<p>Arc environments are locally gold-endowed and it has been long hypothesized that gold mobilization during slab dehydration could affect mantle composition and arc Au-fertility. Here, we determine gold mobility during prograde high pressure-low temperature metamorphism of both metavolcanic and metasedimentary rocks from the islands of Santorini, Ios, Naxos and Syros (Greece). These rocks experienced peak greenschist to upper-blueschist/eclogite facies metamorphism, allowing determination of large-scale gold mobility within a subduction zone. Our data shows that gold is significantly mobilized by fluids at the blueschist-eclogite facies transition. In the associated mélange zones at the slab-mantle interface gold shows heterogeneous concentration but is not enriched, implying only partial retention of gold in the mélange and its mobilization across the slab-mantle interface. Furthermore, the intrinsically complex lithologies and heterogenous gold concentrations of these mélange zones contribute to the slab component inherent to arc magmatism, and can affect magmatism gold-fertility.</p><p></p>

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Gold mobility in subduction zones, the slab perspective

  • Clifford G. C. Patten,
  • Alexandre Peillod,
  • Simon Hector,
  • Barbara I. Kleine-Marshall,
  • Aratz Beranoaguirre,
  • Antonin Bilau,
  • Kirsten Drüppel,
  • Jesse B. Walters,
  • Iain Pitcairn,
  • Uwe Ring,
  • Alasdair Skelton,
  • Jochen Kolb

摘要

Arc environments are locally gold-endowed and it has been long hypothesized that gold mobilization during slab dehydration could affect mantle composition and arc Au-fertility. Here, we determine gold mobility during prograde high pressure-low temperature metamorphism of both metavolcanic and metasedimentary rocks from the islands of Santorini, Ios, Naxos and Syros (Greece). These rocks experienced peak greenschist to upper-blueschist/eclogite facies metamorphism, allowing determination of large-scale gold mobility within a subduction zone. Our data shows that gold is significantly mobilized by fluids at the blueschist-eclogite facies transition. In the associated mélange zones at the slab-mantle interface gold shows heterogeneous concentration but is not enriched, implying only partial retention of gold in the mélange and its mobilization across the slab-mantle interface. Furthermore, the intrinsically complex lithologies and heterogenous gold concentrations of these mélange zones contribute to the slab component inherent to arc magmatism, and can affect magmatism gold-fertility.