Adopted ReCoRD Proposals

Implementation Number: ReC23-02

Proposal numberReC-003
Proposal titleUnderstanding the Formation Process and Physical Property Distribution of the Upper Prism in the Japan Trench
Lead ProponentNana Kamiya, Kyoto University
Scientific ObjectivesThe Japan Trench is an erosional subduction zone, where the shallow part of the plate boundary fault was thought to have neither strain accumulation nor slip propagation due to the non-asperity nature of the shallow plate boundary. However, the 2011 off the Pacific coast of Tohoku earthquake demonstrated that the shallow part has the potential to generate a large slip during an earthquake.
IODP Exp. 343 (JFAST), which conducted drilling in the shallow part of the plate boundary at the Japan Trench, found that the plate boundary fault had been developed in low-friction pelagic claystone and that strain had been accumulated in the frontal prism of the hanging wall and stress was released during the earthquake. On the other hand, because of limited sample recovery from the upper prism during the JFAST, structural development processes and material characteristics of the upper prism have not been clarified.
The objectives of this project are (1) to elucidate the formation processes of the hanging wall where strain accumulates, and (2) to clarify the temporal and spatial physical and structural characteristics of the sediments in the hanging wall. These objectives will contribute to the understanding of the pre-, co-, and post-seismic processes of a mega-earthquake. To achieve this goal, we plan to construct a gamma- ray stratigraphy, measure the anisotropy of various physical properties, and perform microstructural analysis. The structural and physical characteristics obtained in this project are comparable with these not only from JFAST but also from JTRACK.
Proposed target coresLeg 56 Site 434-Hole B 1-4, 7-11, 14-20, 24-28, 30, 32-37
Leg 57 Site 440-Hole B 1, 3-43, 45-71
Leg 56 Site 436 1-42
Leg 57 Site 439 14-15, 36, 38
Exp. 343 C0019 1-10, 12-16, 19-21 (Only observation and sampling)
Sample request periodClosed (until 28, January 2024)
Click here to see how to submit a sample request.
Sampling party implementation periodMarch 3-14, 2024
Link to the proposalReC-003 Proposal

Implementation Number:ReC23-03

Proposal numberReC-002
Proposal titleThe Japan Sea paleoceanography and paleoclimatology during the Miocene
Lead ProponentArisa Seki, Shinshu University
Scientific ObjectivesTo understand the oceanic environment changes in the warmer-than-today world are important for addressing future global warming. In this project, we reconstruct short time scale oceanographic changes of the Japan Sea during the warm Miocene period. To understand oceanographic condition properly, comparison of sediments deposited at different water depth at the same time is necessary. Since sediments taken by IODP Exp. 346 provide many scientific results, the Miocene oceanographic reconstruction is limited because comparison of different water depth is available only during sort period. During ODP Leg 127, many Miocene sediments were drilled from the deeper part of the Japan Sea. However, high-resolution (less than orbital scale) oceanographic reconstruction has not been conducted enough.
Therefore, in this project, our objective is to reconstruct millennial-scale, three dimensional oceanographic changes during the Miocene. We will especially focus on;
a) centennial to millennial scale oceanographic changes recorded in laminated sediments.
b) rapid warming event and subsequent oceanographic condition. The detailed objective is;
1) Revise age models of Leg 127 cores by tephra dating, revising biostratigraphy, and correlation of cores to Exp. 346 cores utilizing chemical composition (XRF core scanner), CT, and logging data.
2) Reconstruct the high-resolution oceanographic condition changes for each Site utilizing XRF core scanner result and core observation, and compare the reconstructed conditions with other Sites deposited in different water depth at the same time, including on-land sections.
3) Sampling of the sediments for further analysis to more precisely understand oceanographic changes and background climate changes.
Proposed target coresLeg 127 Site 794 Hole B 1R-27R
Leg 127 Site 795 Hole B 1R-33R
Leg 127 Site 797 Hole B 24X-53X
Leg 127 Site 797 Hole C 1R-8R
Exp. 346 Site U1425 Hole B 23H-54H
Exp. 346 Site U1425 Hole D 20H-67H
Exp. 346 Site U1430 Hole A 9H-29H
Exp. 346 Site U1430 Hole B 9H-27H
Sample request periodNow accepting (until 29, April 2024)
Click here to see how to submit a sample request.
Sampling party implementation periodPlanned Scheduled on 3 - 12 July 2024
Link to the proposalReC-002 Proposal

Implementation Number: ReC23-01

Proposal numberReC-001
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 periodAugust 27 - September 05, 2023
Link to the proposalReC-001 Proposal
Implementation ReportRec23-01_Report