AbstractPlatform carbonate formations in various climate zones differ with respect to not only composition and structure of the composing rocks and but also the internal structure of rock sequences. Rock formations in humid zones are composed mainly of the biomorphic and bioclastic limestones. Vertical sections of formations are relatively heterogeneous. The composition and structure of formations are relatively constant over the area. Formations in the arid zone are distinctly dominated by dolomites; gypsums and anhydrites are subordinate; and limestones are optional. The vertical section of these formations is differentiated: dolomite and dolomite–sulfate bands intercalate with limestone bands. The spatial distribution of rocks and formations underwent fundamental changes. In proximal zones of the sources of seawater with the mid-oceanic salinity, the sections are relatively heterogeneous and composed of limestones; dolomites prevail in the distal zones; and the section is strikingly heterogeneous. Differences in the formation composition also define the composition of oil-and-gas reservoirs at both regional and local scales.