Journal of GEOsciences Table of Contents for the Journal of GEOsciences. List of articles from the latest print issue.http://www.jgeosci.orgen-US Journal of GEOsciences <![CDATA[ (Pleasant) consequences of digital printing and other news ]]> Janoušek V; Vol. 63, issue 1, page: 1
Dear authors, readers and supporters,
As you know, in our Journal of Geosciences we strive to bring you scientific papers of both high technical and scientific standard. At the same time, we try to keep the expenses, both to the authors and to the Society, minimal. Therefore, we have been experimenting with digital printing for some time already and we believe now that the resulting quality is well comparable with the classical printing. In addition, the digital technology allows us to optimize the number of hardcopies produced, just printing the older issues on demand.
But there are even more pleasant consequences - the digital printing will enable us to revise and simplify the price list for colour printing - from the issue 3/2018, we shall charge mere 300 CZK/15 EUR/18 USD per colour page printed. For a single page, this represents a drop to almost one tenth of the former price. Moreover, colour illustrations intended solely for the online PDF are always free.
Lastly, the page charges of 500 CZK/20 EUR, as introduced from the issue 1/2013, remain unchanged. These still apply to every printed page exceeding the limit of sixteen, which is free for everyone. However, if the corresponding author is a paying member of the Czech Geological Society and the extended length is justified by the scientific merit, no extra fee is required.
The last change that you may have noticed is the substantial reconstruction of the Internal Editorial Board (the external one shall follow soon). This reflects the fact that very much the same team has worked hard since the new format of the Journal has been introduced, i.e. some for 11 years. Over this time, some of us got (re)tired, and everyone got much more exact knowledge what contributions and topics we have to deal with; even some brand new fields have emerged meanwhile.
I have to mention at this place a very sad loss we have suffered recently - Stanislav Vrána, the former editor-inchief of our predecessor, Journal of the Czech Geological Society, sadly has passed away on March 24, 2018, aged 82 years. We are sure that without his vision, energy, tireless editorial and organizational work, the Journal of Geosciences would certainly not exist... Requiescat in pace! ]]> Editorial
<![CDATA[ Structure of the Carboniferous Altenberg-Teplice Caldera (Eastern part of the Krušné hory/Erzgebirge Mts.) revealed by combined airborne and ground gamma-ray spectrometry ]]> Gnojek I, Sedlák J, Rapprich V, Skácelová Z, Mlčoch B, Krentz O, Casas-García R; Vol. 63, issue 1, pages 3 - 20
The airborne gamma-ray spectrometry images from the Czech and German parts of the Carboniferous Altenberg-Teplice Volcanic Complex (ATVC) - both obtained during independent surveying campaigns - were merged to display the structure of the caldera fill (dominated by rhyolitic ignimbrites) and associated intrusive bodies. The airborne systematic measurements were supported by the ground- and laboratory gamma-ray spectrometry analyses (K, U, Th) of representative lithologies from outcrops and drill-cores.
Significant differences were identified between the younger and older (post- and pre-caldera respectively) intrusive complexes related to the ATVC. The younger Schellerhau granite displays 1.5-3.0× higher concentrations of radioactive elements than the older Fláje granite.
The ATVC was found to be split by the NW-SE trending Altenberg Fault into a southern and a northern segment that expose different stratigraphic levels of the caldera’s fill. The individual types of rhyolite ignimbrites defined in the Czech part of the ATVC are characterized by distinct concentrations of natural radioactive elements which enable identification of the individual types from the airborne gamma-spectrometry image. These characteristics were compared to data obtained from the German part, and several lithological types were unified to common units.
A single Th-rich unit (Pramenáč type in Czech part, Lugstein type in Germany and Teplice Rhyolite TR3a in Mi-4 borehole) can be traced across the entire caldera and may serve as the principal correlation member. Inclusion of the Vrchoslav type into this TR3a unit remains speculative due to lack of data, and further petrological research is required. On the other hand, Vlčí kámen and Medvědí vrch types from opposite sides of the caldera display identical properties allowing to merge them into a common unit TR3b overlain by the youngest unit TR4 (Přední Cínovec type) - restricted to the Czech territory. This result may suggest partly synclinal structure within the southern ATVC segment. The TR4 unit has a strong compositional tendency towards the post-ignimbrite granite porphyry intrusions.
Some lithotypes in the northern segment (e.g., Buschmühle) do not have counterparts on the Czech side and most likely represent an independent volcanic unit in the northern part of the caldera.
The uniform composition of the rhyolitic rocks observed in the entire profiles of the drillings located in the Town Teplice (TP-39 reaching 1170 m depth) may suggest that the main feeding conduit system for the TR4 ignimbrite was located within the Teplice-Lahošť horst area. ]]> Original Paper
<![CDATA[ Evolution of the arc-derived orthogneiss recorded in exotic xenoliths of the Körös Complex (Tisza Megaunit, SE Hungary) ]]> Tóth TM, Schubert F; Vol. 63, issue 1, pages 21 - 46
The pre-Neogene basement of the Pannonian Basin consists of different terranes, which became juxtaposed during subsequent tectonic events from the Palaeozoic up to the Miocene. One of the largest terranes is the Tisza Megaunit, an assemblage of metamorphic blocks of different lithology and P-T-t-d evolution. In the present study, petrological data from orthogneiss bodies representing numerous neighbouring crystalline highs hidden beneath sediments of the Pannonian Basin are presented.
Characteristic textures and mineral assemblages of the orthogneisses are identical in the whole studied area. Based on geochemical data, the orthogneiss precursor was quartz monzodiorite to granodiorite. The metamorphic conditions were estimated at around 580-600 °C based on two-feldspar thermometry, co-existing amphibole-plagioclase equilibria, and Theriak/Domino modelling. The most conspicuous petrographic feature of the orthogneiss is the presence of various types of xenoliths and xenocrysts. Most xenoliths are mafic and represent eclogite and diverse amphibolite varieties, but ultramafic, carbonate, and felsic granulite also occur. All record LP-HT (low pressure, high temperature) overprint under the same conditions at which the orthogneiss formed.
Evolution of the orthogneiss body can be understood in the frame of the subduction-accretionary model. Xenoliths of various origins could represent an accretionary prism material that was picked up by the ascending granitoid melt that was subsequently solidified and metamorphosed to an orthogneiss. ]]> Original Paper
<![CDATA[ Automated mineralogy and petrology - applications of TESCAN Integrated Mineral Analyzer (TIMA) ]]> Hrstka T, Gottlieb P, Skála R, Breiter K, Motl D; Vol. 63, issue 1, pages 47 - 63
The collection of representative modal mineralogy data as well as textural and chemical information on statistically significant samples is becoming essential in many areas of Earth and material sciences. Automated Scanning Electron Microscopy (ASEM) systems provide an ideal solution for such tasks. This paper presents the methods and techniques used in the recently developed TESCAN Integrated Mineral Analyzer (TIMA-X) with Version 1.5 TIMA software. The benefits from the use of a fully integrated quantitative energy-dispersive X-ray spectrometry (EDS) and an advanced statistical approach to ASEM systems are demonstrated. Typically, the system can handle more than 500,000 X-ray events per second. Using a common spectral total of 1000 events this represents the acquisition of 500 spectra per second. A number of measurement modes is available to make the most effective use of these spectra depending on the application.
For a back-scattered electrons (BSE) map combined with EDS data with spatial resolution of 10 µm, this represents the high-resolution measurement of c. 1 cm2 of a thin section or a polished rock surface in 30 minutes. A patented X-ray spectrum clustering algorithm that lowers the chemical detection limit is described and an example of its use is shown. The modal and textural (liberation, association, size etc.) data produced are statistically robust and provide information across a broad range of Earth and material sciences. A comparison with some other available instruments is also provided together with a number of case studies. ]]> Original Paper
<![CDATA[ The crystal structure of uranyl-oxide mineral schoepite, [(UO2)4O (OH)6]( H2O)6, revisited ]]> Plášil J; Vol. 63, issue 1, pages 65 - 73
New single-crystal X-ray diffraction experiments have revealed that the crystal structure of schoepite, one of the more common U-oxide minerals, is centrosymmetric, rather than acentric as reported in the past. Schoepite is orthorhombic, space group Pbca, a = 16.7810(5), b = 14.7044(4), c = 14.2985(5) Å, with V = 3528.22(19) Å3 and Z = 8. Its structure was solved by charge-flipping algorithm and refined to an agreement index (R) of 4.7 % for 4662 unique reflections collected using microfocus X-ray source. Schoepite structure, in line with its previous determination, is based upon U-O-OH sheets of the fourmarierite topology and an interlayer filled only by molecular H2O. The complexity calculations show that the difference in complexity values between schoepite, [(UO2)4O(OH)6](H2O)6, and metaschoepite, [(UO2)4O(OH)6](H2O)5, are much smaller (about 100 bits/cell) then considered previously (about 1000 bits/cell). Such small difference is in line with the easy transformation of schoepite to metaschoepite under ambient conditions and a joint occurrence of both minerals. ]]> Original Paper