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Deposit guarantee schemes : a European perspective
\"Deposit guarantee schemes are a crucial element of modern financial safety nets. Despite positive achievements in the integration of European financial markets and economies, the recent financial crisis confirmed that closer coordination of prudential policies and safety nets is now required. Against this background, Francesca Arnaboldi highlights the importance of one of the three pillars of the Banking Union, the common mechanism for insuring deposits. She suggests that integrated financial markets require a European solution with regard to deposit insurance and that the establishment of a pan-European scheme could address the problems for large cross-border banks. The book is an ideal resource for academics and practitioners interested in the new regulatory framework on deposit guarantee schemes and its link to the first two pillars of the Banking Union. \"-- Provided by publisher.
Book
The trace-element compositions of amphibole, magnetite and ilmenite as potential exploration guides to metamorphosed Proterozoic Cu-Zn±Pb±Au±Ag volcanogenic massive sulfide deposits in Colorado, USA
Orthoamphibole, clinoamphibole and magnetite are common minerals in altered rocks associated spatially with Palaeoproterozoic volcanogenic massive sulfide (VMS) deposits in Colorado, USA and metamorphosed to the amphibolite facies. These altered rocks are dominated by the assemblage orthoamphibole (anthophyllite/gedrite)-cordierite-magnetite±gahnite±sulfides. Magnetite also occurs in granitoids, banded iron formations, quartz garnetite, and in metallic mineralisation consisting of semi-massive pyrite, pyrrhotite, chalcopyrite, and sphalerite with subordinate galena, gahnite and magnetite; amphibole also occurs in amphibolite. The precursor to the anthophyllite/gedrite-cordierite assemblages was probably the assemblage quartz-chlorite formed from hydrothermal ore-bearing fluids (∼250° to 400°C) associated with the formation of metallic minerals in the massive sulfide deposits. Element-element variation diagrams for amphibole, magnetite and ilmenite based on LA-ICP-MS data and Principal Component Analysis (PCA) for orthoamphiboles and magnetite show a broad range of compositions which are primarily dependent upon the nature of the host rock associated spatially with the deposits. Although discrimination plots of Al/(Zn+Ca) vs Cu/(Si+Ca) and Sn/Ga vs Al/Co for magnetite do not indicate a VMS origin, the concentration of Al+Mn together with Ti+V and Sn vs Ti support a hydrothermal rather than a magmatic origin for magnetite. Principal Component Analyses also show that magnetite and orthoamphibole in metamorphosed altered rocks and sulfide zones have distinctive eigenvalues that allow them to be used as prospective pathfinders for VMS deposits in Colorado. This, in conjunction with the contents of Zn and Al in magnetite, Zn and Pb in amphibole, ilmenite and magnetite, the Cu content of orthoamphibole and ilmenite, and possibly the Ga and Sn concentrations of magnetite constitute effective exploration vectors.
Journal Article
Sulfide-silicate textures in magmatic Ni-Cu-PGE sulfide ore deposits; disseminated and net-textured ores
A large proportion of ores in magmatic sulfide deposits consist of mixtures of cumulus silicate minerals, sulfide liquid, and silicate melt, with characteristic textural relationships that provide essential clues to their origin. Within silicate-sulfide cumulates, there is a range of sulfide abundance in magmatic-textured silicate-sulfide ores between ores with up to about five modal percent sulfides, called \"disseminated ores,\" and \"net-textured\" (or \"matrix\") ores containing about 30 to 70 modal percent sulfide forming continuous networks enclosing cumulus silicates. Disseminated ores in cumulates have various textural types relating to the presence or absence of trapped interstitial silicate melt and (rarely) vapor bubbles. Spherical or oblate spherical globules with smooth menisci, as in the Black Swan disseminated ores, are associated with silicate-filled cavities interpreted as amygdales or segregation vesicles. More irregular globules lacking internal differentiation and having partially facetted margins are interpreted as entrainment of previously segregated, partially solidified sulfide. There is a textural continuum between various types of disseminated and net-textured ores, intermediate types commonly taking the form of \"patchy net-textured ores\" containing sulfide-rich and sulfide-poor domains at centimeter to decimeter scale. These textures are ascribed primarily to the process of sulfide percolation, itself triggered by the process of competitive wetting whereby the silicate melt preferentially wets silicate crystal surfaces. The process is self-reinforcing as sulfide migration causes sulfide networks to grow by coalescence, with a larger rise height and hence a greater gravitational driving force for percolation and silicate melt displacement. Many of the textural variants catalogued here, including poikilitic or leopard-textured ores, can be explained in these terms. Additional complexity is added by factors such as the presence of oikocrysts and segregation of sulfide liquid during strain-rate dependent thixotropic behavior of partially consolidated cumulates. Integrated textural and geochemical studies are critical to full understanding of ore-forming systems.
Journal Article
The genesis of metamorphosed Paleoproterozoic massive sulphide occurrences in central Colorado; geological, mineralogical and sulphur isotope constraints
Paleoproterozoic massive Cu-Zn±Pb±Au±Ag sulphide deposits metamorphosed to the middle-upper amphibolite facies in central-south Colorado formed in a volcanic arc setting on the edge of the Yavapai crustal province. Previously published U-Pb ages on spatially related granitoids range from ∼1.9 to ∼1.1 Ga, while Pb isotope studies on galena from massive sulphides suggest mineralization formed at around 1.8-1.7 Ga. Some deposits in the Dawson-Green Mountain trend (DGMT) and the Gunnison belt are composed of Cu-Zn-Au-(Pb-Ag) mineralization that were overprinted by later Au-(Ag-Cu-Bi-Se-Te) mineralization. Sulphide mineralization is spatially related to amphibolite and bimodal, mafic-felsic volcanic rocks (gabbro, amphibolite, rhyolite and dacite) and granitoids, but it occurs mostly in biotite-garnet-quartz±sillimanite±cordierite schists and gneisses, spatially related to nodular sillimanite rocks, and in some locations, exhalative rocks (iron formations, gahnite-rich rocks and quartz-garnetite). The major metallic minerals of the massive sulphides include chalcopyrite, sphalerite, pyrite, pyrrhotite, and magnetite, with minor galena and gahnite. Altered rocks intimately associated with mineralization primarily consist of various amphiboles (gedrite, tremolite and hornblende), gahnite, biotite, garnet, cordierite, carbonate and rare högbomite. The Zn/Cd ratios of sphalerite (44 to 307) in deposits in the DGMT fall within the range of global volcanogenic massive sulphide (VMS) deposits but overlap with sphalerite from sedimentary exhalative (Sedex) deposits. Sulphur isotope values of sulphides (δ34S = -3.3 to +6.5) suggest sulphur was largely derived from magmatic sources, and that variations in isotopic values resulting from thermochemical sulphate reduction are due to small differences in physicochemical conditions. The preferred genetic model is for the deposits to be bimodal-mafic (Gunnison) to mafic-siliciclastic VMS deposits (Cotopaxi, Cinderella-Bon Ton, DGMT).
Journal Article
A stable isotope (S, C and O) study of metamorphosed polymetallic sulphide deposits in the Bergslagen district, Sweden: The Stollberg example
The Paleoproterozoic Stollberg Zn-Pb-Ag plus magnetite ore field contains SVALS-type stratabound, limestone-skarn hosted sulphide deposits within volcanic (bimodal felsic and mafic rocks)/volcaniclastic rocks metamorphosed to the amphibolite facies. The sulphide ores consist of semi-massive to disseminated to vein-network sphalerite-galena and pyrrhotite (with subordinate pyrite, chalcopyrite, arsenopyrite and magnetite). Thermochemical considerations and stabilities of minerals in the systems K-Al-Si-O-H and Fe-S-O and sulphur isotope values for sulphides of δ34SVCDT = +1.12 to +5.71 ‰ suggest that sulphur most likely formed by inorganic reduction of seawater sulphate that was carried in hydrothermally modified seawater fluid under the following approximate physicochemical conditions: T = 250o–350 oC, δ34SΣS = +3 ‰, I = ∼1 m NaCl and a total dissolved S content of ∼0.01 to 0.1 moles/kg H2O. However, a magmatic contribution of sulphur cannot be discounted. Carbon and oxygen isotope compositions of calcite in altered rocks spatially associated with mineralisation show values of δ13CVPDB = −2.3 to −0.8 ‰ and δ18OVSMOW = +9.5 to +11.2 ‰, with one anomalous sample exhibiting values of δ13CVPDB = −0.1 ‰ and δ18OVSMOW = +10.9 ‰. Most carbonates in ore show lighter C and O isotope values than those of Proterozoic (Orosirian) limestones and are likely the result of premetamorphic hydrothermal alteration involving modified seawater followed by decarbonation during regional metamorphism. The isotopically light C and O isotope values are consistent with those for carbonates spatially associated with other SVALS-type deposits in the Bergslagen ore district and suggest that such values may be used for exploration purposes.
Journal Article
The Use of Blanket Guarantees in Banking Crises
In episodes of significant banking distress or perceived systemic risk to the financial system, policymakers have often opted for issuing blanket guarantees on bank liabilities to stop or avoid widespread bank runs. In theory, blanket guarantees can prevent bank runs if they are credible. However, guarantee could add substantial fiscal costs to bank restructuring programs and may increase moral hazard going forward. Using a sample of 42 episodes of banking crises, this paper finds that blanket guarantees are successful in reducing liquidity pressures on banks arising from deposit withdrawals. However, banks' foreign liabilities appear virtually irresponsive to blanket guarantees. Furthermore, guarantees tend to be fiscally costly, though this positive association arises in large part because guarantees tend to be employed in conjunction with extensive liquidity support and when crises are severe.
eBook
The role of clay minerals in formation of the regolith-hosted heavy rare earth element deposits
Rare earth elements (REEs) have become increasingly important to our modern society due to their strategic significance and numerous high technological applications. Regolith-hosted heavy rare earth element (HREE) deposits in South China are currently the main source of the HREEs, but the ore-forming processes are poorly understood. In these deposits, the REEs are postulated to accumulate in regolith through adsorption on clay minerals. In the Zudong deposit, the world's largest regolith-hosted HREE deposit, clay minerals are dominated by short, stubby, nanometer-scale halloysite tubes (either 10 or 7 Å) and microcrystalline kaolinite in the saprolite and lower pedolith and micrometer-sized vermicular kaolinite in the humic layer and upper pedolith. A critical transformation of the clay minerals in the upper pedolith is coalescence and unrolling of halloysite to form vermicular kaolinite. Microcrystalline kaolinite also transformed to large, well-crystalline vermicular kaolinite. This transformation could result in significant changes in different physicochemical properties of the clay assemblages. Halloysite-abundant clay assemblages in the deep regolith have specific surface area and porosity significantly higher than the kaolinite-dominant clay assemblages in the shallow soils. The crystallinity of clay minerals also increased, exemplified by decrease in Fe contents of the kaolinite group minerals (from ∼1.2 wt% in the lower saprolite to ∼0.35 wt% in the upper pedolith), thereby indicative of less availability of various types of adsorption sites. Hence, halloysite-abundant clay minerals of high adsorption capacity in deep regolith could efficiently retain the REEs released from weathering of the parent granite. Reduction in adsorption capacity during the clay transformation in shallow depth partially leads to REE desorption, and the released REEs would be subsequently transported to and adsorbed at deeper part of the soil profile. Hence, the clay-adsorbed REE concentration in the lower pedolith and saprolite (∼2500 ppm on average) is much higher than the uppermost soils (∼400 ppm on average). Therefore, weathering environments that favor the release of the REEs in the shallow soils but preservation of halloysite in the deep regolith can continuously adsorb REEs in the clay minerals to form economically valuable deposits.
Journal Article