@article{BallatoStockliGhassemietal.2013, author = {Ballato, Paolo and Stockli, Daniel F. and Ghassemi, Mohammad R. and Landgraf, Angela and Strecker, Manfred and Hassanzadeh, Jamshid and Friedrich, Anke M. and Tabatabaei, Saeid H.}, title = {Accommodation of transpressional strain in the Arabia-Eurasia collision zone new constraints from (U-Th)/He thermochronology in the Alborz mountains, north Iran}, series = {Tectonics}, volume = {32}, journal = {Tectonics}, number = {1}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1029/2012TC003159}, pages = {1 -- 18}, year = {2013}, abstract = {The Alborz range of N Iran provides key information on the spatiotemporal evolution and characteristics of the Arabia-Eurasia continental collision zone. The southwestern Alborz range constitutes a transpressional duplex, which accommodates oblique shortening between Central Iran and the South Caspian Basin. The duplex comprises NW-striking frontal ramps that are kinematically linked to inherited E-W-striking, right-stepping lateral to obliquely oriented ramps. New zircon and apatite (U-Th)/He data provide a high-resolution framework to unravel the evolution of collisional tectonics in this region. Our data record two pulses of fast cooling associated with SW-directed thrusting across the frontal ramps at similar to 18-14 and 9.5-7.5 Ma, resulting in the tectonic repetition of a fossil zircon partial retention zone and a cooling pattern with a half U-shaped geometry. Uniform cooling ages of similar to 7-6 Ma along the southernmost E-W striking oblique ramp and across its associated NW-striking frontal ramps suggests that the ramp was reactivated as a master throughgoing, N-dipping thrust. We interpret this major change in fault kinematics and deformation style to be related to a change in the shortening direction from NE to N/NNE. The reduction in the obliquity of thrusting may indicate the termination of strike-slip faulting (and possibly thrusting) across the Iranian Plateau, which could have been triggered by an increase in elevation. Furthermore, we suggest that similar to 7-6-m.y.-old S-directed thrusting predated inception of the westward motion of the South Caspian Basin. Citation: Ballato, P., D. F. Stockli, M. R. Ghassemi, A. Landgraf, M. R. Strecker, J. Hassanzadeh, A. Friedrich, and S. H. Tabatabaei (2012), Accommodation of transpressional strain in the Arabia-Eurasia collision zone: new constraints from (U-Th)/He thermochronology in the Alborz mountains.}, language = {en} } @article{LandgrafZielkeArrowsmithetal.2013, author = {Landgraf, Angela and Zielke, Olaf and Arrowsmith, J. Ram{\´o}n and Ballato, Paolo and Strecker, Manfred and Schildgen, Taylor F. and Friedrich, Anke M. and Tabatabaei, Sayyed-Hassan}, title = {Differentiating simple and composite tectonic landscapes using numerical fault slip modeling with an example from the south central Alborz Mountains, Iran}, series = {Journal of geophysical research : Earth surface}, volume = {118}, journal = {Journal of geophysical research : Earth surface}, number = {3}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9003}, doi = {10.1002/jgrf.20109}, pages = {1792 -- 1805}, year = {2013}, abstract = {The tectonically driven growth of mountains reflects the characteristics of the underlying fault systems and the applied tectonic forces. Over time, fault networks might be relatively static, but stress conditions could change and result in variations in fault slip orientation. Such a tectonic landscape would transition from a simple to a composite state: the topography of simple landscapes is correlated with a single set of tectonic boundary conditions, while composite landscapes contain inherited topography due to earlier deformation under different boundary conditions. We use fault interaction modeling to compare vertical displacement fields with topographic metrics to differentiate the two types of landscapes. By successively rotating the axis of maximum horizontal stress, we produce a suite of vertical displacement fields for comparison with real landscapes. We apply this model to a transpressional duplex in the south central Alborz Mountains of Iran, where NW oriented compression was superseded by neotectonic NE compression. The consistency between the modeled displacement field and real landforms indicates that the duplex topography is mostly compatible with the modern boundary conditions, but might include a small remnant from the earlier deformation phase. Our approach is applicable for various tectonic settings and represents an approach to identify the changing boundary conditions that produce composite landscapes. It may be particularly useful for identifying changes that occurred in regions where river profiles may no longer record a signal of the change or where the spatial pattern of uplift is complex.}, language = {en} } @article{YildirimMelnickBallatoetal.2013, author = {Yildirim, Cengiz and Melnick, Daniel and Ballato, Paolo and Schildgen, Taylor F. and Echtler, Helmut Peter and Erginal, A. Evren and Kiyak, Nafiye Gunec and Strecker, Manfred}, title = {Differential uplift along the northern margin of the Central Anatolian Plateau - inferences from marine terraces}, series = {Quaternary science reviews : the international multidisciplinary research and review journal}, volume = {81}, journal = {Quaternary science reviews : the international multidisciplinary research and review journal}, number = {4}, publisher = {Elsevier}, address = {Oxford}, issn = {0277-3791}, doi = {10.1016/j.quascirev.2013.09.011}, pages = {12 -- 28}, year = {2013}, abstract = {Emerged marine terraces and paleoshorelines along plate margins are prominent geomorphic markers that can be used to quantify the rates and patterns of crustal deformation. The northern margin of the Central Anatolian Plateau has been interpreted as an actively deforming orogenic wedge between the North Anatolian Fault and the Black Sea. Here we use uplifted marine terraces across principal faults on the Sinop Peninsula at the central northern side of the Pontide orogenic wedge to unravel patterns of Quaternary faulting and orogenic wedge behavior. We leveled the present-day elevations of paleoshorelines and dated marine terrace deposits using optically stimulated luminescence (OSL) to determine coastal uplift. The elevations of the paleoshorelines vary between 4 +/- 0.2 and 67 +/- 1.4 m above sea level and OSL ages suggest terrace formation episodes during interglacial periods at ca 125, 190, 400 and 570 ka, corresponding to marine isotopic stages (MIS) 5e, 7a, 11 and 15. Mean apparent vertical displacement rates (without eustatic correction) deduced from these terraces range between 0.02 and 0.18 mm/a, with intermittent faster rates of up to 0.26 mm/a. We obtained higher rates at the eastern and southern parts of the peninsula, toward the hinterland, indicating non-uniform uplift across the different morphotectonic segments of the peninsula. Our data are consistent with active on- and offshore faulting across the Sinop Peninsula. When integrated with regional tectonic observations, the faulting pattern reflects shortening distributed over a broad region of the northern margin of the Central Anatolian Plateau during the Quaternary.}, language = {en} }