Provenance of Banda Arc sandstones: tectonic models and Mesozoic palaeogeography

Sebastian Zimmermann, completed PhD

This project aims to use sandstones from the outer arc islands to develop an understanding of sediment sources and palaeogeography, and test tectonic hypotheses for Banda Arc development.

The Banda Arc is a 1,000km long, 180-degree curve in eastern Indonesia that comprises young oceanic crust, enclosed by a volcanic inner arc, an outer arc of islands and a trough parallel to the Australian continental margin. It is a region of active hydrocarbon exploration and recent discoveries. Sandstones from the many islands around the arc contain important information relevant to its tectonic evolution, in particular the nature and age of its basement, and location of blocks rifted away in the Jurassic, as well as information about the Mesozoic palaeogeography of northwest Australia and provenance of sediments.

banda_arc_SRTM_DEM IMW-Boat,-Seram2

The project will build on several recent provenance studies by the SE Asia Research Group in the region, which are providing an understanding of source lithologies, basement ages, distribution of tectonic blocks, and patterns of sediment movement, based particularly on heavy mineral and zircon studies. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb dating of zircons is a relatively quick and cost effective way of dating large numbers of detrital grains. The analyses provide an age distribution for individual samples; significant age peaks can then be compared to the characteristic peaks of potential source lithologies and/or regions and the growing reference database of age signatures from around the region. There are few zircon data from the Banda Arc. Our pilot study of sandstone samples from the northern Banda Arc recovered many zircons and U-Pb LA-ICP-MS dating of zircons identified several distinctive age peaks.