Amphipoda assemblages in a disturbed area (Alicante,Spain, Western Mediterranean)

The distribution and composition of Amphipoda assemblages were analysed off the coasts of Alicante (Spain, Western Mediterranean), a disturbed area affected by several co‐occurring anthropogenic impacts. Although differences among sampled stations were mainly related to natural parameters, anthropogenic activities were linked with changes in amphipod assemblages. Expansion of the Port of Alicante, a sewage outfall and a high salinity brine discharge could be causing the disappearance of amphipods at stations closer to these disturbances. However, the completion of port enlargement works and mitigatory dilution of the brine discharge has led to the recovery of the amphipod assemblage. Among the natural parameters, depth determines the distribution of some of the species. While Siphonoecetes sabatieri was abundant at shallow stations, Ampelisca spp., Photis longipes, Pseudolirius kroyeri, Apherusa chiereghinii and Phtisica marina were more abundant at deeper stations. Grain size and percentage of organic matter also influenced amphipod distribution, resulting in changes in species composition and in the relative percentages of different trophic groups. Species such as Ampelisca brevicornis, Perioculodes longimanus, Urothoe hesperiae and Urothoe elegans were more abundant at stations with a high content of fine sand. Carnivorous species, mainly of the Oedicerotidae family, were more abundant at those stations with a low organic matter content, while detritivorous species were more abundant at stations with a higher mud content. Among 62 identified species, three were reported for the first time from the Spanish Mediterranean coast, two species were recorded for the second time and a new species of Siphonoecetes was found, Siphonoecetes (Centraloecetes) bulborostrum. These results confirm the need for further data on amphipods from the Mediterranean Spanish coast.     

INTEGRAL/RXTE high-energy observation of a state transition of GX 339–4

On 2004 August 15, we observed a fast (shorter than 10 h) state transition in the bright black hole transient GX 339–4 simultaneously with Rossi X-Ray Timing Explorer ( RXTE ) and INTEGRAL . This transition was evident both in timing and spectral properties. Combining the data from the Proportional Counter Array (PCA), the High-Energy X-ray Timing Experiment (HEXTE) and the Imager on Board the INTEGRAL Satellite (IBIS), we obtained good quality broad-band (3–200 keV) energy spectra before and after the transition. These spectra indicate that the hard component steepened. Also, the high-energy cut-off that was present at ∼70 keV before the transition was not detected after the transition. This is the first time that an accurate determination of the broad-band spectrum across such a transition has been measured on a short time-scale. It shows that, although some spectral parameters do not change abruptly through the transition, the high-energy cut-off increases/disappears rather fast. These results constitute a benchmark on which to test theoretical models for the production of the hard component in these systems.     

The EVE Doppler Sensitivity and Flare Observations

The Extreme-ultraviolet Variability Experiment (EVE; see Woods et al., 2009) obtains continuous EUV spectra of the Sun viewed as a star. Its primary objective is the characterization of solar spectral irradiance, but its sensitivity and stability make it extremely interesting for observations of variability on time scales down to the limit imposed by its basic 10 s sample interval. In this paper we characterize the Doppler sensitivity of the EVE data. We find that the 30.4 nm line of He ii has a random Doppler error below 0.001 nm (1 pm, better than 10 km s⁻¹ as a redshift), with ample stability to detect the orbital motion of its satellite, the Solar Dynamics Observatory (SDO). Solar flares also displace the spectrum, both because of Doppler shifts and because of EVE’s optical layout, which (as with a slitless spectrograph) confuses position and wavelength. As a flare develops, the centroid of the line displays variations that reflect Doppler shifts and therefore flare dynamics. For the impulsive phase of the flare SOL2010-06-12, we find the line centroid to have a redshift of 16.8 ± 5.9 km s⁻¹ relative to that of the flare gradual phase (statistical errors only). We find also that high-temperature lines, such as Fe xxiv 19.2 nm, have well-determined Doppler components for major flares, with decreasing apparent blueshifts as expected from chromospheric evaporation flows.     

Dependence of clinopyroxene composition on cooling rate in basaltic magmas: Implications for thermobarometry

The compositional variation of clinopyroxene and the partitioning of major elements between clinopyroxene and melt are estimated as a function of the cooling rate. Clinopyroxenes were crystallized under variable cooling regimes (15, 9.4, 3, 2.1, and 0.5 °C/min from 1250 down to 1000 °C) and at isothermal conditions of 1000 °C from a basaltic composition at a pressure of 500 MPa under anhydrous and hydrous (H₂O = 1.3 wt.%) conditions. The clinopyroxene chemistry shows that, as the cooling rate increases, crystals are progressively depleted in Ca, Mg, Fe²⁺ and Si and enriched in Na, Fe³⁺, Al (mainly Al^IV), and Ti. Di and Hd versus CaTs and CaFeTs form a continuous binary solid solution characterized by higher amounts of tschermakitic components with increasing cooling rate. Two parameters (DH = Di + Hd and TE = CaTs + CaFeTs + En) are calculated to describe the effect of cooling rate on the clinopyroxene composition. The variation of DH/TE with increasing cooling rate evidences the kinetic process induced by rapid cooling in basic rocks under hydrous and anhydrous conditions.Dynamic crystallization conditions affect the partitioning of major elements between clinopyroxene and melt; with increasing cooling rate, the value of crystal–melt partition coefficient departs from that obtained at the isothermal condition. However, in spite of these variations, the values of ^cpx–meltKd_Fe–Mg remain almost constant. Therefore, the Fe²–Mg exchange between clinopyroxene and melt is not suitable to prove the (dis)equilibrium conditions in basaltic cooling magmas, giving rise to possible mismatches in the application of thermobarometers. The results of our study are consistent with that observed at the margin of dikes or in the exterior portions of lavas, where the cooling rate is maximized and disequilibrium compositions of clinopyroxene have been found.     

New Cretaceous paleomagnetic results from the foreland of the Southern Alps and the refined apparent polar wander path for stable Adria

The central-western and the eastern Southern Alps are separated by the triangular shaped Adige embayment, which belongs to stable Adria and was the site of pelagic sedimentation from the Tithonian through Maastrichtian. The first part of this study presents paleomagnetic results from the Tithonian–Cenomanian Biancone and Turonian–Maastrichtian Scaglia Rossa formations sampled at 33 geographically distributed and biostratigraphically dated localities.The new and high quality paleomagnetic results from the Adige embayment are then combined with coeval paleomagnetic directions from autochthonous Istria (Márton et al., 2008), which also belongs to stable Adria. The combined data set (which for the Late Albian–Maastrichtian time period is constructed similarly to the synthetic African curve by Besse and Courtillot, 2002, 2003) reveals an important tectonic event (Late Aptian–Early Albian) characterized by 20° CCW rotation and sedimentary hiatus.Comparison between paleomagnetic declinations/inclinations expected in an African framework (i.e. with the assumption that Adria is still an African promontory) leads to the following conclusions. The time-distributed Tithonian and Berriasian (150–135 Ma) paleomagnetic directions exhibit the “African hairpin” with an inclination minimum and a sudden change from CW to CCW rotation at 145 Ma. Concerning the younger ages, the declinations for Adria continue to follow the African trend of CCW rotation till the end of Cretaceous. However, the Tithonian–Maastrichtian declination curve for stable Adria is displaced by 10° from the “African” curve as a result of two rotations. The first, an about 20° CW rotation of Adria with respect to Africa took place between the Maastrichtian and the mid-Eocene. During this time the orientation of Adria remained the same, while Africa continued its CCW rotation. The younger rotation (30°CCW) changed the orientation of Adria relative to Africa as well as to the present North.     

Rapid estimation of ground-shaking maps for seismic emergency management in the Campania Region of southern Italy

Strong ground-shaking mapping soon after a moderate-to-large earthquake is crucial to recognize the areas that have suffered the largest damage and losses. These maps have a fundamental role for emergency services, loss estimation and planning of emergency actions by the Civil Protection Authorities. This is particularly important for areas with high seismic risk levels, such as the Campania-Lucania Region in southern Italy. Taking advantage of the Irpinia Seismic Network (ISNet), a recently installed dense and wide dynamic seismic network, we have developed a procedure for rapid estimation of ground-shaking maps after moderate-to-large earthquakes (GRSmap). This uses an optimal data gridding scheme designed to account for bi-dimensional features of strong ground-motion fields, such as directivity, radiation patterns and focal mechanisms, to which most damage can be correlated. The basis of the mapping technique is a triangulation procedure to locally correct predicted data at the triangle barycentres where their vertices correspond to seismic stations. The method has been tested off-line using a simulated M 6.6 earthquake located at the centre of ISNet and applied to data of the 23 November 1980 Irpina M 6.9 earthquake recorded by a sparse network. This has highlighted its ability to predict peak ground-motion parameters of large magnitude earthquakes with respect to the attenuation relationships.     

Non-ENSO interannual rainfall variability in central Chile during austral winter

The first principal component (PC1) of seasonal rainfall anomalies in central Chile during winter (June–August) is used to analyze the circulation anomalies related to wet and dry conditions, when near-normal or neutral SST anomalies are observed in the equatorial Pacific, i.e., during non-ENSO conditions. Eight wet and eight dry winter seasons were defined as the upper and lower terciles of PC1 for 24 non-ENSO winters in the period 1958–2000. Unlike the single process attributed to ENSO, during non-ENSO winter seasons, there are several sources triggering or modifying the propagation of the stationary waves that impact the rainfall regime in central Chile. Unfortunately, the multiple processes that seem to be involved in the modulation of the interannual rainfall variability in central Chile, as seen in this work, limit the predictability of rainfall during non-ENSO conditions.     

Cooling and exhumation history of deep‐seated and shallow level,late Hercynian granitoids from Calabria

The thermal and exhumation history of late Hercynian granitoids from Calabria (Sila and Serre massifs) has been studied using thermobarometry and radiometric age determinations. The uplift and erosion which followed contractional tectonics of Tertiary age exposed in Calabria a nearly complete section of the Hercynian crust. Field data, constrained by igneous thermobarometrical data, have enabled us to draw simplified crustal profiles. In both the Sila and Serre massifs, granitoids make up the intermediate portions of the crustal sections and are stacked as tabular intrusions for up to 13 km cumulative thickness. Shallow granitoids are characterized by a weak fabric, mostly developed in the magmatic stage, whereas deep‐seated granitoids display a strong fabric developed in the magmatic state and, with decreasing temperatures, in the subsolidus state. The intrusive bodies were emplaced at 300–290 Ma, at a time when the Calabrian crust was undergoing extensional tectonics and crustal thinning. The subsequent post‐Hercynian evolution is recorded by Rb‐Sr dates of micas and fission track ages of zircon and apatite obtained from granitoids emplaced at different depths. A decrease in Rb‐Sr and fission track ages is observed as depth of emplacement increases. Data on the post‐Hercynian geological evolution of Calabria were used to model in three stages the cooling and exhumation history of deep‐seated and shallow granitoids. The first stage, in Permian to Triassic times, was characterized by slow erosion. It was followed by a second stage of extensional tectonics in Jurassic times. The third stage was exhumation during the Apenninic Orogeny. The model has generated two P–T–t arrays, one for deep‐seated and the other for shallow granitoids of the Serre massif. The T–t paths suggest that the dates of micas, zircon and apatite are cooling ages. They also show that deep‐seated granitoids remained at temperatures above the brittle–plastic transition for a long time, whereas shallow granitoids cooled rapidly. Distinct P–T–t paths explain why deep‐seated and shallow granitoids display different fabric and microstructural features. Copyright © 2000 John Wiley & Sons, Ltd.     

Petrology of basic and intermediate orogenic granitoids from the Sila Massif (Calabria,southern Italy)

Hercynian gabbroic, dioritic and tonalitic rocks crop out in the neighbourhood of Rovale (Sila Grande, Calabria). They make up a crude rectangular outcrop with the western part consisting of gabbroic rocks and the eastern of dioritic and tonalitic rocks. They come into contact with medium to high grade metapelites on the western side and with heterogeneous granodiorites on the other sides. In the gabbroic body both opx ± ol bearing cumulates and amphibole differentiates occur and are characterized by the widespread presence of brown pargasite. Sporadic magmatic to subsolidus corona textures between olivine and plagioclase or orthopyroxene and plagioclase can be observed and their preservation clearly suggests a post-tectonic emplacement for the gabbroic magma. Diorites and tonalites display hypidiomorphic textures free of olivine and orthopyroxene and bearing green Mg-hornblende. The granitoids, on the basis of chemical data, display orogenic features of the continent-continent collision type. The gabbroic rocks have high Al tholeiitic composition and fractionation of orthopyroxene and plagioclase played an important part in their evolution. The Rb/Sr isochron method did not give a precise emplacement age for the granitoids as a whole. Initial ⁸⁷Sr/⁸⁶Sr ratios (at 290 Ma) are higher in the gabbroic body (0.7091–0.7095) than in diorites and tonalites (0.7083–0.7092). Thus gabbroic rocks appear more displaced than diorites and tonalites towards crustal isotopic composition. The eNd data seem to confirm this feature, thus suggesting that the gabbroic rocks and diorites derived from distinct mantle magma batches. Interestingly, small isotropic gabbroic masses occur within the diorites and show general features that allow them to be considered as possibly parental with respect to the host diorites. The evolution to the dioritic composition might have occurred through fractionation and minor mixing with a more acidic component such as the northern granodiorites. Geochemical, Sr and Nd isotopic data indicate a scenario of a composite plutonic body formed by distinct magma batches of mixed crust and mantle origin.