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Petrographic and geochemical characteristics of plagiogranite in the
Yesilova ophiolite between Yesilova and Tefenni (Burdur, SW Turkey)
Fuat COMLEKCILER,
Kerim KOCAK
Selcuk University, Department of Geological Eng, Konya, TURKEY
fuatcomlekciler@selcuk.edu.tr
The
Yesilova ophiolites represent the
western part of the ophiolite belts of the Taurides, SW Turkey. They
mainly consist of mantle-derived
ultramafic tectonite and cumulates, with crustal rocks consisting of
isotropic gabbro, diabase, plagiogranite and sedimentary rocks.
The plagiogranite forms as irregular pods and
netveins within intensively altered cumulate gabbro at the top of the
cumulates. The felsic rocks are composed predominantly subhedral
plagioclase (mostly albite), anhedral quartz and minor amphiboles in a
hypidiomorphic granular texture. At places, granophyric texture
(intergrowth between feldspar and quartz) is also observed. The
ocean-ridge granites (ORG) normalized multi-element spidergrams of the
samples exhibit uniform patterns, with pozitive Ta, Nb, K; and negative
Ba, Ce and Sm anomalies. The primordial mantle normalized multi-element
spidergrams are also characterized by existence of positive U, Nb, K, Pb,
Zr; and negative Ba, La, Ce, P, Eu, Ti anomalies. The REE pattern of
the granite is similar to basic component of the complex, displaying
slight LREE depletion, and mild HREE enrichment. The plagioclase
fractionation in the felsic magma is evidenced by existence of a medium
negative Eu anomaly (Eu/Eu: 0.40-0.51). They differ from the well-known
ophiolite plagiogranites with having relatively higher Ta, Nb; and
lower Ba and Ce contents as well as higher K2O/Rb ratio.
Accordingly, the samples plot onto the field of “within-plate granites”
in various geotectonic diagram based on their immobile element contents.
Moderate K2O content and A/CNK (molar) ratios in the felsic
rocks show similarity to that of continental trondhjemites.
Keywords:
plagiogranite, trondhjemites, ophiolite, Yesilova, Turkey |