Juvenile crust formation in the Zimbabwe Craton deduced from the O-Hf isotopic record of 3.8–3.1 Ga detrital zircons

Bolhar, Robert; Hofmann, Axel; Kemp, Anthony I.S.; Whitehouse, Martin J.; Wind, Sandra; Kamber, Balz S.

doi:10.1016/j.gca.2017.07.008

Cited by 40 publications

(8 citation statements)

References 78 publications

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“…While the Limpopo belt does not clearly document a similar trend, detrital zircons from the Zimbabwe Craton do ( Fig. S-11; Bolhar et al, 2017). et al, 2017), our interpretations are not inconsistent with a separate tectonic change at ~3.0 Ga.…”

Section: The Global Hf Isotope Datasetcontrasting

confidence: 50%

Hafnium isotopes in zircons document the gradual onset of mobile-lid tectonics

Bauer¹,

Reimink²,

Chacko³

et al. 2020

Geochem. Persp. Let.

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The tectonic regime of the early Earth has proven enigmatic due to a scarcity of preserved continental crust, yet how early continents were generated is key to deciphering Earth's evolution. Here we show that a compilation of data from 4.3 to 3.4 Ga igneous and detrital zircons records a secular shift to higher 176 Hf/ 177 Hf after ~3.8-3.6 Ga. This globally evident shift indicates that continental crust formation before ~3.8-3.6 Ga largely occurred by internal reworking of long-lived mafic protocrust, whereas later continental crust formation involved extensive input of relatively juvenile magmas, which were produced from rapid remelting of oceanic lithosphere. We propose that this secular shift in the global hafnium isotope record reflects a gradual yet widespread transition from stagnant-lid to mobile-lid tectonics on the early Earth.

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Section: The Global Hf Isotope Datasetcontrasting

confidence: 50%

Hafnium isotopes in zircons document the gradual onset of mobile-lid tectonics

Bauer¹,

Reimink²,

Chacko³

et al. 2020

Geochem. Persp. Let.

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“…However, detrital zircon grains preserved in the quartzites from the greenstone belts in Zimbabwe have yielded ages up to ca. 3.8 Ga (Dodson et al ., 1988; Bolhar et al ., 2017). The Zimbabwe Craton is mainly confined to Zimbabwe, with an extension into the northeastern part of Botswana, where it is represented by the Francistown Arc Complex (Carney et al ., 1994; McCourt et al ., 2004).…”

Section: Geological Frameworkmentioning

confidence: 99%

Geology, mineralogy, and sulfur isotopes of the Mowana copper deposit, Matsitama Schist Belt, NE Botswana

et al. 2021

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The Mowana hydrothermal Cu deposit is located within the Matsitama–Motloutse Complex in the southwestern part of the Zimbabwe Craton in the northeastern part of Botswana. This study aims to document the characteristics of the mineralization based on geology, quartz textures, ore mineralogy, chlorite geothermometry, and sulfur isotope analyses. The deposit is hosted by the NNE‐striking and nearly vertically dipping (70–80°) Bushman Lineament, within the graphitic schist lenses in the carbonaceous and argillaceous metasedimentary rocks of the Neoarchean to Paleoproterozoic Matsitama Sedimentary Group. The hydrothermal alteration of the host rocks is characterized by silicification, chloritization, epidotization, sericitization, hematite, and calcite alteration. Based on the alteration mineral assemblage, the main mineralization stage is attributed to near neutral pH fluids at temperatures between ~200 and ~340°C. The base metal mineralization of the Mowana deposit was evolved in at least two vein types. The first mineralization type, represented by the quartz+calcite±K‐feldspar veins and breccias is characterized by the precipitation of principal chalcopyrite with pyrite, minor bornite, and trace amounts of galena. The Type 2 veins represented by the quartz+calcite±fluorite veins, host appreciable amounts of galena. The supergene mineralization widely distributed in the shallow levels of the deposit is manifested by the significant presence of chalcocite, bornite, covellite, anglesite, malachite, and hematite. The temperature obtained from the chlorite geothermometry in the Type 1 veins indicate that the mineralization associated with chlorite alteration formed at a temperature ranging from 340 to 400°C. The ore mineral assemblage: pyrite, bornite, and chalcopyrite, paired with the chlorite geothermometry data indicate that the Type 1 veins formed at an intemediate to high sulfidation state. Sulfur isotopic ratios determined on the sulfides indicate the magmatic S and/or leaching of the host metasedimentary rocks and closed system reduction of seawater sulfate as the sources of S.

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“…3.0 Ga Naharmagra quartzite of the North Delhi belt in the Aravalli Craton (Raza et al, 2010), and ca. 3.3 Ga Sebakwian quartzite on the Zimbabwe Craton (Bolhar et al, 2017). Older Archean siliceous sandstones also exist, for example, the ca.…”

Section: Quartzose Sandstone and The Size Of Continents In The Archean Crustmentioning

confidence: 99%

“…The ca. 3.3-2.5 Ga quartzose sandstone and quartzite in the continental rift basin or passive margin show complex detrital zircon age patterns and often contain Eoarhcean and Hadean ones (e.g., Sircombe et al, 2001;Maier et al, 2012;Zeh et al, 2014;Bolhar et al, 2017), indicating that their detrital grains are widely provided from relatively large areas. Furthermore, it is noteworthy that Hadean detrital zircon grains occur in ca.…”

Section: Quartzose Sandstone and The Size Of Continents In The Archean Crustmentioning

confidence: 99%

Estimation of Secular Change in the Size of Continents for Understanding Early Crustal Development

Sawada

2020

Front. Earth Sci.

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The size of continents is an essential parameter to understand the growth of the continental crust and the evolution of the solid Earth because it is subject to tectonism and mantle convection and affects the preservation of the crust. This article reviews the secular change in the size of continents on the early Earth, focusing on terrigenous clastic rocks, especially quartzose sandstones occurring on relatively large continents. The earliest continental crust in the Hadean or early Archean was produced with a width of ∼200–500 km, similar to modern oceanic island arcs along subduction zones or oceanic islands in hot spot regions by mantle plume heating. Through the collision and amalgamation of such primitive continental crusts, continental blocks over 500 km in width and length evolved and appeared by ca. 3.5 Ga. Through further amalgamation, during ca. 3.3–2.5 Ga, the Archean continents emerged with widths and lengths greater than 1,000 km, which were still smaller than those of modern continents. Continents with widths and lengths of nearly 10,000 km have existed since ca. 2.4 Ga (early Proterozoic). Further analyses of the composition and formation mechanism of clastic rocks will help reveal more quantitative secular changes in the sizes of continents.

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Juvenile crust formation in the Zimbabwe Craton deduced from the O-Hf isotopic record of 3.8–3.1 Ga detrital zircons

Cited by 40 publications

References 78 publications

Hafnium isotopes in zircons document the gradual onset of mobile-lid tectonics

Hafnium isotopes in zircons document the gradual onset of mobile-lid tectonics

Geology, mineralogy, and sulfur isotopes of the Mowana copper deposit, Matsitama Schist Belt, NE Botswana

Estimation of Secular Change in the Size of Continents for Understanding Early Crustal Development

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