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Abstract: Tectono-Stratigraphic Evolution of the Eastern Maturin Foreland Basin (Eastern Venezuela)

A. Azavache, J. Flinch, G. Giffuni, R. Martinez, S. Mata, V. Mitacchione, J. G. Pereira

The Eastern Venezuelan Basin is a classical foreland basin related to the loading of the Serrania del Interior thrust-sheets. The flexure of the basin started during Upper Oligocene-Lower Miocene time and is evidenced by a major unconformity between the Cretaceous and the Lower Miocene Oficina Formation (Basal Foredeep Unconformity).

The sedimentary-filling of the Basin commences with coastal transgressive sandstones of the Oficina Formation (Lower Miocene) that constitute the main reservoir of this petroleum province. The overlying deposits of the basin can be subdivided into:

1. Deep-water stage represented by the upper Oficina shales and the Freites Formation in the south and the Carapita Formation in the north (Middle Miocene). This shale interval constitutes the main seal of the region. This stage is characterized by major onlap and a major flooding surface.

2. Progradational stage characterized by shelf-slope deposits of the Lower-Middle La Pica Formation (Upper Miocene). Siliciclastic shelf wedges consisting of deltaic facies.

3. Aggradational stage fluvial-alluvial delta plain deposits represented by the Upper La Pica, Mesa and Las Piedras Formations (Pliocene-Pleistocene).

In the northern part of the basin, southward-vergent thrusting deformed the basement and its thin Cretaceous-Lower Miocene cover. South of the Rio Tigre area compressional structures are combined with normal faults related to flexural extension. The boundary between basement-involved thrusting and flexural extension controls the type of structural traps within the basin.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela