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Structural Study
of the Northern Edge of the
Polanco F, Rosa E., Universidad Central de Venezuela, Caracas, Venezuela
This is a structural interpretation from remote sensing images
(Landsat7, ERS), as well as of the data collected in the field.
The typology of the fracturation is very similar in all the
studied tectonic sets in surface, as well as in subsurface. The fracturation,
being mainly subvertical, follows certain main directions: N0-10, N45-55 and
N140-150, and another one N80-90.
Linear features of direction N-S and NNE-SSW were identified
within the basin. Some of them can be due to strike-slip faulting, whereas
others seem to be the expression of deep structures recently reactivated.
Between the found directions (Angelier’s method), a compression with ?1 between NNW-SSE and N-S stands out, with
some local variations; this phase would be the one that gave origin to the main
structures. The other phase, of probably Pliocene age, is an extension
NNW-SSE, and their evidences are more well-known in the foothills. Extension
could correspond to the beginning of a lateral collapse or “étalement”in the
The direction of the ?Hmax
in wells is quite different from the determined one in surface: N40.
That can be explained by the presence of deep normal faults with directions
between ENE-WSW and NE-SW. A flexure of the basement as a result of the
overload imposed in the N is possible.
The extensive
phase of the Pliocene seems to correspond with which it has been reported in
the middle Tuy river basin and in the Barlovento’s depression. In this case, an
isostatic rebound of the