Abstract
An anomalous strong, shallow reflector has been observed in several deep-tow subbottom profiler records in a region of the northern Black Sea characterised by seafloor fluid seeps, mud volcanoes, and the occurrence of gas hydrates. The digital data were processed using adapted seismic processing methods. Synthetic seismograms created to model representative traces from the observed profiles require anomalous alternations of acoustic properties in the upper sediments which can best be explained by interbedded layers of normal sediments and sediments with gas hydrates. The enigmatic strong reflector can be explained by constructive interference of reflections from five of these thin layers. It is proposed that the uppermost region of the gas hydrate stability zone here is represented by thinning layers of interbedded gas hydrates or layers with lower concentrations of gas hydrates.
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Acknowledgements
We acknowledge the officers and crew of both the R/V Professor Logachev and the R/V Gelendzhik, and the technical experts on both those ships who were responsible for the excellent data with which we have worked, from Yuzhmorgeologiya. The final version of the manuscript was improved thanks to comments and suggestions from Herve Nouze and Pieter van Rensbergen whom we thank for their thoughtful reviews of the submitted version. Funding of the research was gratefully received from UNESCO-IOC, Russian Ministry of Science and Education, and the Netherlands Organisation for Scientific Research NWO (through project number 750.195.02). This is contribution no. 2003-10-02 of the Netherlands Research School of Sedimentary Geology (NSG).
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Woodside, J.M., Modin, D.I. & Ivanov, M.K. An enigmatic strong reflector on subbottom profiler records from the Black Sea—the top of shallow gas hydrate deposits. Geo-Mar Lett 23, 269–277 (2003). https://doi.org/10.1007/s00367-003-0149-7
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DOI: https://doi.org/10.1007/s00367-003-0149-7