TY - JOUR A1 - Pourteau, Amaury A1 - Scherer, Erik E. A1 - Schorn, Simon A1 - Bast, Rebecca A1 - Schmidt, Alexander A1 - Ebert, Lisa T1 - Thermal evolution of an ancient subduction interface revealed by Lu-Hf garnet geochronology, Halilbagi Complex (Anatolia) JF - Geoscience Frontiers N2 - The thermal structure of subduction zones exerts a major influence on deep-seated mechanical and chemical processes controlling arc magmatism, seismicity, and global element cycles. Accretionary complexes exposed inland may comprise tectonic blocks with contrasting pressure-temperature (P-T) histories, making it possible to investigate the dynamics and thermal evolution of former subduction interfaces. With this aim, we present new Lu-Hf geochronological results for mafic rocks of the Halilbagi Complex (Anatolia) that evolved along different thermal gradients. Samples include a lawsonite-epidote blueschist, a lawsonite-epidote eclogite, and an epidote eclogite (all with counter-clockwise P-T paths), a prograde lawsonite blueschist with a "hairpin"-type P-T path, and a garnet amphibolite from the overlying sub-ophiolitic metamorphic sole. Equilibrium phase diagrams suggest that the garnet amphibolite formed at similar to 0.6-0.7 GPa and 800-850 degrees C, whereas the prograde lawsonite blueschist records burial from 2.1 GPa and 420 degrees C to 2.6 GPa and 520 degrees C. Well-defined Lu-Hf isochrons were obtained for the epidote eclogite (92.38 +/- 0.22 Ma) and the lawsonite-epidote blueschist (90.19 +/- 0.54 Ma), suggesting rapid garnet growth. The lawsonite-epidote eclogite (87.30 +/- 0.39 Ma) and the prograde lawsonite blueschist (ca. 86 Ma) are younger, whereas the garnet amphibolite (104.5 +/- 3.5 Ma) is older. Our data reveal a consistent trend of progressively decreasing geothermal gradient from granulite-facies conditions at similar to 104 Ma to the epidote-eclogite facies around 92 Ma, and the lawsonite blueschist-facies between 90 Ma and 86 Ma. Three Lu-Hf garnet dates (between 92 Ma and 87 Ma) weighted toward the growth of post-peak rims (as indicated by Lu distribution in garnet) suggest that the HP/LT rocks were exhumed continuously and not episodically. We infer that HP/LT metamorphic rocks within the Halilbagi Complex were subjected to continuous return flow, with "warm" rocks being exhumed during the tectonic burial of "cold" ones. Our results, combined with regional geological constraints, allow us to speculate that subduction started at a transform fault near a mid-oceanic spreading centre. Following its formation, this ancient subduction interface evolved thermally over more than 15 Myr, most likely as a result of heat dissipation rather than crustal underplating. (C) 2018, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. KW - Subduction KW - Lu/Hf dating of garnet KW - Metamorphic sole KW - Eclogite KW - Blueschist KW - Lawsonite Y1 - 2019 U6 - https://doi.org/10.1016/j.gsf.2018.03.004 SN - 1674-9871 VL - 10 IS - 1 SP - 127 EP - 148 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Barth, Sophia A1 - Geertsema, Marten A1 - Bevington, Alexandre R. A1 - Bird, Alison L. A1 - Clague, John J. A1 - Millard, Tom A1 - Bobrowsky, Peter T. A1 - Hasler, Andreas A1 - Liu, Hongjiang T1 - Landslide response to the 27 October 2012 earthquake (M-W 7.8), southern Haida Gwaii, British Columbia, Canada JF - Landslides : journal of the International Consortium on Landslides, ICL N2 - In this paper, we examine the influence of the 27 October 2012, M-w 7.8 earthquake on landslide occurrence in the southern half of Haida Gwaii (formerly Queen Charlotte Islands), British Columbia, Canada. Our 1350 km(2) study area is undisturbed, primarily forested terrain that has not experienced road building or timber harvesting. Our inventory of landslide polygons is based on optical airborne and spaceborne images acquired between 2007 and 2018, from which we extracted and mapped 446 individual landslides (an average of 33 landslides per 100 km(2)). The landslide rate in years without major earthquakes averages 19.4 per year, or 1.4/100 km(2)/year, and the annual average area covered by non-seismically triggered landslides is 35 ha/year. The number of landslides identified in imagery closely following the 2012 earthquake, and probably triggered by it, is 244 or an average of about 18 landslides per 100 km(2). These landslides cover a total area of 461 ha. In the following years-2013-2016 and 2016-2018-the number of landslides fell, respectively, to 26 and 13.5 landslides per year. In non-earthquake years, most landslides happen on south-facing slopes, facing the prevailing winds. In contrast, during or immediately after the earthquake, up to 32% of the landslides occurred on north and northwest-facing slopes. Although we could not find imagery from the day after the earthquake, overview reconnaissance flights 10 and 16 days later showed that most of the landslides were recent, suggesting they were co-seismic. KW - Landslide KW - Earthquake KW - British Columbia KW - Haida Gwaii Y1 - 2019 U6 - https://doi.org/10.1007/s10346-019-01292-7 SN - 1612-510X SN - 1612-5118 VL - 17 IS - 3 SP - 517 EP - 526 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Herzschuh, Ulrike T1 - Legacy of the Last Glacial on the present-day distribution of deciduous versus evergreen boreal forests JF - Global ecology and biogeography : a journal of macroecology N2 - Issue Despite their rather similar climatic conditions, eastern Eurasia and northern North America are largely covered by different plant functional types (deciduous or evergreen boreal forest) composed of larch or pine, spruce and fir, respectively. I propose that these deciduous and evergreen boreal forests represent alternative quasi-stable states, triggered by their different northern tree refugia that reflect the different environmental conditions experienced during the Last Glacial. Evidence This view is supported by palaeoecological and environmental evidence. Once established, Asian larch forests are likely to have stabilized through a complex vegetation-fire-permafrost soil-climate feedback system. Conclusion With respect to future forest developments, this implies that Asian larch forests are likely to be governed by long-term trajectories and are therefore largely resistant to natural climate variability on time-scales shorter than millennia. The effects of regional human impact and anthropogenic global warming might, however, cause certain stability thresholds to be crossed, meaning that irreversible transitions occur and resulting in marked consequences for ecosystem services on these human-relevant time-scales. KW - boreal forests KW - Glacial refugia KW - Holocene KW - Larix larch KW - permafrost ecosystems KW - Palaeoecology KW - Siberia KW - vegetation-climate-fire-soil feedbacks KW - vegetation states KW - vegetation trajectories Y1 - 2018 U6 - https://doi.org/10.1111/geb.13018 SN - 1466-822X SN - 1466-8238 VL - 29 IS - 2 SP - 198 EP - 206 PB - John Wiley & Sons, Inc. CY - Hoboken ER - TY - JOUR A1 - Sublett, David Matthew A1 - Sendula, Eszter A1 - Lamadrid, Hector A1 - Steele-MacInnis, Matthew A1 - Spiekermann, Georg A1 - Burruss, Robert C. A1 - Bodnar, Robert J. T1 - Shift in the Raman symmetric stretching band of N-2, CO2, and CH4 as a function of temperature, pressure, and density JF - Journal of Raman spectroscopy : JRS N2 - The Raman spectra of pure N-2, CO2, and CH4 were analyzed over the range 10 to 500 bars and from -160 degrees C to 200 degrees C (N-2), 22 degrees C to 350 degrees C (CO2), and -100 degrees C to 450 degrees C (CH4). At constant temperature, Raman peak position, including the more intense CO2 peak (nu+), decreases (shifts to lower wave number) with increasing pressure for all three gases over the entire pressure and temperature (PT) range studied. At constant pressure, the peak position for CO2 and CH4 increases (shifts to higher wave number) with increasing temperature over the entire PT range studied. In contrast, N-2 first shows an increase in peak position with increasing temperature at constant pressure, followed by a decrease in peak position with increasing temperature. The inflection temperature at which the trend reverses for N-2 is located between 0 degrees C and 50 degrees C at pressures above similar to 50 bars and is pressure dependent. Below similar to 50 bars, the inflection temperature was observed as low as -120 degrees C. The shifts in Raman peak positions with PT are related to relative density changes, which reflect changes in intermolecular attraction and repulsion. A conceptual model relating the Raman spectral properties of N-2, CO2, and CH4 to relative density (volume) changes and attractive and repulsive forces is presented here. Additionally, reduced temperature-dependent densimeters and barometers are presented for each pure component over the respective PT ranges. The Raman spectral behavior of the pure gases as a function of temperature and pressure is assessed to provide a framework for understanding the behavior of each component in multicomponent N-2-CO2-CH4 gas systems in a future study. KW - fluids KW - wave number KW - attraction KW - repulsion Y1 - 2019 U6 - https://doi.org/10.1002/jrs.5805 SN - 0377-0486 SN - 1097-4555 VL - 51 IS - 3 SP - 555 EP - 568 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Tolorza, Violeta A1 - Mohr, Christian Heinrich A1 - Carretier, Sebastien A1 - Serey, Amador A1 - Sepulveda, Sergio A. A1 - Tapia, Joseline A1 - Pinto, Luisa T1 - Suspended sediments in chilean rivers reveal low postseismic erosion after the maule earthquake (Mw 8.8) during a severe drought JF - Journal of geophysical research : Earth surface N2 - We address the question of whether all large-magnitude earthquakes produce an erosion peak in the subaerial components of fluvial catchments. We evaluate the sediment flux response to the Maule earthquake in the Chilean Andes (Mw 8.8) using daily suspended sediment records from 31 river gauges. The catchments cover drainage areas of 350 to around 10,000 km(2), including a wide range of topographic slopes and vegetation cover of the Andean western flank. We compare the 3- to 8-year postseismic record of sediment flux to each of the following preseismic periods: (1) all preseismic data, (2) a 3-year period prior to the seismic event, and (3) the driest preseismic periods, as drought conditions prevailed in the postseismic period. Following the earthquake, no increases in suspended sediment flux were observed for moderate to high percentiles of the streamflow distribution (mean, median, and >= 75th percentile). However, more than half of the examined stations showed increased sediment flux during baseflow. By using a Random Forest approach, we evaluate the contributions of seismic intensities, peak ground accelerations, co-seismic landslides, hydroclimatic conditions, topography, lithology, and land cover to explain the observed changes in suspended sediment concentration and fluxes. We find that the best predictors are hillslope gradient, low-vegetation cover, and changes in streamflow discharge. This finding suggests a combined first-order control of topography, land cover, and hydrology on the catchment-wide erosion response. We infer a reduced sediment connectivity due to the postseismic drought, which increased the residence time of sediment detached and remobilized following the Maule earthquake. KW - earthquake KW - suspended sediment KW - Maule megathrust KW - Chile KW - catchment Y1 - 2019 U6 - https://doi.org/10.1029/2018JF004766 SN - 2169-9003 SN - 2169-9011 VL - 124 IS - 6 SP - 1378 EP - 1397 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Fortesa, Josep A1 - García-Comendador, Julian A1 - Calsamiglia, A. A1 - López-Tarazón, José Andrés A1 - Latron, J. A1 - Alorda, B. A1 - Estrany, Joan T1 - Comparison of stage/discharge rating curves derived from different recording systems BT - Consequences for streamflow data and water management in a Mediterranean island JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - Obtaining representative hydrometric values is essential for characterizing extreme events, hydrological dynamics and detecting possible changes on the long-term hydrology. Reliability of streamflow data requires a temporal continuity and a maintenance of the gauging stations, which data are affected by epistemic and random sources of error. An assessment of discharge meterings' and stage-discharge rating curves' uncertainties were carried out by comparing the accuracy of the measuring instruments of two different hydrometric networks (i.e., one analogical and one digital) established in the same river location at the Mediterranean island of Mallorca. Furthermore, the effects of such uncertainties were assessed on the hydrological dynamics, considering the significant global change impacts beset this island. Evaluation was developed at four representative gauging stations of the hydrographic network with analogic (≈40 years) and digital (≈10 years) data series. The study revealed that the largest source of uncertainty in the analogical (28 to 274%) and in the digital (17–37%) networks were the stage-discharge rating curves. Their impact on the water resources was also evaluated at the event and annual scales, resulting in an average difference of water yields of 183% and 142% respectively. Such improvement on the comprehension of hydrometric networks uncertainties will dramatically benefit the interpretation of the long-term streamflow by providing better insights into the hydrologic and flood hazard planning, management and modelling. KW - Hydrometric networks KW - Stage-discharge KW - Metering KW - Uncertainty KW - Error propagation Y1 - 2019 U6 - https://doi.org/10.1016/j.scitotenv.2019.02.158 SN - 0048-9697 SN - 1879-1026 VL - 665 SP - 968 EP - 981 PB - Elsevier Science CY - Amsterdam ER - TY - JOUR A1 - Wickert, Andrew D. A1 - Schildgen, Taylor F. T1 - Long-profile evolution of transport-limited gravel-bed rivers JF - Earth surface dynamics N2 - Alluvial and transport-limited bedrock rivers constitute the majority of fluvial systems on Earth. Their long profiles hold clues to their present state and past evolution. We currently possess first-principles-based governing equations for flow, sediment transport, and channel morphodynamics in these systems, which we lack for detachment-limited bedrock rivers. Here we formally couple these equations for transport-limited gravel-bed river long-profile evolution. The result is a new predictive relationship whose functional form and parameters are grounded in theory and defined through experimental data. From this, we produce a power-law analytical solution and a finite-difference numerical solution to long-profile evolution. Steady-state channel concavity and steepness are diagnostic of external drivers: concavity decreases with increasing uplift rate, and steepness increases with an increasing sediment-to-water supply ratio. Constraining free parameters explains common observations of river form: to match observed channel concavities, gravel-sized sediments must weather and fine - typically rapidly - and valleys typically should widen gradually. To match the empirical square-root width-discharge scaling in equilibrium-width gravel-bed rivers, downstream fining must occur. The ability to assign a cause to such observations is the direct result of a deductive approach to developing equations for landscape evolution. Y1 - 2019 U6 - https://doi.org/10.5194/esurf-7-17-2019 SN - 2196-6311 SN - 2196-632X VL - 7 IS - 1 SP - 17 EP - 43 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Kaczorek, Danuta A1 - Puppe, Daniel A1 - Busse, Jacqueline A1 - Sommer, Michael T1 - Effects of phytolith distribution and characteristics on extractable silicon fractions in soils under different vegetation - An exploratory study on loess JF - Geoderma : an international journal of soil science N2 - The significance of phytoliths for the control of silicon (Si) fluxes from terrestrial to aquatic ecosystems has been recognized as a key factor. Humankind actively influences Si fluxes by intensified land use, i.e., agriculture and forestry, on a global scale. We hypothesized phytolith distribution and assemblages in soils of agricultural and forestry sites to be controlled by vegetation (which is directed by land use) with direct effects on extractable Si fractions driven mainly by phytolith characteristics, i.e., dissolution status (dissolution signs) and morphology (morphotype proportions). To test our hypothesis we combined different chemical extraction methods (calcium chloride, ammonium oxalate, Tiron) for the quantification of different Si fractions (plant available Si, Si adsorbed to/occluded in pedogenic oxides/hydroxides, amorphous Si) and microscopic techniques (light microscopy, confocal laser scanning microscopy, scanning electron microscopy) for detailed analyses of phytoliths extracted using gravimetric separation (physical extraction) from exemplary loess soils of agricultural (arable land and grassland/meadow) and forestry (beech and pine) sites in Poland. We found differences in dissolution signs, morphotype proportions, and vertical distribution of phytoliths in soil horizons per site. In general, dominant morphotypes of assignable phytoliths in the studied soil profiles were elongate phytoliths and short cells, both of which are typical for grass-dominated vegetation. However, the organic layers of forest soils were dominated by globular phytoliths, which are typical indicators for mosses. As expected soil horizons under different vegetation generally were characterized by differences in extractable Si fractions, especially in the upper soil horizons. However, phytogenic Si pools counter-intuitively showed no correlations with chemically extracted Si fractions and soil pH at all. Our findings indicate that it is necessary to combine microscopic analyses and Si extraction techniques for examinations of Si cycling in biogeosystems, because extractions of Si fractions alone do not allow drawing any conclusions about phytolith characteristics or interactions between phytolith pools and chemically extractable Si fractions and do not necessarily reflect phytogenic Si pool quantities in soils and vice versa. KW - Phytolith dissolution KW - Phytolith morphotypes KW - Si extraction KW - Surface roughness parameters KW - Si cycling Y1 - 2019 U6 - https://doi.org/10.1016/j.geoderma.2019.113917 SN - 0016-7061 SN - 1872-6259 VL - 356 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bufe, Aaron A1 - Turowski, Jens M. A1 - Burbank, Douglas W. A1 - Paola, Chris A1 - Wickert, Andrew D. A1 - Tofelde, Stefanie T1 - Controls on the lateral channel-migration rate of braided channel systems in coarse non-cohesive sediment JF - Earth surface processes and landforms : the journal of the British Geomorphological Research Group N2 - Lateral movements of alluvial river channels control the extent and reworking rates of alluvial fans, floodplains, deltas, and alluvial sections of bedrock rivers. These lateral movements can occur by gradual channel migration or by sudden changes in channel position (avulsions). Whereas models exist for rates of river avulsion, we lack a detailed understanding of the rates of lateral channel migration on the scale of a channel belt. In a two-step process, we develop here an expression for the lateral migration rate of braided channel systems in coarse, non-cohesive sediment. On the basis of photographic and topographic data from laboratory experiments of braided channels performed under constant external boundary conditions, we first explore the impact of autogenic variations of the channel-system geometry (i.e. channel-bank heights, water depths, channel-system width, and channel slope) on channel-migration rates. In agreement with theoretical expectations, we find that, under such constant boundary conditions, the laterally reworked volume of sediment is constant and lateral channel-migration rates scale inversely with the channel-bank height. Furthermore, when channel-bank heights are accounted for, lateral migration rates are independent of the remaining channel geometry parameters. These constraints allow us, in a second step, to derive two alternative expressions for lateral channel-migration rates under different boundary conditions using dimensional analysis. Fits of a compilation of laboratory experiments to these expressions suggest that, for a given channel bank-height, migration rates are strongly sensitive to water discharges and more weakly sensitive to sediment discharges. In addition, external perturbations, such as changes in sediment and water discharges or base level fall, can indirectly affect lateral channel-migration rates by modulating channel-bank heights. KW - braided alluvial rivers KW - physical experiments KW - channel migration Y1 - 2019 U6 - https://doi.org/10.1002/esp.4710 SN - 0197-9337 SN - 1096-9837 VL - 44 IS - 14 SP - 2823 EP - 2836 PB - Wiley CY - Hoboken ER - TY - GEN A1 - Braun, David R. A1 - Aldeias, Vera A1 - Archer, Will A1 - Arrowsmith, J. Ramon A1 - Baraki, Niguss A1 - Campisano, Christopher J. A1 - Deino, Alan L. A1 - DiMaggio, Erin N. A1 - Dupont-Nivet, Guillaume A1 - Engda, Blade A1 - Feary, David A. A1 - Garello, Dominique I. A1 - Kerfelew, Zenash A1 - McPherron, Shannon P. A1 - Patterson, David B. A1 - Reeves, Jonathan S. A1 - Thompson, Jessica C. A1 - Reed, Kaye E. T1 - Reply to Sahle and Gossa: Technology and geochronology at the earliest known Oldowan site at Ledi-Geraru, Ethiopia T2 - Proceedings of the National Academy of Sciences of the United States of America Y1 - 2019 U6 - https://doi.org/10.1073/pnas.1911952116 SN - 0027-8424 N1 - Letter VL - 116 IS - 41 SP - 20261 EP - 20262 PB - National Acad. of Sciences CY - Washington ER - TY - JOUR A1 - Guillemoteau, Julien A1 - Simon, Francois-Xavier A1 - Hulin, Guillaume A1 - Dousteyssier, Bertrand A1 - Dacko, Marion A1 - Tronicke, Jens T1 - 3-D imaging of subsurface magnetic permeability/susceptibility with portable frequency domain electromagnetic sensors for near surface exploration JF - Geophysical journal international N2 - The in-phase response collected by portable loop-loop electromagnetic induction (EMI) sensors operating at low and moderate induction numbers (<= 1) is typically used for sensing the magnetic permeability (or susceptibility) of the subsurface. This is due to the fact that the in-phase response contains a small induction fraction and a preponderant induced magnetization fraction. The magnetization fraction follows the magneto-static equations similarly to the magnetic method but with an active magnetic source. The use of an active source offers the possibility to collect data with several loop-loop configurations, which illuminate the subsurface with different sensitivity patterns. Such multiconfiguration soundings thereby allows the imaging of subsurface magnetic permeability/susceptibility variations through an inversion procedure. This method is not affected by the remnant magnetization and theoretically overcomes the classical depth ambiguity generally encountered with passive geomagnetic data. To invert multiconfiguration in-phase data sets, we propose a novel methodology based on a full-grid 3-D multichannel deconvolution (MCD) procedure. This method allows us to invert large data sets (e.g. consisting of more than a hundred thousand of data points) for a dense voxel-based 3-D model of magnetic susceptibility subject to smoothness constraints. In this study, we first present and discuss synthetic examples of our imaging procedure, which aim at simulating realistic conditions. Finally, we demonstrate the applicability of our method to field data collected across an archaeological site in Auvergne (France) to image the foundations of a Gallo-Roman villa built with basalt rock material. Our synthetic and field data examples demonstrate the potential of the proposed inversion procedure offering new and complementary ways to interpret data sets collected with modern EMI instruments. KW - Magnetic properties KW - Controlled source electromagnetics (CSEM) KW - Electromagnetic theory KW - Environmental magnetism KW - Inverse theory Y1 - 2019 U6 - https://doi.org/10.1093/gji/ggz382 SN - 0956-540X SN - 1365-246X VL - 219 IS - 3 SP - 1773 EP - 1785 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Westerweel, Jan A1 - Roperch, Pierrick A1 - Licht, Alexis A1 - Dupont-Nivet, Guillaume A1 - Win, Zaw A1 - Poblete, Fernando A1 - Ruffet, Gilles A1 - Swe, Hnin Hnin A1 - Thi, Myat Kai A1 - Aung, Day Wa T1 - Burma Terrane part of the Trans-Tethyan arc during collision with India according to palaeomagnetic data JF - Nature geoscience N2 - Convergence between the Indian and Asian plates has reshaped large parts of Asia, changing regional climate and biodiversity, yet geodynamic models fundamentally diverge on how convergence was accommodated since the India-Asia collision. Here we report palaeomagnetic data from the Burma Terrane, which is at the eastern edge of the collision zone and is famous for its Cretaceous amber biota, to better determine the evolution of the India-Asia collision. The Burma Terrane was part of a Trans-Tethyan island arc and stood at a near-equatorial southern latitude at similar to 95 Ma, suggesting island endemism for the Burmese amber biota. The Burma Terrane underwent significant clockwise rotation between similar to 80 and 50 Ma, causing its subduction margin to become hyper-oblique. Subsequently, it was translated northward on the Indian Plate by an exceptional distance of at least 2,000 km along a dextral strike-slip fault system in the east. Our reconstructions are only compatible with geodynamic models involving an initial collision of India with a near-equatorial Trans-Tethyan subduction system at similar to 60 Ma, followed by a later collision with the Asian margin. Y1 - 2019 U6 - https://doi.org/10.1038/s41561-019-0443-2 SN - 1752-0894 SN - 1752-0908 VL - 12 IS - 10 SP - 863 EP - 868 PB - Nature Publ. Group CY - New York ER - TY - JOUR A1 - Carvalho, Bruna B. A1 - Bartoli, Omar A1 - Ferri, Fabio A1 - Cesare, Bernardo A1 - Ferrero, Silvio A1 - Remusat, Laurent A1 - Capizzi, Luca Samuele A1 - Poli, Stefano T1 - Anatexis and fluid regime of the deep continental crust: New clues from melt and fluid inclusions in metapelitic migmatites from Ivrea Zone (NW Italy) JF - Journal of metamorphic geology N2 - We investigate the inclusions hosted in peritectic garnet from metapelitic migmatites of the Kinzigite Formation (Ivrea Zone, NW Italy) to evaluate the starting composition of the anatectic melt and fluid regime during anatexis throughout the upper amphibolite facies, transition, and granulite facies zones. Inclusions have negative crystal shapes, sizes from 2 to 10 mu m and are regularly distributed in the core of the garnet. Microstructural and micro-Raman investigations indicate the presence of two types of inclusions: crystallized silicate melt inclusions (i.e., nanogranitoids, NI), and fluid inclusions (FI). Microstructural evidence suggests that FI and NI coexist in the same cluster and are primary (i.e., were trapped simultaneously during garnet growth). FI have similar compositions in the three zones and comprise variable proportions of CO2, CH4, and N-2, commonly with siderite, pyrophyllite, and kaolinite, suggesting a COHN composition of the trapped fluid. The mineral assemblage in the NI contains K-feldspar, plagioclase, quartz, biotite, muscovite, chlorite, graphite and, rarely, calcite. Polymorphs such as kumdykolite, cristobalite, tridymite, and less commonly kokchetavite, were also found. Rehomogenized NI from the different zones show that all the melts are leucogranitic but have slightly different compositions. In samples from the upper amphibolite facies, melts are less mafic (FeO + MgO = 2.0-3.4 wt%), contain 860-1700 ppm CO2 and reach the highest H2O contents (6.5-10 wt%). In the transition zone melts have intermediate H2O (4.8-8.5 wt%), CO2 (457-1534 ppm) and maficity (FeO + MgO = 2.3-3.9 wt%). In contrast, melts at granulite facies reach highest CaO, FeO + MgO (3.2-4.7 wt%), and CO2 (up to 2,400 ppm), with H2O contents comparable (5.4-8.3 wt%) to the other two zones. Our results represent the first clear evidence for carbonic fluid-present melting in the Ivrea Zone. Anatexis of metapelites occurred through muscovite and biotite breakdown melting in the presence of a COH fluid, in a situation of fluid-melt immiscibility. The fluid is assumed to have been internally derived, produced initially by devolatilization of hydrous silicates in the graphitic protolith, then as a result of oxidation of carbon by consumption of Fe3+-bearing biotite during melting. Variations in the compositions of the melts are interpreted to result from higher T of melting. The H2O contents of the melts throughout the three zones are higher than usually assumed for initial H2O contents of anatectic melts. The CO2 contents are highest at granulite facies, and show that carbon-contents of crustal magmas are not negligible at high T. The activity of H2O of the fluid dissolved in granitic melts decreases with increasing metamorphic grade. Carbonic fluid-present melting of the deep continental crust represents, together with hydrate-breakdown melting reactions, an important process in the origin of crustal anatectic granitoids. KW - anatexis KW - fluid inclusions KW - fluid regime KW - Ivrea Zone KW - melt inclusions Y1 - 2019 U6 - https://doi.org/10.1111/jmg.12463 SN - 0263-4929 SN - 1525-1314 VL - 37 IS - 7 SP - 951 EP - 975 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Mueller, Megan A. A1 - Licht, Alexis A1 - Campbell, C. A1 - Ocakoglu, F. A1 - Taylor, Marc Hollis A1 - Burch, L. A1 - Ugrai, Tamas A1 - Kaya, M. A1 - Kurtoglu, B. A1 - Coster, P. M. C. A1 - Metais, Mustafa Yücel A1 - Beard, Kenneth Christopher T1 - Collision Chronology Along the Izmir-Ankara-Erzincan Suture Zone: Insights From the Saricakaya Basin, Western Anatolia JF - Tectonics N2 - Debate persists concerning the timing and geodynamics of intercontinental collision, style of syncollisional deformation, and development of topography and fold-and-thrust belts along the >1,700-km-long Izmir-Ankara-Erzincan suture zone (IAESZ) in Turkey. Resolving this debate is a necessary precursor to evaluating the integrity of convergent margin models and kinematic, topographic, and biogeographic reconstructions of the Mediterranean domain. Geodynamic models argue either for a synchronous or diachronous collision during either the Late Cretaceous and/or Eocene, followed by Eocene slab breakoff and postcollisional magmatism. We investigate the collision chronology in western Anatolia as recorded in the sedimentary archives of the 90-km-long Saricakaya Basin perched at shallow structural levels along the IAESZ. Based on new zircon U-Pb geochronology and depositional environment and sedimentary provenance results, we demonstrate that the Saricakaya Basin is an Eocene sedimentary basin with sediment sourced from both the IAESZ and Sogut Thrust fault to the south and north, respectively, and formed primarily by flexural loading from north-south shortening along the syncollisional Sogut Thrust. Our results refine the timing of collision between the Anatolides and Pontide terranes in western Anatolia to Maastrichtian-Middle Paleocene and Early Eocene crustal shortening and basin formation. Furthermore, we demonstrate contemporaneous collision, deformation, and magmatism across the IAESZ, supporting synchronous collision models. We show that regional postcollisional magmatism can be explained by renewed underthrusting instead of slab breakoff. This new IAESZ chronology provides additional constraints for kinematic, geodynamic, and biogeographic reconstructions of the Mediterranean domain. KW - Anatolia KW - geochronology KW - collision KW - Eocene KW - detrital zircons Y1 - 2019 U6 - https://doi.org/10.1029/2019TC005683 SN - 0278-7407 SN - 1944-9194 VL - 38 IS - 10 SP - 3652 EP - 3674 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Aichner, Bernhard A1 - Makhmudov, Zafar A1 - Rajabov, Iljomjon A1 - Zhang, Qiong A1 - Pausata, Francesco Salvatore R. A1 - Werner, Martin A1 - Heinecke, Liv A1 - Kuessner, Marie L. A1 - Feakins, Sarah J. A1 - Sachse, Dirk A1 - Mischke, Steffen T1 - Hydroclimate in the Pamirs Was Driven by Changes in Precipitation-Evaporation Seasonality Since theLast Glacial Period JF - Geophysical research letters N2 - The Central Asian Pamir Mountains (Pamirs) are a high-altitude region sensitive to climatic change, with only few paleoclimatic records available. To examine the glacial-interglacial hydrological changes in the region, we analyzed the geochemical parameters of a 31-kyr record from Lake Karakul and performed a set of experiments with climate models to interpret the results. delta D values of terrestrial biomarkers showed insolation-driven trends reflecting major shifts of water vapor sources. For aquatic biomarkers, positive delta D shifts driven by changes in precipitation seasonality were observed at ca. 31-30, 28-26, and 17-14 kyr BP. Multiproxy paleoecological data and modelling results suggest that increased water availability, induced by decreased summer evaporation, triggered higher lake levels during those episodes, possibly synchronous to northern hemispheric rapid climate events. We conclude that seasonal changes in precipitation-evaporation balance significantly influenced the hydrological state of a large waterbody such as Lake Karakul, while annual precipitation amount and inflows remained fairly constant. KW - climate KW - biomarker KW - geochemistry KW - modelling KW - paleoclimate KW - hydrology Y1 - 2019 U6 - https://doi.org/10.1029/2019GL085202 SN - 0094-8276 SN - 1944-8007 VL - 46 IS - 23 SP - 13972 EP - 13983 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Markowska, Monika A1 - Fohlmeister, Jens Bernd A1 - Treble, Pauline C. A1 - Baker, Andy A1 - Andersen, Martin S. A1 - Hua, Quan T1 - Modelling the C-14 bomb-pulse in young speleothems using a soil carbon continuum model JF - Geochimica et cosmochimica acta : journal of the Geochemical Society and the Meteoritical Society N2 - The ‘bomb-pulse’ method is a chronological approach to further constrain the age of speleothems that grew between 1950 CE – present. Establishing dependable chronological constraints is crucial for modern calibration studies of speleothems to instrumental climate records, which provides the basis for paleoclimate interpretations. However, a large unknown is how 14C is transferred from the atmosphere to any individual speleothem owing to the site-specific residence times of organic matter above cave systems. Here, we employ the bomb-pulse method to build chronologies from 14C measurements in combination with a new unsaturated zone C model which considers C decomposition as a continuum, to better understand unsaturated zone 14C dynamics. The bomb-pulse curves of eight speleothems from southern Australia in three contrasting climatic regions; the semi-arid Wellington Caves site, the mediterranean Golgotha Cave site and the montane Yarrangobilly Caves site, are investigated. Overall, the modelled 14C bomb-pulse curves produce excellent fits with measured 14C speleothem data (r2 = 0.82–0.99). The C modelling reveals that unsaturated zone C is predominately young at the semi-arid site, with a weighted-mean residence time of 32 years and that tree root respiration is likely an important source of vadose CO2. At the montane site, ∼39% of C is young (<1 years), but the weighted-mean C ages are older (145–220 years). The mediterranean site has very little contribution from young C (<12%: 0–1 years), with weighted-mean ages between 157 and 245 years, likely due to greater adsorption of organic matter in the upper vadose zone during matrix flow, and remobilisation of C from young syngenetic karst. New end members for low speleothem Dead Carbon Proportion (DCP) are identified (2.19% and 1.65%, respectively) for Australian montane and semi-arid zone speleothems, where oversupply of modern CO2 in the vadose zone leads to lower DCP. It is also demonstrated that DCP can be quite variable over small time scales, that processes may be difficult to untangle and a constant DCP assumption is likely invalid. DCP variability over time is mainly controlled by the changes vadose zone CO2, where vegetation regeneration, wild-fires and karst hydrology play an important role. KW - Carbon 14 KW - speleothems KW - vadose zone KW - modelling Y1 - 2019 U6 - https://doi.org/10.1016/j.gca.2019.04.029 SN - 0016-7037 SN - 1872-9533 VL - 261 SP - 342 EP - 367 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Saltikoff, Elena A1 - Friedrich, Katja A1 - Soderholm, Joshua A1 - Lengfeld, Katharina A1 - Nelson, Brian A1 - Becker, Andreas A1 - Hollmann, Rainer A1 - Urban, Bernard A1 - Heistermann, Maik A1 - Tassone, Caterina T1 - An Overview of Using Weather Radar for Climatological Studies: Successes, Challenges, and Potential JF - Bulletin of the American Meteorological Society N2 - Weather radars have been widely used to detect and quantify precipitation and nowcast severe weather for more than 50 years. Operational weather radars generate huge three-dimensional datasets that can accumulate to terabytes per day. So it is essential to review what can be done with existing vast amounts of data, and how we should manage the present datasets for the future climatologists. All weather radars provide the reflectivity factor, and this is the main parameter to be archived. Saving reflectivity as volumetric data in the original spherical coordinates allows for studies of the three-dimensional structure of precipitation, which can be applied to understand a number of processes, for example, analyzing hail or thunderstorm modes. Doppler velocity and polarimetric moments also have numerous applications for climate studies, for example, quality improvement of reflectivity and rain rate retrievals, and for interrogating microphysical and dynamical processes. However, observational data alone are not useful if they are not accompanied by sufficient metadata. Since the lifetime of a radar ranges between 10 and 20 years, instruments are typically replaced or upgraded during climatologically relevant time periods. As a result, present metadata often do not apply to past data. This paper outlines the work of the Radar Task Team set by the Atmospheric Observation Panel for Climate (AOPC) and summarizes results from a recent survey on the existence and availability of long time series. We also provide recommendations for archiving current and future data and examples of climatological studies in which radar data have already been used. Y1 - 2019 U6 - https://doi.org/10.1175/BAMS-D-18-0166.1 SN - 0003-0007 SN - 1520-0477 VL - 100 IS - 9 SP - 1739 EP - 1751 PB - American Meteorological Soc. CY - Boston ER - TY - JOUR A1 - Hudson, Paul A1 - Botzen, W. J. Wouter A1 - Aerts, Jeroen C. J. H. T1 - Flood insurance arrangements in the European Union for future flood risk under climate and socioeconomic change JF - Global environmental change : human and policy dimensions N2 - Flood risk will increase in many areas around the world due to climate change and increase in economic exposure. This implies that adequate flood insurance schemes are needed to adapt to increasing flood risk and to minimise welfare losses for households in flood-prone areas. Flood insurance markets may need reform to offer sufficient and affordable financial protection and incentives for risk reduction. Here, we present the results of a study that aims to evaluate the ability of flood insurance arrangements in Europe to cope with trends in flood risk, using criteria that encompass common elements of the policy debate on flood insurance reform. We show that the average risk-based flood insurance premium could double between 2015 and 2055 in the absence of more risk reduction by households exposed to flooding. We show that part of the expected future increase in flood risk could be limited by flood insurance mechanisms that better incentivise risk reduction by policyholders, which lowers vulnerability. The affordability of flood insurance can be improved by introducing the key features of public-private partnerships (PPPs), which include public reinsurance, limited premium cross-subsidisation between low- and high-risk households, and incentives for policyholder-level risk reduction. These findings were evaluated in a comprehensive sensitivity analysis and support ongoing reforms in Europe and abroad that move towards risk-based premiums and link insurance with risk reduction, strengthen purchase requirements, and engage in multi-stakeholder partnerships. KW - Climate change adaptation KW - Flood risk KW - Insurance KW - Public-private partnerships KW - Risk reduction Y1 - 2019 U6 - https://doi.org/10.1016/j.gloenvcha.2019.101966 SN - 0959-3780 SN - 1872-9495 VL - 58 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Kornher, Lukas A1 - Kalkuhl, Matthias T1 - The gains of coordination - When does regional cooperation for food security make sense? JF - Global Food Security - AGRICULTURE POLICY ECONOMICS AND ENVIRONMENT N2 - With the onset of the global food crisis, the discussion about the use and misuse of agricultural market interventions regained academic attention. As a result of economies of scale, centralized policy implementation at the regional level has the potential to reduce the budgetary costs of policies. Borrowing from the literature on international unions and international policy coordination, we develop a conceptual framework to analyze when regional policy implementation makes sense. This is the case whenever spill-overs from centralization are large and policy preferences, driven by country-specific characteristics, are homogeneous. Subsequently, we examine the advantageousness of centralized policy implementation for the West African region regarding the most common food security policies. We show that centralization of trade policies and emergency food reserves is beneficial, while buffer stocks, safety net policies, and producer support policies should be implemented at the national level. KW - Food security KW - Regional cooperation KW - West Africa KW - International unions Y1 - 2019 U6 - https://doi.org/10.1016/j.gfs.2019.09.004 SN - 2211-9124 VL - 22 SP - 37 EP - 45 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Margirier, Audrey A1 - Braun, Jean A1 - Gautheron, Cecile A1 - Carcaillet, Julien A1 - Schwartz, Stephane A1 - Jamme, Rosella Pinna A1 - Stanley, Jessica T1 - Climate control on Early Cenozoic denudation of the Namibian margin as deduced from new thermochronological constraints JF - Earth & planetary science letters N2 - The processes that control long term landscape evolution in continental interiors and, in particular, along passive margins such as in southern Africa, are still the subject of much debate (e.g. Braun, 2018). Although today the Namibian margin is characterized by an arid climate, it has experienced climatic fluctuations during the Cenozoic and, yet, to date no study has documented the potential role of climate on its erosion history. In western Namibia, the Brandberg Massif, an erosional remnant or inselberg, provides a good opportunity to document the Cenozoic denudation history of the margin using the relationship between rock cooling or exhumation ages and their elevation. Here we provide new apatite (UThSm)/He dates on the Brandberg Inselberg that range from 151 +/- 12 to 30 +/- 2 Ma. Combined with existing apatite fission track data, they yield new constraints on the denudation history of the margin. These data document two main cooling phases since continental break-up 130 Myr ago, a rapid one (similar to 10 degrees C/Myr) following break-up and a slower one (similar to 12 degrees C/Myr) between 65 and 35 Ma. We interpret them respectively to be related to escarpment erosion following rifting and continental break-up and as a phase of enhanced denudation during the Early Eocene Climatic Optimum. We propose that during the Early Eocene Climatic Optimum chemical weathering was important and contributed significantly to the denudation of the Namibian margin and the formation of a pediplain around the Brandberg and enhanced valley incision within the massif. Additionally, aridification of the region since 35 Ma has resulted in negligible denudation rates since that time. (C) 2019 Elsevier B.V. All rights reserved. KW - climate KW - Early Eocene Climatic Optimum KW - apatite (U-Th-Sm)/He thermochronology KW - denudation KW - weathering KW - Namibian passive margin Y1 - 2019 U6 - https://doi.org/10.1016/j.epsl.2019.115779 SN - 0012-821X SN - 1385-013X VL - 527 PB - Elsevier CY - Amsterdam ER -