Field Studies of the Structure of Sedimentary Strata of the Northern Part of the Vityazevskaya Bay-Bar
The structure of the sedimentary strata of the Anapa bay-bar reflects the conditions and dynamics of its formation and is peculiar for each of its constituent parts. An analysis of the structure of the upper part of the sedimentary strata of this bay-bar makes it possible to understand the sequence of its formation. A different combination of prevailing factors contributed to the complex and heterogeneous structure of the deposits of the Vityazevskaya bay-bar (part of the geosystem of the Anapa bay-bar). Field studies included the laying of pits in the main morphological zones of the transverse profile of the accumulative body, and the drilling of wells by a hand drill. The description and analysis of the deposits exposed by pits and boreholes in various morphological sections of the bay-bar revealed a number of regularities. In the lower part of the sequence, coastal-marine deposits predominate. These are mainly poorly-sorted beach deposits. The composition is diverse and is represented by unsorted sands with shell interlayers, inclusions of pebbles and algae. The role of the pelitic fraction increases with depth. Below the water-table, the deposits are dark gray with inclusions of small shells. The upper part of the sedimentary sequence is composed mainly of well-sorted eolian sands. Characteristic is the presence of a layer with traces of soil formation at the junction of marine and eolian deposits. The structural features of the sedimentary sequence confirm that the accumulative form of the Vityazevskaya bay-bar was formed under the predominant influence of coastal-marine hydro-lithodynamics processes. The presence of traces of soil formation at the boundary of beach and eolian deposits indicates that the formation of dunes occurred much later than the formation of the accumulative body of the bay-bar. Liman shore, composed of coastal-marine deposits, continued its development in the conditions of lagoon sedimentation.