Geology Reference
In-Depth Information
properties of the said barriers deteriorate and some water-saturated lenses
and beds appear in the section.
At present there are no actual data on the ground waters in the
Paleozoic-
Middle Jurassic
complex of the Internal Foredeep zone. As a preliminary
matter, based on general hydrogeological concepts, it may be assumed that
they are probably high-concentrated chlorine-calcium brines with total
salinity about 1,155
−
1,225 mg-equiv. (330
−
350 g/l) and secondary salinity
factor of about 20
22%-equiv.
The Upper Cretaceous - Upper Oligocene
flysh complex (the so-called
Carpathian Formation) covers a stratigraphic range Stryy Fm. (Upper
Cretaceous) - Polyanitsa Fm. (Upper Oligocene). Ground waters there
are mostly chlorine-calcium brines, 315
−
300 g/l)
salinity. At some prospects of the Bitkov area (Bitov, Pniv, Pasechnyan,
Bukhtovets) the Upper- and Middle-Menilite deposits are in contact with
the Vorotyshchen evaporites of the overlying Lower Miocene waterhead
complex. The salinity increases to 1,155
−
1,050 mg-equiv. (90
−
450 g/l) and
ground waters in the said intervals become in their hydrochemical outlook
practically identical with the salt formation waters. High water salinity
in these Lower and Middle Oligocene intervals resulted from squeez-
ing down of the Vorotyshchen brines during the Late Miocene tectonic
activity in the region when the nappe formation was going on (Glushko
et al
., 1963; Dolenko, 1962). This mechanism is supported by the fact of
the waters in the underlying Lower Menilite rocks in some fault-blocks of
the area having the same chlorine-calcium hydrochemical type but lower
salinity of up to 700
−
1,575 mg-equiv. (330
−
220 g/l). Down the section of the
area the water salinity increases again and at depths about 3,000 m (in the
Manyavsk, Vygodsk and Bystritsa Eocene formations) exceeds 1,050 mg-
equiv. (300 g/l).
The component composition of the waters in the described complex is
dominated by sodium and calcium chlorides. The sulphate-ion content
does not exceed 2
−
770 mg-equiv. (200
−
5 mg-equiv. with the tendency of downward increase.
The calcium and magnesium concentration is respectively 30
−
30
mg-equiv.; the total alkalinity is no more than 10 mg-equiv.; the Na/Cl
ratio is 0.90
−
90 and 5
−
0.95 and the secondary salinity - д
о
22%-equiv.
Together with the chlorine-calcium brines at some prospects in the
foredeep (mostly in the Menilite Series) were established, locally, chlo-
rine-calcium waters of a drastically lowered salinity (350
−
−
525 mg-equiv.
or 100
150 g/l) and chlorine-magnesium and hydrocarbonate-sodium
varieties with the salinity of 105
−
90 g/l) (Tanyava,
Spas, Lukva, Bukhtovets, Dolina, Северная Dolina, Obolon, Strutyn,
Olkhovka).
−
315 mg-equiv. (30
−
