Ultra-high pressure inclusion in Archean ophiolitic podiform chromitite in mélange block suggests deep subduction on early Earth

Kusky, Timothy M.; Wang, Lu; Robinson, Paul T.; Huang, Yang H.; Wirth, Richard; Ning, Wenbin; Zhong, Yating; Polat, Ali

doi:10.1016/j.precamres.2021.106318

Cited by 22 publications

(8 citation statements)

References 81 publications

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“…Alternatively, this diamond may have formed during oceanic lithospheric slab subducted to depths where rocks experienced eclogite facies conditions and microdiamonds crystallized from C-rich fluids produced by metamorphic dehydration of slabs. This process is consistent with the formation of UHP minerals hosted in an ophiolitic podiform chromitite mélange from the Neoarchean metamorphic belt of the Central (Taihang) Orogenic Belt, Northern China [156]. We name this kind of microdiamond oceanic lithospheric subduction-type diamond to distinguish it from diamonds categorized as the mantle transition zone-type discovered in fresh ophiolitic mantle peridotite and chromitite.…”

Section: Controversy and Future Perspectivessupporting

confidence: 74%

Diamond and Other Exotic Mineral-Bearing Ophiolites on the Globe: A Key to Understand the Discovery of New Minerals and Formation of Ophiolitic Podiform Chromitite

Liu

Lian

et al. 2021

Crystals

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Ophiolite-hosted diamond from peridotites and podiform chromitites significantly differs from those of kimberlitic diamond and ultra-high pressure (UHP) metamorphic diamond in terms of occurrence, mineral inclusion, as well as carbon and nitrogen isotopic composition. In this review, we briefly summarize the global distribution of twenty-five diamond-bearing ophiolites in different suture zones and outline the bulk-rock compositions, mineral and particular Re-Os isotopic systematics of these ophiolitic chromitites and host peridotites. These data indicate that the subcontinental lithospheric mantle is likely involved in the formation of podiform chromitite. We also provide an overview of the UHP textures and unusual mineral assemblages, including diamonds, other UHP minerals (e.g., moissanite, coesite) and crustal minerals, which robustly offer evidence of crustal recycling in the deep mantle along the suprasubduction zone (SSZ) and then being transported to shallow mantle depths by asthenospheric mantle upwelling in mid-ocean-ridge and SSZ settings. A systematic comparison between four main genetic models provides insights into our understanding of the origin of ophiolite-hosted diamond and the formation of podiform chromitite. Diamond-bearing peridotites and chromitites in ophiolites are important objects to discover new minerals from the deep earth and provide clues on the chemical composition and the physical condition of the deep mantle.

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Section: Controversy and Future Perspectivessupporting

confidence: 74%

Diamond and Other Exotic Mineral-Bearing Ophiolites on the Globe: A Key to Understand the Discovery of New Minerals and Formation of Ophiolitic Podiform Chromitite

Liu

Lian

et al. 2021

Crystals

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“…S1 A ). Preserved structural and lithic records of this collision include a series of Archean ophiolitic (oceanic crust and mantle) fragments and tectonic mixtures of rocks known as mélanges ( 19 ), exotic belts of forearc magmatic rocks that preserve Archean subduction initiation sequences ( 20 ), paired metamorphic belts ( 21 ), ultrahigh-pressure (UHP) metamorphic crustal minerals ( 22 ), forearc and accretionary complexes ( 23 ), and Alpine-style subhorizontal arc–affinity nappes emplaced over a continental margin ( 24 ), all of which are diagnostic indicators of asymmetric Archean subduction and large plate translations and analogous to modern subduction at convergent tectonic margins. Nevertheless, the deep subduction of Archean oceanic crust demarked by hallmark vestiges of orogenic eclogites has not been documented in the NCC or anywhere worldwide.…”

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confidence: 99%

Archean eclogite-facies oceanic crust indicates modern-style plate tectonics

Ning

Kusky

Wang

et al. 2022

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

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Significance The onset time of plate tectonics is highly debated in the Earth sciences. A key indicator of modern-style plate tectonics, with deep subduction of oceanic plates, is the presence of eclogite (oceanic crust metamorphosed at high-pressure and low-temperature) in orogenic belts. Since no orogenic eclogites older than 2.1 billion y are currently documented, many scientists argue that modern plate tectonics started only 2.1 billion y ago (Ga). We document an Archean orogenic eclogite, providing robust evidence that subduction of oceanic crust reached to at least 65 to 70 km in depth at circa 2.5 Ga. This extends the known age of subduction-related eclogite-facies metamorphism back 400 My, showing that modern-style plate tectonics operated by the close of the Archean.

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“…In contrast, IOAS forearc mantle typically consists of extremely depleted harzburgite. Fore-arc spinels (chromite), if unaltered, may preserve very significant petrogenetic information (Dick and Bullen, 1984;Kusky and Glass, 2007;Huang et al, 2021), and have high Cr-number (Cr+Al)>0.4, which can be a great aid in interpreting the tectonic setting of ancient forearc peridotites (e.g., Kusky et al, , 2021bHuang et al, 2017;. Understanding the nature of the mantle beneath the arc axis is hindered by the thickness of the crust in this region, but samples can be obtained from xenoliths (Arai and Ishimaru (2007) and are typically spinel peridotites without garnet that show high degrees of mantle metasomatism, forming secondary orthopyroxene replacing olivine.…”

Section: Components Of Intra-oceanic Arc Systemsmentioning

confidence: 99%

“…Babeyko and Sobolev (2005) suggest that the entire lower crust beneath arcs may behave convectively with crustal overturn facilitating vertical transport of granitoid magmas upwards, and surrounding material downwards (Figure 5), forming the characteristic dome-and-keel structures of continental arcs and some Archean granite greenstone terranes (e.g., the famous domes of Pilbara; . The most common rocks at mid-to deep crustal levels (20-35 km) are mantle-derived melts including amphibole gabbros, horn- Serpentinite plus sediment and metabasalt diapirs likely rise from the subduction channel, bringing additional material from the slab and subducted sediments into the overlying mantle wedge, and may be the source of some arc magmas (e.g., adakites), The diapirs, plus entrained material can in some cases lead to subcrustal relamination, or incorporation of crustal xenocrysts in mantle melts (Kusky et al, 2021b). Mantle wedge corner flow continuously brings new mantle under hypersolidus flow to be metasomatized by the slab-derived fluids (e.g., Zheng, 2019).…”

Section: Crustal Profiles Through Thickened Oceanic and Continental-m...mentioning

confidence: 99%

Growth of continental crust in intra-oceanic and continental-margin arc systems: Analogs for Archean systems

Kusky

Wang

2022

Sci. China Earth Sci.

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Earth's continental crust has grown and been recycled throughout geologic history along convergent plate margins. The main locus of continental crustal growth is in intra-oceanic and continental-margin arc systems in Archean time. In arc systems, oceanic lithosphere is subducted to the deeper mantle, and together with its overlying sedimentary sequence is in some cases off-scraped to form accretionary prisms. Fluids are released from the subducting slab to chemically react with the mantle wedge, forming mafic-ultramafic metasomatites, whose partial melting generates mafic melts that rise up to form arcs. In intraoceanic arcs, they produce dominantly basaltic lavas, with a mid-crust that includes variably-developed vertically-walled intermediate plutons and higher-level dikes and sills. In continental-margin arcs, different petrogenetic processes cause assimilation and fractionation of basaltic magmas, partial melting/reworking of juvenile basaltic rocks, and mixing of mantle-and crust-derived melts, so they produce andesitic calc-alkaline melts but still have a mid-crust dominated by vertically-walled felsic plutons, which form 3-D dome-and-basin structures, akin to those in some Archean terranes such as parts of the Pilbara and Zimbabwe cratons. Notably, the continental crust of Archean times is dominated by tonalite-trondhjemite-granodiorite (TTG) plutons, similar to that of the mid-crust of these arc systems, suggesting that early continental crust may have formed largely by the amalgamation of multiple arc systems. The patterns of magmatism, in terms of petrogenesis, rock types, duration of magmatic and accretionary events, and the spatial scales of deformation and magmatism have remained essentially the same throughout geological history, demonstrating that plate tectonic processes characterized by subduction and arc magmatism have been in operation at least as long as recorded by the preserved geologic record, since the Eoarchean. However, the early Earth was dominated by accretionary orogens and oceanic arcs, that gradually grew thicker through multiple accretion events to form early continental-margin arcs by 3.5-3.2 Ga, and accretionary orogens. Slab melting and warmer metamorphism was more common in Archean arc systems due to higher mantle temperatures. These early arcs were further amalgamated into large emergent continents by ~3.2-3.0 Ga, allowing large-scale processes such as lithospheric rifting and continental collisions, and the start of the supercontinent cycle. Further work should apply the null hypothesis, that plate tectonics explains the geologic record, to test for differences in the style of plate tectonics and magmatism through time, based on the fundamental difference in planetary heat production and the evolution of rotational dynamics of the Earth-Sun-Moon system.

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Ultra-high pressure inclusion in Archean ophiolitic podiform chromitite in mélange block suggests deep subduction on early Earth

Cited by 22 publications

References 81 publications

Diamond and Other Exotic Mineral-Bearing Ophiolites on the Globe: A Key to Understand the Discovery of New Minerals and Formation of Ophiolitic Podiform Chromitite

Diamond and Other Exotic Mineral-Bearing Ophiolites on the Globe: A Key to Understand the Discovery of New Minerals and Formation of Ophiolitic Podiform Chromitite

Archean eclogite-facies oceanic crust indicates modern-style plate tectonics

Growth of continental crust in intra-oceanic and continental-margin arc systems: Analogs for Archean systems

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