Geology and base-metal mineralization associated with archaean iron-formation in the Pojuca Corpo Quatro deposit, Carajás, Brazil
Geology and base-metal mineralization associated with archaean iron-formation in the Pojuca Corpo Quatro deposit, Carajás, Brazil
The Pojuca Corpo Quatro deposit is host to 58Mt of Cu (at a grade of 0.9%) and 8.5Mt of Zn (1%), and is one of several base-metal (±Au) orebodies hosted within Archaean iron-formation on the northwestern edge of the Serra dos Carajá Belt, in the eastern Amazonian Craton of ParáState, Brazil. The near-vertical, SW-dipping strata, within which the Corpo Quatro (C4) deposit is hosted, is known as the Corpo Quatro Formation, and forms part of the regionally extensive IgarapéPojuca Group, dated at 2759 Ma.
A study of the Corpo Quatro Formation, which is composed of a sequence of interbedded volcanic and sedimentary strata, has revealed that the sequence was originally developed as a result of crustal thinning in an intra-continental rifting environment, in which intermittent volcanic activity was accompanied by the deposition of iron-formation and clastic sedimentary rocks. The volcanic activity is characterized by thick units of basaltic- to basaltic andesite affinity, which are comparable with those found in other lithological groups of the Carajá Belt (IgarapéSalobo Group and Gr~ao ParáGroup). Enveloped within the Corpo Quatro basalts, the sedimentary rocks display increased clastic input up sequence, from magnetite-rich iron-formation at the base to quartz-rich pelites at the top. The iron-formation (Rochas Bandadas) at the base of the sedimentary sequence displays mineralogical meso-banding typical of BIF, and grades upwards into silicate (amphibole)-rich iron-formation. This in turn grades into a quartz-rich unit (Rochas Fragmentos), which was formed as a result of mixing of clastic sediments derived from iron-formation and basaltic rock end members. This increase in detrital input is represented by significant enrichment in the relatively immobile elements Al, Ti, Zr, V and Cr, which were introduced via heavy minerals and clays.
University of Southampton
Winter, Caroline Jane
50ef5666-757b-4d4e-8b40-f70b13c07562
1994
Winter, Caroline Jane
50ef5666-757b-4d4e-8b40-f70b13c07562
Winter, Caroline Jane
(1994)
Geology and base-metal mineralization associated with archaean iron-formation in the Pojuca Corpo Quatro deposit, Carajás, Brazil.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The Pojuca Corpo Quatro deposit is host to 58Mt of Cu (at a grade of 0.9%) and 8.5Mt of Zn (1%), and is one of several base-metal (±Au) orebodies hosted within Archaean iron-formation on the northwestern edge of the Serra dos Carajá Belt, in the eastern Amazonian Craton of ParáState, Brazil. The near-vertical, SW-dipping strata, within which the Corpo Quatro (C4) deposit is hosted, is known as the Corpo Quatro Formation, and forms part of the regionally extensive IgarapéPojuca Group, dated at 2759 Ma.
A study of the Corpo Quatro Formation, which is composed of a sequence of interbedded volcanic and sedimentary strata, has revealed that the sequence was originally developed as a result of crustal thinning in an intra-continental rifting environment, in which intermittent volcanic activity was accompanied by the deposition of iron-formation and clastic sedimentary rocks. The volcanic activity is characterized by thick units of basaltic- to basaltic andesite affinity, which are comparable with those found in other lithological groups of the Carajá Belt (IgarapéSalobo Group and Gr~ao ParáGroup). Enveloped within the Corpo Quatro basalts, the sedimentary rocks display increased clastic input up sequence, from magnetite-rich iron-formation at the base to quartz-rich pelites at the top. The iron-formation (Rochas Bandadas) at the base of the sedimentary sequence displays mineralogical meso-banding typical of BIF, and grades upwards into silicate (amphibole)-rich iron-formation. This in turn grades into a quartz-rich unit (Rochas Fragmentos), which was formed as a result of mixing of clastic sediments derived from iron-formation and basaltic rock end members. This increase in detrital input is represented by significant enrichment in the relatively immobile elements Al, Ti, Zr, V and Cr, which were introduced via heavy minerals and clays.
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Published date: 1994
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Local EPrints ID: 462639
URI: http://eprints.soton.ac.uk/id/eprint/462639
PURE UUID: be461e64-64e7-43f7-96b5-9309b971c4e4
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Date deposited: 04 Jul 2022 19:35
Last modified: 16 Mar 2024 18:57
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Author:
Caroline Jane Winter
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