The northwestern Argentina Tarija Basin: Stratigraphy, depositional systems, and controlling factors in a glaciated basin Daniel Starck a, * , Cecilia del Papa b a Tecpetrol S.A., Buenos Aires, Argentina b CONICET, Universidad Nacional de Salta, FCN, Buenos Aires, 177-4400 Salta, Argentina Abstract The Tarija Basin, shared by Bolivia and Argentina, was subjected to glacial conditions during the Late Carboniferous and Early Permian. The Macharetı ´ and Mandiyutı ´ groups deposited during these times record in their facies advances and retreats of the Gondwa- nan ice cap. The lithostratigraphic subdivision of these groups presents stages with minor glacial influence in the basal formations of each group (Tupambi and Escarpment formations), whereas in the upper units, glacially related deposition prevails (Tarija and San Telmo formations). Typical facies deposited in relation to glacial settings are diamictites and mudstones mainly related to proglacial, lacustrine environments. During the stages of main ice retreat, deposition was dominated by fluvial and deltaic sandstones. Significant erosion and deep valley incision characterize the basal surfaces of both groups. Conversely, the stratigraphic surface that separates the sandy forma- tions from the overlying diamictites tends to be rather flat. The dynamics of the glacial cap are not only reflected in the facies distribution but also were a key factor in creating accommodation space; the changes in the glacial-driven subsidence linked to the advance and retreat of the ice were its main control. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Late Carboniferous; Gondwana glaciation; Tarija Basin; Northwestern Argentina Resumen La Cuenca de Tarija, compartida por Argentina y Bolivia, estuvo sujeta a la accio ´ n glacial durante el Carbonı ´fero Tardı ´o y el Pe ´rmico temprano. Los grupos Macharetı ´ y Mandiyutı ´, depositados durante ese intervalo registran en sus facies los avances y retrocesos del cas- quete glacial Gondwa ´ nico. Ası ´, la subdivisio ´ n litoestratigra ´ fica de estos grupos refleja etapas con escasa influencia glacial en sus unidades basales (formaciones Tupambi y Escarpment) mientras que en las unidades superiores de los mismos predomina la depositacio ´ n relacio- nada a glaciaciones (formaciones Tarija y San Telmo). Las facies tı ´picas depositadas mientras la cuenca fue alcanzada por los casquetes glaciares fueron diamictitas y pelitas relacionadas a ambientes lacustres pro-glaciales. Durante los estadios de retroceso de los casquetes, la depositacio ´ n estuvo dominada por areniscas de origen fluvial y deltaico. La superficie basal de cada uno de los grupos se caracteriza por presentar una erosio ´ n importante y por la incisio ´ n de profundos valles. Contrariamente, la superficie que separa las formaciones arenosas de las suprayacentes diamictı ´ticas tiende a ser bastante plana. La dina ´ mica del casquete glacial no so ´ lo afecto ´ la distribucio ´ n de facies, sino que tambie ´n condiciono ´ el espacio de acomodacio ´ n por medio de cambios en la subsidencia relacionados al peso del casquete. Ó 2006 Elsevier Ltd. All rights reserved. Palabras clave: Carbonı ´fero tardı ´o; Glaciaciones Gondwana; Cuenca Tarija; Noroeste Argentino 1. Introduction The Tarija Basin (Vilela, 1967), which straddles the present Argentina and Bolivia territories, underwent an 0895-9811/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.jsames.2006.09.013 * Corresponding author. Tel.: +54 11 40185919; fax: +54 11 40185987. E-mail addresses: daniel.starck@tecpetrol.com (D. Starck), delpapac@ unsa.edu.ar (C.del Papa). www.elsevier.com/locate/jsames Journal of South American Earth Sciences 22 (2006) 169–184