Project title: Deciphering the signature of fluid/rock reaction in the lower oceanic crust: The Oman ophiolite analogue
Director of Studies: Dr Michelle Harris
2nd Supervisor: Professor Antony Morris
Applications are invited for a three-year PhD studentship. The studentship will start on 1 October 2018.
Recent studies have highlighted the requirement for hydrothermal circulation at mid ocean ridges to extend into the lower crust1. How deep these fluids penetrate, how much fluid reaches these depths and what are the fluid pathways are critical questions to answer in order to test the two end member models (gabbro glacier and multiple sills2) for the accretion of the lower crust. Hydrothermal circulation is recorded by fluid/rock reactions that result in the formation of secondary minerals; rocks from the ocean crust therefore provide a record of this key Earth process3. Field studies of ophiolites have been critical for the development of our understanding of the ocean crust, but have been limited to samples exposed at the surface. The ICDP Oman Drilling Project (www.omandrilling.ac.uk) has successfully recovered 1200m of cores from the lower crust of the Oman ophiolite, providing a unique set of cores to test these end member models4. This project will combine high-resolution quantitative core logging along with novel imaging methods (xCT and imaging spectroscopy) with the outcrop scale context, providing an unrivalled opportunity to study the formation of the ocean crust.
Project aims: (1) to determine the characteristics of the lower crustal hydrothermal system both in terms of the fluid and rock, and (2) to test the end member accretion models. The student will be trained in and apply high-resolution core logging, petrology (optical, SEM) and geochemical analysis to a suite of rocks and secondary minerals from the Oman Drilling Project cores.
1 Harris et al., 2017 EPSL
2 Summary in: Maclennan et al., 2004 G-cubed
3 Kelemen et al., 2014 https://tinyurl.com/jfouoy6