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Cenozoic Tectonic Evolution of Major Sedimentary Basins in Central, Northern, and the Gulf of Thailand |
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| รหัสดีโอไอ | |
| Creator | Punya Charusiri |
| Title | Cenozoic Tectonic Evolution of Major Sedimentary Basins in Central, Northern, and the Gulf of Thailand |
| Contributor | Somchai Pum-Im |
| Publisher | Department of Geology, Chulalongkorn University |
| Publication Year | 2552 |
| Journal Title | Bulletin of Earth Sciences of Thailand (BEST) |
| Journal Vol. | 2 |
| Journal No. | 2-Jan |
| Page no. | 40-62 |
| Keyword | Cenozoic, Tectonic, Basins, Thailand |
| URL Website | https://www.bestjournal.org/ |
| Website title | Bulletin of Earth Sciences of Thailand |
| ISSN | 1906-280X |
| Abstract | In Thailand all major N-S trending Cenozoic basins are inferred to have developed in LateEocene to early Oligocene as a result of the 'extrusion' tectonics of Southeast Asian block alongthe major NE-SW trending fault zones. These pull-apart basins in Thailand and nearby can begrouped based upon geomorphology, sequence stratigraphy, structural styles, geographicaldistribution, and geotectonic evolution into 6 segments viz. (1) isolated, basinal Northwest &West Segment, (2) intermontane faulted-bounded northern Segment, (3) large alluvial plaindominatedCentral Segment, (4) basin-bearing plateau-type Northeastern Segment, (5) isolated,narrow intermontane Southern Segment, and (6) fault-bounded, largely subsided Gulf Segments.Individual segments can be divided into various sub-segments and several small basins.Stratigraphic evolution of the deposition system of Thailand basins active during EarlyTertiary, commenced with initial localized lacustrine and alluvial deposition in the Oligocene.Subsequent stratigraphy is dominated by sedimentation with significant hydrocarbon- and carbonproneunits, starting with fluvial and alluvial deposition in the lower unit (<100 to 2,500 m thick)in some basins and switched to transgressive fluvial and marginal marine deposition (<500 to1,000 m thick) in the middle, and terminated by the overall regressive fluvial and alluvialdeposition in the upper unit. The youngest sequence is dominated by alluvial and marginal marinesediments occurring in the Late Miocene to Pliocene.Both 40Ar - 39Ar and K-Ar geochronological data together with fission - track datinginformation on rocks collected immediately at or close to these faults, indicate that the faults mayhave been reactivated episodically since very Late Cretaceous to Early Tertiary, and in turn givenrise to several episodes of basin development.Two major fault zones include NW -trending Three-Pagoda and Mae Ping Faults in the northand the conjugate, NE-trending Ranong and Klong Marui Faults in the South. The N-trendingfaults may have been developed in response to the principal strike-slip movement, and mostly theyare normal with basement-involved listric and antithetic faults.Four main tectonic episodes for major Cenozoic Basin development in Thailand arerecognized. The first episode is the pull-apart and initial transtensional synrifting event (55 - 35)Ma) with the occurrence of rift sediments deposited by continental extension and mantle plumedue to a change from continental margin to subduction for the interaction of India and Asia. Thisepisode is marked at the end by the Middle Tertiary unconformity (MTU). The second episode isthe quiescent thermal subsidence event (35 - 15 Ma) involving the significant transtensionalcomponent with rapidly basinal subsidence and widening by withdrawal of heat from the back-areregion (the Gulf and the Andaman Sea) as well as widespread transpression and extensive deltaprogradation. Several basins were occupied by several fresh water lakes and marshes during thattime, giving rise to carbon/hydrocarbon accumulation. The third episode is characterized bytranspression wrenching event (15 - 10 Ma) due to the on-going dextral shear along the majorNW-trending fault zones with subsequent basin inversion and folding resulting in a decrease andmore uniform subsidence rate and extensive basin highs with concomitant volcanism. Thetermination of this event is marked by the late Middle Miocene unconformity (MMU). The lastepisode is denoted by post-rifting event (10 Ma -Recent), thereby the entire region may have beentectonically adjusted. Onshore basins became inversed with terrestrial deposits covered whereasthose in the Gulf were gradually and intermittently subsided with marine incursion without anysignificant hydrocarbon potentials. |
