SUMMARY

Overview on the geologic evolution of Vietnam and adjacent areas: new insights

Trần Văn Trị, Bùi Minh Tâm, Đào Thái Bắc, Nguyễn Bá Minh,

Nguyễn Thị Bích Thủy, Nguyễn Văn Vượng, Nguyễn Xuân Bao,

Phạm Đức Lương, Trần Trọng Hòa

The geologic evolution of Vietnam and adjacent areas is divided into 8 time intervals as follows: 1) Meso-Neoarchean (3230-2500 Ma): represented by part of the Suoi Chieng and Ca Vinh Archean core preserved in the Hoang Lien Son craton; 2) Paleo-Mesoproterozoic (2500-1300 Ma): the Cathaysia, Yangtze-Hoang Lien Son, Indosinia (including Hoang Sa) cratons amalgamated and broke up related to the formation of Nuna super-continent; 3) Meso-Neoproterozoic (1300-750 Ma): formation of the Sino- Vietnam composite terrane related to the amalgamation and break-up of the Rodinia super-continent; 4) Middle Neoproterozoic-Early Cambrian (750-520 Ma): subduction of a branch of Proto-Tethys led to collision of the Phu Hoat micro-continent with the Sino-Vietnam composite terrane, forming the protoSong Ma suture zone, related to the amalgamation and break-up of the Gondwanna super-continent; 5) Cambrian-Silurian (520-420 Ma): the subduction and volcanic arc of Quang Nam to the north and Quang Ngai to the south, collision and suturing across the Tam Ky-Phuoc Son suture zone during 450-440 Ma, followed by separation of Indosinia from Peri-Gondwanna at the end of the Silurian; 6) Devonian-Late Triassic (400-215 Ma): the Song Ma Paleotethys ocean reopened in the Middle Devonian at 380 Ma, closed in the Late Permian-Early Triassic at 250 Ma due to the Indosinian orogeny, meanwhile the Late Carboniferous-Early Permian volcanic arc formed along the western margin of Indochina, and plume- related high to ultra-high metamorphism occurred at the Kon Tum terrane; 7) Late Triassic-Cretaceous (215-65 Ma): intra-continental tectonics dominated, forming Middle-Late Triassic rifts and Late Triassic- Early Jurassic coal-bearing basins. Marine regime ended in the Norian in North Vietnam while it persisted until the Early-Middle Jurassic in South Vietnam. The Nan-Sra Kaeo marginal sea closed, Sibumasu collided with the Sukhothai arc forming the Indochina composite terrane and connected with the Sundaland continent. In the Late Jurassic-Cretaceous, the Da Lat volcanic-pluton arc formed, as well as continental basins were filled with red bed and evaporite deposits in Laos and Thailand. 8) Paleogene- Quaternary (65-0 Ma): the collision of India with Eurasia caused the extrusion of Indochina along NW- SE left-lateral strike-slip faults, forming Cenozoic basins, Vietnam East Sea seafloor spreading, and dispersed basalt province as well as widespread volcanism in a large part of Indochina and the Hainan island.

Keywords: Geologic evolution; Indochina, Sino-Vietnam composite terranes; Indosinia; the SongMa and Tam Kỳ - Phước Sơn suture zones.