In northwestern Anatolia,
the ophiolite nappes related with Neotethyan Ocean, the continent
fragments,granitoids and volcanic rocks were found along İzmir - Ankara -
Erzincan Suture Zone (İAEKZ) as a results of thecollision of Sakarya Continent
and Anatolid - Taurid Platform. In northwestern Sivrihisar (Eskiþehir),
phonolitesand trachytes with alkaline characteristic cut the ophiolite nappe.
Late Cretaceous aged ophiolite nappe containing ultramafic - mafic rocks
thrusted over Anatolid - Taurid Platform. Alkaline volcanics were ranged as
domesclose and parallel to the ophiolite thrust line. According to 39Ar/40Ar
geochronological data on phonolites the ageof these rocks are determined as
23-25 Ma (Late Oligocene - Early Miocene). Alkaline volcanics show enrichmentin
LILE (Ba, Sr, Rb, Th) and HFSE (Nb,Ta, Hf, Zr) relative to MORB. Also, light
rare earth elements (LREE) havehigher values than those of HREE values.
However, Pb contents of alkaline rocks are considerably high.According to the
geochemical results, phonolites and trachytes were generated from
asthenospheric magma,enriched with fluid-melting processes linked to the
previous subducted slab. These alkaline lavas have used thedeep strike-slip
faults created by extensional regime during the ascending and have undergone to
a crustal contamination
Birincil Dil | İngilizce |
---|---|
Konular | Mühendislik |
Bölüm | Makaleler |
Yazarlar | |
Yayımlanma Tarihi | 1 Ocak 2006 |
Yayımlandığı Sayı | Yıl 2006 Cilt: 132 Sayı: 132 |
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