Evolución paleoambiental de la formación cubagua (Península de Araya) a partir de patrones de distribución de morfogrupos de foraminíferos bénticos

the objective of this work is to define the morphologic distribution of the benthic foraminifera of the cubagua formation, araya peninsula (eastern venezuela). within the paleoecologic study, a total of eight morphogroups were determined by the shape of the test: plano-convex and round biumbilicade, adapted to high o2 and energy environments belonging to a neritic depth; cylindrical, adapted to conditions of low energy and oxygenation (bathyal environments); spherical/ovoid and miliolina, with a variable dominion that oscillates between disoxic and oxic environments between bathyal to external neritic depths; biconvex, related to a softer substrates and euribatic conditions; conical and conical-flattened, associated to conditions of low oxygenation and diverse depths like the previous one. from the analysis q, three morphologic assemblages were : biofacies (i), determined by the dominion of the morphogroups biconvex, spherical/ovoid and cylindrical, next to the association cyclammina cancellata, chillostomela ovoidea, sphaeroidina bulloides and rectuvigerina lamellata. biofacies (ii), corresponding to a greater abundance of the spherical/ovoid and round biumbilicade group and the disappearance of spherical/ovoid and conical-flattened morphogroups, the fossil assemblage of these biofacies are globocassidulina subglobosa, bulimina marginata and plectofrondicularia floridana. biofacies (iii), responds to the greater abundance of plano-convex and round biumbilicade morphogroups and to the set hanzawaia concentrica, amphistegina lesonii, elphidium poeyanum and buliminella elegantísima. the cubagua formation sequence begins in the late miocene in bathyal environments defined by a tectonic calm, suboxic conditions and temperatures of 5oc in average. later, a bathymetry change to a external shelf environment showed temperatures between 15 and 22oc. the final sedimentation of this formation took place in the early pleistocene with sedimentation between internal shelf to reef