Age and petrology of Eocene-Oligocene calc-alkaline volcanism in Biga Peninsula (NW Turkey): Implications for magma origin and geodynamic evolution

Erenoglu O., Bozcu M., Billor M. Z.

JOURNAL OF AFRICAN EARTH SCIENCES, vol.192, pp.1-24, 2022 (SCI-Expanded)

  • Publication Type: Article / Article
  • Volume: 192
  • Publication Date: 2022
  • Doi Number: 10.1016/j.jafrearsci.2022.104559
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aquatic Science & Fisheries Abstracts (ASFA), CAB Abstracts, Geobase, INSPEC
  • Page Numbers: pp.1-24
  • Çanakkale Onsekiz Mart University Affiliated: Yes


In NW Anatolia, Eocene-Oligocene post-collisional volcanism is represented by K-rich volcanic rocks, including

high K calc-alkaline products. Magmatic rocks in the Dededa ̆g area (Biga Peninsula, NW Turkey) can be classified

into 6 different groups with lithostratigraphic and chronostratigraphic data using 40Ar/39Ar methods (Eocene-

early Oligocene, 42.08 ± 0.09 to 29.02 ± 0.29 Ma). From the Eocene period, there are calc-alkaline Laleda ̆g

granodiorite, Beyçayır volcanics with andesite and dacite composition, and also Kızıldam volcanics with alkaline

and basic character (basaltic trachyandesite, trachybasalt). Furthermore, in the Oligocene period, calc-alkaline

volcanism started with Dededa ̆g volcanics with dacite and rhyolite intermediate-acidic composition, continued

with Kırcalar volcanics consisting of basalt and basaltic andesite, and Harmancık volcanics ranging from basalt to

rhyolite. The calc-alkaline Çamyayla pluton with quartz monzonite composition intruded into Oligocene

Dededa ̆g and Harmancık volcanics in the region. Alkaline lavas in the region are classified as high-K and

shoshonitic, and calc-alkaline lavas are medium-high-K. On N-type mid-ocean ridge basalt and chondrite-

normalized trace element diagrams, enrichment was observed for all volcanic units with regard to large ion

lithophile elements and light rare earth elements. High field strength elements and heavy rare earth elements

were depleted in all volcanic units. These compositions reveal the participation of a mantle source that was

enriched by subduction components. Using geochemical data, all the volcanic rocks differentiated as a result of

magma mixing/replenishment and contamination/assimilation processes. Consequently, the source of volcanism

is thought to derive from the compressional regime associated with collision during the Eocene-Oligocene, and

from a previously-enriched lithospheric mantle source with subsequent effects of the extensional regime.