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| Titel |
Petrological constraints on the mantle peridotites from the Cretaceous
ophiolites in southern Turkey and northern Cyprus |
| VerfasserIn |
Özlem Yıldız Yüksekol, Ercan Aldanmaz, Aykut Güçtekin, Douwe J. J. van Hinsbergen, Paul R. D. Mason |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126248
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| Publikation (Nr.) |
 EGU/EGU2016-5945.pdf |
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| Zusammenfassung |
| In this study we present geochemical variations of peridotites from the ophiolite suites
exposed within the Tauride Belt of southern Turkey and in Northern Cyprus with an aim to
document the nature of mantle melting and possible effects of melt movement on element
behavior in supra-subduction zone (SSZ) mantle. The ultramafic rocks representing
the mantle sections of these ophiolites are variably serpentinized spinel–bearing
harzburgites and dunites with major element compositions indicating variable depletions
in basaltic components. Major and trace element systematics of primary mantle
minerals indicate that the peridotites are likely the residual products left behind after
relatively high-degree of mantle melting (16 – 23%). These mantle relicts, however,
display also compositional and textural evidence indicative of extensive melt-rock
interaction. Olivine–orthopyroxene–spinel equilibria indicate that the peridotites are
characterized by high oxygen fugacity (QFM+2), which may be indicative of extensive
interaction of the peridotites with highly oxidized melts. Precise determination of trace
elements from in situ measurements of primary mantle minerals by laser-ablation
ICP-MS reveals important features about the petrogenetic evolution of these mantle
representatives. Trace element signatures in clinopyroxenes indicate that the peridotites are
strongly depleted in Ti and HREE relative to Zr and MLREE, respectively. Uneven
distribution of REE among coexisting opx – cpx pairs in the peridotites reflects chemical
disequilibrium, which can be interpreted to have resulted from either diffusive exchange
during melt movement or interaction with metasomatizing agents. Based on Ga
concentrations and Ga–Ti–Fe+3# variations in chrome-spinels the peridotites have been
inferred to have experienced significant compositional modification through melt-solid
interaction following partial melting. Overall, mineral chemical variations in the
peridotites indicate that the compositions of these depleted mantle relicts cannot be
explained solely by simple mantle melting, but require metasomatic processes with
likely involvement of subduction-related oxidizing melts. Precise compositions
of the mantle and melt components involved, however, differ from one locality
to another, potentially providing opportunity to develop models in understanding
the geodynamic models of melt generation in distinct parts of SSZ environment. |
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