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structures with higher hydraulic communication between the deeper and
shallower intervals.
This is supported by the fact that in the former group fields the waters
in productive fault-blocks are highest salinity, typically chlorine-calcium
varieties with highest secondary salinity factor and are absolutely similar
to the waters of the underlying Miocene series. In the latter group of fields
the waters of productive areas are closer to the background waters.
In other words, within productive fault-blocks of most faulted fields
there is practically no variation in ground water salinity and component
composition down the stratigraphicому section. All intervals within the
oil-water contacts are saturated with waters of identical hydrochemical
outlook. The vertical hydrochemical zoning is more contrasting on less
faulted structures.
The conclusion about the ground water cross-flows in the region is also
based on the specifics of the sulphate-ion distribution over the area and
in the sections of the local highs. Its highest concentrations in Pliocene
intervals are discovered in the waters of productive fault-blocks whereas
its content in the background water is always much lower. And maximum
sulphate content strictly corresponds with its concentration in the Miocene
waters. Also noteworthy is that maximum SO 2 amounts are identified in
the formation mixes with the maximum foreign component. The prob-
ability of the sulphate preservation as relics of the salt composition in the
Pliocene depositional basin water is low. The reasons are the transit of
deposits in the course of the subsequent geologic evolution through the
active microbial sulphate reduction zone and experimentally established
fact of its generation within the catagenesis zone (Kissin, 1967; Kononov,
1965; Krasintseva, 1968). This zone corresponds with thermobaric envi-
ronment of the Miocene complex in the Los Angeles Depression. All these
give reason to believe that the major mechanism controlling the appear-
ance and presence SO 2 in the Pliocene series waters is its invasion by sul-
phate-containing waters of a Miocene stratigraphic belonging.
Thus, the data of hydrochemistry for the Los Angeles Depression sug-
gest that the spatial distribution of ground waters in its sediment cover was
determined by interformational cross-flows from its lower to the upper
stages.
2.1.6
The Maracaibo Basin
The basin's sediment cover includes ground waters of all genetic types.
Most common are hydrocarbonate-sodium waters saturating the post-
Mesozoic stratigraphic section. The Cretaceous and underlying rocks
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