Seismological constraints and speculations on Banda Arc tectonics
McCaffrey, R. (1989). Seismological constraints and speculations on Banda Arc tectonics. Neth. J. Sea Res. 24(2-3): 141-152
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, more
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| Abstract |
Fault plane solutions of shallow earthquakes show that the collision of the Australian continent with the Banda Arc shortens the overriding Indonesian plate in the north-south direction and elongates it in the east-west direction by a combination of strike-slip and thrust faulting. The shallow tectonics and the distribution of deep earthquakes beneath the Banda Basin both indicate that two plates subduct beneath the Banda Arc; the Australia-Indian Ocean plate northward beneath the Java Trench, Timor Trough, and Aru Troughs, and the Bird's Head southwestward beneath the Seram Trough. The slab of the Indian Ocean plate forms a westward plunging synform beneath the Banda Basin. Its unusual shape is interpreted to have been caused by subduction beneath the westward moving Pacific plate which transported slivers of New Guinea into the back arc. The lithosphere of the Bird's Head was subducted beneath the Seram Trough and now reaches 300 km depth. At the surface decoupling between Australian and the Bird's Head probably occurs by left-lateral strike slip at the Tarera-Aiduna fault zone in western Irian Jaya and by convergence in the New Guinea fold-and-thrust belt. Seismic quiescence occurs at depths of 50 to 380 km beneath both Timor and the inactive volcanic arc to its north but the efficient propagation of S-waves through the same volume suggests that the lithospheric slab is continuous there. The lack of seismic and volcanic activity may result from removal of part of the Australian continental crust prior to subduction of the lower part of the lithosphere. This crust was stacked up to form the island of Timor. |
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