TY - JOUR A1 - Bookhagen, Bodo A1 - Echtler, Helmut Peter A1 - Melnick, Daniel A1 - Strecker, Manfred A1 - Spencer, Joel Q. G. T1 - Using uplifted Holocene beach berms for paleoseismic analysis on the Santa Maria Island, south-central Chile N2 - Major earthquakes ( M > 8) have repeatedly ruptured the Nazca-South America plate interface of south-central Chile involving meter scale land-level changes. Earthquake recurrence intervals, however, extending beyond limited historical records are virtually unknown, but would provide crucial data on the tectonic behavior of forearcs. We analyzed the spatiotemporal pattern of Holocene earthquakes on Santa Maria Island (SMI; 37 degrees S), located 20 km off the Chilean coast and approximately 70 km east of the trench. SMI hosts a minimum of 21 uplifted beach berms, of which a subset were dated to calculate a mean uplift rate of 2.3 +/- 0.2 m/ky and a tilting rate of 0.022 +/- 0.002 degrees/ky. The inferred recurrence interval of strandline-forming earthquakes is similar to 180 years. Combining coseismic uplift and aseismic subsidence during an earthquake cycle, the net gain in strandline elevation in this environment is similar to 0.4 m per event Y1 - 2006 UR - http://www.agu.org/journals/gl/ U6 - https://doi.org/10.1029/2006gl026734 SN - 0094-8276 ER - TY - JOUR A1 - Yildirim, Cengiz A1 - Schildgen, Taylor F. A1 - Echtler, Helmut Peter A1 - Melnick, Daniel A1 - Strecker, Manfred T1 - Late Neogene and active orogenic uplift in the Central Pontides associated with the North Anatolian Fault implications for the northern margin of the Central Anatolian Plateau, Turkey JF - Tectonics N2 - Surface uplift at the northern margin of the Central Anatolian Plateau (CAP) is integrally tied to the evolution of the Central Pontides (CP), between the North Anatolian Fault (NAF) and the Black Sea. Our regional morphometric and plate kinematic analyses reveal topographic anomalies, steep channel gradients, and local high relief areas as indicators of ongoing differential surface uplift, which is higher in the western CP compared to the eastern CP and fault-normal components of geodetic slip vectors and the character of tectonic activity of the NAF suggest that stress is accumulated in its broad restraining bend. Seismic reflection and structural field data show evidence for a deep structural detachment horizon responsible for the formation of an actively northward growing orogenic wedge with a positive flower-structure geometry across the CP and the NAF. Taken together, the tectonic, plate kinematic, and geomorphic observations imply that the NAF is the main driving mechanism for wedge tectonics and uplift in the CP. In addition, the NAF Zone defines the boundary between the extensional CAP and the contractional CP. The syntectonic deposits within inverted intermontane basins and deeply incised gorges suggest that the formation of relief, changes in sedimentary dynamics, and > 1 km fluvial incision resulted from accelerated uplift starting in the early Pliocene. The Central Pontides thus provide an example of an accretionary wedge with surface-breaking faults that play a critical role in mountain building processes, sedimentary basin development, and ensuing lateral growth of a continental plateau since the end of the Miocene. Y1 - 2011 U6 - https://doi.org/10.1029/2010TC002756 SN - 0278-7407 VL - 30 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Yildirim, Cengiz A1 - Melnick, Daniel A1 - Ballato, Paolo A1 - Schildgen, Taylor F. A1 - Echtler, Helmut Peter A1 - Erginal, A. Evren A1 - Kiyak, Nafiye Gunec A1 - Strecker, Manfred T1 - Differential uplift along the northern margin of the Central Anatolian Plateau - inferences from marine terraces JF - Quaternary science reviews : the international multidisciplinary research and review journal N2 - 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. KW - Orogenic Plateaus KW - Central Anatolian Plateau KW - Plateau margins KW - Central Pontides KW - Orogenic wedges KW - Black Sea KW - Marine terraces KW - Uplift rate Y1 - 2013 U6 - https://doi.org/10.1016/j.quascirev.2013.09.011 SN - 0277-3791 VL - 81 IS - 4 SP - 12 EP - 28 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Yildirim, Cengiz A1 - Schildgen, Taylor F. A1 - Echtler, Helmut Peter A1 - Melnick, Daniel A1 - Bookhagen, Bodo A1 - Ciner, T. Attila A1 - Niedermann, Samuel A1 - Merchel, Silke A1 - Martschini, Martin A1 - Steier, Peter A1 - Strecker, Manfred T1 - Tectonic implications of fluvial incision and pediment deformation at the northern margin of the Central Anatolian Plateau based on multiple cosmogenic nuclides JF - Tectonics N2 - We document Quaternary fluvial incision driven by fault-controlled surface deformation in the inverted intermontane Gökirmak Basin in the Central Pontide mountains along the northern margin of the Central Anatolian Plateau. In-situ-produced Be-10, Ne-21, and Cl-36 concentrations from gravel-covered fluvial terraces and pediment surfaces along the trunk stream of the basin (the Gökirmak River) yield model exposure ages ranging from 71ka to 34645ka and average fluvial incision rates over the past similar to 350ka of 0.280.01mm a(-1). Similarities between river incision rates and coastal uplift rates at the Black Sea coast suggest that regional uplift is responsible for the river incision. Model exposure ages of deformed pediment surfaces along tributaries of the trunk stream range from 605ka to 110 +/- 10ka, demonstrating that the thrust faults responsible for pediment deformation were active after those times and were likely active earlier as well as explaining the topographic relief of the region. Together, our data demonstrate cumulative incision that is linked to active internal shortening and uplift of similar to 0.3mm a(-1) in the Central Pontide orogenic wedge, which may ultimately contribute to the lateral growth of the northern Anatolian Plateau. KW - Tectonic Geomorphology KW - Fluvial Incision KW - Surface Exposure Age KW - Uplift Rate Y1 - 2013 U6 - https://doi.org/10.1002/tect.20066 SN - 0278-7407 SN - 1944-9194 VL - 32 IS - 5 SP - 1107 EP - 1120 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Melnick, Daniel A1 - Bookhagen, Bodo A1 - Strecker, Manfred A1 - Echtler, Helmut Peter T1 - Segmentation of megathrust rupture zones from fore-arc deformation patterns over hundreds to millions of years, Arauco peninsula, Chile N2 - This work explores the control of fore-arc structure on segmentation of megathrust earthquake ruptures using coastal geomorphic markers. The Arauco-Nahuelbuta region at the south-central Chile margin constitutes an anomalous fore- arc sector in terms of topography, geology, and exhumation, located within the overlap between the Concepcion and Valdivia megathrust segments. This boundary, however, is only based on similar to 500 years of historical records. We integrate deformed marine terraces dated by cosmogenic nuclides, syntectonic sediments, published fission track data, seismic reflection profiles, and microseismicity to analyze this earthquake boundary over 10(2) -10(6) years. Rapid exhumation of Nahuelbuta's dome-like core started at 4 +/- 1.2 Ma, coeval with inversion of the adjacent Arauco basin resulting in emergence of the Arauco peninsula. Here, similarities between topography, spatiotemporal trends in fission track ages, Pliocene-Pleistocene growth strata, and folded marine terraces suggest that margin-parallel shortening has dominated since Pliocene time. This shortening likely results from translation of a fore-arc sliver or microplate, decoupled from South America by an intra-arc strike-slip fault. Microplate collision against a buttress leads to localized uplift at Arauco accrued by deep-seated reverse faults, as well as incipient oroclinal bending. The extent of the Valdivia segment, which ruptured last in 1960 with an M-w 9.5 event, equals the inferred microplate. We propose that mechanical homogeneity of the fore-arc microplate delimits the Valdivia segment and that a marked discontinuity in the continental basement at Arauco acts as an inhomogeneous barrier controlling nucleation and propagation of 1960-type ruptures. As microplate-related deformation occurs since the Pliocene, we propose that this earthquake boundary and the extent of the Valdivia segment are spatially stable seismotectonic features at million year scale. Y1 - 2009 UR - http://www.agu.org/journals/jb/ U6 - https://doi.org/10.1029/2008jb005788 SN - 0148-0227 ER -