Application of the FAO quantitative and SINDI methods to assess the quality of different soils in Castilla-La Mancha (Spain)

In the region of Castilla-La Mancha (Spain), over half of the soils are under cropping. This vast agricultural activity, combined with other anthropological uses, has led to a deterioration of the soil quality and virtual degradation. Therefore, it was deemed to assess the quality of these soils, which was achieved by applying two different methods. Three soils, representative of typical conditions in this community, were sampled and diverse properties were analysed in order to apply two different approaches. The first soil evaluation was carried out by a traditional method developed by FAO using a productivity index, whereas the second method consisted of the application of a new method called SINDI, developed in New Zealand. Both approaches make an evaluation based on a number of indicators that differs in each case. These differences explain why each method ranked the soils studied in different order reaching diverse conclusions on their quality.     

Geology and rural landscapes in central Spain (Guadalajara, Castilla—La Mancha)

Methods commonly used in regional geological analysis were employed to study the visual landscapes of the Sigüenza–Molina de Aragón area (Spain). Landscape data were compiled to produce a landscape map and a photograph catalogue. Lithological composition, tectonic structure and recent erosive processes are the main factors controlling the visual landscapes. Territorial properties, such as colours and agricultural capacities, are controlled by these geological characteristics. The landscape map and the photographic catalogue is the main contribution of this paper. The first level of landscape classification distinguishes zones with dominance of either flat, concave or convex areas. Other parts of the territory are, however, composed of concave and convex combinations that originate hybrid orographic structures. In a second level of classification, several subdivisions for each of these types are established.     

Pedo-geochemical baseline content levels and soil quality reference values of trace elements in soils from the Mediterranean (Castilla La Mancha, Spain)

To evaluate trace element soil contamination, geochemical baseline contents and reference values need to be established. Pedo-geochemical baseline levels of trace elements in 72 soil samples of 24 soil profiles from the Mediterranean, Castilla La Mancha, are assessed and soil quality reference values are calculated. Reference value contents (in mg kg^?1) were: Sc 50.8; V 123.2; Cr 113.4; Co 20.8; Ni 42.6; Cu 27.0; Zn 86.5; Ga 26.7; Ge 1.3; As 16.7; Se 1.4; Br 20.1; Rb 234.7; Sr 1868.4; Y 38.3; Zr 413.1; Nb 18.7; Mo 2.0; Ag 7.8; Cd 4.4; Sn 8.7; Sb 5.7; I 25.4; Cs 14.2; Ba 1049.3; La 348.4; Ce 97.9; Nd 40.1; Sm 10.7; Yb 4.2; Hf 10.0; Ta 4.0; W 5.5; Tl 2.3; Pb 44.2; Bi 2.2; Th 21.6; U 10.3. The contents obtained for some elements are below or close to the detection limit: Co, Ge, Se, Mo, Ag, Cd, Sb, Yb, Hf, Ta, W, Tl and Bi. The element content ranges (the maximum value minus the minimum value) are: Sc 55.0, V 196.0, Cr 346.0, Co 64.4, Ni 188.7, Cu 49.5, Zn 102.3, Ga 28.7, Ge 1.5, As 26.4, Se 0.9, Br 33.0 Rb 432.7, Sr 3372.6, Y 39.8, Zr 523.2, Nb 59.7, Mo 3.9, Ag 10.1, Cd 1.8, Sn 75.2, Sb 9.9, I 68.0, Cs 17.6, Ba 1394.9, La 51.3, Ce 93.5, Nd 52.5, Sm 11.2, Yb 4.2, Hf 11.3, Ta 6.3, W 5.2, Tl 2.1, Pb 96.4, Bi 3.0, Th 24.4, U 16.4 (in mg kg^?1). The spatial distribution of the elements was affected mainly by the nature of the bedrock and by pedological processes. The upper limit of expected background variation for each trace element in the soil is documented, as is its range as a criterion for evaluating which sites may require decontamination.     

Sulphide-mining impacts in the physical environment: Sierra de Cartagena–La Unión (SE Spain) case study

The environmental impact and potential-risk assessment of an abandoned sulphide-mining site in a semiarid climate is presented here, by the study case of Sierra de Cartagena–La Unión (SE Spain), a 2,500-year-old mining district extending over an area of 100 km². The regional map illustrates the existence of 12 open-pits, 1,902 mining wells, 2,351 waste deposits, including 89 tailing dams and waste rock derived from mining processes. Mine wastes occupy an area of 9 km² and have an approximate volume of 200 Mm³. Mineralogical, physical and chemical data distinguish nine different types of mine and metallurgical waste. According to the concentration of sulphate and heavy metals in sediment, soil, rainwater, surface water and groundwater samples, it is possible to conclude that the impact of mine activities occurs not only in the immediate mining area (100 km²), but also in the surrounding areas (an affected area of 1,000 km² approximately). The hydrochemical data show that groundwater, runoff water and some rainwater samples exceed Spanish and European water quality guideline values for water supply. The main geochemical process recognised is sulphide-mineral oxidation and later-generated sulphate dissolution by groundwater and runoff. Runoff and wind are the major mechanisms of metals and sulphate transport in the study area and adjacent zones.     

Larger foraminifera distribution and strontium isotope stratigraphy of the La Cova limestones (Coniacian–Santonian, “Serra del Montsec”, Pyrenees, NE Spain)

The Upper Cretaceous La Cova limestones (southern Pyrenees, Spain) host a rich and diverse larger foraminiferal fauna, which represents the first diversification of K-strategists after the mass extinction at the Cenomanian–Turonian boundary.The stratigraphic distribution of the main taxa of larger foraminifera defines two assemblages. The first assemblage is characterised by the first appearance of lacazinids (Pseudolacazina loeblichi) and meandropsinids (Eofallotia simplex), by the large agglutinated Montsechiana montsechiensis, and by several species of complex rotalids (Rotorbinella campaniola, Iberorotalia reicheli, Orbitokhatina wondersmitti and Calcarinella schaubi). The second assemblage is defined by the appearance of Lacazina pyrenaica, Palandrosina taxyae and Martiguesia cyclamminiformis.A late Coniacian-early Santonian age was so far accepted for the La Cova limestones, based on indirect correlation with deep-water facies bearing planktic foraminifers of the Dicarinella concavata zone. Strontium isotope stratigraphy, based on many samples of pristine biotic calcite of rudists and ostreids, indicates that the La Cova limestones span from the early Coniacian to the early-middle Santonian boundary. The first assemblage of larger foraminifera appears very close to the early-middle Coniacian boundary and reaches its full diversity by the middle Coniacian. The originations defining the second assemblage are dated as earliest Santonian: they represent important bioevents to define the Coniacian-Santonian boundary in the shallow-water facies of the South Pyrenean province.By means of the calibration of strontium isotope stratigraphy to the Geological Time Scale, the larger foraminiferal assemblages of the La Cova limestones can be correlated to the standard biozonal scheme of ammonites, planktonic foraminifers and calcareous nannoplankton. This correlation is a first step toward a larger foraminifera standard biozonation for Upper Cretaceous carbonate platform facies.     

Origin of quartz geodes from Laño and Tubilla del Agua sections (middle–upper Campanian,Basque‐Cantabrian Basin,northern Spain): isotopic differences during diagenetic processes

Quartz geodes and nodular chert have been found within middle–upper Campanian carbonate sediments from the Laño and Tubilla del Agua sections of the Basque‐Cantabrian Basin, northern Spain. The morphology of geodes together with the presence of anhydrite laths included in megaquartz crystals and spherulitic fibrous quartz (quartzine‐lutecite), suggest an origin from previous anhydrite nodules. The anhydrite nodules at Laño were produced by the percolation of marine brines, during a period corresponding to a sedimentary gap, with δ³⁴S and δ¹⁸O mean values of 18.8‰ and 13.6‰ respectively, consistent with Upper Cretaceous seawater sulphate values. Higher δ³⁴S and δ¹⁸O mean values of 21.2‰ and 21.8‰ recorded in the Tubilla del Agua section are interpreted as being due to a partial bacterial sulphate reduction process in a more restricted marine environment. The idea that sulphates may have originated from the leaching of previously deposited Keuper sulphate evaporites with subsequent precipitation as anhydrite, is rejected because the δ³⁴S, δ¹⁸O and ⁸⁷Sr/⁸⁶Sr values of anhydrite laths observed at both the Tubilla del Agua and Laño sections suggest an origin from younger marine brines. Later calcite replacement and precipitation of geode‐filling calcite is recorded in both sections, with δ¹³C and δ¹⁸O values indicating the participation of meteoric waters. Synsedimentary activity of the Peñacerrada diapir, which lies close to the Laño section, played a significant role in the local shallowing of the basin and the formation of quartz geodes. In contrast, eustatic shallowing of the inner marine series of the Tubilla del Agua section led to the generation of morphologically similar quartz geodes. Copyright © 2002 John Wiley & Sons, Ltd.     

The hydrogeological and paleoclimatic factors in the Bronze Age Motillas Culture of La Mancha (Spain): the first hydraulic culture in Europe

Recent studies indicate that the motillas (Chalcolithic and Bronze Age settlements in La Mancha, Spain) could have constituted the most ancient groundwater collection system at regional scale in Europe. This paper presents the first hydrogeoarchaeological study at the regional level in La Mancha. The research includes borehole drilling and hydrogeological analysis of the territory on which the motillas are settled. The resulting data confirm a relationship between the geological substrate and the spatial distribution of the motillas, sited where groundwater was accessible by means of prehistoric technology. The motillas were built during the climatic event known as 4.2 ka cal BP, in a time of environmental stress after a period of severe and prolonged drought. In these environmental conditions, the construction of these wells was a successful solution that lived on for nearly a millennium and played a major part in the processes of change towards a more complex, hierarchical society.     

Spatial distribution, morphometry and activity of La Puebla de Alfindén sinkhole field in the Ebro river valley (NE Spain): applied aspects for hazard zonation

A highly active collapse sinkhole field in the evaporitic mantled karst of the Ebro river valley is studied (NE Spain). The subsidence is controlled by a NW-SE trending joint system and accelerated by the discharge of waste water from a nearby industrial state. The morphometry, spatial distribution and temporal evolution of the sinkholes have been analysed. The volume of the sinkholes yields a minimum estimate of average lowering of the surface by collapse subsidence of 46 cm. The clustering of the sinkholes and the tendency to form elongated uvalas and linear belts, in a NW–SE direction have a predictive utility and allow the establishment of criteria for a hazard zonation. With the precipitation record supplied by a pluviograph and periodic cartographic and photographic surveys the influence of heavy rainfall events on the triggering of collapses has been studied.     

Geochemistry and Sr, Nd, Pb isotopic composition of the Central Atlantic Magmatic Province (CAMP) in Guyana and Guinea

The Central Atlantic Magmatic Province (CAMP) is one of the largest igneous provinces on Earth, extending more than 5000 km north to south, on both sides of the Atlantic Ocean. Its emplacement occurred about 200 Ma ago, at the Triassic–Jurassic boundary, and is linked to the initial breakup of Pangaea. Two areas of the province are studied here: French Guyana/Surinam (South America) and Guinea (West Africa), in order to document the petrogenesis and geodynamical significance of high-Ti and low-Ti basaltic magmas from the CAMP.

In Guyana, doleritic and gabbroic dykes are located on the edge of the Guiana Shield, and represent limited volumes of magma. They display low SiO₂ (47–50%), high TiO₂ (2.5–3.5%) and high FeO tholeiitic trends and show variably enriched trace element patterns ((La/Yb)_n=1.5–5.1). Their isotopic signature and ratios of very incompatible elements (εNd_i=+5.8 to +4.2, (⁸⁷Sr/⁸⁶Sr)_i=0.703–0.705, (²⁰⁷Pb/²⁰⁴Pb)_i=15.46–15.64) match a depleted PREMA (prevalent mantle)-like source. Their genesis can be modeled by ca. 15% partial melting of a lherzolite source, and a subsequent limited fractional crystallization (5–10%) or a slight upper crustal assimilation–fractional crystallization (AFC, r=0.1, Proterozoic contaminant). In Guinea, in contrast, huge volumes of CAMP magmas were intruded along the Rockelides suture and the West African craton, forming the Fouta Djalon sills and the Kakoulima laccolith. The laccolith is more than 1000 m thick. These features consist of gabbros, dolerites, diorites and mafic (gabbro) and ultramafic (dunite, wherlite) cumulates. Guinean tholeiites show high SiO₂ (51–58%), low TiO₂ (0.7–1.2%) and FeO trends, with high LILE/HFSE ratios and slight negative Nb–Ta anomalies. Isotopic signatures (εNd_i=+0.4 to −5.3, (⁸⁷Sr/⁸⁶Sr)_i=0.705–0.710, (²⁰⁷Pb/²⁰⁴Pb)_i=15.57–15.66) indicate a more enriched source than for Guyana as well as a higher rate of magma–upper crust interaction through an AFC process (r=0.3, Birimian crust contaminant) and, probably, an additional upper crustal contamination for the most differentiated sample.

This geochemical study supports the prevalence in Guinea, as for other low-Ti CAMP tholeiites, of a lithospheric mantle source, previously enriched during ancient subduction events, and preferentially reactivated in late Triassic times by edge-driven convection between cratonic and mobile belt domains. A larger contribution from a depleted asthenospheric source is required to generate high-Ti tholeiites in Guyana, which may reflect the development of CAMP rifting towards the initiation of the Central Atlantic oceanic crust.     

Geological and Palaeontological context of three new Barremian (Lower Cretaceous) vertebrate sites in the Iberian Peninsula (Cuenca Province,Central Spain)

Three new Lower Cretaceous vertebrate sites (Vadillos-1, Vadillos-2, El Tobar) have been recently discovered and studied in the Cuenca Province (Central Spain). They are located in deposits of “Wealden” facies belonging to the El Collado Sandstone and Clay Formation. In these outcrops, micro and macroremains corresponding to plants, invertebrates and vertebrates have been collected and subsequently assigned to macrophytes, charophytes (e.g., Atopochara trivolvis triquetra, Globator maillardii trochiliscoides, Clavator harrisii harrisii), ostracods (e.g., Cypridea gr. modesta, Cypridea cf. C. isasae, Cypridea sp. aff. C. moneta, Cypridea sp. 1, Cypridea sp. 2), molluscs (Unionoida, Viviparus sp.), fishes, amphibians, turtles (cf. Eucryptodira), crocodyliforms (Neosuchia) and dinosaurs (ankylosaurs, ornithopods, theropods). Among the vertebrate remains, scales, teeth, plates, osteoderms, phalanges, ribs, vertebrae and other incomplete bones, as well as eggshell fragments have been identified. This rich and diverse assemblage was deposited in an upper Barremian alluvial-palustrine muddy floodplain crossed by braided sandy channels.     

Sources of very high heavy metal content in soils of volcanic island (La Réunion)

The objective of this study was to conduct an inventory of heavy metal concentrations (Cd, Cr, Cu, Hg, Ni, Pb and Zn) in the soils of La Réunion. 39 sampling sites were selected to cover the distribution of soils of the island. The results show that soils of La Réunion are rich in heavy metals: most of them exceed the French standard values beyond which sewage sludge spreading is not authorized. To identify the sources of heavy metals, we used: (i) the relationship between the heavy metal content in soils and the origin of the volcanic parent material; (ii) the comparison of heavy metal content between cultivated and uncultivated soils; and (iii) the heavy metal distribution in soil profiles. Cd and Pb evolution in soil profiles indicate an impact of human activities. High Hg concentrations in soils can be explained by the volcanic activity of the island. For Cr, Cu, Ni and Zn, we demonstrate that high concentrations in soils are mainly determined by the natural pedo-geochemical background.     

Organic petrology and geochemistry of the Carboniferous coal seams from the Central Asturian Coal Basin (NW Spain)

This paper presents for the first time a petrological and geochemical study of coals from the Central Asturian Coal Basin (North Spain) of Carboniferous (Pennsylvanian), mainly of Moscovian, age. A paleoenvironmental approach was used, taking into account both petrographic and organic geochemical studies. Vitrinite reflectance (R_r) ranges from 0.5% to 2.5%, which indicates a high volatile bituminous to semianthracite and anthracite coal rank. The coal samples selected for paleoenvironmental reconstruction are located inside the oil–gas-prone phase, corresponding to the interval between the onset of oil generation and first gas generation and efficient expulsion of oil. This phase is represented by coals that have retained their hydrocarbon potential and also preserved biomarker information. Paleodepositional reconstruction based on maceral and petrographic indices points to a swamp environment with vitrinite-rich coal facies and variable mineral matter content. The gelification index (GI) and groundwater influence index (GWI) indicate strong gelification and wet conditions. The biomarkers exhibit a high pristane/phytane ratio, suggesting an increase in this ratio from diagenetic processes, and a high diterpanes ratio. This, in turn, would seem to indicate a high swamp water table and a humid climate. The maximum point of coal accumulation occurred during the regressive part of the Late Moscovian sequence and in the most humid climate described for this period of time in the well-known coal basins of Europe and North America.     

Petrographic and geochemical evidence for the formation of primary, bacterially induced lacustrine dolomite: La Roda 'white earth' (Pliocene, central Spain)

Upper Pliocene dolomites (‘white earth’) from La Roda, Spain, offer a good opportunity to evaluate the process of dolomite formation in lakes. The relatively young nature of the deposits could allow a link between dolomites precipitated in modern lake systems and those present in older lacustrine formations. The La Roda Mg‐carbonates (dolomite unit) occur as a 3·5‐ to 4‐m‐thick package of poorly indurated, white, massive dolomite beds with interbedded thin deposits of porous carbonate displaying root and desiccation traces as well as local lenticular gypsum moulds. The massive dolomite beds consist mainly of loosely packed 1‐ to 2‐μm‐sized aggregates of dolomite crystals exhibiting poorly developed faces, which usually results in a subrounded morphology of the crystals. Minute rhombs of dolomite are sparse within the aggregates. Both knobbly textures and clumps of spherical bodies covering the crystal surfaces indicate that bacteria were involved in the formation of the dolomites. In addition, aggregates of euhedral dolomite crystals are usually present in some more clayey (sepiolite) interbeds. The thin porous carbonate (mostly dolomite) beds exhibit both euhedral and subrounded, bacterially induced dolomite crystals. The carbonate is mainly Ca‐dolomite (51–54 mol% CaCO₃), showing a low degree of ordering (degree of ordering ranges from 0·27 to 0·48). Calcite is present as a subordinate mineral in some samples. Sr, Mn and Fe contents show very low correlation coefficients with Mg/Ca ratios, whereas SiO₂ and K contents are highly correlated. δ¹⁸O‐ and δ¹³C‐values in dolomites range from ?3·07‰ to 5·40‰ PDB (mean=0·06, σ=1·75) and from ?6·34‰ to ?0·39‰ PDB (mean=?3·55, σ=1·33) respectively. Samples containing significant amounts of both dolomite and calcite do not in general show significant enrichment or depletion in ¹⁸O and ¹³C between the two minerals. The correlation coefficient between δ¹⁸O and δ¹³C for dolomite is extremely low and negative (r=?0·05), whereas it is higher and positive (r=0·47) for calcite. The lacustrine dolomite deposit from La Roda is interpreted mainly as a result of primary precipitation of dolomite in a shallow, hydrologically closed perennial lake. The lake was supplied by highly saturated HCO₃^?/CO₃^2? groundwater that leached dolomitic Mesozoic formations. Precipitation of dolomite from alkaline lake waters took place under a semi‐arid to arid climate. However, according to our isotopic data, strong evaporative conditions were not required for the formation of the La Roda dolomite. A significant contribution by bacteria to the formation of the dolomites is assumed in view of both petrographic and geochemical evidence.     

Lower Paleozoic rifting event in Central Iberian Zone (central-north Portugal): Evidence from elemental and isotopic geochemistry of metabasic rocks

The occurrence of Lower Paleozoic mafic magmatic rocks in the Central Iberian Zone (CIZ) of the Variscan Orogen is rare. Amphibolites and metagabbros embedded in the metasediments of the Douro-Beiras Supergroup outcrop at Farminhão, Viseu (central-north Portugal). The protoliths of these two rock types are tholeiites presenting different isotopic signatures (εNd₄₈₀ = +4.63 to +4.93 and +5.74 to +7.67) and incompatible element ratios (normalized La/Lu up to 4.5 and down to 0.7), respectively which suggests they are not cogenetic. The closely related meta-ultramafic rocks are considered as cumulates generated from the magmas that originated the metagabbros. The elemental and isotopic features of the metagabbros are similar to those reported for amphibolitic occurrences in Tenzuela (near Segovia, Spain) which allows the proposition of a similar age for the mafic rocks of Farminhão. Despite the depleted characteristics of the studied rocks, they are interpreted as having been formed during a continental rifting process characterized by variable degrees of stretching, some 100 Ma after the end of the deposition of the Douro-Beiras Supergroup. This rifting event marks the onset of the Variscan Cycle (s.l.) in the Central Iberian Zone. The occurrence of these metabasic rocks near the confluence between the Porto-Viseu Metamorphic Belt and the Juzbado-Penalva do Castelo Shear Zone suggests that these first-order structures may have worked as weakness zones constraining the ascent of magmas during the Ordovician. The Lower Ordovician metabasic rocks here studied are chemically similar to the abundant lower to medium Cambrian magmatic rocks of the Ossa Morena Zone, also in Iberia, further reinforcing the diachronous character of the opening of the Rheic Ocean that later propagated to the eastern sectors of the European Variscan Belt.     

Constraining the age of the last marine sediments in the late Cretaceous of central south Pyrenees (NE Spain): Insights from larger benthic foraminifera and strontium isotope stratigraphy

The uppermost Cretaceous (upper Campanian–Maastrichtian) marine deposits of the central south Pyrenees host a rich larger benthic foraminiferal fauna and several rudist-rich levels. These marine deposits are directly overlain by the continental facies of the Arén and Tremp Formations, which are famous for their fossil dinosaur remains. Larger benthic foraminiferal distribution documents an important faunal turnover in all the carbonate platform environments within the photic zone, from open marine to littoral areas. Biostratigraphy indicates that this turnover occurred close to the Campanian-Maastrichtian boundary. This is also confirmed by strontium isotope stratigraphy which indicates an earliest Maastrichtian age for the appearance of the larger benthic foraminiferal assemblage constituted by Lepidorbitoides socialis, Clypeorbis mammillata, Wannierina cataluniensis, Orbitoides gruenbachensis, Siderolites aff. calcitrapoides, Fascispira colomi, Omphalocyclus macroporus and Laffiteina mengaudi. In particular, a numerical age of 71 Ma is obtained for the Hippurites radiosus level, just a few meters below the first continental deposits of the Arén sensu stricto Formation. The youngest marine sediments of the central south Pyrenees are early Maastrichtian in age. This is also an important constraint for the age of the end-Cretaceous dinosaur fossil localities of the Tremp basin.     

Temporal and spatial variations in tectonic subsidence in the Iberian Basin (eastern Spain): inferences from automated forward modelling of high-resolution stratigraphy (Permian–Mesozoic)

By subsidence analysis on eighteen surface sections and 6 wells, which cover large part of the Iberian Basin (E Spain) and which are marked by high-resolution stratigraphy of the Permian, Triassic, Jurassic and Cretaceous, we quantify the complex Permian and Mesozoic tectonic subsidence history of the basin. Backstripping analysis of the available high resolution and high surface density of the database allows to quantify spatial and temporal patterns of tectonically driven subsidence to a much higher degree than previous studies. The sections and wells have also been forward modelled with a new ‘automated' modelling technique, with unlimited number of stretching phases, in order to quantify variations in timing and magnitude of rifting. It is demonstrated that the tectonic subsidence history in the Iberian Basin is characterized by pulsating periods of stretching intermitted by periods of relative tectonic quiescence and thermal subsidence. The number of stretching phases appears to be much larger than found by earlier studies, showing a close match with stretching phases found in other parts of the Iberian Peninsula and allowing a clear correlation with discrete phases in the opening of the Tethys and Atlantic.     

内蒙古白乃庙地区铜(金)和金矿床钕、锶和铅同位素研究

内自古白乃庙地区产出有白乃庙铜（金）矿床（南、北矿带）、白乃庙金矿床和徐尼乌苏金矿化带，是华北陆台北缘金属成矿带的重要组成部分。笔者测定和解释了上述三个矿床的钕、锶和铅同位素比值和变化特征。研究认为：白乃庙铜（金）矿床南、北矿带在成矿时代、成矿物质来源和形皮过程方面存在明显差异，南矿带条带状、块状硫化物矿石的形成作用始于１１３０×１０￣６ａ前的基性火山喷发活动。相比之下，北矿带细脉浸染状和脉状铜－钼－金矿石与加里东期（４４０×１０￣６ａ）花岗闪长斑岩的侵位和结晶分异密切相关。白乃庙金矿床和徐尼乌苏金矿化带是岩浆热液、大气降水混合，并且对基底岩层或绿片岩围岩进行淋滤、萃取的结果。白乃庙地区铜（金）矿床和金矿床（点）成矿物质来源和形成机制的厘定，对于了解华北地台北缘内蒙古中南段金属成矿带的形成与演化具有重要意义。     

渭河盆地始新世-渐新世沉积物源变化的钻探样品Sr和Nd同位素证据

始新世暖期和始新世-渐新世降温阶段（EOT）在地球气候系统演化中具有代表性,对认识现代全球变暖过程和机制有参考价值。渭河盆地堆积了始新世以来连续的河湖相沉积序列,对其进行沉积物源示踪研究有助于重建渭河流域地貌演化、沉积过程和气候环境变化。本研究对渭河盆地新生代沉积中心固市凹陷荔参1井（钻探井深6535 m）下部的始新世红河组（6527~5529 m）和渐新世白鹿塬组（5315~4759 m）样品进行了Sr和Nd同位素分析,探索古近纪渭河盆地的物源变化过程。结果显示,红河组样品Sr和Nd同位素平均值分别是⁸⁷Sr/⁸⁶Sr=0.716127和ε_Nd=-13.5,白鹿塬组Sr和Nd同位素平均值分别是⁸⁷Sr/⁸⁶Sr=0.720461和ε_Nd=-12.4。分粒级（< 2 μm,2~64 μm和>64 μm）Sr和Nd同位素测试结果表明,粒度效应对渭河盆地始新世-渐新世沉积物硅酸盐矿物的Sr同位素值影响较大,而对Nd同位素影响较小,表明硅酸盐矿物Nd同位素值可作为渭河盆地沉积物物源的指示。结合潜在源区Sr和Nd同位素分布特征,发现渭河盆地始新世和渐新世沉积物主要来自于秦岭造山带和鄂尔多斯地块的贡献,其物源变化与构造抬升和气候演变密切相关。渭河盆地始新世和渐新世沉积物传输和堆积过程与晚新生代相似,具有相对稳定的两端元物源,为利用红河组和白鹿塬组沉积序列重建古气候古环境奠定了良好的基础。

     

High strontium contents and Sr/Ca-ratios in Lake Constance waters and carbonates and their sources in the drainage area of the Rhine River (Alpenrhein)

Algal and mollusk carbonates in Lake Constance sediments proved Sr/Ca-ratios unusually high for fresh water environments. In most cases the observed Sr/Ca-ratios for mollusk shells fall into the range of marine mollusks. These high ratios can be attributed to a high Sr/Ca-ratio (6 ± 0.5) in Lake Constance water. In the Alpenrhein River, the main influent of Lake Constance, Sr/Ca-ratios were found to vary between 4.7 (at high water discharge) and 10.7 (at low water level). High Sr/Ca-ratios correspond to high sulfate contents. From all tributaries of the Alpenrhein, the Ill River revealed to have the highest Sr-contents and Sr/Ca-ratios. A detailed study of its drainage area led to the detection of exceptionally high Sr-contents (up to 11.6 mg/l) and Sr/Ca-ratios (up to 116.5) in springs of the Triassic Ladinian stage of the Austroalpine nappe zone (Ostalpine Deckenzone). The fact that high Sr-concentrations occur together with high sulfate contents leads to the assumption that celestite is leached within Ladinian rocks. This assumption is confirmed by the evidence that celestite deposits have been reported from the same stratigraphic section (Wettersteinkalk) from other localities in the Northern Calcareous Alps.

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Zusammenfassung In Bodensee-Sedimenten auftretende biogene Carbonate zeigen ein für Süßwasserbildungen ungewöhnlich hohes Sr/Ca-Verhältnis; die meisten bei Mollusken gefundenen Werte fallen in den marinen Bildungsbereich. Diese hohen Sr/Ca-Verhältnisse können durch das hohe Sr/Ca-Verhältnis des Bodenseewassers (6 ± 0,5) gedeutet werden, das seinerseits vom noch höheren Sr/Ca-Verhältnis des wichtigsten Zuflusses, des Alpenrheins (4,7 bei Hochwasser, 10,7 bei Niedrigwasser) geprägt wird. Hohe Sr/Ca-Verhältnisse fallen mit hohen Sulfatgehalten zusammen. Von allen Nebenflüssen des Alpenrheins zeigt die Ill die höchsten Sr-Gehalte und Sr/Ca-Verhältnisse. Eine Untersuchung des Einzugsgebietes der Ill führte zur Auffindung von Bächen und Quellen mit ungewöhnlich hohen Sr-Gehalten (bis 11,6 mg/l) und Sr/Ca-Verhältnissen (bis 116,5), die im Ladin der Alpinen Trias der Ostalpinen Deckenzone entspringen. Da hohe Konzentrationen mit hohen Sulfatgehalten zusammenfallen, kann angenommen werden, daß Coelestin aus Gesteinen des Ladins ausgelaugt wird und die hohen Sr/Ca-Verhältnisse der Wässer bedingt. Diese Annahme wird durch die Tatsache erhärtet, daß Coelestin im gleichen stratigraphischen Horizont (Wettersteinkalk) an mehreren anderen Stellen der Nördlichen Kalkalpen beobachtet wurde.