Showing papers on "Ankerite published in 1980"

Isotope composition of carbon in the carbonates of the Gumbeykan scheelite deposits in the southern Urals

Abstract: Through investigations of the isotope composition of carbon of various generations and carbonates from marbles, skarns, and nested and vein scheelite orebodies, the probable source of carbon of these carbonates has been established as a mixture of sedimentary carbonates, carbon dioxide with carbonic acid that was formed by oxidation of the organic matter from sedimentary terrane (..delta..C/sup 13/ - 0.05 to -0.62%). In the calcite and dolomite phenocrysts of marble and the coarse-grained dolostone, containing scheelite, the carbon was lighter (..delta..C/sup 13/ from -0.60 to -0.87%). For the dolomite and ankerite from scheelite pockets of the Balkan deposit and quartz veins of the Buranovo, ..delta..C/sup 13/ varied from -0.44 to -0.87%. The lightest carbon found in strontianite (..delta..C/sup 13/ = -1.32%), located near the coating of the organic matter (..delta..C/sup 13/ = -1.26%) in fractures of the quartz vein of the Buranovo deposit. In the section through the orebodies and near-ore diffusion-metasomatic zones of the Balkan deposit, the lessening of carbon in the carbonates was observed, with increasing distance away from the fracture. ..delta..C/sup 13/ in the altered granitoids ranged from -0.44 to -1.03%; while in the diopside-wollastonite hornfels, from -0.89 to 1.13%. The lessening in weight of the carbonmore » is explained by diffusional fractionation of the isotopes caused apparently by the differential movement of volatile mixtures of carbon during ore-forming processes and the formation of their diffusion-metasomatic zones.« less