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Response of gas hydrate systems to subduction-zone processes on the Nothern Hikurangi Margin, New Zealand

Urheber*innen

Pecher,  Ingo Andreas
External Organizations;

Oluwunmi,  Paul
External Organizations;

Djeffal,  Adnan
External Organizations;

Bangs,  Nathan L.
External Organizations;

Crutchley,  Gareth James
External Organizations;

Mountjoy,  Joshu J.
External Organizations;

Villinger,  Heinrich W.
External Organizations;

Barnes,  Philip
External Organizations;

/persons/resource/katjah

Heeschen,  Katja
3.1 Inorganic and Isotope Geochemistry, 3.0 Geochemistry, Departments, GFZ Publication Database, Deutsches GeoForschungsZentrum;

Dugan,  Brandon
External Organizations;

Reagan,  Matthew T.
External Organizations;

Moridis,  George J.
External Organizations;

Archer,  Rosalind
External Organizations;

Saffer,  Demian M.
External Organizations;

Wallace,  Laura M.
External Organizations;

LeVay,  Leah
External Organizations;

Petronotis,  Katerina E.
External Organizations;

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Zitation

Pecher, I. A., Oluwunmi, P., Djeffal, A., Bangs, N. L., Crutchley, G. J., Mountjoy, J. J., Villinger, H. W., Barnes, P., Heeschen, K., Dugan, B., Reagan, M. T., Moridis, G. J., Archer, R., Saffer, D. M., Wallace, L. M., LeVay, L., Petronotis, K. E. (2018): Response of gas hydrate systems to subduction-zone processes on the Nothern Hikurangi Margin, New Zealand, (AGU Abstracts), AGU Fall Meeting 2018 (Washington D. C. 2018), T54C-08.


Zitierlink: https://gfzpublic.gfz-potsdam.de/pubman/item/item_3946927
Zusammenfassung
International Ocean Discovery Program (IODP) Expeditions 372 and 375 targeted the Northern Hikurangi subduction margin east of New Zealand. These expeditions, combined with a number of site surveys, provided us with a vast dataset that sheds new light on the evolution of gas hydrate systems in subduction-zone settings. Our studies focus on the region near the up-dip limit of the gas hydrate stability field where hydrates are particularly susceptible to changes in pressure or temperature. Double-BSRs are encountered at several locations in the study area. From pore water chemistry and head space-gas analysis, there are no indications for any thermogenic gases, making it unlikely that double-BSRs form from fractionation of a thermogenic gas mix. Beneath a ridge in the northern part of our study area, double-BSRs are thought to be linked to depressurization from tectonic uplift. Further south near the IODP drilling transect, double-BSRs may be the response to the thermal signal from a sedimentation pulse. Modelling suggests gas hydrate dissociation in conjunction with these double-BSRs to take place over thousands of years. Actively dissociating gas hydrates may therefore be present between the double-BSRs. Furthermore, results from a heat flow transect near the up-dip limit of the hydrate stability field indicate that gas hydrates are actively dissociating. Anomalies in thermal gradients suggest that latent heat from ongoing gas hydrate dissociation may act as a buffer to transient advective heat flux. Our findings suggest that gas hydrate systems that respond to subduction-related processes such as uplift or fluid pulses may often be in a transient state leading to on-going hydrate dissociation over thousands of years. Such ongoing gas hydrate dissociation could affect a number of seafloor processes, e.g., causing overpressure, affecting pore water chemistry, and distorting thermal and hydraulic regimes.