Geology Department Postgraduate Web Pages
Name: Brendan Hoare
Contact Details
Tel: +353 (0)1 896 1363
Fax: +353 (0)1 6711199
Email: hoareb@tcd.ie
Title of Project
Halogens in the West Greenland sub-continental lithospheric mantle
Project details
The volatile content of the lithospheric mantle largely reflects its initial depletion as a result of the differentiation of the mantle-crust system and has led to the overwhelming concentration of volatiles within the Earth’s surface reservoirs. Nonetheless, subsequent (re)enrichment by volatile-rich fluids and/or melts derived from subducted slabs and from the primordial volatile reservoir suggests that metasomatised lithospheric mantle remains a significant repository for volatile elements within the mantle. Volatiles therefore represent key tracers of volatile transport processes and storage within the Earth, whilst also indicating the presence and origins of mantle heterogeneities. The use of halogens (F, Cl, Br, I) as geochemical tracers has been limited by the accuracy and precision of instrumentation used in their study and a lack of understanding of their behaviour in the Earth system. With significant advances in both instrumentation and understanding within the last decade the use of halogens as key geochemical tracers to elucidate volatile transport processes and mantle heterogeneities is now both possible and key to the improvement of our understanding of the cycle of volatiles and heterogeneities within the Earth’s mantle.
The primary aim and ultimate goal of this Science Foundation Ireland project is to constrain the halogen volatile flux from the convecting mantle to the overlying sub-continental lithospheric mantle through the study of mantle-derived kimberlitic magma (preserved as melt inclusions) and also of volatile-free (olivine, diopside) and volatile-bearing (phlogopite) mantle minerals from the Pyramidefjeld kimberlite field, Southwest Greenland. The laboratory work will comprise; SEM (EDS, EMPA), FTIR, LA-ICP-MS at Trinity College Dublin and SIMS at the NordSIM facility of Stockholm, Sweden.
Name of supervisors
Dr Emma Tomlinson
Postgraduate personal details
I am originally from the United Kingdom and graduated from the University of Plymouth, with an MGeol (Master of Geology) with honours. My third year dissertation project comprised six weeks mapping in the Simano nappe of the Campolungo region, Switzerland for Geological Society of London accreditation. For my fourth year project garnet and clinopyroxene xenocrysts sampled from the Kaavi-Kuopio kimberlite province were analysed with SEM (EDS, EMPA) as well as LA-ICP-MS to ascertain the thermal structure of the sub-continental lithospheric mantle, whilst also providing a detailed lithological and geochemical reconstruction of the sub-continental lithosperic mantle, in an effort to evaluate diamond prospectivity within the region.
Project Start Date
September 2015
Funding
Science foundation Ireland
Publications
Dijkstra, A. Hoare, B. Cherepanova, Y. & Lehtonen, M. (2015). Fast automated mineral analysis of kimberlite xenocrysts for diamond exploration, Lahtojoki kimberlite, Finland. Poster at Goldschmidt, Prague.