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| Titel |
Geochemical, isotopic (Sr-Nd-Pb) and geochronological (Ar-Ar and U-Pb) constraints on Quaternary bimodal volcanism of the Nigde Volcanic Complex (Central Anatolia, Turkey) |
| VerfasserIn |
F. Aydin, W. Siebel, I. Uysal, E. Y. Ersoy, A. K. Schmitt, M. Sönmez, R. Duncan |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250071521
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| Zusammenfassung |
| The Nigde Volcanic Complex (NVC) is a major Late Neogene-Quaternary volcanic centre
within the Cappadocian Volcanic Province of Central Anatolia. The Late Neogene evolution
of the NVC generally initiated with the eruption of extensive andesitic-dacitic lavas and
pyroclastic flow deposits, and minor basaltic lavas. This stage was followed by a Quaternary
bimodal magma suite which forms Na-alkaline/transitional basaltic and high-K calc-alkaline
to alkaline silicic volcanic rocks.
In this study, we present new geochemical, isotopic (Sr-Nd-Pb) and geochronological
(Ar-Ar and U-Pb) data for the bimodal volcanic suite within the NVC. Recent data suggest
that the eruption of this suite took place ranges between ~650 and ~220 ka (Middle-Late
Pleistocene). Silicic rocks consisting of rhyolite and associated pumice-rich pyroclastic fall
out and surge deposits define a narrow range of 143Nd/144Nd isotope ratios (0.5126-0.5127),
and show virtually no difference in Pb isotope composition (206Pb/204Pb = 18.84-18.87,
207Pb/204Pb = 15.64-15.67 and 208Pb/204Pb = 38.93-38.99). 87Sr/86Sr isotopic compositions
of the silicic (0.704-0.705) and basaltic rocks (0.703-0.705) are rather similar reflecting a
common source. The most mafic sample from basaltic rocks related to monogenetic cones is
characterized by 87Sr/86Sr = 0.704, 143Nd/144Nd = 0.5127, 206Pb/204Pb = 18.80, 207Pb/204Pb
= 15.60 and 208Pb/204Pb = 38.68. These values suggest a moderately depleted signature of
the mantle source.
The geochronological and geochemical data suggest that NVC silicic and basaltic rocks
are genetically closely related to each other. Mantle derived differentiated basaltic melts
which experienced low degree of crustal assimilation are suggested to be the parent melt of
the rhyolites. Further investigations will focus on the spatial and temporal evolution of
Quaternary bimodal magma suite in the NVC and the genetic relation between silicic and
basaltic rocks through detailed oxygen isotope analysis and (U-Th)/He zircon geochronology. |
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