A pockmark field in the central Barents Sea; gas from a petrogenic source?

Abstract

A pockmark field has been encountered in the northwestern Barents Sea, 50 km southeast of Hopen island. High resolution seismic records and side scan sonographs show that the features are small (10-20m diameter), shallow (< 1 m deep) structures that may cover up to 25% of the sea floor in local areas. Pockmark existence seem to be dependent on the presence of soft, Holocene mud. In more firm sea-floor they seem to concentrate in the partly infilled troughs of iceberg plough marks. The pockmark distribution, characteristics of the underlying sedimentary bedrock and thin cover of glacigenic sediments in the area, indicate they are formed by ascending gas from a deeper, probably petrogenic source. It is inferred that pockmarks may be found in larger parts of the Barents Sea.