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.
Methanogenic burst in the end-Permian carbon cycle Rothman, Daniel H.; Fournier, Gregory P.; French, Katherine L. ...
Proceedings of the National Academy of Sciences,
04/2014, Letnik:
111, Številka:
15
Journal Article
Recenzirano
Odprti dostop
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.
The south-western part of the Carinthian (or Frög) group of the Early Iron Age, located between the valley of the Gail/Zilja and Villach/Beljak (Rosegg/Rožek), bordered the Veneti in northern Italy ...and the Sveta Lucija group in western Slovenia. The relationships with these neighbours, alongside the trade in amber from the Baltic Sea, salt from Hallstatt and Dürrnberg, as well as iron and lead from the Alps, brought to the eastern Alpine areas not only foreign luxury goods, but also people and ideas. One communication with the southern neighbours led across the Predel/Predil Pass, evidence of which can be found in a pin with a moulded neck from Napoleonwiese at Villach that has parallels in Tolmin. Further along the Soča/Isonzo, contacts between Caput Adriae and Carinthia/Kärnten may be reflected in the pottery with lead appliqués. Evidence of such contacts and circulations of ideas can also be seen in the use and development of the Unec type pendants, in the boat fibulae (Kahnfibeln) of the Villach type and the Paularo type of east Alpine animal-headed fibulae (ostalpine Tierkopffibel) that indicate a common artisanal tradition in Posočje and Kärnten in the 5th/4th century BC, as well as in the commonalities that the tumulus from Schmeißer Boden at Gurina shows with the tumuli in Mel near Belluno.
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