Title

S. B. Shishlov, A. V. Zhuravlev, T. S. Rodina

Composition and genesis of the shelly limestones of the Buregi Beds in the type area (fras-nian, south coast of the Il`men Lake)

The low part of the Buregi Beds is represented by shelly limestone unit consisting of 8 lithological types, which compose retrograding clinoforms – lens-like geological bodies up to 0.6 m thick and 1.5– 2.5 km width. It is demonstrated that this composition of the unit is caused by changes of the rate of the ongoing transgression. Increasing of the transgression rate led to rapid bias of the shoreline (1–2 km) and decreasing led to sedimentation in the environment of shoreward migration of the shallow-water seascapes. During the next rapid sea level rise the new clinoform was formed.
Key words: shelly limestone unit, lithological types, sequence of lithotypes, lateral facies sequence, clinoform, transgression, palaeogeography, Buregi Beds, Upper Devonian, Il’men Lake.