Some of the greatest mountain belts on Earth, including the Himalayas, formed as a consequence of the collision between two continents. During such major tectonic upheavals, rocks are buried, deformed, transformed into new rock types or melted, before being transported back to the surface. How long this overall process takes, and whether the affected rocks record evidence of continuous or abrupt episodes of change, is unknown. For instance, processes such as the formation of granite melt were once considered to be ‘instantaneous’ on geological timescales, and occurred when fertile source rocks crossed a melting reaction at specific pressure-temperature conditions. However recent research in the Himalayas has shown that the large granite plutons that pepper the highest structural levels of the orogen may form via a series of pulsed melting events1, and that their source rocks may change over time2. As partially molten rocks are much weaker than non-molten rocks, their presence in the depths of the collision zone significantly affects how continental-collision mountain belts form3.
This project therefore aims to constrain the source, melting reactions, melting timescale and repeat-rate of melting pulses of a well-exposed transect through gneiss to migmatite to granite in the Garhwal region (Badrinath) of the Indian Himalaya. This valley transect exposes the entire granite-generation history from un-melted gneiss, up into migmatites, then the segregation of melt into channels and the transport of melt upwards to feed the pluton.
The samples will be dated using cutting edge laser-ablation split-stream4 and SHRIMP methods on zircon and monazite at Curtin University in Australia. The combination of isotopic (U-Pb, O, Hf) and trace element (rare earth) compositions allow mineral ages to be linked to geological process via detailed petrographic investigation and subtle trace element reaction “fingerprints”5. The development of novel trace element fingerprints for linking the crystallisation of the geochronology phases (zircon and monazite) to the crystallisation history of the major phases will form part of this project.
Samples will be collected during a field season to Badrinath and surrounding valleys in Year 1, and processed at the Open University (OU). Mineral major element chemistry data will be collected on the OU electron microprobe and mineral trace element chemical data will be collected on the OU laser-ablation ICP-MS system. At least one trip to the labs at Curtin University in Perth, Australia, will provide geochronological and supplementary trace element data including U-Pb, Hf isotope, O isotope and rare earth element data from the accessory minerals.
Training and Skills
NERC CENTA students are required to complete 45 days training throughout their PhD including a 10 day work placement. In the first year, students will be trained as a single cohort on environmental science, research methods and core skills. Throughout the PhD, training will progress from core skills sets to master classes specific to CENTA research themes.
Specific scientific training will include safe fieldwork planning, rock preparation (crushing, mineral separation/picking, thin-section making), data collection using a variety of cutting-edge geochemical instruments, and interpretation using a variety of chemical and statistical plotting methods.
The School of Environment, Earth and Ecosystem Sciences has a thriving postgraduate community. Online teaching opportunities including teaching on OU undergraduate modules and Massive Open Online Courses (MOOCs) are available via the OU Virtual Learning Environment.
Additionally, our students may gain excellent skills in science outreach by contributing travel experiences to platforms such as Traveling Geologist (http://www.travelinggeologist.com/), and Fieldwork Diaries (http://www.fieldworkdiaries.com/), or contributing to the CENTA student research blog (https://centaresearch.wordpress.com/).
Year 1: Initial induction, literature review and familiarisation with the OU sample collection. Fieldwork in India (3 weeks). Sample preparation, initial data collection. Laboratory trip to Perth (2 weeks)
Year 2: Interpretation of first data set. Presentation at national conference. Second laboratory trip to Perth (2 weeks). Work placement (2 weeks).
Year 3: Interpretation of second data set. Preparation of papers. Presentation at an international conference. Writing and submission of thesis.
Partners and collaboration (including CASE)
This project will involve training, supervision and lab work at Curtin University in Australia.
Students should have a strong background in hard rock geology and enthusiasm for adventurous fieldwork and detailed labwork. Experience of mountainous/remote fieldwork and love of igneous or metamorphic petrology is highly desirable. The successful student will join a well-established team researching Dynamic Earth processes at the Open University and Curtin University.
For further information please contact Clare Warren using the details above.
Applications should include:
- a cover letter outlining why the project is of interest and how their skills match those required,
- an academic CV containing contact details of three academic references
- a CENTA application form, downloadable from: http://www.centa.org.uk/media/1202/centa-studentship-application-form.docx
- and an Open University application form, downloadable from: http://www.open.ac.uk/students/research/sites/www.open.ac.uk.students.research/files/documents/Application%20form.docx
Applications should be sent to
by 5 pm on Monday 22nd January 2018