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Reverse Magnetized Lava Dome Interpreted from 3-D Seismic, Gravity and Previous HitMagneticNext Hit Data in the Turkish Black Sea


Introduction The Black Sea is an underexplored deep water basin with significant hydrocarbon potential. It evolved as a rift basin in a back-arc setting with subsequent compression events that added complexity to the structural setting. Shell acquired a recent 3D seismic survey along with gravity and Previous HitmagneticNext Hit data to pursue its exploration efforts in the region. The newly acquired data showed a basin centre dome like structure. Seismic and potential data were integrated to resolve its nature and origin. Method Different geological scenarios were investigated for this dome feature; like mud volcano/salt dome/”real” volcano. The Previous HitmagneticNext Hit data were analysed to estimate the depth to Previous HitmagneticNext Hit sources and 2D gravity/Previous HitmagneticNext Hit models were generated with various parameters; structural architecture, densities and susceptibilities to validate one geological scenario over the others. Results The Bouguer gravity data shows a moderate (2mGal) positive anomaly whereas the reduced to pole total Previous HitmagneticNext Hit intensity data indicates a large (-150nT) negative anomaly. The model suggests that the feature possesses slightly high density and very high Previous HitmagneticNext Hit susceptibility relative to the surrounding rocks. The negative Previous HitmagneticNext Hit anomaly can be modelled by a high Koenigsberger ratio with a large amount of remanent magnetized material which cooled down below Curie temperature at a time when the Previous HitmagneticNext Hit polarity was reversed. The gravity and Previous HitmagneticTop models, integrated with the seismic interpretation, rule out mud volcanoes, salt and metamorphic rocks; and point to an igneous lava dome. Based upon geological knowledge of the area, the formation and cooling of the body below Curie temperature is estimated between late Cretaceous (Santonian) and Eocene. Paleomagnetic study shows a number of polar reversals during this period.