Gold in Archean iron formations at the nova lima district, and in the Quadrilatero Ferrifero, Minas Gerais, Brazil

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6454616

Ladeira, E A

Gold is in iron formation and metachert of the Rio das Velhas Greenstone Belt which underwent three main periods of deformation and is greenschist facies. At the Morro Velho, Bicalho, Bela Fama, and Urubu mines gold is mostly within and at grain boundaries of pyrrhotite, arsenopyrite, pyrite, minor chalcopyrite, cubanite, tetrahedrite, galena and sphalerite, in stratiform and stratabound massive and banded sulfide bodies. Some gold is in minor quartz veins. The main host rock consist of schistose to massive quartz ferroan dolomite and ankerite and it rests on spilitized tholeiitic metabasalt with intercalcated mafic to felsic metatuffs overlain by intermediate to felsic metatuffs. /sup 18/O of authigenic quartz of 17.07 per thousand is similar to that of Archean marine carbonate-bearing chert. At the Raposos, Faria, Cuiaba, Sao Bento and Santa Quiteria mines gold is with sulfide minerals similar to those at Morro Velho Mine but is in banded, cabonate, silicate, oxide and sulfide facies iron formation conformable upon and lateral to carbonate rock which both overlies and is intercalated with spilitized pillowed metabasalt, felsic metatuffs and graphitic phyllite. Both gold bearing-sections have a base of metamorphosed periodtitic komatiite and basalt and clastic rocks. The gold-bearing sulfide bodies, the carbonate rock and the BIF are interpreted as chemical precipitants on the sea floor by mixing of ascending reduced hot aqueous fluids and sea water.

• Research Organization: Instituto de Geociencias Universidade Federal de Minas Gerais, Belo Horizonte (Brazil)
• OSTI ID: 6454616
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
BRAZIL
DEFORMATION
DEVELOPING COUNTRIES
GEOLOGIC AGES
GEOLOGIC HISTORY
GEOLOGY
GOLD ORES
HYDROTHERMAL SYNTHESIS
IRON ORES
LATIN AMERICA
METAMORPHIC ROCKS
MINERALIZATION
MINERALOGY
MINERALS
ORES
PETROGENESIS
PETROLOGY
PRECAMBRIAN ERA
ROCKS
SCHISTS
SOUTH AMERICA
SULFIDE MINERALS
SYNTHESIS