Do major neogene hiatuses in the Ciscaucasian semi-enclosed basin (Eastern Paratethys, southwestern Russia) record eustatic falls?

Abstract

Hiatuses in semi-enclosed basins can be caused by either eustatic falls or local tectonic uplifts. The Ciscaucasian basin is located in the south of European Russia. In the Neogene, it belonged to the Eastern Paratethys domain. On the basis of available stratigraphic data, four major hiatuses are traced in this basin as erosional surfaces or lengthy sedimentation breaks, namely the Tarkhanian, Middle/Upper Sarmatian, Sarmatian/Maeotian, and Kimmerian hiatuses. They are documented in most of the areas of the study basin. The three earlier hiatuses mark short-term and nearly isochronous, basinwide sedimentation breaks, whereas the latter hiatus is diachronous, embracing more than 2 myr. All reported hiatuses record the eustatic falls. Consequently, we argue that eustatic processes controlled sedimentation in the Ciscaucasian basin throughout the entire Neogene. This means the basin was connected to the open ocean throughout this period, with important consequences for our understanding of watermass history in the Mediterranean and Paratethyan basins further west and south.Hijatusi kod poluzatvorenih bazena mogu nastati eustatitickim padovima ili tektonskim izdizanjem. Predkavkaski bazen se nalazi na jugu evropskog dela Rusije. U neogenu bazen je pripadao Istocnom Tetisu. Na osnovu raspolozivih stratigrafskih podataka cetiri glavna hijatusa su uocena u ovom bazenu, bilo kao erozione povrsine ili duzi sedimentacioni prekidi: tarkhanski, srednje/gornje sarmatski, sarmatski/meotski i kimerijski. Oni su dokazani na vise mesta proucavanog bazena. Prva tri hijatusa su oznaceni kratkim, priblizno izohronim i sirokim sedimentacionim prekidima, dok je zadnji hijatus dijahron, trajao je vise od 2 miliona godina. Svi pomenuti hijatusi ukazuju na eustaticke padove. To je bio razlog da dokazemo da u Predkavkaskom bazenu eustaticki procesi kontrolisu sedimentaciju kroz ceo neogen i da je bazen bio u vezi sa otvorenim okeanom za vreme tog perioda. Ovi podaci objasnjavaju rasprostranjenje vodenih povrsina u zapadnim i juznim delovima mediteranskih i paratetiskih bazena za vreme neogena.