- Two field seasons in Deccan Traps, India logging and studying basaltic pahoehoe flows, their volcanic features and collecting samples
- Study the volcanic stratigraphy and flow relationships to develop a method using GIS to assess the emplacement durations of basaltic flows in large igneous provinces.
- Geochemical analysis of collected basaltic samples to aid stratigraphic correlations as well as quantifying their compositions and gas content for assessment of environmental impacts.
- Opportunity to accompany Dr Passey as his field assistant to the Ethiopian Traps as part of an industry placement and to widen experience in LIP volcanostratigraphy.
The Deccan Large Igneous Province (LIP) is associated with the Cretaceous-Paleogene Boundary (KPB) mass extinction event at 66Ma. However, this is not the only environmental crisis it is linked to. Petersen et al. 2016 show a regional warming and extinction event in Antarctica and Hull et al. 2020 constrain an implied major volcanic outgassing event. Both are ~250,000 years before the KPB. Such events suggest a sustained period of large volume volcanic activity. The Thakurvadi Formation in the Kalsubai Sub-group, Deccan, is a prime candidate for this.
The Thakurvadi Fm (Fig. 1a) is up to 600m thick and covers ~80,000km2, although its full extent is not known. The flows of the Thakurvadi form a thick, competent part of the Western Ghats Escarpment (WGE; Fig. 1a), with very few weathering horizons. This and the welded appearance of the lobes indicate rapid emplacement with little pause between eruptions. The continuous emission of gasses could have caused the environmental effect ~250,000 years before the KPB.
This project will involve two field seasons. The first will involve logging and mapping of the Thakurvadi in the WGE to recreate the 3D volcanic architecture and volcanostratigraphy of the welded lobes and establish their size and spatial relationships. Cumulatively, this may allow an estimate of the time taken to emplace the entire Thakurvadi Fm. Samples will be collected and analysed using the electron microprobe and SIMS analyses of hosted melt inclusions (pockets of magma trapped in minerals) will enable their sulfur, chlorine, fluorine, carbon and water concentrations to be quantified.
The second field season will establish whether the style of the Thakurvadi continues further east and will help confirm its association with the pre-KPB environmental perturbation. Geochemical analyses (using a combination of electron microprobe, XRF and ICP-MS techniques), particularly incompatible trace elements, will be used to confirm the presence of Thakurvadi flows by comparing their chemistry with the known chemostratigraphy. The identification and interpolation of formation boundaries will help constrain the volume of the Thakurvadi Formation.
Basic modelling will be undertaken to link the new gas emissions data to the perturbations seen 250,000 years before the KPB.
HostThe Open University
- Dynamic Earth
- Dr Anne Jay, Open University
- Dr Frances Jenner, Open University
- Dr Simon Passey, CASP
- Prof. Hazel Rymer
- Verifying the rapid emplacement of the Thakurvadi by mapping and assessing the lateral continuity of flows and weathering horizons.
- Using the equation from Hon et al 1994 to estimate the emplacement duration of individual and cumulative lava flows of the Thakurvadi Fm in the WGE.
- Establish extent and style of the Thakurvadi Fm away from WGE. Detailing logging and collect samples for whole-rock geochemistry to establish stratigraphic correlations. Determine volume estimates for the formation.
- Analyse whole rocks and melt inclusions using XRF, electron microprobe, SIMS and ICP-MS techniques. Assess the petrogenesis of the Thakurvadi magmas, from melting of the mantle source, crystallisation in the crust and during eruption. These analyses will be used to answer questions such as ‘why are the flows so voluminous’.
- Model the environmental effect of the Thakurvadi Fm using formation volume, estimated emplacement period and gas emissions and assess likelihood of relationship to the pre-KPB events.
Training and skills
Training will be given in:
- Logging basaltic lava flows.
- Basic surveying techniques.
- Using GIS software for spatial modelling
- Geochemical analytical techniques and data handling skills.
- Planning and running a successful field trip.
- The successful candidate will be encouraged to attend relevant conferences. They will also be supported in applying for a placement, and to take part in career-enhancing opportunities such as teaching, science communication and understanding policy.
Partners and collaboration
The project will collaborate with Prof. Stephen Self (University of Berkley, California) a world leading expert in the emplacement of LIPs, who will be present for at least part of the field trips. To provide expertise in India: Dr Gauri Dole (Savitribai Phule Pune University), Dr Vivek Kale at (Advanced Center for Water Resources Development and Management, Pune; India), both Deccan volcanostratigraphical experts and Dr Makarand Bodas the Deccan LIP lead at the Geological Survey of India. A placement at CASP and field trip to Ethiopia as field assistant to co-supervisor Dr Simon Passey.
Applications should include:
- an academic CV containing contact details of three academic references
- a CENTA application form
- and an Open University application form, downloadable from:
Applications should be sent to STEM-EEES-PHD@open.ac.uk by 11.01.2021
Literature review on the Deccan Traps and Thakurvadi Fm in particular. Collate information on its current extent and exposure. First field trip to India in January/February including detailed fieldwork training with supervisors. Analyse data from fieldwork using GIS. Start analyses on glass inclusions.
Second Field trip to India. Attend VMSG conference. Analyse data from fieldwork including geochemistry, and write up manuscript on Emplacement of Thakurvadi Fm. Use GIS to estimate volume of the Thakurvadi Fm.
Finish interpretation, assess impact of Thakurvadi Fm on Pre-KPB environment, prepare thesis and further manuscripts. Presentation at an international conference. Possibly suspend PhD studies for several months to complete internship.
Hull, P. M., Bornemann, A., Penman, D. E., Henehan, M. J., Norris, R. D., Wilson, P. A., Blum, P., Alegret, L., Batenburg, S. J., Bown, P. R., Bralower, T. J., Cournede, C., Deutsch, A., Donner, B., Friedrich, O., Jehle, S., Kim, H., Kroon, D., Lippert, P. C., … Zachos, J. C. (2020). On impact and volcanism across the Cretaceous-Paleogene boundary. Science, 367(6475), 266–272. https://doi.org/10.1126/science.aay5055
Jay, A. E., Mac Niocaill, C., Widdowson, M., Self, S., & Turner, W. (2009). New palaeomagnetic data from the Mahabaleshwar Plateau, Deccan Flood Basalt Province, India: implications for the volcanostratigraphic architecture of continental flood basalt provinces. Journal of the Geological Society, 166, 13–24. https://doi.org/10.1144/0016-76492007-150
Jay, A. E., Marsh, J. S., Fluteau, F., & Courtillot, V. (2018). Emplacement of inflated Pāhoehoe flows in the Naude’s Nek Pass, Lesotho remnant, Karoo continental flood basalt province: use of flow-lobe tumuli in understanding flood basalt emplacement. Bulletin of Volcanology, 80(2). https://doi.org/10.1007/s00445-017-1189-6
Kale, V. S., Dole, G., Shandilya, P., & Pande, K. (2019). Stratigraphy and correlations in Deccan Volcanic Province, India: Quo vadis? Geological Society of America Bulletin.
Petersen, S. V., Dutton, A., & Lohmann, K. C. (2016). End-Cretaceous extinction in Antarctica linked to both Deccan volcanism and meteorite impact via climate change. Nature Communications, 7, 9. https://doi.org/10.1038/ncomms12079
If Covid-19 prevents overseas fieldwork the project could study the geochemical evolution of the Thakurvadi Formation by analysing pre-existing geochemical data, new geochemical and petrographically data from existing rock samples. Or a GIS could be built to analyse pre-existing data of the Deccan. If UK field work is possible, the project could focus on the physical volcanology of the extrusives of the North Atlantic Igneous Province as a comparison with the Deccan, possibly using drones to create 3D data sets. We will work with the successful applicant to build a project that interests them.