Alpine-style nappes thrust over ancient North China continental margin demonstrate large Archean horizontal plate motions

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

et al. 2022

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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.

mentioning

confidence: 99%

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

Ning

Kusky

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

et al. 2022

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“…1.93–1.80 Ga, granulite‐facies metamorphism. We interpret that this Neoarchean tectono‐thermal event was associated with an arc‐continent collisional event along the Zanhuang‐Dongwanzi‐Zunhua ophiolitic mélange to form the Central Orogenic Belt (e.g., T. M. Kusky et al., 2016; T. Kusky et al., 2021, 2022; Ning et al., 2022; J. P. Wang et al., 2017, 2019; Zhong et al., 2021).…”

Section: Discussionmentioning

confidence: 97%

“…Furthermore, the Central Orogenic Belt of the North China craton has been interpreted to reflect the operation of modern‐style plate tectonics, at least at a local scale, by ca. 2.7 Ga (e.g., Zhong et al., 2021, 2022). For the Central Orogenic Belt, Ning et al.…”

Section: Introductionmentioning

confidence: 99%

“…(2022) reported the oldest exposed eclogite‐facies oceanic crust and Huang et al. (2020) documented the occurrence of an Archean paired metamorphic belt, a fundamental characteristic of asymmetric convergent plate boundaries, indicating westward‐directed subduction beneath an intra‐oceanic arc along a ∼1,600‐km‐long belt of accretionary mélange (e.g., T. M. Kusky et al., 2016; T. Kusky et al., 2020; J. P. Wang et al., 2017, 2019; Wu, Wang, et al., 2022; Zhong et al., 2021, 2022). Alternative to interpretations of modern‐style plate tectonic events, researchers have proposed that vertical plume‐related tectonics involving crustal delamination and volcanic resurfacing are evidenced in the Archean–Paleoproterozoic rock record.…”

Section: Introductionmentioning

confidence: 99%

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Paleoproterozoic Plate Tectonics Recorded in the Northern Margin Orogen, North China Craton

Geochem Geophys Geosyst

Zuza

et al. 2022

“…A standard subduction initiation sequence has been established, as a magmatic sequence changing from typical mid-ocean ridge basalts (MORB) through boninite to island arc tholeiite, typically over a short time of a few to tens of millions of years (Reagan et al, 2010(Reagan et al, , 2013(Reagan et al, , 2017Stern et al, 2012;Stern and Gerya, 2018;Maunder et al, 2020). Subduction initiation sequences have now been recognized in many forearc ophiolites in orogens of all ages, from active (Bonin arc, Reagan et al, 2017), to Phanerozoic (Himalaya; Dai et al, 2021), to Archean (Ning et al, 2020;Zhong et al, 2021).…”

Section: Components Of Intra-oceanic Arc Systemsmentioning

confidence: 99%

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

Kusky

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.