Geochemistry of acid volcanoes: Sunda Arc and Sulawesi
Scott Dempsey – completed PhD project
This project aims to investigate relationships between magmatic rocks from the Sunda Arc and Sulawesi in order to examine the nature, age and origin of unseen basement rocks within the region. Samples to be collected from the Sunda Arc (Sumatra, Java, Bali, Lombok) and Sulawesi, will be investigated using trace element, radiogenic isotope (Sr, Nd, Pb, Hf) ratios and stable (O) isotope analyses.
Magmatism provides a valuable probe into several aspects of an area’s tectonic evolution. The composition of magma is an integrated history of the source reservoir, the melting conditions that affected this source, and the nature of any crustal rocks with which the melt interacted. By interrogating the geochemistry of magma one can determine affinities between sources of different magmatic events and their relationships to crustal blocks through which they migrated. Acidic rocks are particularly useful because their melts tend to have long residence times in the crust, and are therefore most likely to interact with the crust and acquire a geochemical record of its nature.
The project will build on previous studies by Handley (2006, 2007) at Durham and Smyth et al. (2007) at Royal Holloway, who used geochemical and provenance approaches respectively to identify the character of crust beneath Java. This approach will be developed to determine how widespread ancient fragments may be within the Sunda basement (Java, Bali, Sulawesi, and possibly Lombok and Sumatra).