantle-derived mafic rocks) can provide insights into the complex crust-mantle interaction above the continental subduction zone, and have important bearing on the recycling of subducted crustal materials with respect to the evolution of overlying subcontinental lithospheric mantle (SCLM) (Zheng, 2012).…”