@article{BlisniukHackerGlodnyetal.2001, author = {Blisniuk, Peter Michael and Hacker, Bradley R. and Glodny, Johannes and Ratschbacher, Lothar and Bi, Siwen and Wu, Zhenhan and McWilliams, Michael O. and Calvert, Andy}, title = {Normal faulting in central Tibet since at least 13.5 Myr}, year = {2001}, language = {en} } @article{BachmannOnckenGlodnyetal.2009, author = {Bachmann, Raik and Oncken, Onno and Glodny, Johannes and Seifert, Wolfgang and Georgieva, Viktoria and Sudo, Masafumi}, title = {Exposed plate interface in the European Alps reveals fabric styles and gradients related to an ancient seismogenic coupling zone}, issn = {0148-0227}, doi = {10.1029/2008jb005927}, year = {2009}, abstract = {We present observations from a continuous exposure of an ancient plate interface in the depth range of its former seismogenic zone in the central Alps of Europe related to Late Cretaceous-early Tertiary subduction and accretion of the South Penninic lower plate underneath the Adriatic upper plate. The material forming the exposed plate interface zone has experienced flow and fracturing over an extended period of time followed by syncollisional exhumation, thus reflecting a multistage evolution. Fabric formation and metamorphism, however, chiefly record the deformation conditions of the precollisional setting along the plate interface. We identify an unstable slip domain from pseudotachylytes occurring in the temperature range between 200 and 300 degrees C. This zone coincides with a domain of intense veining in the subduction melange with mineral growth into open cavities, indicating fast, possibly seismic, rupture. Evidence for transient near-lithostatic fluid pressure as well as brittle fractures competing with mylonitic shear zones continues into the region below the occurrence of pseudotachylytes, possibly reflecting a zone of conditionally stable slip. The zone above the unstable slip area is devoid of veins but displays ample evidence of fluid-assisted processes similar to the deeper zone: solution-precipitation creep and dehydration reactions in the melange matrix, hydration, and sealing of the base of the upper plate. Seismic rupture here is possibly expressed by ubiquitous localized deformation zones. We hypothesize that trenchward sealing of parts of the plate interface as well as reaction-enhanced destruction of upper plate permeability is an important component, localizing the unstable slip zone. This relation may result from the competition of the pervasive, presumably interseismic, pressure solution creep destroying permeability and building elevated fluid pressure until the strength threshold is reached with seismic failure.}, language = {en} } @article{WillnerBarrGlodnyetal.2015, author = {Willner, Arne P. and Barr, Sandra M. and Glodny, Johannes and Massonne, Hans-Joachim and Sudo, Masafumi and Thomson, Stuart N. and Van Staal, Cees R. and White, Chris E.}, title = {Effects of fluid flow, cooling and deformation as recorded by Ar-40/Ar-39, Rb-Sr and zircon fission track ages in very low- to low-grade metamorphic rocks in Avalonian SE Cape Breton Island (Nova Scotia, Canada)}, series = {Geological magazine}, volume = {152}, journal = {Geological magazine}, number = {5}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {0016-7568}, doi = {10.1017/S0016756814000508}, pages = {767 -- 787}, year = {2015}, abstract = {Ar-40/Ar-39 in situ UV laser ablation of white mica, Rb-Sr mineral isochrons and zircon fission track dating were applied to determine ages of very low- to low-grade metamorphic processes at 3.5 +/- 0.4 kbar, 280 +/- 30 degrees C in the Avalonian Mira terrane of SE Cape Breton Island (Nova Scotia). The Mira terrane comprises Neoproterozoic volcanic-arc rocks overlain by Cambrian sedimentary rocks. Crystallization of metamorphic white mica was dated in six metavolcanic samples by Ar-40/Ar-39 spot age peaks between 396 +/- 3 and 363 +/- 14 Ma. Rb-Sr systematics of minerals and mineral aggregates yielded two isochrons at 389 +/- 7 Ma and 365 +/- 8 Ma, corroborating equilibrium conditions during very low- to low-grade metamorphism. The dated white mica is oriented parallel to foliations produced by sinistral strike-slip faulting and/or folding related to the Middle-Late Devonian transpressive assembly of Avalonian terranes during convergence and emplacement of the neighbouring Meguma terrane. Exhumation occurred earlier in the NW Mira terrane than in the SE. Transpression was related to the closure of the Rheic Ocean between Gondwana and Laurussia by NW-directed convergence. The Ar-40/Ar-39 spot age spectra also display relict age peaks at 477-465 Ma, 439 Ma and 420-428 Ma attributed to deformation and fluid access, possibly related to the collision of Avalonia with composite Laurentia or to earlier Ordovician-Silurian rifting. Fission track ages of zircon from Mira terrane samples range between 242 +/- 18 and 225 +/- 21 Ma and reflect late Palaeozoic reburial and reheating close to previous peak metamorphic temperatures under fluid-absent conditions during rifting prior to opening of the Central Atlantic Ocean.}, language = {en} } @misc{ZapataSobelDelPapaetal.2020, author = {Zapata, Sebastian and Sobel, Edward and Del Papa, Cecilia and Glodny, Johannes}, title = {Upper Plate Controls on the Formation of Broken Foreland Basins in the Andean Retroarc Between 26°S and 28°S}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {7}, issn = {1866-8372}, doi = {10.25932/publishup-52382}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-523823}, pages = {24}, year = {2020}, abstract = {Marked along-strike changes in stratigraphy, mountain belt morphology, basement exhumation, and deformation styles characterize the Andean retroarc; these changes have previously been related to spatiotemporal variations in the subduction angle. We modeled new apatite fission track and apatite (U-Th-Sm)/He data from nine ranges located between 26 degrees S and 28 degrees S. Using new and previously published data, we constructed a Cretaceous to Pliocene paleogeographic model that delineates a four-stage tectonic evolution: extensional tectonics during the Cretaceous (120-75 Ma), the formation of a broken foreland basin between 55 and 30 Ma, reheating due to burial beneath sedimentary rocks (18-13 Ma), and deformation, exhumation, and surface uplift during the Late Miocene and the Pliocene (13-3 Ma). Our model highlights how preexisting upper plate structures control the deformation patterns of broken foreland basins. Because retroarc deformation predates flat-slab subduction, we propose that slab anchoring may have been the precursor of Eocene-Oligocene compression in the Andean retroarc. Our model challenges models which consider broken foreland basins and retroarc deformation in the NW Argentinian Andes to be directly related to Miocene flat subduction.}, language = {en} } @article{ZapataSobelDelPapaetal.2020, author = {Zapata, Sebastian and Sobel, Edward and Del Papa, Cecilia and Glodny, Johannes}, title = {Upper Plate Controls on the Formation of Broken Foreland Basins in the Andean Retroarc Between 26°S and 28°S}, series = {Geochemistry, Geophysics, Geosystems}, volume = {21}, journal = {Geochemistry, Geophysics, Geosystems}, number = {7}, publisher = {John Wiley \& Sons, Inc.}, address = {New Jersey}, pages = {22}, year = {2020}, abstract = {Marked along-strike changes in stratigraphy, mountain belt morphology, basement exhumation, and deformation styles characterize the Andean retroarc; these changes have previously been related to spatiotemporal variations in the subduction angle. We modeled new apatite fission track and apatite (U-Th-Sm)/He data from nine ranges located between 26 degrees S and 28 degrees S. Using new and previously published data, we constructed a Cretaceous to Pliocene paleogeographic model that delineates a four-stage tectonic evolution: extensional tectonics during the Cretaceous (120-75 Ma), the formation of a broken foreland basin between 55 and 30 Ma, reheating due to burial beneath sedimentary rocks (18-13 Ma), and deformation, exhumation, and surface uplift during the Late Miocene and the Pliocene (13-3 Ma). Our model highlights how preexisting upper plate structures control the deformation patterns of broken foreland basins. Because retroarc deformation predates flat-slab subduction, we propose that slab anchoring may have been the precursor of Eocene-Oligocene compression in the Andean retroarc. Our model challenges models which consider broken foreland basins and retroarc deformation in the NW Argentinian Andes to be directly related to Miocene flat subduction.}, language = {en} } @misc{GhaniSobelZeilingeretal.2021, author = {Ghani, Humaad and Sobel, Edward and Zeilinger, Gerold and Glodny, Johannes and Zapata, Sebastian and Irum, Irum}, title = {Palaeozoic and Pliocene tectonic evolution of the Salt Range constrained by low-temperature thermochronology}, series = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Zweitver{\"o}ffentlichungen der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {3}, issn = {1866-8372}, doi = {10.25932/publishup-56256}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-562567}, pages = {15}, year = {2021}, abstract = {The Salt Range in Pakistan exposes Precambrian to Pleistocene strata outcropping along the Salt Range Thrust (SRT). To better understand the in-situ Cambrian and Pliocene tectonic evolution of the Pakistan Subhimalaya, we have conducted low-temperature thermochronological analysis using apatite (U-Th-Sm)/He and fission track dating. We combine cooling ages from different samples located along the thrust front of the SRT into a thermal model that shows two major cooling events associated with rifting and regional erosion in the Late Palaeozoic and SRT activity since the Pliocene. Our results suggest that the SRT maintained a long-term average shortening rate of similar to 5-6 mm/yr and a high exhumation rate above the SRT ramp since similar to 4 Ma.}, language = {en} } @article{LeonCardonaParraetal.2018, author = {Leon, Santiago and Cardona, Agustin and Parra, Mauricio and Sobel, Edward and Jaramillo, Juan S. and Glodny, Johannes and Valencia, Victor A. and Chew, David and Montes, Camilo and Posada, Gustavo and Monsalve, Gaspar and Pardo-Trujillo, Andres}, title = {Transition from collisional to subduction-related regimes}, series = {Tectonics}, volume = {37}, journal = {Tectonics}, number = {1}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0278-7407}, doi = {10.1002/2017TC004785}, pages = {119 -- 139}, year = {2018}, abstract = {A geological transect across the suture separating northwestern South America from the Panama Arc helps document the provenance and thermal history of both crustal domains and the suture zone. During middle Miocene, strata were being accumulated over the suture zone between the Panama Arc and the continental margin. Integrated provenance analyses of those middle Miocene strata show the presence of mixed sources that includes material derived from the two major crustal domains: the old northwestern South American orogens and the younger Panama Arc. Coeval moderately rapid exhumation of Upper Cretaceous to Paleogene sediments forming the reference continental margin is suggested from our inverse thermal modeling. Strata within the suture zone are intruded by similar to 12 Ma magmatic arc-related plutons, marking the transition from a collisional orogen to a subduction-related one. Renewed late Miocene to Pliocene acceleration of the exhumation rates is the consequence of a second tectonic pulse, which is likely to be triggered by the onset of a flat-slab subduction of the Nazca plate underneath the northernmost Andes of Colombia, suggesting that late Miocene to Pliocene orogeny in the Northern Andes is controlled by at least two different tectonic mechanisms.}, language = {en} } @article{GhaniSobelZeilingeretal.2020, author = {Ghani, Humaad and Sobel, Edward and Zeilinger, Gerold and Glodny, Johannes and Zapata, Sebastian and Irum, Irum}, title = {Palaeozoic and Pliocene tectonic evolution of the Salt Range constrained by low-temperature thermochronology}, series = {Terra nova}, volume = {33}, journal = {Terra nova}, number = {3}, publisher = {Wiley}, address = {Hoboken}, issn = {0954-4879}, doi = {10.1111/ter.12515}, pages = {293 -- 305}, year = {2020}, abstract = {The Salt Range in Pakistan exposes Precambrian to Pleistocene strata outcropping along the Salt Range Thrust (SRT). To better understand the in-situ Cambrian and Pliocene tectonic evolution of the Pakistan Subhimalaya, we have conducted low-temperature thermochronological analysis using apatite (U-Th-Sm)/He and fission track dating. We combine cooling ages from different samples located along the thrust front of the SRT into a thermal model that shows two major cooling events associated with rifting and regional erosion in the Late Palaeozoic and SRT activity since the Pliocene. Our results suggest that the SRT maintained a long-term average shortening rate of similar to 5-6 mm/yr and a high exhumation rate above the SRT ramp since similar to 4 Ma.}, language = {en} } @article{HalamaGlodnyKonradSchmolkeetal.2018, author = {Halama, Ralf and Glodny, Johannes and Konrad-Schmolke, Matthias and Sudo, Masafumi}, title = {Rb-Sr and in situ Ar-40/Ar-39 dating of exhumation-related shearing and fluid-induced recrystallization in the Sesia zone (Western Alps, Italy)}, series = {Geosphere}, volume = {14}, journal = {Geosphere}, number = {4}, publisher = {American Institute of Physics}, address = {Boulder}, issn = {1553-040X}, doi = {10.1130/GES01521.1}, pages = {1425 -- 1450}, year = {2018}, abstract = {The Sesia zone in the Italian Western Alps is a piece of continental crust that has been subducted to eclogite-facies conditions and records a complex metamorphic history. The exact timing of events and the significance of geochronological information are debated due to the interplay of tectonic, metamorphic, and metasomatic processes. Here we present new geochronological data using Rb-Sr internal mineral isochrons and in situ Ar-40/Ar-39 laser ablation data to provide constraints on the relative importance of fluid-mediated mineral replacement reactions and diffusion for the interpretation of radiogenic isotope signatures, and on the use of these isotopic systems for dating metamorphic and variably deformed rocks. Our study focuses on the shear zone at the contact between two major lithological units of the Sesia zone, the eclogitic micaschists and the gneiss minuti. Metasedimentary rocks of the eclogitic micaschists unit contain phengite with step-like zoning in major element chemistry as evidence for petrologic disequilibrium. Distinct Ar-40/Ar-39 spot ages of relict phengite cores and over-printed rims demonstrate the preservation of individual age domains in the crystals. The eclogitic micaschists also show systematic Sr isotope disequilibria among different phengite populations, so that minimum ages of relict assemblage crystallization can be differentiated from the timing of late increments of deformation. The preservation of these disequilibrium features shows the lack of diffusive re-equilibration and underpins that fluid-assisted dissolution and recrystallization reactions are the main factors controlling the isotope record in these subduction-related metamorphic rocks. Blueschist-facies mylonites record deformation along the major shear zone that separates the eclogitic micaschists from the gneiss minuti. Two Rb-Sr isochrones that comprise several white mica fractions and glaucophane constrain the timing of this deformation and accompanying near-complete blueschist-facies re-equilibration of the Rb-Sr system to 60.1 +/- 0.9 Ma and 60.9 +/- 2.1 Ma, respectively. Overlapping ages in eclogitic micaschists of 60.1 +/- 1.1 (Rb-Sr isochron of sheared matrix assemblage), 58.6 +/- 0.8, and 60.9 +/- 0.4 Ma (white mica Ar-40/Ar-39 inverse isochron ages) support the significance of this age and show that fluid-rock interaction and partial re-equilibration occurred as much as several kilometers away from the shear zone. An earlier equilibration during high-pressure conditions in the eclogitic mica schists is recorded in minimum Rb-Sr ages for relict assemblages (77.2 +/- 0.8 and 72.4 +/- 1.1 Ma) and an Ar-40/Ar-39 inverse isochron age of 75.4 +/- 0.8 Ma for white mica cores, again demonstrating that the two isotope systems provide mutually supporting geochronological information. Local reactivation and recrystallization along the shear zone lasted >15 m.y., as late increments of deformation are recorded in a greenschist-facies mylonite by a Rb-Sr isochron age of 46.5 +/- 0.7 Ma.}, language = {en} } @article{WillnervanStaalZagorevskietal.2018, author = {Willner, Arne P. and van Staal, Cees R. and Zagorevski, A. and Glodny, Johannes and Romer, Rolf L. and Sudo, Masafumi}, title = {Tectonometamorphic evolution along the Iapetus suture zone in Newfoundland}, series = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, volume = {742}, journal = {Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0040-1951}, doi = {10.1016/j.tecto.2018.05.023}, pages = {137 -- 167}, year = {2018}, abstract = {The Red Indian Line (RIL) in central Newfoundland is the suture, where the main tract of the Iapetus Ocean was closed at similar to 452 Ma during accretion of the peri-Gondwanan Victoria arc with the composite active Laurentian margin. The protracted deformation history of this soft collision started at similar to 471 Ma with accretion of oceanic terranes to the active composite Laurentian margin. After Iapetus closure both colliding active margins were progressively deformed and metamorphosed during Silurian and Devonian (Salinic, Acadian and Neoacadian orogenic cycles). Peak conditions of the very low- to medium-grade, heterogeneously distributed metamorphism were determined by pseudosection techniques within the range of 2-7 kbar, 230-450 degrees C during increase of the metamorphic field gradient from similar to 12 degrees C/km to similar to 32 degrees C/km over time. Multiple metamorphic crystallisation stages were dated by white mica Ar-40/Ar-39 spot and plateau ages, additional Rb-Sr mineral isochrons involving white mica and one U/Pb age of titanite. All resulting ages between 439 +/- 4 Ma and 356 +/- 16 Ma postdate the closure of Iapetus. Results differ along two transects: The oldest ages of 443-421 Ma (Salinic orogenic cycle) were observed along the northern transect through the RIL zone with minimal younger overprint. Hence low temperature, intermediate to high pressure conditions (4.0-7.0 kbar, 230-340 degrees C) achieved during Taconic-Salinic underthrusting are well preserved. During Acadian dextral transpression the Taconic-Salinic structural wedge was tilted subvertically. In contrast, rocks along the southern transect through the RIL zone mainly show Acadian ages of 408-390 Ma with local preservation of older ages. Acadian deformation occurred under low temperature/low pressure conditions (similar to 250-450 degrees C, 2.5-4.6 kbar). Also Silurian terrestrial cover rocks were buried under these conditions. Acadian-Neoacadian deformation (393-340 Ma) becomes younger towards the northwest and progressively localized in transcurrent fault zones. This final foreland deformation at shallow crustal level established the Acadian/Neoacadian orogenic front in central Newfoundland slightly northwest of the RIL.}, language = {en} } @misc{WillnerBarrGlodnyetal.2015, author = {Willner, Arne P. and Barr, Sandra M. and Glodny, Johannes and Massonne, Hans-Joachim and Sudo, Masafumi and Thomson, Stuart N. and Van Staal, Cees R. and White, Chris E.}, title = {Effects of fluid flow, cooling and deformation as recorded by 40Ar/39Ar, Rb-Sr and zircon fission track ages in very low- to low-grade metamorphic rocks in Avalonian SE Cape Breton Island (Nova Scotia, Canada)}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch Naturwissenschaftliche Reihe}, number = {584}, doi = {10.25932/publishup-41448}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-414484}, pages = {767 -- 787}, year = {2015}, abstract = {40Ar/39Ar in situ UV laser ablation of white mica, Rb-Sr mineral isochrons and zircon fission track dating were applied to determine ages of very low- to low-grade metamorphic processes at 3.5±0.4 kbar, 280±30°C in the Avalonian Mira terrane of SE Cape Breton Island (Nova Scotia). The Mira terrane comprises Neoproterozoic volcanic-arc rocks overlain by Cambrian sedimentary rocks. Crystallization of metamorphic white mica was dated in six metavolcanic samples by 40Ar/39Ar spot age peaks between 396±3 and 363±14 Ma. Rb-Sr systematics of minerals and mineral aggregates yielded two isochrons at 389±7 Ma and 365±8 Ma, corroborating equilibrium conditions during very low- to low-grade metamorphism. The dated white mica is oriented parallel to foliations produced by sinistral strike-slip faulting and/or folding related to the Middle-Late Devonian transpressive assembly of Avalonian terranes during convergence and emplacement of the neighbouring Meguma terrane. Exhumation occurred earlier in the NW Mira terrane than in the SE. Transpression was related to the closure of the Rheic Ocean between Gondwana and Laurussia by NW-directed convergence. The 40Ar/39Ar spot age spectra also display relict age peaks at 477-465 Ma, 439 Ma and 420-428 Ma attributed to deformation and fluid access, possibly related to the collision of Avalonia with composite Laurentia or to earlier Ordovician-Silurian rifting. Fission track ages of zircon from Mira terrane samples range between 242±18 and 225±21 Ma and reflect late Palaeozoic reburial and reheating close to previous peak metamorphic temperatures under fluid-absent conditions during rifting prior to opening of the Central Atlantic Ocean.}, language = {en} } @article{GhaniSobelZeilingeretal.2021, author = {Ghani, Humaad and Sobel, Edward and Zeilinger, Gerold and Glodny, Johannes and Irum, Irum and Sajid, Muhammad}, title = {Spatio-temporal structural evolution of the Kohat fold and thrust belt of Pakistan}, series = {Journal of structural geology}, volume = {145}, journal = {Journal of structural geology}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, issn = {0191-8141}, doi = {10.1016/j.jsg.2021.104310}, pages = {16}, year = {2021}, abstract = {The Kohat fold and thrust belt in Pakistan shows a significantly different structural style due to the structural evolution on the double d{\´e}collement compared to the rest of the Subhimalaya. In order to better understand the spatio-temporal structural evolution of the Kohat fold and thrust belt, we combine balanced cross sections with apatite (U?Th-Sm)/He (AHe) and apatite fission track (AFT) dating. The AHe and AFT ages appear to be totally reset, allowing us to date exhumation above structural ramps. The results suggest that deformation began on the frontal Surghar thrust at-15 Ma, predating or coeval with the development of the Main Boundary thrust at-12 Ma. Deformation propagated southward from the Main Boundary thrust on double de?collements between 10 Ma and 2 Ma, resulting in a disharmonic structural style inside the Kohat fold and thrust belt. Thermal modeling of the thermochronologic data suggest that samples inside Kohat fold and thrust belt experienced cooling due to formation of the duplexes; this deformation facilitated tectonic thickening of the wedge and erosion of the Miocene to Pliocene foreland strata. The spatial distribution of AHe and AFT ages in combination with the structural forward model suggest that, in the Kohat fold and thrust belt, the wedge deformed in-sequence as a supercritical wedge (-15-12 Ma), then readjusted by out-sequence deformation (-12-0 Ma) within the Kohat fold and thrust belt into a sub-critical wedge.}, language = {en} } @article{EzpeletaParraColloetal.2022, author = {Ezpeleta, Miguel and Parra, Mauricio and Collo, Gilda and Wunderlin, Cecilia and Borrego, Angeles G. and Sobel, Edward and Glodny, Johannes}, title = {Thermochronometry unveils ancient thermal regimes in the NW Pampean Ranges, Argentina}, series = {Basin research}, volume = {34}, journal = {Basin research}, number = {6}, publisher = {Wiley}, address = {Hoboken}, issn = {0950-091X}, doi = {10.1111/bre.12693}, pages = {1983 -- 2012}, year = {2022}, abstract = {Reconstructing thermal histories in thrust belts is commonly used to infer the age and rates of thrusting and hence the driving mechanisms of orogenesis. In areas where ancient basins have been incorporated into the orogenic wedge, a quantitative reconstruction of the thermal history helps distinguish among potential mechanisms responsible for heating events. We present such a reconstruction for the Ischigualasto-Villa Union basin in the western Pampean Ranges of Argentina, where Triassic rifting and late Cretaceous-Cenozoic retroarc foreland basin development has been widely documented, including Miocene flat-slab subduction. We report results of organic and inorganic thermal indicators acquired along three stratigraphic sections, including vitrinite reflectance and X-ray diffractometry in claystones and new thermochronological [(apatite fission-track and apatite and zircon [U-Th]/He)] analyses. Despite up to 5 km-thick Cenozoic overburden and unlike previously thought, the thermal peak in the basin is not due to Cenozoic burial but occurred in the Triassic, associated with a high heat flow of up to 90 mWm(-2) and <2 km of burial, which heated the base of the Triassic strata to similar to 160 degrees C. Following exhumation, attested by the development of an unconformity between the Triassic and Late-Cretaceous-Cenozoic sequences, Cenozoic re-burial increased the temperature to similar to 110 degrees C at the base of the Triassic section and only similar to 50 degrees C 7 km upsection, suggesting a dramatic decrease in the thermal gradient. The onset of Cenozoic cooling occurred at similar to 10(-8) Ma, concomitant with sediment accumulation and thus preceding the latest Miocene onset of thrusting that has been independently documented by stratigraphic-cross-cutting relationships. We argue that the onset of cooling is associated with lithospheric refrigeration following establishment of flat-slab subduction, leading to the eastward displacement of the asthenospheric wedge beneath the South American plate. Our study places time and temperature constraints on flat-slab cooling that calls for a careful interpretation of exhumation signals in thrustbelts inferred from thermochronology only.}, language = {en} } @article{PerezConsuegraHokeFitzgeraldetal.2022, author = {Perez-Consuegra, Nicolas and Hoke, Gregory D. and Fitzgerald, P. and Mora, Andres and Sobel, Edward R. and Glodny, Johannes}, title = {Late Miocene-Pliocene onset of fluvial incision of the Cauca River Canyon in the Northern Andes}, series = {Geological Society of America bulletin}, volume = {134}, journal = {Geological Society of America bulletin}, number = {9-10}, publisher = {American Institute of Physics}, address = {Boulder}, issn = {0016-7606}, doi = {10.1130/B36047.1}, pages = {2453 -- 2468}, year = {2022}, abstract = {The incision of kilometer-scale canyons into high-standing topography is often used to constrain the surface uplift history of mountain ranges, controlled by tectonic and geodynamic processes. However, changes in climate may also be responsible for canyon incision. This study deciphers the timing of incision of the similar to 2.5-km-deep Cauca River Canyon in the Central Cordillera of the Northern Andes using the cooling (exhumation) history of rocks from the canyon walls and a regional analysis of channel steepness in rivers. Ten bedrock samples and one detrital sample were collected on the eastern border of the canyon between 300 m and 2300 m of elevation. Bedrock and detrital AFT data yield ages from 50 to 38 Ma, while two bed-rock AHe ages from the valley bottom yield ages of 7-6 Ma. The AHe ages and inverse thermal history models reveal a previously unidentified late Miocene (ca. 7-6 Ma) pulse of exhumation that we interpret as the age of a single incision event that formed the Cauca River Canyon. We conclude that the Cauca River Canyon was carved as a response to rock uplift in the northern Central Cordillera and propagation of an erosion wave into the mountain range starting in the latest Miocene.}, language = {en} }