980 resultados para ash deposit
Resumo:
It is generally agreed that a Banking Union should have common or ‘single’ institutions responsible for carrying out three basic functions: supervision, resolution and deposit insurance. So far, however, agreement has been reached in the EU on only the first two of these functions. The Commission has now presented its proposal on how to complete the Banking Union with a European Deposit Insurance Scheme (EDIS). It is an innovative and courageous proposal. It is courageous because it will clearly be very controversial in a number of member states (especially Germany) and it is innovative because it proposes a three-stage process, starting with re-insurance, then switching to co-insurance and finally to full direct insurance of deposits via a ‘single’ Deposit Insurance Fund (DIF). This final stage should be reached in 2024, which is also the date at which the Single Resolution Fund (SRF) will become the only source of financing for bank resolution. The Commission’s proposal calls for integrating the decision-making for EDIS into the decision-making entity for the SRF, namely the existing Single Resolution Board (SRB). This makes sense if one views resolution and deposit insurance as two highly interlinked dimensions of dealing with banks in trouble. In this view the two dimensions should be bundled into one institution – and one suspects that over time the two funds (the SRF and the DIF) could be merged into one. This Policy Brief argues that re-insurance should not be considered as a transitory phase, but could also provide a solution for the long run. ‘Experience rating’ could be used to ensure a proper pricing of risk and to protect the interests of the depositors in countries with safer banking systems. Moreover, EDIS should have a decision-making structure separate from and independent of the SRM, since it has mainly a macroeconomic function.
Resumo:
Three types of tephra deposits were recovered on Leg 65 of the Deep Sea Drilling Project (DSDP) from three drill sites at the mouth of the Gulf of California: (1) a series of white ash layers at Sites 483, 484, and 485; (2) a layer of plagioclase- phyric sideromelane shards at Site 483; and (3) an indurated, cross-bedded hyaloclastite in Hole 483B. The ash layers in (1) are composed of colorless, fresh rhyolitic glass shards with minor dacitic and rare basaltic shards. These are thought to be derived from explosive volcanoes on the Mexican mainland. Most of the shards in (2) are fresh, but some show marginal to complete alteration to palagonite. The composition of the glass is that of a MORB-type tholeiite, low in Fe and moderately high in Ti, and possibly erupted from off-axis seamounts. Basaltic glass shards occurring in silt about 45 meters above the basement at Site 484 A in the Tamayo Fracture Zone show a distinctly alkalic composition similar to that of the single basement basalt specimen drilled at this site. The hyaloclastite in (3) is made up chiefly of angular sideromelane shards altered to smectite and zeolites (mainly phillipsite) and minor admixtures of terrigenous silt. A very high K and Ba content indicates significant uptake of at least these elements from seawater. Nevertheless, the unusual chemical composition of the underlying massive basalt flow is believed to be reflected in that of the hyaloclastite. This is a powerful argument for interpreting the massive basalt as a surface flow rather than an intrusion. Glass alteration is different in the glassy margins of flows than in thicker glassy pillow rinds. Also, it appears to proceed faster in coarse- than fine-grained sediments.
Resumo:
The McMurdo Dry Valleys, Antarctica (MDV) are among the oldest landscapes on Earth, and some landforms there present an intriguing apparent contradiction such that millions of years old surface deposits maintain their meter-scale morphology despite the fact that measured erosion rates are 0.1-4 m/Ma. We analyzed the concentration of cosmic ray-produced 10Be and 26Al in quartz sands from regolith directly above and below two well-documented ash deposits in the MDV, the Arena Valley ash (40Ar/39Ar age of 4.33 Ma) and the Hart ash (K-Ar age of 3.9 Ma). Measured concentrations of 10Be and 26Al are significantly less than expected given the age of the in situ air fall ashes and are best interpreted as reflecting the degradation rate of the overlying sediments. The erosion rate of the material above the Arena Valley ash that best explains the observed isotope profiles is 3.5 ± 0.41 x 10**-5 g/cm**2/yr (~0.19 m/Ma) for the past ~4 Ma. For the Hart ash, the erosion rate is 4.8 ± 0.21 x 10**-4 g/cm**2/yr (~2.6 m/Ma) for the past ~1 Ma. The concentration profiles do not show signs of mixing, creep, or deflation caused by sublimation of ground ice. These results indicate that the slow, steady lowering of the surface without vertical mixing may allow landforms to maintain their meter-scale morphology even though they are actively eroding.