The major early Proterozoic sedimentary iron and manganese deposits and their tectonic setting

Schissel, Don; Aro, Phil

doi:10.2113/gsecongeo.87.5.1367

Cited by 30 publications

(20 citation statements)

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“…In modern eutrophic lakes, manganese oxidation is vastly accelerated by bacteria, and the deposition of aqueous manganese is directly coupled with the release of O 2 from cyanobacterial blooms (41), conditions that are similar to those inferred for the deposition of BIFs (42,43). These postsnowball oceanic conditions closely match models for the deposition of both early and late Proterozoic sedimentary manganese formations (24,25,27). The Fe and Mn that accumulated in the global ocean would have been sufficient to form deposits like the basal 50 m of the Hotazel formation over an area of 10 6 -10 The lack of organic material in BIFs has been used to argue against biological mechanisms of oxidation (42).…”

supporting

confidence: 67%

“…2)], making the Kalahari manganese field by far the world's largest land-based economic reserve of this element (21)(22)(23). Major deposits of Mn associated with BIFs occur only twice in the geological record, and both follow directly after inferred snowball Earth events in the Paleoproterozoic and Neoproterozoic (24)(25)(26)(27) Manganese has a high oxidation potential (E 0 ϭ Ϫ1.29 V with respect to the hydrogen standard), and the Kalahari manganese field seems to represent a transition in the oxidation state of Earth's surface, which is in rough temporal agreement (J.G. and N.J.B., unpublished work; ref.…”

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confidence: 90%

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Paleoproterozoic snowball Earth: Extreme climatic and geochemical global change and its biological consequences

Kirschvink

Gaidos

Bertani

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

393

211

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supporting

confidence: 67%

mentioning

confidence: 90%

Paleoproterozoic snowball Earth: Extreme climatic and geochemical global change and its biological consequences

Kirschvink

Gaidos

Bertani

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

393

211

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“…Oxidation of aqueous Mn(II) to Mn(III/IV) solids is required to concentrate Mn in iron formation (14). Major Paleoproterozoic Mn deposits, including the ∼2.22 Ga Kalahari Manganese Field in South Africa, developed in response to the rise in environmental O 2 (41,42). Here we report the study of a sedimentary succession underlying and substantially older than the Kalahari deposit but also bearing strong authigenic Mn enrichments.…”

mentioning

confidence: 91%

Manganese-oxidizing photosynthesis before the rise of cyanobacteria

Johnson

Webb

Thomas

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

207

137

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The emergence of oxygen-producing (oxygenic) photosynthesis fundamentally transformed our planet; however, the processes that led to the evolution of biological water splitting have remained largely unknown. To illuminate this history, we examined the behavior of the ancient Mn cycle using newly obtained scientific drill cores through an early Paleoproterozoic succession (2.415 Ga) preserved in South Africa. These strata contain substantial Mn enrichments (up to ∼17 wt %) well before those associated with the rise of oxygen such as the ∼2.2 Ga Kalahari Mn deposit. Using microscale X-ray spectroscopic techniques coupled to optical and electron microscopy and carbon isotope ratios, we demonstrate that the Mn is hosted exclusively in carbonate mineral phases derived from reduction of Mn oxides during diagenesis of primary sediments. Additional observations of independent proxies for O 2 -multiple S isotopes (measured by isotope-ratio mass spectrometry and secondary ion mass spectrometry) and redoxsensitive detrital grains-reveal that the original Mn-oxide phases were not produced by reactions with O 2 , which points to a different high-potential oxidant. These results show that the oxidative branch of the Mn cycle predates the rise of oxygen, and provide strong support for the hypothesis that the water-oxidizing complex of photosystem II evolved from a former transitional photosystem capable of single-electron oxidation reactions of Mn.water oxidation | X-ray absorption spectroscopy | Great Oxidation Event | pyrite

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“…Because these models were not challenged, the Kalahari Manganese Field became entrenched in the literature as an example of a sedimentary manganese deposit (e.g. Roy, 1992;Schissel and Aro, 1992).…”

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confidence: 99%

A volcanic-exhalative origin for the world's largest (Kalahari) Manganese field

Cornell¹,

Schütte

1995

Mineral. Deposita

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In a recent paper Cornell and Schiitte (1995) suggest that the Kalahari manganese field (KMF) is of volcanogenic-exhalative origin with the manganese directly derived from the underlying Ongeluk lavas. They state in their final paragraph that this new model is to supersede the existing sedimentary models for the deposit proposed for example by Beukes (1983). However, the model proposed by Cornell and Schfitte (1995) is unacceptable because it does not take into account any of the established fundamental geological features such as stratigraphy, sedimentology, petrography, mineral paragenesis, regional geology, structural geology, and hydrothermal alteration of the manganese ores. The model of Cotnell and Schiitte (1995) is based purely on chemical analyses of samples for which the geological setting is not indicated at all. It is also based on some misconceptions regarding the geology and mineralogy of the manganese ores of the KMF in particular, and manganese deposition in general. They also provide no objective geological evidence to prove that their so-called 'Kalahari alteration" of the Ongeluk lava is syngenetic with the formation of the overlying iron-formations and manganese ores. In fact, they totally disregard the presence of iron-formations which are interbedded with the manganese ore beds.

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The major early Proterozoic sedimentary iron and manganese deposits and their tectonic setting

Cited by 30 publications

References 0 publications

Paleoproterozoic snowball Earth: Extreme climatic and geochemical global change and its biological consequences

Paleoproterozoic snowball Earth: Extreme climatic and geochemical global change and its biological consequences

Manganese-oxidizing photosynthesis before the rise of cyanobacteria

A volcanic-exhalative origin for the world's largest (Kalahari) Manganese field

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