Structural frame work of the fore-arc basin, NW Sumatra
- 1 January 1980
- journal article
- Published by Geological Society of London in Journal of the Geological Society
- Vol. 137 (1) , 77-91
- https://doi.org/10.1144/gsjgs.137.1.0077
Abstract
The fore-arc basin of the Sunda Arc off Sumatra is a strongly subsiding trough contained between the rising subduction complex and the elevated continental core. Up to 4 km of Miocene–Recent strata on the eastern flank of the basin have transgressed over an unconformity cut across a Palaeogene continental margin that was uplifted and structurally disrupted during the late Oligocene. The large step-like offsets of the palaeo-shelf edge, and probably some of the structural disruption, can be attributed to right-lateral strike-slip faults that splay across the fore-arc basin from the Sumatra Fault Zone. Offsets range up to 100 km+, producing marginal re-entrants that became sites of turbidite-filled basins trapped behind the growing Neogene accretionary prism. The larger re-entrants may be floored with oceanic crust, but the proximity of exposed subduction complex to the palaeo-margin precludes the existence of a continuous band of oceanic crust beneath the fore-arc basin. The seaward flank of the fore-arc basin has migrated westwards during Neogene subduction, but not so much as the trench, and in a much more complicated fashion. During the early Miocene, the inner trench slope had a juvenile terrace-like morphology. By late mid-Miocene time, the trench slope break was near sea level and formed a shelf edge high. Thrusting and folding related to subduction probably decreased gradually upslope until late-Pliocene, when large flexures and E-directed reverse faults developed, marking an arcward shift in the rear or eastern boundary of the deformation associated with subduction. The episodic development of arcward-directed structures, involving previously stabilized fore-arc basin strata, suggests periods of increased stress levels along the base of the accretionary prism.This publication has 14 references indexed in Scilit:
- Structural geology of Nias Island, Indonesia; implications for subduction zone tectonicsAmerican Journal of Science, 1980
- A review of the main structural and magmatic features of northern SumatraJournal of the Geological Society, 1979
- Characteristics of back arc spreading in the Mariana TroughJournal of Geophysical Research, 1978
- The state of stress at continental marginsTectonophysics, 1977
- Subduction in the Indonesion regionPublished by Wiley ,1977
- Cenozoic Tectonics of Asia: Effects of a Continental Collision: Features of recent continental tectonics in Asia can be interpreted as results of the India-Eurasia collisionScience, 1975
- Evolution of the East: Central Indian Ocean, with Emphasis on the Tectonic Setting of the Ninetyeast RidgeGSA Bulletin, 1974
- Plate convergence, transcurrent faults, and internal deformation adjacent to Southeast Asia and the western PacificJournal of Geophysical Research, 1972
- Structure of the Continental Margin and Tectonism at the Eastern Aleutian TrenchGSA Bulletin, 1972
- Reflection profiles across the Middle America TrenchJournal of Geophysical Research, 1965