Yerbilimleri, 22 (2000), 137-148

Hacettepe Üniversitesi Yerbilimleri Uygulama ve Araştırma Merkezi Bülteni

Bulletin of Earth Sciences Application and Research Centre of Hacettepe University

Trace element and Sr-Nd isotope geochemistry of the alkali basalts observed along the Yumurtalık Fault (Adana) in southern Turkey

 

Osman PARLAK

Çukurova Üniversitesi, Jeoloji Mühendisliği Bölümü, 01330 Balcalı-Adana

Michel DELALOYE

University of Geneva, Department of Mineralogy, 1211 Geneva 4, Switzerland

Hüseyin KOZLU

Türkiye Petrolleri Anonim Ortaklığı, Ankara

Denis FONTIGNIE

University of Geneva, Department of Mineralogy, 1211 Geneva 4, Switzerland

  

ABSTRACT

Young volcanics erupted since late Pliocene as a result of lithospheric extension within the transtensional zones along the NE-SW trending letf-lateral Yumurtalik fault zone that mark the boundary between the African and the Anatolian plates in southern Turkey. These volcanics are characterized by alkali olivine basalts. The REE patterns exhibit a strong fractionation characterized by (La/Yb)N ratio between 22 and 6. Primitive mantle normalized incompatible trace element patterns exhibit close similarity to OIB. Ratios of some selected incompatible trace elements (i.e., Ce/Y=1.4-3.8, Zr/Nb=3.9-6.5, La/Ba=0.05-0.1, La/Nb=0.6-0.8, Zr/Ba=0.4-0.8) are also well comparable to those of ocean island basalts. The 87Sr/86Sr ratios show low values (between 0.703081 to 0.703920), whereas the 143Nd/144Nd ratios show high values (ranging from 0.512601 to 0.512986), suggesting an OIB signature. All the evidence suggest that the intracontinental volcanics in this region were derived from an asthenospheric mantle following the fractures of the continental lithosphere that resulted from the left lateral strike-slip fault system bounding the African-Anatolian plates since Late Pliocene in southern Turkey.

Key Words: Adana, alkali basalt, Sr-Nd isotopes, Turkey, Yumurtalık fault

 

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