Peter Königshof

Paleoenvironment of an Early Devonian Land–Sea Transition: a Case Study from the Southern Margin of the Old Red Continent (Mosel Valley, Germany)

Abstract An interdisciplinary approach was used to investigate the facies and paleogeography of the Lower Devonian sedimentary sequence of the Alken quarry, Mosel Valley, Germany. This 87-m-thick sequence consists of stratified sandstones and sandy shales of the Nellenköpfchen Formation (uppermost Lower Emsian). Previous interpretations of the depositional environment include terrestrial, deltaic, and shallow-marine settings. Two distinct fossiliferous units contain abundant terrestrial plant remains and a diverse mixed terrestrial to marine fauna. Physical sedimentary structures are common throughout, whereas bioturbation is restricted mostly to the fossiliferous intervals. Erosional surfaces frequently separate the beds. Aside from ripple cross-stratification and parallel bedding, longitudinal inclined stratification is most common. Channel-fill structures are less frequent. Scour-and-fill structures exhibit marked disconformities of irregular shape on a smaller scale (dm). Mud-pebble lags at the base of laterally prograding cross-bedded layers, scour-and-fill structures, and drainage rills characterize the upper part of the section. Desiccation cracks, wind-induced striation, and water-level marks occur more sporadically in the exposure. The sedimentary structures and the paleontological information indicate a marine to brackish depositional environment that frequently was emergent. The presence of conspicuous channel-related structures reflects intertidal conditions along the coastal region of a presumed Hunsrück Island/Archipelago. Lagoons and estuaries were bordered by extended tidal flats, in which migrating channels frequently occurred. Terrestrial plant remains, however, indicate a position at the land/sea interface, which was characterized by a complex configuration of different environments. The accumulation of concentrated plant material may have been related to distinct meteorological events such as hurricanes.

Shallow-water facies setting around the Kačák Event: a multidisciplinary approach

Abstract In the Eifel area (western Rheinisches Schiefergebirge), a shallow- to deep-subtidal sequence of mixed carbonates and siltstones around the Kačák Event Interval close to the Eifelian–Givetian stage boundary was studied. An overall transgressive trend is inferred by the microfacies evolution. The stratigraphic variations of magnetic susceptibility in carbonates and in shale intervals show an overall decreasing evolution towards the top, which fits well with the transgressive trend. In addition, carbon and oxygen isotopes, and major, trace and rare earth element (REE) analysis have been used to get a better understanding of palaeoenvironmental variations in a shallow-water realm in the late Eifelian (kockelianus and ensensis conodont biozones): for example, the δ13C excursion and Ce anomaly are interpreted to be the local representation of the beginning of the Kačák Event Interval, which is also consistent with the stratigraphy and microfacies analyses.

Palaeoenvironmental study of the Palaeotethys Ocean: the Givetian-Frasnian boundary of a shallow-marine environment using combined facies analysis and geochemistry (Zefreh Section/Central Iran)

The Zefreh section in central Iran represents a carbonate ramp succession with a general shallow-marine palaeoenvironment. This section represents most of the Bahram Formation (Givetian to at least Middle falsiovalis Zone) and consists of a very heterogeneous succession of medium- to coarse-grained sandstones, skeletal pack- to grainstones with local biostromes, massive or laminated dolostones, and shales. Microfacies analysis allowed the discrimination of 12 microfacies reflecting supratidal to open marine palaeoenvironments. The shallow-marine environment was investigated using facies analysis and geochemical proxies. Redox conditions in the Zefreh section appear to be primarily oxic and support the facies and sedimentological results. The provenance of the Zefreh sediments using La, Sc, Zr, and Th indicates that they are most likely derived from continental arc volcanics which is consistent with the preliminary tectonic interpretations. Conodonts and brachiopods were used for establishing the biostratigraphical framework. The lack of important zonal index taxa of the widely applied conodont standard zonation requires the application of an alternative shallow-marine conodont zonation. Based on conodont and brachiopod data, the Zefreh section covers sediments ranging from the upper Givetian to lower Frasnian.

Middle Devonian (Givetian) conodonts from the northern margin of Gondwana (Soh and Natanz regions, north-west Isfahan, Central Iran): biostratigraphy and palaeoenvironmental implications

Four sections of mainly Middle Devonian (Givetian) shallow-marine rocks at the northern margin of Gondwana (Central Iran) were investigated with a special focus on the Bahram Formation, as the stratigraphic range of the Bahram Formation is uncertain and still under discussion. Generally, the Bahram Formation is discontinuously underlain by the Lower Devonian Padeha Formation and disconformably overlain by the Permian Jamal Formation. Conodont communities from the four sections in the Soh area (Najhaf and Neqeleh sections) and the Natanz area (Varcamar and North Tar sections) were investigated. The most widely applied conodont standard zonation of the Upper Givetian contain taxa characteristic of deeper shelf facies whereas conodont fauna of the investigated sections mainly show affinities to shallow-marine environments. Shallow-water conodont associations corresponding to the expansus Zone and subterminus Zone are described from Central Iran for the first time, whereas the vast majority of icriodontid and polygnathid faunas were reported from shallow-marine carbonates around Laurussia (e.g. North America, and Europe). Thirty-six species and subspecies were assigned to five genera (Ancyrodella, Bipennatus, Icriodus, Polygnathus and Pandorinellina). The sedimentological record is characterised by remarkable lateral facies changes, but in the upper part of the Givetian, a general transgressive trend is obvious due to the dominance of limestones and small biostromes.

A Late Devonian (Frasnian) bryozoan fauna from central Iran

A bryozoan fauna from the Late Devonian (Frasnian) of the Bahram Formation of the Zefreh section in central Iran contains four species: three trepostomes and one rhabdomesine cryptostome. Two species are new: the trepostome Coeloclemis zefrehensis sp. nov. and the rhabdomesine cryptostome Euthyrhombopora tenuis sp. nov. The trepostome species Cyphotrypa definita Morozova, 1960 and Anomalotoechus ramosus Morozova, 1960 were recorded previously from the Upper Devonian (Frasnian) of the Kuznets Basin. The genera Coeloclemis and Euthyrhombo-pora are recorded from the Devonian for the first time. The fauna is dominated by the erect ramose Euthyrhombopora tenuis sp. nov., with rare occurrences of the massive Cyphotrypa definita Morozova, 1960. The bryozoans indicate low to moderate water energy environment of middle to outer ramp position.

Devonian events: examples from the eastern Palaeotethys (Si Phai section, NE Vietnam)

Recent study of Middle to Upper Devonian deposits in the Dong Van area, northeast Vietnam, has revealed new, more detailed information of both the stratigraphic record of the Si Phai section and global Devonian bioevents. Four possible equivalents of well-known Devonian events of different magnitude were found in Vietnam, an area which is underrepresented in that respect: the (?) Kačák Event, the (?)pumilio Events, the late Middle Givetian Taghanic Event and the Frasnian/Famennian Kellwasser Event. The stratigraphic framework of the Si Phai section allows us to recognise and assess the timing of global Devonian bioevents in Vietnam even though the section is not continuous. An overview of the sedimentological development of the Si Phai section is discussed briefly where carbonates in the section are composed of argillaceous limestones suggesting relatively deep, off-shore conditions. Due to the facies setting, the macrofauna is generally rare and the conodont record is likewise limited in some parts. Nevertheless, it is possible to pinpoint some global event intervals for the first time in Vietnam.

Increasing knowledge on biodiversity patterns and climate changes in Earth’s history by international cooperation: introduction to the proceedings IGCP 596/SDS Meeting Brussels (2015)

Current and future climate change is a global issue that can be addressed only by international cooperation. Climate modelling is a useful tool for a better understanding of climatological processes but is significantly enhanced by the knowledge of organisms and changing biodiversity in deep time. The midPalaeozoic was a time of rapid, fundamental change in Earth’s climate systems resulting in significant sea-level fluctuations and catastrophic changes in ocean chemistry producing global oceanic anoxia. Ecosystems were severely impacted by a series of mass extinctions and ecological perturbations (e.g. virtual loss of reef ecosystems) that fundamentally changed the trajectory of life on Earth. Fluctuations in the physical environment during these biotic crises are usually (but not always) revealed in the sedimentary record as black shales and as geochemical excursions in Devonian sediments. Regardless of methodology, all the analyses conclude that the midPalaeozoic was a time of multiple anoxic events and associated biotic crises that spanned many millions of years. Thus, an understanding of the major abiotic and biotic factors that shaped our planet and its ecosystems in the past is essential to the understanding of natural processes and the effects of human-induced global change at present and for forecasting possible future developments. In other words, knowledge on past systems is essential if we want to model future climate with confidence. Furthermore, it seems important to increase knowledge in areas and countries which are underrepresented in terms of climate change and event research in the midPalaeozoic. In that respect, IGCP projects, supported by IUGS and UNESCO, serve as door-opener in many countries. In the framework of the IGCP 596, we visited many countries in several continents. Fieldwork was often difficult and a real challenge (Figs. 1 and 2). Regardless of methodology such as geochemistry, geophysics or facies analysis, the detailed knowledge of fossils is crucial. Thus, alpha taxonomy remains the fundamental basis for any investigation of the evolution of life on Earth, including fields of phylogenetic analysis, historical biodiversity, biogeography and biostratigraphy. Today, there is a lack of awareness of the fundamental importance of systematics and/or biostratigraphy. Taxonomy is crucial to high-resolution biostratigraphy. The ongoing decline in research and expertise in that special field in palaeontology jeopardises future macroevolutionary and biostratigraphic studies. Thus the collabora t ion between IGCP 596 and the in terna t ional Subcommission on Devonian Stratigraphy (SDS) also tried to involve specialists working on different fossil groups to the extent possible. In that sense, many progress reports related to the revision and erection of new taxa were linked with the Palaeobiology Database (http://paleodb.org/). This article is a contribution to the special issue ‘Climate change and biodiversity patterns in the mid-Palaeozoic’

Late Silurian and Devonian ostracods of the Istanbul Zone (Western Pontides) and the Taurides: palaeogeographical implications

Non-metamorphic Palaeozoic sedimentary successions without major breaks exist in the Istanbul Zone of the Western Pontides (northern Turkey) and in the Taurides (southern Turkey). Based on different proxies, a Gondwanan affinity has been determined for the Taurides; however, the palaeogeographical position of the Istanbul Zone is still controversial. The aim of this paper is to discuss possible contributions of late Silurian and Devonian ostracods to the palaeogeographical assignment of the Western Pontides (Istanbul Zone). Furthermore, ostracods of the Taurides have also been evaluated in terms of the palaeogeographical setting of this terrane. Late Silurian ostracods of the Istanbul Zone (Western Pontides) show close similarities at the species level with the assemblage from the upper Silurian (Ludlow) rocks of Baltica. This Laurussian affinity indicates a palaeogeographical setting to the north of the Rheic Ocean for the Pontides during the late Silurian. The Devonian ostracod assemblages of both the Taurides and the Istanbul Zone have an affinity to both Laurussia and Gondwana. Therefore, a faunal link should exist during this long period between Laurussia and Gondwana. The faunal link between the two palaeocontinents can be explained on the one hand by a narrow ocean with shallow pathways. On the other hand, a wider ocean with long-shore currents, with broad and shallow shelf areas and/or islands functioning as stepping stones would also allow a faunal link for benthic ostracods.

Conodont biostratigraphy of the Kesheh and Dizlu sections, and the age range of the Bahram Formation in central Iran

Conodont fauna from the Kesheh and Dizlu sections in the North Isfahan province were investigated. Shallow-water and/or near-shore conodonts, mainly belonging to the icriodid–polygnathid biofacies, dominate the conodont fauna. Due to the depositional setting which is characterised by predominantly shallow-water palaeoenvironments and the lack of some important zonal index taxa (e.g. Palmatolepis species), a precise conodont biostratigraphy is difficult to establish. The Kesheh section covers sediments ranging from the Givetian hermanni Zone to disparilis Zone whereas in the Dizlu section, the ranges of Middle triangularis to Uppermost crepida, the marginifera to Upper trachytera, and the Lower and Middle expansa Zones indicate a Famennian age. The stratigraphic range of the Bahram Formation is discussed, and according to literature and new conodont data presented herein, it is likely that the age of the Bahram Formation in central Iran has a stratigraphical range from the Givetian (hermanni Zone) to the late Famennian (Middle expansa Zone).

New Middle Devonian conodont data from the Dong Van area, NE Vietnam (South China Terrane)

Middle Devonian conodonts from the Si Phai section in NE Vietnam are described. The section ranges from the Middle Devonian ensensis to timorensis conodont zones to the Late Devonian rhomboidea conodont Zone. A rich overall assemblage is described, including 27 taxa of species or subspecies rank and 11 taxa described in an open nomenclature. Among the dominant Polygnathus forms, four new taxa are described: Polygnathus linguiformis saharicus subsp. nov., Polygnathus linguiformis vietnamicus subsp. nov., Polygnathus rhenanus siphai subsp. nov., and Polygnathus xylus bacbo subsp. nov. Conodont assemblages are attributed to polygnathid, polygnathid-klapperinid, and klapperinid conodont biofacies representing hemipelagic to pelagic environments. The klapperinid biofacies, unreported in the previous literature, are here attributed to offshore areas of the external shelf. The taxonomic compositions of the studied conodont assemblages, as well as their CAI characteristics (CAI 4–5), suggest a palaeogeographic affinity of the studied strata to the Chinese Devonian Guangxi Basin, and the South China Terrane in general. Furthermore, the conodont biofacies and the palaeogeographic distribution of the fauna are discussed.