Palaeoecological importance of trace fossils from the Permian, Jurassic and Cretaceous deposits of Mountainous Adygeya

Abstract

Trace fossils may be of crucial importance for palaeoenvironmental reconstructions, which is demonstrated by example of new ichnological finds in Mountainous Adygeya. Two horizons with trace fossils from the Lower-Middle Permian molasse indicate continental and marine depositional environments and their rapid change. Bioturbation in shales of the Lower-Middle Jurassic permits to establish punctuated or low-intensity dysoxic conditions that explain continuous development of biota in unfavorable environments. The presence cf. Thalassinoides isp. with untypical bifurcation in the Aptian (Lower Cretaceous) glauconite-bearing sandstones questions the local depositional setting and allows to suppose that the oxygen concentration in sea water was characteristic for formation of neither glauconite, nor typical representatives of the noted ichnogenus.

Keywords

• следы жизнедеятельности
• ихнология
• палеосреда
• горная адыгея
• пермский период
• юрский период
• меловой период