| Session Details | |
| Section | SE - Solid Earth Sciences |
| Session Title | Effects of India-Asia collision on evolution of Southeast Asia |
| Main Convener | Dr. Nguyen Hoang (Institute of Geological Sciences, Vietnam Academy of Sciences and Technology, Viet Nam) |
| Co-convener(s) | Prof. Christoph Hauzenberger (University of Graz, Austria) Dr. Isoji Miyagi (Geological Survey of Japan, National Institude of Advanced Industrial Science and Technology, Japan) Prof. Jürgen Konzett (University of Innsbruck, Austria) Prof. Martin Flower (University of Illinois at Chicago, United States) Dr. Bradley Ritts (Chevron Asia-Pacific, Singapore) Prof. Pete Lippert (University of Utah, United States) |
| Session Description | The evolution of Southeast Asia, especially Indochina, offers numerous examples traceable to the Early Tertiary India-Asia collision. Geodynamic effects of the collision include uplift and intense erosion, crustal shortening and thickening, lateral extrusion of both lithosphere and asthenosphere. The most intensively studied feature in the region are a set of NW-SE trending large scale shear zones (e.g., Ailao Shan-Red River, Mae Ping, Three Pagoda shear faults) which certainly accommodated the southeastward extrusion of Indochina and subsequent opening of East Viet Nam (South China) Sea during the Late Oligocene and Miocene, followed by the eastward escape of South China. The most compelling evidence for this is a 600-700 km offset of Permo-Triassic mafic-ultramafic and related lithologies along the Song Da lineament (between Song Ma and Red River in Viet Nam), extending from the Emeishan large igneous province in southwestern China to the Gulf of Northern Viet Nam. Their genesis remains a puzzle, however, depending on whether or not the magmas were produced in response to a deep mantle plume. In contrast, it is well established that the voluminous intraplate basaltic magmas in Indochina and elsewhere in East and Southeast Asia erupted after c. 20 Ma coincided with the cessation of Indochina extrusion and seafloor spreading in the East Viet Nam Sea. The widespread Cenozoic basalt magmatism can be plausibly linked to mantle perturbations resulting from the Indian collision in turn providing a mechanism for driving lithospheric ‘escape’ and coeval opening of marginal basins such as the East Viet Nam Sea. This brief description is intended to indicate the diversity of potential interpretations and the proposed session provides an opportunity for discussion from a multidisciplinary standpoint. We therefore invite contributions from geoscientists working in structural geology, paleomagnetism, landscape evolution, seismology, sedimentology, petrology, geochronology and geochemistry, etc., in attempting to clarify the collision’s impact with regard to key geologic features in the region. |