Seismicity gaps and the shape of the seismic zone in the Banda Sea region from relocated hypocenters

Das, S.

doi:10.1029/2004jb003192

Cited by 42 publications

(56 citation statements)

References 39 publications

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“…As revealed by seismic tomography (Widiyantoro and van der Hilst, 1997;Fichtner et al, 2010;Spakman and Hall, 2010) and seismicity patterns (Cardwell and Isacks, 1978;Milsom, 2001;Das, 2004), a tear likely exists in the slab beneath Buru and western Seram (see Fig. 2) which may provide a channel for hot asthenosphere to escape from the beneath the collapsing Proto-Banda Sea.…”

Section: Resultsmentioning

confidence: 99%

“…The much smaller volcanic island of Ambon lies to Seram's immediate southwest. An outline of the geology of Seram and Ambon was first provided by early pioneers -western Seram comprises a metamorphic basement of schists, amphibolites, and gneisses associated with ultramafic complexes and unusual cordieritebearing granites (Martin, 1901;Schroeder van der Kolk, 1902;Wanner, 1907;Deninger, 1915); the Manusela Mountains of central Seram and the hills to their north and east consist mainly of extensive carbonate successions, shales, and (Das, 2004) and seismic tomography (Spakman and Hall, 2010). Eastward subduction rollback of the Proto-Banda Sea (dark purple) into a pre-existing D-shaped embayment in the Australian continental margin (light brown) is thought to explain the slab's extreme curvature.…”

Section: The Geology Of Seram and Ambon: A Synopsis Of Previous Workmentioning

confidence: 99%

“…We first provide a synthesis of previously published field reports (Valk, 1945;Germeraad, 1946;van der Sluis, 1950;Audley-Charles et al, 1979;Tjokrosapoetro and Budhitrisna, 1982;de Smet and Barber, 1992) and geophysical surveys (Milsom, 1979;Milsom et al, 2001;Bock et al, 2003;Das, 2004;Widiyantoro and van der Hilst, 1997;Spakman and Hall, 2010) combined with ASTER digital elevation model (DEM) interpretation. We present a series of new small-scale geological maps for a number of key areas around Seram alongside a revised geological sketch-map for the whole island (Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Earthquake hypocentre determination (Cardwell and Isacks, 1978;Das, 2004) combined with seismic tomography (Widiyantoro and van der Hilst, 1997;Spakman and Hall, 2010) have revealed the subducted lithosphere morphology of the Banda Arc to approximate the bow of a 500 km wide ship, sailing due east, whose hull rests on the 660 km depth mantle discontinuity (Fig. 2).…”

Section: Introductionmentioning

confidence: 99%

“…Some authors, largely based on interpretation of seismic and geochemical trends, have proposed that the geometry of the Banda Arc is created by two separate slabs -a southwarddipping slab beneath Seram forming the northern portion of the arc, and a northward-dipping slab beneath Timor forming the southern portion -which have coincidentally sutured along their junction (Cardwell and Isacks, 1978;McCaffrey, 1988McCaffrey, , 1989Stevens et al, 2002;Bock et al, 2003;Das, 2004;Hinschberger et al, 2005;Fichtner et al, 2010;Špičák et al, 2013). Although more plausible than early models that proposed the Banda Arc represents an eastward continuation of the Sunda Arc subsequently flexed through 180 • (Audley- Charles et al, 1972;Katili, 1975), these two-slab hypotheses run into problems when placed into a regional plate-tectonic context (Hall, 2002Spakman and Hall, 2010).…”

Section: Introductionmentioning

confidence: 99%

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Extreme extension across Seram and Ambon, eastern Indonesia: evidence for Banda slab rollback

2013

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Abstract. The island of Seram, which lies in the northern part of the 180 • -curved Banda Arc, has previously been interpreted as a fold-and-thrust belt formed during arc-continent collision, which incorporates ophiolites intruded by granites thought to have been produced by anatexis within a metamorphic sole. However, new geological mapping and a re-examination of the field relations cause us to question this model. We instead propose that there is evidence for recent and rapid N-S extension that has caused the hightemperature exhumation of lherzolites beneath low-angle lithospheric detachment faults that induced high-temperature metamorphism and melting in overlying crustal rocks. These "Kobipoto Complex" migmatites include highly residual AlMg-rich garnet + cordierite + sillimanite + spinel + corundum granulites (exposed in the Kobipoto Mountains) which contain coexisting spinel + quartz, indicating that peak metamorphic temperatures likely approached 900 • C. Associated with these residual granulites are voluminous MioPliocene granitic diatexites, or "cordierite granites", which crop out on Ambon, western Seram, and in the Kobipoto Mountains and incorporate abundant schlieren of spineland sillimanite-bearing residuum. Quaternary "ambonites" (cordierite + garnet dacites) emplaced on Ambon were also evidently sourced from the Kobipoto Complex migmatites as demonstrated by granulite-inherited xenoliths. Exhumation of the hot peridotites and granulite-facies Kobipoto Complex migmatites to shallower structural levels caused greenschistto lower-amphibolite facies metapelites and amphibolites of the Tehoru Formation to be overprinted by sillimanite-grade metamorphism, migmatisation, and limited localised anatexis to form the Taunusa Complex. The extreme extension required to have driven Kobipoto Complex exhumation evidently occurred throughout Seram and along much of the northern Banda Arc. The lherzolites must have been juxtaposed against the crust at typical lithospheric mantle temperatures in order to account for such high-temperature metamorphism and therefore could not have been part of a cooled ophiolite. In central Seram, lenses of peridotites are incorporated with a major left-lateral strike-slip shear zone (the "Kawa Shear Zone"), demonstrating that strike-slip motions likely initiated shortly after the mantle had been partly exhumed by detachment faulting and that the main strike-slip faults may themselves be reactivated and steepened lowangle detachments. The geodynamic driver for mantle exhumation along the detachment faults and strike-slip faulting in central Seram is very likely the same; we interpret the extreme extension to be the result of eastward slab rollback into the Banda Embayment as outlined by the latest plate reconstructions for Banda Arc evolution.

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