Evolution of the Sorong Fault Zone, Northeast Indonesia

CHARLTON, TIM R., Plano, TX

The Sorong fault zone (SFZ) of northeast Indonesia is a broad zone of inferred left-lateral shear at the triple junction of the Indo-Australian, Eurasian, and Pacific plates. It is widely believed that fragments of the northern Australian continental margin in New Guinea are being detached and translated westward in this shear zone until they collide with the eastern margin of Eurasia (Sundaland) in the region of Sulawesi Island. However, the details of terrane translation, amalgamation, and docking remain poorly documented. In particular, the timing of events is very poorly constrained, with estimates for the commencement of the SFZ ranging from early Miocene or older to Pleistocene.

Recent investigations of the SFZ and the adjacent regions of Sulawesi and Irian Jaya (Indonesian New Guinea), including new fieldwork in several of the SFZ island-terranes (Waigeo, Halmahera, Bacan, Obi, and Sula), suggest a less mobilist interpretation of the region than many previous reconstructions. In general, the closest interisland geological correlations are between the geographically closest islands (e.g. Banggai-Sula-southern Obi; northern Obi-Bacan; West Halmahera-East Halmahera-Waigeo; Misool-Buru-Seram). This would seem to favor rather conservative reconstructions, and a new interpretation of the region based on this tenet is proposed. Although arc-continent collision commenced in New Guinea during the mid-Oligocene and only slightly later in Sulawesi, the SFZ did not begi to develop in its present form before the late Miocene.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)