NSFGEO-NERC: Carbon concentration and variability in Earth’s mantle

What controls carbon concentration and variability in the Earth’s mantle is an important unanswered question. This project will address this question using small melt droplets in lavas. These melt droplets trap magma from the mantle before they travel through the crust and erupt at the Earth’s surface. The investigators will use samples from Iceland and several seafloor locations. The project will serve national interests through student training, public outreach, and building analytical capabilities. This project presents the first global-scale investigation of CO2 concentrations and carbon isotopes in melt inclusions from spreading ridge lavas, addressing two key questions: 1) What is the nature and origin of carbon heterogeneity in the convecting mantle? 2) How do crustal magmatic processes overprint the primary mantle C signal? Analytical work will leverage recent developments in multicollector secondary ion mass spectrometry for simultaneous δ13C and CO2 measurement in melt inclusions, using dual electron multipliers and extended integration times to reduce uncertainty. Supporting analyses will include electron microprobe, laser ablation inductively coupled plasma mass spectrometry, and secondary ion mass spectrometry to measure major, trace, volatile elements, respectively, enabling full contextual interpretation of δ13C data. Experimental data will help to quantify the δ13C fractionation between melt and vapor bubble within the melt. Results will place constraints on mantle carbon cycling and refine models of volatile transfer from the mantle to the oceans and atmosphere. The project will provide research opportunities and training for graduate and undergraduate students. It will build analytical capacity at US institutions. In addition, the investigators will develop two new exhibits at a museum for the public. This award was made possible through the NSF/GEO-UKRI/NERC lead agency opportunity. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2535974 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Gokce Ustunisik | Institution: South Dakota School of Mines and Technology, RAPID CITY, SD | Award Amount: $536,839 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2535974 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2535974.html