Lower plate structure and upper plate deformational segmentation at the Sunda-Banda arc transition, Indonesia.

Planert, Lars, Kopp, Heidrun , Lueschen, E., Mueller, C., Flueh, E. R., Shulgin, Alexey, Djajadihardja, Y. and Krabbenhöft, Anne (2010) Lower plate structure and upper plate deformational segmentation at the Sunda-Banda arc transition, Indonesia. Open Access Journal of Geophysical Research: Oceans, 115 (B8). B08107. DOI 10.1029/2009JB006713.

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The Sunda‐Banda arc transition at the eastern termination of the Sunda margin (Indonesia) represents a unique natural laboratory to study the effects of lower plate variability on upper plate deformational segmentation. Neighboring margin segments display a high degree of structural diversity of the incoming plate (transition from an oceanic to a continental lower plate, presence/absence of an oceanic plateau, variability of subducting seafloor morphology) as well as a wide range of corresponding fore‐arc structures, including a large sedimentary basin and an accretionary prism/outer arc high of variable size and shape. Here, we present results of a combined analysis of seismic wide‐angle refraction, multichannel streamer and gravity data recorded in two trench normal corridors located offshore the islands of Lombok (116°E) and Sumba (119°E). On the incoming plate, the results reveal a 8.6–9.0 km thick oceanic crust, which is progressively faulted and altered when approaching the trench, where upper mantle velocities are reduced to ∼7.5 km/s. The outer arc high, located between the trench and the fore‐arc basin, is characterized by sedimentary‐type velocities (Vp < 5.5 km/s) down to the top of the subducting slab (∼13 km depth). The oceanic slab can be traced over 70–100 km distance beneath the fore arc. A shallow serpentinized mantle wedge at ∼16 km depth offshore Lombok is absent offshore Sumba, where our models reveal the transition to the collisional regime farther to the east and to the Sumba block in the north. Our results allow a detailed view into the complex structure of both the deeper and shallower portions of the eastern Sunda margin.

Document Type: Article
Keywords: Geodynamics; Sunda Banda margin, oceanic crust, outer arc high, fore-arc basin, Lombok Basin, mantle serpentinization
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Refereed: Yes
Open Access Journal?: No
Publisher: AGU (American Geophysical Union)
Projects: Future Ocean, SINDBAD
Date Deposited: 06 Sep 2010 07:39
Last Modified: 27 Feb 2018 10:01
URI: https://oceanrep.geomar.de/id/eprint/8854

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