New He-O-Sr-Nd isotopes and chronology of Quaternary lavas from the Kula volcanic field (western Türkiye): Implications for temporal changes in the magma source

CESUR D., MUTLU H., ALDANMAZ E., Stuart F. M., Carracedo A., Ellam R. M., ...More

Chemical Geology, vol.695, 2025 (SCI-Expanded, Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 695
  • Publication Date: 2025
  • Doi Number: 10.1016/j.chemgeo.2025.123070
  • Journal Name: Chemical Geology
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Aquatic Science & Fisheries Abstracts (ASFA), Artic & Antarctic Regions, Chemical Abstracts Core, Communication Abstracts, Compendex, Metadex, Pollution Abstracts, Civil Engineering Abstracts
  • Keywords: Geochronology, He isotopes, Kula lavas, Lithospheric extension, O isotopes, Western Turkey
  • Middle East Technical University Affiliated: Yes

Abstract

The Quaternary Kula volcanic field in western Turkey comprises predominantly sodium-rich alkaline basaltic products from several eruption periods. We report new bulk-rock major-trace element, Sr Nd isotopes, helium and oxygen isotope determinations of olivine phenocrysts and Ar/Ar and cosmogenic He ages to investigate the mantle source characteristics and the temporal change in melt source isotope compositions. The volcanic activity in the Kula field continued episodically from 1.28 Ma to around 8 ka and can be divided into three main eruption phases characterized by distinct eruption type and lava morphology. The lava compositions from these phases evolve from basanite to phonolitic tephrite. 87 Sr/ 86 Sr and 143 Nd/144Nd range from 0.703012 to 0.703407 and 0.512968 to 0.513032, respectively, becoming less enriched in time. The earliest basalts display a small degree of crustal contamination that reduces with time that may be the result of rapid ascent of magmas in the volcanic conduit, likely resulting from gradually increasing rate of extensional deformation and enhanced lithospheric fracturing.3He/4He ratios vary from 3.50 to 8.04 Ra, while δ18O values vary from 4.7 to 5.2 ‰. The less differentiated samples are characterized by higher3He/4He with >7 Ra, indicating melt derivation from a low-3He/4He OIB-type sub-lithospheric mantle source. The relatively large range in3He/4He and δ18O values with insignificant change in87Sr/86Sr for the entire suite further indicates mixing of melts from a multi-component mantle source.