Evolving mantle convection from bottom up to top down

Mitchell, Ross N.; Brown, Michael; Gernon, Thomas; Spencer, Christopher J.

doi:10.1016/j.xinn.2022.100309

Cited by 2 publications

(4 citation statements)

References 3 publications

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“…However, the exponential decay signature is not observed in our predictions (Figure 2b). In addition, the increase of kimberlite occurrences has been proposed to be concomitant with the respective rise and fall of Archean komatiite and Proterozoic anorthosite frequency (Mitchell et al., 2022; Tappe et al., 2018). It is noted that zircon saturation in melts generally increases with the decreased SiO 2 content (Shao et al., 2020), indicating low abundances of zircon records for the natural silica‐undersaturated carbonatites, kimberlites, and mafic rocks.…”

Section: Discussionmentioning

confidence: 99%

“…On the other hand, the increasing amounts of carbonatite‐alkaline melts are generally coupled with secular mantle cooling, which increases the operation of incipient melting relative to major melting (Tappe et al., 2018). Mantle cooling also favors the transport and sequestration of carbon into the deep mantle through cold subduction zones (Dasgupta, 2013; Mitchell et al., 2022). The prediction of prominent continental alkaline magmas postdating ∼1,300 Ma may confirm a previous conjectural projection that the geothermal gradient and slab steepness in subduction zones were not amenable to allow significant subduction of crustal carbonates until the mid to late Proterozoic Eon (Dasgupta, 2013; Mitchell et al., 2022).…”

Section: Discussionmentioning

confidence: 99%

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The Role of Continental Alkaline Magmatism in Mantle Carbon Outflux Constrained by a Machine Learning Analysis of Zircon

Wang,

Liu,

Spencer

et al. 2024

Geophysical Research Letters

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Continental alkaline magmatism has been suggested to play a significant role in releasing deep mantle carbon into the atmosphere, which can greatly impact the global climate. However, the temporal variations of alkaline magmatism and their potential to modulate climate over geologic time remain poorly constrained. The detrital zircon record is a frequently used proxy for tracking secular variations in particular magmatism. Here, we use a novel machine‐learning technique to discriminate zircon from carbonatites, kimberlites, and other alkaline rocks. A global compilation of detrital zircon yields continental alkaline magmatic flare‐ups between 1,050−850, 650−500, 250−200, and 50−0 Ma. Our estimates indicate relatively elevated contributions of total magmatic carbon outgassing from alkaline magmatism during the aforementioned magmatic flare‐ups. We infer that anomalous alkaline magmatism may influence global warming during specific intervals of geologic time, but when they are not that voluminous or persistent extensive arc magmatism may drive warming conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The Role of Continental Alkaline Magmatism in Mantle Carbon Outflux Constrained by a Machine Learning Analysis of Zircon

Wang,

Liu,

Spencer

et al. 2024

Geophysical Research Letters

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“…The sudden outburst of biogenic carbonate platforms globally around 2.5 Ga (Fig. 10) may thus share a common triggering mechanism, showing a link of deep Earth processes such as a transition from bottom-up to top-down mantle convection 69 and the oxygenation of the atmosphere near the Archaean-Proterozoic boundary 3,[66][67][68] . As protocontinents were generally stabilized by intraoceanic arc amalgamation around the Archaean-Proterozoic boundary 2 , biogenic carbonate platforms were built as a consequence.…”

Section: Discussionmentioning

confidence: 99%

“…As protocontinents were generally stabilized by intraoceanic arc amalgamation around the Archaean-Proterozoic boundary 2 , biogenic carbonate platforms were built as a consequence. The sudden rise of oxygen from these oases eventually led to global change and the later GOE event started about 2.45 Gyr, making Earth a more habitable planet [66][67][68][69] .…”

Section: Discussionmentioning

confidence: 99%

Passive margins in accreting Archaean archipelagos signal continental stability promoting early atmospheric oxygen rise

et al. 2022

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Significant changes in tectonic style and climate occurred from the late Archaean to early Proterozoic when continental growth and emergence provided opportunities for photosynthetic life to proliferate by the initiation of the Great Oxidation Event (GOE). In this study, we report a Neoarchaean passive-margin-type sequence (2560–2500 million years ago) from the Precambrian basement of China that formed in an accretionary orogen. Tectonostratigraphic and detrital zircon analysis reveal that thermal subsidence on the backside of a recently amalgamated oceanic archipelago created a quiet, shallow water environment, marked by deposition of carbonates, shales, and shallow water sediments, likely hosts to early photosynthetic microbes. Distinct from the traditional understanding of passive margins generated by continental rifting, post-collisional subsidence of archipelago margins represents a novel stable niche, signalling initial continental maturity and foreshadowing great changes at the Archaean-Proterozoic boundary.

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Evolving mantle convection from bottom up to top down

Cited by 2 publications

References 3 publications

The Role of Continental Alkaline Magmatism in Mantle Carbon Outflux Constrained by a Machine Learning Analysis of Zircon

The Role of Continental Alkaline Magmatism in Mantle Carbon Outflux Constrained by a Machine Learning Analysis of Zircon

Passive margins in accreting Archaean archipelagos signal continental stability promoting early atmospheric oxygen rise

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