Isótopos del carbono y oxígeno y el origen de las calizas de las sierras de Pie de Palo y Zonda, provincia de San Juan.

LINARES, E.; VALENCIO, S. A.; PANARELLO, H.O.; GARCÍA, C. M.

Revista de La Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 1982 vol. XXXV p. 80 - 90

The present paper is based in the carbon and oxygen isotopic composition oflimestones, and the possibility of recognizingtheir depositional environment, and also, the feasibility of using the isotopiccomposition for the geological correlationof carbonatic rocks. In this particular case, it is intended to find out the origin ofthe limestonesand dolostones coveringthe metamorphic basement in the western slopeof the Sierra de Pie de Palo ( Argentina) . These rocks wereassigned to thePrecambrian by some authors, and to the Lower Paleozoic by others. Asa contributionto clarify its origin, 74 isotopicanalysis were carried out. The analyzed samples belong to theSierra Chica de Zonda ("Calizas Zonda") of marine origin; to crystalline limestones intercalatedin the metamorphic basement of the Sierra de Pie de Palo ("Calizas Cristalinas") ; and to the limestones anddolostones outcroping on the western slope of the last orographic unit("Calizas Pie de Palo"). Using statistical methods it was found out that the "Calizas Zonda" and the "CalizasPie de Palo" have similar isotopic composition, and different than the "Calizas Cristalinas". This result suggests a similardepositional environment for the formers. The d18O values of the "CalizasPie de Palo"and the statistical values found for the Cambro-Ordovician lapse, are coincident.