Browsing by Author "van Hinsbergen, Douwe J. J."

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Late Neogene Oroclinal Bending in the Central Taurides: a Record of Terminal Eastward Subduction in Southern Turkey
(Elsevier Science Bv, 2016) Koc, Ayten; van Hinsbergen, Douwe J. J.; Kaymakci, Nuretdin; Langereis, Cornelis G.
The Tauride fold-thrusts belt formed during similar to S-N convergence between Africa and Eurasia since Cretaceous time. The western end of the central Taurides strike NW-SE, highly obliquely to the overall convergence direction, and connect to the NE-SW Beydaglan-Lycian Nappe flank of the western Taurides, forming the so-called 'Isparta Angle'. In Neogene time, the western and central Taurides and the inner part of the Isparta Angle became overlain by Neogene sedimentary basins including Manavgat, Koprucay and Aksu, characterized by marine clastics and carbonates. The eastern limb of the Isparta Angle experienced multidirectional Miocene to Present extension, whereas E-W shortening affected the marine sedimentary basins in the heart of the Isparta Angle. To quantitatively reconstruct the Neogene kinematic evolution of the Taurides, towards restoring the subduction system accommodating Africa-Eurasia convergence, we paleomagnetically assess if and when vertical axis rotations affected the Manavgat, Koprucay, and Aksu basins in Early Miocene to Pliocene times. We show that the northern Koprucay Basin rotated similar to 20-30 degrees clockwise, the Manavgat Basin underwent similar to 25-35 degrees counterclockwise rotation, and the Aksu Basin underwent no rotation since the Early-Middle Miocene. It was previously shown that the Beydaglari region underwent a post-Middle Miocene similar to 20 degrees counterclockwise rotation. These results show that the prominent oroclinal salient geometry of the western Taurides thus acquired, at least in part, since Miocene times, that the Koprucay Basin rotated relative to the Aksu Basin along the Aksu thrust, and that the Beydaglari platform rotated relative to the Aksu Basin along the Bucak thrust, which must have both been active until Late Neogene time. This synchronous E-W shortening in the heart of the Isparta Angle, and multidirectional extension in its eastern limb may be explained by relative westward retreat of an eastward dipping subducting Antalya slab that has previously been imaged by seismic tomography and a Benioff zone. The Neogene Bucak thrust west of the Aksu Basin may represent the most recent surface expression of the Antalya subduction zone. (C) 2015 Elsevier B.V. All rights reserved.
A Miocene Onset of the Modern Extensional Regime in the Isparta Angle: Constraints From the Yalva‡ Basin (Southwest Turkey)
(Springer, 2016) Koc, Ayten; Kaymakci, Nuretdin; van Hinsbergen, Douwe J. J.; Vissers, Reinoud L. M.
The pre-Neogene Tauride fold-and-thrust belt, comprising Cretaceous ophiolites and metamorphic rocks and non-metamorphic carbonate thrust slices in southern Turkey, is flanked and overlain by Neogene sedimentary basins. These include poorly studied intra-montane basins including the Yalva double dagger Basin. In this paper, we study the stratigraphy, sedimentology and structure of the Yalva double dagger Basin, which has a Middle Miocene and younger stratigraphy. Our results show that the basin formed as a result of multi-directional extension, with NE-SW to E-W extension dominating over subordinate NW-SE to N-S extension. We show that faults bounding the modern basin also governed basin formation, with proximal facies close to the basin margins grading upwards and basinwards into lacustrine deposits representing the local depocentre. The Yalvac Basin was a local basin, but a similar, contemporaneous history recently reconstructed from the AltA +/- napa Basin, similar to 100 km to the south, shows that multi-directional extension dominated by E-W extension was a regional phenomenon. Extension is still active today, and we conclude that this tectonic regime in the study area has prevailed since Middle Miocene times. Previously documented E-W shortening in the Isparta Angle along the Aksu Thrust, similar to 100 km to the southwest of our study area, is synchronous with the extensional history documented here, and E-W extension to its east shows that Anatolian westwards push is likely not the cause. Synchronous E-W shortening in the heart and E-W extension in the east of the Isparta Angle may be explained by an eastwards-dipping subduction zone previously documented with seismic tomography and earthquake hypocentres. We suggest that this slab surfaces along the Aksu thrust and creates E-W overriding plate extension in the east of the Isparta Angle. Neogene and modern Anatolian geodynamics may thus have been driven by an Aegean, Antalya and Cyprus slab segment that each had their own specific evolution.
Preparing the Ground for Plateau Growth: Late Neogene Central Anatolian Uplift in the Context of Orogenic and Geodynamic Evolution Since the Cretaceous
(Elsevier, 2022) McPhee, Peter J.; Koc, Ayten; van Hinsbergen, Douwe J. J.
Central Anatolia (Turkey) is a small and nascent example of a high orogenic plateau, providing a natural laboratory to study processes driving plateau rise. The 1-km-high plateau interior uplifted since c. 8-5 Ma, with a further phase of kilometre-scale uplift affecting the southern plateau margin since 0.45 Ma. Several causes of plateau rise have been proposed: peeling or dripping delamination of the lithospheric mantle; asthenospheric upwelling through slab gaps created by slab fragmentation or break-off, and; continental underthrusting and crustal shortening below the southern plateau margin. The Neogene history of the plateau has not been diagnostic of the causes of plateau rise. We thus evaluate proposed uplift causes in the context of the Anatolian orogenesis, which formed the plateau lithosphere during subduction since the Cretaceous. We combine this analysis with available constraints on uplift, and geophysical data that illuminate the modern mantle (and crustal) structure. Our analysis suggests that lithospheric dripping, which followed arc magmatism and shortening in the Kirsehir Block (eastern Central Anatolia), is the most likely cause of plateau interior uplift. Lithospheric dripping is, however, an unlikely sole driver of multi-phase uplift along the southern plateau margin. There, underthrusting of the African continental margin, recorded by c. 11-7 Ma thrusting on Cyprus, is a viable cause of uplift since 0.45 Ma, but cannot account for earlier uplift since c. 8-5 Ma. Instead, slab break-off below the southern plateau margin is likely in light of geophysical data. On the SW plateau margin, small-scale peeling delamination of the Central Taurides by the Antalya slab since early Miocene times accounts for >150 km slab retreat with no corresponding upper-plate deformation. A southwest-travelling wave of subsidence and uplift signalled this retreat and may have contributed to coeval oroclinal bending of the western Central Taurides and southeastward thrusting of the Lycian Nappes.
Reply To Comment on "preparing the Ground for Plateau Growth: Late Neogene Central Anatolian Uplift in the Context of Orogenic and Geodynamic Evolution Since the Cretaceous
(Elsevier, 2022) McPhee, Peter J.; van Hinsbergen, Douwe J. J.; Koc, Ayten
Rotations of Normal Fault Blocks Quantify Extension in the Central Tauride Intramontane Basins, Sw Turkey
(Amer Geophysical Union, 2018) Koc, Ayten; van Hinsbergen, Douwe J. J.; Langereis, Cor G.
Quantifying the amount of stretching in extensional basin systems is often challenging in the absence of seismic profiles or boreholes. However, when fault spacing and orientation as well as vertical axis rotation patterns are known, map-view restoration may provide a good estimate of total extension. This integrated structural and paleomagnetic approach provides a relatively straightforward tool in extensional basin restoration and fault zone kinematic analysis. Here we provide results of an extensive paleomagnetic survey of the Neogene Central Tauride intramontane basins (SW Turkey), where previous work revealed a complex array of basin-bounding normal faults and relay ramps. In total, 437 oriented cores were sampled at 43 sites distributed within Miocene-Pliocene continental sedimentary rocks from the Ilgn, Altnapa, Yalvac, and Beyehir basins. Despite the more or less coherent overall strike of the mountain belt and basins, rotations vary from 42 degrees clockwise (Yalvac) to 10 degrees (Beyehir), 21 degrees (Ilgn), and 30 degrees (Altnapa) counterclockwise. We show that the rotation pattern is related to normal faults and lateral variations in fault displacement superimposed on regional rotation patterns. We restore these to estimate a minimum NE-SW horizontal extension of 30-35km across the basin system. As a consequence of our reconstruction, it appears that the Sultandalar range that exposes low-grade metamorphic Paleozoic and Mesozoic rocks of the Geyikda and Bolkarda nappes of the Taurides represents a Miocene extensional core complex. Key Points
Shortening and Extrusion in the East Anatolian Plateau: How Was Neogene Arabia-Eurasia Convergence Tectonically Accommodated
(Elsevier, 2024) van Hinsbergen, Douwe J. J.; Guerer, Derya; Koc, Ayten; Lom, Nalan
Deformation in orogenic belts is typically widely distributed but may be localized to form discrete, fast-moving fault zones enclosing semi-rigid microplates. An example is the Anatolian microplate, which is extruding westwards from the East Anatolian Plateau in the Arabia-Eurasia collision zone along the North and East Anatolian Faults that cause devastating earthquakes, including those of February 6, 2023 in Southeast Anatolia. Here, we summarize the orogenic architecture of the East Anatolian Plateau and its underlying kinematic history since the Cretaceous, and use this to reconstruct the tectonic situation that existed at the onset of and during the development of the Neogene East Anatolian Plateau and the Anatolian microplate. The orogen first formed in the late Cretaceous by subduction-accretion of microcontinental lithosphere below Neotethys oceanic lithosphere. Then, in Paleogene time, the accretionary orogen underwent regional upper plate extension, causing crystalline crust exhumation and deep-marine basin formation. From early Miocene time onwards, the extended orogen shortened again and must have accommodated similar to 350 km of convergence, making crust up to 45 km thick, and causing >2 km of uplift. Since the similar to 13 Ma onset of North Anatolian Fault formation, microplate extrusion absorbed no more than 25 % (similar to 65 km) of Arabia-Eurasia convergence and even during this time alone, >200 km of convergence must have been accommodated by continued similar to N-S shortening. We highlight the need for field studies of the East Anatolian Plateau to identify where and how this major shortening was accommodated, what role it played in plateau rise and the onset and dynamics of microplate extrusion, and to better assess seismic hazards.