EAPSI: Development of paired uranium-thorium and radiocarbon ocean ventilation records using deep-sea corals

Schoemann Mackenzie E, Bryan TX

Investigators

Abstract

The ecology and biology of deep-sea coral ecosystems has seen increased research efforts in part because of human-induced impacts, including fishing activities. The importance of conservation efforts of deep-sea corals has amplified due to increased awareness of deep-sea corals as habitat-forming organisms for commercial and noncommercial fish species, their extremely long lifespans, and their potential as a climate archive. Developing independent means of determining the life-span and growth rate of deep-sea corals is important to assess their vulnerability and recovery rates from natural and human-induced disturbances. Equally important is the development of high-resolution age models of deep-sea coral archives. This project aims to examine the paleo-ecology of deep-sea corals by developing proxies in both the proteinaceous and carbonate skeletons of deep-sea corals in collaboration with Dr. Steward Fallon at the Australia National University in Canberra, Australia. Access to the laboratory, equipment, and dating methods provided at ANU, will create an opportunity to expand knowledge and understanding of deep-sea corals. Development of paleoceanographic proxy measurements in deep-sea corals has moved beyond the range of potential promise in terms of reconstructing ocean ventilation rates. Records of ocean ventilation are used to determine how ocean chemistry has changed throughout geologic time, helping predict future climate change. This project will apply a novel uranium-thorium (U/Th) dating method paired with radiocarbon dates to develop age and growth rate records of black corals, Leiopathes sp. and cup corals, Desmophyllum sp. Pairing independent chronometers, such as U/Th dating with radiocarbon dating, allows for the reconstruction of ocean ventilation rates dating back to the Last Glacial Maximum (~20,000 years). The project will take a multiple proxy approach; pairing U/Th, radiocarbon, and neodymium isotopic measurement to reconstruct changes in surface, intermediate, and deep-water circulation patterns. This NSF EAPSI award is funded in collaboration with the Australian Academy of Science.