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| Titel |
Petrogenesis of Post-collisional high Ba-Sr granitoids: the Solarya Pluton, NW Turkey |
| VerfasserIn |
Alp Ünal, Omer Kamaci, Safak Altunkaynak |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107318
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| Publikation (Nr.) |
 EGU/EGU2015-7014.pdf |
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| Zusammenfassung |
| In NW Turkey, the Late Oligocene-Early Miocene phase of post-collisional magmatism is
characterized by widespread granitic pluton emplacements straddling the continental
collision zone marked by the Izmir-Ankara suture zone (IASZ). This granitic magmatism
produced both low Ba-Sr- and high Ba-Sr granitoids with distinct geochemical properties.
One of the major plutons emplaced to the north of Ä°zmir-Ankara suture zone, the
Solarya pluton is representative of high Ba-Sr granitoids. We present here whole-rock
chemical and Sr–Nd–Pb-O isotopic compositions, as well as 40Ar/39Ar ages of the
Solarya pluton to evaluate the timing, nature and genesis of potassic, high Ba-Sr
granites. The Solarya pluton consists of three coeval granitic members (K-Feldspar
megacrystalline granodiorite, fine grained granodiorite and haplogranite) and associated
mafic magmatic enclaves/dykes of gabbroic diorite to dioritic in composition. K-feldspar
megacrystalline granodiorite, fine grained granodiorite and haplogranite are high K
calc-alkaline in character whereas low silica mafic magmatic enclaves and dykes are
mildly alkaline and display shoshonitic affinity. Both granitic members and mafic
enclaves/dykes are characterized by high Ba (710-2489 ppm), Sr (305-708ppm),
low Y and HREE contents and lack of significant negative Eu anomalies. They
are metaluminous and display enrichment in LILE and depletion in P, Ta, Nb and
Ti.
Sr-Nd-Pb and O isotope compositions of mafic enclaves and dykes are similar to their
host granitoids. They have initial 87Sr/86Sr values of 0.70702- 0.70805 and 143Nd/144Nd
values of 0.51235-0.51250 and their ÉNd values range between -4,9 and -2,05. 206Pb/204Pb
and 207Pb/204 Pb isotopic values vary from 18,75 to 18,88 and 15,68 to 15,73, respectivelly.
Whole rock and quartz 18O isotopic ratios range between 8 and 10,6. All these isotopic
characteristics and major-trace element compositions of Solarya pluton and associated mafic
enclaves/dykes suggest a subcontinental litospheric mantle source or depleted mantle source
highly enriched by earlier subduction event(s) for their parental magma. Evolution of parental
magma proceeded by open system processes (AFC and/or mingling) and further fractional
crystallization.
40Ar/39Ar dating yielded isochron ages of 23.2±0.2-21.6±0.4 Ma (Early Miocene),
indicating that cooling of the pluton and exhumation of Kazdağ and Menderes
metamorphic core complexes occurred concurrently. Regarding the Cenozoic tectonic
history of NW Anatolia, not only the age of the Solarya pluton but also inferred
mantle source and magma evolution suggest that the melt generation to produce high
Ba-Sr granitic magmatism was most propably the result of partial delamination
or convective removal of the base of mantle lithosphere beneath NW Anatolia. |
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