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| Titel |
U-Pb Dating, whole rock and Sr-Nd-Pb-O isotope geochemistry of collisional magmatism in the CACC: Çiçekdağ igneous complex (ÇIC) |
| VerfasserIn |
Kiymet Deniz, Yusuf Kagan Kadioglu, Finlay Stuart, Rob Ellam, Adrian Boyce, Daniel Condon |
| 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 |
250101541
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| Publikation (Nr.) |
 EGU/EGU2015-700.pdf |
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| Zusammenfassung |
| The closure of Neotethys induced from calcalkaline through alkaline magmatism within the
Central Anatolia Crystalline Complex (CACC) during the late Cretaceous-early Paleogene.
Timing of these magmatism is very important for understanding the magmato-tectonic
evolution and the relation with the collision. Despite the genesis of felsic products are well
understood, there is lack of petrogenetic explanation about especially alkaline mafic products.
The relation between Neotethyan ophiolites and late alkaline dykes which haven’t reported
before is the most important undeclared gap. Çiçekdağ igneous complex (ÇIC) is one of the
best area for explaining all of these problems within the CACC. In accordance with these
purposes, we have carried out detailed petrographic, whole rock geochemical, Sr-Nd-Pb-O
isotopic and geochronological (U/Pb and Ar/Ar) study of the rocks in the ÇIC in
order to unravel the magmatic history of the CACC and thus constrain the tectonic
history.
The intrusive rocks of the ÇIC are differentiated into four main group as an ophiolites,
calcalkaline series, alkaline series and late alkaline dykes. The felsic and mafic
units intruded to the ophiolitic rocks. The calcalkaline series mostly composed of
monzonites and monzodiorite porphyry whereas the alkaline series consist of syenites and
feldspathoid-bearing gabbros. Variations in the major oxide compositions of both rock series
can be attributed with fractionation of clinopyroxene, plagioclase, amphibole, apatite and iron
titan oxide minerals. The high 87Sr/86Sr and low 143Nd/144Nd of both series are
indicative of mantle sources with large continental crustal components. Feldspar and
quartz oxygen isotope data from calcalkaline and alkaline series have a range of
δ18O values 5.1-11.4o 8.3-9.2‰ and 7.7-14.1o 10.2-13.7‰ respectively and
are compatible with the values for I-A-type granitoids. Both rock series represent
the mixed (mantle-crustal) origin. The combination of all data suggest that these
intrusive rocks have experienced fractional crystallisation coupled with crustal
assimilation.
The calcalkaline and alkaline series show enrichment in LILE and LREE relative to
HFSE and HREE. These rocks have moderate 208Pb/204Pb (38.87-39.16) and 207Pb/204Pb
(15.62-15.71) and high 206Pb/204Pb (18.76-18.81). Both trace element and Pb isotope data
indicate enriched mantle source (EM-II). Mafic alkaline rocks differed with their low
206Pb/204Pb (17.55-17.62). These rocks are derived from subduction modified lithospheric
mantle.
The geochemistry and Sr-Nd-O isotope data of ophiolitic rocks and late alkaline dykes
are very similar. Both of them have flat REE pattern, high 87Sr/86Sr and 143Nd/144Nd, low
δ18O values (1.9-4.0), moderate 208Pb/204Pb (38.81-38.97, 38.51-38.91) and 207Pb/204Pb
(15.62-15.70, 15.54-15.69) and high 206Pb/204Pb (18.37-18.77, 18.39-18.73). All data
indicate heterogeneous mantle source. Trace element ratio diagrams suggest depleted mantle
source and subduction enrichment for late alkaline dykes. Dy versus Dy/Yb diagram
and calculated partial melting curves suggest 20-25% degree of partial melting of
amphibole-phlogopite bearing spinel lherzolitic mantle sources. Ba/Rb versus Rb/Sr diagram
indicate the presence of amphibole in the mantle source of ophiolitic rocks and phlogopite for
the late alkaline dykes.
U-Pb dating of zircon yielded crystallization ages of 73.74±0.027-73.78±0.046 and
73.78±0.071 for calcalkaline series and alkaline series, respectively. Both series are
coexistence and may have coevally been confined from same sources. |
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