Slumping, sliding and the occurrence of acoustic voids in recent and subrecent sediments of the Savu forearc Basin (Indonesia)
van Weering, T.C.E.; Kusnida, D.; Tjokrosapoetro, S.; Lubis, S.; Kridoharto, P. (1989). Slumping, sliding and the occurrence of acoustic voids in recent and subrecent sediments of the Savu forearc Basin (Indonesia). Neth. J. Sea Res. 24(4): 415-430
In: Netherlands Journal of Sea Research. Netherlands Institute for Sea Research (NIOZ): Groningen; Den Burg. ISSN 0077-7579; e-ISSN 1873-1406, meer
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| Auteurs | | Top |
- van Weering, T.C.E., meer
- Kusnida, D.
- Tjokrosapoetro, S.
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| Abstract |
High resolution seismic and acoustic profiles were acquired during legs G2 and G6 of the Snellius-II Expedition in the Savu Basin. They show that acoustic voids occur widespread in this basin. The acoustic voids are found along the periphery of an area of over 3900 km² that has been strongly influenced by recent and/or subrecent mass movements. The acoustic voids occur as bright spots with a transparent acoustic character. They incidentally have a relief of up to 100 m above the surrounding seafloor. Horizontal dimensions are up to 3 km width. Within the voids bedding planes locally are well preserved and continuous, although the bedding planes may appear weaker and sometimes are completely absent. Methane formation because of rapid sedimentation of organic-rich sediment may have caused the voids. However, the characteristic acoustic masking effect occurring normally on top of such deposits has nowhere been found in the Savu Basin and the distribution of the voids does not support this hypothesis. Thus, we suggest that the acoustic voids are formed as a result of local expulsion of pore-waters, caused by sediment mass movements down the uplifted ridge between the Islands of Sumba and Savu/Roti, rather than by methane formation. Southwest of Timor shale diapirism, probably associated with thrust tectonics is suggested as agent for the formation of the voids. |
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