Extension and limits of the Choromoro and Aconquija Groups in the Tucumán-Santiago plain

Abstract

?The extension and limits of the Choromoro and Aconquija Groups in the Tucumán-Santiago plain?. The tertiary stratigraphic succession in the Province of Tucumán (Argentina) is formed by the Miocene Choromoro and Aconquija groups. The first one has an extense surface with the outcrops which lean against the eastern slope of the Cumbres Calchaquíes. These outcrops, almost unseen towards the South, appear underlying in the plain to become visible in the provinces of Santiago del Estero and Catamarca. In the Aconquija group the outcrops limit with the South-eastern sector of the homonimous Sierra. The studied perforation show the limits between both complexes. The transversal geologic profile of the Tucumán-Santiago plain includes the blocks of metamorphic basament towards the East. They deepen to become visible again in the Sierra de Guasayán, towards the East. The sedimentary deposits of the Late Tertiary lie on these meridionally fractured blocks. Their thickness is about 2,000 meters, already in the plain. The study of perforation ?being the deepest one of 804 meters thick? allows to see te repetition of the levels from the Tertiary which is considerated to be the result of the fracture intensity. Along the whole profile the recurrence of the Tertiary basament is the contrasting characteristic in the comparison to what is happening at the austral extreme of the Northeast of Tucumán mountains and the oriental area of the Sierra de Guasayán.