Distribution and geochemical characteristics of barite and barium-rich rocks associated with the Broken Hill-type Gamsberg Zn-Pb deposit, Namaqua Province, South Africa

Stalder, Marcel

doi:10.2113/108.1.35

Cited by 15 publications

(6 citation statements)

References 28 publications

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“…Stratigraphic column of the meta‐volcanosedimentary sequence at Aggeneys (after Colliston et al., 2012; Cornell et al., 2006; Stalder & Rozendaal, 2005) [Colour figure can be viewed at wileyonlinelibrary.com]…”

Section: Geological Settingmentioning

confidence: 99%

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

et al. 2020

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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.

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Section: Geological Settingmentioning

confidence: 99%

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

et al. 2020

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“…These deposits are typically hosted in intensely deformed gneisses and mafic to ultramafic supracrustal rocks, folded into nappes and isoclinal recumbent folds, subsequently refolded into late open synforms and antiforms (e.g. Ryan et al, 1986;Naicker, 1993;Reid et al, 1997;Colliston and Schoch, 2002;Bailie and Reid, 2005;Stalder and Rozendaal, 2005;Bailie et al, 2007) or, in plug-and sheet-like bodies e.g. the Koperberg Suite gneisses of the Okiep Copper District (e.g.…”

Section: Kango and Kaaimans Tectonic Inliers Generally Linked To The mentioning

confidence: 99%

Deep Crustal Profile Across the Southern Karoo Basin and Beattie Magnetic Anomaly, South Africa: An Integrated Interpretation With Tectonic Implications

Lindeque

Wit

Ryberg

et al. 2011

South African Journal of Geology

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Two geophysical onshore-offshore lines on the southern margin of Africa form the Agulhas-Karoo Geophysical Transect (AKGT) and cross prominent geological features such as the Karoo Basin, Cape Fold Belt (CFB) and the Beattie Magnetic Anomaly (BMA). Geophysical data acquired along this AKGTransect between 2004 and 2007 within the Inkaba yeAfrica (lyA) framework, provide the platform for constructing a deep crustal section (IyA-200501) for the centre 100 km of the western AKGT-transect in order to resolve these features at depth. We present a detailed deep crustal model constructed from the joint interpretation of: i. archive data comprising surface geology, aeromagnetic data, nearby deep boreholes, teleseismic receiver functions and regional seismic reflection profiles, and ii. line coincident newly acquired high-resolution geophysical data consisting of near vertical seismic reflection data, shallow P-and S-wave velocity data, wide-angle refraction data, high resolution magnetotelluric data and impedance spectroscopy measurements on borehole samples. Our model differentiates four components in the up to 45 km thick crust: 1. a ~2 to 5 km thick folded Karoo Supergroup, disrupted by low-angle thrust faults rooted in a zone of local décollements in the lower Ecca Group and resting paraconformably on 2. a continuous undeformed sub-horizontal ~1.5 to 10 km thick wedge of the Cape Supergroup (CSG). This CSG wedge stretches from the Escarpment in the north to the tectonic front of the CFB in the south, and rests on an unconformity that dips about three degrees to the south. The angular unconformity is interpreted as an erosional peneplain that separates the CSG wedge from component 3. the ~13 to 21 km mid-crust basement below. The mid-crust contains a distinct north-dipping seismic fabric, here interpreted as 1.4 to 1.0 Ga Mesoproterozoic Namaqua-Natal Metamorphic Belt (NNMB) crust. A south-dipping mid-crustal detachment, interpreted as a ductile thrust zone, separates the mid-crust from component 4. a highly reflective ~10 to 24 km thick lower crust. The latter is interpreted as an older Palaeoproterozoic section of the NNMB (or even Archean cratonic basement), and bounded by a ~2 to 5 km thick, highly reflective bottom layer below that lies subparallel to a clear Moho. This bottom layer is interpreted as a mafic underplate, metasomatic reaction zone, or lower-crust to mantle transition zone. Collectively the seismic reflection and wide-angle refraction data support an interpretation that the NNMB mid-crustal layer contains the BMA source, possibly connected to two zones of strong reflectivity: a ~10 to 12 km wide northern zone and a ~5 to 7 km wide southern zone, both about 5 km thick and 7 to 8 km below surface. We interpret the BMA source to be at least in part, a Namaqua-like massive to disseminated, deformed/metamorphosed stratiform sulphide-magnetite ore body with metasomatic overprint.

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“…The deposition of this volcano-sedimentary sequence with a thickness of <1500 m (Stalder and Rozendaal, 2005) occurred between 1.64 and ~1.2 Ga (Bailie and Reid, 2005). The youngest age marks the onset of the Kibaran orogeny 1.21 Ga (Bailie et al, 2007;Cornell et al, 2009).…”

Section: Regional Geological Settingmentioning

confidence: 97%

“…Aggeneys has been chosen as a test site because the outcropping (Figure 1) litho-stratigraphic units are large enough to be relevant on the spaceborne scale of ~30 m per pixel (Stalder and Rozendaal, 2005). In addition, the vegetation is sparse and subdued and has only a minor impact on the Introduction Big Syncline and Gamsberg area were collected by the Hyperion sensor.…”

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confidence: 99%

Multi- and hyperspectral spaceborne remote sensing of the Aggeneys base metal sulphide mineral deposit sites in the Lower Orange River region, South Africa

Mielke

Muedi

Papenfuß

et al. 2016

South African Journal of Geology

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New tools and algorithms for geological remote sensing are developed and verified at test sites throughout the world in preparation of the German hyperspectral satellite Mission (EnMAP), which is an Environmental Mapping and Analysis Program.The Aggeneys Cu-Pb-Zn deposit, situated in the arid north western part of South Africa, represents a unique field laboratory for testing these new tools. Here spaceborne hyperspectral data covering the Swartberg, SOUTH

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Distribution and geochemical characteristics of barite and barium-rich rocks associated with the Broken Hill-type Gamsberg Zn-Pb deposit, Namaqua Province, South Africa

Cited by 15 publications

References 28 publications

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

Pre‐Klondikean oxidation prepared the ground for Broken Hill‐type mineralization in South Africa

Deep Crustal Profile Across the Southern Karoo Basin and Beattie Magnetic Anomaly, South Africa: An Integrated Interpretation With Tectonic Implications

Multi- and hyperspectral spaceborne remote sensing of the Aggeneys base metal sulphide mineral deposit sites in the Lower Orange River region, South Africa

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