The South China block-Indochina collision: Where, when, and how?

Abstract

This study uses new field observations and existing studies to shed new light on the origin and significance of two NW-SE striking orogens in NW and NE Vietnam. We conclude that the architecture of each belt is a stack of NE-directed nappes formed either under deep ductile synmetamorphic conditions, or under shallow depth in the SW and NE parts, respectively. The Song Ma zone and Song Chay ophiolitic melange represent two ophiolitic sutures. However, the Late Permian Song Da and Babu mafic rocks are not ophiolites but intraplate basalts related to the Emeishan plume. A Late Triassic unconformity, the 225-205 Ma postorogenic plutonism, and the 250-230 Ma syntectonic metamorphism support an Early to Middle Triassic age for these tectonic events. Both NW and NE belts are due to SW-directed subduction with arc magmatism, ocean closure, and continental collision. Though two contemporary S-dipping subduction zones might

Where was the Ailaoshan Ocean and when did it open: A perspective based on detrital zircon U–Pb age and Hf isotope evidence

“…1) (Metcalfe, 2006;Faure et al, 2014). These blocks are usually regarded to have been derived from the northwestern Gondwana margin as three successive strips of continental blocks separated during the Paleozoic to Early Mesozoic.…”

Detrital zircon U-Pb geochronology and Lu-Hf isotopic compositions of the Wuliangshan metasediment rocks in SW Yunnan (China) and its provenance implications

“…The SE Asia has been assembled by a series of collision and accretion processes involving numerous continental blocks or fragments separated from the East Gondwana since the Paleozoic (Faure et al, 2014;Metcalfe, 2006). The catchment areas of the Lancang, Jinsha and Nujiang rivers (also named Sanjiang in Chinese literature) in SW Yunnan (SW China) have preserved abundant paleotethyan heritages (e.g., the Lincang giant igneous zone) at which kilometer-thick Triassic volcanic rocks and Upper Triassic/Lower Jurassic molasse sediments are considered to have resulted from closure of the Paleotethys main ocean and subsequent continental collision (Peng et al, 2008(Peng et al, , 2006 Jian et al, 2003a, b;Mo et al, 1998;Zhong, 1998; Cong et al, 1993;Mahawat et al, 1990;Liu et al, 1989;Zhang et al, 1985).…”

General characteristics of rare earth and radioactive elements in Dong Pao deposit, Lai Chau, Vietnam

“…A sedimentary sequence in the Dong Pao area is composed of Devonian siltstonemudstone formation, Permian limestones, and bauxites, and iron-bearing formations covered conformably by Early and Middle Triassic fine grained grey limestone. These rocks are overlain by the Late Triassic conglomerates and sandstones and in some places with Cretaceous red beds (Tran Van Tri, 2011;Żelaźniewicz et al, 2013;Faure et al, 2014;Halpin et al, 2015). According to Nguyen Tien Du et al, 2011, there are 17 ore bodies in the studied area.…”