40Ar/39Ar Geochronology and Chemical and Isotopic Compositions of Basaltic Rocks Near the Iskenderun Gulf, Turkey

Abstract:

The Iskenderun Gulf in Turkey is the NE limit of the Mediterranean Sea and the general area where the Arabian, African, and Anatolian plates intersect in a diffuse zone of active seismicity and geologically young volcanic activity. This area includes the northern terminus of the N-S striking Dead Sea fault zone as it eventually yields to the NE-SW striking East Anatolian fault zone. Lava flows sampled from this region yield Quaternary ⁴⁰Ar/³⁹Ar ages and have distinct geochemical and isotopic (Sr, Nd, and Pb) compositions, but all the rock samples are consistent with juvenile mantle sources. Most of the volcanism is basaltic, including that in the Karasu rift, which occurs between the Dead Sea fault zone and the East Anatolian fault. Distinctly more alkaline (basanite-tephrite) volcanism is recorded in late-Pleistocene lavas of Delihalil, a volcano situated in close proximity to the East Anatolian fault. The mineralogical, chemical, and isotopic data observed in these lava samples are consistent with small differences in mantle source areas controlled in part by the complex plate boundary configurations defining this area. Our results will be presented within an overall context of evolving plate boundaries, and how the compositions, ages, and isotopic signatures of these volcanic rocks relate to the tectonic escape of the Anatolian plate.