Relict rockglaciers are distinctive indicators of past permafrost occurrence. Their lower limit is attributed to a former mean annual air temperature (MAAT) of below −2 °C. This study provides a ...comprehensive dataset of 34 10Be exposure ages from boulders along two complex series of relict rockglaciers, called Tandl rockglaciers and Norbert rockglaciers (Carinthia, Austria). The lowest Tandl rockglacier complex stabilised around 14 ka at an elevation of 1350 m a.s.l., the lowest Norbert rockglaciers (1580 and 1730 m a.s.l.) stabilised around 15.7 ka. Additionally, in both study sites the low elevation relict rockglaciers interacted with glacial deposits of the local pre-Bølling glaciers (Gschnitz stadial glacier). Temperature lowering based on our data of the Gschnitz rockglaciers ranges between 6.3 and 4.5 °C compared to modern MAAT. The cross-cutting relationships of the rockglaciers and the glacial deposits together with the exposure ages of the rockglaciers, indicate that these rockglaciers, and therewith also permafrost, developed shortly after or even simultaneously with retreat of the Gschnitz stadial glaciers. This is the first permafrost formation in the Alpine areas after the retreat of the (warm-based) Last Glacial Maximum glaciers. The Tandl and Norbert rockglacier lobes located at higher elevations, up to about 2300 m a.s.l., finally stabilised in the early Holocene; ages of several dated lobes lie between 12-10 ka. At this time, which corresponds to the Egesen stadial (Younger Dryas) cold phase, rockglaciers and glaciers co-existed. From the lowest position of the Egesen rockglacier lobe at the Tandl site (1700 m a.s.l.), a temperature lowering for the Egesen stadial of −4.6 °C was calculated. This study highlights the potential of relict rockglacier deposits as an independent paleoclimate archive and their usefulness for reconstruction of past permafrost development and distribution in high mountain areas when they can be placed in a temporal framework.
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•34 new 10Be exposure ages from boulders along two series of relict rockglaciers.•Direct dating of first permafrost development after the LGM.•Relict rockglaciers as viable paleoclimate archive.•MAAT offset determined for Lateglacial.
This article presents an overview of findings on the varieties of spoken Slovenian in Austrian Carinthia, focusing in particular on the changes perceived by researchers in the last two decades and on ...contemporary speech practices. Findings by other researchers are built upon with the results of biographical interviews conducted with seven students of Slovenian at the University of Klagenfurt. Three topics are at the forefront: the attitude toward the local dialect, the use of standard Slovenian variety, and speech accommodation in groups.
Lake sediments are increasingly used to reconstruct recurrence intervals of large earthquakes - a prerequisite for the establishment of accurate seismic hazard models - because they can record strong ...seismic shaking as mass-transport deposits (MTDs), turbidites or sediment deformations and often reach back several thousands of years. To derive quantitative information on paleo-earthquake size, the sedimentary imprints need to be thoroughly calibrated with independent information on seismic shaking strength. A few calibration studies proposed scaling relationships between the shaking strength of historical earthquakes and the type and size of lacustrine sedimentary imprints. Due to incomprehensive lacustrine mapping or an insufficient record of documented earthquakes, however, rigorous testing of these scaling relationships is lacking. Here, we study the sedimentary infill of the past ∼800 years in Wörthersee and Millstättersee, two large lakes in the Eastern Alps (Carinthia, Austria). These lakes have experienced five well-documented historical earthquakes with local seismic intensities ranging from V – IX (EMS-98 scale). We trace the sedimentary signatures (MTDs and turbidites) of these earthquakes based on a vast dataset of multibeam bathymetry, reflection seismic profiles and numerous precisely dated sediment cores. Seismic intensities as low as V½ are recorded as turbidites originating from deltaic slopes, while hemipelagic slopes can fail from intensities of VI onwards. In Wörthersee, earthquake-recording thresholds are highly dependent on the specific core locations due to local variations in slope characteristics (composition, length, and gradient) and transport distance to the core site. This highlights the potential for establishing multi-threshold paleoseismic records based on multiple coring sites in a single basin. In both lakes, exponential size-scaling relationships are inferred between seismic intensity and i) number or volume of mass-transport deposits and ii) the cumulative thickness of turbidites. Moreover, the relative turbidite presence increases linearly with seismic intensity, confirming the results from a previous study in Chilean lakes. Application of the obtained size-scaling relationships on the first major earthquake documented for Austria (1201 CE) suggests a magnitude of ∼6.4 and an epicentre close to Millstätter See. This demonstrates that lake paleoseismology is a powerful tool to obtain quantitative information on the seismic intensity distribution of paleo-earthquakes.
•Calibration of earthquake imprints in lakes with historical intensity data.•Seismic intensity thresholds are site-specific and range from V½ to VIII½.•Scaling relationships between landslides/turbidites and seismic intensity exist.•Sedimentation rate is a key parameter controlling earthquake sensitivity of lakes.
Spectacular geomorphic evidence of recent tectonic activity and three potentially strong prehistoric earthquakes were discovered in Obir Caves in the Karawanken Mountains. This paper presents active ...fault structures, geomorphic features, and the age constraints attributed to particular seismotectonic events. The 1976 Mw 6.7 Friuli earthquake about 100 km from Obir Caves caused only local speleothem damage. The 100 km hypocentral distance enabled attenuation of the seismic waves so speleothem damage due to stalagmite resonance frequency was dampened. The documented dripstone column damage was rather caused by its sudden shortening due to passing elastic S-waves with estimated 3.5 (+8.2/−1.5) mm PGD amplitudes. At least three distinct seismotectonic events in the Late Pleistocene and Early to Middle Holocene were constrained by radiometric dating. The 40.6 cm sinistral fault slip occurred between 41.8 ± 1.3 ka and 18.7 ± 0.4 ka ago, the 2.6 cm dextral oblique reverse fault slip happened between 10.73 ± 0.23 and 8.61 ± 0.15 ka ago, and another speleothem damage event took place between 6.28 ± 0.24 ka and 5.7 ± 1.2 ka ago. These events were most probably accompanied by distinct destructive to very destructive paleoearthquakes with local intensities ranging from VIII to X on the ESI 2007 scale, significant rock weakening, and forming the large deep-seated gravitational slope deformation on the southeastern mountain slopes adjacent to Obir Caves.
•We discovered evidence of three paleoearthquakes in the Eastern Alps.•Speleothem damage and fault offsets indicate intensities VIII to X (ESI 2007).•They occurred in the Late Pleistocene and Early to Middle Holocene.•1976 Mw 6.7 Friuli EQ caused dripstone column damage by its co-seismic shortening.
Described as “the age of extremes” by historian Eric Hobsbawm, the 20
century was defined by heavily-contested borders and identities in Central Europe: politically, culturally, socially, and ...intellectually. With the end of World War I, communities found themselves in new nation- states, and the politics of assimilation and relations between minorities and their kinstates created tensions that continue to reverberate today. Using the Slovene minority in Austria as a case study, the article provides insight into two international projects that involve civil society actors in the field of memory politics and young people and their attitudes towards history and minorities. In drawing lessons from these initiatives dealing with troubled pasts to counteract current forms of exclusive identity politics, the article proposes that effective minority protection depends on a conductive social environment that allows for the reflection of opposing narratives stemming from ethnic conflict and acknowledges diversity as enrichment.
Trace element concentrations in quartz were determined from two major LCT pegmatite occurrences in Europe to test the applicability of quartz as a pathfinder mineral for Li mineralized pegmatites. ...The Wolfsberg spodumene pegmatite deposit and pegmatites throughout the wider Austroalpine Unit (Austria), and the Moylisha spodumene pegmatite deposit (SE Ireland), present two distinctly different geological histories. Spodumene pegmatites at Wolfsberg are associated with late Permian lithospheric extension that formed the Austroalpine Unit Pegmatite Province spanning the Eastern Alps. They were metamorphosed at up to eclogite-facies conditions during the Alpine orogeny. Contrastingly, the simple and spodumene pegmatites at Moylisha form a late Silurian to early Devonian NE-SW-striking pegmatite belt that intruded the East Carlow Deformation Zone along the SE margin of the late Caledonian S-type Leinster Batholith. All analyzed pegmatites contain assemblages including K-feldspar, albite, quartz, muscovite ± spodumene. LA-ICP-MS analysis shows quartz from spodumene pegmatites in both regions is distinguishable from that in simple pegmatites by higher concentrations of Al, Li, Ge and B, whereas simple pegmatite quartz contains higher Ti. Increasing concentrations of Al, Li and Ge and decreasing Ti in quartz from simple pegmatites (to leucogranites in the Austroalpine Unit) to spodumene pegmatites reflects increasing degree of fractionation, resulting from either magmatic differentiation or separately generated but increasingly fractionated melts. Chemical profiles through individual spodumene pegmatite bodies show relatively little chemical variation, consistent with Li saturation through most of their crystallization history. Principal component analysis of quartz data shows that high Ge, Be and B concentrations characterize quartz in pegmatites from the Austroalpine Unit whereas high Al and Li concentrations characterize quartz in pegmatites from Moylisha. Concentrations of >100 μgg−1 Al and >30 μgg−1 Li in pegmatite quartz represent an important threshold for potential spodumene mineralization, which may also be indicated by host rocks (e.g., mica schist) metasomatized by fluids expelled by pegmatites during emplacement and/or crystallization and generating a chemical halo. Retention of pegmatite chemical signatures at Wolfsberg supports the robustness of quartz as an effective pathfinder tool for Li mineralized pegmatites in regions that have been affected by high-pressure metamorphism. LA-ICP-MS of quartz in soil and stream sediments may also be a useful pathfinder in pegmatite provinces where Li-rich quartz is not too diluted by other quartz.
•Quartz trace elements determined for LCT pegmatites at Wolfsberg and Moylisha.•Respective Ge-Be-B and Al-Li signatures in Wolfsberg and Moylisha pegmatite quartz.•Increasing Al, Li, Ge/decreasing Ti in quartz from simple to spodumene pegmatites.•>100 μgg−1 Al and > 30 μgg−1 Li in pegmatite quartz indicative of Li mineralization.
Methanogenic burst in the end-Permian carbon cycle Rothman, Daniel H.; Fournier, Gregory P.; French, Katherine L. ...
Proceedings of the National Academy of Sciences - PNAS,
04/2014, Letnik:
111, Številka:
15
Journal Article
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The end-Permian extinction is associated with a mysterious disruption to Earth’s carbon cycle. Here we identify causal mechanisms via three observations. First, we show that geochemical signals ...indicate superexponential growth of the marine inorganic carbon reservoir, coincident with the extinction and consistent with the expansion of a new microbial metabolic pathway. Second, we show that the efficient acetoclastic pathway in Methanosarcina emerged at a time statistically indistinguishable from the extinction. Finally, we show that nickel concentrations in South China sediments increased sharply at the extinction, probably as a consequence of massive Siberian volcanism, enabling a methanogenic expansion by removal of nickel limitation. Collectively, these results are consistent with the instigation of Earth’s greatest mass extinction by a specific microbial innovation.
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