Fyhn, Michael B.W.2; Boldreel, Lars Ole3; Nielsen, Lars H2
1 Geology, Department of Geosciences and Natural Resource Management, Faculty of Science, Københavns Universitet2 De Nationale Geologiske Undersøgelser for Danmark og Grønland3 Geology, Department of Geosciences and Natural Resource Management, Faculty of Science, Københavns Universitet
The Malay Basin represents one of the largest rift basins of SE Asia. Based on a comprehensive 2-D seismic database tied to wells covering mainly Vietnamese acreage, the evolution of the Vietnamese part of the basin is outlined and a new tectonic model is proposed for the development of the basin. The Vietnamese part of the Malay Basin comprises a large and deep Paleogene pull-apart basin formed through Middle or Late Eocene to Oligocene left-lateral strike-slip along NNW-trending fault zones. The Tho Chu Fault Zone constitutes a significant Paleogene left-lateral strike-slip zone most likely associated with SE Asian extrusion tectonism. The fault zone outlines a deep rift that widens to the south and connects with the main Malay Basin. In the central northern part of the basin, a series of intra-basinal left-lateral fracture zones are interconnected by NW to WNW-trending extensional faults and worked to distribute sinistral shearing cross the width of the basin. Extensive thermal sagging throughout the Neogene has led to the accommodation of a very thick sedimentary succession. Moderate rifting resumed during the Early Miocene following older structural fabric. The intensity of rifting increases towards the west and was probably related to coeval extension in the western part of the Gulf of Thailand. Neogene extension culminated before the Pliocene, although faults in places remains active. Late Neogene basin inversion has been attributed to c. 70 km of right-lateral movement across major c. N–Strending faults in the central part of the basin. However, the lack of inversion in Vietnamese territory only seems to merit a few kilometers of dextral inversion.
Tectonophysics, 2010, Vol 483, Issue 3-4, p. 365-376