PhD defence: Hoang Huy Bui
Hoang Huy Bui defends his thesis,
Cenozoic structural development of strike-slip deformation and associated basin opening in northern Indochina
An integrated approach and implications on crustal response during tectonic extrusion
Supervisors:
Associate Professor Lars Ole Boldreel, IGN
Senior Researcher Michael B. W. Fyhn, GEUS
Assessment Committee:
Senior Geophysicist C. K. Morley, PTTEP – Thailand
Associate Professor Ole Rønø Clausen, Aarhus University – Denmark
Associate Professor Kresten Anderskouv (chair), IGN
Summary:
Indochina features prominent strike-slip fault systems that originate from near the India-Eurasia collision front, stretching for hundreds to more than 1000 km into the Gulf of Tonkin. Documenting the deformation history of these strike-slip fault systems and their associated offshore basins provide crucial clues on the role of extrusion tectonics in the deformation of SE Asia. The study employs an integrated approach from field work, Unmanned Aerial Vehicle (UAV) imaging, and 2- and 3-D seismic and well interpretation to describe the structure and deformation history in the northern Song Hong Basin, the Bach Long Vy (BLV) island in the Gulf of Tonkin, the Song Ca-Rao Nay Fault System (SCRNFS) in north-central Vietnam, and the Hue Sub-basin on the western flank of the Song Hong Basin. Basin opening initiated in the Song Hong Basin in the Eocene(?)-Oligocene was associated with clockwise rotation and SE-ward translation of Indochina along the left-lateral Ailao Shan-Red River Shear Zone (ASRRSZ). On BLV island, deep-lacustrine syn-rift deposits formed in the Late Oligocene and was pervasively intruded by sand injectites . In the Late Oligocene, the SCRNFS started its right-lateral motion and opened the Hue Sub-basin. Rifting was interrupted by the End-Oligocene inversion as Indochina rotation almost ceased, causing transpression at restraining bends mainly in northern Song Hong Basin. Rifting resumed in the Early Miocene, and was more intense in the Hue Sub-basin compared to the rest of the Song Hong Basin where westward depocenter migration took place. Middle Neogene inversion affected northern Indochina due to left-lateral transpression along the ASRRSZ and SCRNFS, causing folding, uplift and erosion. The transpression occurred around the Early-Middle Miocene boundary in northern Hue Sub-basin. Onshore, the inversion is interpreted to be expressed as a distinct unconformity separating a quartz conglomerate from underlying compositionally immature conglomerates. The transpression event could relate to the SE Asia-Australia collision restricting escape movement of Indochina from the India-Eurasia collision front.
A digital version of the PhD thesis can be obtained from the PhD secretary Mikala Heckscher at mikala@ign.ku.dk