The master thesis is focused on the semiquantitative study of the fossil association of the stratigraphically lowest layer No. 3 from the channel sample from the Ejpovice locality, where in the southern bank of the flooded quarry, the Dobrotivá Formation of the Ordovician of the Prague Basin is exposed in the thickness of several meters. The thesis briefly summarizes basic knowledge about the fossil associations of the Dobrotivá Formation, its lithology, stratigraphy and previous paleontological research at studied locality. Paleoecology of the fauna recorded in studied material is described. The main part of the thesis is focused on the taphonomy and associations of the fossils recorded in studied material. In the final part of the thesis, the overall fossil association is characterized depending on the paleoecology and taphonomy of preserved fossils, and the model of the paleoenvironment at the Ejpovice locality is discussed. Based on the lithology and studied fossil associations, it is assumed that a dysoxic environment with episodic currents prevailed in the Ejpovice locality. The fauna is species-depleted and taxa typical of the Dobrotivá Formation are rare. The fauna is mainly allochtonous and most of the organisms are considered as postmortal accumulations in this study. Key words:...

1 Abstract In recent years, the term small carbonaceous fossils (SCFs) has been established to accomodate fragile organic-walled fossils of micro- to mesoscopic size that are usually extracted by means of the 'low-manipulation HF extraction' method. This method has so far only been utilized by several authors and no reports have been published on the usage of the method on samples from the Barrandian area. To test the applicability of the method, samples from the Barrandian area were processed. The samples came from eleven localities representing six stratigraphic units (Paseky Shale, Jince Formation, Letná Formation, Kosov Formation, Daleje Shale and Roblín Member). All the units have been studied before by 'standard' methods of palynological processing. Various previously unreported fossils are described, including wiwaxiid sclerites, putative chaetognath remains and acritarch clusters. Furthermore, it is discovered, that the 'low-manipulation HF extraction' can also be used for extraction of originally calcareous fossils. The pilot study provides a further proof that the 'low-manipulation HF extraction' is a useful tool with the potential to significantly expand our knowledge of fossil assemblages. Key words: Small carbonaceous fossils, Cambrian, Ordovician, Devonian, Barrandian area

The Swan Peak Formation in southeastern Idaho and north-central Utah is a sedimentary unit consisting of orthoquartzite, sandstone, siltite, shale, and limestone. The formation is divisible into three members, and the lower two members each are divisible into two informal lithologic subunits. The lower member consists of a lower subunit of gray, calcareous sandy siltite composed of subangular to subrounded quartz grains cemented by quartz overgrowths, calcite, or iron oxide, and an upper subunit of black shale with minor interbedded silty quartzose sandstone and biomicrite (limestone). The middle member consists of a lower subunit of interbedded pale green shale and yellowish brown silty orthoquartzite and an upper subunit of purple orthoquartzite. The brown orthoquartzite consists of well-sorted, well-rounded very fine sand- to silt-sized quartz grains cemented by quartz overgrowths which are in optical continuity with the grains they surround. The purple orthoquartzite consists of wellsorted, well-rounded, very fine to medium sand-sized quartz grains cemented by quartz overgrowths and hematite. Hematite gives the rock its purple color. gydroxylapatite is locally abundant. The upper member is an orthoquartzite consisting of very fine to medium sand-sized, well-sorted, well-rounded quartz grains cemented by quartz overgrowths. The gastropod Murchisonia (Hormotoma) sp., the first body fossil found in the upper member, is reported. Previous work has shown that the upper member of the Swan Peak Formation and the Eureka Quartzite are similar in lithology, stratigraphy, and trace fossils. The Eureka Quartzite in the Newfoundland Range is a very fine to medium sand-sized, well-sorted, well-rounded orthoquartzite cemented predominantly by quartz overgrowths, locally by dolomite. The petrographic similarities of the two units, shown in the present study, strengthens their proposed correlation. High percentages of well rounded, polycrystalline and undulatory extinction quartz show that source areas for the Eureka Quartzite and Swan Peak Formation probably were immature sandstones or quartzites of Cambrian or Precambrian age, and./or exposed igneous or metamorphic rocks. The source for most of the sand probably was the Northwest Montana Uplift, although local sources along the Uinta Uplift undoubtedly played a minor role in supplying hydroxylapatite to the middle member and fine-grained elastics to the lower member.

The Kinnikinic Formation of central Idaho is a sedimentary unit consisting principally of orthoquartzite. From its maximum measured thickness of 2285 feet in the central Lemhi Range near Gilmore, Idaho, it thins westward to 376 feet at the type section and southward to 326 feet near Arco, Idaho. Northeast of the Lemhi Range it occurs only as erosional remnants, due to pre-Devonian erosion. Both the lower and upper contacts of the Kinnikinic Formation are disconformable. The Kinnikinic Formation is light colored, predominately fine to medium grained, thin to medium bedded, and largely cemented by silica overgrowths. Some metamorphic recrystallization has occurred locally. Although parallel laminae and structureless beds predominate within primarily parallel bedding, omikron-type (underwater dune) cross-laminae are locally abundant. The sediments are moderately sorted to well sorted and both positively and negatively skewed. Cumulative-frequency probability curves illustrate traction, "saltation," and "suspension" populations; some thin sections indicate two "saltation" populations. An open-marine, shallow-shelfal environment influenced by high-energy (tidal?) currents is postulated for deposition of the Kinnikinic Formation on the basis of the lithlogic uniformity, lateral extent, sedimentary structure, trace fossils, and paleogeographic setting. The Swan Peak Formation of southeastern Idaho and north-central Utah is divisible into a lower member of dark gray shale and quartz silitite, a middle member of brown orthoquartzite and light-colored shale, and an upper member of white orthoquartzite. Correlation of the white, fine- to medium-grained quartzite in the Raft River Range with the Ordovician Eureka Quartzite, considered probable by Compton (1972), is here accepted. The relatively thin nature of the Eureka Quartzite in this area reflects lesser sedimentation rates relative to areas farther south and/ or post-depositional erosion. The Dayley Creek Quartzite of Armstrong (1968) in the Albion Range is complexly faulted; as mapped, all or most of it probably is not correlative with the Kinnikinic Formation. Quartzites in the lower thrust plate of the Phi Kappa Formation in central Idaho are not environmental equivalents of the Kinnikinic Formation to the east, even though they apparently are approximately time equivalent (Churkin, 1963a, pp. 1612-1615). Middle Ordovician, shallow-shelfal orthoquartzit.es (Kinnikinic Formation, upper member of the Swan Peak Formation, Eureka Quartzite, and Mount Wilson Quartzite of southern Canada) are considered to be one originally continuous genetic unit, based on age determinations of overlying and underlying units, disconformable lower and upper contacts, close physical resemblances, and the high probability they were principally derived from the same source area, possibly Cambrian sandstones in the Peace River-Athabasca Arch area of northern Alberta, Canada. The shelfal environment of the Middle Ordovician Cordilleran miogeosyncline can be divided into at least five major, distinctly separated, basins of deposition: (1) Alberta-British Columbia Basin; (2) Central Idaho Basin; (3} Southeastern Idaho Basin (herein proposed); (4) Northeastern Nevada Basin; and (5) Ibex Basin. Anomalously high percentages of undulatory quartz grains in Middle Ordovician orthoquartzites of the Cordilleran miogeosynclinal shelf are highly suggestive of straining in situ and are probably related to post-depositional conditions ranging from purely tectonic to intricate combinations of tectonic and nontectonic events.

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