Pressure coring, logging and subsampling with the HYACINTH system
P. J. Schultheiss, T. J. G. Francis, M. Holland, J. A. Roberts, H. Amann, Thjunjoto, R. J. Parkes, D. Martin, M. Rothfuss, F. Tyunder, P. D. Jackson, 2006. "Pressure coring, logging and subsampling with the HYACINTH system", New Techniques in Sediment Core Analysis, R. G. Rothwell
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The HYACINTH suite of equipment has been developed to investigate the pressure sensitive behaviour of sedimentary formations up to 250 bar (25 MPa). It does this by collecting pressure-preserved samples from boreholes that can be retrieved, subsampled and analysed in controlled conditions in the laboratory. This paper reviews the development of the system, how it originated from the need to better understand the nature and distribution of gas hydrates beneath the sea bed, and its achievements to date. While gas hydrates continue to be the major scientific and commercial impetus for using, and further developing, this pressure-sampling technology, other important scientific driving forces, including the growing interest in the deep biosphere beneath the sea floor, are playing an important role. We review the downhole tools, the transfer system and the suite of different pressure chambers that are required to make a complete working system. Non-destructive logging of cores contained in pressure chambers, using existing gammaand X-ray techniques, is discussed, as are future logging techniques that will have sensors embedded within the pressure chambers. Subsamples can now be taken at full pressure and transferred into specialized chambers where intrusive measurements and experiments can be performed (e.g. inoculation chambers for microbiology). The versatile philosophy behind the integrated systems will enable future developments to be made by third parties who want to obtain subsamples at in situ pressure from the HYACINTH system. We conclude by reviewing some of the highlights of the HYACINTH operations on ODP Leg 204 where the downhole tools retrieved cores containing gas hydrates (up to 40% by volume) that were subsequently logged on board in the laboratory. These data have already contributed to the scientific understanding of the nature and distribution of gas hydrates beneath the seabed in one area on the Oregon Margin off the USA.
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Marine sediment cores are the fundamental data source for information on seabed character, depositional history and environmental change. They provide raw data for a wide range of research including studies of climate change, palaeoceanography, slope stability, oil exploration, pollution assessment and control, seafloor survey for laying cables, pipelines and construction of seafloor structures. During the last three decades, a varied suite of new technologies have been developed to analyse cores, often non-destructively, to produce high-quality, closely spaced, co-located downcore measurements. These techniques can characterize sediment physical properties, geochemistry and composition in unprecedented detail. Palaeoenvironmentally significant proxies can now be logged at decadal, and in some cases, annual or sub-annual scales, allowing highly detailed insights into climatic history and associated environmental change. These advances have had a profound effect on many aspects of the Earth Sciences and our understanding of the Earth's history.
In this volume, recent advances in analytical and logging technology and their application to the analysis of sediment cores are presented. Developments in providing access to core data and associated datasets, and advances in data mining technology in order to integrate and interpret new and legacy datasets within the wider context of seafloor studies are also discussed.