Journal: Precambrian Research

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Elsevier

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0301-9268
1872-7433

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Publications1 - 10 of 36
  • Shallow vs. Deep subduction in Earth history: Contrasting regimes of water recycling into the mantle
    Item type: Journal Article
    Perchuk, Alexei L.; Zakharov, Vladimir S.; Gerya, Taras V.; et al. (2025)
    Precambrian Research
    Water storage capacity of deep Earth mantle minerals allows storing several ocean masses. However, the amount of water delivered to the mantle through geological history remains uncertain because this depends on tectonic style. It also remains unclear how the water storage capacity of oceanic plates and the mode of delivery changed through time and how these variations controlled mantle water content and distribution. Here, we use 2D numerical modeling of subduction styles at different mantle potential temperatures (Tp) corresponding to different stages of the Earth's evolution to show two principal regimes of subduction – shallow flat subduction in the early Earth vs. deep and steep subduction in the modern Earth − that provide contrasting regimes of water recycling into the mantle. Deep and steep subduction occurs at lower mantle potential temperatures (ΔT=0-∼100 °C, Tp compared to today). During the modern regime, abundant water is transported to the mantle transition zone, where some is released from subducted slabs and retained in nominally anhydrous minerals (NAMs, wadsleyite and ringwoodite). Shallow, low angle subduction is obtained in the experiments corresponding to the hotter Precambrian mantle (ΔT=∼150–275 °C, ∼1.5–3.0 Ga), which recycled most water into the shallow (<120 km) mantle. This regime provided cool conditions along the flattened subduction interface with limited slab melting of the mantle wedge. Shallow, flat subduction caused strong hydration of the overriding lithosphere, with water predominantly stored in hydrous minerals (e.g. serpentine, chlorite). Due to the breakdown of hydrous minerals, most of this water was easily returned to the surface and/or was stored in the continental crust. We conclude that if the secular cooling of the Earth's mantle was accompanied by changes in the subduction style from shallow to deep, then it decreased the total volume of oceanic water recycled by subduction but increased the depth of recycling and the average water content in the Mantle Transition Zone. These conclusions pertain to episodes of plate tectonics in Earth history; other modes of water delivery must be considered for single lid tectonic episodes.
  • Redox changes in Early Cambrian black shales at Xiaotan section, Yunnan Province, South China
    Item type: Journal Article
    Och, Lawrence M.; Shields-Zhou, Graham A.; Poulton, Simon W.; et al. (2013)
    Precambrian Research
  • LA-ICP-MS dating of zircons from Meso- and Neoarchean granitoids of the Pietersburg block (South Africa): Crustal evolution at the northern margin of the Kaapvaal craton
    Item type: Journal Article
    Laurent, Oscar; Paquette, Jean-Louis; Martin, Hervé; et al. (2013)
    Precambrian Research
  • Continental subduction recorded by Neoproterozoic eclogite and garnet amphibolites from Western Hoggar (Tassendjanet terrane, Tuareg Shield, Algeria)
    Item type: Other Journal Item
    Berger, Julien; Ouzegane, Kahadidja; Bendaoud, Abderrahmane; et al. (2014)
    Precambrian Research ~ Continental subduction recorded by Neoproterozoic eclogite and garnet amphibolites from Western Hoggar (Tassendjanet terrane, Tuareg Shield, Algeria)
  • Ediacaran glaciations of the west African Craton – Evidence from Morocco
    Item type: Journal Article
    Letsch, Dominik; Large, Simon J.E.; Buechi, Marius W.; et al. (2018)
    Precambrian Research
  • Paleoproterozoic juvenile crust formation and stabilisation in the south-eastern West African Craton (Ghana); New insights from U-Pb-Hf zircon data and geochemistry
    Item type: Journal Article
    Block, Sylvain; Baratoux, Lenka; Zeh, Armin; et al. (2016)
    Precambrian Research
  • Post-Marinoan marine siliciclastic sedimentation
    Item type: Journal Article
    Allen, Philip A.; Leather, Jonathan (2006)
    Precambrian Research
  • Constraining provenance for the uraniferous Paleoproterozoic Francevillian Group sediments (Gabon) with detrital zircon geochronology and geochemistry
    Item type: Journal Article
    Ossa Ossa, Frantz; Hofmann, Axel; Ballouard, Christophe; et al. (2020)
    Precambrian Research
  • Northwest Africa's Ediacaran to early Cambrian fossil record, its oldest metazoans and age constraints for the basal Taroudant Group (Morocco)
    Item type: Journal Article
    Letsch, Dominik; Large, Simon J.E.; Bernasconi, Stefano M.; et al. (2019)
    Precambrian Research
    The Anti-Atlas area in southern Morocco preserves one of the most complete latest Ediacaran to Cambrian shallow-marine carbonate records in the world and serves as a standard for global chemostratigraphic δ13Ccarb curves. Contrary to the excellent chemostratigraphic coverage, neither metazoan fossils (only stromatolites and calcified algae) nor radiometric age constraints were hitherto available for the basal part of this carbonate record, the Tifnout Member of the Adoudou Formation of the Taroudant Group. We report an Ediacara-type fauna from shallow-marine sandstones from the basal Tabia Member and microfossils from dolostones from both the Tabia and the Tifnout members of the Adoudou Formation. The former are discoidal fossils and share many characteristics with the form genus Aspidella and exhibit a peculiar style of preservation, pointing towards an early diagenetic two-stage (carbonate followed by silica) cementation history, leading to good preservation of these supposedly once soft-bodied organisms. The dolostone-hosted microfossils are preserved as sparite-filled molds enclosed by a thin opaque envelope. Despite their small size, they resemble late Ediacaran calcifying metazoans such as Namacalathus and tubular small shelly fossils. Together, these fossils constitute the oldest known direct evidence for presumably metazoan life from Northwest Africa. We also report new time constraints for the Adoudou Formation and fossils enclosed therein based on combined LA-ICP-MS and high-precision CA-ID-TIMS U-Pb zircon geochronology of detrital and volcanic zircons. Together with new chemostratigraphic (δ13Ccarb) and literature data, these new age constraints suggest a late Ediacaran age (time span between ca. 561 and 542 Ma) for the discoidal Ediacara-type fossils from the basal Tabia Member, and a latest Ediacaran to earliest Cambrian (time span between ca. 544 and 540 Ma) and an early Cambrian age (time span between ca. 528 and 523 Ma) for the two microfossil faunas from the Tifnout Member.
Publications1 - 10 of 36