Geology Reference
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a general alkaline nature of the recent metamorphism for the chlorine-cal-
cium waters of the ancient hydrochemical background. The most impor-
tant latter two mechanisms provided for drastic desalination of the source
water medium and for introducing into this medium additional amounts
of carbonate, bicarbonate, sulphate and sodium ions which facilitated the
eventual formation of the hydrocarbonate-sodium waters.
A significant additional factor was the entrance into the water-satu-
rated rocks of substantial depth-generated СО
2
volumes through a large
Anastasyev fault (cutting lengthwise the trough's axial portion), through
the contact zones of diapirs and through mud volcanoes' eruption appa-
ratus within the local structures. This process intensified formation of
the alkaline waters. The normal leaching of mineral associations in the
stated complexes worked in the same hydrochemical direction. It was a
result of syndepositionally eroding and redepositing into the Cenozoic
basins the destruction products of Early Mesozoic magmatic rocks in the
Mountainous Crimea and Caucasus major.
Thus, we substantiated the syngenetic presence in the Cenozoic com-
plexes of the chlorine-calcium waters and clearly epigenetic nature of the
alkaline waters. This determines the origin of the “transitional” sulphate-
sodium and chlorine-magnesium varieties usually forming concentric bands
around local areas of the negative hydrocarbonate-sodium hydrochemical
anomalies. This origin was a result of mixing in varying proportions of
hard waters with the ultra-alkaline waters injected from the Mesozoic. The
interaction of both stated components causes the formation of intermedi-
ate formation waters replacing one another from structural crests to the
periphery as follows: “transitional” hydrocarbonate-sodium - “transitional”
sulphate-sodium - “transitional” chlorine-magnesium - “transitional” chlo-
rine-calcium - background chlorine-calcium. As the water types replace one
another, their total salinity increases in the same direction. Initially, from the
anomalous areas, it is accompanied by the decline in the primary alkalin-
ity factor, but then, with the approach to the oil-water contact, by a gradual
increase in the secondary salinity factor to maximum background values.
Modeling of mixing indicates that the content of the ecdemic alkaline
component in the Paleocene-Lower Eocene formation waters is up to
95%; in the Upper Eocene formation waters, 86%, in the Oligocene-Lower
Miocene formation waters, 83%, in the Middle-Upper Miocene formation
waters, 65% and in the Pliocene formation waters, 60%.
The process of mixing is supported also by the areal and vertical dis-
tribution of the sulphate ion. Its maximum content in the Cenozoic water
complexes is recorded only within the negative hydrochemical anomalies
and gradually decreases toward the oil/water contact. The probability of
