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Kharita A, Gilligan A. Cluster Analysis of Velocity Models in Trans-Hudson Bay.. [DOI: 10.1002/essoar.10511462.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
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2
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Kharita A, Gilligan A. Cluster Analysis of Velocity Models in Trans-Hudson Bay.. [DOI: 10.1002/essoar.10511462.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/27/2023]
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Seismic reflections from a lithospheric suture zone below the Archaean Yilgarn Craton. Nat Commun 2021; 12:7245. [PMID: 34903723 PMCID: PMC8668964 DOI: 10.1038/s41467-021-27516-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 11/22/2021] [Indexed: 12/05/2022] Open
Abstract
Seismic reflectors in the uppermost mantle, which can indicate past plate tectonic subduction, are exceedingly rare below Archaean cratons, and restricted to the Neoarchaean. Here we present reprocessed seismic reflection profiles from the northwest Archaean Yilgarn Craton and the Palaeoproterozoic Capricorn Orogen of western Australia that reveal the existence of a ~4 km thick south-dipping band of seismic reflectors that extends from the base of the Archaean crust to at least 60 km depth. We interpret these reflectors, which lie south of a ~50 km deep crustal root, as a relict suture zone within the lithosphere. We suggest that the mantle reflectors were created either by subduction of an oceanic plate along the northern edge of the Yilgarn Craton, which started in the Mesoarchaean and produced the rocks in northern Yilgarn greenstone belts that formed in a supra-subduction zone setting, or, alternatively, by underthrusting of continental crust deep into the lithosphere during the Palaeoproterozoic.
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4
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Oxygen isotopes trace the origins of Earth's earliest continental crust. Nature 2021; 592:70-75. [PMID: 33790444 DOI: 10.1038/s41586-021-03337-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 02/08/2021] [Indexed: 02/01/2023]
Abstract
Much of the current volume of Earth's continental crust had formed by the end of the Archaean eon1 (2.5 billion years ago), through melting of hydrated basaltic rocks at depths of approximately 25-50 kilometres, forming sodic granites of the tonalite-trondhjemite-granodiorite (TTG) suite2-6. However, the geodynamic setting and processes involved are debated, with fundamental questions arising, such as how and from where the required water was added to deep-crustal TTG source regions7,8. In addition, there have been no reports of voluminous, homogeneous, basaltic sequences in preserved Archaean crust that are enriched enough in incompatible trace elements to be viable TTG sources5,9. Here we use variations in the oxygen isotope composition of zircon, coupled with whole-rock geochemistry, to identify two distinct groups of TTG. Strongly sodic TTGs represent the most-primitive magmas and contain zircon with oxygen isotope compositions that reflect source rocks that had been hydrated by primordial mantle-derived water. These primitive TTGs do not require a source highly enriched in incompatible trace elements, as 'average' TTG does. By contrast, less sodic 'evolved' TTGs require a source that is enriched in both water derived from the hydrosphere and also incompatible trace elements, which are linked to the introduction of hydrated magmas (sanukitoids) formed by melting of metasomatized mantle lithosphere. By concentrating on data from the Palaeoarchaean crust of the Pilbara Craton, we can discount a subduction setting6,10-13, and instead propose that hydrated and enriched near-surface basaltic rocks were introduced into the mantle through density-driven convective overturn of the crust. These results remove many of the paradoxical impediments to understanding early continental crust formation. Our work suggests that sufficient primordial water was already present in Earth's early mafic crust to produce the primitive nuclei of the continents, with additional hydrated sources created through dynamic processes that are unique to the early Earth.
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Hawkesworth C, Cawood PA, Dhuime B. The evolution of the continental crust and the onset of plate tectonics. FRONTIERS IN EARTH SCIENCE 2020; 8:326. [PMID: 32944569 PMCID: PMC7116083 DOI: 10.3389/feart.2020.00326] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The Earth is the only known planet where plate tectonics is active, and different studies have concluded that plate tectonics commenced at times from the early Hadean to 700 Ma. Many arguments rely on proxies established on recent examples, such as paired metamorphic belts and magma geochemistry, and it can be difficult to establish the significance of such proxies in a hotter, older Earth. There is the question of scale, and how the results of different case studies are put in a wider global context. We explore approaches that indicate when plate tectonics became the dominant global regime, in part by evaluating when the effects of plate tectonics were established globally, rather than the first sign of its existence regionally. The geological record reflects when the continental crust became rigid enough to facilitate plate tectonics, through the onset of dyke swarms and large sedimentary basins, from relatively high-pressure metamorphism and evidence for crustal thickening. Paired metamorphic belts are a feature of destructive plate margins over the last 700 Myr, but it is difficult to establish whether metamorphic events are associated spatially as well as temporally in older terrains. From 3.8-2.7 Ga, suites of high Th/Nb (subduction-related on the modern Earth) and low Th/Nb (non-subduction-related) magmas were generated at similar times in different locations, and there is a striking link between the geochemistry and the regional tectonic style. Archaean cratons stabilised at different times in different areas from 3.1-2.5 Ga, and the composition of juvenile continental crust changed from mafic to more intermediate compositions. Xenon isotope data indicate that there was little recycling of volatiles before 3 Ga. Evidence for the juxtaposition of continental fragments back to ~2.8 Ga, each with disparate histories highlights that fragments of crust were moving around laterally on the Earth. The reduction in crustal growth at ~ 3 Ga is attributed to an increase in the rates at which differentiated continental crust was destroyed, and that coupled with the other changes at the end of the Archaean are taken to reflect the onset of plate tectonics as the dominant global regime.
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Affiliation(s)
- Chris Hawkesworth
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK
| | - Peter A. Cawood
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia
| | - Bruno Dhuime
- Géosciences Montpellier, CNRS & Université de Montpellier, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
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Brenner AR, Fu RR, Evans DA, Smirnov AV, Trubko R, Rose IR. Paleomagnetic evidence for modern-like plate motion velocities at 3.2 Ga. SCIENCE ADVANCES 2020; 6:eaaz8670. [PMID: 32494654 PMCID: PMC7176424 DOI: 10.1126/sciadv.aaz8670] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 01/30/2020] [Indexed: 06/11/2023]
Abstract
The mode and rates of tectonic processes and lithospheric growth during the Archean [4.0 to 2.5 billion years (Ga) ago] are subjects of considerable debate. Paleomagnetism may contribute to the discussion by quantifying past plate velocities. We report a paleomagnetic pole for the ~3180 million year (Ma) old Honeyeater Basalt of the East Pilbara Craton, Western Australia, supported by a positive fold test and micromagnetic imaging. Comparison of the 44°±15° Honeyeater Basalt paleolatitude with previously reported paleolatitudes requires that the average latitudinal drift rate of the East Pilbara was ≥2.5 cm/year during the ~170 Ma preceding 3180 Ma ago, a velocity comparable with those of modern plates. This result is the earliest unambiguous evidence yet uncovered for long-range lithospheric motion. Assuming this motion is due primarily to plate motion instead of true polar wander, the result is consistent with uniformitarian or episodic tectonic processes in place by 3.2 Ga ago.
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Affiliation(s)
- Alec R. Brenner
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
| | - Roger R. Fu
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
| | - David A.D. Evans
- Department of Geology and Geophysics, Yale University, New Haven, CT, USA
| | - Aleksey V. Smirnov
- Department of Geological and Mining Engineering and Sciences, Michigan Technological University, Houghton, MI, USA
| | - Raisa Trubko
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - Ian R. Rose
- Department of Geology and Geophysics, Yale University, New Haven, CT, USA
- Department of Earth and Planetary Sciences, University of California Berkeley, Berkeley, CA, USA
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7
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Moore EK, Hao J, Spielman SJ, Yee N. The evolving redox chemistry and bioavailability of vanadium in deep time. GEOBIOLOGY 2020; 18:127-138. [PMID: 32048807 DOI: 10.1111/gbi.12375] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 07/22/2019] [Accepted: 11/30/2019] [Indexed: 05/19/2023]
Abstract
The incorporation of metal cofactors into protein active sites and/or active regions expanded the network of microbial metabolism during the Archean eon. The bioavailability of crucial metal cofactors is largely influenced by earth surface redox state, which impacted the timing of metabolic evolution. Vanadium (V) is a unique element in geo-bio-coevolution due to its complex redox chemistry and specific biological functions. Thus, the extent of microbial V utilization potentially represents an important link between the geo- and biospheres in deep time. In this study, we used geochemical modeling and network analysis to investigate the availability and chemical speciation of V in the environment, and the emergence and changing chemistry of V-containing minerals throughout earth history. The redox state of V shifted from a more reduced V(III) state in Archean aqueous geochemistry and mineralogy to more oxidized V(IV) and V(V) states in the Proterozoic and Phanerozoic. The weathering of vanadium sulfides, vanadium alkali metal minerals, and vanadium alkaline earth metal minerals were potential sources of V to the environment and microbial utilization. Community detection analysis of the expanding V mineral network indicates tectonic and redox influence on the distribution of V mineral-forming elements. In reducing environments, energetic drivers existed for V to potentially be involved in early nitrogen fixation, while in oxidizing environments vanadate ( VO43-]]> ) could have acted as a metabolic electron acceptor and phosphate mimicking enzyme inhibitor. The coevolving chemical speciation and biological functions of V due to earth's changing surface redox conditions demonstrate the crucial links between the geosphere and biosphere in the evolution of metabolic electron transfer pathways and biogeochemical cycles from the Archean to Phanerozoic.
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Affiliation(s)
- Eli K Moore
- Department of Environmental Science, School of Earth and the Environment, Rowan University, Glassboro, NJ, USA
| | - Jihua Hao
- University of Lyon, Université Lyon 1, Ens de Lyon, CNRS, Villeurbanne, France
| | - Stephanie J Spielman
- Department of Biological Sciences, College of Science and Mathematics, Rowan University, Glassboro, NJ, USA
| | - Nathan Yee
- School of Biological and Environmental Sciences, Rutgers University, New Brunswick, NJ, USA
- Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ, USA
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8
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Braakman R. Evolution of cellular metabolism and the rise of a globally productive biosphere. Free Radic Biol Med 2019; 140:172-187. [PMID: 31082508 DOI: 10.1016/j.freeradbiomed.2019.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 02/28/2019] [Accepted: 05/02/2019] [Indexed: 01/14/2023]
Abstract
Metabolic processes in cells and chemical processes in the environment are fundamentally intertwined and have evolved in concert for most of Earth's existence. Here I argue that intrinsic properties of cellular metabolism imposed central constraints on the historical trajectories of biopsheric productivity and atmospheric oxygenation. Photosynthesis depends on iron, but iron is highly insoluble under the aerobic conditions produced by oxygenic photosynthesis. These counteracting constraints led to two major stages of Earth oxygenation. After a cyanobacteria-driven biospheric expansion near the Archean-Proterozoic boundary, productivity remained largely restricted to continental boundaries and shallow aquatic environments where weathering inputs made iron more accessible. The anoxic deep open ocean was rich in free iron during the Proterozoic, but this iron was largely inaccessible, partly because an otherwise nutrient-poor ocean was limiting to photosynthesis, but also because a photosynthetic expansion would have quenched its own iron supply. Near the Proterozoic-Phanerozoic boundary, bioenergetics innovations allowed eukaryotic photosynthesis to overcome these interconnected negative feedbacks and begin expanding into the deep open oceans and onto the continents, where nutrients are inherently harder to come by. Key insights into what drove the ecological rise of eukaryotic photosynthesis emerge from analyses of marine Synechococcus and Prochlorococcus, abundant marine picocyanobacteria whose ancestors colonized the oceans in the Neoproterozoic. The reconstructed evolution of this group reveals a sequence of innovations that ultimately produced a form of photosynthesis in Prochlorococcus that is more like that of green plant cells than other cyanobacteria. Innovations increased the energy flux of cells, thereby enhancing their ability to acquire sparse nutrients, and as by-product also increased the production of organic carbon waste. Some of these organic waste products had the ability to chelate iron and make it bioavailable, thereby indirectly pushing the oceans through a transition from an anoxic state rich in free iron to an oxygenated state with organic carbon-bound iron. Resulting conditions (and parallel processes on the continents) in turn led to a series of positive feedbacks that increased the availability of other nutrients, thereby promoting the rise of a globally productive biosphere. In addition to the occurrence of major biospheric expansions, the several hundred million-year periods around the Archean-Proterozoic and Proterozoic-Phanerozoic boundaries share a number of other parallels. Both epochs have also been linked to major carbon cycle perturbations and global glaciations, as well as changes in the nature of plate tectonics and increases in continental exposure and weathering. This suggests the dynamics of life and Earth are intimately intertwined across many levels and that general principles governed transitions in these coupled dynamics at both times in Earth history.
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Affiliation(s)
- Rogier Braakman
- Department of Civil & Environmental Engineering, Massachusetts Institute of Technology, USA; Department of Earth, Atmospheric & Planetary Sciences, Massachusetts Institute of Technology, USA.
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9
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Abstract
The Earth’s continental crust represents the outermost envelope of the solid Earth, controlling exchanges within the geosphere and reflecting geodynamics processes. One of the fundamental issues of Earth Science aims to determine crustal thickness in past geodynamic environments in order to discuss the evolution of certain geodynamic processes through time. Despite presenting a continuing challenge, the evolution of crustal thickness during the last 3 billion years can be investigated using indirect clues yielded by the chemical signature of mafic magmas and associated ferromagnesian minerals (pyroxene, amphibole). Here, we present a new statistical assessment of a global database of magmatic and mineral chemical information. Analysis reveals the increasing occurrence of high-temperature pyroxenes and amphiboles growing in Ca-rich, Fe-poor magma since ~1 Ga, which contrasts with lower temperature conditions of minerals crystallization throughout the Meso- and Palaeoproterozoic times. This is interpreted to reflect temporal changes in the control of Earth’s crust on mantle-derived magma composition, related to changes in lithospheric thickness and mantle secular cooling. We propose that thick existing crust is associated with deeper, hotter magmatic reservoirs, potentially elucidating the mineral chemistry and the contrasting iron content between primary and derivative mafic magmas. Based on both the chemical and mineral information of mafic magma, an integrated approach provides qualitative estimates of past crustal thickness and associated magmatic systems. Our findings indicate that the Proterozoic was characterized by thicker crustal sections (>40–50 km) relative to the Phanerozoic and Archean (<35 km). This period of crustal thickening appears at the confluence of major changes on Earth, marked by the onset of mantle cooling and Plate Tectonics and the assembly of Columbia, the first supercontinent.
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The earliest evidence for modern-style plate tectonics recorded by HP-LT metamorphism in the Paleoproterozoic of the Democratic Republic of the Congo. Sci Rep 2018; 8:15452. [PMID: 30337730 PMCID: PMC6193989 DOI: 10.1038/s41598-018-33823-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/03/2018] [Indexed: 11/29/2022] Open
Abstract
Knowing which geodynamic regimes characterised the early Earth is a fundamental question. This implies to determine when and how modern plate tectonics began. Today, the tectonic regime is dominated by mobile-lid tectonics including deep and cold subduction. However, in the early Earth (4.5 to 2 Ga) stagnant-lid tectonics may also have occurred. The study of high pressure–low temperature (HP–LT) metamorphic rocks is important, because these rocks are only produced in present-day subduction settings. Here, we characterize the oldest known HP–LT eclogite worldwide (2089 ± 13 Ma; 17–23 kbar/500–550 °C), discovered in the Democratic Republic of the Congo. We provide evidence that the mafic protolith of the eclogite formed at 2216 ± 26 Ma in a rift-type basin, and was then subducted to mantle depths (>55 km) before being exhumed during a complete Wilson cycle lasting ca. 130 Ma. Our results indicate the operation of modern mobile-lid plate tectonics at 2.2–2.1 Ga.
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O'Neill C, Turner S, Rushmer T. The inception of plate tectonics: a record of failure. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20170414. [PMID: 30275162 PMCID: PMC6189556 DOI: 10.1098/rsta.2017.0414] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/27/2018] [Indexed: 05/23/2023]
Abstract
The development of plate tectonics from a pre-plate tectonics regime requires both the initiation of subduction and the development of nascent subduction zones into long-lived contiguous features. Subduction itself has been shown to be sensitive to system parameters such as thermal state and the specific rheology. While generally it has been shown that cold-interior high-Rayleigh-number convection (such as on the Earth today) favours plates and subduction, due to the ability of the interior stresses to couple with the lid, a given system may or may not have plate tectonics depending on its initial conditions. This has led to the idea that there is a strong history dependence to tectonic evolution-and the details of tectonic transitions, including whether they even occur, may depend on the early history of a planet. However, intrinsic convective stresses are not the only dynamic drivers of early planetary evolution. Early planetary geological evolution is dominated by volcanic processes and impacting. These have rarely been considered in thermal evolution models. Recent models exploring the details of plate tectonic initiation have explored the effect of strong thermal plumes or large impacts on surface tectonism, and found that these 'primary drivers' can initiate subduction, and, in some cases, over-ride the initial state of the planet. The corollary of this, of course, is that, in the absence of such ongoing drivers, existing or incipient subduction systems under early Earth conditions might fail. The only detailed planetary record we have of this development comes from Earth, and is restricted by the limited geological record of its earliest history. Many recent estimates have suggested an origin of plate tectonics at approximately 3.0 Ga, inferring a monotonically increasing transition from pre-plates, through subduction initiation, to continuous subduction and a modern plate tectonic regime around that time. However, both numerical modelling and the geological record itself suggest a strong nonlinearity in the dynamics of the transition, and it has been noted that the early history of Archaean greenstone belts and trondhjemite-tonalite-granodiorite record many instances of failed subduction. Here, we explore the history of subduction failure on the early Earth, and couple these with insights from numerical models of the geodynamic regime at the time.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
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Affiliation(s)
- Craig O'Neill
- Department of Earth and Planetary Sciences, Macquarie University, North Ryde, Sydney, NSW 2109, Australia
| | - Simon Turner
- Department of Earth and Planetary Sciences, Macquarie University, North Ryde, Sydney, NSW 2109, Australia
| | - Tracy Rushmer
- Department of Earth and Planetary Sciences, Macquarie University, North Ryde, Sydney, NSW 2109, Australia
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12
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Cawood PA, Hawkesworth CJ, Pisarevsky SA, Dhuime B, Capitanio FA, Nebel O. Geological archive of the onset of plate tectonics. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2017.0405. [PMID: 30275157 PMCID: PMC6189553 DOI: 10.1098/rsta.2017.0405] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/21/2018] [Indexed: 05/02/2023]
Abstract
Plate tectonics, involving a globally linked system of lateral motion of rigid surface plates, is a characteristic feature of our planet, but estimates of how long it has been the modus operandi of lithospheric formation and interactions range from the Hadean to the Neoproterozoic. In this paper, we review sedimentary, igneous and metamorphic proxies along with palaeomagnetic data to infer both the development of rigid lithospheric plates and their independent relative motion, and conclude that significant changes in Earth behaviour occurred in the mid- to late Archaean, between 3.2 Ga and 2.5 Ga. These data include: sedimentary rock associations inferred to have accumulated in passive continental margin settings, marking the onset of sea-floor spreading; the oldest foreland basin deposits associated with lithospheric convergence; a change from thin, new continental crust of mafic composition to thicker crust of intermediate composition, increased crustal reworking and the emplacement of potassic and peraluminous granites, indicating stabilization of the lithosphere; replacement of dome and keel structures in granite-greenstone terranes, which relate to vertical tectonics, by linear thrust imbricated belts; the commencement of temporally paired systems of intermediate and high dT/dP gradients, with the former interpreted to represent subduction to collisional settings and the latter representing possible hinterland back-arc settings or ocean plateau environments. Palaeomagnetic data from the Kaapvaal and Pilbara cratons for the interval 2780-2710 Ma and from the Superior, Kaapvaal and Kola-Karelia cratons for 2700-2440 Ma suggest significant relative movements. We consider these changes in the behaviour and character of the lithosphere to be consistent with a gestational transition from a non-plate tectonic mode, arguably with localized subduction, to the onset of sustained plate tectonics.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
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Affiliation(s)
- Peter A Cawood
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia
- Department of Earth Sciences, University of St Andrews, St Andrews, Fife KY16 9AL, UK
| | - Chris J Hawkesworth
- Department of Earth Sciences, University of St Andrews, St Andrews, Fife KY16 9AL, UK
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK
| | - Sergei A Pisarevsky
- ARC Centre of Excellence for Core to Crust Fluid Systems (CCFS) and Earth Dynamics Research Group, The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University, GPO Box U1987, Perth, WA 6845, Australia
| | - Bruno Dhuime
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK
- CNRS-UMR 5243, Géosciences Montpellier, Université de Montpellier, Montpellier, France
| | - Fabio A Capitanio
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia
| | - Oliver Nebel
- School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia
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Nebel O, Capitanio FA, Moyen JF, Weinberg RF, Clos F, Nebel-Jacobsen YJ, Cawood PA. When crust comes of age: on the chemical evolution of Archaean, felsic continental crust by crustal drip tectonics. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:rsta.2018.0103. [PMID: 30275165 PMCID: PMC6189554 DOI: 10.1098/rsta.2018.0103] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 08/10/2018] [Indexed: 05/18/2023]
Abstract
The secular evolution of the Earth's crust is marked by a profound change in average crustal chemistry between 3.2 and 2.5 Ga. A key marker for this change is the transition from Archaean sodic granitoid intrusions of the tonalite-trondhjemite-granodiorite (TTG) series to potassic (K) granitic suites, akin (but not identical) to I-type granites that today are associated with subduction zones. It remains poorly constrained as to how and why this change was initiated and if it holds clues about the geodynamic transition from a pre-plate tectonic mode, often referred to as stagnant lid, to mobile plate tectonics. Here, we combine a series of proposed mechanisms for Archaean crustal geodynamics in a single model to explain the observed change in granitoid chemistry. Numeric modelling indicates that upper mantle convection drives crustal flow and subsidence, leading to profound diversity in lithospheric thickness with thin versus thick proto-plates. When convecting asthenospheric mantle interacts with lower lithosphere, scattered crustal drips are created. Under increasing P-T conditions, partial melting of hydrated meta-basalt within these drips produces felsic melts that intrude the overlying crust to form TTG. Dome structures, in which these melts can be preserved, are a positive diapiric expression of these negative drips. Transitional TTG with elevated K mark a second evolutionary stage, and are blends of subsided and remelted older TTG forming K-rich melts and new TTG melts. Ascending TTG-derived melts from asymmetric drips interact with the asthenospheric mantle to form hot, high-Mg sanukitoid. These melts are small in volume, predominantly underplated, and their heat triggered melting of lower crustal successions to form higher-K granites. Importantly, this evolution operates as a disseminated process in space and time over hundreds of millions of years (greater than 200 Ma) in all cratons. This focused ageing of the crust implies that compiled geochemical data can only broadly reflect geodynamic changes on a global or even craton-wide scale. The observed change in crustal chemistry does mark the lead up to but not the initiation of modern-style subduction.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
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Affiliation(s)
- O Nebel
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | - F A Capitanio
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | - J-F Moyen
- Laboratoire Magmas et Volcans, Université de Lyon, UJM-UCA-CNRS-IRD, 23 rue Dr. Paul Michelon, 42023 Saint Etienne, France
| | - R F Weinberg
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | - F Clos
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
| | | | - P A Cawood
- School of Earth, Atmosphere and Environment, Monash University, Clayton, 3800 Victoria, Australia
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14
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Nebel-Jacobsen Y, Nebel O, Wille M, Cawood PA. A non-zircon Hf isotope record in Archean black shales from the Pilbara craton confirms changing crustal dynamics ca. 3 Ga ago. Sci Rep 2018; 8:922. [PMID: 29343835 PMCID: PMC5772043 DOI: 10.1038/s41598-018-19397-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 12/27/2017] [Indexed: 11/22/2022] Open
Abstract
Plate tectonics and associated subduction are unique to the Earth. Studies of Archean rocks show significant changes in composition and structural style around 3.0 to 2.5 Ga that are related to changing tectonic regime, possibly associated with the onset of subduction. Whole rock Hf isotope systematics of black shales from the Australian Pilbara craton, selected to exclude detrital zircon components, are employed to evaluate the evolution of the Archean crust. This approach avoids limitations of Hf-in-zircon analyses, which only provide input from rocks of sufficient Zr-concentration, and therefore usually represent domains that already underwent a degree of differentiation. In this study, we demonstrate the applicability of this method through analysis of shales that range in age from 3.5 to 2.8 Ga, and serve as representatives of their crustal sources through time. Their Hf isotopic compositions show a trend from strongly positive εHfinitial values for the oldest samples, to strongly negative values for the younger samples, indicating a shift from juvenile to differentiated material. These results confirm a significant change in the character of the source region of the black shales by 3 Ga, consistent with models invoking a change in global dynamics from crustal growth towards crustal reworking around this time.
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Affiliation(s)
- Yona Nebel-Jacobsen
- Isotopia Laboratory, School of Earth Atmosphere and Environment, Monash University, 9 Rainforest Walk, VIC 3800, Clayton/Melbourne, Australia.
| | - Oliver Nebel
- Isotopia Laboratory, School of Earth Atmosphere and Environment, Monash University, 9 Rainforest Walk, VIC 3800, Clayton/Melbourne, Australia
| | - Martin Wille
- Department of Geoschience, University of Tübingen, Wilhelmstraße 56, 72076, Tübingen, Germany.,Institute of Geological Sciences, University of Bern, Baltzerstrasse 1-3, 3012, Bern, Switzerland
| | - Peter A Cawood
- Isotopia Laboratory, School of Earth Atmosphere and Environment, Monash University, 9 Rainforest Walk, VIC 3800, Clayton/Melbourne, Australia
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Hays LE, Graham HV, Des Marais DJ, Hausrath EM, Horgan B, McCollom TM, Parenteau MN, Potter-McIntyre SL, Williams AJ, Lynch KL. Biosignature Preservation and Detection in Mars Analog Environments. ASTROBIOLOGY 2017; 17:363-400. [PMID: 28177270 PMCID: PMC5478115 DOI: 10.1089/ast.2016.1627] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
This review of material relevant to the Conference on Biosignature Preservation and Detection in Mars Analog Environments summarizes the meeting materials and discussions and is further expanded upon by detailed references to the published literature. From this diverse source material, there is a detailed discussion on the habitability and biosignature preservation potential of five primary analog environments: hydrothermal spring systems, subaqueous environments, subaerial environments, subsurface environments, and iron-rich systems. Within the context of exploring past habitable environments on Mars, challenges common to all of these key environments are laid out, followed by a focused discussion for each environment regarding challenges to orbital and ground-based observations and sample selection. This leads into a short section on how these challenges could influence our strategies and priorities for the astrobiological exploration of Mars. Finally, a listing of urgent needs and future research highlights key elements such as development of instrumentation as well as continued exploration into how Mars may have evolved differently from Earth and what that might mean for biosignature preservation and detection. Key Words: Biosignature preservation-Biosignature detection-Mars analog environments-Conference report-Astrobiological exploration. Astrobiology 17, 363-400.
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Affiliation(s)
- Lindsay E. Hays
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
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O’Neill C, Lenardic A, Condie KC. Earth's punctuated tectonic evolution: cause and effect. ACTA ACUST UNITED AC 2013. [DOI: 10.1144/sp389.4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractPeaks in the Precambrian preserved crustal record are associated with major volcanic, tectonic and climatic events. These include addition of juvenile continental crust, voluminous high-temperature volcanism, massive mantle depletion, widespread orogeny and mineralization, large apparent polar wander velocity spikes, and subsequent palaeomagnetic intensity increases. These events impinge on the glaciation record, atmospheric and ocean chemistry, and on the rise of oxygen. Here we summarize and assess a number of geodynamic models that have been proposed to explain the observed episodicity in the Precambrian record. We find that episodic behaviour from nonlinear slab-driven models best explains the observed record. Examples of such slab-driven systems include mantle avalanches or episodic subduction. In these cases, rapid descent of slabs into the mantle drives fast plate motions and convergence at the surface. This is accompanied by large-scale upwellings of deep hot mantle, which contribute to voluminous volcanism. Further modelling will determine the relative importance of each mechanism, and reinforce the fundamental contribution of the mantle to the evolution of Earth's surface systems.
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Affiliation(s)
- C. O’Neill
- CCFS ARC Centre of Excellence, GEMOC, Macquarie University, Sydney, Australia
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17
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Cawood PA, Hawkesworth CJ. Temporal relations between mineral deposits and global tectonic cycles. ACTA ACUST UNITED AC 2013. [DOI: 10.1144/sp393.1] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractMineral deposits are heterogeneously distributed in both space and time, with variations reflecting tectonic setting, evolving environmental conditions, as in the atmosphere and hydrosphere, and secular changes in the Earth's thermal history. The distribution of deposit types whose settings are tied to plate margin processes (e.g. orogenic gold, volcanic-hosted massive sulphide, Mississippi valley type Pb–Zn deposits) correlates well with the supercontinent cycle, whereas deposits related to intra-cratonic settings and mantle-driven igneous events, such as Ni–Cu–PGE deposits, lack a clear association. The episodic distribution of deposits tied to the supercontinent cycle is accentuated by selective preservation and biasing of rock units and events during supercontinent assembly, a process that encases the deposit within the assembled supercontinent and isolates it from subsequent removal and recycling at plate margins.
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Affiliation(s)
- Peter A. Cawood
- Department of Earth Sciences, University of St Andrews, Irvine Building, North Street, St Andrews, Fife KY16 9AL, UK
- Centre for Exploration Targeting, School of Earth and Environment, The University of Western Australia, Crawley, WA 6009, Australia
| | - Chris J. Hawkesworth
- Department of Earth Sciences, University of St Andrews, Irvine Building, North Street, St Andrews, Fife KY16 9AL, UK
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Dhuime B, Hawkesworth CJ, Cawood PA, Storey CD. A change in the geodynamics of continental growth 3 billion years ago. Science 2012; 335:1334-6. [PMID: 22422979 DOI: 10.1126/science.1216066] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Models for the growth of continental crust rely on knowing the balance between the generation of new crust and the reworking of old crust throughout Earth's history. The oxygen isotopic composition of zircons, for which uranium-lead and hafnium isotopic data provide age constraints, is a key archive of crustal reworking. We identified systematic variations in hafnium and oxygen isotopes in zircons of different ages that reveal the relative proportions of reworked crust and of new crust through time. Growth of continental crust appears to have been a continuous process, albeit at variable rates. A marked decrease in the rate of crustal growth at ~3 billion years ago may be linked to the onset of subduction-driven plate tectonics.
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Affiliation(s)
- Bruno Dhuime
- Department of Earth Sciences, University of St. Andrews, St. Andrews, UK.
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Reddy SM, Evans DAD. Palaeoproterozoic supercontinents and global evolution: correlations from core to atmosphere. ACTA ACUST UNITED AC 2009. [DOI: 10.1144/sp323.1] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractThe Palaeoproterozoic era was a time of profound change in Earth evolution and represented perhaps the first supercontinent cycle, from the amalgamation and dispersal of a possible Neoarchaean supercontinent to the formation of the 1.9–1.8 Ga supercontinent Nuna. This supercontinent cycle, although currently lacking in palaeogeographic detail, can in principle provide a contextual framework to investigate the relationships between deep-Earth and surface processes. In this article, we graphically summarize secular evolution from the Earth's core to its atmosphere, from the Neoarchaean to the Mesoproterozoic eras (specifically 3.0–1.2 Ga), to reveal intriguing temporal relationships across the various ‘spheres’ of the Earth system. At the broadest level our compilation confirms an important deep-Earth event at c. 2.7 Ga that is manifested in an abrupt increase in geodynamo palaeointensity, a peak in the global record of large igneous provinces, and a broad maximum in several mantle-depletion proxies. Temporal coincidence with juvenile continental crust production and orogenic gold, massive-sulphide and porphyry copper deposits, indicate enhanced mantle convection linked to a series of mantle plumes and/or slab avalanches. The subsequent stabilization of cratonic lithosphere, the possible development of Earth's first supercontinent and the emergence of the continents led to a changing surface environment in which voluminous banded iron-formations could accumulate on the continental margins and photosynthetic life could flourish. This in turn led to irreversible atmospheric oxidation at 2.4–2.3 Ga, extreme events in global carbon cycling, and the possible dissipation of a former methane greenhouse atmosphere that resulted in extensive Palaeoproterozoic ice ages. Following the great oxidation event, shallow marine sulphate levels rose, sediment-hosted and iron-oxide-rich metal deposits became abundant, and the transition to sulphide-stratified oceans provided the environment for early eukaryotic evolution. Recent advances in the geochronology of the global stratigraphic record have made these inferences possible. Frontiers for future research include more refined modelling of Earth's thermal and geodynamic evolution, palaeomagnetic studies of geodynamo intensity and continental motions, further geochronology and tectonic syntheses at regional levels, development of new isotopic systems to constrain geochemical cycles, and continued innovation in the search for records of early life in relation to changing palaeoenvironments.
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Affiliation(s)
- S. M. Reddy
- The Institute for Geoscience Research, Department of Applied Geology, Curtin University of Technology, GPO Box U 1987, Perth, WA 6845, Australia
| | - D. A. D. Evans
- Department of Geology and Geophysics, Yale University, New Haven, CT 06520-8109, USA
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Destruction geodynamics of the North China craton and its Paleoproterozoic plate tectonics. Sci Bull (Beijing) 2009. [DOI: 10.1007/s11434-009-0451-5] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Scholl DW, von Huene R. Implications of estimated magmatic additions and recycling losses at the subduction zones of accretionary (non-collisional) and collisional (suturing) orogens. ACTA ACUST UNITED AC 2009. [DOI: 10.1144/sp318.4] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractArc magmatism at subduction zones (SZs) most voluminously supplies juvenile igneous material to build rafts of continental and intra-oceanic or island arc (CIA) crust. Return or recycling of accumulated CIA material to the mantle is also most vigorous at SZs. Recycling is effected by the processes of sediment subduction, subduction erosion, and detachment and sinking of deeply underthrust sectors of CIA crust. Long-term (>10–20 Ma) rates of additions and losses can be estimated from observational data gathered where oceanic crust underruns modern, long-running (Cenozoic to mid-Mesozoic) ocean-margin subduction zones (OMSZs, e.g. Aleutian and South America SZs). Long-term rates can also be observationally assessed at Mesozoic and older crust-suturing subduction zone (CSSZs) where thick bodies of CIA crust collided in tectonic contact (e.g. Wopmay and Appalachian orogens, India and SE Asia). At modern OMSZs arc magmatic additions at intra-oceanic arcs and at continental margins are globally estimated atc. 1.5 AU andc. 1.0 AU, respectively (1 AU, or Armstrong Unit,=1 km3a−1of solid material). During collisional suturing at fossil CSSZs, global arc magmatic addition is estimated at 0.2 AU. This assessment presumes that in the past the global length of crustal collision zones averagedc. 6000 km, which is one-half that under way since the early Tertiary. The average long-term rate of arc magmatic additions extracted from modern OMSZs and older CSSZs is thus evaluated at 2.7 AU. Crustal recycling at Mesozoic and younger OMSZs is assessed atc. 60 km3Ma−1km−1(c. 60% by subduction erosion). The corresponding global recycling rate isc. 2.5 AU. At CSSZs of Mesozoic, Palaeozoic and Proterozoic age, the combined upper and lower plate losses of CIA crust via subduction erosion, sediment subduction, and lower plate crustal detachment and sinking are assessed far less securely atc. 115 km3Ma−1km−1. At a global length of 6000 km, recycling at CSSZs is accordinglyc. 0.7 AU. The collective loss of CIA crust estimated for modern OMSZs and for older CSSZs is thus estimated atc. 3.2 AU. SZ additions (+2.7 AU) and subtractions (−3.2 AU) are similar. Because many uncertainties and assumptions are involved in assessing and applying them to the deep past, the net growth of CIA crust during at least Phanerozoic time is viewed as effectively nil. With increasing uncertainty, the long-term balance can be applied to the Proterozoic, but not before the initiation of the present style of subduction atc. 3 Ga. Allowing that since this time a rounded-down rate of recycling of 3 AU is applicable, a startlingly high volume of CIA crust equal to that existing now has been recycled to the mantle. Although the recycled volume (c. 9×109km3) is small (c. 1%) compared with that of the mantle, it is large enough to impart to the mantle the signature of recycled CIA crust. Because subduction zones are not spatially fixed, and their average global lengths have episodically been less or greater than at present, recycling must have contributed significantly to creating recognized heterogeneities in mantle geochemistry.
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Affiliation(s)
- David W. Scholl
- University of Alaska Fairbanks, Fairbanks, AK 99775, USA
- U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
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Cawood PA, Kröner A, Collins WJ, Kusky TM, Mooney WD, Windley BF. Accretionary orogens through Earth history. ACTA ACUST UNITED AC 2009. [DOI: 10.1144/sp318.1] [Citation(s) in RCA: 570] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AbstractAccretionary orogens form at intraoceanic and continental margin convergent plate boundaries. They include the supra-subduction zone forearc, magmatic arc and back-arc components. Accretionary orogens can be grouped into retreating and advancing types, based on their kinematic framework and resulting geological character. Retreating orogens (e.g. modern western Pacific) are undergoing long-term extension in response to the site of subduction of the lower plate retreating with respect to the overriding plate and are characterized by back-arc basins. Advancing orogens (e.g. Andes) develop in an environment in which the overriding plate is advancing towards the downgoing plate, resulting in the development of foreland fold and thrust belts and crustal thickening. Cratonization of accretionary orogens occurs during continuing plate convergence and requires transient coupling across the plate boundary with strain concentrated in zones of mechanical and thermal weakening such as the magmatic arc and back-arc region. Potential driving mechanisms for coupling include accretion of buoyant lithosphere (terrane accretion), flat-slab subduction, and rapid absolute upper plate motion overriding the downgoing plate. Accretionary orogens have been active throughout Earth history, extending back until at least 3.2 Ga, and potentially earlier, and provide an important constraint on the initiation of horizontal motion of lithospheric plates on Earth. They have been responsible for major growth of the continental lithosphere through the addition of juvenile magmatic products but are also major sites of consumption and reworking of continental crust through time, through sediment subduction and subduction erosion. It is probable that the rates of crustal growth and destruction are roughly equal, implying that net growth since the Archaean is effectively zero.
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Affiliation(s)
- Peter A. Cawood
- School of Earth and Environment, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Alfred Kröner
- Institut für Geowissenschaften, Universität Mainz, 55099 Mainz, Germany
| | - William J. Collins
- School of Earth Sciences, James Cook University, Townsville, Qld 4811, Australia
| | - Timothy M. Kusky
- Department of Earth and Atmospheric Sciences, St. Louis University, St. Louis, MO 63103, USA
| | - Walter D. Mooney
- US Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, USA
| | - Brian F. Windley
- Department of Geology, University of Leicester, Leicester LE1 7RH, UK
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Stern RJ. When and how did plate tectonics begin? Theoretical and empirical considerations. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s11434-007-0073-8] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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