45 research outputs found
Structural complexity at and around the Triassic-Jurassic GSSP at Kuhjoch, Northern Calcareous Alps, Austria
One of the key requirements for a Global Stratotype Section and Point (GSSP) is the absence of tectonic disturbance. The GSSP for the Triassic–Jurassic system boundary was recently defined at Kuhjoch, Northern Calcareous Alps, Austria. New field observations in the area of the Triassic–Jurassic boundary GSSP site demonstrate that the overturned, tight, and almost upright Karwendel syncline was formed at semibrittle deformation conditions, confirmed by axial planar foliation. Tight to isoclinal folds at various scales were related to a tectonic transport to the north. Brittle faulting occurred before and after folding as confirmed by tilt tests (the rotation of structural data by the average bedding). Foliation is ubiquitous in the incompetent units, including the Kendlbach Formation at the GSSP. A reverse fault (inferred to be formed as a normal fault before folding) crosscuts the GSSP sections, results in the partial tectonic omission of the Schattwald Beds, and thus makes it impossible to measure a complete and continuous stratigraphic section across the whole Kendlbach Formation. Based on these observations, the Kuhjoch sections do not fulfil the specific requirement for a GSSP regarding the absence of tectonic disturbances near boundary level
Integrative enrichment analysis: a new computational method to detect dysregulated pathways in heterogeneous samples
Paleogeographic evolution of the Southern Pannonian Basin: 40Ar/39Ar age constraints on the Miocene continental series of notthern Croatia
The Pannonian Basin, originating during the
Early Miocene, is a large extensional basin incorporated
between Alpine, Carpathian and Dinaride fold-thrust belts.
Back-arc extensional tectonics triggered deposition of up to
500-m-thick continental fluvio-lacustrine deposits distributed
in numerous sub-basins of the Southern Pannonian
Basin. Extensive andesitic and dacitic volcanism accompanied
the syn-rift deposition and caused a number of
pyroclastic intercalations. Here, we analyze two volcanic
ash layers located at the base and top of the continental
series. The lowermost ash from Mt. Kalnik yielded an
40Ar/39Ar age of 18.07 ± 0.07 Ma. This indicates that the
marine-continental transition in the Slovenia-Zagorje
Basin, coinciding with the onset of rifting tectonics in the
Southern Pannonian Basin, occurs roughly at the Eggenburgian/
Ottnangian boundary of the regional Paratethys
time scale. This age proves the synchronicity of initial
rifting in the Southern Pannonian Basin with the beginning
of sedimentation in the Dinaride Lake System. Beside
geodynamic evolution, the two regions also share a biotic
evolutionary history: both belong to the same ecoregion,
which we designate here as the Illyrian Bioprovince. The
youngest volcanic ash level is sampled at the Glina and
Karlovac sub-depressions, and both sites yield the same
40Ar/39Ar age of 15.91 ± 0.06 and 16.03 ± 0.06 Ma,
respectively. This indicates that lacustrine sedimentation in
the Southern Pannonian Basin continued at least until the
earliest Badenian. The present results provide not only
important bench marks on duration of initial synrift in the
Pannonian Basin System, but also deliver substantial
backbone data for paleogeographic reconstructions in
Central and Southeastern Europe around the Early–Middle
Miocene transition
The influence of the load on the hardness
The objective of the submitted paper is to analyze the influence of the load on the calibration of micro-hardness and hardness testers. The results were validated by Measurement Systems Analysis (MSA), Analysis of Variance (ANOVA) and Z-score. The relationship between the load and micro-hardness in calibration of micro-hardness testers cannot be explained by Kick's Law (Meyer's index "n" is different from 2). The conditions of Kick's Law are satisfied at macro-hardness calibration, the values of "n" are close to 2, regardless of the applied load. The apparent micro-hardness increases with the increase of the load up to 30 g; the reverse indentation size effect (ISE) behavior is typical for this interval of the loads. The influence of the load on the measured microhardness is statistically significant for majority of calibrations
Late Triassic to Early Jurassic palaeogeography and eustatic history in the NW Tethyan realm: New insights from sedimentary and organic facies of the Csovar Basin (Hungary)
Sedimentary and organic facies of a continuous Late Triassic–Early Jurassic toe-of-slope to basin succession of the NE Transdanubian Range (N Hungary) was studied in order to reconstruct the palaeogeographical and eustatic evolution of the Csővár Basin, an intraplatform basin of the NW Neotethys margin. Characteristic facies successions point to sea-level changes of different hierarchies. Cyclic patterns, inferred to result from orbital eccentricity forcing, are also reflected in the stratigraphical distribution of sedimentary organic matter. Furthermore, both palaeontological and isotope data document drastic climatic changes around the Triassic–Jurassic boundary. Detecting sea-level changes leads to a more accurate interpretation of the Late Triassic palaeogeographic setting and evolution of the Transdanubian Range's carbonate platform. Our integrated sedimentological and palynological data suggest a complex topography and dynamic sea-level history, which contradicts a previous model of broad, uniform platform setting and lack of any major drowning and emersion events during the Late Triassic
238U/235U systematics in terrestrial uranium-bearing minerals
The present-day 238U/235U ratio has fundamental implications for uranium-lead geochronology and cosmochronology. A value of 137.88 has previously been considered invariant and has been used without uncertainty to calculate terrestrial mineral ages. We report high-precision 238U/235U measurements for a suite of uranium-bearing minerals from 58 samples representing a diverse range of lithologies. This data set exhibits a range in 238U/235U values of >5 per mil, with no clear relation to any petrogenetic, secular, or regional trends. Variation between comagmatic minerals suggests that 238U/235U fractionation processes operate at magmatic temperatures. A mean 238U/235U value of 137.818 ± 0.045 (2σ) in zircon samples reflects the average uranium isotopic composition and variability of terrestrial zircon. This distribution is broadly representative of the average crustal and “bulk Earth” 238U/235U composition
The Fluidity of Al-Si Alloy: Computer Simulation of the Influence of Temperature, Composition, and Pouring Speed
The purpose of this study is to identify relationships between the values of the fluidity obtained by computer simulation and by an experimental test in the horizontal three-channel mould designed in accordance with the Measurement Systems Analysis. Al-Si alloy was a model material. The factors affecting the fluidity varied in following ranges: Si content 5 wt.% – 12 wt.%, Fe content 0.15 wt.% – 0.3 wt. %, the pouring temperature 605°C-830°C, and the pouring speed 100 g · s-1 – 400 g · s-1. The software NovaFlow&Solid was used for simulations. The statistically significant difference between the value of fluidity calculated by the equation and obtained by experiment was not found. This design simplifies the calculation of the capability of the measurement process of the fluidity with full replacement of experiments by calculation, using regression equation
Published geological map
BC Ministry of Energy, Mines and Petroleum Resources, Geoscience Map 2006-2Base Map Information Base map has been produced from digital TRIM (Terrain Resource Inventory Management) 1:20 000 topographic database provided by the British Columbia Ministry of Environment, Lands and Parks. North American Datum (NAD) 1983. Universal Transverse Mercator Projection (Zone 9). Elevation in metres above mean sea level. Contour interval 100m