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| Titel |
Geochronological and geochemical constraints on the petrogenesis of late Cretaceous volcanic rock series from the eastern Sakarya zone, NE Anatolia-Turkey |
| VerfasserIn |
Faruk Aydin, Simge Oğuz, Cüneyt Şen, İbrahim Uysal, Rasim Baser |
| 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 |
250132565
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| Publikation (Nr.) |
 EGU/EGU2016-13083.pdf |
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| Zusammenfassung |
| New SHRIMP zircon U-Pb ages and whole-rock geochemical data as well as Sr-Nd-Pb
and δ18O isotopes of late Cretaceous volcanic rock series from the Giresun and
Artvin areas (NE Anatolia, Turkey) in the northern part of the eastern Sakarya zone
(ESZ) provide important evidence for northward subduction of the Neo-Tethyan
oceanic lithosphere along the southern border of the ESZ. In particular, tectonic
setting and petrogenesis of these subduction-related volcanites play a critical role in
determining the nature of the lower continental crust and mantle dynamics during late
Mesozoic orogenic processes in this region. The late Cretaceous time in the ESZ is
represented by intensive volcanic activities that occurred in two different periods, which
generally consist of alternation of mafic-intermediate (basaltic to andesitic) and
felsic rock series (dacitic to rhyolitic) within each period. Although there is no
geochronological data for the lower mafic-intermediate rock series of the first volcanic
period, U-Pb zircon dating from the first cycle of felsic rocks yielded ages ranging
from 88.6±1.8 to 85.0±1.3 Ma (i.e. Coniacian-Early Santonian). The first volcanic
period in the region is generally overlain by reddish biomicrite-rich sedimentary
rocks of Santonian-Early Campanian. U-Pb zircon dating for the second cycle of
mafic-intermediate and felsic rocks yielded ages varying from 84.9±1.7 to 80.8±1.5Ma (i.e.
Early to Middle Campanian). The studied volcanic rocks have mostly transitional
geochemical character changing from tholeiitic to calc-alkaline with typical arc signatures.
N-MORB-normalised multi-element and chondrite-normalised rare earth element
(REE) patterns show that all rocks are enriched in LILEs (e.g. Rb, Ba, Th) and
LREEs (e.g. La, Ce) but depleted in Nb and Ti. In particular, the felsic samples are
characterised by distinct negative Eu anomalies. The samples are characterized by a wide
range of Sr-Nd-Pb isotopic compositions (initial ɛNd values from -7.1 to 6.7, initial
87Sr/86Sr from 0.7044 to 0.7075, 206Pb/204Pb from 18.54 to 19.39, 207Pb/204Pb
from 15.56 to 15.66, and 208Pb/204Pb from 38.04 to 39.06). These data together
with δ18O values reflect a genetic relationship between the mafic-intermediate and
felsic volcanic rocks through fractional crystallization process with some crustal
contamination.
Acknowledgments
This study was supported by TUBITAK 112Y365 project. |
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