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Tomas in mine

Tomas Naeraa

Forskare

Tomas in mine

Formation of Archean continental crust constrained by boron isotopes

Författare

  • Mattijs Smit
  • Anders Scherstén
  • Tomas Naeraa
  • Rob Emo
  • Eric Sherer
  • P Sprung
  • Wouter Bleeker
  • Klaus Mezger
  • A Maltese
  • Y Cai
  • E.T. Rasbury
  • Martin J. Whitehouse

Summary, in English

The continental crust grew and matured compositionally during the Palaeo- to Neoarchean through the addition of juvenile tonalite-trondhjemite-granodiorite (TTG) crust. This change has been linked to the start of global plate tectonics, following the general interpretation that TTGs represent ancient analogues of arc magmas. To test this, we analysed B concentrations and isotope compositions in 3.8-2.8 Ga TTGs from different Archean terranes. The 11B/10B values and B concentrations of the TTGs, and their correlation with Zr/Hf, indicate
differentiation from a common B-poor mafic source that did not undergo addition of B from seawater or seawater-altered rocks. The TTGs thus do not resemble magmatic rocks from active margins, which clearly reflect such B addition to their source. The B- and 11B-poor nature of TTGs indicates that modern style subduction may not have been a dominant process in the formation of juvenile continental crust before 2.8 Ga.

Avdelning/ar

  • Berggrundsgeologi

Publiceringsår

2019-11-14

Språk

Engelska

Sidor

23-26

Publikation/Tidskrift/Serie

Geochemical Perspective Letters

Dokumenttyp

Artikel i tidskrift

Förlag

European Association of Geochemistry

Ämne

  • Geology
  • Geochemistry

Nyckelord

  • TTG
  • archean
  • B isotopes
  • crust formation
  • continental crust
  • trace elements
  • archean tectonics

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 2410-3403