CENDERAWASIH BAY GEOLOGICAL SETTING AND ITS ASSOCIATION WITH BIRD’S HEAD TECTONIC EVOLUITON

• Main Author: CESSNA ADYAGHARIN, AILERON
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/13220
• Institution: Institut Teknologi Bandung

Researches on geology and evolution of Bird's Head area have been conducted for years by many authors. The lack of geological data to construct tectonic and evolution model of Cenderawasih Bay were due to a very small amount of exploration activities. The current models generally were assembled based on geological data in the adjacent area, which are the Papua mainland and small islands lies in the bay.<p>Cenderawasih Bay could be classified into a frontier basin. Two wells data were available. In 1973, Tesoro Indonesia drilled two wells, but then after that, there has been no drilling activity in the basin.Onshore of North Papua limited amount of seismic lines have been recorded only 1,380 km. There were no offshore seismic activity has been recorded until 2007. TGS NOPEC then shoots hundreds of kilometers new seismic lines and multibeams on this frontier basin. Multibeams was used to acquire maps of both backscatter and seafloor bathymetry.<p>This thesis will deduce new development model of Cendrawasih in the northern part of Papua. The geology of the bay will play an important role to explain the Bird's Head tectonic evolution. The new presented model generate mainly based on results of interpretations on acquired seismic lines, time structure map, 3D geological cross section, and palinspatic reconstructions.<p>Recent studies on plate movement indicate that the Indo-Australia continental plate is moving to the north, while the Pacific oceanic plate is moving to the southwest. The deformations from this oblique collision are recorded on the tectonic history of Bird's Head and New Guinea mainland.<p>Several major geological features that affected the tectonic history of Bird's Head form the boundaries of Cenderawasih Bay. The east-west trending Sorong-Yapen Fault Zone is on the center of the research area, the northern part is bounded by New Guinea Trench, to the east by Waipoga Through, to the south by the Weyland Overthrust, and last but not least the western margins are Lengguru Fold-Thrust-Belt, Ransiki Fault Zone, and Kemum High.<p>Seismic interpretations on 72 new 2D lines and bathymetry on the seafloor topography showed a rapid growth of geological structure and sedimentation development. Seismic interpretations were able to perform by using the principal of seismic stratigraphy. This was due to the lack of proper subsurface stratigraphical data.<p>Time structure map and 3D cross section showed the majority fault trends, geometry and topography of basinal area and high area. A NE-SW fault trending were interpreted related to the extensional deformation phase occurred in the research area. An E-W fault trending proofing the Sorong-Yapen Fault Zone activities. Compressional deformation is found on the southeastern part of Cenderawasih Bay in the offshore Waipoga Trough. This compression is a spectacular NE-SW trending thin-skinned fold-thrust-belt system which later on known as Waipoga Fold Thrust Belt. Palinspatic reconstruction will illustrate the geological structure construction and sedimentation on the interpreted seismic lines. This reconstruction is used to confirm the existing extensional or compressional deformation feature based on its fault.<p>Evidence from seismic interpretation in the resulted model suggests Bird's Head might be shifted and slightly moved in counter clockwise direction to the west. This movement is interpreted related to extensional event occurred in the. The extensional mechanism and the E-W left-lateral strike-slip fault occurred following the arc-continent collision, constructing the present specific geographical features of Cenderawasih Bay.<p>An appropriate stratigraphical data will provide more information on the basement underlying Cenderawasih Bay and the lithology above basement, therefore a further geological exploration is required, such as well drilling offshore of Cenderawasih Bay.