Strasser Michael

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Strasser
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Michael
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  • Article
    Event-dominated transport, provenance, and burial of organic carbon in the Japan Trench
    (Elsevier, 2021-03-24) Schwestermann, Tobias ; Eglinton, Timothy I. ; Haghipour, Negar ; McNichol, Ann P. ; Ikehara, Ken ; Strasser, Michael
    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.
  • Article
    Tectonically-triggered sediment and carbon export to the Hadal zone
    (Nature Publishing Group, 2018-01-09) Bao, Rui ; Strasser, Michael ; McNichol, Ann P. ; Haghipour, Negar ; McIntyre, Cameron P. ; Wefer, Gerold ; Eglinton, Timothy I.
    Sediments in deep ocean trenches may contain crucial information on past earthquake history and constitute important sites of carbon burial. Here we present 14C data on bulk organic carbon (OC) and its thermal decomposition fractions produced by ramped pyrolysis/oxidation for a core retrieved from the >7.5 km-deep Japan Trench. High-resolution 14C measurements, coupled with distinctive thermogram characteristics of OC, reveal hemipelagic sedimentation interrupted by episodic deposition of pre-aged OC in the trench. Low δ13C values and diverse 14C ages of thermal fractions imply that the latter material originates from the adjacent margin, and the co-occurrence of pre-aged OC with intervals corresponding to known earthquake events implies tectonically triggered, gravity-flow-driven supply. We show that 14C ages of thermal fractions can yield valuable chronological constraints on sedimentary sequences. Our findings shed new light on links between tectonically driven sedimentological processes and marine carbon cycling, with implications for carbon dynamics in hadal environments.
  • Article
    Earthquake-enhanced dissolved carbon cycles in ultra-deep ocean sediments
    (Nature Research, 2023-09-11) Chu, Mengfan ; Bao, Rui ; Strasser, Michael ; Ikehara, Ken ; Everest, Jez ; Maeda, Lena ; Hochmuth, Katharina ; Xu, Li ; McNichol, Ann P. ; Bellanova, Piero ; Rasbury, E. Troy ; Kolling, Martin ; Riedinger, Natascha ; Johnson, Joel E. ; Luo, Min ; Marz, Christian ; Straub, Susanne ; Jitsuno, Kana ; Brunet, Morgane ; Cai, Zhirong ; Cattaneo, Antonio ; Hsiung, Kanhsi ; Ishizawa, Takashi ; Itaki, Takuya ; Kanamatsu, Toshiya ; Keep, Myra ; Kioka, Arata ; McHugh, Cecilia M. G. ; Micallef, Aaron ; Pandey, Dhananjai ; Proust, Jean Noel ; Satoguchi, Yasufumi ; Sawyer, Derek ; Seibert, Chloe ; Silver, Maxwell ; Virtasalo, Joonas ; Wang, Yonghong ; Wu, Ting-Wei ; Zellers, Sarah
    Hadal trenches are unique geological and ecological systems located along subduction zones. Earthquake-triggered turbidites act as efficient transport pathways of organic carbon (OC), yet remineralization and transformation of OC in these systems are not comprehensively understood. Here we measure concentrations and stable- and radiocarbon isotope signatures of dissolved organic and inorganic carbon (DOC, DIC) in the subsurface sediment interstitial water along the Japan Trench axis collected during the IODP Expedition 386. We find accumulation and aging of DOC and DIC in the subsurface sediments, which we interpret as enhanced production of labile dissolved carbon owing to earthquake-triggered turbidites, which supports intensive microbial methanogenesis in the trench sediments. The residual dissolved carbon accumulates in deep subsurface sediments and may continue to fuel the deep biosphere. Tectonic events can therefore enhance carbon accumulation and stimulate carbon transformation in plate convergent trench systems, which may accelerate carbon export into the subduction zones.