Geology Reference
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enriched in deuterium (these alkaline varieties were gener-
ated mostly in Mesozoic: Rachinsky, 1972).
t
Two, there is an identified pattern of increase down the
vertical section in the ground water sulphate-ion con-
centration as a function of sulphate-containing hydro-
carbonate-sodium water invasion scale and volume into the
Pliocene section (Mekhtiyev, Rachinsky and Kuliyev, 1984;
Rachinsky and Akhundov 1968; Rachinsky, 1973; Rachinsky
and Aliyev, 1973).
The same is supported by our estimate of the geochemical age of con-
densates and oils over the West flank of the South Caspian Depression.
Using Reznikov's estimation technique (Rachinsky, 1987), the age of con-
densates in the Pliocene accumulations varies between 75 and 115 MMY,
and of oils, between 50 and 200 MMY. Comparison of hydrocarbons' geo-
chemical age shows that:
t
They are clearly epigenetic in the Middle Pliocene Productive
Sequence (age no older than 8 MMY).
t
Their stratigraphic age is identical to, and they display physi-
cochemical match with, the thermobaric conditions of the
Mesozoic interval's present-day depths (Rachinsky and
Aslanov, 1973).
Chapter 2 noted the overall similarity in all Post-Valanginian intervals
on the west flank of the South Caspian Depression between hydrocarbon-
ate-sodium, sulphate-sodium and chlorine-potassium varieties obvious
against the regional chlorine-calcium background and their consistent
association with faulted zones, diapirism and mud volcanism. This is evi-
dence of hydraulic intercommunication between all stratigraphic units
in the region's Meso-Cenozoic. This determines the scale of vertical fluid
cross-flows at 12-8 km and the unity of hydrodynamic system in the entire
section over the West flank of the South Caspian Depression. Its elements
are the Middle Jurassic-Valanginian interval (charge area) and the Post-
Valanginian stratigraphic volume (discharge area). A model of such hydro-
dynamical association may be mud-volcanic activity involving the entire
section and paroxysmally manifesting in the neotectonic processes' activa-
tion periods.
Particulars of ground water composition and spatial distribution of
salinity indicate a definitive role of fault conductivity providing for the
