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The Sorong Fault Zone Kinematics: The Evidence of Divergen and Horsetail Structure at NW Bird's Head and Salawati Basin, West Papua, Indonesia

Riadini, Putri; Sapiie, Benyamin
Exploration, APEC-Bunga Mas International Company, Jakarta, Indonesia.

The Sorong Fault Zone (SFZ) is an active left lateral fault system that active since the Late Miocene, confirmed by its activities during the deposition of the Late Miocene sequence. The SFZ is located in the northern margin of Papua, Indonesia, extended thousand kilometers from the Eastern part of the island to the Bird's Head region. Our new model indicates that SFZ moved the Bird's Head area, including Salawati Basin to the west, related to the movement of the Pacific Plate. The movement of SFZ involves rotation and translation that separates Salawati Basin from the Bird's Head region with basement high as the boundary of the basin.

More than 200 seismic lines have been interpreted along Seram, Misool, and Salawati offshores. These interpretations show the development of NE-SW trending listric and planar normal faulting at Western part of Misool Island and NE-SW trending flower structure at NW Bird's Head region. This faulting activity was interpreted as a result of SFZ activities, which cut Paleozoic through the Tertiary formations. The listric and planar normal fault in the Salawati Basin explains the block rotation mechanism that related to the Bird's Head movement to the west. The listric and normal fault is also related with the development of pull-apart basin and en echelon faulting that involves to the Salawati Basin forming. In addition, flower structures that observed at NW Bird's Head indicate the shortening effect of the SFZ activities. These flower structures is also interpreted as a part of restraining fault in the SFZ strike-slip system, whereas, the releasing fault is also showed as a package of NE-SW normal faulting. These releasing and restraining fault is related with the horsetail mechanism that also apart of SFZ strike-slip system.

New seismic interpretations combined with palinspatic reconstruction suggest that there are rotation and translation phase in relation to SFZ mechanism that develops the Salawati Basin. These deformations mechanism are active since the Late Miocene related to the collision between Pacific island arc complexes and passive margin of the NW Australian plate.


AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012