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Abstract

A total of 1,514 fossil bones were studied from the Vaskapu II rock shelter (Bükk Mountains, North Hungary). The objective of this study was to investigate those processes of bone modification that were important in the dispersal, destruction and preservation of bone in the deposit. Size-selective taphonomic processes were detected in the accumulation of vertebrate remains. The fossils were transported by water through a 15 m high fissure system above the locality during repeated precipitation and thawing. Size-sorting of the bones occurred within the fissures. During this process the fossils were damaged and fragmented and the remains were eventually emplaced into the Vaskapu II rock shelter. The size-sorting is statistically established by a method based on the chisquare test. This method clearly describes the differences between the life and death assemblages.

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Acta Geologica Hungarica
Authors:
Tamás Mikes
,
István Dunkl
,
Wolfgang Frisch
, and
Hilmar von Eynatten

We present the main petrographic and geochemical features of the Lower to Middle Eocene turbiditic sandstones from the northwestern portion of the External Dinaride flysch basin. Sampled areas cover SW Slovenia (Vipava and Brkini Basins) and the Istrian Peninsula (Trieste-Koper and Pazin Basins). Framework constituents of the lithic arenites reveal low-grade metamorphic, acidic plutonic, and to a lesser extent, mafic volcanic and ultrabasic sediment sources, with evidence for a small degree of sediment recycling as well. Among the processes that commonly influence sediment compositions, weathering in the source and sorting were probably negligible, but carbonate contribution of detrital or intrabasinal origin diluted the siliciclastic portions to various degrees. Main and trace element compositional data agree well with petrography and clearly indicate the predominance of felsic, crustal source lithologies. Exposed mafic-ultramafic source units were volumetrically less important.  From the Early Paleogene, extensive sediment mixing occurred in front of the Dinaride orogenic thrust wedge, with the components derived from different Dinaride units of felsic crystalline basement, platform carbonates and ophiolite. In the Eocene, a likely source of the mafic-ultramafic detritus was the Jurassic ophiolitic mélange in the NE Dinarides.

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The Jakabhegy Sandstone Formation, known for a long time at surface in the western part of the Mecsek Mts, SE Transdanubia, was encountered by several boreholes in the second half of the 20th century in a large part of SE Transdanubia, during exploration for uranium ore in the Upper Permian formations in its subcrop. The formation is made up of five informal lithologic units, from the base upward the "main conglomerate", the "gravelly sandstone", the "pale sandstone" with "conglomerate 2" at its base, then the "red-brown siltstone and sandstone" and at the top the "variegated sandstone" (units "a, b, c, d, e"). Grain size becomes finer upsection, the grains are medium-rounded, and sorting generally improves upward. Planar cross-bedding of varying size is characteristic. The Jakabhegy Sandstone Formation occurs in two types of development. In the case of complete development, all the lithologic units are present, but the lower two ("a+b") do not overlap the Late Permian-Early Triassic Kővágószőlős Sandstone Formation. The case in which the formation is only built up of units "c+d+e" is called incomplete development. In both cases erosional unconformity and hiatus occur between the formation and its underlying unit, while showing continuous transition toward its cover, the Patacs Siltstone Formation. On the basis of the sedimentological features the main conglomerate and the gravelly sandstone ("a+b") were deposited in fluvial facies, "c" in wave-dominated, and "d" and "e" in tide-dominated delta facies. In the clast composition of the Jakabhegy Sandstone, the quartz predominates, the amount of K-feldspars is much smaller and plagioclase is almost completely absent. The rock debris is derived from metamorphic, acidic volcanic and plutonic rocks. According to the quartz/feldspar ratio, the most mature sandstone layers can be found in the central beds of unit "c" and appear in incomplete development at the base of the sequence, locally in quartz arenite quality. The fossil content of the Jakabhegy Sandstone consists almost exclusively of microflora found in the gray layers of the two upper units ("d+e"). According to the palynological investigation, unit "d" and the lower part of unit "e" represent the Spathian substage of the Olenekian stage, while the upper part of "e" already belongs to the Lower Anisian. Downsection, microflora-free red sediments are encountered down to the layers below the upper member of the underlying formation. In the microflora found in these lowest levels, Lower Triassic spores appear with dramatic suddenness and in remarkable quantity, alongside decrease in the amount of Upper Permian pollen.

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A continuous Sarmatian/Pannonian boundary section, which rarely crops out within the Pannonian Basin, was studied near Oarba de Mures/Marosorbó. Alternating beds of clay marl, calcareous marl, siltstone, sandstone and andesitic tuff are present up to a thickness of about 100 m. Traditionally the Sa/Pa boundary was placed at the top of the last significant tuff layer, which has been confirmed by mollusk-bearing strata a few meters above belonging to the "Lymnocardium" praeponticum Zone. This zone is coeval with the Early Pannonian Mecsekia ultima dinoflagellate zone and the C5r magnetic polarity zone. Three ranks of cyclicity connected to sediment gravity flows are present in the outcrops. Coarse silt to sandstone beds were formed by low-density turbidity currents. These individual events represent "dilution cycles" connected to the intensity and abundance of turbidity currents. Turbiditic beds, some 2-5 m-thick series of sandstones, form coarsening/thickening upward cycles of 8-20 m of thickness. This cyclicity may reflect autocyclic lobe switching in deep lacustrine fans. The lowermost 70 m of the succession comprises a major thickening to thinning cycle, while the uppermost part of the sequence seems to represent a longer turbidite-free interval. The last may either reflect climatically-driven allocyclic lake-level variations or impulses of hinterland structural evolution (tectonic activity vs. quiescence). The background sediments show two sorts of seemingly independent rhythmicity: there is marl with variable carbonate content, occasionally forming a few cm of thickening-upward series of calcareous marl, and it also shows various grades of bioturbation. Calcareous marl is often associated with the appearance of fibrous gypsum laminae. The alternating carbonate content of the marl might be generated either by "production cycles" in the photic zone over which the climatic influence is straightforward, or they were formed as the first products of the evaporite succession from hypersaline bottom waters. The lack of bioturbation combined with gypsum may reveal hypersaline and/or dysaeroabic abiotic bottom conditions. These also indicate that turbidity currents had transported not only terrestrial sediments but less saline, O2-bearing water down to the lake floor, interrupting the biota-poor periods. The salinity of the bottom waters in the deepest basin segments might significantly differ from that of the main water mass, and might have been regulated by the composition and amount of ions dissolved from Mid-Miocene salt diapirs cropping out at the lake bottom elsewhere. Accumulation of hypersaline bottom waters may also be facilitated by climatically-determined density stratification of the lake water.

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Range (NE Spain): implications for source-area weathering, sorting, provenance, and tectonic setting. - Chemical Geology, 168, pp. 135 - 150 . Geochemistry of Precambrian and Paleozoic siliciclastic rocks from the Iberian Range

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-supported, fine-grained, felsitic ash tuff with coated particles lmLT Lithic-rich, massive, strongly sericitized, poorly-sorted volcaniclastics vlava-likeT Spherulitic vitrophyric lava-like ash tuffs Petrographic studies, including mineralogical and textural

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., M. J. Mayayo, C. Fernandez-Nieto, J. M. Gonzalez Lopez 2000: Geochemistry of Precambrian and Paleozoic siliciclastic rocks from the Iberian Range (NE Spain): implications for source-area weathering, sorting, provenance, and tectonic setting

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. H.G. Herbig B. Mamet 1994 Hydraulic sorting of microbiota in calciturbidites. A Dinantian case study from the Rheinische Schiefergebirge, Germany

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-group and inter-group mean distances Figure 5. Distance matrix rearranged. Left: sorted according to clusters 1 to 3; right: sorted according to RBMP class. Instead of indicating the unique numbers, values <2 transformed units are dimmed black, and the rest

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understand that this is not simply a replication of data. Of the 986 data, the actual “measured” data is only 493. Automatic sorting of the data is performed by Steiner weighting within the CGWI inversion. The results presented in Fig. 3d show a mean

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