Geology Reference
In-Depth Information
are listed on saturated fresh meteoric waters exposed on the surface, on
the Upper Oligocene-Lower Miocene high-permeability reservoirs (La
Roca Formation) in the Bolivar zone fields (Lagunillas, Kabimas, Tijuana,
Pueblo Vieja and Bochaquero) and on the Eocene intervals in the Las
Cruces, Boscan, Encenada and Mene Grande fields (Dickey and Hunt,
1975; Kartsev, Vagin and Matusevich, 1986; Smith, 1931).
Illegitimacy of regional hydrodynamic conclusions using so selective an
information base is obvious. The proofs of this thesis are:
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First, the listed fields are no good for characterizing hydroge-
ology of the internal basin as they are located over the flanks
of the depression next to the framing mountains where thick
sandstones of the stated intervals are substantially exposed
and are almost ideal water receivers.
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Second, within field structures themselves the same intervals
are often exposed, partially denuded or cut by stratigraphic
and formational unconformities. This creates especially
favorable conditions for the penetration into these struc-
tures of infiltration agents not only from the regional charge
area but also directly within the limits of local structures.
We believe that it is incorrect to expand this infiltration-
favorable local hydrogeological situation onto the entire
stratigraphic volume and area of the depression. To do that,
it would be necessary to account for its step-block structure,
to account for the effect of fault-blocking of the assumed
water flow by high-amplitude faults running parallel to the
mountains and to account for drastic lithofacies and forma-
tion variability of the section (Geologic structure…, 1959;
Miller, Edwards and Walcott, 1961).
Other regional factors substantially limiting the infiltration are:
t
The removal of large amounts of meteoric water from the
water-exchange through draining by a profound river net-
work (Apon, Palmar, Santa Ana, Rio Negro, Tacuco, Tarra,
Lara, Rio Bravo, Catatumbo, Escalante, Sulia, Chama,
Tucana, Caparo, Tamare and other rivers).
t
Rugged topography.
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Descending water-sources.
t
Increase in horizontal hydraulic resistance to infiltrates'
migration downdip with increased migration distance.
