Eclogite relics in the Variscan orogenic belt of Bulgaria (SE Europe)     

Laura Gaggero  Laura Buzzi  Ivan Haydoutov  Luciano Cortesogno 《International Journal of Earth Sciences》2009,98(8):1853-1877

Eclogitic rocks were sampled from two zones in the basement of the Sredna Gora terrane (central western Bulgaria): (1) partially retrogressed eclogites and amphibolites embedded in sillimanite-bearing garnet-micaschists with kyanite relics and migmatites and (2) banded amphibolites associated with muscovite-bearing metagranites within two-mica paragneisses. Rutile relics and oligoclase + green hornblende + epidote ± biotite pseudomorphs after garnet suggest an eclogite facies event. A tholeiitic, transitional affinity was determined for the protoliths, suggesting a continental rift environment, consistent with several eclogite-bearing complexes in the eastern segments of the Variscan belt that arose from the Cambro-Ordovician Gondwana break-up. Decreasing pressure after the eclogite overprint was demonstrated by (a) diopside-albite symplectite, and (b) plagioclase + red–brown to green amphibole kelyphite. The early static re-equilibration, dated to 398 ± 5.2 Ma by ⁴⁰Ar–³⁹Ar technique, was followed by an amphibolite facies foliation, which was pervasive in amphibolites, gneisses and micaschists, and poorly developed in eclogites. The lithospheric PT paths corresponding to higher and lower metamorphic gradients reflect the juxtaposition of crustal and lithospheric mantle units, respectively. In the build-up of the basement of the Balkan orogen, the physical properties of the lithological complexes might have influenced the collisional pattern of involved microplates.  相似文献   

Five years of thermal intra-urban monitoring in Florence (Italy) and application of climatological indices     

Martina Petralli  Luciano Massetti  Simone Orlandini 《Theoretical and Applied Climatology》2011,104(3-4):349-356

This paper presents 5?years of detailed intra-urban thermal measurements carried out in Florence (Italy) by a network of 25 air temperature stations. Daily, hourly, and degree-day indices were applied to hourly data to evaluate the difference within the complex urban environment of Florence. Stations were grouped in four clusters with similar thermal regimes in each season. Our results evidence a mean difference of almost 2°C between the hottest and the coolest cluster in all seasons. Furthermore, the coolest cluster had on average more than ten frost days in winter and the hottest cluster more than 12 summer days in summer. The intra-urban difference of tropical nights was even more evident, with values of 42 versus 10?days between the hottest and the coolest cluster during the summer period. The results of this study contribute to quantify the thermal intra-urban differences in the city of Florence, suggesting important applications in plant phenology, aerobiology, human health, urban planning, and biometeorology.  相似文献   

Rare earth and trace elements in igneous and high-temperature metamorphic minerals of oceanic gabbros (MARK area, Mid-Atlantic Ridge)     

Luciano Cortesogno  Laura Gaggero  Alberto Zanetti 《Contributions to Mineralogy and Petrology》2000,139(4):373-393

SIMS analyses have been carried out on clinopyroxenes, plagioclases and amphiboles of six gabbroic samples from Holes 921–924 of the Ocean Drilling Program Leg 153 sited in the MARK area of the Mid-Atlantic Ridge at the ridge–transform intersection, to investigate the rare earth, trace and volatile element distribution in the lower ocean crust during igneous crystallization and higher grade metamorphic conditions. The metagabbros underwent granulite to subgreenschist facies conditions through three main tectono-metamorphic phases: (1) ductile regime (750 < T < 1000 °C and P ≈ 0.3 GPa); (2) transitional regime (600 < T < 700 °C and P ≈ 0.2 GPa); (3) brittle regime (350 ≤ T < 600 °C and P < 0.2 GPa). Igneous clinopyroxenes show C1-chondrite normalized patterns depleted in LREE, and nearly flat for HREE. The rare earth and trace element distributions in igneous clinopyroxenes and plagioclases indicate that these minerals act as REE reservoirs, and comprise the main contribution to the overall rock content. The abundances in igneous minerals reflect the degree of fractionation of the parent liquids. In metamorphic clinopyroxenes recrystallized in anhydrous assemblages, the REE and trace elements patterns mimic those of the primary ones. Conversely, clinopyroxene re-equilibrated in amphibole-bearing assemblages shows a significant increase in REE, Ti, Zr, Y and V, a negative Eu anomaly, and slight decreases in Sr and Ba. An overall increase of REE and some trace elements is evident in hydrous assemblages, with preferential partitioning in the amphibole. It shows high Ti (18196–22844 ppm), LREE depleted patterns and La_N/Sm_N=0.10–0.33, La_N/Yb_N=0.10–0.30. Amphiboles from granoblastic assemblages show homogeneous patterns with no or a positive anomaly for Ti_N and negative anomalies for Sr_N and Zr_N. Volatiles in amphibole are low, with Cl/F < 1; H₂O% is significantly lower than the stoichiometric ratio (1.33–1.53%). The composition of the clinopyroxene and amphibole recrystallized in low-strain domains records evidence of incomplete re-equilibration, and element diffusion and partitioning is in part controlled by the textural site. The possible origins of the fluids involved in the metamorphic recrystallization are discussed: (1) remobilization from igneous amphibole; (2) exsolution from evolved melts; (3) introduction of seawater-derived fluids modified in rock-dominated systems; (4) injection of highly evolved hydrous melts during the metamorphic process. Received: 6 September 1999 / Accepted: 6 March 2000  相似文献   

Area usage estimation and spatiotemporal variability in distribution patterns of southern right whales,Eubalaena australis,of southern Brazil          下载免费PDF全文

Eduardo Pires Renault‐Braga  Karina Rejane Groch  Paulo A. de Carvalho Flores  Eduardo R. Secchi  Luciano Dalla‐Rosa 《Marine Ecology》2018,39(3)

Southern right whales—Eubalaena australis (Desmoulins, 1822)—migrate seasonally from high‐latitude feeding grounds to coastal breeding and calving grounds at lower latitudes such as the southern coast of Brazil. Understanding how these whales are distributed along the coast is important for monitoring their postwhaling recovery and defining management strategies. In this study, we applied Kernel density estimators to aerial survey data to determine main occurrence and concentration areas of right whales in southern Brazil and investigate inter‐ and intra‐annual distribution patterns between 2003 and 2012. Our results show considerable variation in area usage within and among years, and changes in the general distribution pattern of right whales in the last years of the study. Intra‐annually, higher concentration area tended to expand from July to September and decrease in November. Some areas stood out as high‐density areas for right whales: Ribanceira/Ibiraquera, Itapirubá Sul/Sol, and from Arroio to Gaivota. Some evidences also suggest preferential areas for mother–calf pairs. The higher concentration area of right whales in southern Brazil was estimated at 52,541 km² and the occurrence area was 682.69 km², which is the whole study area. As right whale distribution in the region is likely expanding due to this population's current recovery, our study provides essential information for management plan of the Right Whale Environmental Protection Area.  相似文献   

On Flare-CME Characteristics from Sun to Earth Combining Remote-Sensing Image Data with <Emphasis Type="Italic">In Situ</Emphasis> Measurements Supported by Modeling     

Manuela Temmer  Julia K. Thalmann  Karin Dissauer  Astrid M. Veronig  Johannes Tschernitz  Jürgen Hinterreiter  Luciano Rodriguez 《Solar physics》2017,292(7):93

We analyze the well-observed flare and coronal mass ejection (CME) from 1 October 2011 (SOL2011-10-01T09:18) covering the complete chain of effects – from Sun to Earth – to better understand the dynamic evolution of the CME and its embedded magnetic field. We study in detail the solar surface and atmosphere associated with the flare and CME using the Solar Dynamics Observatory (SDO) and ground-based instruments. We also track the CME signature off-limb with combined extreme ultraviolet (EUV) and white-light data from the Solar Terrestrial Relations Observatory (STEREO). By applying the graduated cylindrical shell (GCS) reconstruction method and total mass to stereoscopic STEREO-SOHO (Solar and Heliospheric Observatory) coronagraph data, we track the temporal and spatial evolution of the CME in the interplanetary space and derive its geometry and 3D mass. We combine the GCS and Lundquist model results to derive the axial flux and helicity of the magnetic cloud (MC) from in situ measurements from Wind. This is compared to nonlinear force-free (NLFF) model results, as well as to the reconnected magnetic flux derived from the flare ribbons (flare reconnection flux) and the magnetic flux encompassed by the associated dimming (dimming flux). We find that magnetic reconnection processes were already ongoing before the start of the impulsive flare phase, adding magnetic flux to the flux rope before its final eruption. The dimming flux increases by more than 25% after the end of the flare, indicating that magnetic flux is still added to the flux rope after eruption. Hence, the derived flare reconnection flux is most probably a lower limit for estimating the magnetic flux within the flux rope. We find that the magnetic helicity and axial magnetic flux are lower in the interplanetary space by ～?50% and 75%, respectively, possibly indicating an erosion process. A CME mass increase of 10% is observed over a range of \({\sim}\,4\,\mbox{--}\,20~\mathrm{R}_{\odot }\). The temporal evolution of the CME-associated core-dimming regions supports the scenario that fast outflows might supply additional mass to the rear part of the CME.  相似文献   

List of papers from other journals     

Luciano Baresi  Sebastiano Colazzo  Luca Mainetti  Sandro Morasca 《Solar physics》1991,136(2):395-406

List of papers from other journals  相似文献   

Setting-up local “mapping geoids” with the aid of GPS/LEV traverses. Application to the geoids of Sardinia and Calabria     

Giuseppe Birardi  Domenico Santarsiero  Donato Tufillaro  Luciano Surace 《Journal of Geodesy》1995,70(1-2):98-109

The problem of fitting a pre-existing geoid on local GPS/LEV points is first taken into account, a possible way for its solution is proposed, based on techniques similar to the aerophotogrammetric absolute orientation.This approach is then used to compute themapping geoids of Sardinia and Calabria i.e. geoids with decimetric accuracy, needed for the heigthing of large scale maps. The pre-existing geoids EAGGI by Brennecke et al. (1983), and EGG2 by Denker et al (1993) are utilized, fitted on points of GPS/LEV traverses.The complete input-output data, the contour maps of both geoids, and a substantial checking on some Calabrian GPS/TRIG points of the entreprise IGM.95 are finally reported.  相似文献   

Phosphorus metabolism in anthropogenically transformed lagoon ecosystems: The Comacchio lagoons (Ferrara, Italy)     

Yuri I. Sorokin  Franco Dallocchio  Fernando Gelli  Luciano Pregnolato 《Journal of Sea Research》1996,35(4):243-250

Inorganic phosphorus dynamics were investigated with the use of ³²P in the hypertrophic Comacchio lagoons (NE Adriatic) during an extremely dense, quasi-permanent bloom of picocyanobacteria. Concentrations of dissolved inorganic phosphate (DIP) in waters of the blooming lagoons were usually near the detection limit (0.01 μmoles·dm⁻³). DIP uptake rates by microplankton at near-ambient concentrations (0.01 to 0.1 μmoles·dm⁻³) were in the range of 9.6 to 16.1 nmoles P·dm⁻³·min⁻¹, and turnover times were 1.5 to 3 min. The turnover time was >40 h in the eutrophic coastal waters of the adjacent Adriatic Sea. The uptake rate of DIP depended on its initial concentration. In water samples artificially enriched with DIP, the uptake rate rose to its maximum of 0.10 to 0.13 μmoles P·dm⁻³·min⁻¹ (or 6 to 7 μmoles·dm⁻³·h⁻¹) when the initial concentration of DIP was elevated to 10 to 20 μmoles·dm⁻³. The potential capacity of microplankton in the water samples to consume and retain DIP was estimated at 25 μmoles·dm⁻³. Specific features are discussed of phosphorus metabolism in the anthropogenically transformed lagoon ecosystem with an anomalous food web with few animals.  相似文献   

Search for radio pulsations in four anomalous X-ray pulsars and discovery of two new pulsars     

Marta Burgay  Nanda Rea  GianLuca Israel  Andrea Possenti  Luciano Burderi  Tiziana Di Salvo  Nichi D’Amico  Luigi Stella  Elisa Nichelli 《Astrophysics and Space Science》2007,308(1-4):531-534

We have performed deep searches for radio pulsations from four southern anomalous X-ray pulsars (AXPs) to investigate their physical nature in comparison with the rotation powered pulsars. The data were acquired using the Parkes radio telescope with the 1.4 GHz multibeam receiver. No pulsed emission with periodicity matching the X-ray ephemeris have been found in the observed targets down to a limit of ∼0.1 mJy. A blind search has also been performed on all the 13 beams of the multibeam receiver (the central beam being pointed on the target AXP), leading to the serendipitous discovery of two new radio pulsars and to the further detection of 18 pulsars. Also a search for single dispersed pulses has been performed in the aim to detect signals similar to those of the recently discovered rotating radio transients.   相似文献   

Mass and interior of Enceladus from Cassini data analysis     

Nicole J. Rappaport  Luciano Iess  Aseel Anabtawi  Lucia Somenzi 《Icarus》2007,190(1):175-178

Gravity results are available from radio Doppler data acquired by the Deep Space Network during the encounter of the Cassini spacecraft with Enceladus in February 2005. We report the mass of Enceladus to be (1.0798±0.0016)×¹⁰²⁰ kg, which implies a density of . For a core made of hydrated silicates with a density of 2500 kg m⁻³ the core radius is ∼190 km and the quadrupole moment C₂₂∼1.4×¹⁰⁻³. If Enceladus is in hydrostatic equilibrium, the larger than previously anticipated density implies that the recently proposed secondary spin-orbit resonance cannot be present. Therefore, the source of endogenic activity of Enceladus remains unexplained.  相似文献