Steven L. Dorobek¹, Christopher C. Olson¹

(1) Texas A&M University, College Station, TX

ABSTRACT: Timing of Major Uplift in the Eastern Tibetan Plateau as Recorded by Neogene Deposits of the Paleo-Mekong Delta, Offshore Vietnam

The Cenozoic uplift history of the Himalayan orogen-Tibetan Plateau has been derived from various records, each of which produces variable estimates for the exact age of major uplift and erosional unroofing in the topographically highest regions on Earth. The history of Cenozoic uplift in this important region may have influenced global climatic patterns, oceanic circulation, and sediment flux into the Indian Ocean and South China Sea.

The headwaters of the modern Mekong River are in the eastern Tibetan Plateau. Stratigraphic relationships within Neogene deposits of the paleo-Mekong Delta, offshore Vietnam, provide key evidence for the timing of drainage development and sediment flux from eastern Tibet. Limited well control and regional, multichannel seismic profiles indicate that major progradation of the paleo-Mekong Delta into the Nam Con Son Basin (offshore Vietnam) began at about 6-5 Ma, with rapid progradation continuing to the Present time. Syndepositional failure along the seaward edge of the paleo-Mekong delta occurred repeatedly during the rapid progradation. The beginning of increased progradation at 6-5 Ma suggests major uplift of the Tibetan Plateau may have begun slightly before this time. During and following Neogene uplift, the paleo-Mekong's drainage network apparently began to access the eastern Tibetan Plateau and transported sediment to the Cuu Long and Nam Con Son basins of offshore SE Vietnam.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado