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Late Quaternary rock uplift rate at the northern margin of the Central Anatolian Plateau: inferences from pediment surfaces and multiple cosmogenic nuclides

Yildirim, C.; Schildgen, T. F.; Echtler, H. P.; Strecker, M. R.; Melnick, D.; Niedermann, S.; Merchel, S.; Martschini, M.; Steier, P.

The northern margin of the Central Anatolian Plateau spans the northward arched part of the Pontide Mountains between the North Anatolian Fault to the south and the Black Sea to the north. Crustal deformation between the North Anatolian Fault and the Black Sea is integrally tied to the evolution of the Central Anatolian Plateau. The asymmetric topographic pattern, coupled with the spatial distribution and geometry of faults, suggest that the northern margin of the plateau has constituted an active accretionary orogenic wedge with northward polarity between the North Anatolian Fault and the abyssal plain of the Black Sea (Figure). To explore the mode and rate of rock uplift that is associated with internal deformation in the accretionary orogenic wedge, we dated incised and deformed pediments by measuring in situ produced 10Be, 21Ne and 36Cl concentrations.
The key target area for our analysis is the Kastamonu intramontane basin. We mapped a suite of six gravel-covered pediment surfaces in the basin that rise 175-180m (P1), 115-130 m (P2), 70-80 m (P3), 45-54 m (P4), 25-35 m (P5) and 12-22 m (P6) above the river. One set of samples was collected along the trunk stream of the Kastamonu basin to estimate trunk stream incision rates, and a second set of samples was collected from local surfaces that have been deformed and incised in response to faulting in the accreationary orogenic wedge.
The surfaces within the basin have exposure ages that range from about. (7.8±0.9) ka to (437 ±64) ka. The temporal distribution of the abandonment ages suggests that specific climatic conditions do not promote abandonment of pediment surfaces in the Kastamonu Basin. The abandonment ages and strath heights of the surfaces yield incision rates that range from 0.20 to 0.49 mm/yr along the trunk stream of the Kastamonu Basin. We used an average fluvial incision rate to calculate rock uplift rate, i.e., incision between the 70-80 m (P2) and 12-22 m (P6) pediments along the trunk stream of the Kastamonu Basin. This gives ~0.27 mm/yr of average vertical rock uplift rate between ca. 437 and 22 ka in the internal part of the Central Pontides.
The highest incision rates (1.04 to 3.16 mm/yr) in the basin are obtained from local surfaces deformed by faults along the basin margins. Topographic profiles across the local pediment surfaces show discernable warping in evidence of out of sequence faulting and partial accommodation of internal deformation in the orogenic wedge. We believe that out-of-sequence faulting and internal deformation indicate a subcritical state of the orogenic wedge at the northern margin of the Central Anatolian Plateau.

Keywords: dating; TCN; in-situ; cosmogenic radionuclides; AMS

  • Poster
    7th TOPO-EUROPE Workshop - A forum investigating the cause and creation of the topography of Europe, 06.-09.10.2011, Davos, Schweiz

Permalink: https://www.hzdr.de/publications/Publ-15867
Publ.-Id: 15867