1 / 17

Trace elements

Trace elements. Substitutions and partition coefficients Normalization and spidergrams. Fe 2+. Mg 2+. Compatible (right size & charge). Ni 2+. Au 3+. Incompatible (size/charge does not match). Ag 3+. Fe 2+. Mg 2+. Selective affinities. Partition coefficient Kd = C s /C l

kibo-lucas
Télécharger la présentation

Trace elements

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Trace elements

  2. Substitutions and partition coefficients • Normalization and spidergrams

  3. Fe2+ Mg2+ Compatible (right size & charge) Ni2+ Au3+ Incompatible (size/charge does not match) Ag3+ Fe2+ Mg2+ Selective affinities

  4. Partition coefficient Kd = Cs/Cl • Compatible, incompatible (relative to a mineral) • Bulk repartition coefficient D = S Kdi Xi

  5. Compatibility depends on minerals and melts involved. Which are incompatible? Why?

  6. Calculate DYb for… • A lherzolite (80% Ol, 10% Opx, 10%Cpx) • A Grt-bearing Lherzolite (70% Ol, 10% Opx-Cpx-Gt) • Calculate DSr for… • A Cpx-Plag cumulate (50/50) • A Cpx-Opx cumulate (50/50) • How will the residual liquid evolve?

  7. Fingerprinting specific minerals: • Ni strongly fractionated olivine > pyroxene • Cr and Scpyroxenes » olivine • Ni/Cr or Ni/Sc can distinguish the effects of olivine and augite in a partial melt or a suite of rocks produced by fractional crystallization

  8. Concentration of REE in a sample

  9. Chondrites

  10. Contrasted REE patterns Granites Basalts

  11. Multi-elements diagrams Normalized to the PRImitive Mantle (close to chondrites) (Wood version)

  12. Various normalizations: To MORB (Mid-Oceanic Ridge Basalts – the most common type of basalt!) Meaningful for basalts and co.

  13. Various normalizations: To the average continental crust. Meaningful for granites, sediments, etc.

  14. A famous “anomaly”: Eu Granites from the Cape Granite Suite Darling-Vredenburg area

  15. Kd’s for plagioclase • REEs are normally 3+ (La3+, etc.) • Eu can be Eu3+ or Eu2+ • Eu2+ strongly compatible Reducing (Eu2+) Oxydizing (Eu3+)

More Related