Eocene back-arc basin basalt-type diabases from the southern part of the Eastern Pontides (NE Turkey): new evidence for prolonged subduction of Paleo-Tethys oceanic lithosphere
JOURNAL OF THE GEOLOGICAL SOCIETY, cilt.183, sa.4, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 183 Sayı: 4
- Basım Tarihi: 2026
- Doi Numarası: 10.1144/jgs2025-190
- Dergi Adı: JOURNAL OF THE GEOLOGICAL SOCIETY
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Artic & Antarctic Regions, Compendex, Environment Index, Geobase, Zoological Record, Academic Search Ultimate (EBSCO), Natural Science Collection (ProQuest), Earth, Atmospheric, & Aquatic Science Collection (ProQuest), Materials Science & Engineering Collection (ProQuest), Technology Collection (ProQuest)
- Karadeniz Teknik Üniversitesi Adresli: Evet
Özet
The late Mesozoic-early Cenozoic geodynamic evolution of the Eastern Pontides Orogenic Belt (EPOB, NE Turkey) remains a topic of considerable debate. Here we present new geochronological and geochemical data from diabase dykes, sills and stocks intruded into the Pulur metamorphic and Kop ultramafic massifs and their Mesozoic cover rocks in the southern EPOB. Field relationships and zircon U-Pb age determinations reveal that they were emplaced during the late Eocene. These diabase samples show geochemical affinity to back-arc basin basalt (BABB), which originated through decompression melting of a subduction-modified depleted mantle source, and melting was triggered by asthenospheric upwelling in response to roll-back of the Paleo-Tethys lithosphere. The presence of Eocene BABB-type diabases in the southern EPOB challenges the widely accepted idea that the EPOB was shaped by northward subduction of the northern branch of the Neo-Tethys Ocean in the late Mesozoic and its subsequent collision with the Anatolide-Tauride Block at the end of Mesozoic or at the beginning of the Cenozoic. Furthermore, in light of new and published geochemical and geochronological data, we also suggest that the cessation of magmatic activity in the Paleocene is best explained by flat subduction of Paleo-Tethys lithosphere, which was subducted southward at a high angle during the Maastrichtian.