An overview on the structures, tectonics and magmatic activities in North Vietnam

Abstract

Reconstruction of paleo-geodynamic framework of Vietnam in the relation to major tectonic events in southeast Asia reveals that Paleozoic structures in Northern Vietnam (from northeastern Song Ma suture zone northward) were developed in the southern and southeastern margins of the Yangtze Block. Northern Vietnam is divided into two major folding systems, based on their positions relative to the Song Hong fault zone. The most important structural elements in northern Vietnam are Precambrian massifs including the Phan Si Pan uplift, the Late Paleozoic – Early Mesozoic Song Da – Tu Le continental rift. Many of the volcanic basins previously determined as Mesozoic have been added to Paleozoic Song Da rift volcanic groups as newly evidence of Permian – Triassic age from sedimentary, volcanic and subvolcanic formations in the Tu Le Basin coming to light. Meanwhile several major tectonic units are classifi ed in Northeastern Vietnam. These include the Song Chay dome – outcrop of Yangtze massif’s basement that was reactivated during the Permian – Triassic, and the surrounding Paleozoic folding structures such as Lo Gam and Phu Ngu. The latter are viewed as various erosion terraces of the Song Chay dome. The Paleozoic structures are surrounded by the Masozoic Song Hien and An Chau basins, and by the circle-shaped Yen Minh – Phu Luong fault zone.