A promising methodology for the detection of pockmarks activation in nearshore sediments

摘要

A promising methodology for the detection of pockmarks activation is suggested in the present work. Thirteen sediment cores were collected from the eastern part of the Gulf of Patras in an active pockmark field area. Cores were collected both inside and outside pockmarks. The upper 2 cm (surficial sample) from each core was analysed for grain size, organic carbon (C{sub}(org)), Ca, Fe, Co, Cu, Mn, Pb, and Zn concentrations. In order to investigate any potential effect of the pockmark field activity on the distribution of heavy metals in the surficial sediments, an R-mode factor analysis was applied onto the grain size classes, C org and metals concentrations. Factor analysis shows three main factors: a domestic sewage pollution factor, the Mn/Fe oxides, and the carbonate sedimentation. The increased sandy material, the low C{sub}(org) content, as well as the lack of C{sub}(org)/heavy metals association follows a specific NW-SE transect in the centre of the surveyed pockmark field, suggesting pockmarks activity. Based on the remarkable results of this study, the statistical treatment of granulometric and inorganic geochemical data selected from inner and outer sites of pockmarks, can constitute a unique means to the detection of the individual active pockmarks located in a wide pockmark field. In addition, we believe that the proposed methodology is not restricted to the Gulf of Patras, but can be applied in pockmark fields all over the world.