Geology Reference
In-Depth Information
A typical feature of the complex is the commonality over the local struc-
tures of contrasting negative hydrochemical anomalies in the intensely
faulted areas (southern flank of the West Kuban trough), of the diapir
piercings and mud volcanoes (axial zone of the West Kuban trough and
the Kerch-Taman area). A typical example is the Anastasyev-Troitsk field
in the axial portion of the trough. There, in the Anastasyev area in the near-
crestal zone close to the diapir piercing and substantial faulting, in the IV
horizon of the Meothic Stage that includes the largest oil accumulation in
the region, a local zone of low-salinity water (18-20 g/l), hydrocarbonate-
sodium (factor primary alkalinity 20-30%-equiv.), with elevated sulphate
content (1.5-2.0 mg-equiv.) is clearly identified against the background of
a high-salinity (up to 43.5 g/l) chlorine-calcium water medium (secondary
salinity factor up to 5%-equiv.).
These waters are replaced toward the tectonically quieter peripheral
areas of the structure by the bands of “transitional” sulphate-sodium and
chlorine-magnesium (secondary salinity factor 0.2-1.2%-equiv.) waters of
at the same time increasing salinity, up to maximum concentrated chlorine-
calcium (secondary salinity factor 5%-equiv.) varieties outside the oil outline
(hydrochemical background) (Shaulov, Fedotova, 1975). These high-alka-
linity waters are regionally developed only in the Mesozoic deposits. This
determines a rather significant range of ground water vertical crossflows
within the subject field (the Mesozoic-Upper Miocene stratigraphic inter-
val). A similar phenomenon is also established in the Akhtyr-Bugundyr,
Abino-Ukrainsk, Kudako-Kievsk and other fields over the southern flank of
the trough (Yermovayev, Kotov and Rogoshin, 1960; Kotov, 1963) as well as
at the prospects of the Kerch-Taman area (Lagunova, 1973) where the inter-
vals in the Upper Miocene and Mesozoic are hydrodynamically connected.
he
Pliocene
complex comprises lens-shaped sandstones and loams
turning laterally into clays. They form the Ponthian, Kuyalnik and
Kimmerian Stages and Akchagyl-Chaudin horizon and are saturated
with waters of any hydrochemical type varying in salinity between fresh
(1-2 g/l) and salty (50-60 g/l). In the complex's upper portion are com-
mon fresh waters of mostly sulphate- and hydrocarbonate-sodium types.
They have infiltration originе; the salty chlorine-calcium waters in the
lower intervals are found in subsided zones of the trough remote from
the meteoric charge; they form the hydrochemical background. The
medium-salinity (26-30 g/l) “transitional” sulphate-sodium, hydrocar-
bonate-sodium, chlorine-magnesium and chlorine-calcium varieties
develop in the lower horizons. They are typical of the local bands of the
hydrodynamic contact between the infiltration and depositional waters
