Multiple generation magmatic and hydrothermal processes in a Martian subvolcanic environment based on the analysis of Yamato-000593 nakhlite meteorite     

Ildiko Gyollai  Elias Chatzitheodoridis  Ákos Kereszturi  Máté Szabó 《Meteoritics & planetary science》2023,58(2):218-240

We studied the occurrence of secondary minerals and inferred their formation in the Yamato-000593 Martian meteorite using multiple technological approaches such as electron probe micro analysis, optical microscope, Raman spectroscopy, scanning electron microscopy, as well as Fourier transform-infrared microscopy and spectroscopy. Two separate hydrothermal alteration events and their sequence of formation (based on superpositional relationship) can be identified: an elevated temperature phase producing high-temperature sulfidic hydrothermal alteration and a lower temperature hydrothermal alteration phase by iron-rich fluids. This meteorite shows signatures more compatible with magmatic effects, rather than impact-induced hydrothermal alteration, as has been proposed earlier. The sulfidic alteration probably formed by magmatic hydrothermal fluids, whereas iron-rich hydrothermal fluid circulation after a possible early impact event has also been proposed, when the fluids cooled down to 50 °C. Most of the secondary minerals formed at alkaline-neutral conditions, and the few observed signatures (clay–silica-bearing veins, siderite-iron-oxide veins) of briny conditions are probably from local spatial effects in larger cavities. The ferrous minerals (hematite and siderite) along the fractures could be crystallized from Fe-HCO₃-bearing fluids. Alternatively, the primary magmatic minerals could have been oxidized easily (Fe-rich olivines, magnetite) during the cooling to iron oxides (hematite, goethite). The results suggest the possible existence of at least ephemerally habitable environments on Mars, mainly at volcanically heated locations. Following published geochemical models, the carbonates formed within acidic-circumneutral condition, which was followed by formation of phyllosilicates in alkaline condition.  相似文献   

Mushroom production as an alternative for rural development in a forested mountainous area     

José A. BONET  José R. GONZáLEZ-OLABARRIA  Juan MARTíNEZ DE ARAGóN 《山地科学学报》2014,11(2):535-543

Wild mushrooms are recognized as important non-wood forest products in mountainous ecosystems, but their real potential for generating rural economies has not been fully evaluated due to the difficulties in obtaining reliable productivity data, minimizing their true potential as contributor to rural economies. Mushroom yield models based on large data series from Pinus forest ecosystems in the region of Catalonia(Spain), combined with data from the Spanish National Forest Inventory allow us to estimate the potential mushroom productivity by forest ecosystems. The results of 24,500 tons/yr of mushrooms of which 16,300 tons are classified as edible and 7,900 tons are commonly marketed demonstrate the importance of mushroom productions in Catalonian pine forests, mostly located in mountainous areas where the development of agricultural activities is limited. Economic mushroom value is estimated at 48 million € for the edible mushroom and 32 million € for those corresponding to marketable yields, confirming the potential of this non-wood forest product. These production results and corresponding economic values provide a basis for the incorporation of wild mushrooms as significant non-wood forest products in the development of forest policies in mountainous areas.  相似文献   

Interannual variability in the biochemical composition of newly hatched larvae of the spider crab Maja brachydactyla (Decapoda,Majidae)     

Guiomar Rotllant  Carles G. Simeó  Guillermo Guerao  Marta Sastre  Daniel F. R. Cleary  Ricardo Calado  Alicia Estévez 《Marine Ecology》2014,35(3):298-307

The spider crab Maja brachydactyla is an important commercial species in Europe and supports intensive fisheries in the NE Atlantic. A field survey was performed to assess long‐term and consecutive interannual (2005–2010) variation of the biochemical composition of newly hatched larvae of M. brachydactyla. Larval biochemical profiles differed significantly among years, with pronounced differences being recorded in 2010. Differences among batches of newly hatched larvae were mainly explained by the contribution of triacylglycerols and, to a lesser degree, by protein and lipid content. The use of different nutrition indices is discussed. The biochemical composition of newly hatched larvae from M. brachydactyla was highly variable, even though surveyed broodstock was obtained from the same local population and was always sampled during the same season. The unpredictable biochemical profiles of newly hatched larvae may condition their survival and recruitment. This largely overlooked aspect of larval variability should be considered in future fisheries management strategies and captive production of marine organisms that still rely on wild seeds.  相似文献   

Pockmarks on either side of the Strait of Gibraltar: formation from overpressured shallow contourite gas reservoirs and internal wave action during the last glacial sea-level lowstand?     

Ricardo León  Luis Somoza  Teresa Medialdea  Francisco Javier González  Carmen Julia Gimenez-Moreno  Raúl Pérez-López 《Geo-Marine Letters》2014,34(2-3):131-151

Integrating novel and published swath bathymetry (3,980 km²), as well as chirp and high-resolution 2D seismic reflection profiles (2,190 km), this study presents the mapping of 436 pockmarks at water depths varying widely between 370 and 1,020 m on either side of the Strait of Gibraltar. On the Atlantic side in the south-eastern Gulf of Cádiz near the Camarinal Sill, 198 newly discovered pockmarks occur in three well localized and separated fields: on the upper slope (n=14), in the main channel of the Mediterranean outflow water (MOW, n=160), and on the huge contourite levee of the MOW main channel (n=24) near the well-known TASYO field. These pockmarks vary in diameter from 60 to 919 m, and are sub-circular to irregularly elongated or lobate in shape. Their slope angles on average range from 3° to 25°. On the Mediterranean side of the strait on the Ceuta Drift of the western Alborán Basin, where pockmarks were already known to occur, 238 pockmarks were identified and grouped into three interconnected fields, i.e. a northern (n=34), a central (n=61) and a southern field (n=143). In the latter two fields the pockmarks are mainly sub-circular, ranging from 130 to 400 m in diameter with slope angles averaging 1.5° to 15°. In the northern sector, by contrast, they are elongated up to 1,430 m, probably reflecting MOW activity. Based on seismo-stratigraphic interpretation, it is inferred that most pockmarks formed during and shortly after the last glacial sea-level lowstand, as they are related to the final erosional discontinuity sealed by Holocene transgressive deposits. Combining these findings with other existing knowledge, it is proposed that pockmark formation on either side of the Strait of Gibraltar resulted from gas and/or sediment pore-water venting from overpressured shallow gas reservoirs entrapped in coarse-grained contourites of levee deposits and Pleistocene palaeochannel infillings. Venting was either triggered or promoted by hydraulic pumping associated with topographically forced internal waves. This mechanism is analogous to the long-known effect of tidal pumping on the dynamics of unit pockmarks observed along the Norwegian continental margin.  相似文献   

IAG Newsletter     

Gyula Tóth 《Journal of Geodesy》2014,88(2):199-205

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IAG Newsletter     

Gyula Tóth 《Journal of Geodesy》2014,88(5):515-516

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IAG Newsletter     

Gyula Tóth 《Journal of Geodesy》2014,88(1):87-92

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Assessment of RegCM4 simulated inter-annual variability and daily-scale statistics of temperature and precipitation over Mexico     

Ramón Fuentes-Franco  Erika Coppola  Filippo Giorgi  Federico Graef  Edgar G. Pavia 《Climate Dynamics》2014,42(3-4):629-647

The skill of a regional climate model (RegCM4) in capturing the mean patterns, interannual variability and extreme statistics of daily-scale temperature and precipitation events over Mexico is assessed through a comparison of observations and a 27-year long simulation driven by reanalyses of observations covering the Central America CORDEX domain. The analysis also includes the simulation of tropical cyclones. It is found that RegCM4 reproduces adequately the mean spatial patterns of seasonal precipitation and temperature, along with the associated interannual variability characteristics. The main model bias is an overestimation of precipitation in mountainous regions. The 5 and 95 percentiles of daily temperature, as well as the maximum dry spell length are realistically simulated. The simulated distribution of precipitation events as well as the 95 percentile of precipitation shows a wet bias in topographically complex regions. Based on a simple detection method, the model produces realistic tropical cyclone distributions even at its relatively coarse resolution (dx = 50 km), although the number of cyclone days is underestimated over the Pacific and somewhat overestimated over the Atlantic and Caribbean basins. Overall, it is assessed that the performance of RegCM4 over Mexico is of sufficient quality to study not only mean precipitation and temperature patterns, but also higher order climate statistics.  相似文献   

The Water Framework Directive: Can more information be extracted from groundwater data? A case study of Seewinkel,Burgenland, eastern Austria     

István Gábor Hatvani  Norbert Magyar  Matthias Zessner  József Kovács  Alfred Paul Blaschke 《Hydrogeology Journal》2014,22(4):779-794

Water protection is one of the most important goals in environmental protection. The Clean Water Act in the USA and the Water Framework Directive (WFD) in Europe are the legal frameworks to facilitate the achievement of this goal. The question is raised of whether more information can be extracted from WFD-related groundwater data. To answer it, a methodology has been developed that is easy to use and could be implemented into official practice. A case study is presented in which the groundwater data of a sodic area in Austria (Seewinkel) is assessed. Eighteen parameters in groundwater sampled from 23 wells (1991–2011) were analyzed. With basic statistics, trend-, cluster-, Wilks’ λ and spatial sampling density analysis, local phosphorus and boron phenomena were described, along with the determining role of sulphate, groundwater flow, and the oxygen gradient in the area. As a final step, the spatial sampling density was determined. Regarding the current set of parameters, all the sampling sites are necessary and only in the case of certain parameters (Ca²⁺, Mg²⁺, K⁺, NO₃ ^?, pH) could one sampling site be abandoned. The methodology applied brings a new perspective to exploring groundwater data collected according to the requirements of the WFD.  相似文献   

Geophysical exploration on the subsurface geology of La Garrotxa monogenetic volcanic field (NE Iberian Peninsula)     

Xavier Bolós  Stéphanie Barde-Cabusson  Dario Pedrazzi  Joan Martí  Albert Casas  Raúl Lovera  Daniel Nadal-Sala 《International Journal of Earth Sciences》2014,103(8):2255-2269

We applied self-potential (SP) and electrical resistivity tomography (ERT) to the exploration of the uppermost part of the substrate geology and shallow structure of La Garrotxa monogenetic volcanic field, part of the European Neogene–Quaternary volcanic province. The aim of the study was to improve knowledge of the shallowest part of the feeding system of these monogenetic volcanoes and of its relationship with the subsurface geology. This study complements previous geophysical studies carried out at a less detailed scale and aimed at identifying deeper structures, and together will constitute the basis to establish volcanic susceptibility in La Garrotxa. SP study complemented previous smaller-scale studies and targeted key areas where ERT could be conducted. The main new results include the generation of resistivity models identifying dykes and faults associated with several monogenetic cones. The combined results confirm that shallow tectonics controlling the distribution of the foci of eruptive activity in this volcanic zone mainly correspond to NNW–SSE and accessorily by NNE–SSW Neogene extensional fissures and faults and concretely show the associated magmatic intrusions. These structures coincide with the deeper ones identified in previous studies, and show that previous Alpine tectonic structures played no apparent role in controlling the loci of this volcanism. Moreover, the results obtained show that the changes in eruption dynamics occurring at different vents located at relatively short distances in this volcanic area are controlled by shallow stratigraphical, structural and hydrogeological differences underneath these monogenetic volcanoes.  相似文献