Mineralogy and Petrology

, Volume 42, Issue 1–4, pp 121–140 | Cite as

Contrasts between platinum group element contents and biotite compositions of Duluth Complex troctolitic and anorthositic series rocks

  • B. Saini-Eidukat
  • P. W. Weiblen
  • G. Bitsianes
  • D. Glascock


This paper presents new data on sulfide assemblages, platinum group elements (PGE's) and halogen contents of biotites in anorthositic series rocks from the Duluth Complex. The data are contrasted with similar data from troctolitic series rocks. Sulfides occur in only trace amounts in anorthositic series rocks as interstitial grains, inclusions in plagioclase, and veinlets cutting olivine. These textures and the sulfide assemblage (pyrrhotite, pentlandite and chalcopyrite) are similar to the sulfide mineralization in troctolitic series rocks. However, the sulfide assemblage is dominated by chalcopyrite in anorthositic rocks. The highest concentration of PGE's in anorthositic series rocks found to date is 163 ppb Pt, with the bulk of the data at limits of detection. PGE contents of troctolitic series rocks range from 100=200 ppb Pt + Pd to an anomalously high 14 ppm Pt + Pd over a one meter interval. The variation of F/Cl ratios with Fe-Mg compositions of Duluth Complex magmatic biotites may be interpreted to imply equilibration with a fluid phase of constant composition. We have no definitive interpretation of the significance of the distinctly different biotite compositions reported from the Stillwater and Bushveld Complexes.


Chalcopyrite Sulfide Mineralization Platinum Group Element Series Rock Bushveld Complex 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Unterschiede der PGE-Gehalte und der Biotitzusammensetzung troktolitischer und anor thositischer Gesteinsserien des Duluth-Komplexes


Diese Arbeit stellt neue Ergebnisse über die Sulfidparagenesen, die Platingruppenelemente (PGE) und die Gehalte an Halogeniden in Biotit aus den anorthositischen Gesteinsserien des Duluth Komplexes vor. Sie werden mit Daten aus den Troktoliten verglichen. Sulfide treten nur im Spuren in den anorthositischen Gesteinen in Form von interstitialen Körnern, von Einschlüssen im Plagioklas und von Olivin durchsetzenden Rissen auf. Diese Texturen und die Sulfidparagenese (Magnetkies, Pentlandit und Kupferkies) sind mit Sulfidmineralisationen in den troktolitischen Gesteinen zu vergleichen. Kupferkies ist allerdings das dominierende Sulfid in den anorthositischen Gesteinen. Die höchsten bis jetzt bekannten PGE-Konzentrationen von 163 ppb Pt sind ebenfalls an diese Gesteine geknüpft. Der Grossteil der Proben zeigt Gehalte im Bereich der Nachweisgrenze. Die PGE-Gehalte der troktolitischen Gesteine schwanken im Bereich von 100–200 ppb Pt und Pd mit über ein Intervall von einem Meter abnormal hohen Gehalten von 14 ppm Pt und Pd.

Die Schwankungen der F/Cl Verhältnisse mit den Fe-Mg Gehalten magmatischer Biotite des Duluth-Komplexes können als Hinweise auf Gleichgewichtsbedingungen mit einer fluiden Phase konstanter Zusammensetzung interpretiert werden.

Die Bedeutung dieser im Vergleich zum Stillwater- und Bushveldkomplex eindeutig verschiedenen Biotitzusammensetzungen ist noch unklar.


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Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • B. Saini-Eidukat
    • 1
  • P. W. Weiblen
    • 1
  • G. Bitsianes
    • 2
  • D. Glascock
    • 3
  1. 1.Newton Horace Winchell School of Earth SciencesDeptartment. of Geology and Geophysics, University of MinnesotaMinneapolisUSA
  2. 2.Mineral Resources Research CenterUniversity of MinnesotaMinneapolisUSA
  3. 3.Reactor Research FacilityUniversity of MissouriColumbiaUSA

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