--> Abstract: Stratigraphic Correlation of the El Barbasco Group, Venezuela, with Lower Paleozoic Sequences in Colombia and Algeria — A New Exploration Perspective, by Jaime A. Reyes and Juan C. Laya; #90082 (2008)

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Stratigraphic Correlation of the El Barbasco Group, Venezuela, with Lower Paleozoic Sequences in Colombia and Algeria — A New Exploration Perspective

Jaime A. Reyes and Juan C. Laya
Group to the Earth Sciences, Los Andes University, Merida, Venezuela

Within the framework of the oil exploration, Venezuelan oil company PDVSA, included the Paleozoic sequences taking like reference, important oil systems as the Province Illize in Algeria. In the surface exploration phase, Los Andes University studied Venezuelan Plains sequences, specifically in the El Barbasco Group (Upper Cambrian? - Silurian?), was revised the petrography, biocronology and the litological contacts, and obtained a new lithostratigraphic column for the Group: Cañaote Formation in the bottom, Cerrajón Formation in the middle, and Mireles Formation on the top, with ages from Middle Cambrian? to Lower Ordovician (Tremadoc).

The stratigraphy proposed for the Group allows to correlate it with the underground formations Hato Viejo and Carrizal, taking into account, among other features, feldspars dissolution and quartz cementation in burial deep diagenesis, the fluvial environments in Hato Viejo and neritic environments in Carrizal, the same as in Cerrajón and Cañaote Formation. In the underground of the Oriental Plains of Colombia, in Cambrian levels, Negritos Formation (Cambrian sensu lato) contains dark shales and quartzite sandstones of shallow marine environments. However, the presence of Jujuyaspis keidely, allows assigning a Tremadoc age to the top of the formation, and allows a direct correlation with Mireles Formation.

Finally, in North Africa (Illize Province) important sequences of the Middle to Upper Cambrian, are Hasi Messaoud and Hassi Leila formations, with sandtones and mudstones rocks, deposited in shallow marine environments. These formations are overlay by Achebyat, and Argile d'El Gassi formations of the Lower Ordovician (Tremadoc), and contains mudstones and shales, this litostratigraphic distribution is the same in the El Barbasco Group. These preliminary correlations show an interesting perspective of exploration in Venezuela.

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