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Steven B Shirey Department of Terrestrial Magnetism Carnegie Institution of Washington

Archean Plate Tectonics: Isotopic Evidence from Samples of the Lithospheric Mantle to the Upper Crust. Steven B Shirey Department of Terrestrial Magnetism Carnegie Institution of Washington. DEPTH. ISOTOPIC DATA. INFERENCE. OCEANIC SLAB RECYCLING. Pb-Pb Array for MORB-OIB. CRUSTAL

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Steven B Shirey Department of Terrestrial Magnetism Carnegie Institution of Washington

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  1. Archean Plate Tectonics: Isotopic Evidence from Samples of the Lithospheric Mantle to the Upper Crust Steven B Shirey Department of Terrestrial Magnetism Carnegie Institution of Washington

  2. DEPTH ISOTOPIC DATA INFERENCE OCEANIC SLAB RECYCLING Pb-Pb Array for MORB-OIB CRUSTAL EVIDENCE OCEANIC ARCS WITH START OF CONTINENTAL ARCS Sialic rocks with juvenile isotopes Enriched Os in wet komatiites O isotopes in magmatic zircon EARLY RELATIVELY COOL MAGMATISM Low-T O isotopes in eclogites MANTLE LITHOSPHERE EVIDENCE C & N isotopes in diamond + Os isotopes in sulfide inclusions SUBDUCTION IMPRINT EVIDENT MIF sulfur in sulfide inclusions

  3. Current mantle heterogeneity, especially the Pb-Pb array for MORB-OIB supports Paleoarchean mantle recycling. (Davies, JGR 1984) (Hart & Gaetani, CMP 2006)

  4. (Davies, EPSL 2002)

  5. (Davies, EPSL 2002)

  6. Nd and Hf isotope data on Archean crustal rocks used to require separation on an early crustal component. This is no longer the case. (Vervoort & Blichert-Toft, GCA 2001)

  7. An Early Depleted Reservoir (EDR) has been proposed for the Earth. All Archean crust would come from this reservoir. (Boyet & Carlson, Science, 2005)

  8. EDR of Boyet & Carlson (Bennett, Treatise on Geochemistry, 2004; with additions)

  9. (Bennett, Treatise on Geochemistry, 2004)

  10. EDR of Boyet & Carlson (Bennett, Treatise on Geochemistry, 2004; with additions)

  11. EDR of Boyet & Carlson CRUSTAL EVOLUTION (Harrison et al, Science, 2004; with additions)

  12. Isotopic heterogeneity mantle 4.3 Ga reservoir (Kamber et al, CMP 2003; with additions)

  13. (Valley et al, CMP, 2005)

  14. (modified from Stachel et al, Elements, 2005)

  15. Peridotite Re-Os shows the cratonic lithosphere is Archean Most sulfide inclusions are late Archean (Carlson et al, 1998-2002; James and Fouch, 2002) (Shirey et al., GRL, 2001)

  16. Re, trace elements and oxygen correlate with eclogite groups

  17. Oxygen, Re-Os and REE allow eclogites to be placed into an Archean oceanic lithosphere section

  18. Re-Os whole rock systematics give a scattered Archean age Same for other localities and some other isotope systems (e.g. Nd, Pb)

  19. U-Pb age on zircon supports Re-Os age

  20. (modified from original fig by Schmitz et al, 2004)

  21. Diamond Stable Isotopes (separate symbols are E-Types & fibrous diamonds)

  22. MIF Sulfur (Mojsis et al., GCA, 2003) (Farquhar et al., Science, 2000) An Archean tracer of surficial sulfur

  23. Sulfide inclusions in Orapa diamonds have surface S J. Farquhar et al., Science 298, 2369 -2372 (2002)

  24. Peridotitic Sulfides Sulfides 20 μm Eclogitic Sulfides incident light incident light SE SE CL transmitted

  25. Panda pipe, Slave Craton Age = 3520±170 Ma (Isoplot model 1 MSWD = 0.46) OsIR = 0.1093±0.0001 (Westerlund, Shirey, Richardson, Carlson, Harris, Gurney, CMP, 2006 in press)

  26. Archean (3.5 Ga) example Cenozoic example Mixing of subduction fluids with peridotite in the mantle wedge (Widom, Kepezhinskas, and Defant, Chemical Geology, 2003) (Westerlund, Shirey, Richardson, Carlson, Harris, Gurney, CMP in press)

  27. DEPTH ISOTOPIC DATA INFERENCE OCEANIC SLAB RECYCLING Pb-Pb Array for MORB-OIB CRUSTAL EVIDENCE OCEANIC ARCS WITH START OF CONTINENTAL ARCS Sialic rocks with juvenile isotopes Enriched Os in wet komatiites O isotopes in magmatic zircon EARLY RELATIVELY COOL MAGMATISM Low-T O isotopes in eclogites MANTLE LITHOSPHERE EVIDENCE C & N isotopes in diamond + Os isotopes in sulfide inclusions SUBDUCTION IMPRINT EVIDENT MIF sulfur in sulfide inclusions

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