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During the late Miocene, the Guadalquivir Basin and its satellite basin, the Ronda Basin, were under Atlantic cool-water influence. The aim of our study is to develop a sequence stratigraphic subdivision of the Ronda Basin fill and to provide models for the cool-water carbonates. The Upper Miocene of the Ronda Basin can be divided into three depositional sequences. Sequence 1 is early Tortonian, Sequence 2 late Tortonian to earliest Messinian, and Sequence 3 Messinian in age. The sediments were deposited in a ramp depositional system. Sequence 1 is dominated by conglomerates and marls. In Sequence 2 and Sequence 3, carbonate deposits dominate in the inner ramp whereas siliciclastics preferentially occur in the middle and outer ramp. Bryomol carbonate sediments occur in all sequences whereas rhodalgal carbonates are restricted to Sequence 3. In bays protected from siliciclastic influx, rhodalgal deposits formed under transgressive conditions. A bryomol factory occurs in zones of continuous siliciclastic supply. This distribution results from facies partitioning during the flooding of the Ronda Basin, which has a rugged and irregular relief. Embayments were protected from siliciclastic influx and provided regions with less hydraulic energy. 相似文献
2.
Christian Götze András Jung Ines Merbach Rainer Wennrich Cornelia Gläßer 《Central European Journal of Geosciences》2010,2(2):132-137
Floodplain ecosystems are affected by flood dynamics, nutrient supply as well as anthropogenic activities. Heavy metal pollution poses a serious environmental challenge. Pollution transfer from the soil to vegetation is still present at the central location of Elbe River, Germany. The goal of this study was to assess and separate the current heavy metal contamination of the floodplain ecosystem, using spectrometric field and laboratory measurements. A standardized pot experiment with floodplain vegetation in differently contaminated soils provided the basis for the measurements. The dominant plant types of the floodplains are: Urtica dioica, Phalaris arundinacea and Alopecurus pratensis, these were also chemically analysed. Various vegetation indices and methods were used to estimate the red edge position, to normalise the spectral curve of the vegetation and to investigate the potential of different methods for separating plant stress in floodplain vegetation. The main task was to compare spectral bands during phenological phases to find a method to detect heavy metal stress in plants. A multi-level algorithm for the curve parameterisation was developed. Chemo-analytical and ecophysiological parameters of plants were considered in the results and correlated with spectral data. The results of this study show the influence of heavy metals on the spectral characteristics of the focal plants. The developed method (depth CR1730) showed significant relationship between the plants and the contamination. 相似文献
3.
Luísa D.V.Carvalho Tiago Jalowitzki Ricardo Scholz Guilherme O.Gonalves Marcelo Peres Rocha Rogério Silvestre Pereir Cristiano Lana Marco Paulo de Castro Gláucia Queiroga Reinhardt A.Fuck 《地学前缘(英文版)》2022,(1):182-203
We present major and trace element compositions of mineral concentrates comprising garnet xenocrysts,ilmenite,phlogopite,spinel,zircon,and uncommon minerals (ti... 相似文献
4.
Ocean Dynamics - The existence of cross-sectionally averaged morphodynamic equilibria of tidal inlets is investigated, using a cross-sectionally averaged model, and their sensitivity to variations... 相似文献
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We present a comprehensive probabilistic hazard assessment for tephra fallout of Cotopaxi volcano (Ecuador), a quiescent but active stratovolcano known for its highly explosive behaviour. First, we developed a set of possible eruptive scenarios based on thorough field investigations, literature studies and using the Global Volcanism Program (GVP) database. Five eruption scenarios were identified, including two based on large pre-historical sub-Plinian/Plinian eruptions with eruptive parameters constrained from field investigations (One Eruption Scenario; OES) and three Eruption Range Scenarios (ERS) based on the Volcanic Explosivity Index (VEI) classification, for which eruptive parameters (i.e. erupted volume, plume height and median grainsize) were stochastically sampled within boundaries defined by VEI 3, 4 and 5. Second, the modelling was performed using the advection-diffusion model TEPHRA2 in combination with wind profiles from the NOAA NCEP/NCAR Reanalysis 1 database. We performed 1,000 runs for each eruption scenario, stochastically sampling a wind profile (OES and ERS) and a set of eruptive parameters (ERS only) at each run. Using the conditional probabilities of occurrence of eruption of VEI 3, 4 and 5 calculated from the GVP catalogue, we assessed the probability of tephra accumulation in a given time window. Based on the GVP database, a simple Poisson model shows that an eruption of VEI???3 has a 36?% probability of occurrence in the next 10?years. Finally, the hazard assessment was compiled based on three different outputs, including (i) probability maps for a given tephra accumulation, (ii) isomass maps for a given probability value and (iii) hazard curves for a given location. We conclude that the area west of Cotopaxi is exposed to light to severe tephra fallout for the smallest eruption magnitude considered (i.e. VEI 3). This area comprises a main communication axis (Panamerican Highway) topographically constrained at the bottom of the Interandean Valley, as well as the capital Quito and the town of Latacunga. In a companion paper, Biass et?al. (this volume) propose a method for a rapid risk assessment for tephra fallout using global and easily accessible data and the hazard assessment described here. 相似文献
6.
We report on biomarker responses conducted as part of a multi-level assessment of the chronic toxicity of estuarine sediments to the amphipod Gammarus locusta. A companion article accounts for organism and population-level effects. Five moderately contaminated sediments from two Portuguese estuaries, Sado and Tagus, were assessed. Three of them were muddy and two were sandy sediments. The objective was to assess sediments that were not acutely toxic. Three of the sediments met this criterion, the other two were diluted (50% and 75%) with clean sediment until acute toxicity was absent. Following 28-d exposures, the amphipods were analysed for whole-body metal bioaccumulation, metallothionein induction (MT), DNA strand breakage (SB) and lipid peroxidation (LP). Two of the muddy sediments did not cause chronic toxicity. These findings were consistent with responses at organism and population levels that showed higher growth rates and improvement of reproductive traits for amphipods exposed to these two sediments. Two other sediments, one muddy and one sandy, exhibited pronounced chronic toxicity, affecting SB, MT induction (in muddy sediment), survival and reproduction. Potential toxicants involved in these effects were identified. The last sandy sediment exhibited some loss of DNA integrity, however growth was also enhanced. Present results, together with the organism/population-level data, and also benthic communities information, were analysed under a weight-of-evidence approach. By providing evidence of exposure (or lack of it) to contaminants in sediments, the biomarkers here applied assisted in distinguishing toxicants' impacts in test organisms from the confounding influence of other geochemical features of the sediments. 相似文献
7.
The radiological environment of Svalbard 总被引：1，自引：0，他引：1
Justin P. Gwynn Mark Dowdall Corine Davids Øyvind G. Selnæs Bjørn Lind 《Polar research》2004,23(2):167-180
8.
Berta Biescas François Dufour Glória Furdada Giorgi Khazaradze Emma Suriñach 《Surveys in Geophysics》2003,24(5-6):447-464
Seismic signals generated by avalanches have been recorded by theavalanche team of the Universitat de Barcelona at theVallée de la Sionne experimental site (Switzerland) since 1998. During these years avalanches of varying size and flowwere recorded by two sensors located at different positions.In the present paper we show the general features of the running spectra of the seismicsignals for the different type of recorded avalanches. Using this method we are able not only to detect avalanches with low amplitude signals but also to distinguishbetween avalanches and other seismic sources (i.e., local earthquakes) which have thesame frequency content but a different frequency evolution. 相似文献
9.
A fast GIS-based risk assessment for tephra fallout: the example of Cotopaxi volcano, Ecuador-Part II: vulnerability and risk assessment 总被引：2，自引：0，他引：2
In order to develop efficient strategies for risk mitigation and emergency management, planners require the assessment of both the expected hazard (frequency and magnitude) and the vulnerability of exposed elements. This paper presents a GIS-based methodology to produce qualitative to semi-qualitative thematic risk assessments for tephra fallout around explosive volcanoes, designed to operate with datasets of variable precision and resolution depending on data availability. Due to the constant increase in population density around volcanoes and to the wide dispersal of tephra from volcanic plumes, a large range of threats, such as roof collapses, damage to crops, blockage of vital lifelines and health problems, concern even remote communities. To address these issues, we have assessed the vulnerability and the risk levels for five themes relevant to tephra fallout: (1) social, (2) economic, (3) environmental, (4) physical and (5) territorial. Risk and vulnerability indices for each theme are averaged to the fourth level of administrative unit (parroquia, parish). In a companion paper, Biass and Bonadonna (this volume) present a probabilistic hazard assessment for tephra fallout at Cotopaxi volcano (Ecuador) using the advection-diffusion model TEPHRA2, which is based on field investigations and a global eruption database (Global Volcanism Program, GVP). The scope of this paper is to present a new approach to risk assessment specifically designed for tephra fallout, based on a comprehensive hazard assessment of Cotopaxi volcano. Our results show that an eruption of moderate magnitude (i.e. VEI 4) would result in the possible collapse of ??9,000 houses in the two parishes located close to the volcano. Our study also reveals a high risk on agriculture, closely linked to the economic sector, and a possible accessibility problem in case of an eruption of any size, as tephra is likely to affect the only major road running from Quito to Latacunga (Panamerican Highway). As a result, this method fits into the ongoing effort to better characterize and evaluate volcanic risk, and more specifically the risk associated with tephra fallout. Although this methodology relies on some assumptions, it can serve as a rapid and efficient starting point for further investigations of the risk level around explosive volcanoes. 相似文献
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