Ore Geology Reviews

Autor: Misi, Aroldo, Iyer, Sundaram Sankara Subba, Coelho, Carlos Eduardo Silva, Tassinari, Colombo Celso Gaeta, Rocha, Washington J. S. Franca, Cunha, Ioná de Abreu, Gomes, Adriana S. Rocha, Oliveira, Tolentino Flávio de, Teixeira, João Batista Guimarães, Conceição Filho, Valter Mônaco
Jazyk: angličtina
Rok vydání: 2005
Předmět:
Zdroj: Repositório Institucional da UFBA
Universidade Federal da Bahia (UFBA)
instacron:UFBA
ISSN: 0169-1368
Popis: p. 263–304 Submitted by Ana Valéria de Jesus Moura (anavaleria_131@hotmail.com) on 2012-01-26T15:59:26Z No. of bitstreams: 1 S016913680500020X-main.pdf: 2085935 bytes, checksum: ca02adfba2f94589150a37f9ca97e874 (MD5) Made available in DSpace on 2012-01-26T15:59:26Z (GMT). No. of bitstreams: 1 S016913680500020X-main.pdf: 2085935 bytes, checksum: ca02adfba2f94589150a37f9ca97e874 (MD5) Previous issue date: 2005 The Proterozoic sediment-hosted Zn–(Pb) sulfide and non-sulfide deposits of the São Francisco Craton, Brazil, are partially syn-diagenetic and epigenetic and were probably formed during extensional events. The majority of the deposits occur within shallow water dolomites. The Pb isotopic data of sulfides are relatively homogeneous for individual deposits and plot above the upper crust evolution curve of the Plumbotectonic model. Some of the deposits are characterized by highly radiogenic lead (206Pb/204Pb ≥ 21) originating from the highly radioactive crust of the São Francisco Craton. Pb and S isotopic data suggest the sources of metal and sulfur for the deposits to be the basement rocks and seawater sulfates in the sediments, respectively. The relatively high temperatures of formation (100 to 250 °C) and moderate salinity (3% to 20% NaCl equiv.) of the primary fluid inclusions in the sphalerite crystals suggest the participation of basinal mineralizing fluids in ore formation. The steep paleo-geothermal gradient generated by the radioactively enriched basement rocks probably assisted in heating up the circulating mineralizing fluids.
Databáze: OpenAIRE
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