Famennian

The Upper Devonian Palliser Formation and its subsurface equivalent Wabamun Formation of western Canada comprise areally and volumetrically one of the largest epeiric carbonate platforms on Earth, covering some 600,000 km2 and reaching 600 m in thickness. Of Famennian age, these monotonous rocks formed in the aftermath of one of the great Paleozoic mass extinction events. Inboard of a ramp-like margin of gentle inclination (<0.5°), the platform shallowed imperceptibly eastward, eventually becoming locally evaporitic in interior areas. The platform is thus characterized by a series of broad facies belts reflecting its relative shallowness and enormous width. Limestones cropping out in the southern and central Rocky Mountains represent mainly the outer and middle parts of the platform. These regions never developed facies cyclicity and the platform remained submerged. The Upper Devonian Palliser Formation and its subsurface equivalent Wabamun Formation of western Canada comprise areally and volumetrically one of the largest epeiric carbonate platforms on Earth, covering some 600,000 km2 and reaching 600 m in thickness. Of Famennian age, these monotonous rocks formed in the aftermath of one of the great Paleozoic mass extinction events. Inboard of a ramp-like margin of gentle inclination (<0.5°), the platform shallowed imperceptibly eastward, eventually becoming locally evaporitic in interior areas. The platform is thus characterized by a series of broad facies belts reflecting its relative shallowness and enormous width. Limestones cropping out in the southern and central Rocky Mountains represent mainly the outer and middle parts of the platform. These regions never developed facies cyclicity and the platform remained submerged. Calcimudstones and peloidal wackestones overwhelmingly dominate with significant proportions of intraclasts, aggregates, dasycladalean calcareous algae, crinoid ossicles and minor amounts of brachiopods, gastropods, ostracodes and sponge spicules; bioturbation was ubiquitous and multi- generational. The shallow seafloor was flat and virtually featureless, with widespread meadows of algae and crinoids plus a few areas of low-relief stromatoporoidal patch reefs. In this storm-dominated system, the sediment surface of varying stiffness was swept and scoured frequently, leaving pack- to grainstones composed of rounded intraclasts and sediment-filled burrows. The abundance of algae and dominantly micritized aspect of crinoid ossicles suggest that the platform was mesotrophic, receiving elevated nutrient supply from the Ellesmerian orogen on the northern side of the craton.
Although superficially uniform and ‘layer-cake’ in aspect, subtle compositional changes show that the platform exhibits four, hitherto unrecognized, long-term transgressive– regressive sequences, culminating in the demise of carbonate sedimentation and burial by nearly craton-wide black shales. Eustatic sea level and, more importantly, subsidence rate fluctuated during these sequences, with the third sequence characterized by subaerial exposure of the proximal region. Thicknesses calibrated to conodont biozones indicate that the marginal ramp had the greatest accumulation rate, although without any dramatic alteration of paleotopography.  The ability of carbonate production to keep a balance with subsidence and eustasy over ~10 million years and hundreds of metres of strata yet not display in peritidal cycles is a characteristic shared by many other large platforms. It may reflect insufficient carbonate production rates, a higher energy regime, and off-platform sediment redeposition, coupled with stable mesotrophic conditions.

Brachiopods (Productida [except Chonetidina], Orthida, Athyridida, Spiriferida [Adolfiidae, Reticulariidae, Ambocoeliidae, Thomasariidae], and Spiriferinida) recovered in the interval, in terms of the standard conodont zonation, between the Palmatolepis hassi and P. triangularis zones (Late Middle Frasnian to Early Famennian) in the Namur-Dinant Basin (Belgium) are described. The orders and suborders investigated include 32 species: 21 are described in open nomenclature, seven are previously known, four are new of which three are assigned to previously known genera: Aulacella aggeris n. sp., Dicamara plutonis n. sp., and Warrenella (Warrenella) aquaealbae n. sp. Th e fourth species belonging to a newly defined genus: Neptunathyris buxi n. gen., n. sp. A major brachiopod faunal change occurs at the top of the P. rhenana Zone in southern Belgium, with the disappearance of most existing species in parallel with the deterioration of the oxygenation conditions preceding the Upper Kelwasser Event. Only an impoverished fauna (Lingulida, Chonetidina, Rhynchonellida) has been collected in the P. linguiformis Zone. The recovery of the Famennian brachiopods after the end-Frasnian biotic crisis was rapid in the basal Famennian but, despite their great abundance, their diversity was relatively low. New cosmopolitan genera appeared at this time especially among the rhynchonellids, athyridids and spiriferids with new species of pre-existing orthid and orthotetid genera.

Southern Belgium is a classical area for the study of the Famennian sedimentary succession. Here are presented three localities providing an insight of the whole regressive Famennian with a particular view on the proximal-distal duality. The Rochefort section is one of the rare outcrop showing the Lower Famennian Famenne Formation which is particularly fossiliferous. The Limbourg quarry exposes the unique Middle Famennian Baelen reef from its microbialitic core to the crinoidal lateral facies. The quarry being partly undergroungit provides a unique three-dimensional view of the reef facies. The Tienne des Marteaux Quarry is a good example of proximal facies of the Belgian Famennian, with alluvial and fluvial deposits commonly rich in plant and vertebrate remains.

Petrophysical (gamma-ray spectrometry, magnetic susceptibility) and geochemical (X-ray fluorescence spectrometry and inorganic carbon isotope geochemistry) methods are used for stratigraphic correlations and palaeoenvironmental interpretations of the Devonian-Carboniferous boundary interval in the northern part of the Rheinisches Schiefergebirge, Germany. Sections at Oese, Oberrödinghausen and Drewer were studied in the stratigraphic range from the Famennian Upper expansa Zone to the Tournaisian Lower crenulata Zone. The Famennian Wocklum Limestone reveals distinctive cyclicity in the limestone and shale arrangement, whose primary origin has been supported by correlation with K/Al ratio changes. Lower-order K/Al cyclicity follow bundles of alternating layers. On the other hand, Zr/Al cyclicity is rather independent on facies and K/Al and duration of Zr/Al cycles was estimated to be 370 ka, which is close to 405 ka eccentricity. Correlations of the curve patterns of Computed Gamma Ray, U/ThGRS, bulk magnetic susceptibility, K/Al, Zr/Al, S, and Mn proxies have been employed for regional correlation. Our dataset confirms previous palaeoenvironmental interpretations of the Hangenberg Events and additionally provides information on gradual decrease in a bottom oxygenation just prior the events. Peaks in redox and palaeoproductivity proxies (U/Th, Cu+Ni+Zn+Pb) occur in the Hangenberg Black Shale in all studied sections. Although sedimentation of the Hangenberg Black Shale took place during the deepening step, the enhanced palaeoproductivity and hypoxia to anoxia were the main cause of its deposition. An interregional correlation of the Devonian-Carboniferous intervals from the northern Rhenish Massif, Moravian Karst and Carnic Alps was carried out and underlines the potential for further chronostratigraphic definitions.

Brachiopods of the orders Strophomenida, Orthotetida, and Athyridida from the late middle Frasnian–early Famennian interval (hassi to triangularis conodont zones) in the Namur-Dinant Basin (southeastern margin of Laurussia; southern Belgium) are described. Nine genera and subgenera represented by 12 species are recognized here. One new genus, Retrorstrophia, and one new species, Douvillina area, are erected. Crinisarina stainbrooki is proposed to solve the homonymy between C. reticulata (Gosselet, 1877) and Cleiothyridina reticulata Stainbrook, 1947, the type species of Crinisarina Cooper and Dutro, 1982. A lectotype is selected and illustrated for C. reticulata. A new name is also proposed for Athyris reticulata Chen and Xu, 2000, which is assigned here to Crinisarina: C. shashishanensis nom. nov. In southern Belgium, the last representatives of the families Douvillinidae and Leptostrophiidae (Strophomenida) are from the Upper rhenana Zone (late Frasnian). Athyridid brachiopods, especially the representatives of the subfamily Cleiothyridininae constituted a significant part of the early Famennian recovery faunas with spiriferids and rhynchonellids, just after the late Frasnian mass extinction.

After the late Frasnian extinctions, the rugose corals slowly recovered during the Lower and Middle Famennian (crepida
to marginifera conodont zones) in southern Belgium and northern France (Avesnois) (Namur–Dinant Basin). Six genera represented by seven species are recognized and described here; one species (Breviphrentis superstes) is new. The rugose coral fauna described herein includes small solitary forms belonging to the so-called Cyathaxonia fauna and is similar or very close to those previously described within the same stratigraphic interval in Australia, China and Germany. It also contains a large species belonging to the genus Breviphrentis
which was considered as extinct since the end of the Givetian (Middle Devonian) (“Lazarus taxon”). The tabulate corals from the Lower and Middle Famennian of this area, mainly represented by auloporids, are also briefly discussed. Rugosa only constituted a minor part of the fauna after the end-Frasnian crisis in the Namur–Dinant Basin contrary to the brachiopods, which were abundant and relatively diversified, and no rugose corals have been recovered from the early Lower Famennian (triangularis Zone). The first important Famennian coral radiation only took place during the Latest Famennian (Strunian).

Abundant trilobite remains were recovered from late mid−Famennian marlstones from various sites in Eastern Tafilalet, southeast Morocco. All belong to a single taxon previously identified as Cyrtosymbole (Waribole) prima. This taxon is designated the type species of Osmolskabole gen. nov. A redefinition of this species, including the description of newly discovered, disarticulated exuviae both in limestone and silicified state of preservation, is given. In particular, silicified sclerites of various sizes allow the first complete growth series of a cyrtosymboline proetid to be presented. The close morphological resemblance of its protaspid stages to known proetoid larvae emphasizes the homogeneity of the early ontogeny in this superfamily. The Famennian proetoid anaprotaspis is also of comparable size to that of other Devonian proetoid larvae. However, their size−range is much less than that observed in Carboniferous larvae. This suggests that the survival of proetoid trilobites at the Frasnian - Famennian Kellwasser crisis did not result from a modification of the developmental strategy, as it might have been the case at the terminal Devonian extinction event. Moreover, O. prima possesses a plectrum from the metaprotaspid to the mid meraspid periods. This implies that the natant hypostomal condition is not steadily acquired early in the ontogeny of the Proetida. Thus we preclude the use of this character in the diagnosis of this order.

The article presents new results of biostratigraphic and isotopic analyses for the Upper Famennian - Lower Tournaisian deep-water deposits of the Syvyu River section. Ostracode and conodont faunal changes, interpretation of lithological particularities and O and C isotopic variations enabled description of the boundary of the Systems, and identify stratigraphic equivalents of the Hangenberg Shale.

A new species of trilobite, Cyrtosymbole rectifrons, from Famennian marlstones in the south-eastern vicinity of Erfoud (Tafilalt, Morocco), is described. Silicified sclerites of various sizes allow the description of its late growth sequence, which demonstrates that some characteristic features of the Cyrtosymbolinae are acquired during late ontogeny. Precise examination of exceptionally well-preserved material enables reconstruction of the in situ  position of the adult hypostome, together with a reconsideration of its relation to the dorsal exoskeleton and its morphofunctional capacity for movement. The natant hypostomal condition inferred for C. rectifrons suggests that it is not always possible to deduce the nature of hypostomal attachment from the dorsal morphology alone.

Numerous silicified and calcareous sclerites of various sizes, recovered from the latest Famennian of Thuringia (Germany), allow the description of the first complete growth series of a blind proetoid trilobite: Drevermannia richteri. In addition, the partial ontogenetic development of Drevermannia antecurvata sp. nov. and undetermined species, Drevermannia sp. 1, are described. The proetoid anaprotaspides, associated with D. richteri, illustrate that a marked increase in larval size occurred prior to the terminal Devonian extinction event. Considering the homogeneity of larval size in older Devonian proetoids, it is interpreted as evidence that the developmental strategy of these trilobites was significantly modified. Though largely speculative, two alternative hypotheses are proposed to explain this modification. Finally, all three ontogenetic sequences show that ocular structures never develop externally in Drevermannia, but also illustrate that the development of optical nerves is not completely lost in this group. This suggests that blindness in the Drevermannia lineage followed a centripetal mode of eye reduction.

The cause of the Frasnian-Famennian boundary (FFB) biotic crisis, one of the " Big Five " Phanerozoic mass extinctions, remains poorly understood. Here, we generated a high-resolution uranium-isotope profile (δ 238 U) for a marine carbonate section at Baisha, South China, in order to document secular variation in mean global-ocean redox conditions and to compare its relationship to coeval changes in organic carbon burial fluxes (as proxied by δ 13 C carb) and global climate conditions. δ 238 U varied in a coordinated, mostly positive relationship with δ 13 C carb , indicating that expanded (reduced) oceanic anoxia was linked to lower (higher) productivity. This pattern is inconsistent with productivity control of redox conditions and suggests instead that both proxies responded to a common climatic forcing. We infer that climatic cooling (and glaciation during the Upper Kellwasser Horizon [UKH] event) led to better-ventilated oceanic conditions (higher δ 238 U) and greater productivity (higher δ 13 C carb) owing to invigoration of global-ocean overturning circulation and enhanced upwelling. Because the UKH event coincided with the FFB mass extinction, cooling rather than oceanic anoxia may have been the main killing mechanism.

May, A. (1996a): Relationship among sea-level fluctuation, biogeography, and bioevents of the Devonian: an attempt to approach a powerful, but simple model for complex long-range control of biotic crises. - Geolines, 3: 38-49, 2 figs.; Praha.

ABSTRACT. Connections among changing sea-level, development of marine biogeography and appearance of bioevents in Devonian times are emphasised. Decreasing Devonian provincialism of the marine fauna reflects rising sea-level of global ocean. Whereas the Emsian sea-level lowstand was accompanied by strong provincialism of the marine communities, the Frasnian highstands were linked to an unusual decrease of provincialism. As generally documented, the partial but intensive transgressional events (often related to bioevents) were usually associated with a decrease of the provincialism. The best explanation for the majority of Devonian bioevents is the effect of oceanic anoxia. A model suggested herein operates with a fast transgression related to fast ocean sea-level rise. A direct consequence of this fast transgression was the increased primary biomass production (caused by both increased infiux of nutrients and increased total surface of shallow seas). Decreased oxygen supply of oceans continued this process being caused by the global temperature increase which resulted from the albedo decrease. These consequences of these combined factors produced an oceanic anoxic event which started the extinction processes of the bioevent. The well-documented pattern of intensified biological crises during the Devonian, time-slice by time-slice (from Emsian to Frasnian), is explained as a direct result of decreased provincialism of the marine fauna. Both decrease of the provincialism and increased intensity of the Devonian bioevents can be deduced directly or indirectly from changes of global sea-level. This simply constructed but very complex explanation yields two advantages: first, it needs only very few infiuencing factors, second, it can basically renounce incalculable influences (e.g. meteorite impacts). The suggested concept of oceanic anoxic events can explain also other major bioevents of the Earth history.

KURZFASSUNG: Der Artikel versucht, Zusammenhänge zwischen den Veränderungen des Meeresspiegels, der Entwicklung der marinen Biogeographie und den Bioevents im Devon herauszuarbeiten und zu erklären. Die Entwicklung des Faunen-Provinzialismus im Devon ist ein Ergebnis der Entwicklung des globalen Meeresspiegels. Im Emsium war der Meeresspiegel niedrig und der Provinzialismus der Meeresfauna gross, im Frasnium war der Meeresspiegel hoch und der Provinzialismus sehr gering. Insbesondere einige Trangressions-Schübe, die sich auch als Bioevents bemerkbar machten, führten zu schnellen Abnahmen der Grösse des Provinzialismus. Die beste Erklärung für die meisten devonischen Bioevents ist das Auftreten von ozeanischen anoxischen Events. Das hier vorgestellte Modell setzt bei schnellen Transgressionen an, die durch schnelle Meeresspiegel-Anstiege verursacht wurden. Die Konsequenzen einer schnellen Transgression waren gesteigerte Primär produktion organischer Substanz und geringere Sauerstoff- Versorgung der Ozeane, was zusammen zum ozeanischen anoxischen Event und zum Bioevent führte. Der Umstand, dass die Intensität der Bioevents vom Emsium zum Frasnium zunahm, wird durch die Abnahme des Provinzialismus der Meeresfauna in dieser Zeit erklärt. Sowohl die Entwicklung des Provinzialismus der marinen Fauna als auch das Auftreten und die Intensität der Bioevents im Devon lassen sich direkt oder mittelbar aus der Entwicklung des globalen Meeresspiegels ableiten. Dieser sehr umfassende Erklärungsansatz hat den Vorteil, mit sehr wenigen Einfiussfaktoren auszukommen und auf unkalkulierbare Einwirkungen (wie z.B. Meteoriten-Einschläge) völlig verzichten zu können. Vermutlich ist das hier entwickelte Konzept eines ozeanischen anoxischen Events auch auf andere Bioevents übertragbar.

KEYWORDS: Devonian, Kellwasser Event, ecosystems, biogeography, sea level fiuctuation.

Preliminary review of taxonomy of the brachiopod order AĘpida and its stratigraphic distribution in the late Frasnian Kellwasser Crisis of several regions of Laurussia, westem Siberia and South China point to their moderate diversity and stepdown but irregular extinction pattern. The distinctive character of the late Frasnian atrypid fauna is emphasised by several relict genera, marked by recurrent and possibly aberrant characters (mainly in ornamentation types), tendency to size reduction and homeomorphy in some taxa. The transgressive/hypoxic Lower Kellwasser Event and preceding eustatic changes during the Palmatolepis rhenanaZone had only a regional destructive effect, and were linked rather to an enhanced dispersal of the last generic set of aĘpids. The VariaĘpinae, Spinatrypinae and Iowatryp,a-group seem to belong to the latest surviving atrypids. The final demise of the remaining atrypids (and some other articulate brachiopods, e.g., gypidulids) coincided with the fransgressiv...

Preliminary review of taxonomy of the brachiopod order AĘpida and its stratigraphic distribution in the late Frasnian Kellwasser Crisis of several regions of Laurussia, westem Siberia and South China point to their moderate diversity and stepdown but irregular extinction pattern. The distinctive character of the late Frasnian atrypid fauna is empha-sised by several relict genera, marked by recurrent and possibly aberrant characters (mainly in ornamentation types), tendency to size reduction and homeomorphy in some taxa. The transgressive/hypoxic Lower Kellwasser Event and preceding eustatic changes during the Palmatolepis rhenanaZone had only a regional destructive effect, and were linked rathęr to an enhanced dispersal of the last generic set of aĘpids. The VariaĘpi-nae, Spinatrypinae and Iowatryp,a-group seem to belong to the latest surviving atrypids. The final demise of the remaining atrypids (and some other articulate brachiopods, e.g., gypidulids) coincided with the fransgress...

&amp;amp;amp;amp;quot;The Upper Devonian Palliser Formation and its subsurface equivalent Wabamun Formation of western Canada comprise areally and volumetrically one of the largest epeiric carbonate platforms on Earth, covering some 600,000 km2 and reaching 600 m in thickness. Of Famennian age, these monotonous rocks formed in the aftermath of one of the great Paleozoic mass extinction events. Inboard of a ramp-like margin of gentle inclination (&amp;amp;amp;amp;lt;0.5°), the platform shallowed imperceptibly eastward, eventually becoming locally evaporitic in interior areas. The platform is thus characterized by a series of broad facies belts reflecting its relative shallowness and enormous width. Limestones cropping out in the southern and central Rocky Mountains represent mainly the outer and middle parts of the platform. These regions never developed facies cyclicity and the platform remained submerged. The Upper Devonian Palliser Formation and its subsurface equivalent Wabamun Formation of western Canada comprise areally and volumetrically one of the largest epeiric carbonate platforms on Earth, covering some 600,000 km2 and reaching 600 m in thickness. Of Famennian age, these monotonous rocks formed in the aftermath of one of the great Paleozoic mass extinction events. Inboard of a ramp-like margin of gentle inclination (&amp;amp;amp;amp;lt;0.5°), the platform shallowed imperceptibly eastward, eventually becoming locally evaporitic in interior areas. The platform is thus characterized by a series of broad facies belts reflecting its relative shallowness and enormous width. Limestones cropping out in the southern and central Rocky Mountains represent mainly the outer and middle parts of the platform. These regions never developed facies cyclicity and the platform remained submerged. Calcimudstones and peloidal wackestones overwhelmingly dominate with significant proportions of intraclasts, aggregates, dasycladalean calcareous algae, crinoid ossicles and minor amounts of brachiopods, gastropods, ostracodes and sponge spicules; bioturbation was ubiquitous and multi- generational. The shallow seafloor was flat and virtually featureless, with widespread meadows of algae and crinoids plus a few areas of low-relief stromatoporoidal patch reefs. In this storm-dominated system, the sediment surface of varying stiffness was swept and scoured frequently, leaving pack- to grainstones composed of rounded intraclasts and sediment-filled burrows. The abundance of algae and dominantly micritized aspect of crinoid ossicles suggest that the platform was mesotrophic, receiving elevated nutrient supply from the Ellesmerian orogen on the northern side of the craton. Although superficially uniform and ‘layer-cake’ in aspect, subtle compositional changes show that the platform exhibits four, hitherto unrecognized, long-term transgressive– regressive sequences, culminating in the demise of carbonate sedimentation and burial by nearly craton-wide black shales. Eustatic sea level and, more importantly, subsidence rate fluctuated during these sequences, with the third sequence characterized by subaerial exposure of the proximal region. Thicknesses calibrated to conodont biozones indicate that the marginal ramp had the greatest accumulation rate, although without any dramatic alteration of paleotopography. The ability of carbonate production to keep a balance with subsidence and eustasy over ~10 million years and hundreds of metres of strata yet not display in peritidal cycles is a characteristic shared by many other large platforms. It may reflect insufficient carbonate production rates, a higher energy regime, and off-platform sediment redeposition, coupled with stable mesotrophic conditions.&amp;amp;amp;amp;quot;

The cause of the Frasnian-Famennian boundary (FFB) biotic crisis, one of the &amp;quot; Big Five &amp;quot; Phanerozoic mass extinctions, remains poorly understood. Here, we generated a high-resolution uranium-isotope profile (δ 238 U) for a marine carbonate section at Baisha, South China, in order to document secular variation in mean global-ocean redox conditions and to compare its relationship to coeval changes in organic carbon burial fluxes (as proxied by δ 13 C carb) and global climate conditions. δ 238 U varied in a coordinated, mostly positive relationship with δ 13 C carb , indicating that expanded (reduced) oceanic anoxia was linked to lower (higher) productivity. This pattern is inconsistent with productivity control of redox conditions and suggests instead that both proxies responded to a common climatic forcing. We infer that climatic cooling (and glaciation during the Upper Kellwasser Horizon [UKH] event) led to better-ventilated oceanic conditions (higher δ 238 U) and greater productivity (higher δ 13 C carb) owing to invigoration of global-ocean overturning circulation and enhanced upwelling. Because the UKH event coincided with the FFB mass extinction, cooling rather than oceanic anoxia may have been the main killing mechanism.

The Red Marble of Baelen is a local ornamental stone from the Limbourg area (Vesdre valley, Eastern Belgium), where it has been quarried at least since the 16th century, possibly even from the 9th century. It represents a local Member of the Middle Famennian (late Upper Devonian) Souverain-Pré Formation. It is the only known or at least the only well-documented Mid Famennian red-stained carbonate mudmound complex worldwide. Carbonate microfacies comprise nodular to lenticular algospongal pack/bindstones and massive stromatactis-bearing microbialitic mudstones, both enclosing lenticular crinoidal grainto rudstones. Silty nodular bioclastic wacke/packstones, strongly affected by pressure solution, mark the transition with underlying and overlying micaceous sandstones and occur as interbeds within the mudmound core. The Red Marble of Baelen displays a few varieties that have been used for a large spectrum of building and decorative purposes, mostly within a short radius of the producti...

The paper focuses on high-resolution multidisciplinary research on three Devonian–Carboniferous boundary sections in shallow-water carbonate rocks in the Namur–Dinant Basin (Belgium, France). The aim of the study is to provide palaeo-environmental reconstructions and correlations supported by several independent quantitative proxies. We describe several correlative horizons and provide their sequence-stratigraphic interpretation based on facies analysis, spectral gamma-ray data, element concentrations (XRF) and 13Ccarb, with foraminifer-biostratigraphy age control. The most prominent surface is a basal surface of forced regression, which is indicated by a sharp basinward facies shift and a drop in clay-gamma-ray values and Al concentrations at the base of the Hastière and Avesnelles formations in more distal settings. In proximal settings, this surface merges with a hiatus at the Devonian–Carboniferous boundary inferred from foraminifer biostratigraphy. This hiatus can be correlated with the global Hangenberg sandstone event, which indicates a glacioeustatic sea-level fall. Increasing values of Zr/Al, K/Al, Sr/Al and Mn/Al coincide with the proximal facies of the falling stage system tract (FSST) and lowstand system tract (LST) in the Hastière and Avesnelles formations as a consequence of the enhanced input of siliciclastics and nutrients during low sea levels. The top of the middle Hastière member is interpreted as the maximum regression surface, which is overlain by transgressive systems tract (TST) of the upper Hastière member. The patterns of gamma-ray, δ13Ccarb, Th/K, Al, Zr/Al, and Mn/Al curves are well correlated between the studied sections. The δ13Ccarb excursions are correlated with the unnamed excursion in the Upper expansa conodont zone (Carnic Alps) and with the global Hangenberg event s.l. excursion in the kockeli conodont zone. This sequence-stratigraphic framework is used for correlations with deltaic successions from the Tafilalt Basin, Morocco.
The basal surface of the forced regression equivalent to the Hangenberg sandstone event, which is typical for deeper-water settings, is easily recognisable and correlatable with gaps in more-shallow water settings. We suggest that it should be taken into account as a possible candidate for the “natural solution” of the Devonian–Carboniferous boundary in discussions concerning its redefinition.

The Red Marble of Baelen is a local ornamental stone from the Limbourg area (Vesdre valley, Eastern Belgium), where it has been quarried at least since the 16th century, possibly even from the 9th century. It represents a local Member of the Middle Famennian (late Upper Devonian) Souverain-Pré Formation. It is the only known or at least the only well-documented Mid Famennian red-stained carbonate mudmound complex worldwide. Carbonate microfacies comprise nodular to lenticular algospongal pack/bindstones and massive stromatactis-bearing microbialitic mudstones, both enclosing lenticular crinoidal grain- to rudstones. Silty nodular bioclastic wacke/packstones, strongly affected by pressure solution, mark the transition with underlying and overlying micaceous sandstones and occur as interbeds within the mudmound core. The Red Marble of Baelen displays a few varieties that have been used for a large spectrum of building and decorative purposes, mostly within a short radius of the production sites, in the former Duchy of Limbourg. Its usage was rural and vernacular, although it has been exceptionally employed in prestigious buildings such as the Antwerp town hall.

May, A. (1997g): Ein Modell zur Erklärung der Bio-Events und der biogeographischen Entwicklung im Devon durch den Meeresspiegel. - Dortmunder Beiträge zur Landeskunde, Naturwissenschaftliche Mitteilungen, 31: 137-174, 5 figs.; Dortmund.

Abstract: The attempt is made, to show and to explain connections between the changing sea-Ievel, marine biogeography, and bio-events within the Devonian. The Devonian development of marine faunal provincialism is the result of changes in global sea-Ievel. Within the Emsian sea-Ievel was low and marine faunal provincialism was strong, while within the Frasnian sea-Ievel was high and marine faunal provincialism was weak. Some particular transgressive intervals made themselves felt as bio-events, conducive to fast decreases in the intensity of provincialism. Starting with the Daleje Event of the Emsian and ending with the Kellwasser Event of the Frasnian, the bio-events are discussed in detail. In this context new data concerning the Middle Devonian of the Eastern Rhenish Massif are presented. The best explanation for most Devonian bio-events is the occurrence of oceanic anoxic events. The model presented here uses fast transgressions caused by rapid sea-Ievel rises (see fig. 1). Fast transgression increased primary biomass production (caused by an increased influx of nutrients and an increased area of shallow sea) and decreased oxygen supply in the oceans (caused by global temperature increase resulting from albedo decrease). Both factors together resulted in the oceanic anoxic event conducive to the bio-event. The fact, that bio-event intensity increased from the Emsian to the Frasnian is explained by the decrease of marine faunal provincialism within this time. Both the development of provincialism and the occurrence and intensity of bio-events within the Devonian can be deduced directly or indirectly from the changes in global sea-Ievel. This comprehensive attempt at explanation has the advantage of needing only a few influencing factors and renouncing incalculable influences (e. g. meteorite impacts). Possibly, the model of oceanic anoxic events presented is also transferable to other bio-events (e. g.: bio-events of the Famennian, Cenomanian/Turonian Event). Kurzfassung: Der Artikel versucht, Zusammenhänge zwischen den Veränderungen des Meeresspiegels, der Entwicklung der marinen Biogeographie und den Bio-Events im Devon herauszuarbeiten und zu erklären. Die Entwicklung des Faunen-Provinzialismus im Devon ist ein Ergebnis der Entwicklung des globalen Meeresspiegels. Im Emsium war der Meeresspiegel niedrig und der Provinzialismus der Meeresfauna groß, im Frasnium war der Meeresspiegel hoch und der Provinzialismus sehr gering. Insbesondere einige Trangressions-Schübe, die sich auch als Bio-Events bemerkbar machten, führten zu schnellen Abnahmen der Größe des Provinzialismus. Die Bio-Events vom Daleje-Event des Emsiums bis zum Kellwasser-Event des Frasniums werden detailliert besprochen. In diesem Zusammenhang werden auch neue Daten zum Mitteldevon des Rechtsrheinischen Schiefergebirges gegeben. Die beste Erklärung für die meisten devonischen Bio-Events ist das Auftreten von ozeanischen anoxischen Events. Das hier vorgestellte Modell setzt bei schnellen Transgressionen an, die durch schnelle Meeresspiegel-Anstiege verursacht wurden (siehe Abb. 1). Die Konsequenzen einer schnellen Transgression waren gesteigerte Primärproduktion organischer Substanz und geringere Sauerstoff-Versorgung der Ozeane, was zusammen zum ozeanischen anoxischen Event und zum Bio-Event führte. Der Umstand, daß die Intensität der Bio-Events vom Emsium zum Frasnium zunahm, wird durch die Abnahme des Provinzialismus der Meeresfauna in dieser Zeit erklärt. Sowohl die Entwicklung des Provinzialismus der marinen Fauna als auch das Auftreten und die Intensität der Bio-Events im Devon lassen sich direkt oder mittelbar aus der Entwicklung des globalen Meeresspiegels ableiten. Dieser sehr umfassende Erklärungsansatz hat den Vorteil, mit sehr wenigen Einflußfaktoren auszukommen und auf unkalkulierbare Einwirkungen (wie z. B. Meteoriten-Einschläge) völlig verzichten zu können. Vermutlich ist das hier entwickelte Konzept eines ozeanischen anoxischen Events auch auf andere Bio-Events übertragbar.

In order to contribute to assessment of the aftermath of the Hangenberg Biological Crisis that took place at the top of the Famennian (Upper Devonian), the strophomenid, orthotetid and orthid brachiopods from the ‘Strunian’-aged Etroeungt Limestone Formation (Avesnois, northern France) are described. The Avesnois is the historical type area of the ‘Strunian’, traditionally considered as the last Famennian substage. Although they are sometimes abundant in the studied sections, their generic and specific diversity is very low in the Etroeungt Limestone Formation. Moreover, the majority of the species belong to long-ranging genera (Leptagonia, Schellwienella?, Schizophoria, Aulacella).

The almost complete post-protaspid ontogenetic sequence and the hitherto unknown hypostome of a Late Devonian blind proetid,Helioproetus costifusus, are described. The silicified meraspid remains were recovered from the lower part of the Upper Clymenien-Schichten of late Famennian (Dasbergian) age from Breternitz near Saalfeld, Thuringia. The course of the facial suture inH. costifusus is in early ontogenetic stages similar to that of adults of the youngerH. carintiacus, present in the upper part of the same section. This observation suggests an ancestor-descendent relationship between the two species, implying processes of heterochrony. The smallest cranidia of H. costifusus also exhibit a particular overall morphology and a remnant of a straight palpebral suture indicating that this species may have had a sighted cyrtosymboline ancestor. The Early Carboniferous Pedinocoryphe is considered to have evolved in a convergent way from a common rootstock.