Advanced luminescence dating of the Karapürçek formation reveals middle pleistocene tectonic reorganization of the North Anatolian Fault Zone
Year: 2025
Type: article
Abstract: This study establishes the first numerical age constraints for the Karapürçek Formation in northwestern Anatolia, Türkiye, using thermally assisted optically stimulated luminescence (TA-OSL) dating. This formation represents the sedimentary fill of a former pull-apart basin and thus records a critical phase in the evolution of the North Anatolian Fault Zone (NAFZ). Four luminescence samples from a 200-meter-thick section yielded ages ranging from ~ 724 ka to ~ 540 ka, constraining deposition of the formation's upper sections to the Middle Pleistocene (Chibanian Stage). The reliability of these Middle Pleistocene ages is underpinned by a detailed signal analysis. This analysis confirms the TA-OSL signal is highly reproducible and exhibits a strong dosimetric response, validating the technique for this challenging geological context. The resulting age-depth model reveals a consistent apparent sedimentation rate of 0.94 mm/year, interpreted as a direct record of steady tectonic subsidence driven by transtensional faulting. Integrating these new ages with the formation's total estimated thickness (1500-1800 m) allows its full depositional lifespan to be constrained from approximately 2.0 to 0.4 Ma. The cessation of deposition is therefore extrapolated to ~ 400 ka, a timing interpreted to mark a major tectonic reorganization. At this point, strain was localized from the older Karapürçek Fault onto the currently active Sapanca-Akyazı segment of the NAFZ, signifying the extinction of the ancestral pull-apart basin. By providing the first complete, multi-million-year timeline for this basin's initiation, evolution, and extinction, this study offers a new quantitative benchmark for understanding the maturation of continental transform faults and for refining long-term seismic hazard models.
Source: Scientific Reports
Authors: Eren Şahiner, Mehmet Korhan Erturaç
Institutions: Ankara University, Gebze Technical University
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,690
Award: G5708453757
OpenAlex ID: W4416679703