Showing papers in "Swiss Journal of Geosciences in 2010"
TL;DR: In this article, an overview of the areal distribution and the geometry of overdeepened troughs in the Alps and their foreland, and summarises the present knowledge of the age and potential processes that may have caused deep erosion.
Abstract: Overdeepened valleys and basins are commonly found below the present landscape surface in areas that were affected by Quaternary glaciations. Overdeepened troughs and their sedimentary fillings are important in applied geology, for example, for geotechnics of deep foundations and tunnelling, groundwater resource management, and radioactive waste disposal. This publication is an overview of the areal distribution and the geometry of overdeepened troughs in the Alps and their foreland, and summarises the present knowledge of the age and potential processes that may have caused deep erosion. It is shown that overdeepened features within the Alps concur mainly with tectonic structures and/or weak lithologies as well as with Pleistocene ice confluence and partly also diffluence situations. In the foreland, overdeepening is found as elongated buried valleys, mainly oriented in the direction of former ice flow, and glacially scoured basins in the ablation area of glaciers. Some buried deeply incised valleys were generated by fluvial down-cutting during the Messinian crisis but this mechanism of formation applies only for the southern side of the Alps. Lithostratigraphic records and dating evidence reveal that overdeepened valleys were repeatedly occupied and excavated by glaciers during past glaciations. However, the age of the original formation of (non-Messinian) overdeepened structures remains unknown. The mechanisms causing overdeepening also remain unidentified and it can only be speculated that pressurised meltwater played an important role in this context.
138 citations
TL;DR: A computer aided design analysis using high-resolution laser scans of the bones of the stegosaur Kentrosaurus aethiopicus Hennig as mentioned in this paper from the Late Jurassic Tendaguru Formation indicates that in the habitual walking pose the forelimbs were probably held erect, and that strong humeral flexion and abduction mainly occurred in a defensive stance.
Abstract: A computer aided design analysis using high-resolution laser scans of the bones of the stegosaur Kentrosaurus aethiopicus Hennig
1915 from the Late Jurassic Tendaguru Formation indicates that in the habitual walking pose the forelimbs were probably held erect, and that strong humeral flexion and abduction mainly occurred in a defensive stance. Rapid gaits with unsupported phases could not be used. The neck allowed sufficient lateral flexion to guarantee good sight in all directions including posteriorly. The tail covered an arch of roughly 180° and had sufficient range to be used as a weapon. Possibly, the animal could accomplish tail blows against specific targets in sight. Also, a tripodal pose is suggested to have been possible, roughly doubling the maximum vertical feeding height of Kentrosaurus.
61 citations
TL;DR: In Stegosaurus the potential thermoregulatory role of the plates may have been greater than in other thyreophorans, by virtue of their extensive external and internal vascularity, their large size, thin cross-sections above the plate base, dorsal position, and alternating arrangement.
Abstract: X-ray computed tomography and petrographic thin sectioning were used to study internal features of the plates of the thyreophoran dinosaur Stegosaurus and the osteoderms of Alligator. Infrared thermographic imaging of basking caimans was used to examine possible differential blood flow to osteoderms and other parts of the skin. Multiple large openings in the Stegosaurus plate base lead to a linear, mesiodistally oriented vestibule, which in turn apically sends off multiply branching “pipes”. The pipes are best developed in the basal half of the plate, and communicate with cancellous regions (some of which presumably were vascular spaces) throughout the plate interior. Some internal vascular features also connect with vascular pits and grooves on the plate surface. Alligator osteoderms show a similar internal vascularity. In crocodylians, the osteoderms serve as armor and help to stiffen the back for terrestrial locomotion, but their vascularity enables them to be used as sources of calcium for egg shelling, as sites of lactate sequestration, and possibly for heat exchange with the external environment, as suggested by our infrared thermographic imaging of basking caimans. Thyreophoran osteoderms presumably had multiple functions as well. In Stegosaurus the potential thermoregulatory role of the plates may have been greater than in other thyreophorans, by virtue of their extensive external and internal vascularity, their large size, thin cross-sections above the plate base, dorsal position, and alternating arrangement.
55 citations
TL;DR: In this article, a first-order appraisal based solely on geological criteria collated from the literature is presented, which shows that the Swiss Molasse Basin (SMB) and the adjacent Folded Jura are the only realms of the country where CO2 could conceivably be stored in saline aquifers.
Abstract: Possibilities to sequester anthropogenic CO2 in deep geological formations are being investigated worldwide, but the potential within Switzerland has not yet been evaluated. This study presents a first-order appraisal based solely on geological criteria collated from the literature. The Swiss Molasse Basin (SMB) and the adjacent Folded Jura are the only realms of the country where CO2 could conceivably be stored in saline aquifers. Evaluation of geological criteria at the basin-wide scale shows that the SMB–Jura has moderate potential (score of 0.6 on a scale from 0 to 1) when compared to basins elsewhere. At the intrabasinal scale, inspection of the stratigraphy reveals four regional candidate aquifers that are sealed by suitable caprocks: top Basement plus basal Mesozoic sandstones, all sealed by the Anhydrite Group; Upper Muschelkalk sealed by the Gipskeuper; Hauptrogenstein sealed by the Effinger Member, and Upper Malm plus Lower Cretaceous sealed by the Lower Freshwater Molasse. Nine geological criteria are defined to evaluate the storage potential of these and other smaller scale candidates. A numerical scoring and weighting scheme allows the criteria to be assessed simultaneously, permitting the storage potential to be depicted using the 0–1 scale in contoured maps. Approximately 5,000 km2 of the central SMB exhibits potentials between 0.6 and 0.96. The Fribourg–Olten–Luzern area is the most favoured owing to the presence of several sealed aquifers within the preferred 800–2,500 m depth interval, and to its low seismicity, low geothermal gradient, low fault density, and long groundwater residence times. Smaller areas with good potential lie between Zurich and St. Gallen. In contrast, western Switzerland, the Jura and the southern SMB have markedly poorer potential. Considering only the portions of the aquifers with potential above 0.6, the theoretical, effective storage capacity of the basin is estimated to be 2,680 million tonnes of CO2.
52 citations
TL;DR: In this article, a high-resolution micropalaeontological study combined with geochemical and sedimentological analyses was performed on the Tiefengraben, Schlossgraben and Eiberg sections (Austrian Alps) in order to characterize sea-surface carbonate production during the end-Triassic crisis.
Abstract: A high-resolution micropalaeontological study, combined with geochemical and sedimentological analyses was performed on the Tiefengraben, Schlossgraben and Eiberg sections (Austrian Alps) in order to characterize sea-surface carbonate production during the end-Triassic crisis. At the end-Rhaetian, the dominant calcareous nannofossil Prinsiosphaera triassica shows a decrease in abundance and size and this is correlated with a increase in δ18O and a gradual decline in δ13Ccarb values. Simultaneously, benthic foraminiferal assemblages show a decrease in diversity and abundance of calcareous taxa and a dominance of infaunal agglutinated taxa. The smaller size of calcareous nannofossils disturbed the vertical export balance of the biological carbon pump towards the sea-bottom, resulting in changes in feeding strategies within the benthic foraminiferal assemblages from deposit feeders to detritus feeders and bacterial scavengers. These micropalaeontological data combined with geochemical proxies suggest that changes in seawater chemistry and/or cooling episodes might have occurred in the latest Triassic, leading to a marked decrease of carbonate production. This in turn culminated in the quasi-absence of calcareous nannofossils and benthic foraminifers in the latest Triassic. The aftermath (latest Triassic earliest Jurassic) was characterised by abundance peaks of “disaster” epifaunal agglutinated foraminifera Trochammina on the sea-floor. Central Atlantic Magmatic Province (CAMP) paroxysmal activity, superimposed on a major worldwide regressive phase, is assumed to be responsible for a deterioration in marine palaeoenvironments. CAMP sulfuric emissions might have been the trigger for cooling episodes and seawater acidification leading to disturbance of the surface carbonate production at the very end-Triassic.
50 citations
TL;DR: A new phylogeny, which includes all valid stegosaurian taxa, largely agrees with previous studies and shows the European Dacentrurinae was sister taxon to Stegosaurus.
Abstract: The first partial skeleton of a stegosaurian dinosaur was discovered in a brick pit in Swindon, UK in 1874. Since then, numerous stegosaurian remains have been discovered from Europe, North America, Africa and Asia, and continue to be discovered regularly. Stegosaurs are known from the Middle Jurassic to the Early Cretaceous; no definitive evidence of the clade is known from younger deposits. New discoveries are improving our understanding of stegosaur biology and showing that stegosaurs were more morphologically diverse than was previously realized. A new phylogeny, which includes all valid stegosaurian taxa, largely agrees with previous studies and shows the European Dacentrurinae was sister taxon to Stegosaurus. Poor resolution at the base of Stegosauria is probably due to the fragmentary nature of many of the Chinese taxa.
38 citations
TL;DR: The present report presents substantial additional information about gastropods from the aftermath of the end-Permian mass extinction event, and reports the first certain Triassic report of the Permian subfamily Neilsoniinae and a holdover taxon.
Abstract: An Early Triassic (Griesbachian) gastropod fauna is reported from South China (Shanggan, Guangxi) and consists of four species: Bellerophon abrekensis, Wannerispira shangganensis Kaim & Nutzel sp. nov., Naticopsis sp., and Palaeonarica guangxinensis Kaim & Nutzel sp. nov. The taxon Wannerispira Kaim & Nutzel nom. nov. replaces Pagodina Wanner non Van Beneden. This is the first report of Bellerophon abrekensis from China. Previously, it was only known from its type locality in Far East Russia. Wannerispira shangganensis sp. is the first certain Triassic report of the Permian subfamily Neilsoniinae and represents a holdover taxon. The neritimorph Palaeonarica is reported for the first time from the Early Triassic and this is the oldest occurrence of this genus. Compared with other Griesbachian gastropods, the present material is relatively well preserved so that the taxonomy rests on rather firm ground. Very few nominal taxa have been reported from the Griesbachian and therefore the present report presents substantial additional information about gastropods from the aftermath of the end-Permian mass extinction event. The gastropod association from Shanggan shares one species with Primorye, Far East Russia (B. abrekensis). Two species, W. shangganensis and P. guangxinensis, closely resemble specimens reported from the Griesbachian of Oman. This could suggest that Griesbachian gastropod faunas of the Tethys were rather homogenous although the data are still scarce.
38 citations
TL;DR: A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a ~180 ka old sedimentary succession that provides new insights into the timing and nature of erosion-sedimentation processes in the Swiss lowlands.
Abstract: A 30 m-deep drill core from a glacially overdeepened trough in Northern Switzerland recovered a ~180 ka old sedimentary succession that provides new insights into the timing and nature of erosion–sedimentation processes in the Swiss lowlands. The luminescence-dated stratigraphic succession starts at the bottom of the core with laminated carbonate-rich lake sediments reflecting deposition in a proglacial lake between ~180 and 130 ka ago (Marine Isotope Stage MIS 6). Anomalies in geotechnical properties and the occurrence of deformation structures suggest temporary ice contact around 140 ka. Up-core, organic content increases in the lake deposits indicating a warming of climate. These sediments are overlain by a peat deposit characterised by pollen assemblages typical of the late Eemian (MIS 5e). An abrupt transition following this interglacial encompasses a likely hiatus and probably marks a sudden lowering of the water level. The peat unit is overlain by deposits of a cold unproductive lake dated to late MIS 5 and MIS 4, which do not show any direct influence from glaciers. An upper peat unit, the so-called «Mammoth peat», previously encountered in construction pits, interrupts this cold lacustrine phase and marks more temperate climatic conditions between 60 and 45 ka (MIS 3). In the upper part of the core, a succession of fluvial and alluvial deposits documents the Late Glacial and Holocene sedimentation in the basin. The sedimentary succession at Wehntal confirms that the glaciation during MIS 6 did not apparently cause the overdeepening of the valley, as the lacustrine basin fill covering most of MIS 6 is still preserved. Consequently, erosion of the basin is most likely linked to an older glaciation. This study shows that new dating techniques combined with palaeoenvironmental interpretations of sediments from such overdeepened troughs provide valuable insights into the past glacial history.
37 citations
TL;DR: In this article, the upper third of the Monte San Giorgio sequence has been excavated on a surface of around 40m2, and these new data complete those derived from new vertebrate finds (mainly fishes belonging to Saurichthys, Archaeosemionotus and Peltopleurus), allowing a better characterization of the basin.
Abstract: The Ladinian Cassina beds belong to the fossiliferous levels of the world-famous Middle Triassic Monte San Giorgio Lagerstatte (UNESCO World Heritage List, Canton Ticino, Southern Alps). Although they are a rich archive for the depositional environment of an important thanatocoenosis, previous excavations focused on vertebrates and particularly on marine reptiles. In 2006, the Museo Cantonale di Storia Naturale (Lugano) started a new research project focusing for the first time on microfacies, micropalaeontological, palaeoecological and taphonomic analyses. So far, the upper third of the sequence has been excavated on a surface of around 40 m2, and these new data complete those derived from new vertebrate finds (mainly fishes belonging to Saurichthys, Archaeosemionotus, Eosemionotus and Peltopleurus), allowing a better characterization of the basin. Background sedimentation on an anoxic to episodically suboxic seafloor resulted in a finely laminated succession of black shales and limestones, bearing a quasi-anaerobic biofacies, which is characterized by a monotypic benthic foraminiferal meiofauna and has been documented for the first time from the whole Monte San Giorgio sequence. Event deposition, testified by turbidites and volcaniclastic layers, is related to sediment input from basin margins and to distant volcanic eruptions, respectively. Fossil nekton points to an environment with only limited connection to the open sea. Terrestrial macroflora remains document the presence of emerged areas covered with vegetation and probably located relatively far away. Proliferation of benthic microbial mats is inferred on the basis of microfabrics, ecological considerations and taphonomic (both biostratinomic and diagenetic) features of the new vertebrate finds, whose excellent preservation is ascribed to sealing by biofilms. The occurrence of allochthonous elements allows an insight into the shallow-waters of the adjoining time-equivalent Salvatore platform. Finally, the available biostratigraphic data are critically reviewed.
35 citations
TL;DR: In this article, the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau were identified and discussed using more than 4,000 borehole data within a 430 km2-large area.
Abstract: The morphology of the Alpine and adjacent landscapes is directly related to glacial erosion and associated sediment transport. Here we report the effects of glacio-hydrologic erosion on bedrock topography in the Swiss Plateau. Specifically, we identify the presence of subsurface valleys beneath the city of Bern and discuss their genesis. Stratigraphic investigations of more than 4,000 borehole data within a 430 km2-large area reveal the presence of a network of >200 m-deep and 1,000 m-wide valleys. They are flat floored with steep sided walls and are filled by Quaternary glacial deposits. The central valley beneath Bern is straight and oriented towards the NNW, with valley flanks more than 20° steep. The valley bottom has an irregular undulating profile along the thalweg, with differences between sills and hollows higher than 50–100 m over a reach of 4 km length. Approximately 500 m high bedrock highlands flank the valley network. The highlands are dissected by up to 80 m-deep and 500 m-broad hanging valleys that currently drain away from the axis of the main valley. We interpret the valleys beneath the city of Bern to be a tunnel valley network which originated from subglacial erosion by melt water. The highland valleys served as proglacial meltwater paths and are hanging with respect to the trunk system, indicating that these incipient highland systems as well as the main gorge beneath Bern formed by glacial melt water under pressure.
33 citations
TL;DR: In this paper, the authors present results of a new bathymetric survey, based on single and multi-beam echosounder data, showing a well-structured lake bottom morphology, reflecting depositional and erosional processes that shape the lake floor.
Abstract: The current topographic maps of the Rhone Delta—and of Lake Geneva in general—are mainly based on hydrographic data that were acquired during the time of F.-A. Forel at the end of the nineteenth century. In this paper we present results of a new bathymetric survey, based on single- and multi-beam echosounder data. The new data, presented as a digital terrain model, show a well-structured lake bottom morphology, reflecting depositional and erosional processes that shape the lake floor. As a major geomorphologic element, the sub-aquatic Rhone Delta extends from the coastal platform to the depositional fans of the central plain of the lake at 310 m depth. 9 canyons cut the platform edge of the delta. These are sinuous (“meandering”) channels formed by erosional and depositional processes, as indicated by the steep erosional canyon walls and the depositional levees on the canyon shoulders. Ripples or dune-like morphologies wrinkle the canyon bottoms and some slope areas. Subaquatic mass movements are apparently missing on the delta and are of minor importance on the lateral lake slopes. Morphologies of the underlying bedrock and small local river deltas are located along the lateral slopes of Lake Geneva. Based on historical maps, the recent history of the Rhone River connection to the sub-aquatic delta and the canyons is reconstructed. The transition from three to two river branches dates to 1830–1840, when the river branch to the Le Bouveret lake bay was cut. The transition from two to one river branch corresponds to the achievement of the correction and dam construction work on the modern Rhone River channel between 1870 and 1880.
TL;DR: In this paper, long sediment cores were retrieved from the subsurface of Lake Lauerz that lies in the pathway of these landslides and that records strong runoff events with typical flood layers.
Abstract: The southern slopes of Rossberg mountain, Central Switzerland, on which one of the largest historic landslides of the Alpine region was released in 1806 ad (Goldauer Bergsturz), are prone to large-scale mass wasting processes. This has led to numerous sliding events, which are well-recognizable in the modern topography but lack accurate dating. In order to provide new insights into the timing and the processes associated with past landslides as well as into the frequency of exceptional flood events, long sediment cores were retrieved from the subsurface of Lake Lauerz that lies in the pathway of these landslides and that records strong runoff events with typical flood layers. Analyses of the recovered cores display a sedimentologic succession with variable fingerprints of past landslides and flood events, depending on the coring location within the lake. The landslide signature can be calibrated using the 1806 ad event: An organic-rich peaty unit, which is found in two cores located close to the rockmass impact, points towards a sudden, gravity spreading-induced lateral displacement of the swampy plain where parts of the rock mass were accumulating. This rapid lateral mobilization of soft sediments, and not the rock masses, acted as ultimate trigger for the reported ~15 m-high impulse waves on the lake. In the more distal areas, the 1806 ad event led to the deposition of a thick, organic-rich redeposited layer. The 10 m-long core from the distal basin covers a radiocarbon-dated ~2,000 years sedimentation history and contains a highly similar event layer that was deposited in 810 ± 60 ad. This layer is most likely the product of a major historic landslide, known as Rothener Bergsturz, which, based on scarce historical reports, was commonly dated to 1222 ad. In the 2,000 years record, we identify three periods with enhanced occurrence of flood turbidites dated to 580–850 ad, 990–1420 ad, and 1630–1940 ad. Among the 54 detected flood layers, 6 probably mark exceptionally heavy rainfall events that are dated to ~610, ~1160, ~1290, ~1660, ~1850, and ~1876 ad, the latter being associated to one of the most intense rainfall events ever recorded instrumentally in the region.
TL;DR: In this article, a study of the inneralpine basin of Hopfgarten focused on the analysis of basin fill in order to reveal its formation in relation to paleo-ice flow and tectonics is presented.
Abstract: We present a study of the inneralpine basin of Hopfgarten focused on the analysis of basin fill in order to reveal its formation in relation to paleo-ice flow and tectonics. The study is based on geological mapping as well as seismic (reflection and refraction) and geoelectrical surveys. The oldest sequence in the basin, identified by seismic stratigraphy at 400 m below surface, consists of coarse grained sediments of supposedly Oligocene to Miocene age, which subsided along faults linked to the Inn fault. Three superimposed sequences, each displaying baselaps in contact with a subglacially formed unconformity and sigmoid foresets, show pleniglacial conditions followed by a glaciolacustrine environment. The uppermost of these three sequences lies on top of last glacial maximum till (LGM; Wurmian Pleniglacial; MIS 2) and represents Termination I. The middle sequence is classified as Termination II following the Rissian Pleniglacial (MIS 6). The oldest glacial sequence cannot be constrained chronostratigraphically but might correlate with Termination V following the major glaciation of MIS 12. Limited glacial erosion during the LGM occurred only during the ice build-up phase. Further overdeepening was impeded due to topographic barrier and mutual blockades of glaciers within this highly dissected landscape. The occurrence and relative timing of the impediment was controlled by the onset of transfluences and thus by the altitude of coles. The higher amount of overdeepening during older glacial periods is explained by longer phases of free ice advance in the ice build up phase due to higher transfluences routes at that time. Thus, the preservation of older Pleistocene sequences within the basin may be the result of the lowering of watersheds from one glaciation to the next. Our model of an inverse relationship between glacial shaping of the surface and the subsurface may apply to similar Alpine landscapes as well.
TL;DR: Carpenter et al. as discussed by the authors described stegosaurian skin impressions from North America for the first time, as well as the first case of preservation of an impression of the integument that covered the dorsal plates of Stegosaurus in life.
Abstract: Dinosaur skin impressions are rare in the Upper Jurassic Morrison Formation, but different sites on the Howe Ranch in Wyoming (USA), comprising specimens from diplodocid, camarasaurid, allosaurid and stegosaurian dinosaurs, have proven to be a treasure-trove for these soft-tissue remains. Here we describe stegosaurian skin impressions from North America for the first time, as well as the first case of preservation of an impression of the integument that covered the dorsal plates of stegosaurian dinosaurs in life. Both have been found closely associated with bones of a specimen of the stegosaurian Hesperosaurus mjosi Carpenter, Miles and Cloward 2001. The scales of the skin impression of H. mjosi are very similar in shape and arrangement to those of Gigantspinosaurus sichuanensis Ouyang 1992, the only other stegosaurian dinosaur from which skin impressions have been described. Both taxa show a ground pattern of small polygonal scales, which in some places is interrupted by larger oval tubercles surrounded by the small scales, resulting in rosette-like structures. The respective phylogenetic positions of G. sichuanensis as a basal stegosaurian and H. mjosi as a derived form suggest that most stegosaurians had very similar skin structures, which also match the most common textures known in dinosaurs. The integumentary impression from the dorsal plate brings new data to the long-lasting debate concerning the function of dorsal plates in stegosaurian dinosaurs. Unlike usual dinosaur skin impressions, the integument covering the dorsal plates does not show any scale-like texture. It is smooth with long and parallel, shallow grooves, a structure that is interpreted as representing a keratinous covering of the plates. The presence of such a keratinous covering has affects on all the existing theories concerning the function of stegosaurian plates, including defense, thermoregulation, and display, but does not permit to rule out any of them.
TL;DR: In this article, a 7,150 square kilometre Raster Digital Elevation Model (DEM) of the bedrock surface of northern Switzerland was constructed based on surface and borehole information, together with pre-existing regional and local interpretations.
Abstract: Based on surface and borehole information, together with pre-existing regional and local interpretations, a 7,150 square kilometre Raster Digital Elevation Model (DEM) of the bedrock surface of northern Switzerland was constructed using a 25 m cell size. This model represents a further important step in the understanding of Quaternary sediment distribution and is open to a broad field of application and analysis, including hydrogeological, geotechnical and geophysical studies as well as research in the field of Pleistocene landscape evolution. An analysis of the overdeepened valleys in the whole model area and, more specifically in the Reuss area, shows that, in most cases, overdeepening is restricted to the areas covered by the Last Glaciation Maximum (LGM). However, at various locations relatively narrow overdeepened valleys outreach the tongue basins and the LGM ice shield limits. Therefore, an earlier and further-reaching glacial event has probably contributed significantly to the overdeepening of these valleys. No significant overdeepening has been identified downstream of Bottstein (Aare) and Kaiserstuhl (Rhine), although the ice extended considerably further downstream, at least during the most extensive glaciation. Except for the bedrock between Brugg and Bottstein, no overdeepened valleys are found significantly north of the outcrop of Mesozoic limestone of the Folded and Tabular Jura. A detailed analysis of the Reuss area shows that the Lake and Suhre valleys are separated from the Emmen—Gisikon Reuss valley basin by a significant bedrock barrier. The individual bedrock valleys are divided into several sub-basins, indicating a multiphase evolution of the valleys. Some of the swells or barriers separating the sub-basins coincide with known late LGM retreat stages. In the Suhre valley, an old fluvial valley floor with restricted overdeepened sections is documented.
TL;DR: In this article, a study of 633 tree-ring sequences sampled from 252 European larch (Larix decidua mill), Norway spruce (Picea abies (L.) Karst.), and Silver birch (Betula pendula Roth.) trees allowed reconstruction of 53 debris-flow events since AD 1736.
Abstract: Past debris-flow activity on the forested cone of the Geisstriftbach torrent (St. Niklaus, Valais, Swiss Alps) was assessed from growth disturbances in old conifer trees, providing a much improved record of past events. The study of 633 tree-ring sequences sampled from 252 European larch (Larix decidua Mill.), Norway spruce (Picea abies (L.) Karst.) and Silver birch (Betula pendula Roth.) trees allowed reconstruction of 53 debris-flow events since AD 1736. The spatial analysis of trees affected during particular events on the geomorphic map allowed for a spatial representation of individual events and a reconstruction of four flow patterns. Based on our results and Siegfried maps, we believe that before the formation of a dogleg near the cone apex in the late 1890s, debris flows preferentially used the channels located in the west-southwestern part of the Geisstriftbach cone. This study contributes to our understanding of debris-flow processes on cones and provides an example of how dendrogeomorphic techniques may help in the reconstruction and understanding of debris flows in Alpine areas.
TL;DR: The report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2009 as mentioned in this paper, and the three strongest events occurred about 15 km NW of Basel in southern Germany (ML 4.2), near Wildhaus in the Toggenburg (ML4.0) and near Bivio in Graubunden (ML 3.5).
Abstract: This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2009. During this period, 450 earthquakes and 68 quarry blasts were detected and located in the region under consideration. The three strongest events occurred about 15 km NW of Basel in southern Germany (ML 4.2), near Wildhaus in the Toggenburg (ML 4.0) and near Bivio in Graubunden (ML 3.5). Although felt by the population, they were not reported to have caused any damage. With a total of 24 events with ML ≥ 2.5, the seismic activity in the year 2009 was close to the average over the previous 34 years.
TL;DR: Size distribution of specimens of Prolobites from three studied localities show that, unlike in the co-occurring ammonoid species, most of the material belongs to adult individuals, and the potential fecundity and brooding behaviour of prolobites is hypothesized using the examples of post spawning egg care in Recent coleoids.
Abstract: Worldwide, the ammonoid genus Prolobites is only known from a few localities, and from these fossil beds almost all of the specimens are adults as shown by the presence of a terminal growth stage. This is in marked contrast to the co-occurring ammonoid genera such as Sporadoceras, Prionoceras, and Platyclymenia. Size distribution of specimens of Prolobites from three studied localities show that, unlike in the co-occurring ammonoid species, most of the material belongs to adult individuals. The morphometric analysis of Prolobites delphinus (Sandberger & Sandberger 1851) demonstrates the intraspecific variability including variants with elliptical coiling and that dimorphism is not detectable. The Prolobites material shows close resemblance to spawning populations of Recent coleoids such as the squid Todarodes filippovae Adam
1975. Possible mass spawning events are discussed in the context of the size distribution and limited geographic range of Prolobites. Finally, the potential fecundity and brooding behaviour of Prolobites is hypothesized using the examples of post spawning egg care in Recent coleoids.
TL;DR: Computer modelling and analyses provide additional information about feeding habits and plant preferences for Stegosaurus, and can be adapted for studying other comparable herbivorous taxa.
Abstract: Although the herbivorous dinosaur Stegosaurus (Ornithischia, Stegosauridae) is a well-described Late Jurassic taxon, little is known about the feeding habits and biomechanics of its homodont dentition. The presence of a rhamphotheca has been suggested, but it is still unknown how much such structure would have participated in the foraging behaviour of Stegosaurus. To better understand the feeding mechanism of this taxon, three-dimensional models of a Stegosaurus tooth were created, using the software ZBrush®. One model was simple and lacked serrations, whereas the other model included serrations. Those models were then transferred to the software Strand7®, where finite element analyses took place. The models were given material properties of enamel, based on studies done with crocodilian and mammalian teeth. In addition to that, bite forces were calculated for Stegosaurus, based on skull proportions. The results show little difference between the force distributions on the serrated and non-serrated models, indicating an efficient mechanism of stress dissipation that avoids high stresses being transferred to the jaw bones during biting. Digital plant models were also created to test the calculated bite forces in Stegosaurus, which suggests this animal was capable of biting through smaller branches. Computer modelling and analyses provide additional information about feeding habits and plant preferences for Stegosaurus, and can be adapted for studying other comparable herbivorous taxa.
TL;DR: The plated thyreophoran or stegosaurian dinosaur Stegosaurusarmatus was named in 1877 by Marsh for fragmentary remains from the Morrison Formation of Colorado, USA, but the validity of this genus has been questioned recently, raising the question: how much osteological difference among stEGosaur taxa is needed to separate genera from species?
Abstract: The plated thyreophoran or stegosaurian dinosaur Stegosaurusarmatus was named in 1877 by Marsh for fragmentary remains from the Morrison Formation (Upper Jurassic) of Colorado, USA. Subsequent discoveries from the same formation in Wyoming and Colorado (USA) have been assigned to separate stegosaurian genera and species, but most of these are no longer considered valid. More recently, a partial stegosaurian skeleton from Wyoming was named Hesperosaurusmjosi. However, the validity of this genus has been questioned recently, raising the question: how much osteological difference among stegosaur taxa is needed to separate genera from species? The question is examined vis-a-vis species and genus recognition in other dinosaurs, including iguanodonts, lambeosaurine iguanodontids, chasmosaurine ceratopsians, tyrannosaurid theropods, and diplodocid sauropods. The basis for taxonomic distinction is largely philosophical: if the species are morphologically distinct enough, they should be treated as separate genera. Based on these criteria, Hesperosaurus mjosi is a distinct taxon.
TL;DR: Stegosaurus armatus Marsh 1877, based on a partial tail and a very large dermal plate from the Morrison Formation (Late Jurassic) of Morrison, Wyoming, USA, is a nomen dubium as mentioned in this paper.
Abstract: Stegosaurus armatus Marsh 1877, based on a partial tail and a very large dermal plate from the Morrison Formation (Late Jurassic) of Morrison, Wyoming, USA, is a nomen dubium. Valid Morrison stegosaur species (with possible autapomorphies, dermal “armor” considered if present), with most holotypes consisting of a disarticulated partial postcranial skeleton at most, include: Hypsirhophus discurus Cope 1878 (characters of incomplete vertebrae, a dorsal and a caudal; Garden Park near Canon City, Colorado); Stegosaurus ungulatus Marsh 1879 (half skeleton with partial skull; three pairs of small flat dermal spines adjacent to terminal tail spikes; Quarry 12, Como Bluff near Como station, Wyoming; syntype is holotype of S. duplex Marsh 1887, half skeleton lacking armor; Quarry 11, Como Bluff); Diracodon laticeps Marsh 1881b (just partial dentaries with few teeth, diastema between predentary and tooth 1; Quarry 13, Como Bluff); Stegosaurus sulcatus Marsh 1887 (pair of ?tail spikes with greatly enlarged base; Quarry 13, Como Bluff); S. longispinus Gilmore 1914 (characters of distal caudal vertebrae, tail spikes: two pairs, sub-equal bases, transversely flattened, very elongate; Alcova, Wyoming); and Hesperosaurus mjosi Carpenter, Miles & Cloward, 2001 (?Stegosaurus mjosi; partial articulated skeleton with skull, no limbs, several plesiomorphic and autapomorphic characters, dorsal plates longer than tall; Wyoming). However, the well known valid nominal species, S. stenops Marsh 1887 (12 autapomorphies, three alternating flat plates adjacent to terminal tail spikes; Garden Park), is based on a virtually complete articulated skeleton lacking only the terminal caudal vertebrae and first pair of tail spikes. It includes 17 dermal plates, is still exposed as preserved on the block, and is the current basis for Stegosaurus. The International Commission on Zoological Nomenclature (ICZN) will be petitioned to designate S. stenops Marsh 1887 as the new type species of Stegosaurus Marsh 1877 in order to conserve Stegosauria Marsh 1877 and Stegosauridae Marsh 1880 (also Stegosauroidea, Stegosaurinae).
TL;DR: In this article, the age of the Moslavacka Gora Massif is estimated at ~90-100 ǫ using the method of electron microprobe based monazite dating.
Abstract: For a long time the Moslavacka Gora Massif in Croatia has been regarded as a major outcrop of Variscan crystalline basement of the South Tisia block. However, new geochronological data indicate that this massif consists of a Cretaceous S-type granite pluton intruding a Cretaceous low-pressure/high-temperature (LP/HT) metamorphic envelope. The age of the LP/HT metamorphism is estimated at ~90–100 Ma using the method of electron microprobe based monazite dating. The Central Granite was dated at 82 ± 1 Ma (LA-SF-ICP-MS zircon age). The metamorphic complex comprises mainly felsic anatexites and orthogneisses of granitic composition, some metapelites (paragneisses and mica schists) and amphibolites. Zircons from three different samples of metagranite were dated at 486 ± 6, 483 ± 6, and 491 ± 1 Ma, suggesting that most of the metamorphic complex represents an Early Ordovician granitic series. The Cretaceous regional metamorphism culminated in granulite facies conditions of ~750°C and 3–4 kbar. A retrograde metamorphic event at lower amphibolite facies conditions overprinted the metamorphic complex. This event is probably related to the intrusion of the Central Granite. The southeastern sector of the massif was additionally affected by post-granitic, predominantly NE oriented shearing at greenschist facies conditions. As yet there is no clear evidence for Variscan events in the Moslavacka Gora Massif. Mineral relics of a medium-pressure amphibolite facies metamorphism are preserved in amphibolites. They are older than the Cretaceous LP/HT regional metamorphism, but their age is presently unknown. Some indications for a Permian regional metamorphic event are provided by inherited zircons in the Central Granite that have been dated with a Permian age, and by Permian monazite relics in metapelites. The Cretaceous high heat flow regime recorded in the Moslavacka Gora Massif is unique in the subcrop of the Pannonian Basin and may be a local feature triggered by a mafic intrusion in the lower crust.
TL;DR: In this paper, geophysical explorations of three deep valleys, selected from different tectonic regimes in the Eastern Alps (Otz-, Oichten-, and Drau valleys), are presented and discussed.
Abstract: Results from geophysical explorations of three deep valleys, selected from different tectonic regimes in the Eastern Alps (Otz-, Oichten-, and Drau Valley), are presented and discussed. Ongoing tectonic deformation may use tectonic structures related to these valleys. However, seismic activity is low there. During the Wurm ice age, the thickness of the ice cover ranged between 300 and 1,500 m above present ground elevation. The geophysical investigations comprised reflection seismology, gravity- and resistivity surveys. The maximum depth down to the erosional base of the valleys varies from ~340 to 700 m. Distinct layer packages of the valley-infill at depths greater than 250 m were termed “old valley-fill”. Geophysical parameters and a comparison with the reflection seismic image of an intermediate layer at the recent Pasterze glacier suggest that the top of the “old valley-fill” represents the glacier bed during the decay of the Wurm glaciation. Deep erosion is not related to high basal shear stress. The confluence of tributary glaciers is apparently not a significant factor for deep erosion in our examples of deep alpine valleys. We conclude that deep erosion may be related to high water pressure at the glacier bed, supported by specific processes of tectonic weakening.
TL;DR: Les series phosphatees tunisiennes, dâge Paleocene-Eocene inferieur, sont constituees d’alternances de strates richement phosphatees (P2O5 ǫ 18%) and de strate intercalaires peu riches in P (P 2O5 nǫ 2%) as discussed by the authors.
Abstract: Les series phosphatees tunisiennes, d’âge Paleocene-Eocene inferieur, sont constituees d’alternances de strates richement phosphatees (P2O5 ≥ 18%) et de strates intercalaires peu riches en P (P2O5 ≤ 2%) Les strates phosphatees sont constituees d’un sediment argilo-carbonate servant de matrice (ou exogangue) a des grains phosphates, arrondis, de taille comprise majoritairement entre 100 et 500 μm, appeles pellets, et a des grains cylindriques d’origine fecale L’etude des pellets phosphates et de leur exogangue dans les strates riches et des sediments intercalaires peu riches en P dans le gisement de phosphates de Ras-Draâ (Bassin de Gafsa-Metlaoui, Tunisie) a reuni des observations microscopiques et diverses analyses chimiques des phases minerales presentes au sein des pellets et des sediments (matrices et sediments intercalaires) Le constituant apatitique majeur des grains est la carbonate-fluorapatite, ou francolite, dont une formule structurale, determinee sur un echantillon representatif, est la suivante: (Ca463Mg013Na022)(PO4)251(CO3)048)(OH077F023) Les constituants des sediments encaissant ces grains (matrice) et des strates intercalaires sont de nature mineralogique essentiellement argileuse, carbonatee ou siliceuse (opale ou quartz) Les observations microscopiques et geochimiques de ces differentes phases conduisent a reconnaitre que les pellets sont des corps etrangers au sein de leur matrice et de composition tout a fait independante de celle de leur exogangue Les elements fecaux cylindriques et les pellets arrondis qui en seraient derives par fragmentation et erosion, auraient ete produits par des poissons, sous forme de feces riches en P et en matiere organique et resistants vis a vis de la dispersion mecanique Cette derniere propriete a valu a leur contenu de n’etre pas disperse au cours de la sedimentation et des remaniements sedimentaires Leur contenu a connu, tout au long de leur evolution diagenetique, des conditions reductrices strictes
TL;DR: The Prehodavci Formation is up to 15 m thick, consists of Rosso Ammonitico type limestone and is subdivided into three members: the lower, well-bedded bioclastic limestone with Fe-Mn nodules, passing into light-grey, faintly nodular limestone.
Abstract: The Julian Alps are located in NW Slovenia and structurally belong to the Julian Nappe where the Southern Alps intersect with the Dinarides. In the Jurassic, the area was a part of the southern Tethyan continental margin and experienced extensional faulting and differential subsidence during rifting of the future margin. The Mesozoic succession in the Julian Alps is characterized by a thick pile of Upper Triassic to Lower Jurassic platform limestones of the Julian Carbonate Platform, unconformably overlain by Bajocian to Tithonian strongly condensed limestones of the Prehodavci Formation of the Julian High. The Prehodavci Formation is up to 15 m thick, consists of Rosso Ammonitico type limestone and is subdivided into three members. The Lower Member consists of a condensed red, well-bedded bioclastic limestone with Fe–Mn nodules, passing into light-grey, faintly nodular limestone. The Middle Member occurs discontinuously and consists of thin-bedded micritic limestone. The Upper Member unconformably overlies the Lower or Middle Members. It is represented by red nodular limestone, and by red-marly limestone with abundant Saccocoma sp. The Prehodavci Formation unconformably overlies the Upper Triassic to Lower Jurassic platform limestone of the Julian Carbonate Platform; the contact is marked by a very irregular unconformity. It is overlain by the upper Tithonian pelagic Biancone (Maiolica) limestone. The sedimentary evolution of the Julian High is similar to that of Trento Plateau in the west and records: (1) emergence and karstification of part of the Julian Carbonate Platform in the Pliensbachian, or alternatively drowning of the platform and development of the surface by sea-floor dissolution; (2) accelerated subsidence and drowning in the Bajocian, and onset of the condensed pelagic sedimentation (Prehodavci Formation) on the Julian High; (3) beginning of sedimentation of the Biancone limestone in the late Tithonian.
TL;DR: In this paper, the authors studied two well-exposed parallel fault zones from set 4, the Rezli fault zones (RFZ) in the Wildhorn Nappe, which are SW-dipping oblique-slip faults with a total displacement across the two fault zones of ~200m vertically and ~680m horizontally.
Abstract: The Helvetic nappes in the Swiss Alps form a classic fold-and-thrust belt related to overall NNW-directed transport. In western Switzerland, the plunge of nappe fold axes and the regional distribution of units define a broad depression, the Rawil depression, between the culminations of Aiguilles Rouge massif to the SW and Aar massif to the NE. A compilation of data from the literature shows that, in addition to thrusts related to nappe stacking, the Rawil depression is cross-cut by four sets of brittle faults: (1) NE-SW striking normal faults, (2) NW-SE striking normal faults and joints, (3) ENE-WSW striking and (4) WNW-ESE striking normal plus dextral oblique-slip faults. Fault set 1 was probably initiated during sedimentation and reactivated during nappe stacking, whereas the other fault sets formed after emplacement of the Helvetic nappes. We studied in detail two well-exposed parallel fault zones from set 4, the Rezli fault zones (RFZ) in the Wildhorn Nappe. They are SW-dipping oblique-slip faults with a total displacement across the two fault zones of ~200 m vertically and ~680 m horizontally. The fault zones crosscut four different lithologies: limestone, intercalated marl and limestone, marl and sandstone. The internal architecture of the RFZ strongly depends on the lithology in which they developed. In the limestones, they consist of extension veins, stylolites, cataclasites and cemented gouge, in the intercalated marls and limestones of shear zones, brittle fractures and chaotic folds, in the marls of anastomosing shear zones, pressure solution seams and veins and in the sandstones of coarse breccia, brittle faults and extension veins. Sharp, discrete fault planes within the broader fault zones cross-cut all lithologies. Fossil fault zones in the Rezli area can act as a model for studying processes still occurring at deeper levels in this seismically active region.
TL;DR: Wegener et al. as mentioned in this paper argued that the Alps are the result of collisions between light continents drifting and floating on denser formations of the Earth's interior, also present at the bottom of the oceans.
Abstract: At the advent of the twentieth century, geologists believed that folded continental mountain chains like the Alps were due to horizontal compression, resulting from contractions of the Earth’s crust as it cooled. In 1918, Albert Heim defended this point of view and illustrated it with a geological section across Switzerland. In 1915, however, and in short notes as early as 1912, Alfred Wegener in Die Entstehung der Kontinente und Ozeane (The Origin of Continents and Oceans) proposed that mountains were the result of collisions between light continents drifting and floating on denser formations of the Earth’s interior, also present at the bottom of the oceans. Before this (1906), Otto Ampferer had already proposed the association of folds with active movements of material inside the Earth. Wegener used numerous morphological, geological, and gravimetric data to justify his theory. He was innovative in his successful use of paleogeographic and paleoclimatologic reconstitutions. Although very popular, his theory only received reserved approval from the active scientific community. Alpine geologists found it too audacious and too far removed from the field data. In the first critical analysis written in French (1922), Elie Gagnebin welcomed it as a working hypothesis, but was very reserved regarding the arguments of a geophysicist who, in his opinion, was not sufficiently versed in structural geology. In contrast, Emile Argand integrated Wegener’s theory into his conception of the evolution of the Alps already in 1916. At that time, he judged the Alpine orogeny to have been the result of permanent compression and proposed that its whole history had been dominated by what he called embryonic tectonics, a compressional concept which he illustrated so admirably that it had an incomparable and lasting success. However, he himself abandoned it in his major work, La Tectonique de l’Asie (The Tectonics of Asia), in favour of an evolution that first originated in an extension regime, finally leading to the splitting of the continental crust, with local emergence of basic rocks, constituting the bottom of new oceanic floors. It is at the slope of these continental margins, and at their foot, that geosynclines are formed by the large accumulation of sediments transported by submarine slumping. During the following compressive stage, slices of basic ocean floor are transported upwards between overlapping continental masses, forming extensive ophiolitic zones. Although admired for his enormous accomplishment, La Tectonique de l’Asie remained ignored for its most innovative propositions, which clearly foreshadow plate tectonics. After this work, Argand practically abandoned geology. His last publication (1934), Guide geologique de la Suisse: la zone pennique (Geological Guide to Switzerland: the Pennine Zone), revived his argument of the early evolution of the geosyncline in a context of extension, followed by thrusts involving the ocean floor. Unfortunately, the concept had no greater success than at its first appearance.
TL;DR: A stegosaur tooth from the Early Cretaceous (Berriasian) Purbeckian deposits of Cherves-de-Cognac (Charente), southwestern France was examined in detail using microtomography as discussed by the authors.
Abstract: The spotty nature of the terrestrial fossil record for the Mesozoic hinders a more complete understanding of dinosaur diversity. For stegosaurs (Ornithischia), the plated dinosaurs, only a few and fragmentary remains are reported from the Early Cretaceous of Europe. A recent revision concluded that only a partial vertebra of the nomen dubiumCraterosaurus (?Aptian, England) could be considered as stegosaurian. Here we report on a stegosaur tooth from the Early Cretaceous (Berriasian) Purbeckian deposits of Cherves-de-Cognac (Charente), southwestern France. This tiny tooth was examined in detail using microtomography. Comparisons being limited by the rarity of stegosaur tooth rows material (e.g., from the skull of the holotype of Stegosaurus stenops) and dental material, notably from Europe, we observed new material of cf. Stegosaurus armatus and Hesperosaurus mjosi from the Upper Jurassic Morrison Formation of Wyoming (USA). The tooth shows the most similarities to the Late Jurassic genera Stegosaurus and Hesperosaurus, but differs in having a distinctive downwardly arched (V-shaped) cingulum on the ?lingual face (maxillary tooth hypothesis). It is referred to as Stegosauria indeterminate, a medium-sized quadrupedal herbivore that inhabited an emerged land between the Armorican Massif and the Massif Central. This finding is the first evidence of a stegosaur from the Early Cretaceous of France and a welcome addition to the meagre European record of that time. In addition, it is the second stegosaurian tooth crown reported from Europe. The assemblage of ornithischians of Cherves-de-Cognac shares some similarities with that of the Early Cretaceous (Berriasian) of the Purbeck Limestone Group, southern England. The relative rarity of ornithischian osteological remains in both Purbeckian environments suggests that most of these dinosaurs were mainly inhabitants of inland terrestrial palaeoenvironments.
TL;DR: In this article, detrital zircons from a contact metamorphic sample of the Brixen Quartzphyllite from the innermost part of the contact aureole adjacent to the brixen granodiorite yielded three different Precambrian concordia ages.
Abstract: Laser ablation ICP-MS U–Pb zircon geochronology of detrital zircons from a contact metamorphic sample of the Brixen Quartzphyllite from the innermost part of the contact aureole adjacent to the Brixen granodiorite yielded three different Precambrian concordia ages: zircon cores and an older generation of zircons give a maximum age of 2,023 ± 31 Ma, zircon rims and a younger generation of single grains yield a concordia age of 882 ± 19 Ma. A third generation of single zircon grains yields an age of 638 ± 20 Ma. In contrast to Austroalpine quartzphyllite complexes from the Eastern Alps neither Cambrian/Ordovician (570–450 Ma) nor Carboniferous (360–340 Ma) ages on single zircons have been observed so far in these samples. These ages provide evidence of a complex pre-Variscan evolution of the Southalpine basement since these data suggest a possible affinity of the Southalpine basement to Gondwana-related tectonic elements as well as to a possible Cadomian hinterland. This study shows that dating detrital zircons of the Brixen Quartzphyllites has great potential for providing age constraints on the complex geological evolution of the Southalpine basement.
TL;DR: In this article, a detailed investigation of the protoglobigerinids from the Kimmeridgian section of the Montagne de Crussol, SE France is presented.
Abstract: A detailed investigation of the protoglobigerinids from the Kimmeridgian section of the Montagne de Crussol, SE France is presented. This monotonous succession of predominantly carbonate beds represents peri-platform hemipelagic deposits, well dated by ammonites. Three species were determined in thin sections and in isolated forms after extraction by acetolysis. Favusella? parva (Kuznetsova) is the most common species occurring in almost the entire succession from the Orthosphinctes to the Beckeri zones. Favusella hoterivica (Subbotina) has been retrieved less frequently from the Platynota to the Beckeri zones, and it is its oldest occurrence. The rare Globuligerina bathoniana (Pazdrowa) occurs only in the Late Kimmeridgian. Based on our study and the review of the literature a palaeogeographical map was plotted, showing that most of the protoglobigerinid occurrences are in deep water facies of the northern margin and central part of the Tethys. These records demonstrate the presence of Globuligerina bathoniana, G. oxfordiana (Grigelis), Favusella hoterivica, F.? parva and Compactogerina stellapolaris (Grigelis) in the Kimmeridgian.