Publication Date:
2022-10-26
Description:
© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Schwestermann, T., Eglinton, T., I., Haghipour, N., McNichol, A. P., Ikehara, K., & Strasser, M. Event-dominated transport, provenance, and burial of organic carbon in the Japan Trench. Earth and Planetary Science Letters, 563, (2021): 116870, https://doi.org/10.1016/j.epsl.2021.116870.
Description:
The delivery of organic carbon (OC) to the ocean's deepest trenches in the hadal zone is poorly understood, but may be important for the carbon cycle, contain crucial information on sediment provenance and event-related transport processes, and provide age constraints on stratigraphic sequences in this terminal sink. In this study, we systematically characterize bulk organic matter (OM) and OC signatures (TOC/TN, C, 14C), as well as those from application of serial thermal oxidation (ramped pyrolysis/oxidation) of sediment cores recovered along an entire hadal trench encompassing high stratigraphic resolution records spanning nearly 2000 years of deposition. We analyze two cores from the southern and northern Japan Trench, where submarine canyon systems link shelf with trench. We compare results with previously published data from the central Japan Trench, where canyon systems are absent. Our analyses enable refined dating of the stratigraphic record and indicate that event deposits arise from remobilization of relatively surficial sediment coupled with deeper erosion along turbidity current pathways in the southern and central study site and from canyon flushing events in the northern study site. Furthermore, our findings indicate deposition of predominantly marine OC within hemipelagic background sediment as well as associated with event deposits along the entire trench axis. This implies that canyon systems flanking the Japan Trench do not serve as a short-circuit for injection of terrestrial OC to the hadal zone, and that tropical cyclones are not major agents for sediment and carbon transfer into this trench system. These findings further support previous Japan Trench studies interpreting that event deposits originate from the landward trench slope and are earthquake-triggered. The very low terrestrial OC input into the Japan Trench can be explained by the significant distance between trench and hinterland (〉180 km), and the physiography of the canyons that do not connect to coast and river systems. We suggest that detailed analyzes of long sedimentary records are essential to understand OC transfer, deposition and burial in hadal trenches.
Description:
The cruise was supported by the German Bundesministerium für Bildung und Forschung (BMBF 03G0251A) and the Deutsche Forschungsgemeinschaft. We acknowledge the Kochi core repository for additional surface samples of Japanese Cruises. Al Gagnon and Mary Lardie are thanked for their great help and technical assistance with the RPO instrument at NOSAMS. APM and the NOSAMS work were supported by the National Science Foundation Cooperative Agreement OCE-1239667. We appreciate the assistance from members of the Laboratory of Ion Beam Physics for the AMS measurements. Rui Bao is acknowledged for helpful discussions. A special thank you goes to Madalina Jaggi for her technical assistance for the C analysis of rinsed samples. This study was supported by the Austrian Science Fund (FWF P29678-N28) and a postgraduate grant by the International Association of Sedimentologists (IAS). We also acknowledge constructive support by the two reviewers (Jordon Hemingway and an anonymous). The authors declare no conflict of interests. The bathymetric data used in figure 1 is available at JAMSTEC-DARWIN database (http://www.godac.jamstec.go.jp/darwin/e) and Bundesamt für Seeschifffahrt und Hydrographie (https://www.bsh.de/DE/DATEN/Ozeanographisches_Datenzentrum/Vermessungsdaten/Nordpazifischer_Ozean/nordpazifik_node.html). Data of carbon analyses are displayed in the supporting information and also available from the corresponding author on reasonable request.
Keywords:
Carbon isotopes
;
Carbon provenance
;
Hadal zone event-stratigraphy
;
Carbon transfer
;
Japan Trench
;
Ramped Pyr/Ox
Repository Name:
Woods Hole Open Access Server
Type:
Article
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