Biostratigraphy of Neogene Sedimentary Succession in the Macuspana Basin, Southern Gulf of Mexico

Narváez, Yanina¹, Javier Helenes¹, José Manuel Del Moral-Domínguez², Víctor Manuel Martínez-Morales² (1) Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, Mexico (2) PEMEX, Región Sur, Laboratorio de Paleontología y Petrografía, Mexico

Neogene strata in two wells from the southern of Gulf of Mexico were examined for calcareous microfossils. The onshore part of studied basin includes shallow marine clastic sediments with few microfossil markers within a complex structural setting. Calcareous nannofossil and planktonic foraminifera results presented here increase the definition and resolution of the Neogene biostratigraphic framework in the basin. Ages were assigned on the basis of last occurrences (downhole first appearance) of calcareous nannofossil and planktonic foraminifera events. Benthic foraminifera biofacies and calcareous nannoplankton paleoenvironment analysis were used in paleobathymetric interpretations. Index fossils for age determinations included following taxa: Calcidiscus macintyrei (Pleistocene to Pliocene), Sphenolithus abies and Reticulofenestra pseudoumbilicus (Early Pliocene), Discoaster quinqueramus and Discoaster berggrenii (Late Miocene), Globorotalia obesa, Globorotalia mayeri and Sphenolithus heteromorphus (Middle Miocene). Combination of paleontological and wire log data allows the definition of more than one stratigraphic sequence and third order cycle. Our data indicates a depositional hiatus in the late Miocene to Pliocene interval. Biostratigraphic integration of diverse wells of this sedimentary basin will help clarify the regional chronostratigraphic framework. This framework will surely help model the geologic evolution and hydrocarbon exploration in Neogene intervals from southeastern Mexico.