Structural and stratigraphic evolution of the Savu Basin, Indonesia
James W. D. Rigg, Robert Hall, 2011. "Structural and stratigraphic evolution of the Savu Basin, Indonesia", The SE Asian Gateway: History and Tectonics of the Australia-Asia Collision, R. Hall, M. A. Cottam, M. E. J. Wilson
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The Savu Basin is located in the Sunda–Banda fore-arc at the position of change from oceanic subduction to continent–arc collision. It narrows eastward and is bounded to the west by the island of Sumba that obliquely crosses the fore-arc. New seismic data and published geological observations are used to interpret Australia–Sundaland convergence history. We suggest the basin is underlain by continental crust and was close to sea level in the Early Miocene. Normal faulting in the Middle Miocene and rapid subsidence to several kilometres was driven by subduction rollback. Arc-derived volcaniclastic turbidites were transported ESE, parallel to the Sumba Ridge, and then NE. The ridge was elevated as the Australian continental margin arrived at the Banda Trench, causing debris flows and turbidites to flow northwards into the basin which is little deformed except for tilting and slumping. South of the ridge fore-arc sediments and Australian sedimentary cover were incorporated in a large accretionary complex formed as continental crust was thrust beneath the fore-arc. This is bounded to the north by the Savu and Roti Thrusts and to the south by a trough connecting the Java Trench and Timor Trough which formed by south-directed thrusting and loading.
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Collision between Australia and SE Asia began in the Early Miocene and reduced the former wide ocean between them to a complex passage which connects the Pacific and Indian Oceans. Today, the Indonesian Throughflow passes through this gateway and plays an important role in global thermohaline flow. The surrounding region contains the maximum global diversity for many marine and terrestrial organisms. Reconstruction of this geologically complex region is essential for understanding its role in oceanic and atmospheric circulation, climate impacts, and the origin of its biodiversity.
The papers in this volume discuss the Palaeozoic to Cenozoic geological background to Australia and SE Asia collision. They provide the background for accounts of the modern Indonesian Throughflow and oceanographic changes since the Neogene, and consider aspects of the region’s climate history.