Polyphase Metallogenesis in the Carajás Cu-Au Belt, Brazil


ABSTRACT: Polyphase Cu-Au metallogenesis in the Carajás Cu- Au Belt, Brazil is considered to have occurred in three distinct epochs, ca. 2.76, ca. 2.55 Ga and a ca. 1.88 Ga. The 2.76 Ga event coincides with formation of the Itacaiúnas Supergroup host rocks and emplacement of the Estrela granite complex. An intrusion-related genesis for 2.55 Ga IOCG mineralization has been accepted at the Salobo deposit, however, contradictory data and models persist for the Igarapé Bahia- Alemão, Serra Pelada, Cento e Dezoito and Igarapé Cinzento deposits. Ore genesis models and age determinations at the Serra Verde and Igarapé Bahia-Alemão deposits may be consistent with a primary syngenetic model. REE mineral age dating has been interpreted to indicate a ca. 1.88 Ga intrusion-related Cu (IR-Cu) class, at the Breves deposit, however contradictory age dating and/ or ore genesis interpretations exist for the Estrela, Águas Claras and Gameleira deposits. Ore genesis models for IR-Cu deposits, are indeed complex as these Cu-dominant systems are associated with variable amounts of Au, Ag, W, Mo, Sn, Bi, enrichments in As, Ni, Co, Zn and Pb, and the common association of B, F and or Li in their gangue mineralogy.

KEYWORDS: Carajás, IOCG deposit, intrusion-related Cu, geochronology

EAN: SGA_2007_A010
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