Advances in Earth Science ›› 2022, Vol. 37 ›› Issue (3): 277-289. doi: 10.11867/j.issn.1001-8166.2021.097
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Xinyuan WEI 1( ), Xiwu LUAN 2( ), Fanshun MENG 1, Weimin RAN 3, Yintao LU 4, Zexuan LIU 5, Jia WANG 1, Qing HU 2, Dandan ZHANG 6
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Xinyuan WEI, Xiwu LUAN, Fanshun MENG, Weimin RAN, Yintao LU, Zexuan LIU, Jia WANG, Qing HU, Dandan ZHANG. Characteristics of Tectonics and Earthquakes in the Timor Trough and Its Constraints on the Deep Plates[J]. Advances in Earth Science, 2022, 37(3): 277-289.
The Timor Trough is located at the boundary of the Eurasian and the Australian plates， in the outer Banda Arc between the Banda Sea in Southeast Asia and the Timor Sea in northwest Australia. Since the Neogene， especially from the Late Miocene to the Late Pliocene， the collision between the Australian continent and the Banda Arc caused the uplift of Timor Island and the deformation of the Timor Trough， which affected the regional tectonic activities. A series of normal faults developed at the margin of the Australian Northwest shelf， which mainly controls the platform， horst， and graben features. The northern Timor Trough formed a series of thrust faults under the dual effect of the uplift of Timor Island and subsidence of the Timor Trough caused by arc continental collision. The NE-SW thrust fault at the bottom of the Timor Trough is the deformation front that controls the shape of the trough. The characteristics of tectonics and earthquakes indicate that the Banda subduction zone between the Australian Plate and Banda Arc is located in the Ombai Strait， which is between Timor Island and the inner Banda Arc， subducting at an average high angle of approximately 62° at a depth of more than 600 km. The subduction angle in the south is larger than that in the north， which is related to the compression of the Indian Ocean subduction plate. The front oceanic crust subducted below the northwest Banda Sea showed a horizontal trend below 500 km. There is an obvious discontinuity in the earthquakes between the deep and upper focus zones. The subduction of the Australian Plate beneath the Southeast Asian Plate may have gradually slowed down and stopped； however， the deformation of Timor Island and the Timor Trough caused by arc continental collision continues. The inner Banda Arc is deforming along the Banda Sea. Under the background of relatively balanced subduction， the subduction of the Australian Plate beneath the Southeast Asian Plate may have transformed into an orogeny. In the future， the inner Banda Arc may be uplifted to form an inner and outer Banda Arc double orogenic belt.