Project EARTH-17-MPS1: Structural and metamorphic evolution of the Zanskar Himalaya from crustal thickening through to melting and exhumation

Supervisors: Professor Mike Searle, Dr Dave Waters (Oxford), Dr Lars Hansen & Marc St-Onge (Geological Survey of Canada)

The Zanskar region of NW India is one of the few locations that reveals the early stages of crustal thickening in the Himalaya by stacking of major SW-verging fold nappes and prograde metamorphism of up to kyanite grade in the Greater Himalayan Sequence. Furthermore, these nappes are structurally underlain and overprinted by domes cored by higher-grade rocks and associated with abundant migmatite and crustal-melt granite, culminating in higher-T, lower-P metamorphism with sillimanite + K-feldspar and local cordierite. Such features are described elsewhere in terms of the channel-flow model.

This project aims to study the transition in space and time from crustal thickening to partial melting and exhumation in the Greater Himalayan Sequence through structural mapping, textural and petrological analysis of the melting process, metamorphic modelling of P–T–time paths, and accessory-mineral geochronology. These studies build on a legacy of previous work (see references below), but are also informed by insights gained more recently in other parts of the metamorphic Himalaya.

In practical terms, the project involves fieldwork along the Suru valley in Western Ladakh and the Zanskar valley followed up by detailed petrological, metamorphic, thermobarometric and U-Pb age dating in order to unravel the complex tectonic history of the Himalaya. Petrology, microanalysis and thermobarometry will be undertaken at Oxford, and U-Pb monazite and zircon dating will be carried out at at the Geological Survey of Canada in Ottawa. The student will be based at Oxford University, and will undertake two field seasons in the Zanskar Himalaya of NW India. The project is suitable for students with an interest in structure, metamorphism and granites who can think at all scales from micro- to regional tectonic scale. The student needs to be fit and able to work under Himalayan conditions, with trekking to altitudes up to 5-6 km, and camping out.

Further Reading:

Searle, M.P., Waters, D.J., Rex, D.C. & Wilson, R.N. 1992. Pressure, temperature and time constraints on Himalayan metamorphism from eastern Kashmir and western Zanskar. Journal of the Geological Society, London, 149, 753-773 doi:10.1144/gsjgs.149.5.0753

Searle, M.P., Waters, D.J., Dransfield, M.W., Stephenson, B.J., Walker, C.B., Walker, J.D. & Rex, D.C. 1999. Thermal and mechanical models for the structural and metamorphic evolution of the Zanskar High Himalaya. In: MacNiocaill, C. & Ryan, P.D. (Eds) Continental Tectonics. Geological Society, London Special Publication 164, 139-156.

Searle, M.P., Cottle, J.M., Streule, M.J. & Waters, D.J. 2010. Crustal melt granites and migmatites along the Himalaya: melt source, segregation, transport and granite emplacement mechanisms. Trans. Royal Soc. Edinburgh 100, 219-233.

Walker, J.D. et al. 1999. Metamorphism, melting and extension: Age constraints from the High Himalayan slab of Southeast Zanskar and Northwest Lahoul. Journal of Geology, 107, 473-495.

Walker, C.B., Searle, M.P. & Waters, D.J. 2001. An integrated tectonothermal model for the evolution of the High Himalaya in western Zanskar with constraints from thermobarometry and metamorphic modelling. Tectonics, 20, 810-833, 2000TC001249