TY  - JOUR
A1  - Georgieva, Viktoria
A1  - Gallagher, Kerry
A1  - Sobczyk, Artur
A1  - Sobel, Edward
A1  - Schildgen, Taylor F.
A1  - Ehlers, Todd
A1  - Strecker, Manfred
T1  - Effects of slab-window, alkaline volcanism, and glaciation on thermochronometer cooling histories, Patagonian Andes
JF  - Earth & planetary science letters
N2  - Southern Patagonia is a prime example of ongoing oceanic ridge collision and slab-window formation sustained over several million years. The impact of these phenomena on the thermal structure and exhumation of the crust have been mainly assessed with low-temperature thermochronology of bedrock samples. Here, we infer thermal histories from new and existing thermochronological data from the region of most recent ridge collision. In particular, we evaluate the potential far-reaching thermal effects of the evolving slab window, which have previously been considered responsible for patterns of late Miocene reheating associated with back-arc alkaline volcanism. Our model results define protracted cooling since similar to 15 Ma and stepwise exhumation since the late Miocene. The pattern of stepwise exhumation closely matches the onset of Patagonian glaciation at 7 Ma and the successive pulse of glacial incision coeval with neotectonic activity since 3-4 Ma that are also documented by independent geological and geomorphological evidence in the region. Importantly, our findings challenge the recently suggested lack of glacial erosion and incision since 5 Ma in this region. Furthermore, in contrast to previous modelling studies, we find that the available data do not evidence a previously proposed northward-propagating heating event associated with alkaline volcanism. We hypothesize that the anomalous alkaline volcanism in the Patagonian back-arc might be related to trench-orthogonal tears aligned with transform faults in the subducting plate. The substantial differences from the previous modelling procedure on some of the same samples is demonstrated to result from an important lack of convergence in model runs. (C) 2019 Elsevier B.V. All rights reserved.
KW  - inverse thermal modelling
KW  - thermochronology
KW  - apatite (U-Th)/He
KW  - apatite fission track
KW  - Patagonian Andes
KW  - slab window
Y1  - 2019
U6  - https://doi.org/10.1016/j.epsl.2019.01.030
SN  - 0012-821X
SN  - 1385-013X
VL  - 511
SP  - 164
EP  - 176
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Pingel, Heiko
A1  - Schildgen, Taylor F.
A1  - Strecker, Manfred
A1  - Wittmann, Hella
T1  - Pliocene-Pleistocene orographic control on denudation in northwest Argentina
JF  - Geology
N2  - The intermontane Humahuaca Basin in the Eastern Cordillera of the northwest Argentine Andes lies leeward of an orographic barrier to easterly derived moisture. An average of >2000 mm/yr of rainfall along the eastern flanks of the barrier contrasts with <200 mm/yr in the orogen interior. Paleoenvironmental reconstructions suggest that the basin became disconnected from the foreland during the Miocene-Pliocene by the growth of fault-bounded mountain ranges. Fossil records, sedimentology, and stable isotope data imply that rerouting of the fluvial network by 4.2 Ma and reduced rainfall by ca. 3 Ma were consequences of that range uplift. Here, we present cosmogenic nuclide-derived (Be-10) paleodenudation rates from 6 to 2 Ma fluvial deposits collected from the Humahuaca Basin. Despite increased tectonic activity, our Be-10 data show a tenfold decrease in denudation rates at ca. 3 Ma, documenting a link between uplift-induced semiarid conditions and decreasing hillslope denudation rates. This new data set thus demonstrates the influence of hydrological change on spatiotemporal denudation patterns in tectonically active mountain areas.
Y1  - 2019
U6  - https://doi.org/10.1130/G45800.1
SN  - 0091-7613
SN  - 1943-2682
VL  - 47
IS  - 4
SP  - 359
EP  - 362
PB  - American Institute of Physics
CY  - Boulder
ER  - 
TY  - JOUR
A1  - Ballato, Paolo
A1  - Parra, Mauricio
A1  - Schildgen, Taylor F.
A1  - Dunkl, I.
A1  - Yildirim, C.
A1  - Özsayin, Erman
A1  - Sobel, Edward
A1  - Echtler, H.
A1  - Strecker, Manfred
T1  - Multiple exhumation phases in the Central Pontides (N Turkey)
BT  - new temporal constraints on Major geodynamic changes associated with the closure of the Neo-Tethys Ocean
JF  - Tectonics
N2  - The Central Pontides of N Turkey represents a mobile orogenic belt of the southern Eurasian margin that experienced several phases of exhumation associated with the consumption of different branches of the Neo-Tethys Ocean and the amalgamation of continental domains. Our new low-temperature thermochronology data help to constrain the timing of these episodes, providing new insights into associated geodynamic processes. In particular, our data suggest that exhumation occurred at (1) similar to 110 to 90Ma, most likely during tectonic accretion and exhumation of metamorphic rocks from the subduction zone; (2) from similar to 60 to 40Ma, during the collision of the Kirehir and Anatolide-Tauride microcontinental domains with the Eurasian margin; (3) from similar to 0 to 25Ma, either during the early stages of the Arabia-Eurasia collision (soft collision) when the Arabian passive margin reached the trench, implying 70 to 530km of subduction of the Arabian passive margin, or during a phase of trench advance predating hard collision at similar to 20Ma; and (4) similar to 11Ma to the present, during transpression associated with the westward motion of Anatolia. Our findings document the punctuated nature of fault-related exhumation, with episodes of fast cooling followed by periods of slow cooling or subsidence, the role of inverted normal faults in controlling the Paleogene exhumation pattern, and of the North Anatolian Fault in dictating the most recent pattern of exhumation.
KW  - thermal modeling
KW  - Central Pontides
KW  - Arabia-Eurasia collision
KW  - trench advance
KW  - Anatolia westward motion
KW  - inversion tectonics
Y1  - 2018
U6  - https://doi.org/10.1029/2017TC004808
SN  - 0278-7407
SN  - 1944-9194
VL  - 37
IS  - 6
SP  - 1831
EP  - 1857
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Tofelde, Stefanie
A1  - Duesing, Walter
A1  - Schildgen, Taylor F.
A1  - Wickert, Andrew D.
A1  - Wittmann, Hella
A1  - Alonso, Ricardo N.
A1  - Strecker, Manfred
T1  - Effects of deep-seated versus shallow hillslope processes on cosmogenic Be-10 concentrations in fluvial sand and gravel
JF  - Earth surface processes and landforms : the journal of the British Geomorphological Research Group
N2  - Terrestrial cosmogenic nuclide (TCN) concentrations in fluvial sediment, from which denudation rates are commonly inferred, can be affected by hillslope processes. TCN concentrations in gravel and sand may differ if localized, deep-excavation processes (e.g. landslides, debris flows) affect the contributing catchment, whereas the TCN concentrations of sand and gravel tend to be more similar when diffusional processes like soil creep and sheetwash are dominant. To date, however, no study has systematically compared TCN concentrations in different detrital grain-size fractions with a detailed inventory of hillslope processes from the entire catchment. Here we compare concentrations of the TCN Be-10 in 20 detrital sand samples from the Quebrada del Toro (southern Central Andes, Argentina) to a hillslope-process inventory from each contributing catchment. Our comparison reveals a shift from low-slope gullying and scree production in slowly denuding, low-slope areas to steep-slope gullying and landsliding in fast-denuding, steep areas. To investigate whether the nature of hillslope processes (locally excavating or more uniformly denuding) may be reflected in a comparison of the Be-10 concentrations of sand and gravel, we define the normalized sand-gravel index (NSGI) as the Be-10-concentration difference between sand and gravel divided by their summed concentrations. We find a positive, linear relationship between the NSGI and median slope, such that our NSGI values broadly reflect the shift in hillslope processes from low-slope gullying and scree production to steep-slope gullying and landsliding. Higher NSGI values characterize regions affected by steep-slope gullying or landsliding. We relate the large scatter in the relationship, which is exhibited particularly in low-slope areas, to reduced hillslope-channel connectivity and associated transient sediment storage within those catchments. While high NSGI values in well-connected catchments are a reliable signal of deep-excavation processes, hillslope excavation processes may not be reliably recorded by NSGI values where sediment experiences transient storage. (c) 2018 John Wiley & Sons, Ltd.
Y1  - 2018
U6  - https://doi.org/10.1002/esp.4471
SN  - 0197-9337
SN  - 1096-9837
VL  - 43
IS  - 15
SP  - 3086
EP  - 3098
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Guzman, Silvina
A1  - Strecker, Manfred
A1  - Marti, Joan
A1  - Petrinovic, Ivan A.
A1  - Schildgen, Taylor F.
A1  - Grosse, Pablo
A1  - Montero-Lopez, Carolina
A1  - Neri, Marco
A1  - Carniel, Roberto
A1  - D. Hongn, Fernando
A1  - Muruaga, Claudia
A1  - Sudo, Masafumi
T1  - Construction and degradation of a broad volcanic massif: The Vicuna Pampa volcanic complex, southern Central Andes, NW Argentina
JF  - Geological Society of America bulletin
N2  - The Vicuna Pampa volcanic complex, at the SE edge of the arid Puna Plateau of the Central Andes, records the interplay between volcanic construction and degra-dational processes. The low-sloping Vicuna Pampa volcanic complex, with a 1200-m-deep, southeastward-opening depression, was previously interpreted as a collapse caldera based on morphological considerations. However, characteristic features associated with collapse calderas do not exist, and close inspection instead suggests that the Vicuna Pampa volcanic complex is a strongly eroded, broad, massif-type composite volcano of mainly basaltic to trachyandesitic composition. Construction of the Vicuna Pampa volcanic complex occurred during two distinct cycles separated by the development of the depression. The first and main cycle took place at ca. 12 Ma and was dominated by lava flows and subordinate scoria cones and domes. The second cycle, possibly late Miocene in age, affected the SW portion of the depression with the emplacement of domes. We interpret the central depression as the result of a possible sector collapse and subsequent intense fluvial erosion during middle to late Miocene time, facilitated by faulting, steepened topography, and wetter climate conditions compared to today. We estimate that similar to 65% of the initial edifice of similar to 240 km(3) was degraded. The efficiency of degradation processes for removing mass from the Vicuna Pampa volcanic complex is surprising, considering that today the region is arid, and the stream channels within the complex are predominantly transport limited, forming a series of coalesced, aggraded alluvial fans and eolian infill. Hence, the Vicuna Pampa volcanic complex records the effects of past degradation efficiency that differs substantially from that of today.
Y1  - 2017
U6  - https://doi.org/10.1130/B31631.1
SN  - 0016-7606
SN  - 1943-2674
VL  - 129
SP  - 750
EP  - 766
PB  - American Institute of Physics
CY  - Boulder
ER  - 
TY  - JOUR
A1  - Garcin, Yannick
A1  - Schildgen, Taylor F.
A1  - Acosta, Veronica Torres
A1  - Melnick, Daniel
A1  - Guillemoteau, Julien
A1  - Willenbring, Jane
A1  - Strecker, Manfred
T1  - Short-lived increase in erosion during the African Humid Period
BT  - evidence from the northern Kenya Rift
JF  - Earth & planetary science letters
N2  - The African Humid Period (AHP) between similar to 15 and 5.5 cal. kyr BP caused major environmental change in East Africa, including filling of the Suguta Valley in the northern Kenya Rift with an extensive (similar to 2150 km(2)), deep (similar to 300 m) lake. Interfingering fluvio-lacustrine deposits of the Baragoi paleo-delta provide insights into the lake-level history and how erosion rates changed during this time, as revealed by delta-volume estimates and the concentration of cosmogenic Be-10 in fluvial sand. Erosion rates derived from delta-volume estimates range from 0.019 to 0.03 mm yr(-1). Be-10-derived paleo-erosion rates at similar to 11.8 cal. kyr BP ranged from 0.035 to 0.086 mm yr(-1), and were 2.7 to 6.6 times faster than at present. In contrast, at similar to 8.7 cal. kyr BP, erosion rates were only 1.8 times faster than at present. Because Be-10-derived erosion rates integrate over several millennia; we modeled the erosion-rate history that best explains the 10Be data using established non-linear equations that describe in situ cosmogenic isotope production and decay. Two models with different temporal constraints (15-6.7 and 12-6.7 kyr) suggest erosion rates that were 25 to 300 times higher than the initial erosion rate (pre-delta formation). That pulse of high erosion rates was short (similar to 4 kyr or less) and must have been followed by a rapid decrease in rates while climate remained humid to reach the modern Be-10-based erosion rate of,similar to 0.013 mm yr(-1). Our simulations also flag the two highest Be-10-derived erosion rates at 11.8 kyr BP related to nonuniform catchment erosion. These changes in erosion rates and processes during the AHP may reflect a strong increase in precipitation, runoff, and erosivity at the arid-to-humid transition either at 15 or similar to 12 cal. kyr BP, before the landscape stabilized again, possibly due to increased soil production and denser vegetation.
KW  - northern Kenya Rift
KW  - Baragoi
KW  - paleo-delta
KW  - African Humid Period
KW  - erosion
KW  - Be-10
Y1  - 2017
U6  - https://doi.org/10.1016/j.epsl.2016.11.017
SN  - 0012-821X
SN  - 1385-013X
VL  - 459
SP  - 58
EP  - 69
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Tofelde, Stefanie
A1  - Schildgen, Taylor F.
A1  - Savi, Sara
A1  - Pingel, Heiko
A1  - Wickert, Andrew D.
A1  - Bookhagen, Bodo
A1  - Wittmann, Hella
A1  - Alonso, Ricardo N.
A1  - Cottle, John
A1  - Strecker, Manfred
T1  - 100 kyr fluvial cut-and-fill terrace cycles since the Middle Pleistocene in the southern Central Andes, NW Argentina
JF  - Earth & planetary science letters
N2  - Fluvial fill terraces in intermontane basins are valuable geomorphic archives that can record tectonically and/or climatically driven changes of the Earth-surface process system. However, often the preservation of fill terrace sequences is incomplete and/or they may form far away from their source areas, complicating the identification of causal links between forcing mechanisms and landscape response, especially over multi-millennial timescales. The intermontane Toro Basin in the southern Central Andes exhibits at least five generations of fluvial terraces that have been sculpted into several-hundred-meter-thick Quaternary valley-fill conglomerates. New surface-exposure dating using nine cosmogenic Be-10 depth profiles reveals the successive abandonment of these terraces with a 100 kyr cyclicity between 75 +/- 7 and 487 +/- 34 ka. Depositional ages of the conglomerates, determined by four Al-26/Be-10 burial samples and U-Pb zircon ages of three intercalated volcanic ash beds, range from 18 +/- 141 to 936 +/- 170 ka, indicating that there were multiple cut-and-fill episodes. Although the initial onset of aggradation at similar to 1 Ma and the overall net incision since ca. 500 ka can be linked to tectonic processes at the narrow basin outlet, the superimposed 100 kyr cycles of aggradation and incision are best explained by eccentricity-driven climate change. Within these cycles, the onset of river incision can be correlated with global cold periods and enhanced humid phases recorded in paleoclimate archives on the adjacent Bolivian Altiplano, whereas deposition occurred mainly during more arid phases on the Altiplano and global interglacial periods. We suggest that enhanced runoff during global cold phases - due to increased regional precipitation rates, reduced evapotranspiration, or both - resulted in an increased sediment-transport capacity in the Toro Basin, which outweighed any possible increases in upstream sediment supply and thus triggered incision. Compared with two nearby basins that record precessional (21-kyr) and long-eccentricity (400-kyr) forcing within sedimentary and geomorphic archives, the recorded cyclicity scales with the square of the drainage basin length. (C) 2017 Elsevier B.V. All rights reserved.
KW  - Be-10 depth-profiles
KW  - surface inflation
KW  - aggradation-incision cycles
KW  - glacial-interglacial cycles
KW  - landscape response to climate change
KW  - Eastern Cordillera
Y1  - 2017
U6  - https://doi.org/10.1016/j.epsl.2017.06.001
SN  - 0012-821X
SN  - 1385-013X
VL  - 473
SP  - 141
EP  - 153
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Georgieva, Viktoria
A1  - Melnick, Daniel
A1  - Schildgen, Taylor F.
A1  - Ehlers, Todd
A1  - Lagabrielle, Yves
A1  - Enkelmann, Eva
A1  - Strecker, Manfred
T1  - Tectonic control on rock uplift, exhumation, and topography above an oceanic ridge collision: Southern Patagonian Andes (47 degrees S), Chile
JF  - Tectonics
N2  - The subduction of bathymetric anomalies at convergent margins can profoundly affect subduction dynamics, magmatism, and the structural and geomorphic evolution of the overriding plate. The Northern Patagonian Icefield (NPI) is located east of the Chile Triple Junction at similar to 47 degrees S, where the Chile Rise spreading center collides with South America. This region is characterized by an abrupt increase in summit elevations and relief that has been controversially debated in the context of geodynamic versus glacial erosion effects on topography. Here we present geomorphic, thermochronological, and structural data that document neotectonic activity along hitherto unrecognized faults along the flanks of the NPI. New apatite (U-Th)/He bedrock cooling ages suggest faulting since 2-3 Ma. We infer the northward translation of an similar to 140 km long fore-arc sliver-the NPI block-results from enhanced partitioning of oblique plate convergence due to the closely spaced collision of three successive segments of the Chile Rise. In this model, greater uplift occurs in the hanging wall of the Exploradores thrust at the northern leading edge of the NPI block, whereas the Cachet and Liquine-Ofqui dextral faults decouple the NPI block along its eastern and western flanks, respectively. Localized extension possibly occurs at its southern trailing edge along normal faults associated with margin-parallel extension, tectonic subsidence, and lower elevations along the Andean crest line. Our neotectonic model provides a novel explanation for the abrupt topographic variations inland of the Chile Triple Junction and emphasizes the fundamental effects of local tectonics on exhumation and topographic patterns in this glaciated landscape.
Y1  - 2016
U6  - https://doi.org/10.1002/2016TC004120
SN  - 0278-7407
SN  - 1944-9194
VL  - 35
SP  - 1317
EP  - 1341
PB  - American Geophysical Union
CY  - Washington
ER  - 
TY  - JOUR
A1  - Radaeff, Giuditta
A1  - Cosentino, Domenico
A1  - Cipollari, Paola
A1  - Schildgen, Taylor F.
A1  - Iadanza, Annalisa
A1  - Strecker, Manfred
A1  - Darbas, Guldemin
A1  - Gürbüz, Kemal
T1  - Stratigraphic architecture of the upper Messinian deposits of the Adana Basin (southern Turkey): implications for the Messinian Salinity Crisis and the Taurus petroleum system
JF  - Italian journal of geosciences : bollettino della Società Geologica Italiana e del Servizio Geologico d'Italia
N2  - This paper is mainly based on field work carried out on the Messinian deposits of the Adana Basin ( southern Turkey), as well as on the interpretation of seismic reflection profiles to understand 3D geometries of the basin fill. Chronostratigraphic constraints for the Messinian deposits are from micropaleontological studies on foraminifera, ostracods, and calcareous nannofossils, recently carried out on the Messinian deposits of the Adana Basin. Our results indicate that this basin developed in a marginal area strictly related to the Mediterranean realm. The Messinian deposits of the Adana Basin record all the main steps of the Messinian Salinity Crisis ( MSC) that affected the Mediterranean area at the end of the Miocene. The new stratigraphic model for the Messinian deposits of the Adana Basin provided in this work gives new insights into both the MSC and the Taurus petroleum system. Despite their complete correspondence with the MSC, the Messinian deposits of the Adana Basin show some differences with respect to the current conceptual model for the MSC. For example, in the current conceptual model for the MSC, only one regional erosional surface ( MES) characterizes the MSC deposits. In the Adana Basin, two regional erosional surfaces, named MES1 and MES2, separate the Messinian deposits related to the MSC in Lower Evaporites, Resedimented Lower Evaporites ( RLE), and upper Messinian continental deposits containing a late Lago-Mare ostracod assemblage ( mainly fluvial coarse-grained and fine-grained sediments). In some places, Brecciated Limestones lie just above the MES1 and beneath the RLE. In addition, the RLE are thought to be related to the same step that brought to the Messinian halite deposition throughout the Mediterranean, pointing to a hyperhaline environment. In contrast, the fine-grained deposits of the RLE of the Adana Basin show the occurrence of Parathetyan brackish ostracod fauna ( early Lago-Mare ostracod assemblages), which defines an oligohaline depositional environment for the RLE. In terms of hydrocarbon prospecting, the Messinian evaporites of the Adana Basin have been considered as a perfect seal for the active Taurus petroleum system. Our results show that due to the complex stratigraphic architecture of the basin fill and the occurrence of two regional erosional surfaces ( MES1 and MES2), the Messinian evaporites are discontinuously present both in surface and in the subsurface of the Adana Basin. However, seal properties in the Adana Basin could be found in the Lower Pliocene deep marine clays of the Avadan Formation. This work leads to suggest a new stratigraphical model for the Messinian deposits of the Adana Basin, allowing us to amend the classical scheme with respect to the Messinian, and to officially define some new formations within the stratigraphy of the Adana Basin.
KW  - eastern Mediterranean
KW  - Adana Basin
KW  - Messinian Salinity Crisis
KW  - physical stratigraphy
KW  - Messinian Erosional Surface
KW  - Taurus petroleum system
Y1  - 2016
U6  - https://doi.org/10.3301/IJG.2015.18
SN  - 2038-1719
SN  - 2038-1727
VL  - 135
SP  - 408
EP  - 424
PB  - Società Geologica Italiana
CY  - Roma
ER  - 
TY  - JOUR
A1  - Dey, Saptarshi
A1  - Thiede, Rasmus Christoph
A1  - Schildgen, Taylor F.
A1  - Wittmann, Hella
A1  - Bookhagen, Bodo
A1  - Scherler, Dirk
A1  - Jain, Vikrant
A1  - Strecker, Manfred
T1  - Climate-driven sediment aggradation and incision since the late Pleistocene in the NW Himalaya, India
JF  - Earth & planetary science letters
N2  - Deciphering the response of sediment routing systems to climatic forcing is fundamental for understanding the impacts of climate change on landscape evolution. In the Kangra Basin (northwest Sub-Himalaya, India), upper Pleistocene to Holocene alluvial fills and fluvial terraces record periodic fluctuations of sediment supply and transport capacity on timescales of 10(3) to 10(5) yr. To evaluate the potential influence of climate change on these fluctuations, we compare the timing of aggradation and incision phases recorded within remnant alluvial fans and terraces with climate archives. New surface-exposure dating of six terrace levels with in-situ cosmogenic Be-10 indicates the onset of incision phases. Two terrace surfaces from the highest level (T1) sculpted into the oldest preserved alluvial fan (AF1) date back to 53.4 +/- 3.2 ka and 43.0 +/- 2.7 ka (1 sigma). T2 surfaces sculpted into the remnants of AF1 have exposure ages of 18.6 +/- 1.2 ka and 15.3 +/- 0.9 ka, while terraces sculpted into the upper Pleistocene-Holocene fan (AF2) provide ages of 9.3 +/- 0.4 ka (T3), 7.1 +/- 0.4 ka (T4), 5.2 +/- 0.4 ka (T5) and 3.6 +/- 0.2 ka (T6). Together with previously published OSL ages yielding the timing of aggradation, we find a correlation between variations in sediment transport with oxygen-isotope records from regions affected by the Indian Summer Monsoon. During periods of increased monsoon intensity and post-Last Glacial Maximum glacial retreat, aggradation occurred in the Kangra Basin, likely due to high sediment flux, whereas periods of weakened monsoon intensity or lower sediment supply coincide with incision. (C) 2016 Elsevier B.V. All rights reserved.
KW  - alluvial-fan sedimentation
KW  - terrestrial cosmogenic nuclides
KW  - Indian Summer Monsoon
KW  - Last Glacial Maximum
KW  - paleo-erosion rate
Y1  - 2016
U6  - https://doi.org/10.1016/j.epsl.2016.05.050
SN  - 0012-821X
SN  - 1385-013X
VL  - 449
SP  - 321
EP  - 331
PB  - Elsevier
CY  - Amsterdam
ER  -