Arc-continent collision in Banda Sea region
- Woods Hole Oceanographic Inst., MA
A 2-month marine geophysical study of the Banda arc region was conducted in late 1976 using the R/V Atlantis II of WHOI' and the R/V Thomas Washington of SIO; 19 seismic refraction lines were successfully completed. Oceanic crust underlies the Banda Sea and Weber Deep. Continental crust 35 to 40 km thick underlies the Australian Shelf. Thick continental crust is also present beneath the Timor and Aru Troughs. Low-amplitude magnetic anomalies are present over the Australian Shelf and extend to near the western edge of the Banda outer arc and, together with the presence of metamorphic rocks, suggest that continental crust may extend to the eastern lip of the Weber Deep. Continuous seismic reflection profiling shows the Australian Shelf sedimentary sequence dipping beneath the accretionary prisms of the outer Banda arc at the Timor and Seram Troughs: the tectonic front of the subduction zone lies along the axis of these troughs. The bathymetric profile on the outer flank of the Timor and Seram Troughs is unusual in that the profile asymptotically approaches a shallow depth near sea level and no outer rise is present as at oceanic trenches. It is concluded that the Outer Banda arc from Buru around to Timor, and possibly to Sumba, contained Australian continental crustal blocks and fragments prior to its collision with the Australian margin in the last 3 to 6 m.y. Continuous convergence following the addition of a thick Australian margin sedimentary sequence to the south Banda subduction zone has led to deformation being distributed over the width of the arc and not simply being taken up on a single thrust surface. This scenario helps reconcile the geologic relations on Timor, Seram, and Buru with the structural continuity of the Timor Trough with the Java Trench. 30 figures, 1 table.
- OSTI ID:
- 6925489
- Journal Information:
- Am. Assoc. Pet. Geol. Bull.; (United States), Vol. 64:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
02 PETROLEUM
AUSTRALIA
GEOPHYSICAL SURVEYS
CONTINENTAL CRUST
CONTINENTAL MARGIN
CONTINENTAL SHELF
SEA-FLOOR SPREADING
SEAS
SEDIMENTATION
SEISMIC SURVEYS
AUSTRALASIA
EARTH CRUST
SURFACE WATERS
SURVEYS
580203* - Geophysics- Geophysical Survey Methods- (1980-1989)
020200 - Petroleum- Reserves
Geology
& Exploration