Abstract Conodont biofacies of the Lublin and Łysogóry–Radom basins in SE Poland have been analysed in five cored borehole sections in a narrow interval of the middle Givetian Polygnathus ansatus Zone, corresponding to the global Taghanic transgression. Assemblages exhibiting various proportions of dominant genera, Icriodus (I) and Polygnathus (P), as well as particular P species and a few accessory taxa, reflect both temporal transgression dynamics and lateral facies changes. The latter comprise transition from a brackish lagoon with intermittent open-marine influence, to a carbonate shoal and offshore marly shelf, generally characterized by P–I biofacies, but with a varying proportion of constituent genera and polygnathid species. Comparison of the Polish record with stratigraphically well-constrained, quantitative biofacies evidence worldwide allowed the construction of a 2D nearshore–offshore model for the Euramerican epicontinental faunas connected with Taghanic transgressive facies. The I/P ratio has a diagnostic value for specific sub-environments (very nearshore/shallow-water and drowned platform) but for other settings the Polygnathus ansatus to Polygnathus linguiformis ratio appears more useful. The Moroccan faunas display specific biofacies patterns tentatively explained by different climatic conditions. The conodont biofacies concept has a limited application for palaeogeographically isolated settings, including pelagic-oceanic areas of microcontinents or submarine rises. In other cases (Eastern Australia), palaeobiogeographical bias precludes direct comparisons with the Euramerican model.

Abstract Eifelian dolomites in the Zachełmie Quarry exhibit metre-scale depositional cyclicity, both in the lower, lagoonal part of the section and in the upper, shallow subtidal portion. Magnetic properties were studied in 30 samples (at c. 1 m intervals), including magnetic susceptibility (MS) and anhysteretic and isothermal remanent magnetization. The rock magnetic parameters are compared with the results of thin-section study and elemental chemistry. The forcing factors driving the MS pattern are identified. The MS signal is mostly related to a finely dispersed hematite, controlled by terrigenous input. Magnetite plays a subordinate role and it is confined to less terrigenous horizons relatively enriched in uranium and phosphorus. Results of high-resolution ( c. 8 cm intervals) MS field measurements show a good correlation with depositional shallowing-upwards cycles, especially in the lagoonal part of the section, where variations of rock magnetic properties and geochemical (redox and productivity) indices are very small. High MS values occur in the bottom part of the cycles and they decrease upwards. Time-series analyses of the MS signal reveal the dominance of c. 1.7 m cycles, grouped into c. 10 m bundles. The former cycles probably reflect precession-driven changes in monsoonal intensity, whereas the latter may have been controlled by 100 kyr eccentricity.

Abstract The term ‘Devonian’ was first used in the 1830s to describe a succession of rocks in Devonshire, a large county in SW England. The Devonian period is an interval of about 57 Ma in the middle part of the Palaeozoic with remarkable geological variety. It was influenced by active plate movements producing a wide range of environments and facies. The geosphere and biosphere were undergoing extraordinary changes during this period which can claim a remarkable number of biotic ‘firsts’, including the first appearance of vascular plants, ammonoids, insects and amphibians. A major radiation of fish took place and the Devonian has therefore been called ‘the age of fish’. The development of the earliest land floras, forests and soils on land areas changed the biosphere by transforming the terrestrial environment and linking it more closely with the aquatic realm. This influenced the evolution of tetrapods and their colonization of the land. The global climate switched from the hot greenhouse phase of the earlier Palaeozoic to the cold icehouse phase of the later Palaeozoic. This change was associated with one of the most important extinction phases of the Earth's history (the late-Frasnian biodiversity crisis). The greenhouse climate favoured the development of reef ecosystems dominated by rugose corals and stromatoporoids. They reached their acme in the Middle Devonian and disappeared in the late Frasnian, probably due to the global expansion of black, anoxic sediments on the shelves. Recent data suggest that the Frasnian crisis was triggered in large part by pulses of global