Narrow shelf canyons vs. wide shelf canyons: Two distinct types of Black Sea submarine canyons

摘要

The purpose of this study was to characterize the Black Sea canyons associated with contrasting natural environmental conditions from two Black Sea basin regions: the northwesternorthern and the northeastern/eastern zones. The canyon-associated relief, the morphology of the continental shelf and the location of the canyon heads in the two Black Sea areas were analysed and compared. The canyon network reconstruction led to the conclusion that the canyon system pattern is different in the northwestern and northern Black Sea zones compared to the canyon system in the eastern Black Sea zone. Sediments in the deep sea fan areas were supplied in different manners by the canyon systems from the two marine study areas. According to the important different characteristics revealed by this study, the submarine canyons located in the northwesternorthern vs. the northeastern/eastern Black Sea zones appear as two distinct types, namely wide-shelf canyons and narrow-shelf canyons, with specific genetic and morphologic characteristics. The response to sea-level variation reveals an important distinction between the wide-shelf canyons and the narrow-shelf canyons. In high-stand conditions, when the shelf is immersed, the wide-shelf canyons become inactive, whereas the narrow-shelf canyons are active in both low-stand and high-stand conditions.