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| Titel |
Petrogenesis of the post-collisional Oligo-Miocene Volcanism in NW Anatolia (Turkey): Balıkesir Volcanites |
| VerfasserIn |
Alp Ünal, Safak Altunkaynak, Jeff A. Benowitz |
| 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 |
250125010
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| Publikation (Nr.) |
 EGU/EGU2016-4533.pdf |
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| Zusammenfassung |
| In this study, we present whole-rock chemical and Sr-Nd-Pb-O isotopic compositions as well
as 40Ar/39Ar ages of Balıkesir volcanites to evaluate the nature, genesis and timing of the
post-collisional Oligo-Miocene magmatism in NW Anatolia.
Three main volcano-stratigraphic groups distinguished in the Balıkesir volcanites on the
basis of field observations and petrographical investigations; 1) andesitic lavas and
related pyroclastic units representing the lower part of the volcanic sequence; 2)
Trachyandesite- basaltic trachyandesite lavas and 3) dacitic lavas and associated pyroclastic
units corresponding to the upper part of the volcanic sequence. Both andesitic and
dacitic pyroclastic units are represented with ash fall, ash block flow and flow breccia
units.
Geochemically, Balıkesir volcanites are ranging in composition from basaltic
trachy-andesite to dacite. They are sub-alkaline in character and show enrichment in large ion
lithophile elements (LILE) and light rare earth elements (LREE) relative to the high field
strength elements (HFSE). Balıkesir volcanites display depletion in P, Ta, Nb and Ti. All
these trace element characteristics and inter-element ratios suggest that magma forming the
Balıkesir volcanites show similar patterns to those of subduction-related arc magmas and/or
post collisional lavas. They have high initial 87Sr/86Sr ratios (0.707109-0.708620), low
143Nd/144Nd (0.512322- 0.512493). 206Pb/204Pb and 207Pb/204Pb values vary from 18.703 to
18.867 and 15.681 to 15.714, respectively and ɛNd values range between -5.61 and -2.27.
18O isotopic ratios range between 8.3 and 11.8. All these isotopic characteristics and
major-trace element compositions of Balıkesir volcanites suggest that the lavas are
co-genetic and originated from a hybrid magma derived from enriched mantle (EM II)
source.
40Ar/39Ar dating yielded isochron ages of 22.9±0.2 – 21.0±0.2 which is consistent with
other volcanic and plutonic associations of western Anatolia (eg. Solarya pluton, Susurluk
volcanites) and the adjacent regions. When the petrological evolution and the age of the
Balıkesir volcanites evaluated together with the general Cenozoic tectonic history of NW
Anatolia, this post-collisional magmatism was most probably the result of partial
delamination or convective removal of the base of mantle lithosphere beneath NW Anatolia. |
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