The St. Marcel Valley, Western Alps: metaophiolites, metasedimentary sequence and tectonic setting

In the Southern Aosta Valley, the St. Marcel Valley metaophiolites consist of mainly metavolcanics and their sedimentary cover metamorphosed under HP subduction-related metamorphism. A detailed geological map carried out in the St. Marcel Valley reveals that the metasedimentary cover, although transposed by the Alpine tectonics, is essentially made of three main terms, that are Mn-rich metaquartzites, marble, and calcschists. The metasedimentary sequence is quite comparable with the unmetamorphosed sequence made of radiolarian cherts, Calpionella limestones and Palombini shales covering the Ligurian ophiolites. The St. Marcel Valley metaophiolites represent the upper crustal section of the Mesozoic Tethyan ocean and its pelagic sedimentary cover, overthrusting the serpentinite unit of the Mount Avic, to the East. Within the Piemonte nappe stack, the St.Marcel metaophiolites are located at the higher structural level

Geology of the Saint-Marcel valley metaophiolites (Northwestern Alps, Italy)

The geological map of the Saint-Marcel valley at the scale of 1:20,000 illustrates the tectonic setting of metaophiolites from the southern Aosta Valley, in the Italian side of the Western Alpine belt. The map highlights the sharp contact between the metaophiolitic basement and its metasedimentary cover, which mainly consists of quartzites, marbles, and calcschists. In spite of the Alpine tectonics, this contact is regarded as deriving from the original oceanic crust/sediments interface. Metaophiolites mostly consist of metabasalts hosting Fe\u2013Cu sulphide mineralisations, characterised by high-pressure metamorphic imprint. These rocks likely represent the shallowest portion of the Tethyan oceanic lithosphere created near the axis of the slow-spreading ridge where hydrothermal fluid circulation was active. Selected key-sections through metasediments reveal a consistent internal lithostratigraphy, in spite of the pervasive metamorphic and tectonic reworking acting during the Alpine evolution. Metasediments reflect various sedimentation episodes starting from pelagic and proximal settings to the onset of the orogenic stage. The Saint-Marcel valley metasediments thus reflect a changing in the sedimentation environments through time and space during the overall geologic evolutio

Spinel-peridotites of the Frido Unit ophiolites (Southern Apennine-Italy): evidence for oceanic evolution

The ophiolitic rocks of the Frido Unit include serpentinites derived from a lherzolitic and subordinately harzburgitic mantle, as suggested by microstructural and petrographical features. The serpentinites are englobed in tectonic slices where they are associated with metadolerite dykes and medium to high-grade metamorphic rocks such as amphibolite, gneiss, granofels as well as gabbro and basalt with pillow structures. The matrix of tectonic slices is mainly composed of calcschists and phyllites. The serpentinites of the Frido Unit show pseudomorphic and vein textures. Primary mantle minerals are represented by olivine, clinopyroxene, orthopyroxene and orthopyroxene exolutions, and spinel and are identifiable by of the occurrence of either fresh minerals or pseudomorphs maintaining the mineral shape. Pseudomorphic minerals are serpentine, magnetite, chlorite, and amphibole. Olivine is replaced by serpentine forming a mesh texture; orthopyroxene is mostly altered to bastite; in some cases it shows exsolution lamellae of clinopyroxene and kink bands; fresh orthopyroxene is preserved as exsolution inside clinopyroxene porphyroclasts. Clinopyroxene is armoured by amphibole rim. Spinel shows a holly-leaf habit and is often armoured by a corona of Crchlorite. The core of the analyzed spinel has a Cr-Al spinel composition corresponding to chromite (Al 2O 3=29-31 wt%; Cr 2O 3=28-37 wt%), whereas the rim has a Fe-Cr spinel composition corresponding to ferritchromite (Al 2O 3=1-2% wt; Cr 2O 3=28-30 wt%). The Cr-Al spinel/ferritchromite ratio may be various in different spinel porphyroclasts. Magnetite replaces spinel or occurs within the mesh textured serpentine. The metamorphic assemblages in the Frido Unit serpentinites allow to infer qualitatively the physical conditions operating during serpentinization. The metamorphic mineral assemblages are typical of the greenschistamphibolite transition and greenschist facies conditions, as suggested by the occurrence of tremolite/actinolite replacing clinopyroxene and of Cr-chlorite and ferritchromite after Alrich chromite. These minerals were produced by interactions between hydrothermal fluids and mantle peridotites. Serpentinites are cut by veins filled with mineralogical assemblages typical of the prehnite-pumpellyite facies, likely related to later orogenic Apennine evolution, as observed in the surrounding rocks of the same tectonic unit. Instead, early orogenic LT blueschist facies minerals recorded in the nearby metadolerite dykes were not observed in the serpentinites

A Jurassic oceanic core complex in the high-pressure Monviso ophiolite (western Alps, NW Italy)

The eclogite-facies Monviso ophiolite in the western Alps displays a complex record of Jurassic rift-drift, subduction zone, and Cenozoic collision tectonics in its evolutionary history. Serpentinized lherzolites intruded by 163 \ub1 2 Ma gabbros are exposed in the footwall of a thick shear zone (Baracun shear zone) and are overlain by basaltic lava flows and synextensional sedimentary rocks in the hanging wall. Mylonitic serpentinites with sheared ophicarbonate veins and talc-and-chlorite schist rocks within the Baracun shear zone represent a rock assemblage that formed from seawater-derived hydrothermal fluids percolating through it during intra-oceanic extensional exhumation. A Lower Cretaceous calc-schist, marble, and quartz-schist metasedimentary assemblage unconformably overlies the footwall and hanging-wall units, representing a postextensional sequence. The Monviso ophiolite, Baracun shear zone, and the associated structures and mineral phases represent core complex formation in an embryonic ocean (i.e., the Ligurian-Piedmont Ocean). The heterogeneous lithostratigraphy and the structural architecture of the Monviso ophiolite documented here are the products of rift-drift processes that were subsequently overprinted by subduction zone tectonics, and they may also be recognized in other (ultra)high-pressure belts worldwid

Superposed sedimentary and tectonic block-in-matrix fabrics in a subducted serpentinite m\ue9lange (High-pressure zermatt saas ophiolite, western alps)

The primary stratigraphic fabric of a chaotic rock unit in the Zermatt Saas ophiolite of the Western Alps was reworked by a polyphase Alpine tectonic deformation. Multiscalar structural criteria demonstrate that this unit was deformed by two ductile subduction-related phases followed by brittle-ductile then brittle deformation. Deformation partitioning operated at various scales, leaving relatively unstrained rock domains preserving internal texture, organization, and composition. During subduction, ductile deformation involved stretching, boudinage, and simultaneous folding of the primary stratigraphic succession. This deformation is particularly well-documented in alternating layers showing contrasting deformation style, such as carbonate-rich rocks and turbiditic serpentinite metasandstones. During collision and exhumation, deformation enhanced the boudinaged horizons and blocks, giving rise to spherical to lozenge-shaped blocks embedded in a carbonate-rich matrix. Structural criteria allow the recognition of two main domains within the chaotic rock unit, one attributable to original broken formations reflecting turbiditic sedimentation, the other ascribable to an original sedimentary m\ue9lange. The envisaged geodynamic setting for the formation of the protoliths is the Jurassic Ligurian-Piedmont ocean basin floored by mostly serpentinized peridotites, intensely tectonized by extensional faults that triggered mass transport processes and turbiditic sedimentation

Sodium oxybate in narcolepsy with cataplexy: Zurich sleep center experience

Sodium oxybate (SO; Xyrem®) has been approved in most countries for treatment of narcolepsy and cataplexy. In this study, we present a single-center experience of a series of 18 patients with narcolepsy with cataplexy (18/18 DQB1*0602 positive, 17/17 with low/absent cerebrospinal fluid hypocretin) in whom SO was prescribed. After 26 ± 13 months, 13/18 patients were still on SO at a mean dosage of 6.1 ± 1.2 g (in 8 of them in combination with stimulants). The following significant effects were observed: improved subjective sleepiness (12/13), cataplexy (13/13; median number of attacks from 20 to 1/month), hallucinations (8/10) and sleep paralysis (8/8); increase in mean sleep latency on the Maintenance of Wakefulness Test (from 5.5 to 17.4 min) and sleep/rest efficiency on actigraphy (from 61 to 76%); decrease in Epworth Sleepiness Scale score (from 18 to 14), sleep onset REM periods on the Multiple Sleep Latency Test (from 3.6 to 2.4) and errors in the Steer-Clear Test (from 11 to 2%). Five patients discontinued SO because of insufficient compliance (n = 2), lack of efficiency (n = 1) and side effects (n = 1). These data confirm and expand previous reports on the good effects and tolerability of SO as a treatment for narcolepsy with cataplexy

Rapid Enzymatic Response to Compensate UV Radiation in Copepods

Ultraviolet radiation (UVR) causes physical damage to DNA, carboxylation of proteins and peroxidation of lipids in copepod crustaceans, ubiquitous and abundant secondary producers in most aquatic ecosystems. Copepod adaptations for long duration exposures include changes in behaviour, changes in pigmentation and ultimately changes in morphology. Adaptations to short-term exposures are little studied. Here we show that short-duration exposure to UVR causes the freshwater calanoid copepod, Eudiaptomus gracilis, to rapidly activate production of enzymes that prevent widespread collateral peroxidation (glutathione S-transferase, GST), that regulate apoptosis cell death (Caspase-3, Casp-3), and that facilitate neurotransmissions (cholinesterase-ChE). None of these enzyme systems is alone sufficient, but they act in concert to reduce the stress level of the organism. The interplay among enzymatic responses provides useful information on how organisms respond to environmental stressors acting on short time scales

Can space-for-time-substitution surveys represent zooplankton biodiversity patterns and their relationship to environmental drivers?

Space-for-Time-Substitution surveys (SFTS) are commonly used to describe zooplankton community dynamics and to determine lake ecosystem health. SFTS surveys typically combine single point observations from many lakes to evaluate the response of zooplankton community structure and dynamics (e.g., species abundance and biomass, diversity, demographics and modeled rate processes) to spatial gradients in hypothesized environmental drivers (e.g., temperature, nutrients, predation), in lieu of tracking such responses over long time scales. However, the reliability and reproducibility of SFTS zooplankton surveys have not yet been comprehensively tested against empirically-based community dynamics from longterm monitoring efforts distributed worldwide. We use a recently compiled global data set of more than 100 lake zooplankton time series to test whether SFTS surveys can accurately capture zooplankton diversity, and the hypothesized relationship with temperature, using simulated SFTS surveys of the time series data. Specifically, we asked: (1) to what degree can SFTS surveys capture observed biodiversity dynamics; (2) how does timing and duration of sampling affect detected biodiversity patterns; (3) does biodiversity ubiquitously increase with temperature across lakes, or vary by climate zone or lake type; and (4) do results from SFTS surveys produce comparable biodiversity-temperature relationship(s) to empirical data within and among lakes? Testing biodiversity-ecosystem function (BEF) relationships, and the drivers of such relationships, requires a solid data basis. Our work provides a global perspective on the design and usefulness of (long-term) zooplankton monitoring programs and how much confidence we can place in the zooplankton biodiversity patterns observed from SFTS surveys