Flysch Character of the Upper Jurassic-Cretaceous Formation of the Caucasus Marginal Sea Eastern Basin and Some Issues of its Origin

摘要

Study of origin of flysch sediments globally spread in the Earth's mobile belt is an actual issue of geological science. As a result of lithological study of the Upper Jurassic-Cretaceous flysch formation of the Caucasus marginal sea eastern basin two main grain-size groups of rocks characteristic of these sediments are established - phaneromere (psephitolites, psammitolites, aleurolites) and background - rhythmic alternation of cryptomere pelitolites, argillo-carbonaceous and carbonate silt expressed in recurrence of rocks with less changeable composition and different thickness (from one thousandth of centimeter to 10-12m). The rhythm begins with comparatively coarse-grained sedimentary deposits that are replaced by fine-grained formations in ascending order and are terminated by the background ones - pelitic. Sedimentation of the studied Upper Jurassic-Cretaceous flysch formation of the Caucasus marginal sea eastern basin took place mainly due to turbidite-forming suspension flows that formed spasmodically by gravitation, earthquakes and fluctuations of the World Ocean level and was also affected by climatic processes, sea currents, seismic events, dynamics of the basin, etc.The studied flysch formation evolved in the definite zone of sedimentary basin characterized by less stable hydrodynamic and unstable, peculiar hydrochemical conditions. At the same time in the basin normal marine sediments were developed. Thus, Upper Jurassic-Cretaceous flysch formation of the Caucasus marginal sea "Eastern Basin" (within the limits of Georgia) occurred due to tectonic and eustatic factors in controlled trough conditions.