This project investigates the characteristics of the “Australian” basement rocks of the Bird’s Head. This work involves a combination of field studies with detailed petrological, geochemical and geochronological analyses of Silurian-Devonian metasediments and Permo-Triassic granitoids to better understand the rocks that underlie the majority of the Bird’s Head. Neither the age of the sedimentary protolith, nor the timing of at least two metamorphic events are well defined. Similarly, field observations suggest that the Bird’s Head experienced substantial and rapid uplift since the Pleistocene, but supporting data is sparse and the timing and rate of uplift are still to be quantified. Detailed descriptions of the regional basement geology and determining the timing of the tectono-thermal events will shed new light on potential sediment sources of the Cenozoic basin fill. The timing of uplift is a particularly crucial question, as this has implications for our understanding of the development of nearby basins.
Most of what is known about the geology of the Bird’s Head is based on a joint mapping programme by Indonesian and Australian government geologists in the 1970s and 1980s. However, their account of the metamorphic and igneous rocks found throughout the area remains fragmentary and the ages that were reported have not been substantiated using modern analytical techniques (e.g. LA-ICP-MS and SHRIMP) to determine precise and accurate U-Pb ages or (U-Th)/He cooling rates. This project focuses on the Kemum Formation and Permo-Triassic intrusions which intrude the former. These rocks have been targeted because the Kemum Formation and the granitoids contain minerals that record information about the timing of thermal events (metamorphism, melting and uplift).