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James Crosby

James Crosby

Research Student 2017-2021

Geochemistry

Petrology

Mantle Xenoliths

Noble Gas Isotopes

N310
Office Phone: +44 (0) 1223 768357

Biography:

2016-2017 MSc Geochemistry, University of St Andrews

A taught masters degree delivering postgraduate-level knowledge and skills training in modern geochemical methods, involving field work, hands-on laboratory training, and experience with state-of-the-art equipment. A broad and rigorous course which provided preparation for pursuing a PhD, by incorporating a lab-based research dissertation. The lab-based research dissertation was done with Dr Sami Mikhail (University of St Andrews) and Prof Fin Stuart (SUERC) analysing polycrystalline diamondites for noble gas and volatile element isotopes to understand geodynamic factors influencing their formation. 

2013-2016 BSc (Hons) Geochemistry, University of Manchester

A fully accredited degree from the Geological Society of London allowing a specialized advanced understanding of geological and geochemical systems applied to research and industrial aspects. This degree combines academic, analytical and fieldwork aspects of learning with lecture, laboratory and field-based examinations.

Research Interests

Petrology and Geochemistry of Mantle Xenoliths

The project involves the novel analysis of volatile elements and noble gas isotopic ratios in both nominally volatile-free minerals (apatite, clinopyroxene, olivine) and volatile phases (phlogopite, amphibole) present in mantle xenoliths in order to constrain the volatile flux in the mantle. New analyses of Cl, F, H and C together with 3He/4He and 20Ne/22Ne for samples from a variety of tectonic settings to place important constraints on the nature and extent of volatile flux from subducting slabs and the convecting mantle to the overlying lithosphere.

This analysis is important because the present-day volatile content of the lithospheric mantle results from potentially billions of years of metasomatic enrichment but a key outstanding issue concerns the relative input of volatiles ‘leaking’ more or less continuously from the MORB source or downgoing slabs, compared with episodic fluxes of primordial volatiles from the deep mantle transported by plumes. Constraints on these fluxes are vital to understanding which branches of Earth’s chemical cycle are losing volatiles to long-term storage in the lithosphere. There is compelling evidence that a substantial volatile flux into the lithospheric mantle occurs more or less contemporaneously with mantle plume activity. More continuous metasomatism may be linked to alkali-carbonate fluids released from downgoing slabs in the convecting mantle.

This PhD is part of the University of Cambridge Earth System Science NERC Doctoral Training Partnership with the title "The source and flux of volatiles in Earth's lithospheric mantle".

Keywords

Petrology ; Geochemistry ; Mineralogy

Topics

  • Mantle petrology
  • Volatile geochemical cycling
  • Mantle xenoliths

Collaborators outside this directory

Key Publications

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