Age and Thickness of the Lithosphere within the Western and Eastern Basins of the Black Sea according to Geophysical Data

[摘要] The ages of the western and eastern basins of the Black Sea have been estimated on the basis of heat-flow data. The obtained ages (70-60 Ma) are in good accord with the time of basins' origin as determined from seismic and magnetic data. During this time, the Black Sea opened as a back-arc basin to the north of the Pontide magmatic arc. The arc prehistory of the Pontides is confirmed by the existence of relict mantle seismicity, which is most active in the eastern Pontides. Nearly synchronous times of origin for the western and eastern basins supports the concept of their simultaneous genesis as a result of clockwise rotation of the Andrusov Rise. The lithosphere thickness of both basins (60-65 km) was also determined using geothermal data. The calculated thickness of the lithosphere corresponds to this one for oceanic lithosphere of Early Cenozoic age; this is confirmed by study of velocity dispersion for surface waves which propagate from Mediterranean earthquakes to seismic stations of the Crimea and western Caucasus. Analysis of heat-flow data strongly suggests that the sea floor of the western basin is underlain by oceanic crust, while the sea floor of the eastern basin is characterized by a thinned continental crust. According to geothermal modelling, the thickness of the granite layer in the eastern basin is about 4 km and that of the basaltic layer is approximately 6 km. The estimated thickness of crustal layers within this basin is confirmed by seismic data.

[学科分类] 地球科学(综合)

[关键词] Black Sea;heat flow;sea floor age;surface waves;lithosphere thickness