The palaeogeographic outlines of the Caucasus in the Jurassic: The Caucasian Sea and the Neotethys Ocean

Abstract

The Caucasian Sea, fringing the northern margin of the Jurassic Neotethys Ocean, largely covered the Caucasus. Continental, shallow-marine and deep-marine palaeoenvironments delineate palaeogeographic outlines for three significant time slices: the Late Toarcian, the Early Bajocian and the Middle Oxfordian. These new palaeogeographic outlines of the Caucasus and adjacent territories match the Neotethys Ocean reconstructions. In the Late Toarcian the Caucasian Sea embraced the Greater Caucasus Basin and the Black Sea Caspian Sea Basin, which were divided by the Northern Transcaucasian Arc; it opened to the Neotethys Ocean which covered the Exterior Caucasian Basin. In the Early Bajocian, the Caucasian Sea only embraced the Greater Caucasus Basin; it opened the epicontinental seas of the Russian Platform, connecting them with the Neotethys Ocean by straits between islands of the Transcaucasian Arc. In the Middle Oxfordian, the Caucasian Sea which further embraced the Greater Caucasus Basin had its outer shelf fringed by carbonate build-ups. The connection between the Russian Platform shallow sea and the Neotethys Ocean was maintained. In the course of the Jurassic, a seaway developed along the northern margin of the Neotethys, of which the Caucasian Sea became a significant part.Kavkasko more zahvatalo je severni obod jurskog Neotetiskog okeana i velikim delom je prekrivalo Kavkaz. Kontinentalne, plitkovodne i dubokovodne paleosredine ocrtavaju paleogeografske okvire tri znacajna vremenska razdoblja: gornji toar, donji bajes i srednji oksford. Ove nove paleogeografske granice Kavkaza i susednih oblasti uklapaju se u rekonstrukciju Neotetiskog okeana. U gornjem toaru Kavkasko more je obuhvatalo Veliki Kavkaski basen i Crno more - Kaspijski morski basen, koji su bili razdvojeni Severnim transkavkaskim lukom koji se otvarao prema Neotetiskom okeanu koji je prekrivao spoljasnji Kavkaski basen. Za vreme donjeg bajesa, Kavkasko more je zahvatalo samo Veliki Kavkaski basen; ono je bilo otvoreno prema epikontinentalnom moru Ruske platforme povezujuci ga sa Neotetiskim okeanom zemljouzima izmedju ostrva Transkavkaskog luka. Tokom srednjeg oksforda stvarale su se karbonatne naslage po obodu spoljasnjeg selfa Kavkaskog mora, koje je i dalje zahvatalo Veliki Kavkaski basen. Odrzavala se veza izmedju plitkovodne Ruske platforme i Neotetiskog okeana. U toku jure postojao je morski prolaz duz severnog oboda Neotetisa, gde je Kavkasko more zauzimalo njegov znacajni deo.