Neoproterozoic to Early Triassic tectono-stratigraphic evolution of Indochina and adjacent areas: A review with new data

Tri Van Tran (1) , Michel Faure (2) , Vuong Van V Nguyen (3) , Hoang Huy H Bui (4) , Michael Bryld Wessel B W Fyhn (5) , Tuan Quang Q Nguyen (4) , Claude Lepvrier (6) , Tonny B Thomsen (5) , Kenichiro Tani (6) , Punya Charusiri (7)

1 Vietnam Union of Geological Sciences
2 Géodynamique - UMR7327
3 USTH - University of Science and Technology of Hanoi
4 Vietnam Petroleum Institute
5 GEUS - Geological Survey of Denmark and Greenland
6 National Museum of Nature and Science
7 Chulalongkorn University [Bangkok]

The Neoproterozoic to Early Triassic tectono-stratigraphic evolution of Indochina and adjacent areas can be divided into six mega-episodes: 1) The Neoproterozoic-Early Cambrian mega-episode was characterized by shallow marine environment in the Sino-Vietnam composite terrane. Meanwhile, the different blocks of the Indochina composite terranes were still separated by branches of the Proto-Tethys. Sino-Vietnam and part of Indochina amalgamated along the Proto-Song Ma suture by the end of the Early Cambrian. 2) During the Middle Cambrian-Early Ordovician mega-episode, shallow shelf carbonate deposition prevailed north of the Proto-Song Ma suture with associated strata containing a rich benthic fauna. This contrasts with deep marine and volcanic arc setting in the south of the Proto-Song Ma suture. 3) The Middle Ordovician-Silurian mega-episode was characterized by subduction of the Tam Ky-Phuoc Son Ocean beneath the Viet-Lao terrane in the north and the Kon Tum terrane in the south. This was followed by a collisional orogeny that sutured the Kon Tum terrane with the Viet-Lao and Viet-Cambodia terranes along the Tam Ky-Phuoc Son suture. The hypothetic Po Ko and Chu Sinh sutures are discussed. The collision led to an intra-continental orogeny in the Sino-Vietnam composite terrane. By the end of the mega-episode, a unified Sino-Vietnam-Indochina super-terrane was established. During the latest Silurian-Early Devonian, benthic fauna and flora of the Sino-Vietnam and Indochina composite terranes shared Cathaysian affinity. 4) The Devonian-Tournaisian mega-episode was characterized by an Early-Middle Devonian transgression and a Late Devonian-Earliest Carboniferous regression, except for parts of northern Indochina where deep marine conditions remained. 5) During the Visean-Middle Permian, the Song Ma ocean reopenned in the north of Indochina. Meanwhile in the west, a volcano-plutonic belt formed due to eastward subduction of the Paleo-Tethys under the Indochina composite terrane. 6) The Late Permian-Early Triassic mega-episode was characterized by Emeishan mantle plume related continental rifting, and the Indosinian orogeny resulting from resuturing of the Indochina and Sino-Vietnam composite terranes along the Song Ma suture.

Mots clés: Indochina composite terrane; Sino-Vietnam composite terrane; Paleozoic tectono-stratigraphy; Song Ma suture; Tam Ky-Phuoc Son suture

Domaines: Tectonique; Stratigraphie

Tri Van Tran, Michel Faure, Vuong Van V Nguyen, Hoang Huy H Bui, Michael Bryld Wessel B W Fyhn, et al.. Neoproterozoic to Early Triassic tectono-stratigraphic evolution of Indochina and adjacent areas: A review with new data. Journal of Asian Earth Sciences, 2020, 191, pp.104231. ⟨10.1016/j.jseaes.2020.104231⟩. ⟨insu-02434825⟩