Initiation of modern-style plate tectonics recorded in Mesoarchean marine chemical sediments

The 700 km-long North Atlantic Craton (NAC) in West Greenland is arguably the best exposed and most continuous section of Eo-to Neoarchaean crust on Earth. This allows a close and essential correlation between geochemical and isotopic data and primary, well-defined and well-studied geological relationships. The NAC is therefore an excellent and unsurpassed stage for the ongoing controversial discussion about uniformitarian versus non-uniformitarian crustal evolution in the Archaean. The latest research on the geochemistry, structural style, and Hf isotope geochemistry of tonalite-trondhjemite-granodiorite (TTG) complexes and their intercalated mafic to intermediate volcanic belts strongly supports previous conclusions that the NAC formed by modern-style plate tectonic processes with slab melting of wet basaltic oceanic crust in island arcs and active continental margins. New studies of the lateral tectonic convergence and collision between juvenile belts in the NAC corroborate this interpretation. Nevertheless, it has repeatedly been hypothesised that the Earth’s crust did not develop by modern-style, subhorizontal plate tectonics before 3.0 Ga, but by vertical processes such as crustal sinking and sagduction, and granitic diapirism with associated dome-and-keel structures. Many of these models are based on supposed inverted crustal density relations, with upper Archaean crust dominated by heavy mafic ridge-lavas and island arcs, and lower Archaean crust mostly consisting of felsic, supposedly buoyant TTGs. Some of them stem from older investigations of upper-crustal Archaean greenstone belts particularly in the Dharwar craton, the Slave and Superior provinces and the Barberton belt. These interpreted interactions between these upper and lower crustal rocks are based on the apparent down-dragged greenstone belts that wrap around diapiric granites. However, in the lower crustal section of the NAC, there is no evidence of any low-density granitic diapirs or heavy, downsagged or sagducted greenstone belts. Instead, the NAC contains well-exposed belts of upper crustal, arc-dominant greenstone belts imbricated and intercalated by well-defined thrusts with the protoliths of the now high-grade TTG gneisses, followed by crustal shortening mainly by folding. This shows us that the upper and lower Archaean crustal components did not interact by vertical diapirism, but by subhorizontal inter-thrusting and folding in an ambient, mainly convergent plate tectonic regime.

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Record of modern-style plate tectonics in the Palaeoproterozoic Trans-Hudson orogen

Nature Geoscience ◽

10.1038/ngeo2904 ◽

2017 ◽

Vol 10 (4) ◽

pp. 305-311 ◽

Cited By ~ 63

Author(s):

O. M. Weller ◽

M. R. St-Onge

Keyword(s):

Plate Tectonics ◽

Modern Style

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The Fuchuan Ophiolite in South China: Evidence for modern‐style plate tectonics during Rodinia breakup

Geochemistry Geophysics Geosystems ◽

10.1029/2021gc010137 ◽

2021 ◽

Author(s):

Si‐Fang Huang ◽

Wei Wang ◽

Andrew C. Kerr ◽

Jun‐Hong Zhao ◽

Qing Xiong ◽

...

Keyword(s):

South China ◽

Plate Tectonics ◽

Modern Style

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A CO2 greenhouse efficiently warmed the early Earth and decreased seawater 18O/16O before the onset of plate tectonics

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2023617118 ◽

2021 ◽

Vol 118 (23) ◽

pp. e2023617118

Author(s):

Daniel Herwartz ◽

Andreas Pack ◽

Thorsten J. Nagel

Keyword(s):

Plate Tectonics ◽

Isotope Composition ◽

Oxygen Isotopic Composition ◽

Early Earth ◽

Time Interval ◽

Hot Climate ◽

Oxygen Isotopic ◽

Low Degrees ◽

Chemical Sediments

The low 18O/16O stable isotope ratios (δ18O) of ancient chemical sediments imply ∼70 °C Archean oceans if the oxygen isotopic composition of seawater (sw) was similar to modern values. Models suggesting lower δ18Osw of Archean seawater due to intense continental weathering and/or low degrees of hydrothermal alteration are inconsistent with the triple oxygen isotope composition (Δ’17O) of Precambrian cherts. We show that high CO2 sequestration fluxes into the oceanic crust, associated with extensive silicification, lowered the δ18Osw of seawater on the early Earth without affecting the Δ’17O. Hence, the controversial long-term trend of increasing δ18O in chemical sediments over Earth’s history partly reflects increasing δ18Osw due to decreasing atmospheric pCO2. We suggest that δ18Osw increased from about −5‰ at 3.2 Ga to a new steady-state value close to −2‰ at 2.6 Ga, coinciding with a profound drop in pCO2 that has been suggested for this time interval. Using the moderately low δ18Osw values, a warm but not hot climate can be inferred from the δ18O of the most pristine chemical sediments. Our results are most consistent with a model in which the “faint young Sun” was efficiently counterbalanced by a high-pCO2 greenhouse atmosphere before 3 Ga.

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Bio-geodynamics of the Earth: State of the art and future directions

10.5194/egusphere-egu2020-10657 ◽

2020 ◽

Author(s):

Taras Gerya ◽

Robert Stern ◽

Loic Pellissier ◽

Dominic Stemmler

Keyword(s):

Plate Tectonics ◽

State Of The Art ◽

Numerical Models ◽

Biological Evolution ◽

Marine Animal ◽

Geodynamic Evolution ◽

Environmental Pressures ◽

Critical Set ◽

Animal Diversity ◽

Modern Style

Geodynamic evolution of Earth&#8217;s mantle and lithosphere is inextricably linked to the evolution of its atmosphere, oceans, landscape and life (e.g., Stern, 2016; Pellissier et al., 2017; Zaffos et al., 2017; Zerkle. 2018). In this context, modern-style plate tectonics that was established gradually through geological time (e.g., Gerya, 2019) is often viewed as a strong promoter of biological evolution (e.g., Pellissier et al., 2017; Zerkle, 2018; Stern, 2016). The influences of this global tectono-magmatic style are at least twofold (e.g., Zerkle, 2018; Stern, 2016). Firstly, life is sustained by a critical set of elements contained within rock, ocean and atmosphere reservoirs and cycled between Earth&#8217;s surface and interior via various tectonic, magmatic and surface processes (Zerkle, 2018); plate tectonics is very effective for this recycling. Second, plate tectonics is an unparalleled agent for redistributing continents and oceans, growing mountain ranges, and forming land bridges, and provides continuous but moderate environmental pressures that isolate and stimulate populations to adapt and evolve (Stern, 2016). Importantly, modern-style plate tectonics itself exerts continuous moderate environmental pressures that drive evolution and stimulate populations to adapt and evolve without being capable of extinguishing all life (Stern 2016). The power of plate tectonics for both nutrient recycling and paleogeographic rededistributions &#160;suggests that a planet with oceans, continents, and modern-style plate tectonics maximizes opportunities for speciation and natural selection, whereas a similar planet without plate tectonics provides fewer such opportunities (Stern, 2016). &#160;The evolution of life must intimately reflect Earth&#8217;s tectonic evolution.It is important to also point out that timescales of biological evolution of complex life estimated on the basis of the analysis of phylogenies and/or fossils are rather long and comparable to geodynamic timescales (e.g., Alroy, 2008; Marshall, 2017). This timescale similarity creates an opportunity for investigating lithospheric and mantle processes with life evolution by developing and testing novel hybrid bio-geodynamical numerical models. These are currently emerging.&#160;Here, we review state of the art for understanding the complex relationship between lithospheric dynamics and life evolution and present some recent examples of numerical modeling studies investigating Earth&#8217;s bio-geodynamic evolution.&#160;References Alroy, J. (2008). Dynamics of origination and extinction in the marine fossil record. Proceedings of the National Academy of Sciences. 105, 11536.Gerya, T. (2019) Geodynamics of the early Earth:&#160; Quest for the missing paradigm. Geology, DOI:10.1130/focus-Oct2019.Marshall, C. R. (2017). Five palaeobiological laws needed to understand the evolution of the living biota. Nature Ecology & Evolution, 1(6), 0165.Pellissier, L., Heine, C., Rosauer, D.F., Albouy, C. (2017)&#160; Are global hotspots of endemic richness shaped by plate tectonics? Biological Journal of the Linnean Society 123 (1), 247-261.Stern, R.J. (2016) Is plate tectonics needed to evolve technological species on exoplanets? Geoscience Frontiers, 7, 573-580.Zaffos, A., Finnegan, S, Peters, S.E. (2017) Plate tectonic regulation of global marine animal diversity. PNAS, 114, 5653&#8211;5658.Zerkle A. L. (2018) Biogeodynamics: bridging the gap between surface and deep Earth processes. Phil. Trans. R. Soc. A 376, 20170401. (doi:10.1098/rsta.2017.0401)

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Feasibility of plate tectonics during the Archean: Insights from 3D numerical thermo-mechanical modelling

10.5194/egusphere-egu2020-13603 ◽

2020 ◽

Author(s):

Andrea Piccolo ◽

Nicholas Arndt ◽

Richard White ◽

Kaus Boris

Keyword(s):

Continental Crust ◽

Plate Tectonics ◽

Large Scale ◽

Driving Forces ◽

Potential Temperature ◽

Geodynamic Setting ◽

Plate Boundaries ◽

Plate Tectonic ◽

Modern Style ◽

Mantle Potential Temperature

Slab-pull forces are considered the major driving forces of the present-day plate tectonic. Their efficiency relies on the buoyancy contrast between asthenosphere and subducting plate and on the strength of the latter. Subduction is not only pivotal for understanding the dynamics of plates but also represents the only modern geodynamic setting that produces significant amount of juvenile continental crust and allows exchange between the mantle, lithosphere and atmosphere.One of the most important unsolved questions is related to the onset of plate tectonics, which is inherently linked to feasibility of the subduction during the early in Earth history. During the Archean, the mantle potential temperature was higher than nowadays, which promoted extensive mantle melting and possibly a weaker lithosphere. The intense magmatism associated with the high mantle potential temperature generated highly residual lithospheric mantle that was more buoyant than the underlying asthenosphere. Altogether these factors may have inhibited the dynamic effect of slab pull and prevented modern style tectonic during the Archean. However, the Archean mantle potential temperature is still not well constrained, and many of these theoretical considerations have not been fully tested by integrating petrological forward modelling into 3D numerical geodynamic modelling.In our contribution, we focus on the feasibility of modern style plate tectonic as a function of the mantle potential temperature and the composition and structure of the lithosphere. We compute representative phase diagrams that represents the composition of mantle lithospheric and its complementary crust as a function of the mantle potential temperature and integrate them into large-scale 3D numerical experiments. The numerical setup is constructed assuming the existence of a set plates interacting with each other. We prescribe the principal plate boundaries and allow the model to spontaneously evolve as function of the thermal ages of the prescribed plate, testing the effect of continental terrains and oceanic plateau on overall geodynamic evolution. The overall goal is to understand the feasibility of plate tectonics at high mantle potential temperature and to estimate the amount of fluid released by the subduction processes, which provide useful insights on the formation of continental crust.

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