Ernst Weinschenk (1865–1921) a pioneer of microscopy and petrography in Munich (Southern Germany)

Ernst Weinschenk was an excellent teacher at the High School of Technology from 1897 till his death 1921, and at the university in Munich from 1900. His studies of the mineralogy of meteorites and the contact-metamorphic mineralization in the eastern and western Alps and southern Tyrol made him widely known early-on. He successfully determined many new minerals with the aid of the polarizing microscope and the use of mineral and thin rock sections. He attributed the genesis of the sulfidic ore deposit Silberberg at Bodenmais (northern Bavarian Forest) and the graphite deposits near Passau (Lower Bavaria) to the exhalative output of sulphur and carbon during the granite orogenesis (Weinschenk 1914).     

Colin Patterson (1933–1998): a major vertebrate palaeontologist of this century

Geologie en Mijnbouw -     

Groundwater–wetlands interaction in coastal lagoon of Almería (SE Spain)

Water resources management in coastal wetlands requires the degree of interdependence between groundwater and terrestrial ecosystems to be known. This is especially so in semiarid areas where surface inflows are restricted, marine influence is marked and the evaporation rate is high. Thus, chemistry of surface waters is very variable in the Cerrillos-Punta Entinas wetlands system. Using classical hydrogeochemical tools, the main processes that favor a diversity of water types were described, related to: presence of salt deposits on the lagoon beds, marine origin of the water, and local influence of groundwater. All these factors make it difficult to establish what reference conditions should be used to define “good” water quality of the surface waters—as required by the Water framework directive—and to understand the influence of groundwater on these coastal wetlands. Knowledge about the influence of the different interaction of these factors on the hydrogeochemical dynamics is required for the sustainable management of this protected natural site.     

Structural cutting of a region showing various compound tectonic deformations (example of Bouficha–Grombalia region)

Bouficha–Grombalia region shows complex tectonic deformations and is affected by faults and folds of different geometry. A structural study has allowed to determine that Bouficha–Grombalia region is affected by significant faults of EW, NE-SW and NW-SE directions. These faults divide Bouficha–Grombalia region into several compartments. We distinguish three important structures whose first is in the SW which corresponds to Zaghouan–Bouficha trough. The second structure is situated in the NE, which corresponds to the Grombalia trough. The third structure occupies a central position; it consists in the Bouficha–Grombalia high structure. The last structure is composed by three blocks. Each block is characterised by particular folds geometry. These structures were outlined at least from middle Miocene, and they have undergone the effect of subsequent compressive tectonic events which have led to folds building above or counter the pre-existing NE-SW faults.     

Thermodynamic description of equilibria in mixed fluids (H2O-non-polar gas) over a wide range of temperature (25–700°C) and pressure (1–5000 bars)

A new method for computing complicated equilibria in hydrothermal mixed fluids, H₂O-non-polar gas, is proposed. The computation algorithm is based on the electrostatic approach for the interaction between aqueous species and H₂O. The approach uses the SUPCRT92 database and the HKF format and may be considered as an application of the revised HKF model for mixed H₂O-non-polar gas fluids. Thermodynamic properties of dissolved gases at high temperatures and pressures are calculated using the Redlich-Kwong approach. Dielectric permittivity of the mixed solvent is estimated by the modified Kirkwood equation.The proposed approach is validated using available experimental data on the dissociation constants of H₂O and NaCl and the solubility of both covalent and ion crystals (SiO₂, AgCl, Ag₂SO₄, Ca(OH)₂, CaCO₃) in H₂O-non-polar component (dioxane, Ar, CO₂) mixtures. Predicted and experimental data are in close agreement over a wide range of P-T-x_gas conditions (up to 500°C, 4 kbar and 0.25–0.3 mole fraction of non-polar gas). It is also shown how the computation method can be applied to estimate the Born parameters of aqueous species.The proposed approach enables not only examination of isolated reactions, but the study of equilibria of whole systems. Thus, it allows modelling of mixed natural fluids.     

Activity rating of Pliocene–Quaternary faults: a formalized approach (example of the Baikal rift system)

It is suggested to estimate the Pliocene–Quaternary fault activity in a formalized way from synthesis of different data. The respective database consists of two main sections: (i) general information and basic fault parameters and (ii) geomorphic, structural, paleoseismic, seismological, geophysical, geodetic, engineering-geological, hydrological, and meteorological data. The fault characteristics are scored according to their significance, and the cumulative score measures the fault activity. With this approach, the faults in the Barguzin and Tunka rift basins and in the northeastern flank of the Baikal rift system have been divided into five activity classes (low, medium, relatively high, high, and very high activity) and mapped correspondingly. It has been recommended that the concept of an hazardous fault, as updated with regard to the activity rating, refers to faults of relatively high, high, and very high activity. Thus identified hazardous faults within the study area are quite few (4–8%), though this percent may increase slightly as more input data become available. The underestimation cannot be dramatic because all known seismological and structural characteristics of faults essential for the activity rating have been already taken into account. The new approach may be useful in seismic risk assessment and in choice of sites for instrumental monitoring of seismicity.     

The nationalization of electoral change in a geographical perspective: the case of Italy (2006–2008)

This paper assesses the nationalization of electoral change in a setting of major changes at the party level. After discussing the theoretical difference between the configuration of the electorate and its movement, the Italian case is examined. In order to check whether strategic voting dynamics took place between the 2006 and 2008 Italian Parliamentary elections, the swing voters’ estimates are obtained. After having shown that the Italian electorate behaved strategically, we investigated whether the swing had a national or a territorial pattern. The findings show that the switching occurred in Italy between the 2006 and the 2008 elections can be considered national.     

Mobility of rare earth elements in the system soils–plants–groundwaters: a case study of an arid area (Oman)

Groundwater samples from six wells and various species of plants from soils developed on ophiolites were collected from an arid area (AlKhod area, Oman) and analyzed for trace elements including rare earth elements (REEs). The distribution patterns of REEs in plants indicated an enrichment in middle REEs (MREEs?=?Sm to Dy) and heavy REEs (HREEs?=?Ho to Lu), when they are normalized to the REE composition of the Post Archean Australian Shale (PAAS), with a significant negative anomaly in Ce and a positive anomaly in Eu. Compared to Oman ophiolites, the REEs in different species of plants are depleted in Ce and enriched in MREEs and slightly enriched in light REE (LREE?=?from La to Nd). Relative to PAAS, the distribution of REEs in groundwaters revealed similar patterns to the REE distribution in plants. The distribution patterns of REEs in plants relative to those in waters are nearly flat. These patterns suggest that the transfer of REEs from soil solutions to the groundwaters in Oman occurs without any significant fractionation.     

Garnet–orthopyroxene (GOPX) geothermometer: a comparative study

The garnet–orthopyroxene pairs are commonly found in the assemblages of basic granulites/charnockite and hence are suitable for estimating equilibrium temperature of these metamorphic rocks. At present, there are many calibrations of garnet–orthopyroxene thermometer that may confuse geologists in choosing a reliable thermometer. To test the accuracy of the garnet–orthopyroxene thermometers, we have applied 14 models formulated by a number of workers since 1980 to date. We have collated 51 samples from the literature all over the world, which has been processed through the “Gt-Opx.EXE” software. Based on the present study, we have identified a set of the best among all the 14 models which were considered under this comparative study. We have concluded that the five garnet–orthopyroxene (Gt-Opx) thermometers are the most valid and reliable of this kind of thermometer: Aranovich and Berman (Am Mineral 82:345–353, 1997), Raith et al. (Earth Sci 73:211–244, 1983), Harley (Contrib Mineral Petrol 86:359–373, 1984), Nimis and Grütter (Contrib Mineral Petrol 159:411–427, 2010), and Sen and Bhattacharya (Contrib Mineral Petrol 88:64–71, 1984).     

Geochronology of a composite granitoid pluton: a high-precision ID-TIMS U–Pb zircon study of the Variscan Karkonosze Granite (SW Poland)

Resolving time differences between successive magmatic pulses in composite granitoid plutons is often a difficult task. High-precision CA-ID-TIMS zircon ages obtained from such a pluton, the Variscan Karkonosze Granite (NE part of the Bohemian Massif), provide evidence that the crystallization of the two main granite facies, porphyritic and equigranular, happened between 312.5 ± 0.3 and 312.2 ± 0.3 Ma, thus unresolvable at the 0.08–0.1 % precision level of a single ²⁰⁶Pb/²³⁸U age. This finding is at odds with most other previous dating attempts and asks for a re-evaluation of the previous scattered geochronological data. The main reasons for the scatter of the earlier dates obtained by various techniques can include analytical causes, the presence of older inheritance and disturbance of the U–Pb isotopic system, due to zircon metamictization (enhanced by high-U content in zircon) or late- and post-magmatic alteration.     

Rock pulverization and localization of a strike-slip fault zone in dolomite rocks (Salzach–Ennstal–Mariazell–Puchberg fault,Austria)

Detailed investigations of dolomite fault rocks, formed at shallow crustal depths along the Salzach–Ennstal–Mariazell–Puchberg (SEMP) fault system in the Northern Calcareous Alps, revealed new insights into cataclasite formation. The examined Miocene, sinistral strike-slip faults reveal grain size reduction of dolomite host rocks by tensile microfracturing at a large range of scales, producing rock fragments of centimetre to micrometre sizes. In situ fracturing leads to grain size reduction down to grain sizes <25 μm, producing mosaic breccias and fault rocks which have previously been described as “initial/embryonic” and “intermediate” cataclasites. At all scales, grain fragments display little to no rotation and no or minor evidence of shear deformation. The observed microstructures are similar to those previously described in studies on pulverized rocks. Microstructural investigations of cataclasites and mosaic breccias revealed aggregations of small dolomite grains (<50 μm) that accumulated on top of large fragments or as infillings of V-shaped voids between larger grains and show constant polarity throughout the investigated samples. Fabrics indicate deposition in formerly open pore space and subsequent polyphase cementation. The newly described tectonic geopetal fabrics (geopetal-particle-aggregates, GPA) prove that these faults temporarily passed through a stage of extremely high porosity/permeability prior to partial cementation.     

Long-term variability of a complete sample of flat-spectrum radio sources at declinations of 4°–6° (B1950)

We present the results of twenty-year observations of a complete sample of 68 flat-spectrum radio sources with flux densities S _{3.9 GHz} > 200 mJy carried out at centimeter wavelengths with the RATAN-600 radio telescope. Since 1995, we have observed simultaneously at six frequencies between 0.97 and 21.7 GHz. Of the 56 sources identified with optical objects, 41 are quasars with redshifts between 0.293 and 3.263. Based on our analysis of the spectral shapes, we divide the sources into four classes. Changes of spectral class for individual sources are fairly rare. Based on the light curves and spectra, in most cases, a flare’s evolution is in accordance with a model in which the variations result from the evolution of a shock in the radio jet. The main result of our study is that there is no redshift dependence for the true linear sizes of the radiating regions, the variability indices derived for all 20 years of data or for individual flares, or the peak frequencies of the spectra of the compact radio emission. We suggest that this testifies to an absence of cosmological evolution of the sample quasars, at least to z ≈ 3.     

Manifestation of nitrogen interstitials in synthetic diamonds obtained using a temperature gradient technique (Fe–Ni–C system)

The IR-peak 1450 cm^–1 (H1a-center) associated with nitrogen interstitials have been studied in nitrogen-bearing diamonds synthesized at high P-T parameters in the Fe–Ni–C system. FTIR study shows that manifestation of this nitrogen form is restricted to the regions of active transformation of C-defects into A-defects, which confirms the connection of its formation with C => A aggregation process. An examination of the dependence of the 1450 cm^–1 peak on the degree of nitrogen aggregation indicates that H1a-centers are not only formed during C/A aggregation but also disappear simultaneously with the end of C => A transformation. Established facts suggest direct involving of nitrogen as interstitials in the C => A aggregation and serve as strong experimental argument in support of the “interstitial” mechanism of nitrogen migration during aggregation in diamonds containing transition metals.     

Identification of Self-Potential Anomalies of a Diffusion–Absorption Origin

Diffusion and adsorption (DA) potentials are frequently the sources of self-potential (SP) anomalies, but they do not arouse practical interest in contrast to anomalies of oxidation–reduction and filtration origins. DA anomalies are common and geophysicists sometimes mistakenly consider DA anomalies as examples of filtration anomalies. Identification of DA anomalies is based on correlation of SP and apparent resistivity values along the same profiles. During the student geophysical training workshop for students of the Moscow State University (Aleksandrovka village, Kaluga Region) we obtained profiles with SP and resistivity anomalies with good correlation between them. This makes it possible to consider such SP anomalies as a result of DA processes.     

Hydrologic characteristics of floods in Ganges–Brahmaputra–Meghna (GBM) delta

In the middle of 2007, a severe flood affected the People’s Republic of Bangladesh. This is a natural disaster that takes people’s lives, destroys livestock, infrastructures and communication systems and, damages crops and fish ponds. Despite many adverse impacts, the flood situation is an accepted phenomenon to the citizens of Bangladesh, due to the immense increase of soil fertility due to the flood, plus, the recharge of aquifer, ecosystem and fish. The flood of 2007 was the 5th major flood of the last 20 years when more than thirty-five percent of the area of the country was inundated with flood water. As in the past, the flood of 2007 had its own significance. The geography of the country contains a floodplain delta of three major river basins: the Ganges, the Brahmaputra and the Meghna (GBM). The mean monthly rainfall plot from the TRMM satellite data has shown that for both the Meghna and Brahmaputra basins, the rainfall was higher during July 2007 than any other months of the last 2 years. This excess rainfall had accumulated in the Brahmaputra and Meghna rivers and carried downstream to Bangladesh. This was the main cause of the flooding in 2007. The first crossing above the danger level of the river waters was observed at Durgapur station of the Someswari and at Sunamganj station of the Surma on the nineteenth of July, 2007 inside Bangladesh. In terms of magnitude of the peak and duration of the flood, the Brahmaputra was higher in 2007 than during 2004. However, the Ganges river water level never crossed the danger level during flood of 2007. The Meghna was lower during the flood peak for the duration of the flood in 2007. The year–to-year variability in both the magnitude and duration of the flood suggests changes in rainfall and landuse pattern of the catchment.     

Reconstruction of the Neoproterozoic–Cambrian Orogenesis in Princess Elisabeth Land (East Antarctica) from a Study of Granitic Rocks

Abundant Cambrian granitic rocks in Princess Elizabeth Land and adjacent regions of Antarctica occupy various positions (from syn- to postkinematic) in the structure of the crust. Their mineral and isotopic composition reflects both the character and age of the parental substrate and geodynamic formation conditions of the region. The study of Cambrian processes is important for this region, because almost all known models of the formation of the Gondwana supercontinent suggest the Neoproterozoic–Cambrian amalgamation of two or three continental blocks, parts of which can be distinguished in this sector. The paper presents geological data on granitic rocks, as well as their mineral and Nd isotopic composition. Field observations and analytical data indicate a different structure and petrographic composition of Cambrian granitic rocks in Princess Elizabeth Land, which are related to their different formation conditions. Synkinematic biotite or garnet–biotite peraluminous S-type granites mostly occur in the eastern Princess Elizabeth Land. Mostly late and postkinematic biotite and amphibole–biotite (±orthopyroxene) granites or granodiorites are typical of its western part. Their compositions are similar to that of A-type granites. In comparison with coeval granites in adjacent areas, the character of Cambrian granites in Princess Elizabeth Land substantiates the presence of structural zones identified from geological data and indicates the presence of a Cambrian orogen probably with a collisional nature, as well as the location of its hinterland in intracontinental Antarctica.     

Glacial–interglacial records of the reflectance of sediments from the Norwegian–Greenland–Iceland Sea (Nordic seas)

 The reflectance of sediments (gray level) were measured on 11 sediment cores from the Norwegian–Greenland–Iceland Sea (Nordic seas). The analyzed time interval covers the past five glacial–interglacial cycles. Although the results demonstrate that the gray-level method has a potential for stratigraphic purposes, it is indicated that gray-level changes in the Nordic seas are not necessarily driven by variations in the content of biogenic calcite. A detailed comparison of gray-level values with contents of total CaCO₃ (carbonate) and total organic carbon (TOC) reveals no overall causal link between these proxies. However, specific glacial core sections with layers containing organic-rich sediment clasts as a consequence of iceberg-rafting seem to correlate well with law gray-level values. Of those cores which show relatively high and comparable carbonate values in the last three main interglacial intervals (stages 11, 5.5, and 1), stage 11 is always marked by the highest gray-level values. A close inspection of the surface structure of the foraminiferal tests as well as the conduction of reflectance measurements on these tests leads to the conclusion that enhanced carbonate corrosion occurred during stage 11. The test corrosion not only affected the reflectance of the tests by making them appear whiter, it also seems responsible for the comparatively high gray-level values of the total sediment in stage 11. In contrast, the relatively low gray-level values found in stages 5.5, and 1 are not associated with enhanced test corrosion. This observation implies that variable degrees of carbonate corrosion can have a profound effect on total sediment reflectance. Received: 6 September 1998 / Accepted: 4 April 1999     

U–Pb Isotope Age of Zircon (LA–ICP–MS Method) from Magmatic Rocks and Some Aspects of the Genesis of the Tyrnyauz Mo–W Deposit (North Caucasus)

Geology of Ore Deposits - The authors' determinations of the U–Pb isotopic age of zircon (LA–ICP–MS method) in the main types of igneous rocks emphasize the presence of both...     

Percival Allen FRS (1917–2008): a personal tribute

This paper summarises the author's research association with Percival (‘Perce’) Allen FRS (1917–2008), whose wide-ranging and seminal contributions to Wealden (non-marine Lower Cretaceous) sedimentological and palaeoenvironmental interpretation spanned seven decades. The Geological Conservation Review (GCR) Special Issue on the Wealden was initiated as a collaborative research programme initiated during the late 1990s. Stemming from this, the GCR accounts are seen very much as the summation of Perce Allen's lifelong Wealden studies, as demonstrated by GCR sites throughout southern England.