Geology Reference
In-Depth Information
The main ground water components of the Middle Pliocene are chlo-
rine and sodium ions. Their content in some cases exceeds 90%. Waters
of the upper section also include calcium and magnesium chlorides and
hydrocarbonates. Those, however, are encountered in subordinated con-
centrations. An important component of the ion-salt composition in the
alkaline water-saturated intervals is sodium hydrocarbonates. Their con-
tent reaches maximum (50%) in the base formations of the section.
Variations in the ion composition show that the contents of the chlorine,
sodium, calcium and magnesium directly correlate with the total salin-
ity, whereas the total alkalinity is in the inverse correlation with the total
salinity.
Down the section over the local structures' crestal areas, the calcium
and magnesium absolute and percentage content decreases and the car-
bonate content clearly increases (Figures 2.4-2.7). Together with these
changes the secondary salinity factors decrease, the primary alkalinity, the
total salinity drop (Figure 2.8) and hard waters turn into the alkaline ones.
The lower boundary of the chlorine-calcium type waters is stratigraph-
ically and physically highest in the Central Apsheron fields (Balakhany-
Sabunchi-Ramany - Surakhany). From this area, down the regional dip
and in the direction of weakening faulting of the local structures the alka-
line water stand level in the sections regularly lowers up to the NKP and
Figure 2.4
South Caspian Depression. Hydrochemical profiles over the crests of the
Apsheron Peninsula local structures.
