Petrogenesis of plio-quaternary intra-plate continental alkaline lavas from the Iskenderun Gulf (Southern Turkey): Evidence for metasomatized lithospheric mantle


GÜÇTEKİN A.

CHEMIE DER ERDE-GEOCHEMISTRY, cilt.78, ss.521-534, 2018 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 78 Konu: 4
  • Basım Tarihi: 2018
  • Doi Numarası: 10.1016/j.chemer.2018.08.001
  • Dergi Adı: CHEMIE DER ERDE-GEOCHEMISTRY
  • Sayfa Sayısı: ss.521-534

Özet

The Quaternary alkaline volcanic field of Southern Turkey is characterized by infra-continental plate-type magmatic products, exposed to the north of the Iskenderun Gulf along a NE-SW trending East Anatolian Fault, to the west of its intersection with the N-S trending Dead Sea Fault zone. The Iskenderun Gulf alkaline rocks are mostly silica-undersaturated with normative nepheline and olivine and are mostly classified as basanites and alkaline basalts with their low-silica contents ranging between 43 and 48 wt.% SiO2. They display Ocean Island Basalt (OIB)-type trace element patterns characterized by enrichments in large-ion-lithophile elements (LILE) and light rare earth element (LREE), and have (La/Yb)(N) = 8.8-17.7 and (Hf/Sm)(N) = 0.9-1.6 similar to those of basaltic rocks found in intraplate suites. The basanitic rocks have limited variations Sr-Nd isotopic ratios (Sr-87/Sr-86 = 0.70307-0.70324, Nd-143/Nd-144 = 0.512918-0.521947), whereas the alkali basalts display more evolved Sr-Nd isotopic ratios (Sr-87/Sr-86 = 0.70346-0.70365, Nd-143/Nd-144 = 0.512887-0.521896). The Iskenderun Gulf alkaline rocks also display limited Pb isotopic variations with Pb-206/Pb-204 = 18.75-19.09 Pb-207/Pb-204 = 15.61-15.66 and Pb-208/Pb-204 = 38.65-39.02, indicating that they originated from an enriched lithospheric mantle source. Calculated fractionation vectors indicate that clinopyroxene and olivine are the main fractionating mineral phases. Similarly, based on Sr-Nd isotopic ratios, the assimilation and fractional crystallization (AFC) modeling shows that the alkali basalts were affected by AFC processes (r = 0.2) and were slightly contaminated by the upper crustal material.