Abstract

GARRIDO, Alberto C.. Stratigraphy of the Neuquén Group, Upper Cretaceous of the Neuquén Basin (Argentina): new proposal for lithostratigraphic ordaining. Rev. Mus. Argent. Cienc. Nat. [online]. 2010, vol.12, n.2, pp.121-177. ISSN 1853-0400.

The Neuquén Group conform a succession of non-marine deposits of fluvial, aeolian and shallow lacustrine origin, developed in the Neuquén Basin between the Lower Cenomanian and the Middle Campanian (Upper Cretaceous). This succession reaches 1,200 m of maximum thick, being bounded at the base and the top by the Patagonidican and Huantraiquican unconformities respectively. In this paper two new formations are proposed (Los Bastos and Sierra Barrosa Formations, nom. nov.), and the subgroups were reconfigurated. Consequently, the Neuquén Group is composed lithostratigraphically by three subgroups and nine formations. The Río Limay Subgroup comprehend the Candeleros and Huincul Formations, representing low sinuosity channel deposits developed under tectonic and climatic subordinated control. The Río Neuquén Subgroup comprehend to the Cerro Lisandro, Portezuelo, Los Bastos, Sierra Barrosa and Plottier Formations, conforming a psamitic and pelitic interstratified succession of fluvial origin, mainly developed under climatic control. Finally, the Río Colorado Subgroup integrated by the Bajo de la Carpa and Anacleto Formations, comprehend fluvial deposits developed under a new dominant tectonic control. At the start of the deposition of the Neuquén Group, the Dorsal de Huincul worked as a structural high, generating toward the south of the Neuquén Basin one a small endorreic depocentre corresponding to the Picún Leufú Sub-basin, scheme that would have been keep up to ends of the deposit of the Candeleros Formation. During the rest of the deposit of this sequence, the drainage would have been kept without major modifications towards the pacific slope across a central collector flowing in sense N-NW. Towards the end of the deposit of the Neuquén Group takes place the inversion of the regional slope of the basin, making possible the ingression of the Atlantic Ocean and the beginning of the deposition of the Malargüe Group.

Keywords : Neuquén Group; New lithostratigraphic units; Upper Cretaceous; Neuquén Basin; Argentina.

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