DISCOVERY OF SOLID GAS HYDRATE IN THE ROCK AT THE FOOT OF THE CONTINENTAL SLOPE OF THE CRIMEA

Abstract

One of the tasks of the 21st cruise of the RV Yevpatoriya in the Black Sea in 1988 was to search for accumulations of gas hydrates supplied by an underwater mud volcano, and inferred to exist there by analogy with those found earlier in the southern part of the Caspian Sea. The search was made off the southest coast of the Crimea, in the Oligocene-Miocene (Maykopian) Sorokin basin, which is known to contain diapir structures and can be considered to be an extension of the Kerch-Taman basin. The exploratory techniques used were continuous echo-sounding, and continuous seismic profiling (CSP). The seismoacoustic operations resulted in the discovery of seven diapirs, which appear on the CSP traces as unstratified bodies that penetrate the layered rock. The gas hydrates were found in four cores taken on a circle about 100 m radius and centered at 44° 17′ 4 N, and 34° 58′ 4 E. The most striking find was recorded in a clay breccia. In the other three sediment cores, the gas hydrate was confined to the bedded silty polite (turbidite) surrounding the diapir and showing obvious signs of deformation also obviously produced by the growth of the diapir. The success of this search means that the Black Sea, like the southern area of the Caspian Sea, is a submarine mud-volcano gas-hydrate region.