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

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

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

(Davies, EPSL 2002)

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)

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

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

(Bennett, Treatise on Geochemistry, 2004)

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

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

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

(Valley et al, CMP, 2005)

(modified from Stachel et al, Elements, 2005)

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

Re, trace elements and oxygen correlate with eclogite groups

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

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

U-Pb age on zircon supports Re-Os age

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

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

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

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

Eclogitic Sulfides 20  m Peridotitic Sulfides Sulfides incident light transmittedCL SE

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

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

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