Complex examination of the Upper Paleozoic siliciclastic rocks from southern Transdanubia, SW Hungary—Mineralogical, petrographic, and geochemical study

A vertical section of Upper Paleozoic sandstones from southern Transdanubia (Mecsek-Villány area, Tisza mega-unit, Hungary) has been analyzed for major and trace elements, including rare earth elements (REEs). In addition, the clay mineralogy of the sandstone samples and the petrography and geochemistry of gneiss and granitoid clasts extracted from the associated conglomerates have been determined. Geochemistry of the sandstone samples analyzed in this study shows that these rocks were predominantly derived from a felsic continental source; nevertheless, compositions vary systematically up-section. The Pennsylvanian (Upper Carboniferous) Téseny Formation has higher SiO(2) and lower Na(2)O, CaO, Sr, high field strength element (HFSE), and ΣREE contents relative to the Permian strata. Its high K(2)O and Rb contents together with the presence of abundant illite-sericite suggest a potassium metasomatism in this formation. Clay mineralogy and large ion lithophile element (LILE) contents of the Lower Permian Korpád Formation vary spatially and are interpreted as local variations in composition of the source region and postdepositional conditions. Zr and Hf abundances and REE patterns, however, show that this formation was derived from mature upper continental crust. The Upper Permian Cserdi Formation has higher TiO(2), Th, U, Y, Cr, and heavy (H) REE contents, and higher Cr/Th and Cr/Zr ratios relative to the underlying formations. These trends can be explained by a sedimentary system dominated by highly weathered detritus derived from combined recycled-orogen, basement-uplift, and volcanic-arc provenance in the Téseny Formation, with an increased proportion of less weathered detritus derived from combined volcanic and basement-uplift provenances in the Permian formations. Characteristics of the Cserdi unit may reflect relatively proximal derivation from a felsic volcanic source

Lead isotope evolution of the Central European upper mantle: Constraints from the Bohemian Massif

This study focuses on Pb isotope data and whole-rock geochemistry of intrusive and extrusive volcanic rocks of the Bohemian Massif that sampled the upper mantle. Special attention is paid on whether Late Palaeozoic to Quaternary Central European mantle-derived rocks sampled different mantle sources on a local to regional scale and through time.Tato studie se zabývá Pb izotopovými daty a horninovou geochemií intruzivních i výlevných vulkanických hornin Českého masivu, které vzorkovaly svrchní plášť. Speciální důraz je kladen na to, zda pozdně paleozoické až kvartérní středoevropské horniny odvozené z pláště vzorkují odlišné plášťové zdroje v lokálním až regionálním měřítku a v průběhu času

Constraining long-term denudation and faulting history in intraplate regions by multisystem thermochronology: An example of the Sudetic Marginal Fault (Bohemian Massif, central Europe)

The Rychlebské hory Mountain region in the Sudetes (NE Bohemian Massif) provides a natural laboratory for studies of postorogenic landscape evolution. This work reveals both the exhumation history of the region and the paleoactivity along the Sudetic Marginal Fault (SMF) using zircon (U-Th)/He (ZHe), apatite fission track (AFT), and apatite (U-Th)/He (AHe) dating of crystalline basement and postorogenic sedimentary samples. Most significantly, and in direct contradiction of traditional paleogeographic reconstructions, this work has found evidence of a large Cretaceous sea and regional burial (to >6.5 km) of the Carboniferous-Permian basement in the Late Cretaceous (~95–80 Ma). During the burial by sediments of the Bohemian Cretaceous Basin System, the SMF acted as a normal fault as documented by offset ZHe ages across the fault. At 85–70 Ma, the basin was inverted, Cretaceous strata eroded, and basement blocks were exhumed to the near surface at a rate of ~300 m/Ma as evidenced by Late Cretaceous–Paleocene AFT ages and thermal modeling results. There is no appreciable difference in AFT and AHe ages across the fault, suggesting that the SMF acted as a reverse fault during exhumation. In the late Eocene–Oligocene, the basement was locally heated to <70°C by magmatic activity related to opening of the Eger rift system. Neogene or younger thermal activity was not recorded in the thermochronological data, confirming that late Cenozoic uplift and erosion of the basement blocks was limited to less than ∼1.5 km in the study area

Structures Related to the Emplacement of Shallow-Level Intrusions

A systematic view of the vast nomenclature used to describe the structures of shallow-level intrusions is presented here. Structures are organised in four main groups, according to logical breaks in the timing of magma emplacement, independent of the scales of features: (1) Intrusion-related structures, formed as the magma is making space and then develops into its intrusion shape; (2) Magmatic flow-related structures, developed as magma moves with suspended crystals that are free to rotate; (3) Solid-state, flow-related structures that formed in portions of the intrusions affected by continuing flow of nearby magma, therefore considered to have a syn-magmatic, non-tectonic origin; (4) Thermal and fragmental structures, related to creation of space and impact on host materials. This scheme appears as a rational organisation, helpful in describing and interpreting the large variety of structures observed in shallow-level intrusions

The largest volcanic eruptions on Earth

Do najważniejszych wskaźników umożliwiających określanie rozmiarów erupcji wulkanicznych należą: ilość materiału piroklastycznego wyrzuconego w czasie erupcji (objętość tefry); objętość magmy - objętość produktów erupcji z pominięciem ich porowatości (ang. Dense Rocvk Equivalent, DRE); oraz magnituda, M - definiowana jako logarytm dziesiętny z masy magmy minus 7. Objętość tefry jest podstawą skali eksplozyjności wulkanicznej (ang. Volcanic Explosivity Index, VEI), w której najsłabsze erupcje (VEI=0), wyrzucają 103km3 tefry. Wybuch wulkanu Tambora na Sumatrze w 1815 r. (objętość tefry =160km3, VEI=7, DRE=50km3, M=7.3) stanowił najsilniejszą erupcję eksplozyjną w czasach historycznych. Największe historyczne wylewy lawy miały miejsce na Islandii, np. ze szczeliny Laki w 1783 r. (DRE=15km3, M=6.5). Te niemal współczesne erupcje stanowiły skromną próbkę możliwości natury. Ludzkość nie doświadczyła dotąd największych możliwych erupcji, które powodują zniszczenia terenów o rozmiarach kontynentu i globalne zmiany klimatyczne. Supererupcje kalder La Garita w USA 28 mln lat temu (DRE=4500 km3, M=9.2) oraz Toba na Sumatrze 74 tys. lata temu (DRE=2700km3, M=8.8) były, odpowiednio, 90 i 54 razy silniejsze od erupcji Tambora. Ostatnio udokumentowano ślady jeszcze potężniejszych erupcji na obszarach tzw. wielkich prowincji magmowych. Na Dekanie stwierdzono największe wylewy lawy (DRE=9300km3, M=9.4) o wieku 64.8 mln lat, a w prowincji Parana-Etendeka rozpoznano największe ignimbryty, produkty wielkich erupcji eksplozyjnych (DRE do 8587 km3, M do 9.3) o wieku 132 mln lat. Erupcje o takiej skali zbliżają się zapewne do największych możliwych na naszej planecie, co uwarunkowane jest możliwością rozwoju odpowiednio dużych zbiorników magmy w skorupie Ziemi.The most important indices of volcanic eruption size include: erupted pyroclastic material volume (tephra volume); magma volume - the volume of euptive products excluding their porosity (Dense Rock Equivalent, DRE); and the magnitude, M - defined as the common logarithm of erupted magma mass minus 7. The tephra volume is the basis of the Volcanic Explosivity Index (VEI) scale. The weakest eruptions (VEI=0) produce 103km3 of tephra. Eruption of Tambora in 1815 (tephra volume = 160km3, VEI=7, DRE=50km3, M=7.3) was the strongest explosive eruption in historical times. The largest historical lava effusions occurred on Iceland, e.g. from the Laki fissure in 1783 (DRE=15km3, M=6.5). These almost recent eruptions were only modest samples of nature's powers. Mankind has not yet witnessed the largest possible eruptive events, which devastate continent-sized terrains and result in global climatic changes. Supereruptions of La Garita caldera, Colorado, USA, at 28 Ma (DRE=4500 km3, M=9.2) and Toba, Sumatra, at 74 ka (DRE=2700km3, M=8.8) were 90 and 50 times, respectively, stronger than Tambora. Products of even more powerful eruptions were recently recognized in areas of so called Large Igneous Provinces (LIPs). Largest lava effusions (DRE=9300km3, M=9.4) dated at 64.8 Ma were recognized at Deccan, and largest ignimbrites (deposits of giant explosive eruptions), dated at 132 Ma, were identified at the Parana-Etendeka province. Eruptions of that size approach the limit of largest eruptions possible on our planet, which is probably determined by the ability of formation of crustal magma reservoirs large enough