Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
American Association of Petroleum Geologists Annual Meeting, Dallas, April 18-21, 2004
Use of Biostratigraphic Data in the Definition of the Geological Framework of the Neogene in the Southern Laguna Madre-Tuxpan Continental Shelf, Eastern Mexico
Edgar H. Guevara, Héctor F. Ruiz-Ruiz, William A. Ambrose, Julieta Martínez-García, Juan Rico-Pérez, Tim F Wawrzyniec, Mario Aranda-García, Khaled Fouad, Shinichi Sakurai, and Luis Sánchez-Barreda
Hydrocarbon exploration in Tertiary siliciclastics in the southwestern Gulf of Mexico (GOM) has highlighted the importance of biostratigraphic studies in defining the geological setting of this relatively poorly known area. This presentation shows examples of how foraminifera and calcareous nannoplankton data help to define the stratigraphic framework of the Neogene in the continental shelf between the Veracruz and Burgos Basins in Eastern Mexico. The paleontological information constrained the age and helped in paleoenvironmental interpretations of regional intervals defined by sequence boundaries (unconformities) and maximum flooding surfaces delineated in integrated seismic and well data analysis. The studies form part of joint Bureau of Economic Geology-Pemex Exploración y Producción investigations of Neogene hydrocarbon plays in this area.
The assigned ages were based on species extinction (downhole first appearance) and/or planktonic foraminifera and calcareous nannoplankton biozone tops. Benthic foraminifera were used in paleobathymetry interpretations. Key fossils for age determinations included Discoaster brouweri, Sphenolithus abies, Globigerinoides obliquus extremus, and Globorotalia margaritae margaritae in the Pliocene; Sphaeroidinellopsis disjuncta, Globorotaloides variabilis, Discoaster quinqueramus, and Discoaster berggrenii in the Late Miocene; Globorotalia mayeri, Globorotalia fohsi s.l., and Discoaster hamatus in the Middle Miocene; and Globigerinoides bisphericus, Catapsydrax dissimilis, and Sphenolithus dissimilis in the Early Miocene.
Integration of these results with those of coastal and offshore basins in Eastern and Southeastern Mexico will result in unified biostratigraphic criteria for age and bathymetric interpretations of the Neogene in the southern GOM. This will further lead to an understanding of the stratigraphy of this underexplored interval in this region.