ALBERT

Beschreibung: The Givetian pelagic and dysoxic outer shelf facies of the Dra Valley (SW Morocco) yielded as minor benthic faunal elements a number of stringocephalid and uncitid brachiopods that allow a precise correlation of these marker brachiopods with the regional, detailed goniatite zonation. In a reverse situation, the predominant neritic shallow-water succession of the Bergisch Gladbach area (Rhenish Massif, Germany), which is characterized by a detailed succession of stringocephalids and Uncites, has yielded rare and new Middle Givetian goniatite species. These findings allow, with some help of conodont data, neriticpelagic correlations within and between widely separated basins. New species are Tornoceras n. sp. from the Buchel Formation (with coloration remains), Trevoneites' paffrathensis n. sp. from the Lower Plattenkalk Formation, and Maenioceras heinorum n. sp. from the Hornstein Member. New material of stringocephalids and Uncites is described from the Dra Valley. The identical, well-defined range of Uncites (U.) gryphus gryphus in the lower to middle parts of the Middle Givetian of the Dra Valley and Rhenish Massif underscores the stratigraphical significance of this genus that was widely distributed in Europe, northern Gondwana, the Urals, and Central and Eastern Asia.

Beschreibung: Two pelagic successions near Ain Jemaa (Oulmes region, Moroccan Meseta) are dated by conodonts and ammonoids and provide new data on the discontinuous Middle to Upper Famennian faunal and facies evolution in the region. Upper Devonian shales and nodular limestones are assigned to the new Bou Gzem Formation, which is subdivided into three members. The Upper Member consists of black shales that are correlated with the globally widespread, transgressive black shale interval of the Hangenberg Event. The overlying quartzites are interpreted as prodeltaic deposits and assigned to the new Taarraft Formation that probably correlate with the major regressive phase of the Hangenberg Event. Contemporaneous ( Strunian') coarse siliciclastics have a wide distribution in different structural units of the Meseta. Both studied sections display a long sedimentary gap but of different extent at the base of the black shales. Comparison with other regions of Hercynian Morocco suggest an influence of Eohercynian tectonics on sedimentation, leading to extreme condensation and/or non-deposition, whilst other Meseta areas show evidence of contemporaneous reworking on uplifted structural highs and massive shedding of mass flows, conglomerates and turbidites into adjacent pelagic basins. Data from Oulmes and other Meseta regions suggest a timing of tectophases as early Middle Famennian (starting within the marginifera Zone) and Upper Famennian (starting within the Middle expansa Zone), interrupted by transgressive pulses of the global Annulata and Dasberg Events.

Beschreibung: Emsian to Frasnian crinoids are described from pelagic facies of the eastern part of the Dra Valley (Tata area), western Anti-Atlas Mountains, southern Morocco. The crinoids show only minor relationship with previously described crinoids from the Tafilalt and Ma'der areas of the eastern Anti-Atlas. The differences are judged to reflect the different environments of these areas. The Dra Valley hexacrinids show greater affinity with European faunas, whereas the amabilicrinids show greater affinity with North American taxa. New taxa described are Hexacrinites chenae sp. nov., Dracrinus crenulatus gen. and sp. nov., Coquinacrinus revimentus gen. and sp. nov, and Embolocrinus quadruus gen. and sp. nov.

Beschreibung: A review of the literature shows that the Famennian global Annulata Event(s) can be recognized as a transgressive, often hypoxic and eutrophic, interval that interrupts an overall regressive eustatic trend in more than 40 regions of North America, Europe, North Africa, Asia and Australia. According to differences in palaeogeography, sedimentology and biota, these occurrences are assigned to 10 event settings. The first detailed data on facies, ammonoid and conodont faunas are presented for the Rheris Basin of the eastern Anti-Atlas (southern Morocco) and compared with previously studied sections of the adjacent Tafilalt Platform, Tafilalt Basin and Maider Basin. The rather argillaceous succession at El Gara resembles the Tafilalt Basin (Hassi Nebech section) in its lack of black shales/limestones and similar ammonoid and conodont assemblages. However, the Sulcoclymenia sulcata Zone (Upper Devonian III-C2) below the Annulata Events contains ammonoid taxa that are unique for all of the Anti-Atlas and North Africa: Protornoceras ornatum Dybczynski, 1913, Genuclymenia aff. angelini (Wedekind, 1908), Protactoclymenia aff. implana (Czarnocki, 1989) and ? Pleuroclymenia sp. juv. The first regional record of the marker conodont Pseudopolygnathus granulosus Ziegler, 1962 also distinguishes the pre-event assemblage. As in many other regions, there is a major decline in ammonoids well before the Lower Annulata Event, which suggests an episode of extreme oligotrophy. Both Annulata Events at El Gara are whitish-weathered marly shales with only small specimens of Platyclymenia and Prionoceras ( sensu lato ), which are also typical for the annulata Zone (UD IV-A) of other Tafilalt sections, but benthonic organisms are nearly absent. This suggests local low-oxygen conditions, but only a moderate production of organic carbon, insufficient for black shale formation, unlike many German sections or in the Maider Basin (section Mrakib). The latter region represents a deeper shelf basin that had much higher productivity and a unique ‘ Gundolficeras – Erfoudites – Protactoclymenia – Stenoclymenia – Guerichia biofacies’ of the Lower Annulata Shale. The upper part of the annulata Zone at El Gara is characterized by Platyclymenia ( Platyclymenia ) levata n. sp. Other new taxa of the same zone in the Anti-Atlas are Posttornoceras ascendens n. sp. and Stenoclymenia rectangula n. sp. Whilst the ammonoid faunal overturn between UD III-C and UD IV-A was severe, the strong reduction in conodont diversity with the two Annulata Events was mostly (apart from two taxa) a palaeoecologically triggered, only episodic, feature. The comparison of the various Anti-Atlas Annulata Event beds and assemblages enables the distinction of event biofacies types, which reflect local differences of bathymetry, trophic conditions and seafloor ventilation.

Beschreibung: Extract The face of Planet Earth has changed significantly through geological time. Dynamic processes active today, such as plate tectonics and climate change, have shaped the Earth's surface and impacted biodiversity patterns from the beginning. Organisms, on the other hand, have the capacity to significantly alter Earth's hydrological and geochemical cycles, its atmosphere and climate, sediments, and even hard rocks deep down under the surface. Abiotic–biotic interactions characterize Earth's system history and, together with biotic competition and food webs, were the main trigger of evolutionary change, innovations and biodiversity fluctuations. Within the Palaeozoic, the Devonian was an especially interesting time interval as it was characterized by the ‘mid-Paleozoic predator revolution’ (Signor & Brett 1984; Brett 2003) and the related ‘nekton revolution’ (Klug et al. 2010), characterized by the blooms of free-swimming cephalopods, including the oldest ammonoids, and fish groups (e.g. toothed sharks and giant placoderms), the rise of more advanced vertebrates, including the oldest tetrapods (e.g. Blieck et al. 2007, 2010; Niedzwiedzki et al. 2010), the most extensive reef complexes of the Phanerozoic (e.g. Kiessling 2008), and the ‘greening of land’ by the diversification and spread of land plants, including the oldest forests (e.g. Stein et al. 2012; Giesen & Berry 2013), which resulted in new soil types and changing weathering. ... This 250-word extract was created in the absence of an abstract.

Beschreibung: The global Hangenberg Crisis near the Devonian–Carboniferous boundary (DCB) represents a mass extinction that is of the same scale as the so-called ‘Big Five’ first-order Phanerozoic events. It played an important role in the evolution of many faunal groups and destroyed complete ecosystems but affected marine and terrestrial environments at slightly different times within a short time span of c. 100–300 kyr. The lower crisis interval in the uppermost Famennian started as a prelude with a minor eustatic sea-level fall, followed rather abruptly by pantropically widespread black shale deposition (Hangenberg Black Shale and equivalents). This transgressive and hypoxic/anoxic phase coincided with a global carbonate crisis and perturbation of the global carbon cycle as evidenced by a distinctive positive carbon isotope excursion, probably as a consequence of climate/salinity-driven oceanic overturns and outer-shelf eutrophication. It is the main extinction level for marine biota, especially for ammonoids, trilobites, conodonts, stromatoporoids, corals, some sharks, and deeper-water ostracodes, but probably also for placoderms, chitinozoans and early tetrapods. Extinction rates were lower for brachiopods, neritic ostracodes, bryozoans and echinoderms. Extinction patterns were similar in widely separate basins of the western and eastern Prototethys, while a contemporaneous marine macrofauna record from high latitudes is missing altogether. The middle crisis interval is characterized by a gradual but major eustatic sea-level fall, probably in the scale of more than 100 m, that caused the progradation of shallow-water siliciclastics (Hangenberg Sandstone and equivalents) and produced widespread unconformities due to reworking and non-deposition. The glacio-eustatic origin of this global regression is proven by miospore correlation with widespread diamictites of South America and South and North Africa, and by the evidence for significant tropical mountain glaciers in eastern North America. This isolated and short-lived plunge from global greenhouse into icehouse conditions may follow the significant drawdown of atmospheric CO 2 levels due to the prior massive burial of organic carbon during the global deposition of black shales. Increased carbon recycling by intensified terrestrial erosion in combination with the arrested burial of carbonates may have led to a gradual rise of CO 2 levels, re-warming, and a parallel increase in the influx of land-derived nutrients. The upper crisis interval in the uppermost Famennian is characterized by initial post-glacial transgression and a second global carbon isotope spike, as well as by opportunistic faunal blooms and the early re-radiation of several fossil groups. Minor reworking events and unconformities give evidence for continuing smaller-scale oscillations of sea-level and palaeoclimate. These may explain the terrestrial floral change near the Famennian–Tournaisian boundary and contemporaneous, evolutionarily highly significant extinctions of survivors of the main crisis. Still poorly understood small-scale events wiped out the last clymeniid ammonoids, phacopid trilobites, placoderms and some widespread brachiopod and foraminiferan groups. The post-crisis interval in the lower Tournaisian is marked by continuing eustatic rise (e.g. flooding of the Old Red Continent), and significant radiations in a renewed greenhouse time. But the recovery had not yet reached the pre-crisis level when it was suddenly interrupted by the global, second-order Lower Alum Shale Event at the base of the middle Tournaisian.

Beschreibung: Chrono-, litho- and biostratigraphy across the Devonian–Carboniferous transition are reviewed to provide a precise time framework for the global Hangenberg Crisis and for the current search for a revised basal Carboniferous Global Stratotype Section and Point (GSSP). The outer shelf deposits of the Rhenish Massif (Germany) form a lithological standard. Pre- (main Wocklum Limestone), lower (top Wocklum Limestone/Drewer Sandstone to Hangenberg Black Shale), middle (Hangenberg Shale/Sandstone), upper (Stockum Limestone), and post-crisis (Hangenberg Limestone) deposits are defined. Combined with the conodont, ammonoid and miospore zonations and eustatic trends, this succession can be correlated internationally. The contemporaneous successions of the Ardennes serve as a reference for shallow shelf settings. The positive and negative aspects of five options for a redefined Devonian–Carboniferous boundary level are discussed: (1) base of the black shale (main extinction level, base of Bispathodus costatus–Protognathodus kockeli Interregnum and LN Zone), (2) sequence boundary (widespread unconformities) or glacial and regressive peak (base of Hangenberg Sandstone), (3) base of the kockeli Zone and of initial postglacial transgression (base of lower Stockum Limestone), (4) entry of Siphonodella ( Eosiphonodella ) sulcata (base of upper Stockum Limestone), and (5) base of post-crisis interval (base of Hangenberg Limestone), at approximately the poorly correlated current GSSP level. Due to homonymy, Siphonodella ( Siphonodella ) hassi Ji, 1985 is renamed as Siphonodella ( Siphonodella ) jii nom. nov. Consequently, the mid-lower Tournaisian S. ( S .) hassi Zone (previous Upper S. ( S. ) duplicata Zone) becomes the S. ( S. ) jii Zone.