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Structural Study of the Northern Edge of the Guárico Sub-Basin, Guarico State, Venezuela


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 Central Interior Range.

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 Central Interior Range in the Pliocene is proposed.