TY - JOUR A1 - Schildgen, Taylor F. A1 - van der Beek, Peter A. A1 - D'Arcy, Mitch A1 - Roda-Boluda, Duna N. A1 - Orr, Elizabeth N. A1 - Wittmann, Hella T1 - Quantifying drainage-divide migration from orographic rainfall over geologic timescales BT - Sierra de Aconquija, southern Central Andes JF - Earth & planetary science letters N2 - Drainage-divide migration, controlled by rock-uplift and rainfall patterns, may play a major role in the geomorphic evolution of mountain ranges. However, divide-migration rates over geologic timescales have only been estimated by theoretical studies and remain empirically poorly constrained. Geomorphological evidence suggests that the Sierra de Aconquija, on the eastern side of the southern Central Andes, northwest Argentina, is undergoing active westward drainage-divide migration. The mountain range has been subjected to steep rock trajectories and pronounced orographic rainfall for the last several million years, presenting an ideal setting for using low-temperature thermochronometric data to explore its topographic evolution. We perform three-dimensional thermal-kinematic modeling of previously published thermochronometric data spanning the windward and leeward sides of the range to explore the most likely structural and topographic evolution of the range. We find that the data can be explained by scenarios involving drainage-divide migration alone, or by scenarios that also involve changes in the structures that have accommodated deformation through time. By combining new Be-10-derived catchment-average denudation rates with geomorphic constraints on probable fault activity, we conclude that the evolution of the range was likely dominated by west-vergent faulting on a high-angle reverse fault underlying the range, together with westward drainage-divide migration at a rate of several km per million years. Our findings place new constraints on the magnitudes and rates of drainage-divide migration in real landscapes, quantify the effects of orographic rainfall and erosion on the topographic evolution of a mountain range, and highlight the importance of considering drainage-divide migration when interpreting thermochronometer age patterns. KW - drainage-divide migration KW - landscape evolution KW - orographic rainfall KW - thermochronology KW - cosmogenic nuclides KW - Central Andes Y1 - 2022 U6 - https://doi.org/10.1016/j.epsl.2021.117345 SN - 0012-821X SN - 1385-013X VL - 579 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ortiz, Gustavo A1 - Saez, Mauro A1 - Alvarado, Patricia A1 - Rivas, Carolina A1 - García, Víctor Hugo A1 - Alonso, Ricardo A1 - Zullo, Fernando Morales T1 - Seismotectonic characterization of the 1948 (M-W 6.9) Anta earthquake Santa Barbara System, central Andes broken foreland of northwestern Argentina JF - Journal of South American earth sciences N2 - The region of the Andean back-arc of northwestern Argentina has been struck by several magnitude >= 6 crustal earthquakes since the first historically recorded event in 1692. One of these events corresponds to the Anta earthquake on 25 August 1948, with epicenter in the Santa Barbara System causing three deaths and severe damage in Salta and Jujuy provinces with maximum Modified Mercalli seismic intensities (MMI) of IX. We collected and digitized analog seismograms of this earthquake from worldwide seismic observatories in order to perform first-motion analysis and modeling of long-period teleseismic P-waveforms. Our results indicate a simple seismic source of M0 = 2.85 x 1019 N m consistent with a moment magnitude Mw = 6.9. We have also tested for the focal depth determining a shallow source at 8 km with a reverse focal mechanism solution with a minor dextral strike-slip component (strike 20 degrees, dip 30 degrees, rake 120 degrees) from the best fit of waveforms. Using magnitude size empirical relationships, the comparison of the obtained Mw 6.9 magnitude value and the ca. 10,000 km2 area of MMI >= IX from our seismic intensity map, which was obtained from newspaper and many historical reports, indicates a rupture length of 42 +/- 8 km for the Anta earthquake. We show our results in a 3D geological model around the epicentral area, which integrates modern seismicity, geological data, and information of a previously studied east-west cross section located a few kilometers south of the 1948 epicenter. The integration of all available information provides evidence of the re-activation of the Pie de la Sierra del Gallo fault during the 1948 Mw 6.9 shallow earthquake; this thrust fault bounds the Santa Barbara System along its western foothill. KW - Active tectonics KW - Analog historical seismograms KW - Andean back-arc; KW - Thick-skinned tectonics KW - Central Andes Y1 - 2022 U6 - https://doi.org/10.1016/j.jsames.2022.103822 SN - 0895-9811 SN - 1873-0647 VL - 116 PB - Elsevier CY - Oxford ER - TY - THES A1 - Antonoglou, Nikolaos T1 - GNSS-based remote sensing: Innovative observation of key hydrological parameters in the Central Andes T1 - GNSS-basierte Fernerkundung: Innovative Beobachtung der wichtigsten hydrologischen Parameter in den zentralen Anden N2 - The Central Andean region is characterized by diverse climate zones with sharp transitions between them. In this work, the area of interest is the South-Central Andes in northwestern Argentina that borders with Bolivia and Chile. The focus is the observation of soil moisture and water vapour with Global Navigation Satellite System (GNSS) remote-sensing methodologies. Because of the rapid temporal and spatial variations of water vapour and moisture circulations, monitoring this part of the hydrological cycle is crucial for understanding the mechanisms that control the local climate. Moreover, GNSS-based techniques have previously shown high potential and are appropriate for further investigation. This study includes both logistic-organization effort and data analysis. As for the prior, three GNSS ground stations were installed in remote locations in northwestern Argentina to acquire observations, where there was no availability of third-party data. The methodological development for the observation of the climate variables of soil moisture and water vapour is independent and relies on different approaches. The soil-moisture estimation with GNSS reflectometry is an approximation that has demonstrated promising results, but it has yet to be operationally employed. Thus, a more advanced algorithm that exploits more observations from multiple satellite constellations was developed using data from two pilot stations in Germany. Additionally, this algorithm was slightly modified and used in a sea-level measurement campaign. Although the objective of this application is not related to monitoring hydrological parameters, its methodology is based on the same principles and helps to evaluate the core algorithm. On the other hand, water-vapour monitoring with GNSS observations is a well-established technique that is utilized operationally. Hence, the scope of this study is conducting a meteorological analysis by examining the along-the-zenith air-moisture levels and introducing indices related to the azimuthal gradient. The results of the experiments indicate higher-quality soil moisture observations with the new algorithm. Furthermore, the analysis using the stations in northwestern Argentina illustrates the limits of this technology because of varying soil conditions and shows future research directions. The water-vapour analysis points out the strong influence of the topography on atmospheric moisture circulation and rainfall generation. Moreover, the GNSS time series allows for the identification of seasonal signatures, and the azimuthal-gradient indices permit the detection of main circulation pathways. N2 - Die Zentralanden sind eine Region, in der verschiedene Klimazonen nur durch kurze Übergänge gekennzeichnet sind. Der geographische Schwerpunkt dieser Arbeit liegt in den südlichen Zentralanden im Grenzgebiet zwischen Argentinien, Bolivien und Chile, und der wissenschaftliche Schwerpunkt ist in der Überwachung der Bodenfeuchtigkeit und des Wasserdampfs mit Fernerkundungsmethoden des Globales Navigationssatellitensystem (Global Navigation Satellite System - GNSS) angesiedelt. Wegen der raschen zeitlichen und räumlichen Schwankungen des Wasserdampfs und den damit häufig verbundenen Niederschlägen und der Feuchtigkeitszirkulation ist die Beobachtung dieses Teils des hydrologischen Zyklus von entscheidender Bedeutung für das Verständnis des lokalen Klimas. Darüber hinaus haben GNSS-gestützte Techniken in anderen Studien bereits ein hohes Potenzial gezeigt, erfordern aber in einigen Bereichen weitere Untersuchungen. Diese Studie umfasst sowohl logistischen Aufwand als auch Datenanalyse. Dazu wurden drei GNSS-Bodenstationen in abgelegenen Orten im Nordwesten Argentiniens installiert, um Beobachtungen zu sammeln, da dort keine externen Daten verfügbar waren. Die methodische Entwicklung für die Beobachtung der Klimavariablen Bodenfeuchtigkeit und Wasserdampfs ist unabhängig voneinander. Die Messung der Bodenfeuchte mit Hilfe der GNSS-Reflektometrie ist eine Annäherung, die vielversprechende Ergebnisse erbracht hat, aber bisher noch nicht operationell eingesetzt wurde. Daher wurde ein fortschrittlicherer Algorithmus entwickelt, der Beobachtungen von mehreren Satellitenkonstellationen nutzt und unter anderem Daten von zwei Pilotstationen in Deutschland verwendet. Außerdem wurde dieser Algorithmus leicht modifiziert und in einer Meeresspiegelmesskampagne eingesetzt. Obwohl diese Andwendung nicht direkt mit der Überwachung hydrologischer Parameter zusammenhängt, basiert die Methodik auf denselben Prinzipien und hilft bei der Bewertung des entwickelten Algorithmus. Auf der anderen Seite ist die Überwachung des Wasserdampfs mit GNSS-Beobachtungen eine anerkannte Technik, die in der Praxis bereits seit mehreren Jahren eingesetzt wird. Diese Studie befasst sich daher mit der Durchführung einer meteorologischen Analyse der Luftfeuchtigkeitswerte entlang des Zenits und der Entwicklung von klimatischen Indizes, die sich auf den azimutalen Gradienten beziehen. Die Ergebnisse der Experimente zeigen, dass die Qualität der Bodenfeuchtebeobachtungen mit dem neuen Algorithmus vielversprechend und besser sind. Darüber hinaus zeigt die Analyse anhand der Stationen im nordwesten Argentiniens die Grenzen dieser Technologie aufgrund der sehr unterschiedlichen Bodenbedingungen auf und gibt mögliche zukünftige Forschungsrichtung an. Die Wasserdampfanalyse verdeutlicht den Einfluss der Topographie auf die Luftfeuchtigkeit und der Regenmenge. Außerdem ermöglichen die GNSS-Zeitreihen die Identifizierung der jahreszeitlichen Signaturen, und Messungen der azimutal Gradienten erlauben die Erkennung der wichtigsten Zirkulationswege. KW - remote sensing KW - GNSS KW - GPS KW - water vapour KW - soil moisture KW - Central Andes KW - zentrale Anden KW - globales Navigationssatellitensystem KW - globales Positionsbestimmungssystem KW - Fernerkundung KW - Bodenfeuchtigkeit KW - Wasserdampf Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-628256 ER - TY - JOUR A1 - Liu, Sibiao A1 - Sobolev, Stephan A1 - Babeyko, Andrey A1 - Pons, Michaël T1 - Controls of the foreland deformation pattern in the orogen-foreland shortening system BT - constraints from high-resolution geodynamic models JF - Tectonics N2 - Controls on the deformation pattern (shortening mode and tectonic style) of orogenic forelands during lithospheric shortening remain poorly understood. Here, we use high-resolution 2D thermomechanical models to demonstrate that orogenic crustal thickness and foreland lithospheric thickness significantly control the shortening mode in the foreland. Pure-shear shortening occurs when the orogenic crust is not thicker than the foreland crust or thick, but the foreland lithosphere is thin (<70-80 km, as in the Puna foreland case). Conversely, simple-shear shortening, characterized by foreland underthrusting beneath the orogen, arises when the orogenic crust is much thicker. This thickened crust results in high gravitational potential energy in the orogen, which triggers the migration of deformation to the foreland under further shortening. Our models present fully thick-skinned, fully thin-skinned, and intermediate tectonic styles in the foreland. The first tectonics forms in a pure-shear shortening mode whereas the others require a simple-shear mode and the presence of thick (>similar to 4 km) sediments that are mechanically weak (friction coefficient 95th percentile) along an E-W traverse across the southern Central Andes using rain-gauge and high-resolution gridded datasets (CPC-uni and TRMM 3B42 V7). We generated different climate indices and made three key observations: (1) an increase of the annual rainfall has occurred at the transition between low (< 0.5 km) and intermediate (0.5-3 km) elevations between 1950 and 2014. Also, rainfall increases during the wet season and, to a lesser degree, decreases during the dry season. Increasing trends in annual total amounts characterize the period 1979-2014 in the arid, high-elevation southern Andean Plateau, whereas trend reversals with decreasing annual total amounts were found at low elevations. (2) For all analyzed periods, we observed small or no changes in the median values of the rainfall-frequency distribution, but significant trends with intensification or attenuation in the 95th percentile. (3) In the southern Andean Plateau, extreme rainfall events exhibit trends towards increasing magnitude and, to a lesser degree, frequency during the wet season, at least since 1979. Our analysis revealed that low (< 0.5 km), intermediate (0.5-3 km), and high-elevation (> 3 km) areas respond differently to changing climate conditions, and the transition zone between low and intermediate elevations is characterized by the most significant changes. KW - Extreme rainfall KW - South American Monsoon System KW - Central Andes KW - Quantile regression KW - Rain gauges KW - CPC-uni KW - TRMM KW - Orographic barrier Y1 - 2017 U6 - https://doi.org/10.1007/s00382-016-3127-2 SN - 0930-7575 SN - 1432-0894 VL - 48 SP - 1049 EP - 1067 PB - Springer CY - New York ER - TY - JOUR A1 - Araya Vargas, Jaime Andrés A1 - Meqbel, Naser M. A1 - Ritter, Oliver A1 - Brasse, H. A1 - Weckmann, Ute A1 - Yanez, Gonzalo A1 - Godoy, B. T1 - Fluid Distribution in the Central Andes Subduction Zone Imaged With Magnetotellurics JF - Journal of geophysical research : Solid earth N2 - We present a model of the electrical resistivity structure of the lithosphere in the Central Andes between 20 degrees and 24 degrees S from 3-D inversion of 56 long-period magnetotelluric sites. Our model shows a complex resistivity structure with significant variability parallel and perpendicular to the trench direction. The continental forearc is characterized mainly by high electrical resistivity (>1,000m), suggesting overall low volumes of fluids. However, low resistivity zones (LRZs, <5m) were found in the continental forearc below areas where major trench-parallel faults systems intersect NW-SE transverse faults. Forearc LRZs indicate circulation and accumulation of fluids in highly permeable fault zones. The continental crust along the arc shows three distinctive resistivity domains, which coincide with segmentation in the distribution of volcanoes. The northern domain (20 degrees-20.5 degrees S) is characterized by resistivities >1,000m and the absence of active volcanism, suggesting the presence of a low-permeability block in the continental crust. The central domain (20.5 degrees-23 degrees S) exhibits a number of LRZs at varying depths, indicating different levels of a magmatic plumbing system. The southern domain (23 degrees-24 degrees S) is characterized by resistivities >1,000m, suggesting the absence of large magma reservoirs below the volcanic chain at crustal depths. Magma reservoirs located below the base of the crust or in the backarc may fed active volcanism in the southern domain. In the subcontinental mantle, the model exhibits LRZs in the forearc mantle wedge and above clusters of intermediate-depth seismicity, likely related to fluids produced by serpentinization of the mantle and eclogitization of the slab, respectively. KW - Subduction Zone KW - Central Andes KW - Magnetotellurics KW - Seismotectonic segmentation KW - Fluid processes Y1 - 2019 U6 - https://doi.org/10.1029/2018JB016933 SN - 2169-9313 SN - 2169-9356 VL - 124 IS - 4 SP - 4017 EP - 4034 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Ibarra, Federico A1 - Liu, Sibiao A1 - Meeßen, Christian A1 - Prezzi, Claudia Beatriz A1 - Bott, Judith A1 - Scheck-Wenderoth, Magdalena A1 - Sobolev, Stephan Vladimir A1 - Strecker, Manfred T1 - 3D data-derived lithospheric structure of the Central Andes and its implications for deformation: Insights from gravity and geodynamic modelling JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - We present a new three-dimensional density model of the Central Andes characterizing the structure and composition of the lithosphere together with a geodynamic simulation subjected to continental intraplate shortening. The principal aim of this study is to assess the link between heterogeneities in the lithosphere and different deformation patterns and styles along the orogen-foreland system of the Central Andes. First, we performed a 3D integration of new geological and geophysical data with previous models through forward modelling of Bouguer anomalies. Subsequently, a geodynamic model was set-up and parametrized from the previously obtained 3D structure and composition. We do not find a unambigous correlation between the resulting density configuration and terrane boundaries proposed by other authors. Our models reproduce the observed Bouguer anomaly and deformation patterns in the foreland. We find that thin-skinned deformation in the Subandean fold-and thrust belt is controlled by a thick sedimentary layer and coeval underthrusting of thin crust of the foreland beneath the thick crust of the Andean Plateau. In the adjacent thick-skinned deformation province of the inverted Cretaceous extensional Santa Barbara System sedimentary strata are much thinner and crustal thickness transitions from greater values in the Andean to a more reduced thickness in the foreland. Our results show that deformation processes occur where the highest gradients of lithospheric strength are present between the orogen and the foreland, thus suggesting a spatial correlation between deformation and lithospheric strength. KW - Central Andes KW - Lithospheric structure KW - Gravity modelling KW - Geodynamic modelling KW - Deformation Y1 - 2019 U6 - https://doi.org/10.1016/j.tecto.2019.06.025 SN - 0040-1951 SN - 1879-3266 VL - 766 SP - 453 EP - 468 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Liu, Sibiao T1 - Controls of foreland-deformation patterns in the orogen-foreland shortening system N2 - The Andean Plateau (Altiplano-Puna Plateau) of the southern Central Andes is the second-highest orogenic plateau on our planet after Tibet. The Andean Plateau and its foreland exhibit a pronounced segmentation from north to south regarding the style and magnitude of deformation. In the Altiplano (northern segment), more than 300 km of tectonic shortening has been recorded, which started during the Eocene. A well-developed thin-skinned thrust wedge located at the eastern flank of the plateau (Subandes) indicates a simple-shear shortening mode. In contrast, the Puna (southern segment) records approximately half of the shortening of the Altiplano - and the shortening started later. The tectonic style in the Puna foreland switches to a thick-skinned mode, which is related to pure-shear shortening. In this study, carried out in the framework of the StRATEGy project, high-resolution 2D thermomechanical models were developed to systematically investigate controls of deformation patterns in the orogen-foreland pair. The 2D and 3D models were subsequently applied to study the evolution of foreland deformation and surface topography in the Altiplano-Puna Plateau. The models demonstrate that three principal factors control the foreland-deformation patterns: (i) strength differences in the upper lithosphere between the orogen and its foreland, rather than a strength difference in the entire lithosphere; (ii) gravitational potential energy of the orogen (GPE) controlled by crustal and lithospheric thicknesses, and (iii) the strength and thickness of foreland-basin sediments. The high-resolution 2D models are constrained by observations and successfully reproduce deformation structures and surface topography of different segments of the Altiplano-Puna plateau and its foreland. The developed 3D models confirm these results and suggest that a relatively high shortening rate in the Altiplano foreland (Subandean foreland fold-and-thrust belt) is due to simple-shear shortening facilitated by thick and mechanically weak sediments, a process which requires a much lower driving force than the pure-shear shortening deformation mode in the adjacent broken foreland of the Puna, where these thick sedimentary basin fills are absent. Lower shortening rate in the Puna foreland is likely accommodated in the forearc by the slab retreat. N2 - Das Andenplateau (Altiplano-Puna-Plateau) in den südlichen Zentralanden ist nach Tibet das zweithöchste orogene Plateau auf unserem Planeten. Dieses Plateau und sein Vorland weisen eine ausgeprägte Segmentierung von Nord nach Süd hinsichtlich Art und Ausmaß der Verformung auf. Im Altiplano (nördliches Segment) wird seit der im Eozän stattfindenden Deformation mehr als 300 km tektonische Verkürzung dokumentiert. Ein gut entwickelter sedimentärer Schubkeil bzw. Vorland-Überschiebungsgürtel (Subandin) an der Ostflanke des Plateaus (thin-skinned foreland deformation) deutet in dieser Region des Vorlandes auf Prozesse einfacher Scherung hin (simple-shear modus). Im Gegensatz dazu weist die Puna (südliches Plateausegment) ungefähr die Hälfte der Verkürzung des Altiplano auf - und die Verkürzung begann später. Außerdem geht der tektonische Stil im Puna-Vorland zu einem zerbrochenen Vorland mit Kristallinblöcken (thick-skinned foreland) über, der mit der Verkürzung durch reine Scherung (pure-shear modus) erklärt werden kann. In dieser Studie, die im Rahmen des StRATEGy-Projekts durchgeführt wurde, wurden hochauflösende thermomechanische 2D-Modelle entwickelt, um systematisch die Kontrolle von Verformungsmustern im Orogen-Vorland-Paar zu untersuchen. Die 2D- und 3D-Modelle wurden anschließend angewendet, um die Entwicklung der Vorlanddeformation und der Oberflächentopographie im Altiplano-Puna-Plateau zu verstehen. Die Modelle zeigen, dass drei Hauptfaktoren die Deformationsmuster des Vorlandes steuern: (i) Festigkeitsunterschiede in der oberen Lithosphäre zwischen dem Orogen und seinem Vorland - und nicht Festigkeitsunterschiede in der gesamten Lithosphäre; (ii) die gravitationsbezogene potentielle Energie des Orogens (GPE), die durch die Krusten- und Lithosphärenmächtigkeit gesteuert wird und (iii) die Festigkeit sowie Mächtigkeiten der Vorlandbeckensedimente. Die hochauflösenden 2D-Modelle sind auf tatsächliche Daten aus Beobachtungen beschränkt und reproduzieren erfolgreich Deformationsstrukturen sowie die topographischen Verhältnisse der verschiedenen Segmente des Altiplano-Puna-Plateaus und seines Vorlandes. Die entwickelten 3D-Modelle bestätigen diese Ergebnisse und legen nahe, dass die relativ hohe Verkürzungsrate im Altiplano-Vorland (Subandin) bei den vorhandenen mächtigen Sedimentabfolgen geringer mechanischer Festigkeit weniger Kraftaufwand erfordert als die Deformation des Puna-Vorlandes, wo diese Sedimente weitgehend fehlen. Die geringeren Verkürzungsbeträge im Puna-Vorland werden wahrscheinlich durch das Zurückweichen der Subduktionszone im Forearc-Bereich ausgeglichen. KW - geodynamics KW - numerical modeling KW - Central Andes KW - foreland deformation KW - geophysics KW - Geodynamik KW - numerische Modellierung KW - Zentralanden KW - Vorlanddeformation KW - Geophysik Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-445730 ER - TY - JOUR A1 - Castino, Fabiana A1 - Bookhagen, Bodo A1 - Strecker, Manfred T1 - Oscillations and trends of river discharge in the southern Central Andes and linkages with climate variability JF - Journal of hydrology N2 - This study analyzes the discharge variability of small to medium drainage basins (10(2)-10(4) km(2)) in the southern Central Andes of NW Argentina. The Hilbert-Huang Transform (HHT) was applied to evaluate non-stationary oscillatory modes of variability and trends, based on four time series of monthly normalized discharge anomaly between 1940 and 2015. Statistically significant trends reveal increasing discharge during the past decades and document an intensification of the hydrological cycle during this period. An Ensemble Empirical Mode Decomposition (EEMD) analysis revealed that discharge variability in this region can be best described by five quasi-periodic statistically significant oscillatory modes, with mean periods varying from 1 to 20 y. Moreover, we show that discharge variability is most likely linked to the phases of the Pacific Decadal Oscillation (PDO) at multi-decadal timescales (similar to 20 y) and, to a lesser degree, to the Tropical South Atlantic SST anomaly (TSA) variability at shorter timescales (similar to 2-5 y). Previous studies highlighted a rapid increase in discharge in the southern Central Andes during the 1970s, inferred to have been associated with the global 1976-77 climate shift. Our results suggest that the rapid discharge increase in the NW Argentine Andes coincides with the periodic enhancement of discharge, which is mainly linked to a negative to positive transition of the PDO phase and TSA variability associated with a long-term increasing trend. We therefore suggest that variations in discharge in this region are largely driven by both natural variability and the effects of global climate change. We furthermore posit that the links between atmospheric and hydrologic processes result from a combination of forcings that operate on different spatiotemporal scales. (C) 2017 Elsevier B.V. All rights reserved. KW - River discharge KW - Central Andes KW - Empirical Mode Decomposition KW - PDO KW - Climate variability KW - Global climate change Y1 - 2017 U6 - https://doi.org/10.1016/j.jhydrol.2017.10.001 SN - 0022-1694 SN - 1879-2707 VL - 555 SP - 108 EP - 124 PB - Elsevier CY - Amsterdam ER -