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vol.40 número1Sedimentología y estratigrafía de la Formación Vaca Muerta (Tithoniano-Berriasiano) en el área del cerro Domuyo, norte de Neuquén, ArgentinaRol del clima y la tectónica en la evolución geomorfológica de los Andes Semiáridos chilenos entre los 27-32°S índice de autoresíndice de materiabúsqueda de artículos
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Andean geology

versión On-line ISSN 0718-7106

Resumen

GUTIERREZ, Néstor M; HINOJOSA, Luis F; LE ROUX, Jacobus P  y  PEDROZA, Viviana. Evidence for an Early-Middle Miocene age of the Navidad Formation (central Chile): Paleontological, paleoclimatic and tectonic implications. AndGeo [online]. 2013, vol.40, n.1, pp.66-78. ISSN 0718-7106.  http://dx.doi.org/10.5027/andgeoV40n1-a03.

The age of the Navidad Formation in central Chile has always been controversial, mainly due to the conflicting age ranges indicated by its macro- and microfossils. Macrofossils are generally interpreted as having been reworked from older, Early to Middle Miocene strata, whereas a Late Miocene-Pliocene age has been accepted on the basis of planktonic foraminifer index species. The results of this study, however, indicate that the macrofossils occur in situ, which necessitates a complete revision of the geochronological data. It is concluded that the evidence for an Early to Middle Miocene age is overwhelming, and that the planktonic foraminifer index species must have appeared in the SE Pacific earlier than elsewhere. These include Globoturborotalia apertura, Globorotalia puncticulata (Deshayes), Globorotalia spheriomizea (Walters), Neogloboquadrina pachyderma (Ehrenberg), and Neogloboquadrina acostaensis (Blow). An Early to Middle Miocene age for the Navidad Formation correlates well with a reinterpretation of its depo-sitional environment as a continental shelf instead of a deepwater continental slope, global and regional paleoclimatic events, and the tectonic development of the Andes Range.

Palabras clave : Foraminifer index species; Middle Miocene Climatic Optimum; Andean tectonics; Arid Diagonal.

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