Abstract

SILVA ARIAS, Alejandro; MANTILLA FIGUEROA, Luis Carlos  and  TERRAZA MELO, Roberto. CHEMICAL CLASSIFICATION AND GEOTERMOMETRY OF CHLORITES FROM THE CRETACEOUS SANTA ROSA AND LUTITAS DE MACANAL FORMATIONS, EASTERN EMERALD BELT, EASTERN CORDILLERA, COLOMBIA.. bol.geol. [online]. 2010, vol.32, n.2, pp. 45-54. ISSN 0120-0283.

The study of the chemical composition of chlorites from the Santa Rosa and Lutitas de Macanal Formations in the Eastern Emerald Belt (Eastern Cordillera), are used to estimate the formation temperature of these minerals and the associated hydrothermal fluids. The chlorites were analyzed using the classification proposed by Hey (1954), Foster (1962), and Bailey (1980); and the formation temperature is calculated from empirical geothermometers from Kranidiotis and MacLean (1987), Cathelineau (1988), Jowett (1991) and Xie et al. (1997). Chlorites in hydrothermally altered rocks associated with emerald mineralization of the Santa Rosa Formation is classified as clinochlore and formed at temperatures of ~354°C, this temperature is consistent with the fluid inclusions in emeralds of the same formation. Chlorites in veins from Lutitas de Macanal Formation are classified as chamosites and formed at lower temperatures between 210-225°C.

Keywords : Eastern Cordillera; Chlorites; Eastern Emerald Belt; Geotermometry.