Mesoproterozoic (1.47–1.44 Ga) orogenic magmatism in Fennoscandia; Baddeleyite U–Pb dating of a suite of massif-type anorthosite in S. Sweden

The Jönköping Anorthositic Suite (JAS) in S. Sweden has characteristics typical for (Proterozoic) massif-type anorthosites. The interstitial liquid of these plagioclase-porphyritic rocks solidified at 1,455 ± 6 Ma, as determined by U–Pb isotope analysis of baddeleyite. The JAS developed during a regional 1.47–1.44 event in Fennoscandia that generated widespread mafic magmatism (basalts, and diabase dykes and sills) in the north and emplacement of felsic plutons in the south. The event of 1.47–1.44 Ga magmatism in Fennoscandia largely coincides in age with dynamic high-grade metamorphism in SW Sweden and was probably related to convergent active-margin processes during the Danopolonian orogeny.     

The oxygen isotopic composition as an indicator of the genesis of “Basaltic” corundum

This paper reports an oxygen isotopic study of corundums and associated minerals from the Yogo lamprophyres (Montana, US), plagioclase-corundum inclusions in alkali basalt (Tunkin depression, Russia), and from modern alluvium of Podgelbanochnyi alkaline basaltic volcano (Primorye, Russia). It is shown that all sapphires genetically related to mafic magmatic rocks have a similar oxygen isotopic composition (the variations of δ¹⁸O are within 2.5‰) with most values plotting between +4.5 and +7.0‰ SMOW. The oxygen isotopic ratios in the associated minerals (olivines, pyroxenes, mica, and others) and host rocks are plotted in the same interval. This indicates that the sapphire crystallized during evolution of the parental mafic magma. However, there are xenogenic corundums, which were only transported by basaltic magma to the Earth’s surface. They have a sharply distinct oxygen isotopic composition, which suggests their disequilibrium with the host lavas, and, correspondingly, a different genetic nature.     

Depths of the Sea of Okhotsk sedimentary basin in the Cenozoic

The biofacies analysis of benthic foraminifers in sediments of the Sea of Okhotsk paleobasin revealed the presence of typical abyssal species in their Oligocene-Miocene assemblages that are missing in the Pliocene and Pleistocene section. The development of the abyssal fauna in the Sea of Okhotsk was determined by its relatively large depths (>2000 m) and intense water exchange with the Pacific Ocean. The Sakhalin folding phase at the Neogene-Quaternary transition resulted in the uplifting of the Japan-Kurile cordillera and separation of deep basins of the Japan and Okhotsk seas from the ocean, which was responsible for the formation of unfavorable conditions for migration and existence of the Pacific abyssal fauna. The taxonomic similarity and general tendencies in the development of the Neogene benthic foraminifers common for the Japan and Okhotsk seas imply the lack of narrow and shallow thresholds between these basins similar to the present-day Nevel’skoi, La Pérouse, and Sangar straits. Such bottom topography stimulated the intense northward water flow, which determined the similarity between the benthic foraminiferal assemblages of the Japanese and Okhotsk paleobasins.     

Geochemistry and potential use of groundwater in the Rocca Busambra area (Sicily, Italy)

In the Rocca Busambra area (mid-west Sicily, Italy), from November 1999 to July 2002, 23 water points including wells and springs were sampled and studied for their chemical and isotopic compositions. Two rain gauges were also installed at different altitudes, and rainwater was collected monthly to determine the isotopic composition. The obtained results revealed the Rocca Busambra carbonate complex as being the main recharge area on account of its high permeability value. From a chemical view point, two main groups of water can be distinguished: calcium–magnesium–bicarbonate-type and calcium–magnesium–chloride–sulphate-type waters. The first group reflects the dissolution of the carbonate rocks; the second group probably originates from circulation within flyschoid sediments. Three water wells differ from the other samples due to their relatively high Na and K content, which probably is to be referred to a marked interaction with the “Calcareniti di Corleone” formation, which is rich in glauconite [(K, Na)(Fe³⁺, Al, Mg)₂(Si, Al)₄O₁₀(OH)₂]. In accordance with WHO guidelines for drinking water (2004), almost all the samples collected can be considered drinkable, with the exception of four of them, whose NO₃ ⁻, F⁻ and Na⁺ contents exceed the limits. On the contrary, the sampled groundwater studied is basically suitable for irrigation.     

Crustal seismic velocity in the Marche region (Central Italy): computation of a minimum 1-D model with seismic station corrections

A 1-D velocity model for the Marche region (Central Italy) was computed by inverting P- and S-wave arrival times of local earthquakes. A total of 160 seismic events with a minimum of ten observations, a travel time residual ≤0.8 s and an azimuthal gap lower than 180° have been selected. This “minimum 1-D velocity model” is complemented by station corrections, which can be used to take into account possible near-surface velocity heterogeneities beneath each station. Using this new P-wave velocity model and the program HYPOELLIPSE (Lahr 1999), the selected local events were relocated. Earthquake locations in this study are of higher quality with respect to the original ones. The obtained minimum 1-D velocity model can be used to improve the routine earthquake locations and represents a further step towards more detailed seismotectonic studies of the area.     

Different magneto-rotational supernovae

We present the results of two-dimensional calculations of a magneto-rotational (MR) supernova explosion with a collapsing core for various core masses, rotational angular momenta, and magnetic-field configurations. It is shown that the MR mechanism produces an explosion energy that corresponds to observed values. The form of the explosion depends substantially on the initial configuration of the magnetic field. MR instability develops during the evolution of the magnetic field in an MR supernova explosion, resulting in an exponential increase of all components of the magnetic field, thereby substantially decreasing the time scale of the MR explosion. The energy of the supernova increases with the core’s mass and initial rotational energy.     

Evaluation of distributed recharge in an upland semi-arid karst system: the West Bank Mountain Aquifer,Middle East

Assessment of recharge in a structurally complex upland karst limestone aquifer situated in a semi-arid environment is difficult. Resort to surrogate indicators such as measurement of spring outflow and borehole discharge, is a common alternative, and attempts to apply conventional soil moisture deficit analysis may not adequately account for the intermittent spate conditions that arise in such environments. A modelling approach has been made using the West Bank Mountain Aquifer system in the Middle East as a trial. The model uses object oriented software which allows various objects to be switched on and off. Each of the main recharge processes identified in the West Bank is incorporated. The model allows either conventional soil moisture deficit analysis calculations or wetting threshold calculations to be made as appropriate, and accommodates both direct recharge and secondary recharge. Daily time steps enable recharge and runoff routing to be calculated for each node. Model runs have enabled a series of simulations for each of the three aquifer basins in the West Bank and for the whole of the West Bank. These provide recharge estimates comparable to those prepared by earlier workers by conventional means. The model is adaptable and has been successfully used in other environments.     

Microbial mineralization and assimilation of black carbon: Dependency on degree of thermal alteration

Black carbon is degraded slowly in the environment and its formation can therefore be an effective sink for atmospheric CO₂. This study examined whether charcoal is assimilated by microorganisms or not and estimated the rate of mineralization depending on the degree of thermal alteration of the black carbon. Charcoals were produced at three different temperatures from homogeneously ¹⁴C labelled plant material and incubated in soil, and ¹⁴C in the evolved CO₂ and the microbial biomass was measured. Unlike parallel plant samples, CO₂ evolution from the charcoals showed no lag phase, but a period of faster CO₂ evolution for the first 5–8 days followed by a period of slow evolution. The mineralization of charcoal appeared to decrease with increasing temperature at which it was produced. This was also the case after the initial period of fast CO₂ evolution. With the techniques used, it was not possible to observe any microbial assimilation of charcoal, either because it did not occur, or because the methods used were not sufficiently sensitive. However, the lack of a lag phase in the CO₂ evolution from the charcoals is in line with earlier evidence that charcoal is initially oxidized at the surfaces by abiotic processes.     

Geochemistry of magmatic rocks of the Koksharovka alkaline-ultrabasic massif,primorye, and results of trace-element modeling

New geochemical data are presented on the magmatic rocks of the Late Jurassic Koksharovka alkaline-ultrabasic massif, which is associated with deposits of vermiculite, apatite, V-bearing titanomagnetite, and placer isoferroplatinum. The REE geochemistry and strontium, oxygen, and carbon isotopic composition of carbonatites and related ijolites and pyroxenites, together with geological observations, point to the magmatic origin of the Koksharovka carbonatites. The origin of associated magmatic rocks is discussed. Trace element modeling of partial melting of mantle sources was conducted to decipher the genesis of the melts of the Koksharovka carbonatites and host titanite-kaersutite pyroxenites.     

Paleomagnetic studies of the Late Mesozoic deformation stage in the southern Primorye region

The analysis of paleomagnetic data available for the southern Primiorye region revealed that the studied objects were magnetized under regional remagnetization presumably during the Late Mesozoic folding and this magnetization can be interpreted as being synfolding. The interpretation is based on the parameter that characterizes the folding completion degree immediately before regional remagnetization. It is shown that the relaxation of Late Mesozoic horizontal stresses was irregular. The obtained estimates of the degree of folding completion are consistent with the available geological data and Talitskii’s model for tectonic deformations.