CORRELATION OF SECTIONS OF LOWER-MIDDLE JURASSIC DEPOSITS IN THE GREATER CAUCASUS

Abstract

Composite stratigraphic sections of Lower-Middle Jurassic (pre-Callovian) deposits, which have been studied in the northern, axial, and southern parts of the Greater Caucasus central segment are described. Stratotypes and fauna of formations and subformations distinguished in these three areas are characterized. The established sedimentation stages characteristic of the whole Jurassic basin of the Greater Caucasus are used to correlate stratigraphic subdivisions of the northern area, where their paleontological content is well studied, with corresponding units of the axial and southern parts, where paleontological data are either insufficient or unknown. As a result, ages of subdivisions in the axial and southern areas are elucidated with a great accuracy at the substage and zonal levels, although previously they have been regarded as units of a wide stratigraphic range, and some researchers even considered them as Paleozoic-Triassic but not Jurassic subdivisions. The relationship between Middle Jurassic (Aalenian-Bathonian) and overlying Callovian-Upper Jurassic deposits has also been elucidated in sections of the northern, axial, and southern area.