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1.
The Almadén district is the largest mercury concentration in the world, with a total content of about 250 000 t of mercury, nearly one third of the known total mercury resources of the Earth. Mercury has been exploited since the Celtic and Roman times, with peak production during the Renaissance and between 1939–1945. The district is hosted by a Paleozoic synclinorium overlying Precambrian rocks. The Paleozoic sequence comprises epicontinental quartz arenite rocks, including black shales and quartzites. Diatremes, alkaline lavas of different composition, and late tholeiitic diabases account for the Ordovician to Devonian magmatism. The tectonic setting of this complex suite corresponds to the intraplate type. The mercury deposits of Almadén can be classified into two main types: type 1, early stratiform type ores characterized by cinnabar deposition on the lower Silurian quartzites (Criadero quartzite; e.g. the Almadén and El Entredicho deposits), and type 2, late discordant orebodies (e.g. Las Cuevas), largely hosted or related to diatremes (the `frailesca rocks') of alkaline basaltic composition. In type 1 cinnabar was deposited during diagenesis, in relation to hydrothermal circulation driven by magmatic activity. Type 2 include a variety of deposits having in common the discordant character of the orebodies (e.g. veins, stockworks, massive replacements), and their wide dispersion along the stratigraphic column, i.e. from Lower Silurian (e.g. Nueva Concepción) to Upper Devonian (e.g. Corchuelo). Received: 23 October 1998 / Accepted: 4 January 1999  相似文献   

2.
正1 Introduction Situated in the Iberian Peninsula,Lake Cisóis a sulphide-rich lake that belongs to the Ba?oles karstic system in Girona,north-eastern part of Spain.Lake Cisóis holomictic,and covers a small area of around 650 m2 and  相似文献   

3.
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4.
Contrary to the absence of a uniform Spanish identity (a phenomenon that is often referred to as Spain being a ‘nation of nations’), Spain’s confessional map is remarkably homogeneous. From the beginning of its existence as a political conglomeration, Spain has been a mono-confessional Catholic territory. Even at present, Catholicism is an intrinsic feature of Spanish society and – though officially a secular state – of state policy. A closer look at Spain’s religious situation and its corresponding pattern of church–state relations reveals, however, some recent cracks in the century’s old bond between Spain and Catholicism. Particularly secularization and religious pluralism challenge Spain’s mono-confessional Catholic nature, a development that fits well into Spain’s post-Francoist focus on Europe and European (secular) values. This paper discusses Spanish church–state relations from the beginning of its political existence until present times. Special attention will be paid to more recent societal developments and their impact on religious Spain and church–state relations.
Cathelijne de BusserEmail:
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5.
A metamorphic rock complex, strongly resembling the so-called “Granulitgebirge” of Saxony, occurs in the Spanish region Galicia. Stratigraphically, these rocks are overlain by migmatites, supracrustal metamorphites and finally by early palaeozoic strata cropping out in Western Asturias and Northern Portugal. Structurally the complex constitutes a mushroom-shaped dome which has been raised through a thin mantle of schists and gneisses along blastomylonitic borderzones containing tectonic “fish”. Petrologically it consists predominantly of rather coarsely banded, lenticular or massive rocks belonging for the greater part to the hornblende-clinozoisite granulite subfacies ofEskola's granulite facies, closely associated with eclogites, serpentinites, amphibolites and gneisses. Indications of progressive metamorphism and migmatization (especially that of a pegmatoid nature) are of strictly local occurrence, but on the other hand there is abundant evidence of one or more stages of retrograde metamorphism, particularly in the blastomylonitic horizons. The chemistry of granulites and eclogites and of their typomorphic minerals is briefly mentioned together with their metamorphic facies relations. Finally, petrogenesis and tectogenesis of the rock complex are discussed.  相似文献   

6.
The Cerro del Almirez ultramafic massif offers an example of high pressure and high temperature antigorite serpentinites. A sharp antigorite-out isograd separates them from Chl-harzburgites, consisting of olivine + enstatite + chlorite. Antigorite is characterized by aluminium contents as high as 4 wt.% Al2O3. The microstructural study shows that, prior to the transformation, antigorite is exceptionally ordered and consists of the polysome m = 17. No polysomatic defect occurs in antigorite forming most of the Cerro del Almirez serpentinites. Close to the antigorite-out isograd, limited disorder features may occur, mainly as (001) twins, reaction rims and reduction of m down to 14–15. Here, local recrystallization phenomena lead to sporadic growth of large antigorite and chlorite crystals.  相似文献   

7.
Summary Tourmalinites containing quartz, Li- and Cs-micas, and small amounts of arsenopyrite occur near Cáceres, Spain. The tourmalinites are developed within Ordovician pelites near the eastern margin of the Cabeza de Araya batholith and close to several small bodies of tectonized granite. Field and textural relationships document an epigenetic character for the tourmalinites. The tourmaline is fine to very fine-grained and its composition is intermediate within the schorl-dravite solid-solution series. Hydrothermal veins containing quartz, muscovite, amblygonite-montebrasite, apatite, fluorite, and/or cassiterite appear spatially related to the tourmalinites. The mineralized area is located in a shear zone that was active during D3 Hercynian deformation and the emplacement of granitic bodies. Tourmalinites and veins derived from B- and Li-rich magmatic-hydrothermal fluids are believed to have been associated with the intrusion of a hidden granite dome, the tourmalinites being produced by extensive metasomatism of Ordovician metasedimentary rocks.
Turmalinite and Sn-Li-Vererzungen im Valdeflores Gebiet (Cáceres, Spanien)
Zusammenfassung Turmalinite, die Quarz, Li- und Cs-Glimmer, sowie geringe Mengen an Arsenkies führen, kommen in der Ne von Cáceres, Spanien, vor. Sie sind an ordovizische Metapelite in der Nähe des Cabeza de Araya Batholiths und kleinere tektonisierte Granitkörper gebunden. Eine epigenetische Genese der Turmalinite ist auf Grund von Feldbeziehungen und texturellen Beobachtungen belegt. Die Zusammensetzung der sehr feinkörnigen Turmaline entspricht intermediären Gliedern der Schörl-Dravit- Reihe. Hydrothermale Gänge mit Quarz, Muskowit, Amblygonit-Montebrasit, Apatit, Fluorit und/oder Zinnstein treten benachbart zu den Turmaliniten auf. Der mineralisierte Bereich ist an eine Scherzone gebunden, die während der hercynischen D3 Deformation und der Platznahme der Granite aktiv war. Turmalinite und Gänge lassen sich genetisch von magmatisch-hydrothermalen Fluiden ableiten, die mit der Intrusion eines nicht aufgeschlossenen Granitdomes zusammenhängen. Die Turmalinite sind das Produkt einer weiträumigen Metasomatose der ordovizischen Metasedimente.

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8.
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9.
Water resources management in coastal wetlands requires the degree of interdependence between groundwater and terrestrial ecosystems to be known. This is especially so in semiarid areas where surface inflows are restricted, marine influence is marked and the evaporation rate is high. Thus, chemistry of surface waters is very variable in the Cerrillos-Punta Entinas wetlands system. Using classical hydrogeochemical tools, the main processes that favor a diversity of water types were described, related to: presence of salt deposits on the lagoon beds, marine origin of the water, and local influence of groundwater. All these factors make it difficult to establish what reference conditions should be used to define “good” water quality of the surface waters—as required by the Water framework directive—and to understand the influence of groundwater on these coastal wetlands. Knowledge about the influence of the different interaction of these factors on the hydrogeochemical dynamics is required for the sustainable management of this protected natural site.  相似文献   

10.
This paper presents a new Holocene palaeoecological record from coastal south-eastern Spain, a region characterised by high plant species diversity, varied physiography, high risk of desertification, and a history of human pressure on the landscape that stretches to antiquity. The pollen sequence shows four main vegetation phases: the first characterised by mixed forests of Pinus and evergreen Quercus accompanied by broad-leaved mesophilous trees, and a diversity of Mediterranean scrub; the second phase is characterised by mesophytic decline and expansion of Artemisia; a third, mid-Holocene phase of thermo-mesophytic maxima with prevalence of forested landscapes; and, finally, the progressive opening of the landscape with sparse pines, halo-xerophytic grasslands and sclerophyllous brushwood. The current treeless situation of south-eastern Spain is a relatively recent feature resulting from a dramatic change in the ecological structure of the regional landscapes. This paper stresses the continued vulnerability of these arid systems in the face of a changing climate. This sequence adds to previous palaeobotanical records (pollen and charcoal) and archaeological reports to suggest that deforestation started earlier in low-elevation areas and river basins than in the inland mountains and platforms, a factor that appears in connection to human exploitation of the natural environment.  相似文献   

11.
Tsunamis can represent a significant risk to the population and cause huge economic damage in many costal regions. In order to be able to identify risk hot spots and implement targeted risk reduction measures, decision makers need to have a clear picture of the risk situation in their countries or regions. This work reviews existing approaches for tsunami risk assessment and recommends a five-step process for assessing tsunami risk. As a case study, a qualitative risk assessment for a worst-case tsunami scenario was carried out to understand the tsunami risk to the population in Cádiz. Moreover, a sensitivity analysis of the tsunami hazard input parameters was performed as a strong influence of the variability of the input parameters on the resultant tsunami hazard and risk zonation maps was observed. The study shows that regardless of the assumptions made a non-negligible tsunami risk to Cádiz exists.  相似文献   

12.
Evaluating aquifer–river interactions is naturally complex, particularly within urban settings. This is largely due to the difficulties involved in quantifying most elements of the water balance. The ability of numerical models to deal with several dynamic variables simultaneously makes them valuable tools to address this kind of problem. An applied, modeling-based approach to investigate the spatial and temporal variations of aquifer–river connectivity within a shallow urban aquifer is presented. Model development is based on comprehensive field campaigns in Langreo, Spain. Two calibration runs (for summer and winter conditions) were carried out in order to evaluate the spatial distribution of recharge rates. The model suggests that baseflows are largely negligible in comparison with total streamflows. This is mostly attributed to the abrupt nature of the catchment, which prevents the existence of sufficiently large alluvial systems to a great extent. Modelling results also show that aquifer–river connectivity at the study site is constrained by urban pumping as well as by seasonal fluctuations.  相似文献   

13.
The Munébrega Plio-Quaternary half-graben is a NW-SE trending neotectonic depression located in the central sector of the intraplate Iberian Range (NE Spain). The master fault of the half-graben offsets an Upper Pleistocene pediment deposit, forming an upslope-facing scarp. A trench dug across the fault scarp exposed a 25-m wide deformation zone consisting of graben and horst fault blocks with fissures in the upper part of the scarp, and a monoclinal flexure affected by normal and reverse faults in the lower part of the scarp. We infer a minimum of three faulting events over the past 72 ka, yielding an average (maximum) recurrence interval of 24 ka. The oldest event (72–41 ka) produced an antislope scarp on the relict pediment surface, confining deposition to the downthrown block. Cross-cutting faults affecting sedimentary units deposited in the sediment trap produced by the first event provide evidence for at least two younger events (33–19? ka). The measured cumulative vertical displacement (7.4 m) yield a minimum vertical slip rate of 0.10 ± 0.01 mm/year (2σ error) for the past 72 ka. If the paleoearthquakes ruptured the whole mappable length of the fault (ca. 20 km), they probably had moment magnitudes ca. 6.9 (Stirling et al. Bull Seismol Soc Am, 2002). Such earthquakes would have been more than a magnitude unit larger than the largest ones recorded historically in the Iberian Range. These results suggest that the official seismic hazard assessments, based solely on the historic and instrumental record, may underestimate the seismic hazard in the area.  相似文献   

14.
The karstic Lake Montcortès sedimentary sequence spanning the last 1548 yr constitutes the first continuous, high-resolution, multi-proxy varved record in northern Spain. Sediments consist of biogenic varves composed of calcite, organic matter and detrital laminae and turbidite layers. Calcite layer thickness and internal sub-layering indicate changes in water temperature and seasonality whereas the frequency of detrital layers reflects rainfall variability. Higher temperatures occurred in Lake Montcortès in AD 555–738, 825–875, 1010–1322 and 1874–present. Lower temperatures and prolonged winter conditions were recorded in AD 1446–1598, 1663–1711 and 1759–1819. Extreme and multiple precipitation events dominated in AD 571–593, 848–922, 987–1086, 1168–1196, 1217–1249, 1444–1457, 1728–1741 and 1840–1875, indicating complex hydrological variability in NE Spain since AD 463. The sedimentary record of Lake Montcortès reveals a short-term relation between rainfall variability and the detrital influx, pronounced during extended periods of reduced anthropogenic influences. In pre-industrial times, during warm climate episodes, population and land use increased in the area. After the onset of the industrialization, the relationship between climate and human activities decoupled and population dynamics and landscape modifications were therefore mostly determined by socio‐economic factors.  相似文献   

15.
The Jálama pluton (JP) is a Variscan peraluminous granitoid that intruded into low-grade metasediments from the Central Iberian Zone (CIZ). It comprises a sillimanite-bearing two-mica monzogranite in the inner zone, followed by a tourmaline-bearing two-mica monzogranite, and a marginal tourmaline-muscovite leucogranite in the northern half of the pluton. Microgranitoid enclaves and metasedimentary xenoliths occur locally in monzogranites. The change in rock type from the central monzogranite to the marginal leucogranite corresponds to decreasing TiO2, MgO, FeO, CaO, Sr, Ba, Zr, and ΣREE, and increasing SiO2, Na2O, P2O5, Rb, Li, Cs, Ta, Sn, and W. Fe/(Fe+Mg) ratios in biotite, muscovite and tourmaline increase with increasing Fe/(Fe+Mg) in bulk rock, suggesting an important control of the bulk-rock composition on mineral chemistry. The high peraluminosity, the low CaO and high P contents, as well as the similarity of ε(Nd)300 values in both the granites and metasediments of the southern CIZ constitute strong evidences for a crustal origin of the granite suite, probably by melting of these metasedimentary rocks. Field and petrographic observations, together with mineralogical and geochemical data, suggest that assimilation and mingling/mixing acted in concert with fractional crystallization during the formation of the JP. These processes may also have been important in the evolution of other granitoids from this region.  相似文献   

16.
The morphotectonics of Córdoba and Granada are differentiated using the Rantsman method [53]. Over 40 quantitative geomorphologic indicators are used in the systemic classification. Both areas are included in what are known as the macroblocks no. 1 (Southern) and no. 2 (Sub-Western 2A) of the Iberian Peninsula megablock. The qua ntities of the four lowest order Territorial Units defined for Córdoba/Granada are: mesoblocks (4/4), blocks (9/9), microblocks (15/35) and nanoblocks (64/83). The main lineaments/intersections determined in Córdoba total 16/1041 and in Granada 25/633, A series of seven morphostructural scarps is found in both areas, along with important modifications (inflections) in some river beds. Some of the structures described are seismicity-related. Córdoba displays less activity than Granada. Between the towns of Loja, Beas de Granada, and Lentejí a seismoactive sector (～820 km2) with blocks B2, B3, B5, and B6 forms the area where the deep earthquakes are concentrated.  相似文献   

17.
A Permo-Triassic pelite-carbonate rock series (with interacalated metabasitic rocks) in the Cordilleras Béticas, Spain, was metamorphosed during the Alpine metamorphism at high pressures (P min near 18 kbar). The rocks show well preserved sedimentary features of evaporites such as pseudomorphs of talc, of kyanite-phengitetalc-biotite, and of quartz after sulfate minerals, and relicts of baryte, anhydrite, NaCl, and KCl, indicating a salt-clay mixture of illite, chlorite, talc, and halite as the original rock. The evaporitic metapelites have a whole rock composition characterized by high Mg/(Mg+Ca) ratios>0.7, variable alkaline and Sr, Ba, contents, but are mostly K2O rich (<8.8 wt%). The F (<2600 ppm), Cl (<3600 ppm), and P2O5 (<0.24 wt%) contents are also high. The pelitic member of this series is a fine grained biotite rock. Kyanite-phengite-talc-biotite aggregates in pseudomorphs developed in the high pressure stage. Albite-rich plagioclase was formed when the rocks crossed the albite stability curve in the early stages of the uplift. Scapolite, rich in NaCl (Ca/(Ca+Na) mol% 24–40) and poor in SO4, with Cl/(Cl+CO3) ratios between 0.6 and 0.8, formed as porphyroblasts, sometimes replacing up to 60% of the rock in a late stage of metamorphism (between 10 and 5 kbar, near 600°C). No reaction with albite is observed, and the scapolite formed from biotite by: $$\begin{gathered} Al - biotite + CaCO_3 + NaCl + SiO_2 \hfill \\ = Al - poor biotite + scapolite + MgCO_3 + KCl \hfill \\ + MgCl_2 + H_2 O \hfill \\ \end{gathered}$$ Calculated fluid composition in equilibrium with scapolite indicates varying salt concentrations in the fluid. Distribution of Cl and F in biotite and apatite also indicates varying fluid compositions.  相似文献   

18.
Summary The Mérida wollastonite deposits (SW Spain) occur in the inner part of a contact-metamorphic aureole developed on impure carbonate rocks of Lower Cambrian age, by the intrusion of a late Hercynian granite. Contact metamorphism associated with the granite emplacement did not only cause an important thermic anomaly but also triggered a complex fluid-rock interaction driven by infiltration of externally-derived fluids. Petrographic and stable isotope data suggest that the aureole was infiltrated by large amounts of aqueous fluids, emanating from the nearby granite, through lithological contacts. As a result of fluid infiltration, an extensive dilution of the CO2-rich fluid phase evolved by prograde devolatilization reactions took place, thus providing an environment suitable for wollastonite formation.Nearly pure wollastonite bands resulted from chert interlayered in limestone by local exchange between CaO and SiO2 across bimetasomatic rims, in the presence of virtually pure water showing a magmatic-dominated isotope signature (18O values as low as 11.8 are recorded for wollastonites adjacent to the granite contact). Distribution and modal abundance of wollastonite provide insights for determining the fluid flow paths and the extent of infiltration. Fluid circulation was dominantly parallel to bedding and clearly focused along marble-metachert boundaries, whi-ch acted as channelways for migration of fluids in the direction of decreasing temperature. Conditions of wollastonite formation have been estimated as follows: P=570-700 bars; T = 550-600°C; and XCO 2 0.05.
Der Effekt von Fluidinfiltration auf die Genese von Wollastonit in den kontaktmetamorphen Lagerstätten von Mérida, SW Spanien
Zusammenfassung Die Woliastonitlagerstätten von Mérida (SW Spanien) treten im Innenteil einer kontaktmetamorphen Aureole, die sich durch die Intrusion späthercynischer Granite in unreine unterkambrische Karbonatgesteine bildete, auf. Die die Granitplatznahme begleitende Kontaktmetamorphose verursachte nicht nur eine bedeutende thermische Anomalie, sondern löste, kontrolliert durch die Infiltration externer Fluide, auch komplexe Fluid-Gesteinsinteraktion aus. Peterographische und stabile Isotopendaten weisen darauf hin, daß in die Aureole große Mengen an wäßrigen Lösungen, die aus dem nahegelegenen Granit abzuleiten sind, vor allem entlang lithologischer Grenzen infiltrierten. Als Folge der Fluidinfiltration kam es zu einer starken Verdünnung des durch prograde Devolatilisationsreaktionen entstandenen CO2-reichen Fluids und zur Bildung von Wollastonit.Nahezu reine Wollastonitbänder entstanden aus den dem Kalk zwischengelagertem Chert durch lokalen CaO- und SiO2-Austausch über bimetasomatische Ränder und zwar in Gegenwart eines offenbar reinen wäßrigen Fluids mit rnagmatisch-dominierter Isotopensignatur (18O Werte bis 11.8 sind für Wollastonite nahe des Granitkontaktes nachgewiesen). Die Verteilung und die Modalgehalte von Wollastonit erlauben Einblicke in die Bestimmung der Fluidpfade und das Ausmaß der Infiltration. Die Fluidzirkulation erfolgte hauptsächlich parallel zur Schichtung und ist auf die Marmor-Metachert-Grenzen fokussiert, die als Zufuhrkanäle für die Migration der Fluide in Richtung fallender Temperatur agierten. Die Bedingungen der Wollastonitbildung werden folgendermaßen abgeschätzt: P = 570-700 bar; T=550-600°C; XCO 2 20.05.
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19.
The challenge of sustainability is not about producing more or better managerial knowledge. It is in fact a transformation of the systems and structures that perpetuate environmental problems that is emerging as the key sustainability goal. In this paper we show the relevance of this argument, by using wildfires as symptoms of the challenges posed by global change to western societies, where wildfires are becoming increasingly problematic. Climate change, land abandonment, exurban expansion and fire suppression schemes are some of the main reasons behind this. Tackling the increasing intensity and complexity of wildfires is consequently emerging as an important research and policy topic. A central question in the literature is how to achieve a more sustainable coexistence with wildfire. Fuel reduction treatments, fire restoration, the reform of current suppression policies and adaptive institutional arrangements have all been debated. However, the social-ecological transformations needed to effectively implement these management options are not sufficiently understood. This paper looks at the efforts of the Catalan wildfire management system to cope with wildfire risk over the last decades. In particular, the emergence of GRAF, a group of wildfire fighting specialists in the Fire Department, is described. Emphasizing the need to understand wildfires as an inherent part of Mediterranean ecosystems, the expansion of GRAF highlights how learning to coexist with wildfire in Catalonia has triggered a set of transformative processes in institutional arrangements and power relationships of the wildfire management system. Our data also illustrate how coexisting with wildfire entails a dramatic social-ecological transformation in terms of land-uses, settlement patterns, energy supply systems and social values about wildfires. Moreover, we warn that in the absence of such systemic changes, management improvements might paradoxically reinforce risk. We conclude that wildfire researchers and practitioners should link the proposed management options to a deeper debate on how to produce alternative, less flammable landscapes, as agents of a broader social-ecological transformation to sustainability.  相似文献   

20.
The variations of groundwater quality in the unconfined zone of the Almonte-Marismas aquifer, upon which Doñana National Park is located, are analysed. Most sampled points are multiple piezometers, allowing for the vertical distribution study of the hydrogeochemical characteristics in the aquifer. Temperature, pH, electrical conductivity, dissolved oxygen and redox potential were determined in the field. A large number of parameters, including major ions and a large amount of minor and trace elements, were analysed. In the southern zone, where aeolian sands crop out, water composition in the shallower part of the aquifer is of the sodium chloride type, with low pH (5.5–6) and mineralization (<200 μS/cm) values. As water circulates through the aquifer, bicarbonate and calcium concentrations increase slightly. In agricultural or urban zones, nitrates and sulphates present their highest contents in the upper part of the aquifer. In zones with low pH levels (around 6), concentration of many trace metals (Al, Co, Cr, Cu, Ni, Zn, etc.) also shows a distribution similar to that of sulphates and nitrates, which indicates its fertilizer-linked origin. In zones with neutral or alkaline pH, regardless of high nitrate content, concentration of the above mentioned metals is very low due to its immobilisation by surface adsorption processes. The distribution of Br contents also shows the effects of agricultural pollution.  相似文献   

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