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| Titel |
Petrology of high-Cr and high-Al ophiolitic chromitites from the Muğla, SW Turkey: Implications from composition of chromite, solid inclusions of Platinum-group mineral (PGM), silicate, and base-metal mineral (BMM), and Os-isotope geochemistry |
| VerfasserIn |
I. Uysal, M. Tarkian, M. B. Sadiklar, F. Zaccarini, T. Meisel, G. Garuti, S. Heidrich |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250020679
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| Zusammenfassung |
| Ultramafic rocks around the city of Muğla in SW-Turkey are represented by various degree
depleted mantle peridotites ranging from cpx-rich harzburgites to depleted harzburgite and
dunite. Cpx-rich harzburgite are thought to be the residua left after extraction of MORB-type
basalt, from which high-Al chromitite (49.2 < Cr# < 53.5) crystallized with a higher content
of 187Os/188Os (average of 0.1361). However, depleted harzburgites are assumed to be
residua left after extraction of hydrous boninitic melt, produced by second stage partial
melting of already depleted mantle due to subducting slab, from which high-Cr chromitites
(64.2 < Cr# < 85.9) with lower and heterogeneous 187Os/188Os ratio (average of 0.1324)
were crystallized as a result of melt-rock interaction in a suprasubduction environment.
Dunites around the chromite deposits are considered to be the product of melt-peridotite
interaction.
Most of the chromitites contain high-Cr chromite and display enrichment in IPGE (Os, Ir,
Ru) over PPGE (Rh, Pt, Pd), with concentrations of PGE between 61 and 1305 ppb.
Consistently, laurite-erlichmanite serie minerals with various Os concentrations are found to
be the most abundant PGM inclusions in chromite. Os-Ir-Ru alloys, irarsite, kashinite, and
Pt-Fe alloys which is not common in ophiolitic chromitites were also detected as
magmatic PGM inclusions as well as pentlandite, millerite, and rare heazlewoodite as
base metal sulfide. The presence of olivine and clinopyroxene as well as hydrous
silicate inclusions such as amphibole and phlogopite in high-Cr chromitite support
the idea that high-Cr chromitites were formed in a suprasubduction environment. |
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