Alfred Gruber

The morphological and geological conditions for the formation of rock glaciers in Alpine environments seem to be clear according to our present knowledge (BARSCH, 1996; HAEBERLI et al. 2006). All known examples derive from porous more or less coarse grained sedimentary bodies, either from moraines or, in most cases, from talus fans. In the latter case the debris accumulation originates overwhelmingly from physical weathering, rock falls or rock avalanches in proximity to rockwalls. However, in the course of geological mapping in the crystalline areas of Eastern and Northern Tyrol (Schober Gruppe, Tuxer Alpen) we found an additional setting. Some relict rock glaciers occur directly at the bulging toe of bedrock slopes, which had been affected by deep-seated gravitational slope deformations (REITNER, 2003; GRUBER, 2005). Furthermore rock glaciers are also present in ridge-top depressions and similar graben-like features that originated from gravitational processes in jointed bedrock. ...

Major gravitational slope deformations are widely disseminated in the Dolomite Mountains (NE-Italy), one of the world 0 s most conspicuous landscapes and part of the UNESCO world heritage list. Because of their unique geological composition the Dolomites provide a natural laboratory where nearly all kind of mass wasting processes, in all dimensions, can be investigated. Simplified there are thick, rigid carbonatic successions (Triassic-Jurassic) resting on and interfingering with relatively weak successions of shallow marine clastic and of pelagic sediments. In some areas even volcanic successions and crystalline basement rocks are outcropped. Hugh rockslides and long run-out rock avalanches are limited to the carbonates and volcanic rocks. The superposition of Middle and Upper Triassic reefs, showing brittle deformation behaviour, above weak successions of evaporites, clays and marls, characterised by ductile deformation behaviour, leads to a classical “hard on soft” situation. The...

The geological mapping of the Western Dolomites was mainly carried out within the framework of the project Geological Base Map South Tyrol, Sedimentary Part in the years 1995 to 2003. The main focus of the project was on the bedrock and structural geology, less on the quaternary geological mapping. The mapping of quaternary deposits was therefore carried out partly according to lithofacial, partly according to lithogenetic, and often according to geomorphological criteria using aerial photography interpretations. This applies in particular to the widespread landslides, which in the main valleys have frequently reworked the sediments and altered the morphology of the Würmian Late Glacial Maximum (LGM) and the Würmian Lateglacial. For the 2nd edition of the Geological Map of the Western Dolomites, the quarternary deposits and the landforms were revised by the interpretation of aerial photographs and laser scan images, field observations and consultation of new research results. The st...

Zusammenfassung Neue struktur-und quartärgeologische Geländedaten vom Angerberg im Unterinntal (Tirol, Österreich), insbesondere die Durchteufung des «Butterbichls» belegen eine der mächtigsten fossilen Felsgleitungen Tirols. Ältere tektonische Interpretationen ( ...

In the Dolomites, the transition from the post-Variscan to the Alpine orogen cycle generally takes place in a domain of lithospheric stretching, which is recorded in several plate tectonically controlled megacycles in the sediment sequences. Early Permian and Middle Triassic magmatism are associated with this development. In contrast to the "post-Variscan" magmatism, however, the Middle Triassic magmatism gives rise to numerous discussions due to its orogenic chemistry in the extensional setting of the Dolomites. A new analysis of the tectonostratigraphic development now revealed an interpretation of the processes that differs from the general opinion. Within the general extensional development in the Permo-Mesozoic there are four distinct unconformities caused by compressive or transpressive tectonic intervals.

The Dolomite Mountains are known for their spectacular seismic scale outcrops showing Triassic carbonate platforms and build-ups preserved with their clinoforms and slope facies in primary transition to adjacent basinal areas. The juxtaposition of Middle and Upper Triassic reefs and basins is preserved due to the lack of strong tectonic deformation and is strengthened by erosion to form the extraordinary landscape as seen today. Since the outstanding studies of Richthofen (1860) and Mojsisovics (1879), who correctly recognized the primary geometries of the buildups (“Überguss-Schichtung”) in transition to the basins, the Dolomites are the type area for heteropic facies developments. Bosellini (1984) presented the first modern synthesis of the depositional geometries of the build-ups. Regional sequence stratigraphy was firmly established with the revision of the chronostratigraphic framework by Brack & Rieber (1993), De Zanche et al., (1993) and Mietto & Manfrin (1995). In addition, ...

The morphological and geological conditions for the formation of rock glaciers in Alpine environments seem to be clear according to our present knowledge (BARSCH, 1996; HAEBERLI et al. 2006). All known examples derive from porous more or less coarse grained sedimentary bodies, either from moraines or, in most cases, from talus fans. In the latter case the debris accumulation originates

In 3D-Modellen wird versucht, die wahre Geometrie von Strukturen darzustellen. Da bei 3D-Modellen im 3D-Raum gearbeitet wird, entfallen theoretisch Verschnitteffekte, die bei der Projektion auf 2D-Bildebenen zur Verzerrung führen. Die Grundlage von 3D-Modellen ist allerdings immer noch die geologische Kartierung, sodass diesen Verzerrungseffekten nicht ganz ausgewichen werden kann. Die Erfassung von Strukturen im 3D-Raum erfolgt durch ihre Verschnittlinie mit dem Höhenmodell, aus der die 3D-Struktur berechnet werden kann. Damit hängt die Genauigkeit der 3D-Struktur stark von der Genauigkeit des Höhenmodells ab. Das Höhenmodell, mit dem hier gearbeitet wurde, beruht auf verbesserten SRTM-Daten mit einer Auflösung von 1“. Die Genauigkeit nach der Projektion im österreichischen Gauß-Krüger Netz beträgt etwa 40 m und erlaubt deshalb nur eine ungefähre Konstruktion von Strukturen im Raum. 3D Modelle haben einen großen Nachteil: sie sind in 2D-Abbildungen unübersichtlich. Deswegen wird hi...

The Northern Calcareous Alps (NCA) are a fold-and-thrust belt built by Permomesozoic rocks. It was affected by Early Jurassic rifting prior to Late Creatceous stacking of thrust sheets. The inversion of Jurassic basins resulted in complex fold structures. One of the enigmatic areas is the Achensee region, where a major kilometric W-E trending anticline-syncline system (Montschein-anticline, Karwendel-syncline) is offset to the north east of lake Achensee (Guffert-anticline, Thiersee syncline). The anticlines and synclines west and east of the transfer zone are recumbent, but no thrust is visible. In the transfer zone, the axis of the anticline curves to a N-S orientation (Unnutz anticline), whereas the syncline evolves to a thrust with 5km offset in E-W cross section (Achental thrust) that superimposes Triassic on Cretaceous rocks. The 3D-model in this low-budget project was constructed to understand the kinematic evolution of the fold and thrust system. Input data were: (1) a tecto...

Zusammenfassung Neue struktur-und quartärgeologische Geländedaten vom Angerberg im Unterinntal (Tirol, Österreich), insbesondere die Durchteufung des «Butterbichls» belegen eine der mächtigsten fossilen Felsgleitungen Tirols. Ältere tektonische Interpretationen ( ...