Las principales discordancias del Mesozoico de la Cuenca Neuquina según observaciones de superficie

• Autores: Héctor Leanza
• Localización: Revista del Museo Argentino de Ciencias Naturales, ISSN-e 1853-0400, ISSN 1514-5158, Vol. 11, Nº. 2, 2009, págs. 145-184
• Idioma: español
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• Resumen

  • The main unconformities of the Mesozoic of the Neuquén Basin based on surfaceobservations. A general summary of the main unconformities which produced major order break-ups duringthe evolution of the Mesozoic sedimentary infill of the Neuquén Basin is offered in this paper. Based on itshierarchy, they are categorized in three groups, as follows: 1) key unconformities widely spread along the wholebasin; 2) «Intracuyan» unconformities related to the Dorsal de Huincul, and 3) «Intraprecuyan» unconformitiesrestricted to isolated depocentres. Having into account tectonic, eustatic, paleoclimatic and/or paleontologicalaspects of the sedimentites situated below- and above of each unconformity, precisions about their ages aregiven. The number of the recognized key unconformities sums 10, as follows: Huarpican (Intratriassic),Rioatuelican (Intraliassic), Lotenican (Intracallovian), Araucanican (ca. Oxfordian/Kimmeridgian boundary),Huncalican (Intravalanginian), Coihuequican (Intrahauterivian), Pampatrilican (Intrabarremian),Pichineuquenican (Intraaptian), Patagonidican (ca. Albian/Cenomanian boundary) and Huantraiquican(Intracampanian). In relationship with the area realated with the Dorsal de Huincul, three «intracuyan»unconformities were identified, as follows: the Intratoarcian, only recognized at subsurface, the Seguelican(Intrabajocian 1) and the Lohanmahuidican (Intrabajocian 2). However, the influence of these unconformitiesdiminish towards northern areas of the basin, as the distance increase with regard to the cited morphostructuralelement. The «intraprecuyan» unconformities recorded in the Cordillera del Viento and Chachil depocentresare of local character and less hierarchy. They are the result of short interruptions in the volcano-sedimentaryinfill of these halfgrabens. Given its geographical restriction to the cited depocentres, no formal names wereascribed to these unconformities. Once defined the key unconformities, a summary in three tables of geneticallyrelated formational units bounded by them, using the classical lithostratigraphic categorization in Groups, thelatter ones basically coincident with the concept of tectosedimentary units (TSU), is presented. The obtainedresults lead to suggest some new ideas with regard to the evolution of the Neuquén Basin and to keep attentionon still open nomenclatural problems.