Exhumation and extension in North and East Sulawesi

Alfend Rudyawan and Eldert Advokaat, completed project

This project will examine the relationships between exhumation of basement rocks in Sulawesi, Indonesia, extension and subsidence in offshore basins, and regional tectonics.

Sulawesi lies in the zone of the convergence of the Eurasian, Indo-Australian and Philippine Sea plates. The island has long been interpreted as the result of collision and contraction in this convergent zone but new land and offshore observations challenge this interpretation and suggest a much more important role for extension, which continues at the present day, linked to subduction rollback. New seismic and multibeam data offshore indicate rapid subsidence whereas nearby on land there are newly identified metamorphic core complexes interpreted from shuttle radar imagery. The uplift on land and subsidence offshore appear to be contemporaneous and are probably linked. GPS observations indicate rapid movements of the upper crust, and there is a complex pattern of seismicity in the region.


The aim of the project is to identify the cause and timing of Neogene deformation and tectonic events. It will be conducted in parallel with a second PhD studentship awarded to an Indonesian student. The two research students will work together in the field and their projects will be complementary. Both projects will interpret structures on land and offshore. Field work will be based on interpretation of SRTM and ASTER imagery, and existing geological maps. New fieldwork will be undertaken in the north and east arms to map and date structures, determine the age and rates of young exhumation, and identify the nature of faulting and age of fault movements. The projects will use and interpret newly acquired multibeam imagery of the seafloor and 2D seismic lines between and around the north and east arms of Sulawesi.