Evaluation of site effects using numerical and experimental analyses in Città di Castello (Italy)

In the paper the results of the numerical and experimental analyses, at a site in the Umbria Region (Città di Castello—PG), are finalized and the evaluations of site effects are shown. The aim of the work was to compare the two types of analyses and give some methodologies that may be used at the level of urban planning. Therefore a series of geological, geomorphological (1:5.000 scale), geotechnical and seismic analyses have been carried out, to characterize the lithological units and to identify the areas affected by site effects. The expected seismic inputs were provided and two-dimensional numerical analyses have been done. An experimental analysis, using the registrations of small events, has been done. The results for the two approaches were performed in terms of elastic pseudo-acceleration spectra and amplification factors. The results are given as a ratio between spectral intensity, calculated using the pseudo-velocity spectra, in the periods of 0.1–0.5 s and 0.1–2.5 s of output and input. The results have been analyzed and compared, to provide a methodology that may be comprehensive and precise.     

Geology and D-O-C Isotope Systematics of the Tieluping Silver Deposit,Henan, China: Implications for Ore Genesis

The Tieluping silver deposit, which is sited along NE-trending faults within the high-grade metamorphic basement of the Xiong‘er terrane, is part of an important Mesozoic orogenic-type Ag-Pb and Au belt recently discovered. Ore formation includes three stages: Early (E), Middle (M) and Late (L), which include quartz-pyrite (E),polymetallic sulfides (M) and carbonates (L), respectively. The E-stage fluids are characterized by δD=-90%c,δ^13CCO2=2.0‰ and δ^18O=9‰ at 373℃, and are deeply sourced; the L-stage fluids, with δD=-70‰, δ^13C CO2=-1.3%c and δ^18O=-2‰, are shallow-sourced meteoric water; whereas the M-stage fluids, with δD=-109‰, δ^13C CO2=0.1%c and δ^18O2‰, are a mix of deep-sourced and shallow-sourced fluids. Comparisons of the D-O-C isotopic systematics of the Estage ore-forming fluids with the fluids derived from Mesozoic granites, Archean-Paleoproterozoic metamorphic basement and Paleo-Mesoproterozoic Xiong‘er Group, show that these units cannot generate fluids with the measured isotopic composition (high δ^180 and δ^13C ratios and low δD ratios) characteristic of the ore-forming fluids. This suggests that the E-stage ore-forming fluids originated from metamorphic devolatilization of a carbonate-shale-chert lithological association, locally rich in organic matter, which could correspond to the Meso-Neoproterozoic Guandaokou and Luanchuan Groups, rather than to geologic units in the Xiong‘er terrane, the lower crust and the mantle. This supports the view that the rocks of the Guandaokou and Luanchuan Groups south of the Machaoying fault might be the favorable sources. A tectonic model that combines collisional orogeny, metallogeny and hydrothermal fluid flow is proposed to explain the formation of the Tieluping silver deposit. During the Mesozoic collision between the South and North China paleocontinents, a crustal slab containing a lithological association consisting of carbonate-shale-chert, locally rich in organic matter (carbonaceous shale) was thrust northwards beneath the Xiong‘er terrane along the Machaoying fault.Metamorphic devolatilization of this underthrust slab provided the ore-forming fluids to develop the Au-Ag-(Pb-Zn) ore belt, which includes the Tieluping silver deposit.     

Amplification of strong ground motion in the city of Zagreb, Croatia, estimated by computation of synthetic seismograms

A hybrid technique consisting of modal summation and subsequent finite differences modelling is applied for the computation of synthetic accelerograms along a profile crossing the city of Zagreb, the capital of Croatia. Assuming the source geometry is known, the amplification properties of the underlying soil may be determined by comparison of synthetics and their response spectra computed for a bedrock model with the ones obtained under the assumption of a realistic laterally varying local model. The peak ground acceleration is larger by a factor of up to 3.5 than the value obtained for the bedrock model. The amplification of the response spectra is most prominent for frequencies below 2 Hz, and increases sharply to the SW from the mapped fault running through the centre of the city.     

Interval velocity and thickness estimate from wide-angle reflection data

A method to estimate interval velocities and thickness in a horizontal isotropic layered medium from wide-angle reflection traveltime curves is presented. The method is based on a relationship between the squared reflection traveltime differences and the squared offset differences relative to two adjacent reflectors. The envelope of the squared-time versus offset-difference curves, for rays with the same ray parameter, is a straight line, whose slope is the inverse of the square of the interval velocity and whose intercept is the square of the interval time. The method yields velocity and thickness estimates without any knowledge of the overlying stratification. It can be applied to wide-angle reflection data when either information on the upper crust and/or refraction control on the velocity is not available. Application to synthetic and real data shows that the method, used together with other methods, allows us to define a reliable 1D starting model for estimating a depth profile using either ray tracing or another technique.     

The origin of thermal waters from the eastern flank of the Dead Sea Rift Valley (western Jordan)

Thermal waters emerging along the eastern flank of the northernmost part of the Dead Sea Rift Valley close to the Yarmuk river are dilute, Ca–SO₄–(HCO₃) and Na–Cl water types with measured temperatures of 35–60 °C and estimated teperatures, according to silica solubility, of 60–110 °C. They are fed only by present‐day recharged meteoric waters (Wadi Hasa, Al Himma and North Shuna thermal baths) and by meteoric waters contaminated with saline waters (El Ma'in thermal Bath). Although they have been known for a long time, there is still dispute about their origins and the source of heat. On the basis of new chemical and isotopic analyses, the saline waters could represent residual pockets of groundwater in equilibrium with those filling the Dead Sea depression before the last retreat of Lake Lisan at 17–15 kyr bp or with the ancient seawaters of the Sedom Lagoon in the early Pleistocene, in both cases unaffected by significant evaporation processes but chemically and isotopically modified by water/rock interaction.     

Gold and silver metallogeny of the South China Fold Belt: a consequence of multiple mineralizing events?

The South China Fold Belt is part of the South China Block that is interpreted to be the result of multiple tectonic and magmatic events that formed a collage of accreted Proterozoic and Phanerozoic terranes. The Jurassic to early Cretaceous Yanshanian period (180–90 Ma), a time of major tectono-thermal events that affected much of eastern and southeastern China, is of great metallogenic importance in the fold belt. This period is linked to subduction of the Pacific plate beneath the Eurasian continent, and is manifested by voluminous volcano-plutonic activity of predominantly calc-alkaline affinity.The distribution of gold and silver deposits in the South China Fold Belt indicates the presence of two distinct metallogenic provinces. A region of basement uplifts, which are controlled by shear zones and form Neoproterozoic inliers of metamorphosed iron-rich rock types, defines the first province. In this province, orogenic lodes and volcanic-related epithermal deposits represent the more significant precious-metal mineralization. The second province is essentially confined to a belt of Yanshanian felsic–intermediate volcanic and subvolcanic rocks that extends along most of the southeastern China coast in an area known as the Coastal Volcanic Belt. Deposits in the Coastal Volcanic Belt are silver- and/or copper-rich, volcanic-hosted and epithermal in character.The precious-metal metallogeny of the South China Fold Belt is interpreted to have developed in at least three stages: one as a result of collision events, during the Caledonian Orogeny (ca. 400 Ma), the second during the Indosinian Orogeny (ca. 200 Ma) and the third during or soon after the formation of the Yanshanian magmatic belt (Yanshanian Orogeny; 180–90 Ma). The latter was responsible for a hydrothermal event that affected large sections of the belt and its Proterozoic substrate. This may have resulted in the redistribution and enrichment of precious metals from preexisting orogenic gold lodes in Neoproterozoic basement rocks, which are now exposed as windows in zones of tectonic uplift. The Yanshanian hydrothermal activity was particularly widespread in the Coastal Volcanic Belt and resulted in the formation of both low- and high-sulfidation epithermal gold and silver, and locally copper and other base-metal mineralization. It is suggested that the Coastal Volcanic Belt has greater potential for world-class epithermal and porphyry deposits than previously realised.     

Ivrea seismic array: a study of continental crust and upper mantle

A seismic-array study of the continental crust and upper mantle in the Ivrea-Yerbano and Strona-Ceneri zones (northwestern Italy) is presented. A short-period network is used to define crustal P - and S -wave velocity models from earthquakes. The analysis of the seismic-refraction profile LOND of the CROP-ECORS project provided independent information and control on the array-data interpretation.
Apparent-velocity measurements from both local and regional earthquakes, and time-term analysis are used to estimate the velocity in the lower crust and in the upper mantle. The geometry of the upper-lower crust and Moho boundaries is determined from the station delay times.
We have obtained a three-layer crustal seismic model. The P -wave velocity in the upper crust, lower crust and upper mantle is 6.1±0.2 km s⁻¹, 6.5±0.3 km s⁻¹ and 7.8±0.3 km s⁻¹ respectively. Pronounced low-velocity zones in the upper and lower crust are not observed. A clear change in the velocity structure between the upper and lower crust is documented, constraining the petrological interpretation of the Ivrea-type reflective lower continental crust derived from small-scale petrophysical data. Moreover, we found a V _P/ V _S ratio of 1.69±0.04 for the upper crust and 1.82±0.08 for the lower crust and upper mantle. This is consistent with the structural and petrophysical differences between a compositionally uniform and seismically transparent upper crust and a layered and reflective lower crust. The thickness of the lower crust ranges from about 8 km in front of the Ivrea body (ARVO, Arvonio station) in the northern part of the array to a maximum of about 15 km in the southern part of the array. The lower crust reaches a minimum depth of 5 km below the PROV (Provola) station.     

中等传输距离下的无线功率传输链路第2部分:选择性工作方式

对谐振感应式无线功率传输链路的3种不同的工作方式进行了讨论.第1种工作方式是输出恒定的电压或电流;第2种工作方式采用频率捷变操作,非常适合于不随耦合系数变化的应用场合;第3种工作方式实现负载独立工作并输出恒定的电压或电流.本文讨论并提出了不同情况下的解决方案和相关公式.最后通过实验对提出的理论进行了验证.     

Photoelectric photometry and rotation periods of the asteroids 26 Proserpina, 194 Prokne, 287 Nephthys,and 554 Peraga

We present the photoelectric observations of the asteroids 26 Proserpina, 194 Prokne, 287 Nephthys, and 554 Peraga, performed in the years 1977–1978 at the Astronomical Observatory of Torino. The resulting synodic rotation periods are, for Proserpina, 13^h13; Prokne, 15^h67; and Peraga, 13^h63. The period of Nephthys is possibly ～7^h or the double. A tentative value for the phase coefficient of Peraga was found: 0.043 mag/degree.