Rasgos Geoquímicos de las Calizas de la Formación Arroyo Verde (Eoceno), en Punta Colorada. Provincia de Río Negro. Argentina: Reconstrucción Paleoambiental

the fast growing cement industry has reactivated the exploration for calcareous materials in southern argentina.a carbonatic deposit is found in punta colorada, located 36 km from the town of sierra grande, río negro province. these rocks, deposited during a late cretaceous - early tertiary marine ingression, belong to arroyo verde formation (early eocene). these coastal deposits have been studied since 1927 by wichmann, arnolds (1952), de alba (1964), weber (1983) and busteros et al. (1998). rossi de garcía and levy (1982) assigned these rocks to the eocene; spalletti et al. (1993) located them within the roca formation (rocanense ingression) and gelós et al. (1992) correlated these rocks with arroyo verde formation (malvicini and llambías, 1974). arroqui langer et al. (2006) from sedimentologic, geochemical and lithologic data in carbonatic rocks of the precordillera argentina established an exploration and exploitation pattern. bonuccelli (2006) made a similar technical study in punta colorada, where 14,806,106 tn of measured reserves and 1,799,174 tn of indicated reserves were determined in a carbonate of less than 4% mgo grade. the study area comprise 800 ha divided in two zones separated by arroyo las palmas gully and located at the north and at the south of a basement outcrop denominated punta colorada, in the atlantic marine coast (fig. 1). by means of 12 drills cores and 8 stratigraphic profiles, a thickness of 10 m was determined for the limestone. major and minor chemical elements were determined by icp-ma in 100 ml with two replicas in alex steward laboratories, mendoza. the criterion of tucker (1981) was used to classify the limestones by the dolomite percentage. from stratigraphic profiles four levels composed of cross-bedded massive to granular fosiliferous limestones were determined. microscopically they are composed of a fossiliferous limestone (bioclastic packstone) with bivalves, equinoderms, corals, foraminifera and algae, being algal buildups mo