The Pongola Supergroup: Mesoarchaean Deposition Following Kaapvaal Craton Stabilization

Luskin, Casey; Wilson, A. H.; Gold, D.J.C.; Hofmann, Axel

doi:10.1007/978-3-319-78652-0_9

Cited by 20 publications

(20 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The basement of the (eastern) Kaapvaal Craton records voluminous TTG magmatism and formation of greenstone belts from ∼3.7 Ga to 3.2 Ga followed by a pulse of K-granite magmatism at ∼3.1 Ga (50). This was followed by the formation of the Nsuze paleosol and the deposition of the Pongola Supergroup (48), implying that the craton became subaerial by ∼3.1 to 3.0 Ga. This is further corroborated by largescale subaerial volcanism within the craton at ∼2.94 to 2.7 Ga (5).…”

Section: Isostatic Rise Of Magmatically Thickened Crustmentioning

confidence: 83%

“…In addition to the Singhbhum Craton, deposition of Mesoarchean terrestrial to shallow-marine sedimentary strata in the Pilbara, Yilgarn, Slave, Dharwar, and Kaapvaal cratons (16,17) also document the emersion of other cratons by ∼3 Ga. Among them, the ∼2.99to 2.87-Ga Pongola Supergroup of the (eastern) Kaapvaal Craton and the underlying ∼2.99 Ga Nsuze paleosol provide a well-preserved record of subaerial weathering and marginal marine sedimentation atop a stable cratonic basement (47)(48)(49). The basement of the (eastern) Kaapvaal Craton records voluminous TTG magmatism and formation of greenstone belts from ∼3.7 Ga to 3.2 Ga followed by a pulse of K-granite magmatism at ∼3.1 Ga (50).…”

Section: Isostatic Rise Of Magmatically Thickened Crustmentioning

confidence: 86%

“…Additionally, initiation of intense silicate weathering at the craton scale would have promoted a drawn down of atmospheric CO 2 , leading to cooling and icehouse events. These cooling events are likely recorded by the appearance of glacial diamictites in the Mesoarchean, such as those deposited at ∼2.9 Ga in the basins of Pongola Supergroup and West Rand Group of the Kaapvaal Craton (48,50). With the increasing spatial extent of emersed continental landmasses during the Neoarchean, these changes in surficial environments likely became more prominent, permanent, and widespread (1,7).…”

Section: Implications Of Early Continental Emersionmentioning

confidence: 99%

See 2 more Smart Citations

Magmatic thickening of crust in non–plate tectonic settings initiated the subaerial rise of Earth’s first continents 3.3 to 3.2 billion years ago

Chowdhury

Mulder

Cawood

et al. 2021

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

View full text Add to dashboard Cite

When and how Earth's earliest continents—the cratons—first emerged above the oceans (i.e., emersion) remain uncertain. Here, we analyze a craton-wide record of Paleo-to-Mesoarchean granitoid magmatism and terrestrial to shallow-marine sedimentation preserved in the Singhbhum Craton (India) and combine the results with isostatic modeling to examine the timing and mechanism of one of the earliest episodes of large-scale continental emersion on Earth. Detrital zircon U-Pb(-Hf) data constrain the timing of terrestrial to shallow-marine sedimentation on the Singhbhum Craton, which resolves the timing of craton-wide emersion. Time-integrated petrogenetic modeling of the granitoids quantifies the progressive changes in the cratonic crustal thickness and composition and the pressure–temperature conditions of granitoid magmatism, which elucidates the underlying mechanism and tectonic setting of emersion. The results show that the entire Singhbhum Craton became subaerial ∼3.3 to 3.2 billion years ago (Ga) due to progressive crustal maturation and thickening driven by voluminous granitoid magmatism within a plateau-like setting. A similar sedimentary–magmatic evolution also accompanied the early (>3 Ga) emersion of other cratons (e.g., Kaapvaal Craton). Therefore, we propose that the emersion of Earth’s earliest continents began during the late Paleoarchean to early Mesoarchean and was driven by the isostatic rise of their magmatically thickened (∼50 km thick), buoyant, silica-rich crust. The inferred plateau-like tectonic settings suggest that subduction collision–driven compressional orogenesis was not essential in driving continental emersion, at least before the Neoarchean. We further surmise that this early emersion of cratons could be responsible for the transient and localized episodes of atmospheric–oceanic oxygenation (O2-whiffs) and glaciation on Archean Earth.

show abstract

Section: Isostatic Rise Of Magmatically Thickened Crustmentioning

confidence: 83%

Section: Isostatic Rise Of Magmatically Thickened Crustmentioning

confidence: 86%

Section: Implications Of Early Continental Emersionmentioning

confidence: 99%

See 1 more Smart Citation

Magmatic thickening of crust in non–plate tectonic settings initiated the subaerial rise of Earth’s first continents 3.3 to 3.2 billion years ago

Chowdhury

Mulder

Cawood

et al. 2021

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

View full text Add to dashboard Cite

show abstract

“…Subsequently, both, the komatiitic and depleted mantle melts filled magma chambers in the felsic AGC crust and underwent AFC processes that reduced the density of the magmas and the evolved melts could erupt (Figure 12(a)). After this first magmatic event, thermal subsidence led to the deposition of Mozaan Group sediments in a shallow marine environment, likely an epicontinental sea [4,18]. In a second event at around 2860 Ma, magmatism was reactivated and plume-sourced komatiitic parental melts produced the parental magmas of the Mozaan lavas.…”

Section: Mantle Source Compositionmentioning

confidence: 99%

A Mesoarchean Large Igneous Province on the Eastern Kaapvaal Craton (Southern Africa) Confirmed by Metavolcanic Rocks from Kubuta, Eswatini

et al. 2022

View full text Add to dashboard Cite

Mesoarchean magmatism is widespread on the eastern margin of the Kaapvaal Craton, but its origin is still poorly understood, mainly because geochemical data is rare. To shed some light on the source of this Mesoarchean magmatism and to relate different Mesoarchean volcanic sequences to each other, we provide major and trace element data as well as Hf-Nd isotope compositions of amphibolites sampled close to the Kubuta Ranch in south-central Eswatini. These amphibolites, so far, were of unknown correlation to any volcanic sequence in Eswatini or South Africa. Hence, the aim of our study is to characterize the mantle source composition of these volcanic rocks and, furthermore, to constrain their genetic relation to other volcanic sequences in Eswatini and South Africa. Our findings reveal that, based on coherent trace element patterns and similar Nd isotope characteristics, the Kubuta volcanic rocks can be genetically linked to the ca. 3.0 Ga Usushwana Igneous Complex in West-Central Eswatini and the ca. 2.9 Ga Hlagothi Complex located in the KwaZulu-Natal province. In contrast, the coeval ca. 3.0 Ga Nsuze and ca. 2.9 Ga Mozaan Groups (Pongola Supergroup) of south-central Eswatini and northern KwaZulu-Natal province have slightly enriched compositions compared to the newly sampled Kubuta volcanic rocks. Our results suggest that the Nsuze and Mozaan Groups were sourced from a primitive mantle reservoir, whereas the Usushwana, Hlagothi, and Kubuta mafic rocks were derived by melting of a more depleted mantle source comparable to that of modern depleted MORB. Furthermore, our assimilation-fractional crystallization (AFC) calculations and Nd isotope constraints reveal that some samples were contaminated by the crust and that the crustal contaminants possibly represent felsic rocks related to the ca. 3.5 Ga crust-forming event in the Ancient Gneiss Complex. Alternatively, melting of a metasomatized mantle or plume-lithospheric mantle interaction may also produce the trace element and isotopic compositions observed in the samples. From a synthesis of our geochemical observations and age data from the literature, we propose a refined petrogenetic model, for a continental flood basalt setting in a Mesoarchean large igneous province on the eastern Kaapvaal Craton. Our petrogenetic model envisages two magma pulses sourced from a primitive mantle reservoir that led to the formation of the Nsuze (first) and Mozaan (second) lavas. Conductive heating of ambient depleted mantle by the mantle plumes caused partial melting that led to the formation of the Usushwana Igneous Complex associated with the first magmatic event (Nsuze) and the Hlagothi Igneous Complex associated with the second magmatic event (Mozaan). However, due to lacking age data of sufficient resolution, it is not possible to affiliate the Kubuta lavas to either the first or the second magmatic event.

show abstract

“…In the north of the study area (Figure B), the basement is formed by the south‐eastern margin of the Kaapvaal Craton, which consists of an assemblage of Archaean lithologies. The ~2.9 Ga Pongola Supergroup, which forms the dominant substrate for the Dwyka Group, is made up of tilted and folded sedimentary and volcanic rocks metamorphosed at greenschist facies grade (Luskin et al , ). Locally, in the central part of the study area, fragments of 3.3–3.4 Ga greenstone belts are exposed.…”

Section: Geological Settingmentioning

confidence: 99%

Ice‐margin fluctuation sequences and grounding zone wedges: The record of the Late Palaeozoic Ice Age in the eastern Karoo Basin (Dwyka Group, South Africa)

Dietrich

Hofmann

2019

The Depositional Record

Self Cite

View full text Add to dashboard Cite

In the eastern part of the Karoo Basin of South Africa, the sedimentary record of the Late Palaeozoic Ice Age, the Dwyka Group, consists of an up to 200 m thick accumulation of massive to crudely stratified diamictite occasionally interstratified with siltstone, sandstone and conglomerate horizons. Three distinct sedimentary units, separated by intervening glacial erosion surfaces, are viewed as ice‐margin fluctuation sequences. The lowermost one, resting on highly uneven, glacially abraded Archaean basement, has been interpreted as a grounding zone wedge deposited after the retreat and stabilization of the ice margin after the inundation of the Karoo Basin. The grounding zone wedge interpretation is based on its thickness (up to 100 m), the dominance of diamictite, and its facies assemblage and inferred depositional processes (rain‐out of debris, dropstone dumping, mass and debris flow, till). Overlying the grounding zone wedge, deposits are sedimentary units interpreted as glaciofluvial or ice‐contact delta and grounding zone wedges, respectively. By analogy with Quaternary sedimentary sequences, deposition of the Dwyka Group in the study area might have been very rapid (tens to hundreds of thousand years) and may hence correlate with the ultimate deglacial sequence of the Western Karoo Basin, as both successions are covered by the postglacial Ecca Group. Although commonly observed and imaged on modern, high‐latitude continental shelves, grounding zone wedges have never been interpreted in the ancient geological record. This paper therefore outlines a model defining criteria necessary for their identification.

show abstract

The Pongola Supergroup: Mesoarchaean Deposition Following Kaapvaal Craton Stabilization

Cited by 20 publications

References 58 publications

Magmatic thickening of crust in non–plate tectonic settings initiated the subaerial rise of Earth’s first continents 3.3 to 3.2 billion years ago

Magmatic thickening of crust in non–plate tectonic settings initiated the subaerial rise of Earth’s first continents 3.3 to 3.2 billion years ago

A Mesoarchean Large Igneous Province on the Eastern Kaapvaal Craton (Southern Africa) Confirmed by Metavolcanic Rocks from Kubuta, Eswatini

Ice‐margin fluctuation sequences and grounding zone wedges: The record of the Late Palaeozoic Ice Age in the eastern Karoo Basin (Dwyka Group, South Africa)

Contact Info

Product

Resources

About