Compound ultrarefractory CAI‐bearing inclusions from CV3 carbonaceous chondrites     

Marina A. IVANOVA  Alexander N. KROT  Kazuhide NAGASHIMA  Glenn J. MacPHERSON 《Meteoritics & planetary science》2012,47(12):2107-2127

Two compound calcium‐aluminum‐rich inclusions (CAIs), 3N from the oxidized CV chondrite Northwest Africa (NWA) 3118 and 33E from the reduced CV chondrite Efremovka, contain ultrarefractory (UR) inclusions. 3N is a forsterite‐bearing type B (FoB) CAI that encloses UR inclusion 3N‐24 composed of Zr,Sc,Y‐rich oxides, Y‐rich perovskite, and Zr,Sc‐rich Al,Ti‐diopside. 33E contains a fluffy type A (FTA) CAI and UR CAI 33E‐1, surrounded by Wark‐Lovering rim layers of spinel, Al‐diopside, and forsterite, and a common forsterite‐rich accretionary rim. 33E‐1 is composed of Zr,Sc,Y‐rich oxides, Y‐rich perovskite, Zr,Sc,Y‐rich pyroxenes (Al,Ti‐diopside, Sc‐rich pyroxene), and gehlenite. 3N‐24’s UR oxides and Zr,Sc‐rich Al,Ti‐diopsides are ¹⁶O‐poor (Δ¹⁷O approximately ?2‰ to ?5‰). Spinel in 3N‐24 and spinel and Al‐diopside in the FoB CAI are ¹⁶O‐rich (Δ¹⁷O approximately ?23 ± 2‰). 33E‐1’s UR oxides and Zr,Sc‐rich Al,Ti‐diopsides are ¹⁶O‐depleted (Δ¹⁷O approximately ?2‰ to ?5‰) vs. Al,Ti‐diopside of the FTA CAI and spinel (Δ¹⁷O approximately ?23 ± 2‰), and Wark‐Lovering rim Al,Ti‐diopside (Δ¹⁷O approximately ?7‰ to ?19‰). We infer that the inclusions experienced multistage formation in nebular regions with different oxygen‐isotope compositions. 3N‐24 and 33E‐1’s precursors formed by evaporation/condensation above 1600 °C. 3N and 33E’s precursors formed by condensation and melting (3N only) at significantly lower temperatures. 3N‐24 and 3N’s precursors aggregated into a compound object and experienced partial melting and thermal annealing. 33E‐1 and 33E avoided melting prior to and after aggregation. They acquired Wark‐Lovering and common forsterite‐rich accretionary rims, probably by condensation, followed by thermal annealing. We suggest 3N‐24 and 33E‐1 originated in a ¹⁶O‐rich gaseous reservoir and subsequently experienced isotope exchange in a ¹⁶O‐poor gaseous reservoir. Mechanism and timing of oxygen‐isotope exchange remain unclear.  相似文献   

Correction to: Observations of a Radio-Quiet Solar Preflare     

Arnold O. Benz  Marina Battaglia  Manuel Güdel 《Solar physics》2018,293(2):32

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Landslide susceptibility mapping by remote sensing and geomorphological data: case studies on the Sorrentina Peninsula (Southern Italy)     

Claudia Spinetti  Marina Bisson  Cristiano Tolomei  Laura Colini  Alessandro Galvani  Marco Moro 《地理信息系统科学与遥感》2019,56(6):940-965

The Sorrentina Peninsula is a densely populated area with high touristic impact. It is located in a morphologically complex zone of Southern Italy frequently affected by dangerous and calamitous landslides. This work contributes to the prevention of such natural disasters by applying a GIS-based interdisciplinary approach aimed to map the areas more potentially prone to trigger slope instability phenomena. We have developed the Landslide Susceptibility Index (LSI) combining five weighted and ranked susceptibility parameters on a GIS platform. These parameters are recognized in the literature as the main predisposing factors for triggering landslides. This work combines analyses conducted on Remote Sensing, Geo-Lithology and Morphometry data and it is organized in the following logical steps: i) Multi-temporal InSAR technique was applied to Envisat-ASAR (2003–2010) and COSMO-SkyMed (2013–2015) datasets to obtain the ground displacement time series and the relative mean ground velocity maps. InSAR allowed the detection of the areas that are subjected to ground deformation and the main affected municipalities; ii) Such deformation areas were investigated through airborne photo interpretation to identify the presence of geomorphological peculiarities connected to potential slope instability. Subsequently, some of these peculiarities were checked on the field; iii) In these deformation areas the susceptibility parameters were mapped in the entire territory of Amalfi and Conca dei Marini and then investigated with a multivariate analysis to derive the classes and the respective weights used in the LSI calculation. The resulting LSI map classifies the two municipalities with high spatial resolution (2m) according to five classes of instability. The map highlights that the high/very high susceptibility zones cover 6% of the investigated territory and correspond to potential landslide source areas characterized by 25°-70° slope angles. A spatial analysis between the map of the historical landslides and the areas classified according to susceptibility allowed testing of the reliability of the LSI Index, resulting in 85% prediction accuracy.  相似文献   

Ardières-Morcille in the Beaujolais,France: A research catchment dedicated to study of the transport and impacts of diffuse agricultural pollution in rivers     

Véronique Gouy  Lucie Liger  Samira Ahrouch  Chloé Bonnineau  Nadia Carluer  Arnaud Chaumot  Marina Coquery  Aymeric Dabrin  Christelle Margoum  Stéphane Pesce 《水文研究》2021,35(10):e14384

The 8-km² Morcille catchment, which is a sub-catchment of the 150-km² Ardières catchment in the Beaujolais region of France, is one of the first sites in Europe where research has been conducted on surface water contamination by pesticides. A consolidated hydrological and chemical dataset has been set up with data collected since 2002 on the Morcille River and since 2011 on the Ardières River. Additional data on the ecotoxicological and ecological impacts of pesticides on aquatic microbial communities and macroinvertebrates has also been recorded in both rivers since 2005. The ‘Site Atelier Ardières-Morcille Dataset’ described here combines rainfall and stream water height measurements at gauged stations with concentrations of two trace elements and nine pesticides (mainly herbicides, fungicides and some of their metabolites) in both the Ardières and Morcille rivers. All contaminant concentration data showed spatial and temporal variability in water quality associated with pesticide use and rainfall patterns. This long-term monitoring framework made it possible to estimate the persistence of two herbicides (diuron and norflurazon) after legislation banning them. It took 4 years for diuron and more than 10 years for norflurazon concentrations to fall below 0.1 μg/L. Concurrent biological data showed a gradient of impacts consistent with chemical anthropogenic pressure, and rapid recovery of phototrophic microbial communities after the diuron ban. Finally, monitoring data on pesticide transport in a grassed strip set on a slope of the Morcille catchment confirmed that vegetative filter strips can effectively reduce diuron fluxes in surface runoff (>80% abatement) and infiltration water (>70% abatement). The full dataset offers a valuable resource for the validation of hydrological models and the development of global approaches to better understand the pressure–transport–exposure–impact chain and aquatic community resilience at the small catchment scale.  相似文献   

Coupling eruption and tsunami records: the Krakatau 1883 case study,Indonesia     

Raphaël Paris  Patrick Wassmer  Franck Lavigne  Alexander Belousov  Marina Belousova  Yan Iskandarsyah  Mhammed Benbakkar  Budianto Ontowirjo  Nelly Mazzoni 《Bulletin of Volcanology》2014,76(4):1-23

The well-documented 1883 eruption of Krakatau volcano (Indonesia) offers an opportunity to couple the eruption’s history with the tsunami record. The aim of this paper is not to re-analyse the scenario for the 1883 eruption but to demonstrate that the study of tsunami deposits provides information for reconstructing past eruptions. Indeed, though the characteristics of volcanogenic tsunami deposits are similar to those of other tsunami deposits, they may include juvenile material (e.g. fresh pumice) or be interbedded with distal pyroclastic deposits (ash fall, surges), due to their simultaneity with the eruption. Five kinds of sedimentary and volcanic facies related to the 1883 events were identified along the coasts of Java and Sumatra: (1) bioclastic tsunami sands and (2) pumiceous tsunami sands, deposited respectively before and during the Plinian phase (26–27 August); (3) rounded pumice lapilli reworked by tsunami; (4) pumiceous ash fall deposits and (5) pyroclastic surge deposits (only in Sumatra). The stratigraphic record on the coasts of Java and Sumatra, which agrees particularly well with observations of the 1883 events, is tentatively linked to the proximal stratigraphy of the eruption.  相似文献   

Anatomical and ultrastructural comparison of the eyes of two species of aquatic,pulmonate gastropods: The bioluminescent Latia neritoides and the non‐luminescent Ancylus fluviatilis     

V. Benno Meyer‐Rochow  Marina V. Bobkova 《新西兰海洋与淡水研究杂志》2013,47(4):739-750

Light‐adapted eyes of two freshwater gastropods with similar habitat preferences (Latia neritoides (Gray 1850) and Ancylus fluviatilis (Müller 1774)) were compared with each other in relation to optics, anatomy, and ultrastructure. Individuals of L. neritoides not only possess significantly larger eyes than similarly sized A. fluviatilis, they also have a more voluminous layer of photorecep‐tive membranes and appear capable of discerning at least some crude shapes. The eye of A. fluviatilis, on the other hand, has a very shallow retina which is so closely apposed to the lens that it can be little more than an indicator of light and darkness. Both types of eye are generously endowed with screening pigment granules and exhibit no signs of light‐induced damage. Although the lenticular F‐values for L. neritoides (1.78) and A. fluviatilis (1.74) alone are hardly indicative of an adaptation to a dark environment, the greater amount of photic vesicles and the substantial development of muscle fibres in the eye of L. neritoides suggest that the latter can adjust its vision more rapidly to changing light levels than that of A. fluviatilis. Since L. neritoides (but not A. fluviatilis) has the ability to secrete a bright green luminescent mucus, a faster accommodation system would serve the species well. There is, however, no proof that in Latia bioluminescence alone has been responsible for the development of a more capable eye. Most of the differences between the eyes of L. neritoides and A. fluviatilis can be explained by the distinctly greater nocturnal activity of L. neritoides in combination with the ability to produce bright light in the latter species.  相似文献   

Species-specific responses of late Miocene Discoaster spp. to enhanced biosilica productivity conditions in the equatorial Pacific and the Mediterranean     

Jan Backman  Isabella Raffi  Marina Ciummelli  Jack Baldauf 《Geo-Marine Letters》2013,33(4):285-298

Census data of a major Cenozoic calcareous nannofossil genus (Discoaster) have been acquired from Site U1338, located near the Equator in the eastern Pacific Ocean and drilled in 2009 during Integrated Ocean Drilling Program (IODP) Expedition 321. The investigated 147.53 m thick upper Miocene sediment sequence is primarily composed of biogenic carbonate and biogenic silica. Diatom biostratigraphic data were used to develop a revised biomagnetostratigraphic age model, resulting in more variable late Miocene sedimentation rates. Carbonate content variations mainly reflect dilution by biogenic silica production, although intense carbonate dissolution affects a few shorter intervals. Abundance variations of discoasters show no distinct correlation with either carbonate or biosilica contents. The two dominant Discoaster taxa are D. brouweri and D. variabilis, except for a 12 m thick interval where D. bellus outnumbers the sum of all other discoasters by a factor of 4.6. Data presented indicate that first D. hamatus and then D. berggrenii both evolved from D. bellus. Three unusual morphotypes, here referred to as Discoaster A, B and C, increase in relative abundance during episodes of enhanced biosilica production in the upper half of the investigated sequence (Messinian). Strikingly similar morphotypes have been observed previously in Messinian age sediments from the Mediterranean, characterized by alternating deposition of biogenic carbonate and biosilica. This suggests a species-specific response among some of the late Miocene discoasters to broader oceanographic and climatic forcing that promoted episodes of enhanced deposition of biogenic silica.  相似文献   

Fluid geochemistry of the Mondragone hydrothermal systems (southern Italy): water and gas compositions vs. geostructural setting     

Cuoco  Emilio  Minissale  Angelo  Di Leo  Antonella “Magda”  Tamburrino  Stella  Iorio  Marina  Tedesco  Dario 《International Journal of Earth Sciences》2017,106(7):2429-2444

International Journal of Earth Sciences - The geochemistry of natural thermal fluids discharging in the Mondragone Plain has been investigated. Thermal spring emergences are located along the...  相似文献   

Landscape mapping of the Russian Black Sea coast     

Petrooshina M 《Marine pollution bulletin》2003,47(1-6):187-192

The purpose of this investigation is to study structure, evolution and present ecological state of background and anthropogenically modified landscapes of the Abrau Peninsula. This region has been recommended as one of the main conservation sites on the Russian Black Sea coast due to its relatively low anthropogenic transformation and its historical importance. The ecological situation is aggravated today by the construction of a pipe-line and oil terminal near Novorossiysk and by an increase in unregulated recreation activity within the peninsula's narrow coastal zone. A special landscape-ecological map has been compiled for the model area. All ecosystems shown on the map can be grouped into four main categories based on changes of landscape structure resulting from direct impact of human activity and indirect impact mainly from chemical pollution. Ecosystems exhibiting a high degree of transformation are more typical for regions characterized by settlements, vineyards and the coastal recreation zone. Ecosystems with moderate changes also exist in the coastal area, including, for example, some unique ecosystems with pine-tree forests, pistachio-juniper and juniper open-lands. Nearly 50% of pine-tree (Pinus pithyusa) forests are in the fourth and fifth stages of recreation degradation. Some protection measures are suggested to maintain biodiversity and sustainable development of these coastal landscapes and to improve their current condition.  相似文献   

Vertical Dynamics of the Energy Release Process in a Simple two-Ribbon Flare     

VRŠSNAK  Bojan  Klein  Karl-Ludwig  Warmuth  Alexander  Otruba  Wolfgang  Skender  Marina 《Solar physics》2003,214(2):325-338

Observations of the quiescent filament eruption and the spotless two-ribbon flare of 12 September 2000 are presented. A simple flare morphology, large spatial scales, and a suitable viewing angle provide insight into characteristics of the energy release process which is attributed to the reconnection process in the current sheet formed below the eruptive filament. The flare ribbons appeared and started to expand laterally while the filament was still recognizable, enabling simultaneous measurements of the ribbon separation w and the height of the lower edge of the filament, h. The ratio w/h estimated for the expanding portions of ribbons indicates that the width-to-length ratio of the current sheet at the onset of the fast reconnection ranges between and . The ribbon elements characterized by w/h> remained stationary. The Nançay radioheliograph data in the decimeter–meter wavelengths show one group of radio bursts ahead of the filament (moving type IV burst) and another group behind the filament. The centroids of the radio sources behind the filament were confined to the region outlined by the lower edge of the filament and the magnetic inversion line, suggestive of emission from the current sheet. Sources were preferably located close to the lower edge of the filament and some appeared close to the magnetic inversion line. Two possible explanations are discussed: one in terms of the fast-mode bow shocks in the reconnection outflow jets, and another in terms of a multiple tearing of the current sheet and subsequent coalescence of plasmoids.  相似文献