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A well-preserved set of mid-Miocene scoria-and tuff-cones and their feeders crops out in the Jičín Volcanic Field, Czech Republic. The Trosky volcano is a scoria cone that has been eroded to reveal the volcano's feeder system. This edifice offers the opportunity to improve the understanding how magma is transported through a monogenetic pyroclastic cone. Physical volcanology, petrology, anisotropy of magnetic susceptibility (AMS) and paleomagnetic data were combined to study of the erosional remnant of the Trosky volcano. Selective erosion has exposed spectacular remnants of a twin scoria cone intruded by late volcanic spines. These spines host a medieval castle that is a landmark of the Bohemian Paradise area in northeast Czech Republic. Paleomagnetic and AMS samples were collected from 29 sites, including the conduits, lava flows, and dikes intruding the conduits. The AMS data reveal magmatic flow directions that were variable, vertical (upward and downward) as well as subhorizontal (into and away from the volcano). Paleomagnetic data from the conduits and lava flows yield reverse polarity directions that are statistically indistinguishable from the expected mid-Miocene reverse polarity field direction. The dikes, however, show both normal and reverse polarity magnetizations that are statistically distinct from the expected field direction. We documented significant compositional variability of lavas erupted from the Trosky volcano, in contrast to the uniform composition of later plugs and dikes. The variability of lavas (olivine-rich, olivinepoor, clinopyroxene-rich and olivine-clinopyroxene equal types) suggests magma storage in a zoned shallow magma chamber (containing olivine-or clinopyroxene-depleted/enriched zones). The combined results and the presence of both normal and reverse polarity magnetizations from the dikes crosscutting the volcano indicate that this monogenic system was long-lived. Taken together, the simple external structure of monogenetic volcanoes often hides a rather complex magmatic plumbing system that dynamically evolves during their lifespan.

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Abstract:Image data sharpening is a challenging field of remote sensing science, which has become more relevant as high spatial-resolution satellites and superspectral sensors have emerged. Although the spectral property is crucial for mineral mapping, spatial resolution is also important as it allows targeted minerals/rocks to be identified/interpreted in a spatial context. Therefore, improving the spatial context, while keeping the spectral property provided by the superspectral sensor, would bring great benefits for geological/mineralogical mapping especially in arid environments. In this paper, a new concept was tested using superspectral data (ASTER) and high spatial-resolution panchromatic data (WorldView-2) for image fusion. A modified Principal Component Analysis (PCA)-based sharpening method, which implements a histogram matching workflow that takes into account the real distribution of values, was employed to test whether the substitution of Principal Components (PC1-PC4) can bring a fused image which is spectrally more accurate. The new approach was compared to those most widely used-PCA sharpening and Gram-Schmidt sharpening (GS), both available in ENVI software (Version 5.2 and lower) as well as to the standard approach-sharpening Landsat 8 multispectral bands (MUL) using its own panchromatic (PAN) band. The visual assessment and the spectral quality indicators proved that the spectral performance of the proposed sharpening approach employing PC1 and PC2 improve the performance of the PCA algorithm, moreover, comparable or better results are achieved compared to the GS method. It was shown that, when using the PC1, the visible-near infrared (VNIR) part of the spectrum was preserved better, however, if the PC2 was used, the short-wave infrared (SWIR) part was preserved better. Furthermore, this approach improved the output spectral quality when fusing image data from different sensors (e.g., ASTER and WorldView-2) while keeping the proper albedo scaling when substituting the second PC.