GAS CHIMNEYS IN THE NW BLACK SEA NEAR THE KALANCHAK PALEOBRIVER

Abstract

The publication is based on a large body of data on gas outcrops in the northwest of the Black Sea, and in particular, the paleo-Kalanchak area. The material was obtained during the voyages carried out on the R/V of the Department of Marine Geology and Sedimentary Ore Formation of the National Academy of Sciences of Ukraine, as well as data from literary sources. More than 3000 methane sips were identified in the study area. The vast majority of gas emissions in the area of paleo-river Kalanchak, as well as in other areas of the northwestern sector of the Black Sea, is confined to the upper part of the continental slope and the adjacent area of the shelf. Practically it is a band 45 km wide on both sides of the shelf edge. Seismic and acoustic profiles were studied in this article. Their analysis indicates that gas chimneys are not distributed randomly but concentrated in specific locations. A certain relationship between the spatial distribution of methane outcrops on the seafloor and geomorphological structures, as well as tectonic structure, primarily faults is traced. Gas chimneys are associated with various forms of seafloor topography, but their greatest number is located at the mouths of paleo-river canyons. The article provides more detailed geomorphological information of the paleo-river network of the NW Black Sea. In the estuarine canyon, gas emissions form along the sedimentary ridges, gas chimneys appear at the bottoms of canyons, their peripheries, or near the dumps of submarine landslides, where the sedimentary cover is disturbed by mass transport. On the shelf, the greatest concentration of gas chimneys is found in circular and elongated depressions (pockmarks). Based on the study of acoustic profiles, gas chimneys of the Paleo-Kalanchak part of the Black Sea were classified according to a few features: the depth of location, height of gas release, gas flow capacity, form of gas release, mode of operation. The results of the research are also presented in graphical materials (histograms of gas chimneys distribution by depth and height of gas discharge, map of sip location by the Paleo-Kalanchak River area).