High-resolution teleseismic body-wave tomography beneath SE Romania – I. Implications for three-dimensional versus one-dimensional crustal correction strategies with a new crustal velocity model     

M. Martin  J. R. R. Ritter  the CALIXTO working group 《Geophysical Journal International》2005,162(2):448-460

  相似文献   

The Bolcana Cu–Au ore deposit (Metaliferi Mountains,Romania): first data on the alteration and related mineralisation     

Viorica Milu  Jacques L Leroy  Patrice Piantone 《Comptes Rendus Geoscience》2003,335(8):671-680

The Bolcana ore deposit (Metaliferi Mountains, western Romania) is a porphyry ore deposit with associated epithermal veins. On the basis of different parageneses, four alteration types were distinguished: potassic, phyllic, argillic and propylitic. The mineralogical and geochemical data and estimated crystallisation temperatures of alteration minerals indicate an evolution of the system from an early period of porphyry type mineralisation (Cu+Au) to a late period of low-sulphidation epithermal mineralisation (Au+base metal). To cite this article: V. Milu et al., C. R. Geoscience 335 (2003).  相似文献   

A New Probabilistic Seismic Hazard Analysis for the Vrancea (Romania) Seismogenic Zone     

Mäntyniemi  P.  Mârza  V.  Kijko  A.  Retief  P. 《Natural Hazards》2003,29(3):371-385

In this paper we apply a probabilistic methodology to map specific seismic hazard induced by the Vrancea Seismogenic Zone, which represents the uttermost earthquake danger to Romania as well as its surroundings. The procedure is especially suitable for the estimation of seismic hazard at an individual site, and seismic hazard maps can be created by applying it repeatedly to grid points covering larger areas. It allows the use of earthquake catalogues with incompletely reported historical and complete instrumental parts. When applying themethodology, special attention was given to the effect of hypocentral depth and the variation of attenuation according to azimuth. Hazard maps specifying a 10% chance of exceedance of the given peak ground acceleration value for an exposure time of 50 years were prepared for three different characteristic depths of earthquakes in the Vrancea area. These maps represent a new realistic contribution to the mitigation of the earthquake risk caused by the Vrancea Seismogenic Zone in terms of: (1) input data (consistent, reliable, and the most complete earthquake catalogue), (2) appropriate and specific attenuation relationships (considering both azimuthal and depth effects); and (3) a new and versatile methodology.  相似文献   

Shoshonitic liquid line of descent from diorite to granite: the Late Precambrian post-collisional Tismana pluton (South Carpathians, Romania)   总被引：6，自引：0，他引：6  

Jean-Clair Duchesne  Tudor Berza  Jean-Paul Li  geois  Jacqueline Vander Auwera 《Lithos》1998,45(1-4):281-303

The post-collision late-kinematic Tismana pluton belongs to the shoshonitic series. It is part of a Late Precambrian basement within the Alpine Danubian nappes of the South Carpathians (Romania). This pluton displays an exceptionally complete range of compositions from ultramafic to felsic rocks (granites). Widespread mingling/mixing relationships at all scales give rise to a variety of facies. A liquid line of descent from the diorites to the granites is reconstructed by considering the variation in major and trace elements (REE, Sr, Rb, Ba, Nb, Zr, Hf, Zn, V, Co, Cr, U, Th, Ga, Pb) from 33 selected samples as well as mineral/melt equilibrium relationships. The first step of fractional crystallization is the separation from a monzodioritic parent magma of a peridotitic cumulate similar to the ultramafic rock found in the massif. A possible contamination by lower crustal mafic component takes place at this stage. The second step marks the appearance of apatite and Fe–Ti oxide minerals as liquidus phases, and the third step, saturation of zircon. Mixing by hybridisation of magmas produced at different stages of the evolution along the liquid line of descent is also operating (endo-hybridisation). As depicted by Nd and Sr isotopes, fractional crystallization was combined to an important early contamination by a mafic lower crust in a deep-seated magma chamber and to a later and mild contamination by a felsic medium crust in an intermediate chamber. The mingling essentially occurred during the final emplacement in the high-level magma chamber. The monzodioritic parent magma, identified by major and trace element modelling, is shown by Sr and Nd isotopes to have its source in the lithospheric mantle or in a juvenile mafic lower crust derived from it. The necessarily recent enrichment in K₂O and associated elements of the lithospheric mantle is likely to be related to the preceding Pan-African subduction period. The partial melting of this newly formed deep source has to be linked to a major change in the thermal state of the plate.  相似文献   

Nature and significance of a Cambro-Ordovician high-K, calc-alkaline sub-volcanic suite: the late- to post-orogenic Motru Dyke Swarm (Southern Carpathians, Romania)     

Olivier Féménias  Tudor Berza  Mihai Tatu  Hervé Diot  Daniel Demaiffe 《International Journal of Earth Sciences》2008,97(3):479-496

The Motru Dyke Swarm intrudes the Precambrian Danubian basement of the Southern Carpathians (Romania). It is a marker of a sub-volcanic event that occurred during the early Palaeozoic (Cambrian to Ordovician). The geographical distribution of dykes on a ∼2,000 km² area is heterogeneous; several areas of high dyke density have been the subject of a detailed petrological and geochemical study. Taken altogether, the 150 samples define a single complete magmatic series, from basaltic andesite to rhyolite. Whole-rock major element variations show a medium- to high-K, calc-alkaline magmatic suite. The compositional variations and the general decrease of trace element contents (both compatible and incompatible, including REEs) from basaltic andesite to rhyolite are consistent with 1) the fractionation of the observed phenocryst assemblages, Ca-amphibole (Ti-pargasite to magnesiohornblende) followed by intermediate plagioclase, clinopyroxene and accessory biotite and quartz and 2) the absence of lower and/or upper crustal contamination. Trace elements diagrams display typical arc patterns (LILE, Pb and LREE enrichment and relative depletion in Nb-Ta, Zr-Hf and Ti). The Th/U, Nb/Ta and Zr/Hf ratios are constant and close to the mantle values throughout the whole series, which argues that the parental magma was generated from a single and homogeneous enriched lithospheric mantle source. The field regional evidence implies that melting occurred during a late- to post-orogenic period of lithospheric extension, and thus took place quite lately after the cessation of Pan-African subduction.  相似文献   

Planning regional development: Promoting small settlements in a trans-frontier situation     

Erika Nagy  David Turnock 《GeoJournal》2000,50(2-3):255-271

Under communism local authorities tended to be largely passive bystanders in a regional development process which emerged through the central planning process through the spatial allocations of investment by government ministries. Attention was given to physical planning, but comparatively little material entered the public domain on location policy and spatial priorities generally, apart from the objective of greater equality between regions and a commitment to backward areas generally. Now that much investment is down to private enterprise and government has become more decentralised and accountable, there is a need for concepts and strategies to coordinate public sector investment and provide guidelines for the evaluation of private development proposals. At the same time, there is an open competition for investment which requires communities to promote themselves in terms of their identity and development potential. This paper offers an overview by taking two countries - Hungary and Romania - where progress can be compared and where the focus can be placed on a common frontier which is diverting attention from conventional regional planning to cross-border cooperation. In both contexts however, attention is given to the ways in which planning can divert investment away from the main centres to the peripheral areas, including action to strengthen the role of small towns and also to improve cohesion among functionally-related groups of settlements and communes. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Probabilistic seismic hazard assessment for Romania and sensitivity analysis: A case of joint consideration of intermediate-depth (Vrancea) and shallow (crustal) seismicity     

Vladimir Yu Sokolov  Friedemann Wenzel  Rakesh Mohindra 《Soil Dynamics and Earthquake Engineering》2009

The earthquake risk on Romania is one of the highest in Europe, and seismic hazard for almost half of the territory of Romania is determined by the Vrancea seismic region, which is situated beneath the southern Carpathian Arc. The region is characterized by a high rate of occurrence of large earthquakes in a narrow focal volume at depth from 70 to 160 km. Besides the Vrancea area, several zones of shallow seismicity located within and outside the Romanian territory are considered as seismically dangerous. We present the results of probabilistic seismic hazard analysis, which implemented the “logic tree” approach, and which considered both the intermediate-depth and the shallow seismicity. Various available models of seismicity and ground-motion attenuation were used as the alternative variants. Seismic hazard in terms of macroseismic intensities, peak ground acceleration, and response spectra was evaluated for various return periods. Sensitivity study was performed to analyze the impact of variation of input parameters on the hazard results. The uncertainty on hazard estimates may be reduced by better understanding of parameters of the Vrancea source zone and the zones of crustal seismicity. Reduction of uncertainty associated with the ground-motion models is also very important issue for Romania.  相似文献   

Heavy metal contamination in the Arieş river catchment, western Romania: Implications for development of the Roşia Montană gold deposit     

Graham Bird  Paul A. Brewer  Mark G. Macklin  Mihaela Serban  Dan Balteanu  Basarab Driga 《Journal of Geochemical Exploration》2005,86(1):26-48

The Abrud–Arieş river system, western Romania, is subject to ongoing mining activity associated with Cu, Pb and Zn ore extraction. The catchment contains what is believed to be Europe's largest unutilized Au deposit at Roşia Montană that is planned to be exploited by open-cast mining techniques. The magnitude and environmental significance of metal (Cd, Cu, Pb, and Zn) concentrations in surface water and river channel sediment have been investigated along a 140 km reach of the Rivers Abrud and Arieş and 9 tributaries affected by mining. The speciation of sediment-bound metals was established using a 4-stage sequential extraction procedure (SEP) that identified four chemical phases: (1) exchangeable, (2) Fe/Mn oxides, (3) organic matter/sulphides and (4) residual. Peak solute and sediment-bound metal concentrations were found to occur in the River Abrud downstream of the EM Bucium mine and in mining-affected tributaries, with up to 71% of sites containing sediment metal concentrations in excess of Dutch intervention values. The River Arieş was found to be much less polluted than the River Abrud, with only Cu showing concentrations above guideline values, as a consequence of porphyry Cu mineralization in the catchment. The magnitude and spatial extent of metal pollution is influenced by local physico-chemical conditions and hydrological linkages between mining and local river systems. Sediment-bound Cd and Zn were found to be predominantly associated with the exchangeable phase of the sediment (9–74% and 6–65%, respectively), whilst Fe/Mn oxides (5–76%) and organic matter/sulphides (1–45%) generally accounted for a majority of Pb and Cu partitioning, respectively. Sites of environmentally significant sediment-metal pollution were identified in the Rivers Abrud and Arieş where exchangeable metal concentrations exceeded Dutch intervention values. The implications of metal contamination in the Arieş river basin to the proposed mining development at Roşia Montana are discussed in relation to other contaminated Romanian catchments and with the EU Water Framework Directive.  相似文献   

Te-Rich argyrodite occurrence in Roşia Montană ore deposit,Apuseni Mountains,Romania     

Laurent Bailly  Călin-Gabriel Tămaş  Adrian Minuţ 《Comptes Rendus Geoscience》2005,337(8):755-762

A new argyrodite occurrence has been discovered in the Ro?ia Montan? ore deposit located in the South Apuseni Mountains, Romania. Argyrodite is associated with common base metal sulfides and sulfosalts (galena, sphalerite, chalcopyrite, tetrahedrite ± alabandite, pyrite, and marcasite), tellurides (hessite, altaite, sylvanite) and rare electrum grains in the Ag-rich Cârnicel vein hosted by an extracraterial phreatomagmatic breccia within the Cârnic massif. SEM and EPMA analyses revealed that this argyrodite is Te-rich and a mean Ag_8.04Ge_0.9Te_2.07S_3.77 formula was calculated. This phase could be the germaniferous equivalent of the previously-described Te-rich canfieldite. To cite this article: L. Bailly et al., C. R. Geoscience 337 (2005).  相似文献   

Intrinsic vulnerability of Coteţul Dobreştilor karst aquifer (Bihor Mountain, Romania)     

Orăşeanu Iancu  Parichi Mihai  Scrădeanu Daniel 《Environmental Geology》2007,51(5):713-718

The evaluation of the vulnerability of the karst aquifer and the source in the Coteţul Dobreştilor system was performed on the basis of geological, hydrogeological and pedological data. The methods proposed in the Final Report of COST Action 620 were used. The available field data resulted in assessing the parameters P, I and in characterizing the saturated aquifer karstic network parameter (K). The soil cover over the carbonate deposits is generally shallow and easily bypassed by the superficial flow, the protection of the karstic aquifer and the source thus being minimal.  相似文献