Adopted ReCoRD Proposals

Proposal numberReC23-01
Proposal titleTracing Intermediate Water Current Changes and Sea Ice Expansion in the Indian Ocean
Lead ProponentJunichiro Kuroda, University of Tokyo
Scientific ObjectivesWithin the proposed ReCoRD, we aim to understand the effect of changing climatic conditions during the “near-future warm period analogs” such as the Miocene Climatic Optimum (MCO), and subsequent cooling during the Middle and Late Miocene and Pliocene had on intermediate water formation and circulation. Model studies indicate that climatic changes lead to a positional shift of the westerlies, related to the expansion and contraction of sea ice around Antarctica. These changes further modulated intermediate water circulation and nutrient transport in the global oceans (see Laufkö tter, C. & Gruber, N., 2018; Science 359, 1103–1104).
Based on this hypothesis, we aim to identify and correlate evidence for intermediate water current changes and potential sea ice expansion in the Neogene by re- investigating key Ocean Drilling Project (ODP) Sites in the wider Indian Ocean. Our strategic sampling plan involves a transect through key features of Indian Ocean water masses targeting ODP Sites 707 and 752, as well as DSDP Site 266.
The objectives are, therefore:
1) Analyze Site 707 and 752 to define the sedimentological changes related to the
hypothesized reorganization of intermediate water circulation.
2) Provide new digital core archives which can be directly correlated to existing visual core descriptions to better quantify current winnowing or ice-rafted debris at the target Sites.
3) Targeted sampling of the study sites for subsequent laboratory-based studies to better define intermediate water changes that provide information regarding the origin and nutrient load of the water masses interacting with the sediment at each Site.
Proposed target cores115-707A, 1H – 15H
121-752A, 1H – 10H
28-266*, 1R – 22R
Sample request period~ June 13, 2023
Sampling party implementation periodApproximately two weeks from late August to mid-September 2023
Link to the proposalReC-001 Proposal