ABSTRACT: Tectonics of the Palau-Halmahera-Waigeo Triangle, Western Pacific

John Milsom, Gary Nichols

The Philippine Trench, the New Guinea Trench, and the Marianas-Yap-Palau trench system converge in the region immediately to the north of the Bird's Head peninsula of Western New Guinea. New Guinea itself represents the active northern margin of the Australian continent and the Indo-Australian plate, while the complex region west of the Philippine Trench may be regarded as part of the active margin of Eurasia. Remnants of Paleogene and older arc systems make up the north coast ranges of New Guinea, eastern Halmahera, and Waigeo Island. The Caroline Sea, the Philippine Sea, and the Ayu basin are all underlain by oceanic crust that is younger than the crust of the main Pacific Plate further to the east. Plate motions in this area have obviously been extremely complex and ye evidence of current subduction is very limited. Tectonic synthesis is hampered by lack of data, but recent long-range sidescan sonar swathes, obtained with other geophysical and bathymetric data in the course of cruise CD30 of the RRS Charles Darwin, taken together with information now available from the adjacent island groups and from previous surveys, allow constraints to be placed on past plate motions and suggest explanations for the presence in the area of a number of quasi-oceanic plateaux and linear ridges.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990