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Biogeochemistry of New Zealand Cretaceous-Cenozoic hydrocarbon-seeps (NZGeobiology)
Date du début: 1 août 2008, Date de fin: 31 juil. 2010 PROJET  TERMINÉ 

Hydrocarbons accumulate in the Earth’s geosphere and can be released into the oceans and atmosphere, driven by geologic and tectonic events. On marine continental margins, faulting and over-pressured sedimentary pore-fluids can initiate fluid movement from depth, to manifest as subsurface fluid migration (plumbing) and seafloor hydrocarbon seepages or gas hydrates. Seeps and gas hydrates serve as markers for petroleum exploration, shape the biogeographic distribution and evolution of chemosynthetic ecosystems, and may trigger slope instability or climate change. In New Zealand’s North Island, these short-timed fluid-flow features leave behind robust signatures in authigenic seep-carbonates. These carbonates were precipitated due to anaerobic oxidation of methane (AOM) and will be investigated by detailed molecular-isotopic biomarker analyses in order to deliver their key messages. This pioneering study on lipid biomarkers in ancient NZ-seeps will provide important information on 1) scavenging former activity at methane-seeps performed by a microbial community inhabiting ancient methane-seeps, 2) impact of abrupt changes in extreme environments on methane-seeps communities 3) the composition of the microbial community at methane-seeps, 4) ecological functions of certain microbial groups. Results obtained on lipid biomarkers of ancient methane-seeps will be a major part of an international collaborative research programme which aims are to elucidate how-fluid flow manifestations, namely hydrocarbon seeps and gas hydrates, interact with biosphere-hydrosphere-geosphere interfaces over geologic time. It will also assist in linking New Zealand’s past and present chemosynthetic communities to those which occur around the Pacific Rim in the extreme environments of hydrothermal vents and hydrocarbon seeps.

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