Oksana Ivanovna Khryashchevskaya1, Evgeniy Jurevich Baraboshkin2
(1) Dept. Regional Geology and Earth History, Geological Faculty, Moscow State University, Moscow, Russia
(2) Dept. Historical and Regional Geology Geological Faculty Moscow State University, Moskow, Russia
ABSTRACT: Sequence Stratigraphy of Hauterivian - Barremian Deposits in the Central Part of Scythian Platform (Northern Caucasus)
The depositional model of Hauterivian and Barremian sedimentation is based on the detailed investigation of outcrops in Northern slope of Caucasus and boreholes in eastern part of Scythian Platform. The succession is represented by terrigenous sediments (up to 500m), which were subdivided into four formations. Each of them coincides with system tract of the same sequence. The lower Korinsk Formation (Acanthodiscus radiatus ammonite Zone) consists of clays and silts. It was formed during fast sea-level rise and continues latest Valanginian transgression. The sea transgressed onto different structures and moved in the northern direction. The following Argudan Formation (Crioceratites nolani Zone) consists of sandstones with silty detritic and oolitic limestones. The deposits are distributed wider and indicate higher sea-level. Several significant hardgrounds and / or erosional surfaces are developed at the top of the Formation. The event coincides with Lower / Upper Hauterivian boundary. The Baksan sandstone Formation (Speetoniceras inversum Zone) was formed during the high stand and it covers the largest area. The Urukh Formation (Craspedodiscus discofalcatus Zone, Uppermost Hauterivian - Barremian) consists of obliquely laminated oolitic sandstones and limestones with insignificant disconformities. It was formed under regressive conditions in a shallow basin with active hydrodynamics. This phase was finished in the late Barremian, when the condense sections and avandeltaic facieses were formed at the same time. The coarseness of terrigenous material increases north- and westwards in each system tract where, as we suggest, the land has existed. The character of sea-level fluctuations is similar to the eustatic curve.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado