--> ABSTRACT: Appearence and Dissapearence of Cyclicity in the Cenomanian of the SW Crimea (Ukraine): Global Climatic Orbital Forcing versus Local Tectonic Factor, by Ruslan Rustemovich Gabdullin; #90906(2001)

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Ruslan Rustemovich Gabdullin1

(1) Moscow State University, Moscow, Russia

ABSTRACT: Appearence and Dissapearence of Cyclicity in the Cenomanian of the SW Crimea (Ukraine): Global Climatic Orbital Forcing versus Local Tectonic Factor

Rhythmically bedded marls and limestones were studied in the Cenomanian deposits of SW part of Mountain Crimea in Ukraine. Types of rhythms can be classified due to lithology and their paleogeographic position. Shallow marine types: 1- marl-sandy marl (Early Cenomanian, Selbuhra section); 2 - marl-limestone (Late Cenomanian, Mender section). Deep marine types: 3 - marl, marly limestone - limestone (Middle Cenomanian, Selbuhra section); 4 - limestone-limestone (Late Cenomanian); 5 - marl-marly clay rhythms in black shales (Late Cenomanian). Diversity of rhythm`s types in the Late Cenomanian (Mender, Selbuhra, Aksu-Dere sections) is connected with sedimentation of carbonates in different parts of the basin. Dilution cycles and possible diagenetic overprint are responsible for occurrence of rhythms of the first type. Constant dilution, bioproduction cycles caused appearance of rhythms of the second type. Rhythms of the third type are connected with cycles of dilution and solution. Rhythms of the fourth type are caused by cycles of dilution, solution and bioproduction. "Black shale" cyclicity occurred due to solution and dilution cycles. The nature of Middle-Upper Cenomanian limestone-marl rhythms is connected with precession cycles. Middle-Upper Cenomanian includes 47 precession rhythms versus 107 rhythms in Western Europe because of gaps in the succession. Tectonic agent is responsible for the disappearance of rhythmicity near Cenomanian-Turonian boundary in Selbuhra section. Tectonic force leds to the occurence of con-sedimental slip-slides in the Late Cenomanian.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado