Geodynamic Modeling of Late Archean Subduction

Pressure-Temperature Constraints from Greenstone Belt Diamond Deposits

C. O'Neill, D. A. Wyman*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

12 Citations (Scopus)

Abstract

The oldest known diamond deposits occur in 2.7 Ga shoshonitic lamprophyre dikes and breccias in the southern Superior Province, Canada. Given the shallow mantle sources of shoshonite magmas, the diamonds are likely to be subductionrelated. During normal subduction, however, the diamond stability window lies below the source regions of typical shoshonites. Particle-in-cell finite-element modeling of normal and flat subduction indicates that shallow subduction angles optimise the conditions required for a diamond-lamprophyre association. Our results predict diamond formation in parts of the mantle wedge following flat subduction and two generations of diamonds in the subducted slab. Any of these diamond sources may be sampled by lamprophyric magmas during a short-lived period of thermal re-equilibration driven by orogeny. In contrast, normal subduction does not create a mantle wedge diamond population, and long-lived flat subduction without orogeny does not provide a means for lamprophyric magmas to access mantle wedge diamonds.

Original languageEnglish
Title of host publicationArchean Geodynamics and Environments
EditorsKeith Benn, Jean-Claude Mareschal, Kent C. Condie
Place of PublicationWashington, D.C.
PublisherAmerican Geophysical Union
Pages177-188
Number of pages12
ISBN (Electronic)9781118666265
ISBN (Print)9780875904290
DOIs
Publication statusPublished - 18 Mar 2006
Externally publishedYes

Publication series

NameGeophysical Monograph Series
PublisherAmerican Geophysical Union
Volume164
ISSN (Print)0065-8448

Keywords

  • Earth-Crust
  • Earth-Mantle
  • Geodynamics
  • Geology, Stratigraphic-Archaean
  • Geology, Structural
  • Plate tectonics

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    O'Neill, C., & Wyman, D. A. (2006). Geodynamic Modeling of Late Archean Subduction: Pressure-Temperature Constraints from Greenstone Belt Diamond Deposits. In K. Benn, J-C. Mareschal, & K. C. Condie (Eds.), Archean Geodynamics and Environments (pp. 177-188). (Geophysical Monograph Series; Vol. 164). Washington, D.C.: American Geophysical Union. https://doi.org/10.1029/164GM12