Testing Hydrothermal Activity Changes Over Time Using Metal Records from the Pacific Ocean

Hydrothermal vents are an important source of dissolved metals to the deep ocean. Recent studies imply that changes in hydrothermal activity at mid-ocean ridges are linked with variations in sea level. The idea is that higher sea levels will increase pressure and reduce hydrothermal activity, while lower sea levels will have the opposite effect. This study will test the hypothesis linking sea level and hydrothermal activity by studying hydrothermal metal fluxes in sedimentary records at different ages in the southern Pacific. The project leverages existing sedimentary materials from NSF-funded repositories. These results will improve understanding of how seafloor processes influence ocean chemistry and the availability of metals that support marine life. The project will also provide training for students in analytical techniques and scientific research. Previous studies of sedimentary cores near several mid-ocean ridges indicate that hydrothermal metal fluxes were greater during the last deglaciation than the Last Glacial Maximum. Additionally, results from the southern East Pacific Rise indicate that fluxes of 230Th to ridge crest sediments were much higher than the water column production rate, driven by hydrothermal scavenging and lateral transport of 230Th from the ridge flanks. This study will test whether metal flux records are controlled by sea level or alternatively, by changes in oxidation rate linked to ocean ventilation and changes in ocean circulation. The focus will be on developing high-quality metal flux records along a transect spanning from 300 km to 2500 km west of the southern East Pacific Rise. Analyses include constructing foraminiferal d18O records, 14C dating and 3He-normalized sediment fluxes, and metal concentration records. The results could have broad implications for understanding the links between the fluid and solid earth. 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: 2538285 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: David Lund | Institution: University of Connecticut, STORRS, CT | Award Amount: $164,940 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2538285 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2538285.html