|mhorn||Дата: Tuesday, 27.10.2009, 00:01 | Сообщение # 1|
|Shchepetova E. V. (2009) Sedimentology of Volgian oil shale formation (Upper Jurassic, Panderi Zone) in North Russian Plate // Bull. Soc. Natur. Moscow. V.84. no.4. P.74-89. [in Russian] |
Several lithostratigraphic units of the Middle Volgian oil shale formation (panderi ammonite Zone) outcropped along Syssola River (Vadyu and Koygorodok sections) and Kobra River (Sinegorie section) were studied to reveal main features of sedimentary dynamics in the northern part of the Volgian epicontinental sea of the Russian Plate. It is suggested that clear influence of cool waters of the close Arctic basin recognized in studied sections. Cooling and humidization resulted in more intensive terrigenous and nutrient input to this part of the basin and decrease of sea water temperature with arctic-boreal fauna migration. From the other hand, this conclusion contradicts with data on ammonite occurrence in the Middle Volga and Orenburg areas, where Boreal Pavloviids predominates in the lowermost part of the Panderi Zone. Moreover, Zarajskensis Subzone characterized by pronounced northwards immigration of virgatitids (Zaraiskites regularis).
Middle Jurassic - Lower Cretaceous ammonites & aptychi