Palawan Island, Philippines

Age, origin and thermal history of the Capoas intrusion, Palawan

Mike Cottam and Marnie Foster

This project aims to further understand Palawan’s tectonic history by investigating the age, origin and thermal history of the granitic Capoas intrusion in northern Palawan. The mineralogy of the Capoas intrusion provides a rare opportunity to date a single geological unit using a range of complementary geochronological and thermochronological techniques, and to develop a detailed thermal history representative of northern Palawan.

Google Earth DEM and geological map overlay of the Capoas region, Northern Palawan.

Photo of Mount Capoas, Northern Palawan

Key questions include:

What is the age and origin of the Capoas intrusion?
- Can the previously proposed Middle Miocene age be confirmed?
- Was the intrusion emplaced in a single event? Or does it reflect multiple, possibly pulsed, intrusion?
- What tectonic processes does the intrusion represent?
What can the thermal history of the Capoas intrusion reveal about the Neogene tectonic history of the region?
- Did Palawan experience significant exhumation in the Late Miocene and Pliocene, as seen in northern Borneo?
- Did Palawan form — along with northern Borneo — a part of large emergent area in the Late Miocene and Pliocene?
- Does the Capoas intrusion record significant extension within the region in the Late Miocene and Pliocene?

This project aims to apply a full suite of geochronological and thermochronological techniques to samples collected from the Capoas intrusion. Techniques applied will include:

U-Pb SIMS (Secondary Ionisation Mass Spectrometry) dating of zircon
40Ar/39Ar dating of white mica, biotite mica and possibly K-feldspar
(U-Th)/He dating of zircon and apatite

Recent Papers –

Max Webb et al., 2020. Isotopic mapping reveals the location of crustal fragments along a long-lived convergent plate boundary. Lithos.

https://doi.org/10.1016/j.lithos.2020.105687

Max Webb et al., 2020. The history of Cenozoic magmatism and collision in NW New Guinea – New insights into the tectonic evolution of the northernmost margin of the Australian Plate. Gondwana Research.

https://doi.org/10.1016/j.gr.2019.12.010

Amy Gough et al., 2020. Mid-Cenozoic fluvio-deltaic to marine environments of the Salin Sub-basin, Central Myanmar. Journal of Asian Earth Sciences.

https://doi.org/10.1016/j.jseaes.2019.104143

Recent News –

Amy Gough and Max Webb attended the Restech 2.0 Virtual Reservoir Conference. Amy Gough presented new SEARG research on the pitfalls of light mineral studies for sedimentary provenance in tropical climates.

Amy Gough was awarded an honorary research fellowship of the British Geological Survey and continues to foster collaborative relationships between SEARG and the BGS.