TY  - JOUR
A1  - Höhn, Stefan
A1  - Frimmel, Hartwig E.
A1  - Debaille, Vinciane
A1  - Price, Westley
T1  - Pre-Klondikean oxidation prepared the ground for Broken Hill-type mineralization in South Africa
Y1  - 2020
JF  - Terra Nova
DO  - 10.1111/ter.12502
DO  - 10.23689/fidgeo-4441
N2  - New Cu isotope data obtained on chalcopyrite from the Black Mountain and the Broken Hill deposits in the medium- to high-grade metamorphic Aggeneys-Gamsberg ore district (South Africa) require a revision of our understanding of the genesis of metamorphic Broken Hill-type massive sulphide deposits. Chalcopyrite from both deposits revealed unusually wide ranges in δ65Cu (−2.41 to 2.84‰ NIST 976 standard) in combination with distinctly positive mean values (0.27 and 0.94‰, respectively). This is interpreted to reflect derivation from various silicate and oxide precursor minerals in which Cu occurred in higher oxidation states. Together with the observation of a typical supergene base metal distribution within the deposits and their spatial association with an unconformity only meters above the ore horizon, our new data are best explained by supergene oxidation of originally possibly SEDEX deposits prior to metamorphic sulphide formation, between the Okiepian (1,210–1,180 Ma) and Klondikean (1,040–1,020 Ma) orogenic events.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/8787
ER  -