Geokinematics of Central Europe: New insights from the CERGOP-2/Environment Project

The Central European Geodynamics Project CERGOP-2, funded by the European Union from 2003 to 2006 under the 5th Framework Programme, benefited from repeated measurements of the coordinates of epoch and permanent GPS stations of the Central European GPS Reference Network (CEGRN), starting in 1994. Here we report on the results of the systematic processing of available data up to 2005. The analysis has yielded velocities for some 60 sites, covering a variety of Central European tectonic provinces, from the Adria Indenter to the Tauern Window, the Dinarides, the Pannonian Basin, the Vrancea Seismic Zone and the Carpathian Mountains. The estimated velocities define kinematical patterns which outline, with varying spatial resolution depending on the station density and history, the present-day surface kinematics in Central Europe. Horizontal velocities are analyzed after removal from the ITRF2000 estimated velocities of a rigid rotation accounting for the mean motion of Europe: a 2.3 mm/year north–south oriented convergence rate between Adria and the Southern Alps that can be considered to be the present-day velocity of the Adria Indenter relative to the European Foreland. An eastward extrusion zone initiates at the Tauern Window. The lateral eastward flow towards the Pannonian Basin exhibits a gentle gradient from 1 to 1.5 mm/year immediately east of the Tauern Window to zero in the Pannonian Basin. This kinematic continuity implies that the Pannonian plate fragment recently suggested by seismic data does not require a specific Eulerian pole. On the southeastern boundary of the Adria microplate, we report a velocity drop from 4 to 4.5 mm/year motion near Matera to 1 mm/year north of the Dinarides, in the southwestern part of the Pannonian Basin. A positive velocity gradient as one moves south from West Ukraine across Rumania and Bulgaria is estimated to be 2 mm/year on a scale of 600–800 km, as if the crust were dragged by the counterclockwise rotation along the North Anatolian Fault Zone. This regime apparently does not interfere with the Vrancea Seismic Zone: earthquakes there are sufficiently deep (>100 km) that the brittle deformation at depth can be considered as decoupled from the creep at the surface. We conclude that models of the Quaternary tectonics of Central and Eastern Europe should not neglect the long wavelength, nearly aseismic deformation affecting the upper crust in the Romanian and Bulgarian regions.     

Surface kinematics in the Alpine–Carpathian–Dinaric and Balkan region inferred from a new multi-network GPS combination solution

The understanding of the intraplate tectonics of Central Europe requires a detailed picture of how stress is transferred from the interaction of the Eurasian, Nubian and Anatolian plates to the Alpine, Carpathian, Pannonian and Dinaric regions. Recent strain distribution is controlled by the Adria horizontal push, by the Vrancea vertical slab pull and associated horizontal displacements, and by the Aegean/Anatolia extension and slab-roll back. We present a horizontal velocity field for the Alpine-Carpathian-Pannonic-Dinaric and Balkan regions resulting from a new combination of seven different GPS networks formed from permanent and campaign stations. Dedicated velocity profiles in two specific regions are studied in detail. One is the Alpine Pannonian region, with a detailed picture of the NS indentation of the Adria microplate into the Southern Alps, in NE Italy, the deformation in the Tauern Window and the eastwards kinematics of a Pannonian plate fragment. The second study region includes Transylvania, the Southern Carpathians up to the Aegean sea and Albania, where a major right lateral shear deformation exists as a consequence of the NE convergence of the Apulia platform towards the Dinarids, and the SSW motion of Macedonia, Western Bulgaria and Rumania, related to the Hellenic arc dynamics in the Eastern Mediterranean. The profiles in the Alpine–Pannonian area indicate that a velocity drop of 2.5 +/− 0.4 mm/yr associated with the Adria indentation concentrates on a segment of some 50 km south of the Periadriatic fault. The deformation becomes extensional by a similar amount just north of the Periadriatic fault, in the Tauern Window, where the updoming of the Tauern Window implies vertical motion which could well be associated with surface extension. In the EW profile, we observe a sudden velocity change of 1.5 +/− 0.2 mm/yr in 20 km, corresponding to the right lateral Lavant fault, which seems to mark the border between dominant indentation kinematics to the West and dominant extrusion kinematics to the East.Three profiles are considered in Southern and Eastern Europe: one across the lower Adriatic sea from Apulia in Italy to the southern Dinarides, which enables it to constrain the velocity drop associated with the subduction of the Adria microplate into the Dinarides to 3.2 +/− 0.5 mm/yr in 140 km. The second profile is longitudinal and constrains the velocity inversion of 7.4 +/− 1.0 mm/yr in 350 km associated with right lateral shear faults in Albania. The third profile crosses the Transylvania region with a shortening of 2.3 +/− 1.0 mm/yr in 220 km, and the Wallachian–Moesian region up to the Chalcidic peninsula in N Greece. This lower part of the profile implies an extensional stretch of the upper crust of 3.2 +/− 0.9 mm/yr in 440 km, culminating in the Hellenic arc. Strain rate maps are presented in this regional scale, showing the excellent agreement between fault plane solutions of crustal earthquakes and the eigenvectors of the GPS derived two dimensional strain rate tensor.Three profiles are considered in the Balkan and SE Carpathians: one across the lower Adriatic sea from Apulia in Italy to the southern Dinarides, which enables to constrain the velocity drop associated to the subduction of the Adria microplate into the Dinarides to 3.2 +/− 0.5 mm/yr in 140 km. The second profile is longitudinal and constrains the velocity inversion of 7.4 +/− 1.0 mm/yr in 350 km associated to right lateral shear faults in Macedonia, a highly seismic region. The third profile crosses the Transylvania with a shortening2.3 +/− 1.0 mm/yr in 220 km, and the Wallachian–Moesian region up to the Chalcidic peninsula in N Greece. This lower part of the profile implies an extensional stretch of the upper crust of 3.2 +/− 0.9 mm/yr in 440 km, culminating in the Hellenic arc.     

A novel nuclear forensic tool involving deposit type normalized rare earth element signatures

Identifying the provenance of uranium‐rich materials is a critical objective of nuclear forensic analysis. Rare earth element (REE) distributions within uranium ores are well‐established forensic indicators, but quantifying and correlating trace element signatures for U ores to known deposits has thus far involved intricate statistical analyses. This study reports average chondrite normalized (CN)‐REE signatures for important U deposit types worldwide, which are then employed to evaluate U ore paragenesis using a simple linear regression analysis. This technique provides a straightforward method that can aid in determining the deposit type of U ores based on their REE abundances, and combined with other forensic indicators (e.g. radiogenic isotope signatures) can provide essential provenance information for nuclear materials.     

On the regional distribution of mitigation costs in a global cap-and-trade regime

This paper analyzes the regional distribution of climate change mitigation costs in a global cap-and-trade regime. Four stylized burden-sharing rules are considered, ranging from GDP-based permit allocations to schemes that foresee a long-term convergence of per-capita emission permits. The comparison of results from three structurally different hybrid, integrated energy-economy models allows us to derive robust insights as well as identify sources of uncertainty with respect to the regional distribution of the costs of climate change mitigation. We find that regional costs of climate change mitigation may deviate substantially from the global mean. For all models, the mitigation cost average of the four scenarios is higher for China than for the other macro-regions considered. Furthermore, China suffers above-world-average mitigation costs for most burden-sharing rules in the long-term. A decomposition of mitigation costs into (a) primary (domestic) abatement costs and (b) permit trade effects, reveals that the large uncertainty about the future development of carbon prices results in substantial uncertainties about the financial transfers associated with carbon trade for a given allocation scheme. This variation also implies large uncertainty about the regional distribution of climate policy costs.     

Implications of weak near-term climate policies on long-term mitigation pathways

While the international community has agreed on the long-term target of limiting global warming to no more than 2 °C above pre-industrial levels, only a few concrete climate policies and measures to reduce greenhouse gas (GHG) emissions have been implemented. We use a set of three global integrated assessment models to analyze the implications of current climate policies on long-term mitigation targets. We define a weak-policy baseline scenario, which extrapolates the current policy environment by assuming that the global climate regime remains fragmented and that emission reduction efforts remain unambitious in most of the world’s regions. These scenarios clearly fall short of limiting warming to 2 °C. We investigate the cost and achievability of the stabilization of atmospheric GHG concentrations at 450 ppm CO₂e by 2100, if countries follow the weak policy pathway until 2020 or 2030 before pursuing the long-term mitigation target with global cooperative action. We find that after a deferral of ambitious action the 450 ppm CO₂e is only achievable with a radical up-scaling of efforts after target adoption. This has severe effects on transformation pathways and exacerbates the challenges of climate stabilization, in particular for a delay of cooperative action until 2030. Specifically, reaching the target with weak near-term action implies (a) faster and more aggressive transformations of energy systems in the medium term, (b) more stranded investments in fossil-based capacities, (c) higher long-term mitigation costs and carbon prices and (d) stronger transitional economic impacts, rendering the political feasibility of such pathways questionable.     

Global energy security under different climate policies,GDP growth rates and fossil resource availabilities

Energy security is one of the main drivers of energy policies. Understanding energy security implications of long-term scenarios is crucial for informed policy making, especially with respect to transformations of energy systems required to stabilize climate change. This paper evaluates energy security under several global energy scenarios, modeled in the REMIND and WITCH integrated assessment models. The paper examines the effects of long-term climate policies on energy security under different assumptions about GDP growth and fossil fuel availability. It uses a systematic energy security assessment framework and a set of global and regional indicators for risks associated with energy trade and resilience associated with diversity of energy options. The analysis shows that climate policies significantly reduce the risks and increase the resilience of energy systems in the first half of the century. Climate policies also make energy supply, energy mix, and energy trade less dependent upon assumptions of fossil resource availability and GDP growth, and thus more predictable than in the baseline scenarios.     

Combined regional geoid determination for the ERS-1 radar altimeter calibration

Summary A local model of the geoid in NE Italy and its section along the Venice ground track of the ERS-1 satellite of the European Space Agency is presented. The observational data consist of geoid undulations determined with a network of 25 stations of known orthometric (by spirit leveling) and ellipsoidal (by GPS differential survey) and of 13 deflections of the vertical measured at sites of the network for which, besides the ellipsoidal (WGS84) coordinates, also astronomic coordinates were known. The network covers an area of 1×1 degrees and is tied to a vertical and horizontal datum: one vertex of the network is the tide gauge of Punta Salute, in Venice, providing a tie to a mean sea level; a second vertex is the site for mobile laser systems at Monte Venda, on the Euganei Hills, for which geocentric coordinates resulted from the analysis of several LAGEOS passes.The interpolation algorithm used to map sparse and heterogeneous data to a regular grid of geoid undulations is based on least squares collocation and the autocorrelation function of the geoid undulations is modeled by a third order Markov process on flat earth. The algorithm has been applied to the observed undulations and deflections of the vertical after subtraction of the corresponding predictions made on the basis of the OSU91A global geoid model of the Ohio State University, complete to degree and order 360. The locally improved geoid results by adding back, at the nodes of a regular grid, the predictions of the global field to the least squares interpolated values. Comparison of the model values with the raw data at the observing stations indicates that the mean discrepancy is virtually zero with a root mean square dispersion of 8 cm, assuming that the ellipsoidal heights and vertical deflections data are affected by a random error of 3 cm and 0.5 respectively. The corrections resulting from the local data and added to the background 360×360 global model are described by a smooth surface with excursions from the reference surface not larger than ±30 cm.     

Downstream lightening and upward heavying: Experiments with sediments differing in density

Sorting and selective transport of particles by material density is important for understanding a wide range of processes, including the formation of mineral placers, deposition of mine tailings and routing of tracers and contaminants. This article describes an experimental study of the transport of mixtures of particles of differing density in a sediment‐feed flume. During the runs, a downstream prograding wedge‐shaped deposit was formed. Results show two sorting processes: (i) longitudinal sorting characterized by preferential deposition of heavy particles in the upstream part of the deposit – downstream lightening; and (ii) vertical sorting with less dense particles preferentially deposited in the lowermost portion of the migrating front – upward heavying. Downstream lightening is the analogue of the well‐known downstream fining observed in the more studied case of mixtures of heterogeneous size with the same density. In both cases, the lighter particles are carried further downstream than the heavier particles. Upward heavying is unexpected when compared with deposits of heterogeneous size and same‐density particles, where the heaviest (i.e. coarsest) particles are deposited in the lowermost part of the front. The physical mechanism underlying this upward heavying might be related to the physics of gravity‐driven granular flows; the front of the deposit acts like a dense granular flow down an inclined plane. In this case, the denser particles settle away from the free surface and at the top of the heap, while the lighter particles flow to the bottom. As the front of the deposit advances, this progressively gives rise to an upward heavying pattern. The application of classical surface‐based fractional bedload transport models suggests that equal mobility is not approached in the case of mixtures of particles with uniform size and different densities. This study hypothesizes that other mechanics related to the physics of the segregation processes in these systems contribute to these results.     

A detailed mineralogical,petrographic, and geochemical study of the highly reduced chondrite,Acfer 370

Among the many ungrouped meteorites, Acfer 370, NWA 7135, and El Médano 301—probably along with the chondritic inclusion in Cumberland Falls and ALHA 78113—represent a homogeneous grouplet of strongly reduced forsterite‐rich chondrites characterized by common textural, chemical, mineralogical, and isotopic features. All of these meteorites are much more reduced than OCs, with a low iron content in olivine and low‐Ca pyroxene. In particular, Acfer 370 is a type 4 chondrite that has olivine and low‐Ca pyroxene compositional ranges of Fa 5.2–5.8 and Fs 9.4–33.4, respectively. The dominant phase is low‐Ca pyroxene (36.3 vol%), followed by Fe‐Ni metal (16.3 vol%) and olivine (15.5 vol%); nevertheless, considering the Fe‐oxyhydroxide (due to terrestrial weathering), the original metal content was around 29.6 vol%. Finally, the mean oxygen isotopic composition Δ¹⁷O = +0.68‰ along with the occurrence of a silica phase, troilite, Ni‐rich phosphides, chromite, and oldhamite confirms that these ungrouped meteorites have been affected by strong reduction and are different from any other group recognized so far.     

Petrology and oxygen isotopic compositions of calcium‐aluminum‐rich inclusions in primitive CO3.0‐3.1 chondrites

The petrologic and oxygen isotopic characteristics of calcium‐aluminum‐rich inclusions (CAIs) in CO chondrites were further constrained by studying CAIs from six primitive CO3.0‐3.1 chondrites, including two Antarctic meteorites (DOM 08006 and MIL 090010), three hot desert meteorites (NWA 10493, NWA 10498, and NWA 7892), and the Colony meteorite. The CAIs can be divided into hibonite‐bearing inclusions (spinel‐hibonite spherules, monomineralic grains, hibonite‐pyroxene microspherules, and irregular/nodular objects), grossite‐bearing inclusions (monomineralic grains, grossite‐melilite microspherules, and irregular/nodular objects), melilite‐rich inclusions (fluffy Type A, compact type A, monomineralic grains, and igneous fragments), spinel‐pyroxene inclusions (fluffy objects resembling fine‐grained spinel‐rich inclusions in CV chondrites and nodular/banded objects resembling those in CM chondrites), and pyroxene‐anorthite inclusions. They are typically small (98.4 ± 54.4 µm, 1SD) and comprise 1.54 ± 0.43 (1SD) area% of the host chondrites. Melilite in the hot desert and Colony meteorites was extensively replaced by a hydrated Ca‐Al‐silicate during terrestrial weathering and converted melilite‐rich inclusions into spinel‐pyroxene inclusions. The CAI populations of the weathered COs are very similar to those in CM chondrites, suggesting that complete replacement of melilite by terrestrial weathering, and possibly parent body aqueous alteration, would make the CO CAIs CM‐like, supporting the hypothesis that CO and CM chondrites derive from similar nebular materials. Within the CO3.0‐3.1 chondrites, asteroidal alteration significantly resets oxygen isotopic compositions of CAIs in CO3.1 chondrites (?¹⁷O: ?25 to ?2‰) but left those in CO3.0‐3.05 chondrites mostly unchanged (?¹⁷O: ?25 to ?20‰), further supporting the model whereby thermal metamorphism became evident in CO chondrites of petrologic type ≥3.1. The resistance of CAI minerals to oxygen isotope exchange during thermal metamorphism follows in the order: melilite + grossite < hibonite + anorthite < spinel + diopside + forsterite. Meanwhile, terrestrial weathering destroys melilite without changing the chemical and isotopic compositions of melilite and other CAI minerals.