Lithostratigraphy and U-Pb zircon dating in the overturned limb of the Siviez-Mischabel nappe: a new key for Middle Penninic nappe geometry.

Detailed field work and zircon analysis have improved the knowledge of the lithostratigraphy at the base of the Siviez-Mischabel nappe in the Mattertal (St-Niklaus-Törbel area). They confirm the existence of an overturned limb and clarify the structure of the St-Niklaus syncline. The following formations can be observed:

• Polymetamorphic gneisses; composed of paragneisses, amphibolites and micaschists (Bielen Unit, pre-Ordovician).
• Fine-grained, greyish quartzite and graywacke with kerogen-rich horizons (Törbel Formation, presumed Carboniferous).
• Green or white micaschists characterized by brown carbonate spots associated with white conglomeratic quartzites (Moosalp Formation, Early Permian).
• Massive, green or white, fine grained, microconglomeratic or conglomeratic quartzites with characteristic pink quartz pebbles (Bruneggjoch Formation, Late Permian-Early Triassic).

This coherent overturned sequence can be observed from the St-Niklaus area to the Moosalp pass to the north. Detailed mapping revealed that the St-Niklaus syncline is symmetrical and connects the overturned limb of the Siviez-Mischabel nappe to the normal series of the Upper Stalden zone. U-Pb zircon geochronology on magmatic and detrital zircons allowed constraining ages of these formations. Detrital zircons display ages ranging from 2900 ± 50 to 520 ± 4 Ma in the Törbel Formation, and from 514 ± 6 to 292 ± 9 Ma in the Moosalp Formation. In addition, the Permian Randa orthogneiss is intrusive into the polymetamorphic gneisses and into the Permo-Carboniferous metasediments of the overturned limb of the Siviez-Mischabel nappe. This revision clarified also the lithostratigraphy of the nearby and subjacent Lower Stalden zone composed of an overturned limb with Permo-Carboniferous formations. This has critical implications for the tectonic setting of the nappes in the region, speaking for few recumbent folds with well preserved normal and overturned limbs instead of a succession of imbricate thrust sheets in a normal stratigraphic position.     

Basic physiological biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)

By measuring a battery of basic physiological biomarkers and the concentration of SigmaDDT in adult female perch (Perca fluviatilis), an assumed aquatic pollution gradient was confirmed, with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included an upstream gradient, westwards through Lake M?laren (46 km), and a downstream gradient, eastwards through the Stockholm archipelago (84 km). The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch: retarded growth, increased frequency of sexually immature females, low gonadosomatic index, and disturbed visceral fat metabolism. SigmaDDT, measured as a pollution indicator, was 10-28 times higher than the background in perch from the Baltic Proper. Besides the main gradient other sources of pollution also influenced the response pattern of the measured biomarkers. In particular, there were strong indications of pollution coming from the Baltic Sea.     

Shock experiments in range of 10–45 GPa with small multidomain magnetite in porous targets

Abstract– Physical properties of multidomain magnetite‐bearing porous pellets shocked up to 45 GPa were measured. The results show general magnetic softening as a result of shock. However, a relative magnetic hardening trend and slight magnetic susceptibility decrease is observed with increasing pressure among shocked samples. Initially, the shock also seems to cause a slight decrease in porosity, but at higher shock pressures macroscopic porosity increases progressively in our pellets. The microscopic porosity remains almost unchanged. Since our samples have distinctly higher initial porosity compared with samples used in previous studies, our results may be representative for impacts into highly porous magnetite‐bearing sedimentary or volcanic rocks and are relevant to impacts into such target rocks on Earth and Mars.     

Petrology and zircon U–Pb dating of well‐preserved eclogites from the Thongmön area in central Himalaya and their tectonic implications

The discovery of eclogites is reported within the Great Himalayan Crystalline Complex in the Thongmön area, central Himalaya, and their metamorphic evolution is deciphered by petrographic studies, pseudosection modelling, and zircon dating. For the first time, omphacite has been found in the matrix of eclogites taken from a metamorphic mafic lens. Two groups of garnet have been identified in the Thongmön eclogites on the basis of major and rare earth elements and mineral inclusions. Core and intermediate sections of garnet represent Grt I, in which the major elements (Ca, Mg, and Fe) show a nearly homogenous distribution with little or weak zonation. This Grt I displays an almost flat chondrite‐normalized HREE pattern, and the main inclusions are amphibole, apatite, quartz, and abundant omphacite. Grt II, forms thin rims on large garnet grains, and is characterized by rim‐ward Ca decrease and Mg increase and MREE enrichment relative to HREE and LREE. No amphibole inclusions are found in Grt II, indicating the decomposition of amphibole contributed to its MREE enrichment. Two metamorphic stages, recorded by matrix minerals and inclusions in garnet and zircon, outline the burial of the Thongmön eclogites and progressive metamorphic processes to the pressure peak: (a) the assemblage of amphibole–garnet–omphacite–phengite–rutile–quartz, with the phengite interpreted as having been replaced by Bt+Pl symplectites, represents the prograde amphibole eclogite facies stage M1₍₁₎, (b) in the peak eclogite facies [stage M1₍₂₎], amphibole was lost and melting started. Based on the compositions of garnet and omphacite inclusions, M1₍₁₎ is constrained to 19–20 kbar and 640–660°C and M1₍₂₎ occurred at >21 kbar, >750°C, with appearance of melt and its entrapment in metamorphic zircon. SHRIMP U–Pb dating of zircon from two eclogite samples yielded consistent metamorphic ages of 16.7 ± 0.6 Ma and 17.1 ± 0.4 Ma respectively. The metamorphic zircon grew concurrently with Grt II in the peak eclogite facies. Thongmön eclogites characterized by the prograde metamorphism from amphibolite facies to eclogite facies were formed by the continuing continental subduction of Indian plate beneath the Euro‐Asian continent in the Miocene.     

Assessing Collaborative Conservation: A Case Survey of Output,Outcome, and Impact Measures Used in the Empirical Literature

Abstract

Much existing research on collaborative conservation has focused on process, even as researchers have called for greater attention to explaining what results these processes yield. It is time to take stock of collaborative conservation research by mapping what kinds of variables researchers are including in analyses. Here we conduct a case survey from the SCAPE database of environmental decision-making cases. We include cases involving collaboration across government, environmental protection, and resource exploitation interests in western democratic countries. Results reveal patterns in what researchers include in their outputs, outcomes, and impacts measures of collaborative conservation. While there is little difference by publication type (peer-reviewed journals, scholarly book chapters, or gray literature) or over time, we find significant differences in explicit measures across variable types. In particular, variables more proximate to process in a logic chain are more often measured, as are social rather than ecological variables.     

The tidal and wind induced hydrodynamics of the composite system Adriatic Sea/Lagoon of Venice

A shallow water hydrostatic 2D hydrodynamic numerical model, based on the boundary conforming coordinate system, was used to simulate aspects of both general and small scale oceanic features occurring in the composite system constituted by the Adriatic Sea and the Lagoon of Venice (Italy), under the influence of tide and realistic atmospheric forcing. Due to a specific technique for the treatment of movable lateral boundaries, the model is able to simulate efficiently dry up and flooding processes within the lagoon. Firstly, a model calibration was performed by comparing the results of the model, forced using tides and ECMWF atmospheric pressure and wind fields, with observations collected for a set of 33 mareographic stations uniformly distributed in the Adriatic Sea and in the Lagoon of Venice. A second numerical experiment was then carried out by considering only the tidal forcing. Through a comparison between the results obtained in the two experiments it was possible to assess the reliability of the estimated parameter through the composite forcing. Model results were then verified by comparing simulated amplitude and phase of each tidal constituent as well as tidal velocities simulated at the inlets of the lagoon and in the Northern Adriatic Sea with the corresponding observed values. The model accurately reproduces the observed harmonics: mean amplitude differences rarely exceed 1 cm, while phase errors are commonly confined below 15°. Semidiurnal and diurnal currents were correctly reproduced in the northern basin and a good agreement was obtained with measurements carried out at the lagoon inlets. On this basis, the outcomes of the hydrodynamic model were analyzed in order to investigate: (i) small-scale coastal circulation features observed at the interface between the adjoining basins, which consist often of vortical dipoles connected with the tidal flow of Adriatic water entering and leaving the Lagoon of Venice and with along-shore current fields connected with specific wind patterns; (ii) residual oscillations, which are often connected to meteorological forcing over the basin. In particular, it emerges that small-scale vortical features generated near the lagoon inlet can be efficiently transported toward the open sea, thus contributing to the water exchange between the two marine regions, and a realistic representation of observed residual oscillations in the area would require a very detailed knowledge of atmospheric as well as remote oceanic forcing.