Preliminary studies of Devonian microfloras of a borehole from the Tarija Basin, Northwestern Argentina

NOETINGER S., DI PASQUO M.M.

4º European Meeting on Paleontology and Stratigraphy of Latin American

Instituto Geológico y Minero de España

Lugar: Madrid; Año: 2007; p. 285 - 290

Devonian deposits in the southern Tarija Basin crop out mainly in the western Subandean Range to the eastern part of the Cordillera Oriental of Argentina and are widely distributed from the northernmost of Argentina to Bolivia. In contrast, Devonian subsurface deposits extend over between Bolivia, Paraguay and Argentina. They are represented by shale and sandstone facies deposited mainly in a shallow marine environment; less significant are littoral and continental facies that contain palaeontological evidences of having been connected with other coeval close deposits in Brazil, Peru, Uruguay especially during transgressions (Fig. 1; Melo, 1989; Starck, 1996; Limachi et al., 1996). Subandean zone, in this basin is a thinskinned thrust belt characterized by elongated anticlines that run north-northeast–south-southwest, forming several continuous, and parallel ranges (Echavarria et al., 2003, and references therein). One of them is called San Antonio, where the borehole San Antonio X-1 is located. Most of the knowledge on Devonian successions from the Tarija Basin comes from subsurface data, from petroleum boreholes drilled during the pasts decades (see Limachi et al., 1996). The Los Monos Formation and its Argentinean equivalent, the Tonono Formation, range from the latest Eifelian or early Givetian through the early Frasnian (Melo, 2005 a, and references therein). This work presents a preliminary palynological survey of a Devonian microflora recovered from the Los Monos Formations in the San Antonio X-1 well in the Tarija Basin, northwestern Argentina.