Historically, it is believed that crystalline uraninite, produced via the abiotic reduction of hexavalent uranium (U(VI)) is the dominant reduced U species formed in low-temperature uranium roll-front ore deposits. Here we show that non-crystalline U(IV) generated through biologically mediated U(VI) reduction is the predominant U(IV) species in an undisturbed U roll-front ore deposit in Wyoming...

introduction two main principal aspects for the genesis of porphyry copper deposits have been determined. the first genetic model concerns the petrologic and geochemical processes and the other relates the genesis to crustal deformation and geodynamic conditions (kesler, 1997). recent studies (e.g., padilla garza et al., 2001) show that the generation and emplacement of porphyry copper deposits...

New U-Th-Pb zircon data (SIMS) from three intrusive phases of the Palaeoproterozoic Viterliden intrusion in the western Skellefte District, central Fennoscandian Shield, dates igneous emplacement in a narrow time interval at about 1.89 Ga. A locally occurring quartz-plagioclase porphyritic tonalite, here dated at 1889± 3 Ma, is considered the youngest of the intrusive units, based on the new ag...

Purpose. Determination of the features formation gold mineralization within Bakyrchik ore field and influence deep intrusive rocks on bodies. Methodology. Analysis literature data, interpretation geophysical studies, work laboratory studies mineralogical composition bodies dikes Kunush complex (ISP-MS ‒ Agilent 7500cx), study main types mineral associations zone alteration (JSM 6390LV)). Findin...

The term "Carlin-type" deposit has been applied to a number of low-grade, sedimentary rock-hosted gold deposits that have been discovered and brought into production in the western United States since the 1960s. Carlin-type deposits are characterized by replacement of carbonate and silty carbonate rocks by silica, pyrite, barite, various arsenic, mercury, antimony, and thallium minerals and by ...

The selection of the most appropriate underground mining technology is not a simple process because it involves handling large amount information about several potential methods. Multicriteria optimization approaches are proven useful tools for ranking alternatives, especially in cases where multiple complex criteria have to be considered simultaneously. An ore deposit system its geology, physi...