Samuel Melia and Robert Hall

Aims

This PhD project aims to integrate the results of previous studies undertaken by the SE Asia Research Group along the length of the Sorong Fault Zone. These comprise extensive onshore field-based projects and those based on offshore seismic and multibeam data from several parts of the region. The project aims to understand the Neogene evolution of the fault zone in the area from Sulawesi to New Guinea. This will be complemented by other studies that are planned or are in progress in Sulawesi and the Bird’s Head.

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Background

The Bird’s Head of New Guinea lies at the boundary between the Australian, Pacific, Philippine Sea and Molucca Sea plates. The shared boundaries of these plates are marked by an extensive series of strike-slip fault zones. The Sorong Fault zone is the largest of these fault zones, stretching from the Bird’s Head in West Papua to East Sulawesi. Along the fault zone are fragments of Australian continental crust, ophiolitic and arc crust from the Pacific and Philippine Sea plates, as well as continental and ophiolitic rocks from the Sundaland margin. The geology of the region indicates that arc-continent collision occurred between the Philippine Sea and Australian plates in the Early Miocene, as well as the collision of the Sula Spur with the Sundaland margin in Sulawesi. The Sorong Fault Zone developed after this period.

Several of our recent studies have shown that major structures previously interpreted either do not exist or have the opposite sense of displacement to previously proposed. A review and reinterpretation of all previous data is essential. The aim is to produce a new map of structures along the Sorong Fault Zone to identify their displacement and age, and produce a new tectonic synthesis. To achieve this, the project will use data from land investigations of islands around Halmahera, Bacan and Waigeo, the Banggai- Sula islands, Buru, Seram and Sulawesi, as well as offshore seismic and multibeam data (Banggai-Sula islands, Weda Bay Halmahera, the Seram Trough, and the offshore Sorong Fault from north of Misool to Salawati). We anticipate the fault would be mapped in 3D (where possible) and relevant software would be used to restore the deformation that took place along the fault zone.

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