The thermal field across the Alpine orogen and its forelands and the relation to seismicity

2020 ◽  
Author(s):  
Cameron Spooner ◽  
Magdalena Scheck-Wenderoth ◽  
Mauro Cacace ◽  
Hans-Jürgen Götze ◽  
Elco Luijendijk
Keyword(s):  
Thermal Field ◽  
Structural Model ◽  
Seismogenic Zone ◽  
Thermally Activated ◽  
Brittle Ductile Transition ◽  
Region Temperature ◽  
Crustal Strength ◽  
Modelling Techniques ◽  
The Alps ◽  
Shed Light

<p>The Alpine orogen and its forelands comprise a multitude of crustal blocks from different tectonic providences and different physical properties. This implies that the thermal configuration of the lithosphere would also be expected to vary significantly throughout the region. Temperature is a key controlling factor for rock strength via thermally activated creep and it exerts a first order influence on the depth of the brittle-ductile transition zone, the lower bound to the seismogenic zone and the spatial distribution of seismicity. Here we present new results from INTEGRATE, a project in the DFG priority program Mountain Building in 4 Dimensions, as part of the AlpArray initiative, which aims to gain a better understanding of the structure, temperature and rheology of the crust and the uppermost mantle beneath the Alps and their forelands using multiple 3D modelling techniques. The overall goal is to test different hypotheses on the configuration of the lithosphere and its relation to the distribution of deformation and related seismicity in the Alpine region. We build on previous work of a 3D density differentiated structural model of the region that is consistent with deep seismic data and gravity, to calculate the 3D conductive steady state thermal field of the Alps and their forelands. The model is unique in using different thermal parameters for different tectonic domains and is validated with a dataset of wellbore temperatures from across the region. Comparing recorded seismicity to the calculated thermal field we find a systematic clustering of the deep seismic activity that correlates with different isotherms within individual crustal blocks, reflecting the presence of different dominant lithologies. These inferred lithologies in conjunction with the calculated temperatures and the previous 3D density-structural model of the region, can be used to shed light on the lateral changes in crustal strength within the Alps and their forelands, helping to explain the observed patterns of deformation.  </p>

scholarly journals Migrating bats cross top of Europe

2016 ◽  
Author(s):  
Peter E Zingg ◽  
Fabio Bontadina
Keyword(s):  
High Altitude ◽  
Climatic Conditions ◽  
Swiss Alps ◽  
Research Station ◽  
Long Distance ◽  
Tadarida Brasiliensis ◽  
The Alps ◽  
Shed Light ◽  
The Way

Bats have evolved migration to escape unfavourable climatic conditions. However, their migratory flyways and the way how they surmount geographical barriers are still unknown. The Jungfraujoch in the Swiss Alps is a mountain covered in permafrost (3460m ASL), known colloquially as the “Top of Europe”. Using broadband ultrasound recorders, we tested the occurrence of bats at the high altitude research station. In 36 nights, we recorded 268 bat call sequences of 8 species, including all European long-distance migrant bats. Since no feeding buzzes were recorded, we assume the bats were on transit. This is the first evidence to show that migrating bats can fly at unprecedented altitudes to cross the Alps. This feat outperforms the spectacular behaviour of the high altitude foraging bat Tadarida brasiliensis. Our findings shed light on the bats’ migratory flyways and demonstrate that the field of aeroecology can still uncover unexpected perspectives on the behaviour of bats.

scholarly journals Crustal Thermal Structure and Exhumation Rates in the Southern Alps Near the Central Alpine Fault, New Zealand

2021 ◽  
Author(s):  
K Michailos ◽  
Rupert Sutherland ◽  
John Townend ◽  
Martha Savage
Keyword(s):  
New Zealand ◽  
Thermal Structure ◽  
Hanging Wall ◽  
Southern Alps ◽  
Seismogenic Zone ◽  
Fixed Temperature ◽  
Alpine Fault ◽  
Brittle Ductile Transition ◽  
Orogenic Uplift ◽  
Exhumation Rates

© 2020. American Geophysical Union. All Rights Reserved. We investigate orogenic uplift rates and the thermal structure of the crust in the hanging wall of the Alpine Fault, New Zealand, using the hypocenters of 7,719 earthquakes that occurred in the central Southern Alps between late 2008 and early 2017, and previously published thermochronological data. We assume that the base of the seismogenic zone corresponds to a brittle-ductile transition at some fixed temperature, which we estimate by fitting the combined thermochronological data and distribution of seismicity using a multi-1-D approach. We find that exhumation rates vary from 1 to 8 mm/yr, with maximum values observed in the area of highest topography near Aoraki/Mount Cook, a finding consistent with previous geologic and geodetic analyses. We estimate the temperature of the brittle-ductile transition beneath the Southern Alps to be 410–430°C, which is higher than expected for Alpine Fault rocks whose bulk lithology is likely dominated by quartz. The high estimated temperatures at the base of the seismogenic zone likely reflect the unmodeled effects of high fluid pressures or strain rates.

scholarly journals The Deep Structure and Rheology of a Plate Boundary-Scale Shear Zone: Constraints from an Exhumed Caledonian Shear Zone, NW Scotland

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Alexander D. J. Lusk ◽  
John P. Platt
Keyword(s):  
Shear Stress ◽  
Internal Structure ◽  
Shear Zone ◽  
Deep Structure ◽  
Plate Boundary ◽  
Seismogenic Zone ◽  
Differential Stress ◽  
Peak Shear Stress ◽  
Thrust Zone ◽  
Crustal Strength

Abstract Below the seismogenic zone, faults are expressed as zones of distributed ductile strain in which minerals deform chiefly by crystal plastic and diffusional processes. We present a case study from the Caledonian frontal thrust system in northwest Scotland to better constrain the geometry, internal structure, and rheology of a major zone of reverse-sense shear below the brittle-to-ductile transition (BDT). Rocks now exposed at the surface preserve a range of shear zone conditions reflecting progressive exhumation of the shear zone during deformation. Field-based measurements of structural distance normal to the Moine Thrust Zone, which marks the approximate base of the shear zone, together with microstructural observations of active slip systems and the mechanisms of deformation and recrystallization in quartz, are paired with quantitative estimates of differential stress, deformation temperature, and pressure. These are used to reconstruct the internal structure and geometry of the Scandian shear zone from ~10 to 20 km depth. We document a shear zone that localizes upwards from a thickness of >2.5 km to <200 m with temperature ranging from ~450–350°C and differential stress from 15–225 MPa. We use estimates of deformation conditions in conjunction with independently calculated strain rates to compare between experimentally derived constitutive relationships and conditions observed in naturally-deformed rocks. Lastly, pressure and converted shear stress are used to construct a crustal strength profile through this contractional orogen. We calculate a peak shear stress of ~130 MPa in the shallowest rocks which were deformed at the BDT, decreasing to <10 MPa at depths of ~20 km. Our results are broadly consistent with previous studies which find that the BDT is the strongest region of the crust.

INVESTIGATION OF THE DYNAMICS OF THE ELASTIC-MASS SYSTEM OF THE MOBILE HEARTH OF AN ELECTRIC KILN FOR FIRING THERMALLY ACTIVATED MATERIALS

2020 ◽  
Author(s):  
Anatoliy Nizhegorodov ◽  
Aleksey Gavrilin ◽  
Boris Moyzes ◽  
Georgiy Odnokopylov ◽  
G. Izmalov
Keyword(s):  
Elastic Element ◽  
Thermal Field ◽  
Bulk Material ◽  
Excitation Frequency ◽  
Heating System ◽  
Strong Nonlinearity ◽  
Mass System ◽  
Friction Forces ◽  
Thermally Activated ◽  
Horizontal Arrangement

In article results of research of properties elastic element platform furnace with a movable hearth, the analytical model of motion, characterized by sloping skeletal curve of its amplitude-frequency characteristics. The study of the dynamics of elastic-mass system of the platform with unilateral elastic element in the form of a flattened elastic ring that provides her a strong nonlinearity, it is confirmed that the system does not symmetrical oscillation with peak acceleration values of 5.17 and 1.17 m/S2, corresponding to the extreme provisions of the different platform and four and a half times. It is shown that the horizontal arrangement of the movable hearth of the furnace significantly reduces the sensitivity of its vibrations to changes in the excitation frequency, spring stiffness, friction forces, and other factors that change due to the influence of high temperature and external environmental factors. The effect of vibration transport of bulk material along the horizontal surface of the mobile hearth of the furnace platform in the thermal field of its heating system is confirmed.

Highly stressed lower crust: Evidence from dry pseudotachylytes in granulites, Lofoten, Norway

2020 ◽  
Author(s):  
Kristina G. Dunkel ◽  
Xin Zhong ◽  
Luiz F. G. Morales ◽  
Bjørn Jamtveit
Keyword(s):  
Lower Crust ◽  
Electron Backscatter Diffraction ◽  
Alkali Feldspar ◽  
Mineralogical Composition ◽  
Plastic Instability ◽  
Wall Rock ◽  
Seismogenic Zone ◽  
Hydrous Minerals ◽  
Brittle Ductile Transition ◽  
Lower Crustal

<p>Due to the high confining pressures in the lower crust, the generating mechanisms of lower crustal earthquakes, occurring below the standard seismogenic zone, are puzzling. Their investigation is difficult because the records of such earthquakes, pseudotachylytes, are typically reacted and/or deformed. Here we describe exceptionally pristine pseudotachylytes in lower crustal granulites from the Lofoten Vesterålen Archipelago, Norway. The pseudotachylytes have essentially the same mineralogical composition as their host (plagioclase, alkali feldspar, orthopyroxene) and contain microstructures indicative of rapid cooling (microlites, spherulites, ‘cauliflower’ garnet). Neither the wall rock nor the pseudotachylytes themselves contain hydrous minerals, and no mylonites are associated with the pseudotachylytes. This excludes the most commonly suggested weakening mechanisms that may cause earthquakes below the brittle-ductile transition: dehydration- or reaction-induced embrittlement, plastic instability, thermal runaway, and downward propagation of seismic rupture from shallow faults into their deeper ductile extensions. Hence, we suggest that transient stress pulses caused by shallower earthquakes are the most likely explanation for the occurrence of fossil earthquakes in the analysed rocks from Lofoten.</p><p>Earthquakes are short events, but their effects on the tectonic and metamorphic development of their host can be long-lasting. The initial deformation features related to seismic events, which potentially determine these effects, are often overprinted by metamorphism driven by fluids infiltrating the rock along the seismic fault. Because of the anhydrous conditions in the present case, those structures are preserved. The wall rocks to the investigated pseudotachylytes appear undamaged in optical and backscatter electron observation; however, cathodoluminescence imaging of feldspar and quartz reveals healed fractures and alteration zones. Those areas are further investigated with electron backscatter diffraction and transmission electron microscopy to better understand the microstructural and chemical changes during and after the seismic event.</p>

scholarly journals Multidimensional Skills, Sorting, and Human Capital Accumulation

2020 ◽  
Vol 110 (8) ◽  
pp. 2328-2376 ◽  
Author(s):  
Jeremy Lise ◽  
Fabien Postel-Vinay
Keyword(s):  
Job Search ◽  
Capital Accumulation ◽  
Structural Model ◽  
Initial Conditions ◽  
Model Combining ◽  
Combining Data ◽  
Sources Of Variation ◽  
Skill Requirements ◽  
Skill Dimensions ◽  
Shed Light

We construct a structural model of on-the-job search in which workers differ in skills along several dimensions and sort themselves into jobs with heterogeneous skill requirements along those same dimensions. Skills are accumulated when used, and depreciate when not used. We estimate the model combining data from O*NET with the NLSY79. We use the model to shed light on the origins and costs of mismatch along heterogeneous skill dimensions. We highlight the deficiencies of relying on a unidimensional model of skill when decomposing the sources of variation in the value of lifetime output between initial conditions and career shocks. (JEL J24, J41, J64)

scholarly journals Migrating bats cross top of Europe

2016 ◽  
Author(s):  
Peter E Zingg ◽  
Fabio Bontadina
Keyword(s):  
High Altitude ◽  
Climatic Conditions ◽  
Swiss Alps ◽  
Research Station ◽  
Long Distance ◽  
Tadarida Brasiliensis ◽  
The Alps ◽  
Shed Light ◽  
The Way

Bats have evolved migration to escape unfavourable climatic conditions. However, their migratory flyways and the way how they surmount geographical barriers are still unknown. The Jungfraujoch in the Swiss Alps is a mountain covered in permafrost (3460m ASL), known colloquially as the “Top of Europe”. Using broadband ultrasound recorders, we tested the occurrence of bats at the high altitude research station. In 36 nights, we recorded 268 bat call sequences of 8 species, including all European long-distance migrant bats. Since no feeding buzzes were recorded, we assume the bats were on transit. This is the first evidence to show that migrating bats can fly at unprecedented altitudes to cross the Alps. This feat outperforms the spectacular behaviour of the high altitude foraging bat Tadarida brasiliensis. Our findings shed light on the bats’ migratory flyways and demonstrate that the field of aeroecology can still uncover unexpected perspectives on the behaviour of bats.

scholarly journals Crustal Thermal Structure and Exhumation Rates in the Southern Alps Near the Central Alpine Fault, New Zealand

2021 ◽  
Author(s):  
K Michailos ◽  
Rupert Sutherland ◽  
John Townend ◽  
Martha Savage
Keyword(s):  
New Zealand ◽  
Thermal Structure ◽  
Hanging Wall ◽  
Southern Alps ◽  
Seismogenic Zone ◽  
Fixed Temperature ◽  
Alpine Fault ◽  
Brittle Ductile Transition ◽  
Orogenic Uplift ◽  
Exhumation Rates

© 2020. American Geophysical Union. All Rights Reserved. We investigate orogenic uplift rates and the thermal structure of the crust in the hanging wall of the Alpine Fault, New Zealand, using the hypocenters of 7,719 earthquakes that occurred in the central Southern Alps between late 2008 and early 2017, and previously published thermochronological data. We assume that the base of the seismogenic zone corresponds to a brittle-ductile transition at some fixed temperature, which we estimate by fitting the combined thermochronological data and distribution of seismicity using a multi-1-D approach. We find that exhumation rates vary from 1 to 8 mm/yr, with maximum values observed in the area of highest topography near Aoraki/Mount Cook, a finding consistent with previous geologic and geodetic analyses. We estimate the temperature of the brittle-ductile transition beneath the Southern Alps to be 410–430°C, which is higher than expected for Alpine Fault rocks whose bulk lithology is likely dominated by quartz. The high estimated temperatures at the base of the seismogenic zone likely reflect the unmodeled effects of high fluid pressures or strain rates.

scholarly journals Modeling Hsp70/Hsp40 interaction by multi-scale molecular simulations and co-evolutionary sequence analysis

2016 ◽  
Author(s):  
Duccio Malinverni ◽  
Alfredo Jost Lopez ◽  
Paolo De Los Rios ◽  
Gerhard Hummer ◽  
Alessandro Barducci
Keyword(s):  
Sequence Analysis ◽  
Structural Model ◽  
Molecular Simulations ◽  
Evolutionary Sequence ◽  
Multi Scale ◽  
Atomistic Models ◽  
Structural Details ◽  
Shock Proteins ◽  
Interaction Surface ◽  
Shed Light

AbstractThe interaction between the Heat Shock Proteins 70 and 40 is at the core of the ATPase regulation of the chaperone machinery that maintains protein homeostasis. However, the structural details of this fundamental interaction are still elusive and contrasting models have been proposed for the transient Hsp70/Hsp40 complexes. Here we combine molecular simulations based on both coarsegrained and atomistic models with co-evolutionary sequence analysis to shed light on this problem by focusing on the bacterial DnaK/DnaJ system. The integration of these complementary approaches resulted into a novel structural model that rationalizes previous experimental observations. We identify an evolutionary-conserved interaction surface formed by helix II of the DnaJ J-domain and a groove on lobe IIA of the DnaK nucleotide binding domain, involving the inter-domain linker.

scholarly journals Deformation along the roof of a fossil subduction interface in the transition zone below seismogenic coupling: The Austroalpine case and new insights from the Malenco Massif (Central Alps)

Geosphere ◽  
2020 ◽  
Vol 16 (2) ◽  
pp. 510-532
Author(s):  
Paraskevi Io Ioannidi ◽  
Samuel Angiboust ◽  
Onno Oncken ◽  
Philippe Agard ◽  
Johannes Glodny ◽  
...  
Keyword(s):  
Transition Zone ◽  
Shear Zones ◽  
White Mica ◽  
Seismogenic Zone ◽  
Central Alps ◽  
Massif Central ◽  
Brittle Ductile Transition ◽  
Wide Range ◽  
Deformation Processes ◽  
Transition Field

Abstract A network of fossil subduction plate interfaces preserved in the Central Alps (Val Malenco, N Italy) is herein used as a proxy to study deformation processes related to subduction and subsequent underplating of continental slices (in particular the Margna and Sella nappes) at depths reported to in the former brittle-ductile transition. Field observations, microfabrics, and mapping revealed a network of shear zones comprising mostly mylonites and schists but also rare foliated cataclasites. These shear zones are either located at the contacts of the two nappes or within the boundaries of the Sella unit. Microprobe results point to two different white mica generations, with higher-pressure (Si-rich) phengites rimming lower-pressure (Si-poor) phengites. Garnet is locally observed overgrowing resorbed pre-Alpine cores. Pressure-temperature estimates based on pseudosection modeling point to peak burial deformation conditions of ∼0.9 GPa and 350–400 °C, at ∼30 km depth. Rb/Sr geochronology on marbles deformed during the Alpine event yields an age of 48.9 ± 0.9 Ma, whereas due to incomplete recrystallization, a wide range of both Rb/Sr and 40Ar/39Ar apparent ages is obtained from deformed orthogneisses and micaschists embracing 87–44 Ma. Based on our pressure-temperature, structural and geochronological observations, the studied shear zones last equilibrated at depths downdip of the seismogenic zone in an active subduction zone setting. We integrate these new results in the frame of previous studies on other segments of the same Alpine paleosubduction interface, and we propose that this system of shear zones represents deformation conditions along the subduction interface(s) in the transition zone below the seismogenic zone during active subduction.

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