Investigating the Mt. Kinabalu pluton, northern Borneo: testing models for emplacement and exhumation
Michael Cottam, Robert Hall, Richard Armstrong, Marnie Foster, Mathew Thirwall
Mount Kinabalu is a highly unusual mountain. Rising to over 4000m, it is the highest mountain between the Himalaya and New Guinea, towering over the nearby peaks of the Crocker Ranges, northern Borneo, around 2 km below. Its position at the end of a mountain range and its non-volcanic nature – the mountain comprises various granitic lithologies – are both extremely uncommon for such a high peak.
Despite its unusual character, the origin, crystallisation age and subsequent uplift history of the Mt. Kinabalu pluton remain poorly constrained. Situated away from active subduction, the origin of Mt. Kinabalu’s plutonism is unclear. Several models have been proposed including links to southerly subduction of the proto-South China Sea beneath Borneo. Previous studies by the SEARG revealed fluid-absent melting indicative of melt generation during post-subduction collisional thickening. New data suggest that Mt. Kinabalu is currently being rapidly exhumed.
The key to further understanding the intrusion and exhumation mechanisms of the Mount Kinabalu Pluton lies in unravelling the crystallisation of the pluton and it’s subsequent Cenozoic thermal history. This project focuses on investigations of the pluton’s crystallisation history using geochronological methods, complementing the ongoing low-temperature thermochronological study of Christian Sperber. The project has explored the nature of the pluton’s crystallization history using several geochronological and thermochronological tools:
- SIMS dating of zircons (SHRIMP II)
- Rb/Sr analyses of several phases
- 40Ar-39Ar dating of biotite
Cottam, M.A. Hall, R., Sperber, C. & Armstrong, R. 2010. Pulsed emplacement of the Mount Kinabalu Granite, North Borneo. Journal of the Geological Society of London, 167, 49-60. PDF
Cottam, M.A., Hall, R., Sperber, C., Kohn, B.P., Forster, M.A. & Batt, G.E. 2013. Neogene rock uplift and erosion in Northern Borneo: evidence from the Kinabalu granite, Mount Kinabalu. Journal of the Geological Society of London, (in press).