Kopp, Christian (1998) Struktur und tektonische Mechanismen der Nord-Sulawesi Subduktionszone (Indonesien) : kombinierte Interpretation weitwinkel- und steilwinkelseismischer Daten. (PhD/ Doctoral thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 120 pp.

Text Diss_Kopp_C_1997.pdf - Reprinted Version Restricted to Registered users only Available under License German copyright act UrhG. Download (11MB) | Contact

Abstract

The Celebes Sea is an Eocene basin between Indonesia and the Philippines, located in the collision zone of three converging tectonic plates: the Pacific, the Indian-Australian and the Eurasian Plate. The tectonic processes of the Celebes Sea are still ambiguous as are for most of the numerous marginal basins and collision zones in this area. Due to the northward thrust of the Australian Plate, the Celebes Sea is subducting beneath the northern part of the Sulawesi island. Refraction seismic interpretations of the North-Sulawesi subduction zone provide insight to the subduction mechanisms, structure, and composition of the oceanic ernst in the Celebes Sea. Seismic wide-angle and multichannel-reflection data were recorded on three lines perpendicular to the strike of the North-Sulawesi subduction zone. The data processing and interpretation was improved by combining both datasets and the correlation is shown in joint illustrations. Due to the extent of the measurements and the complexity of the subsurface, the interpretation of the wide angle data is largely based upon traveltime information. In some parts of the research area dynamic modelling was also carried out, particularly for verification of strong shear wave amplitudes observed at some stations. Strang reflexions outline prominent block structures on all three reflection seismic lines. These structures were firstly interpreted as crustal splinters imbedded in the accretionary wedge, similar to those observed in the adjacent Sulu Sea. However, in the Celebes Sea this interpretation cannot be supported by increased refraction velocities. Here, the seismic velocities are relatively low even in deeper parts of the wedge. The Celebes Sea is underlain by normal oceanic crust, but beneath North-Sulawesi a crustal thickening from 7 km to about 12 km is observed on all profiles. An explanation for this thickening might be provided by thrusting or jolting of the ernst, induced by collision of the subducting Celebes Sea plate with a lithospheric slab dipping northward under Sulawesi. A hypothesis which is supported by active seismicity in the area.

Actions (login required)

View Item