In this model, the mficas crustais rocks, below of the Witwatersrand basin, would have been the source of the gold. 2.3. See Christie’s for more details and insights. GOLD DEPOSITS SPREAD IN ROCKS CARBONTICAS Gold spread in sedimentary rocks, of the Carlin type, constitute rich pyrite deposits in auriferous arsenopirita, epigenticos, spread, characterized for dissolution of carbonates, arglica alteration, sulfetao and silicificao in calcreas sedimentary rocks. Gold and pyrite precipitate together with rich fluids in H2S for the sulfetao of minerals of iron of the encaixantes rocks. The deposits are associates with normal imperfections of high permeveis angle and horizontes of sedimentary successions. They had been formed when fluid hidrotermais, flowing throughout imperfections, found zones of permeveis breach and/or horizontes.
The fluids then had reacted with the encaixantes rocks, producing its alteration and depositing gold. The process is essentially of selective substitution of carbonosa rock for silica, pyrite and gold. The deposits form it 1,5-4 km, with T of > 225oC. 2.3.1.GEOLOGIA LOCAL Is about detailed geologic studies of the white area of mineral research, approaching its characterizations, topographical, petrolgicas and petrogrficas, structural litoestratigrficas, (falhamentos and dobramentos, linear structures etc.), geomorfologia, draining and still hydrography. 2.3.2.JAZIMENTO Must be made a detailed description of the mineral deposit in accordance with systematics to follow, as well as describing all previously its mentioned characteristic elements: Type of rocks: hostesses, encaixantes, intrusivas; Structures: shear, imperfections, folds, etc. in relation to the ore; Mineralogy of the hostesses: description of the mineralized litotipos; Tectnica Ambincia: tectnica before, during and after the formation of the hostesses and the deposit; Age of the hostesses: ages and methods of detention; Mineralogy of the ore: cloudy and translucent minerals for occurrence way; Secondary, accessory mineralogy and of alteration: associations for alteration zones, metamorfismo and retrometamorfismo; Controls of the mineralizao: litoestratigrficos, structural controls etc.; Structures and textures of the ore: bandado, to filonar, of substitution, exosoluo etc.; Signature geochemistry: positive and negative anomalies in the area of the deposit; Fluid mineralizadores: types of fluids and its chemical compositions; Isotpica signature: isotpica composition of the rocks, minerals and fluids; Supergnica alteration: mineralogy, structures and textures of the meteoric alteration; Last production: to indicate the production and the periods of production; Esteem reserve: amounts for types of reserve (measured, indicated and inferred), texts and year; Deposits associates: other deposits in the same area or region or geologic unit; Other similar deposits: other deposits of the same type in Brazil and the world.