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Mantle Xenoliths

basalt or granite crust. feldspar. peridotite mantle. Iron. olivine. Chondritic Meteorite. = Sun. + Iron Metal. Mantle Xenoliths. Chondritic Meteorites. Mantle Xenoliths. nephelinite. chondrules. cpx. oliv. opx. Refractory Mantle Residues. Solar Composition.

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Mantle Xenoliths

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  1. basalt or granite crust feldspar peridotite mantle Iron olivine Chondritic Meteorite = Sun + Iron Metal Mantle Xenoliths

  2. Chondritic Meteorites Mantle Xenoliths nephelinite chondrules cpx oliv opx Refractory Mantle Residues Solar Composition

  3. Sun - Chondritic Meteorites - Earth’s Mantle Sun BulkSilicateEarth (~68 wt.%) + Fe-metal core (~31 wt.%) ~ The Earth’s upper mantle is similar in composition to BSE, and is composed of a rock called peridotite, which consists largely of the minerals olivine and orthopyroxene SiO2 + MgO + FeO ~ 91% basalt or granite crust peridotite mantle Fe-Ni metallic core

  4. Igneous Petrology Lab 3: The Mantle Source and Primary Magmas

  5. Calculation for plotting in Olivine – Clinopyroxene – Quartz Liquidus Projection Apatite = P5+ / 3 Cpx (XYT2O6) = X = (Ca2+ + Na+ + K+) - 5 x Apatite Spinel (Y2+Y3+2O4) = Y3+/2 = Cr3+/2 + (Al3+ - 2Ti4+ - Na+)/2 . Opx* (Y2T2O6) = Y/2 = ((Mg2+ + Fe2+ + Mn2+ + Ni2+ + Co2+) - Spin- Cpx)/2 Si* = Si4+ - 2 x Cpx- 2 x Opx*+ Ti4+ If Si* is negative:   Oliv (Y2TO4) = - Si* Si* = 00.00 Opx = Opx* - Oliv If Si* is positive: Qtz = Si* Oliv = 0.0 Opx = Opx* In order to plot your points, orthopyroxene must be recalculated as a mixture of olivine and quartz.

  6. Partial Melting of the Mantle Solid Source Refractory Solid + Liquid Restite Fertile Mantle Refractory Mantle + Oceanic Crust Cpx-rich Peridotite Lherzolite Olivine-rich Peridotite + Basalt Harzburgite Whole = Σ Parts Lever Rule: p/R = x/y amount of basalt (P) in fertile mantle = x/(x+y) ~ 15-20% y x R

  7. opx cpx

  8. Clinopyroxene component calculation Calculate an ideal Cpx formula: XYT2O6: cations sum to 4 Al(1V) = 2 – Si Al(VI) = Al - Al(1V) CrCaTs (CaCrAlSiO6) = Cr AlCaTs (CaAl2SiO6) = Al(VI) – CrCaTs – Na Jadeiite (NaAlSi2O6) = Na Wo (CaSiO3) = (Ca - AlCaTs – CrCaTs)/2 En (MgSiO3) = (1-Wo-Jd) × XMg where XMg = Mg/(Fe+Mg) Fs (FeSiO3) = (1-Wo-Jd) × (1-XMg)

  9. opx cpx

  10. Estimation of Pressure or Depth of Origin

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