Shu Sun

Paleozoic multiple subduction-accretion processes of the southern Altaids

The formation and development of the southern Altaids is controversial with regard to its accretionary orogenesis and continental growth. The Altay-East Junggar orogenic collage of North Xinjiang, China, offers a special natural laboratory to resolve this puzzle. Three tectonic units were juxtaposed, roughly from North to South, in the study area. The northern part (Chinese Altay), composed of variably deformed and metamorphosed Paleozoic sedimentary, volcanic, and granitic rocks, is interpreted as a Japan-type island arc of Paleozoic to Carboniferous-Permian age. The central part (Erqis), which consists of ophiolitic mélanges and coherent assemblages, is a Paleozoic accretionary complex. The southern part (East Junggar), characterized by imbricated ophiolitic mélanges, Nb-enriched basalts, adakitic rocks and volcanic rocks, is regarded as a Devonian-Carboniferous intra-oceanic island arc with some Paleozoic ophiolites, superimposed by Permian arc volcanism. A plagiogranite from an imbricated ophiolitic mélange (Armantai) in the East Junggar yields a new SHRIMP zircon age of 503 ± 7 Ma. Using published age constraints, we propose the presence of multiple subduction systems in this part of the Paloasian Ocean in the Paleozoic. The intraoceanic arcs became accreted to the southern active margin of the Siberian craton in the middle Carboniferous-Permian. During the long accretionary processes, in addition to large-scale southward-directed thrusting, large-scale, orogen-parallel, strike-slip movements (for example, Erqis fault) in the Permian translated fragments of these intraoceanic arcs and associated accretionary wedges. This new tectonic model has broad implications for the architecture and crustal growth of Central Asia and for other ancient orogens.

Eight stages of major ore deposits in northern Xinjiang, NW-China: Clues and constraints on the tectonic evolution and continental growth of central Asia

Major Cu, Ni, Cr, Au, Pb, Zn, Fe, W, Sn and rare metal deposits of northern Xinjiang (China) formed during eight tectonic stages, based on their plate tectonic setting. These stages are (1) Precambrian stable continental, (2) Neoproterozoic rift stage, (3) formation of oceans, (4) Silurian-early Carboniferous subduction, (5) Devonian and Carboniferous back-arc, intra-arc extension, (6) late Carboniferous to early Permian collision, (7) Permian post-collision extension, and (8) Triassic inter-continental rift stage. Different ore deposits correspond to each evolution stage, and their formation, and associated magmatic and volcanic sedimentary sequences place important constraints on the development of a tectonic framework for the continental growth of Central Asia Orogenic Belt.

Early Mesozoic Collapse of the Late Paleozoic Archipelago in South China

Publisher Summary This chapter discusses some of the interaction among the various kinds of fragments by temporal-spatial analysis of the foreland fold-and-thrust belts, together with some other geological and geophysical data. The significance of the Permian-Early Triassic tectono-paleogeography of South China is reviewed in the light of data concerning the amalgamation of multiple blocks and the interblock basins. The Yangtze microcontinent, Simao, Lincang, Jiangnan, and Cathaysian remnant arcs, together with the various kinds of geological terranes, were sparsely distributed along the southern active margin of the Eurasian continent in Pz-T1, which is very similar to the present South East Asia archipelago. The front arc of the South China archipelago has been preferred to the southern parts of the Lincang and Cathaysian arcs. After the collapse of the interblock basins and final amalgamation of these South China blocks in the Middle Triassic, these blocks were linked by melange zones and fold-thrust belts with the main deformation time duration of T2-J. The Changning Menglian melange and the Coastal Fujian melange marked the collisional orogeny between Gondwana and Eurasia in the western and eastern parts of South China, respectively. The early Mesozoic multiblock collage process of South China gave rise to the Mesozoic continental growth of southern Eurasia.

Paleozoic reconstruction and tectonic evolution of north Xinjiang, NW China: Implications for the lateral growth of central Asia

The geology and tectonics of North Xinjiang can be divided into the Chinese Altay-East Junggar, West Junggar, and Tianshan-Tarim domains, each of which is composed of Andean-type magmatic arc or island arc, accretionary wedge, and ophiolitic slice, showing archipelago paleogeography. The Chinese Altay-East Junggar domain was more closely located to the Angaran craton (Siberia), while the Tianshan-Tarim domain was near the opposite side of the early Paleozoic Paleoasian ocean. The West Junggar domain occupied an intermediate position near the Kazakhstan block in the early Paleozoic Paleoasian basin. The Tianshan-Tarim and West Junggar domains drifted northwards and approached the Chinese Altay-East Junggar active margin of the Angaran craton in the late Paleozoic. Subsequent amalgamation of these domains squeezed the archipelago systems of these domains, leading to termination of the Paleoasian ocean and formation of a complicated orogenic collage between Angaran craton and the Tarim block by the late Carboniferous or the early Permian. These multiple accretion processes significantly contributed to the lateral growth of Central Asia.