Episodic and long-lasting Paleozoic felsic magmatism in the pre-Alpine basement of the Suretta nappe (eastern Swiss Alps)

The Suretta nappe of eastern Switzerland contains a series of meta-igneous rocks, with the Rofna Porphyry Complex (RPC) being the most prominent member. We present LA-ICP-MS U–Pb zircon data from 12 samples representing a broad spectrum of meta-igneous rocks within the Suretta nappe, in order to unravel the pre-Alpine magmatic history of this basement unit. Fine-grained porphyries and coarse-grained augengneisses from the RPC give crystallization ages between 284 and 271 Ma, which either represent distinct magma pulses or long-lasting magmatic activity in a complex magma chamber. There is also evidence for an earlier Variscan magmatic event at ~320–310 Ma. Mylonites at the base of the Suretta nappe are probably derived from either the RPC augengneisses or another unknown Carboniferous–Permian magmatic protolith with a crystallization age between 320 and 290 Ma. Two polymetamorphic orthogneisses from the southern Suretta nappe yield crystallization ages of ~490 Ma. Inherited zircon cores are mainly of late Neoproterozoic age, with minor Neo- to Paleoproterozoic sources. We interpret the Suretta nappe as mainly representing a Gondwana-derived crustal unit, which was subsequently intruded by minor Cambrian–Ordovician and major Carboniferous–Permian magmatic rocks. Finally, the Suretta nappe was thrust into its present position during the Alpine orogeny, which hardly affected the U–Pb system in zircon.

Fully Automatic CT Segmentation for Computer-Assisted Pre-operative Planning of Hip Arthroscopy

Extraction of both pelvic and femoral surface models of a hip joint from CT data for computer-assisted pre-operative planning of hip arthroscopy is addressed. We present a method for a fully automatic image segmentation of a hip joint. Our method works by combining fast random forest (RF) regression based landmark detection, atlas-based segmentation, with articulated statistical shape model (aSSM) based hip joint reconstruction. The two fundamental contributions of our method are: (1) An improved fast Gaussian transform (IFGT) is used within the RF regression framework for a fast and accurate landmark detection, which then allows for a fully automatic initialization of the atlas-based segmentation; and (2) aSSM based fitting is used to preserve hip joint structure and to avoid penetration between the pelvic and femoral models. Validation on 30 hip CT images show that our method achieves high performance in segmenting pelvis, left proximal femur, and right proximal femur surfaces with an average accuracy of 0.59 mm, 0.62 mm, and 0.58 mm, respectively.

Manganiferous minerals of the epidote group from the Archaean basement of West Greenland

The chemical compositions and crystal structures of Mn3+-containing minerals from the epidote group in Greenland rocks are investigated and described in detail. They occur in hydrothermally altered Archaean mafic sequences within the gneissic complex of the North Atlantic craton of West Greenland. The Mn-containing minerals have a characteristic red to pink colour. A detailed microchemical study shows a significant inter- and intra-sample variation in Mn content. The samples from different parageneses can be classified as Mn-bearing epidote and Mn-bearing clinozoisite. The intra-sample variation in the content of Al, Fe and Mn is on a very fine scale, but still allows for identification of a negative correlation between Mn and Fe. Textures indicate different stages of growth. Crystal chemical data are compared with literature data and illustrate the basic systematic differences between the influence of Fe and Mn on the crystal structure of the epidote group minerals.

The Basement of the Deccan Traps and Its Madagascar Connection: Constraints from Xenoliths

Paleogeographic reconstructions of India and Madagascar before their late Cretaceous rifting juxtapose the Antongil Block of Madagascar against the Deccan Traps of India, indicating that the Western Dharwar Craton extends below the Deccan lavas. Some recent studies have suggested that the South Maharashtra Shear Zone along the northern Konkan coast of India limits the northern extent of the Western Dharwar Craton, implying that the craton does not extend below the Deccan Traps, raising a question mark on paleogeographic reconstructions of India and Madagascar. The continuity of the Western Dharwar Craton north of the South Maharashtra Shear Zone below the Deccan Traps—or its lack thereof—is critical for validating tectonic models correlating Madagascar with India. In this study, zircons in tonalitic basement xenoliths hosted in Deccan Trap dykes were dated in situ, using the U-Pb isotope system. The data furnish U-Pb ages that define three populations at 2527 ± 6, 2456 ± 6, and 2379 ± 9 Ma. The 2527 ± 6 Ma ages correspond to the igneous crystallization of the tonalites, whereas the 2456 ± 6 and 2379 ± 9 Ma ages date metamorphic overprints. The results help to establish for the first time that the basement is a part of the Neoarchean granitoid suite of the Western Dharwar Craton, which extends northward up to at least Talvade in central and Kihim beach in the western Deccan. By implication, the South Maharashtra Shear Zone cannot be the northern limit of the Western Dharwar Craton. The granitoids are correlated with the Neoarchean felsic intrusions (2.57–2.49) of the Masaola suite in the Antongil Block of Madagascar, supporting the existence of a Neoarchean Greater Dharwar Craton comprising the Western Dharwar Craton and the Antongil-Masora Block.

Effects of variation in nest curtain design on pre-laying behaviour of domestic hens

Laying hens in loose-housing systems select a nest daily in which to lay their eggs among many identical looking nests, they often prefer corner nests. We investigated whether heterogeneity in nest curtain appearance – via colours and symbols – would influence nest selection and result in an even distribution of eggs among nests. We studied pre-laying behaviour in groups of 30 LSL hens across two consecutive trials with eight groups per trial. Half of the groups had access to six identical rollaway group-nests, while the others had access to six nests of the same type differing in outer appearance. Three colours (red, green, yellow) and three black symbols (cross, circle, rectangle) were used to create three different nest curtain designs per pen. Nest position and the side of entrance to the pens were changed at 28 and 30 weeks of age, respectively, whereby the order of changes was counterbalanced across trials. Nest positions were numbered 1–6, with nest position 1 representing the nest closest to the pen entrance. Eggs were counted per nest daily from week of age 18 to 33. Nest visits were recorded individually with an RFID system for the first 5 h of light throughout weeks 24–33. Hens with access to nests differing in curtain appearance entered fewer nests daily than hens with identical nests throughout the study but both groups entered more nests with increasing age. We found no other evidence that curtain appearance affected nest choice and hens were inconsistent in their daily nest selection. A high proportion of eggs were laid in corner nests especially during the first three weeks of lay. The number of visits per egg depended upon nest position and age: it increased with age and was higher after the nest position change than before in nest position 1, whereas it stayed stable over time in nest position 6. At 24 weeks of age, gregarious nest visits (hens visiting an occupied nest when there was at least one unoccupied nest) and solitary nest visits (hens visiting an unoccupied nest when there was at least one occupied nest) accounted for a similar amount of nest visits, however, after the door switch, gregarious nest visits made up more than half of all nest visits, while the number of solitary nest visits had decreased. The visual cues were too subtle or inadequate for hens to develop individual preferences while nest position, entrance side, age and nest occupancy affected the quantity and type of nest visits.

The tectonometamorphic evolution of the Sesia–Dent Blanche nappes (internal Western Alps): review and synthesis

This study reviews and synthesizes the present knowledge on the Sesia–Dent Blanche nappes, the highest tectonic elements in the Western Alps (Switzerland and Italy), which comprise pieces of pre-Alpine basement and Mesozoic cover. All of the available data are integrated in a crustal-scale kinematic model with the aim to reconstruct the Alpine tectono-metamorphic evolution of the Sesia–Dent Blanche nappes. Although major uncertainties remain in the pre-Alpine geometry, the basement and cover sequences of the Sesia–Dent Blanche nappes are seen as part of a thinned continental crust derived from the Adriatic margin. The earliest stages of the Alpine evolution are interpreted as recording late Cretaceous subduction of the Adria-derived Sesia–Dent Blanche nappes below the South-Alpine domain. During this subduction, several sheets of crustal material were stacked and separated by shear zones that rework remnants of their Mesozoic cover. The recently described Roisan-Cignana Shear Zone of the Dent Blanche Tectonic System represents such a shear zone, indicating that the Sesia–Dent Blanche nappes represent a stack of several individual nappes. During the subsequent subduction of the Piemonte–Liguria Ocean large-scale folding of the nappe stack (including the Roisan-Cignana Shear Zone) took place under greenschist facies conditions, which indicates partial exhumation of the Dent Blanche Tectonic System. The entrance of the Briançonnais micro-continent within the subduction zone led to a drastic change in the deformation pattern of the Alpine belt, with rapid exhumation of the eclogite-facies ophiolite bearing units and thrust propagation towards the foreland. Slab breakoff probably was responsible for allowing partial melting in the mantle and Oligocene intrusions into the most internal parts of the Sesia–Dent Blanche nappes. Finally, indentation of the Adriatic plate into the orogenic wedge resulted in the formation of the Vanzone back-fold, which marks the end of the pervasive ductile deformation within the Sesia–Dent Blanche nappes during the earliest Miocene.

Pre-Columbian human occupation patterns in the eastern plains of the Llanos de Moxos, Bolivian Amazonia

Despite an increasing number of publications regarding the Pre-Columbian earthworks of the Llanos de Moxos, there have been no serious attempts to undertake a systematic survey of the archaeological remains of this lowland region in the Bolivian Amazon. Based on the GIS analysis of data gathered in the field and retrieved from satellite images, we discuss the spatial distribution of the Pre-Columbian settlements in a 4500 Km2 area of the Llanos de Moxos to the east of Trinidad, capital of the Beni Department, and their relationship with the geographical settings. Our findings shed new light on the prehistory of the region and bear important implications for our understanding of the impact of Pre-Columbian human occupation.

[Prevalence of heart murmurs, aortic and pulmonic stenosis in boxers presented for pre-breeding exams in Switzerland]

Boxer are predisposed to subaortic (SAS) and pulmonic stenosis (PS). To decrease the prevalence, pre-breeding cardiologic exams were performed in the last years. In our study the results of 309 pre-breeding exams of boxers presented between 1999 and 2008 were evaluated retrospectively. The overall prevalence of heart murmurs was 26.5 %. A SAS was diagnosed in 25 (8.1 %) and a PS in 10 (3.3 %) dogs. A combination of both defects was found in 7 (2.3 %) Boxers. Animals with a heart murmur of at least grade 3/6 had a significantly higher peak aortic flow velocity (VmaxAo) than animals without or only soft heart murmurs. Over the study period both the frequency of heart murmurs and diagnosis of SAS and PS decreased.

Upper crustal deformation in continent-continent collision: A case study from the Bernard nappe complex (Valais, Switzerland)

The Penninic nappes in the Swiss Alps formed during continental collision between the Adriatic and European plates in Cenozoic times. Although intensely studied, the finite geometry of the basement-bearing Penninic nappes in western Switzerland has remained a matter of debate for decades (e.g., “Siviez-Mischabel dilemma”) and the paleogeographic origin of various nappes has been disputed. Here, we present new structural data for the central part of the Penninic Bernard nappe complex, which contains pre-Permian basement and Permo-Mesozoic metasedimentary units. Our lithological and structural observations indicate that the discrepancy between the different structural models proposed for the Bernard nappe complex can be explained by a lateral discontinuity. In the west, the presence of a Permian graben caused complex isoclinal folding, whereas in the east, the absence of such a graben resulted mainly in imbricate thrusting. The overall geometry of the Bernard nappe complex is the result of three main deformation phases: (1) detachment of Mesozoic cover sediments along Triassic evaporites (Evolène phase) during the early stages of collision, (2) Eocene top-to-the-N(NW) nappe stacking (Anniviers phase), and (3) subsequent backfolding and backshearing (Mischabel phase). The southward localized backshearing is key to understand the structural position and paleogeographic origin of units, such as the Frilihorn and Cimes Blanches “nappes” and the Antrona ophiolites. Based on these observations, we present a new tectonic model for the entire Penninic region of western Switzerland and discuss this model in terms of continental collision zone processes.