Conical faults apparent in a 3D seismic image

AbstractMap-scale geologic faults with a conical shape are apparent in a public-domain 3D seismic image of block F3 in the Dutch sector of the North Sea. These cone-shaped normal faults exist among many polygonal normal faults in fine-grained clay sediments. The conical faults were discovered using new algorithms for seismic image processing, but they are apparent without that processing. They appear circular in horizontal image slices and have an inverted-V shape in vertical sections for any azimuth through their vertical axes of symmetry. They form horsts bounded by planar strata above and below, with maximum throws of about 35 m roughly halfway between their bases and tops. The bases are up to 1 km wide, and dips of the conical faults are in the range 35o–38o. Because polygonal faults exist elsewhere at or near the seafloor with dips of about 60o, most such faults likely formed close to the depositional interface; the much lower dips of deeply buried faults, such as the faults observed here, are likely...

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