Frasnian-Famennian Extinction Event Research Articles

Contourite-drift archive links Late Devonian bioevents with periodic anoxic shelf water cascading

Analysis of a Devonian contourite depositional system in the eastern Anti-Atlas of Morocco reveals the formation of widespread erosional hiatuses and organic-rich bioclastic contourites (ORCs) coinciding with the expansion of an anoxic water mass during Frasnian bioevents, ultimately culminating in the Kellwasser crisis (Frasnian-Famennian extinction event). The identified contourite terrace formed on the uppermost slope of the northern passive margin of Gondwana. Its inner part was bounded by an along-slope contourite channel and a small mounded drift at its downslope margin. Facies- and drift-scale contourite features evidence northwest-directed bottom currents driven by repeated overflows of dense, highly saline, anoxic water originating from the northern Gondwana Epicontinental Sea. These periodic overflows were channeled through the Ougarta trough, then deflected westward over the Tafilalt contourite terrace by the Coriolis force and cascaded downslope until reaching a density equilibrium level, probably forming an intermediate water mass. The cascading of dense, anoxic shelf water supports the photic-zone eutrophication (top-down) model proposed for the Kellwasser crisis and related Devonian anoxic events. We propose a direct link between the anoxic overflows and the Devonian evolutionary events.

A new model for the Kellwasser Anoxia Events (Late Devonian): Shallow water anoxia in an open oceanic setting in the Central Asian Orogenic Belt

The Frasnian–Famennian mass extinction event devastated tropical marine ecosystems and ranks in the top six in taxonomic and ecological severity. The close stratigraphic association between the extinction and the Kellwasser Anoxia Events support a link between oceanographic anoxia and extinction. The Upper and Lower Kellwasser horizons have been identified in epicontinental and basinal settings in Laurussia, Gondwana, Siberia, and South China. The Hongguleleng Formation (Late Devonian) in northwestern Xinjiang, China, contains both the Frasnian–Famennian boundary and the rebound from the Frasnian–Famennian extinction event in a highly fossiliferous shallow marine setting associated with a Devonian oceanic island arc complex (part of the Central Asian Orogenic Belt, or CAOB). Here we show that the Hongguleleng Formation also records the Upper Kellwasser Anoxia Event through analysis of multiple geochemical proxies. In contrast to previous studies asserting that the Kellwasser Events were restricted to epicontinental seaways and basins, our results indicate that it occurred not only along the shallow continental margins of the closing Rheic Ocean, but also in shallow water in the open oceanic part of Paleotethys. Previous explanations for the Kellwasser Events from epicontinental margins and basins call for the migration of deep anoxic bottom water into shallow water environments as a kill mechanism for shallow marine ecosystems or attribute it to sea level rise and subsequent stagnation. There is no evidence that the Devonian oceans completely overturned during the Kellwasser Events; similarly, many transgressive events in the Devonian are not associated with black shales. We therefore suggest an alternative mechanism for the Kellwasser Events based on new evidence from the CAOB, where anoxia is driven by episodic eutrophication of surface waters.

Encrustation patterns on post-extinction early Famennian (Late Devonian) brachiopods from Russia

A study of patterns of episkeletobiont encrustation on the shells of two early Famennian brachiopods, Cyrtospirifer zadonicus and Ripidiorhynchus huotinus from Russia, revealed assemblages comprising seven skeletonised encruster taxa. The assemblages are dominated by spirorbiform microconchids, followed by cornulitids. Features such as shell malformations, frequent encruster growth towards the commissure of the shells, and encruster distribution in the areas adjacent to zones of possible water intake by the brachiopods indicate that these may have been colonised syn vivo. The lack of differences in encruster abundance between the two valves in C. zadonicus indicates that this species may have lived with both valves inclined at a high angle to the substrate. The significantly higher abundance of episkeletobionts on the brachial valves of R. huotinus may indicate that shells of this species were oriented with the brachial valve at a lower angle to the substrate, providing sheltered sites for coelobiotic larvae. Compared with pre-Famennian brachiopod-hosted encruster communities, this early Famennian community is impoverished in species richness and is dominated by microconchids. It is proposed that the epibionts witnessed a regression-related Frasnian–Famennian extinction event. During the recovery interval, opportunistic microconchids may have been among the first encrusters to colonise the pioneering brachiopods.

Anatomical reinvestigation of Archaeopteris macilenta from the Upper Devonian (Frasnian) of South China

Archaeopteris macilenta is one of the most widespread plants in the Late Devonian. Based on fossils from the Frasnian Huangjiadeng Formation, Yichang District of Hubei Province, for the first time we study in detail the anatomy of this progymnosperm plant in South China. Ultimate axes are protostelic with three xylem sympodia and lack secondary tissue. Penultimate axes are eustelic, bearing eight sympodia and a thin band of secondary xylem. Radially symmetrical sympodia of mesarch primary xylem produce traces of appendages in a spiral arrangement. Archaeopteris macilenta and A. halliana (A. roemeriana) are dominant in the Frasnian and Famennian, respectively. Comparisons with these two species from other tectonic plates indicate consistent stelar architectures. Global spread, continuous occurrence, and identical anatomy during the Late Devonian indicate that Archaeopteris survived the Frasnian–Famennian extinction event. In this time, endemic genera and cosmopolitan taxa, including Archaeopteris, suggest the palaeogeographic isolation of South China and certain associations with other plates.

Large extinctions of articulate brachiopods in the paleozoic and their ecological and evolutionary consequences

The largest Paleozoic extinctions of articulate brachiopods occurred at the Frasnian—Famennian boundary in the Late Devonian and at the Permian—Triassic boundary. Both extinctions affected taxa of all levels, including orders, but differed in scale, course, and ecological and evolutionary consequences. The Frasnian—Famennian extinction event was selective and evolutionary activity after the crisis varied in different orders. However, in the Early Carboniferous, the brachiopod diversity was mostly restored in comparison with the Devonian maximum. In particular groups, preadaptation played a role in changes in diversity and reconstruction of communities. The brachiopod composition at this boundary changed sharply. The extinction event at the end of Permian was global and accompanied by changes in the biota. Later, in the Meso-Cenozoic, the brachiopod diversity was not restored, and bivalves acquired primary importance in various bottom communities of different sea zones where Paleozoic brachiopods previously dominated. Extinction of brachiopods at this boundary was long and gradual. The symptoms of the ecological crisis in the development of Permian brachiopods are recognized beginning from the Roadian Age, which was probably the onset of this crisis.

Microbial mounds prior to the Frasnian-Famennian mass extinctions, Hantang, Guilin, South China

Late Frasnian mounds of the Yunghsien Formation, Guilin, South China, developed as part of the Guilin platform, mostly in reef-flat and platform margin settings. Microbial mounds in platform margin settings at Hantang, about 10 km west of Guilin, contain Frasnian biota, such as Stachyodes and Kuangxiastraea and, thus, occur below the Frasnian-Famennian mass extinction boundary. Platform margin facies were dominated by microbes, algae and receptaculitids. Massive corals and stromatoporoids are not common and rarely show reef-building functions as they did in Givetian time. The margin mounds are composed of brachiopod-receptaculitid cementstone, and a variety of boundstones that contain Rothpletzella, Renalcis, thrombolite and stromatolite. Other microbial communities include Girvanella, Izhella, Ortonella and Wetheredella. Solenoporoid algae are abundant locally. Zebra structures and neptunian dykes are well-developed at some intervals. Pervasive early cementation played an important role in lithification of the microbial boundstones and rudstones. Frasnian reefs of many regions of the world were constructed by stromatoporoids and corals, although a shift to calcimicrobe-dominated frameworks occurred before the Famennian. However, the exact ages of many Frasnian margin outcrops are poorly constrained owing to difficulties dating shallow carbonate facies. The Hantang mounds represent a microbe-dominated reef-building community with rare skeletal reef builders, consistent with major Late Devonian changes in reef composition, diversity and guild structure occurring before the end of the Frasnian. A similar transition occurred in the Canning Basin of Western Australia, but coeval successions in North America, Western Europe and the northern Urals are either less well-known or represent different bathymetric settings. The transition in reef-building style below the Frasnian-Famennian boundary is documented here in the two best exposed successions on two continents, which may have been global. Set in the larger context of Late Devonian and Mississippian microbial reef-building, the Hantang mounds help to demonstrate that controls on microbial reef communities differed from those on larger skeletal reef biota. Calcimicrobes replaced stromatoporoids as major reef builders before the Frasnian-Famennian extinction event, and increasing stromatoporoid diversity towards the end of the Famennian did not result in a resurgence of skeletal reef frameworks. Calcimicrobes dominated margin facies through the Famennian, but declined near the Devonian-Carboniferous boundary. Stromatolite and thrombolite facies, which occurred behind the mound margin at Hantang, rose to dominate Mississippian shallow-water reef frameworks with only a minor resurgence of the important Frasnian calcimicrobe Renalcis in the Visean when well-skeletonized organisms (corals) also became volumetrically significant frame builders again.

Late Devonian conodonts and the global Frasnian-Famennian extinction event, Thong Pha Phum, western Thailand

The study of Late Devonian Frasnian and Famennian conodonts in western Thailand confirms these species are mostly cosmopolitan. The Thailand section includes the Upper Kellwasser Event recorded in Europe, North America, China, and elsewhere, and probably also includes the upper part of the Lower Kellwasser Event. Stable isotope geochemistry for this interval shows a positive d13C excursion in the Late rhenana conodont Zone followed by a gradual return to normal, followed by a sudden positive excursion near the conodont extinction event. The latter has been chosen elsewhere as the Frasnian-Famennian boundary. The extinction event seems a consequence of unsteady conditions that could include eutrophic, oxygen, carbon dioxide, eustatic, and temperature fluctuations. There was a regional disappearance or extinction of several conodont species at the Frasnian-Famennian boundary followed by recovery and the spread of new species during the early Famennian.

Famennian (Upper Devonian) calcimicrobial ( Renalcis) reef at Miaomen, Guilin, Guangxi, South China

Famennian (Upper Devonian) reefs represent a calcimicrobial and stromatolitic reef framework with a few skeleton-dominated (stromatoporoid) examples after the skeletal metazoans in reef ecosystems were impacted on a global scale by the Frasnian–Famennian extinction event. Calcimicrobes, thrombolites, stromatolites, and biologically induced cement formed the major part of reef framework volume and contributed to rigidity of reefs. In this study, one example of Famennian non-skeletal carbonate buildups at Miaomen, Guilin, South China, has been documented in detail. Thick and massive limestones in the platform margin facies show a lateral transition to well-bedded fenestral and laminated limestone in the back-reef facies southeastward and to well-bedded intraclastic grainstone, mudstone, and shale with lithoclasts and breccias in fore-reef slope facies northwestward. The Miaomen reef is almost exclusively constructed by calcimicrobes and cement. Major reef builders are Renalcis, Izhella, Paraepiphyton, Garwoodia, and a ‘ Keega’-like microbe. Other reef builders are Wetheredella, Rivularia, Rothpletzella, Ortonella, and Girvanella. Some less common algae and calcimicrobes also occur in the Miaomen reef, including Parachaetetes, Solenopora, Tharama-like objects, and unidentifiable microbes. Cavities are well developed in the reef limestone. The Miaomen Renalcis reefs developed along leeward platform margin settings adjoined by intraplatform depressions and rimmed Famennian carbonate platforms along with stromatolite reefs, ooid shoals, brachiopod-shell shoals, nautiloid shoals, and previously described Renalcis–Epiphyton and Renalcis-cement reefs. Miaomen reefs demonstrate the significant roles of calcimicrobes and microbial carbonates in the development of Famennian carbonate systems in South China. Famennian microbial reefs in Guilin represent an interval of profound biotic change in the style and extent of carbonate buildups and in the composition of buildup communities and indicate important environmental and ecological changes within the carbonate system.

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Research Article| April 01, 2003 Reply Michael M. Joachimski; Michael M. Joachimski 1Institut für Geologie und Mineralogie, Schlossgarten 5, 91054 Erlangen, Germany Search for other works by this author on: GSW Google Scholar Werner Buggisch Werner Buggisch 1Institut für Geologie und Mineralogie, Schlossgarten 5, 91054 Erlangen, Germany Search for other works by this author on: GSW Google Scholar Geology (2003) 31 (4): 384. https://doi.org/10.1130/0091-7613(2003)031<0384:>2.0.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Michael M. Joachimski, Werner Buggisch; Reply. Geology 2003;; 31 (4): 384. doi: https://doi.org/10.1130/0091-7613(2003)031<0384:>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Gong and Xu question whether the positive excursions in conodont apatite δ18O during the Late Frasnian and Frasnian-Famennian transition are the effect of climatic cooling. Instead, they favor changes in surface-water salinity in order to account for the observed shifts in δ18O of +1‰ to +1.5‰. Gong and Xu do not provide any data that may support higher surface-water salinity during the late Frasnian, but speculate on hypersalinity, red tides, and anoxia as potential causes of the Frasnian-Famennian extinction event. To our understanding, a change in surface-water salinity is not plausible. The studied sections were situated... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Famennian mud-mounds in the proximal fore-reef slope, Canning Basin, Western Australia

Famennian (Late Devonian) carbonate buildups and, in particular, mud-mounds, are poorly known, in general, and few have been documented in detail. Relatively small Famennian mud-mounds occur in proximal fore-reef slope settings in the Canning Basin, Western Australia. The Famennian platform margin facies passes from typical shoaling carbonate facies in the back reef, through massive, calcimicrobial, cement-rich reef-margin facies, to relatively steeply dipping (20–30°), well-bedded fore-reef slope facies containing shelf-derived, winnowed grainy sediments and extremely coarse reef-block debris. Isolated or coalescing mounds occur in the proximal slope, immediately adjacent to and, in some cases, possibly grading into the margin facies. Mounds are elongate perpendicular to the margin and some had synoptic relief greater than 2 m. Mounds are lithologically variable and consist of varying proportions of micrite, multiple generations of marine cement, abundant Rothpletzella, Renalcis, poorly preserved sparry microbial crusts and sporadically distributed laminar stromatoporoids. Surrounding grainy slope facies abut and slope off of mound flanks. Mound facies are very similar to nearby reef-margin facies, with the exceptions that stromatoporoids have not been observed in margin facies and solenoporoid algae, which occur in the margin, have not been observed in the mounds. Stromatolites are conspicuously absent from both facies. Mound facies appear to be more closely related to Frasnian and Famennian calcimicrobe cement-dominated reef-margin facies than to Famennian deep-water stromatolite–sponge-mound facies, such as those that occur elsewhere in the Canning Basin. The observed Canning Famennian reef and mound frameworks were constructed by communities that appear to be very similar to earlier Frasnian communities, despite the Frasnian–Famennian extinction event, and provide good examples of microbial reef framework construction in a high energy setting.

Laurussian land-plant diversity during the Silurian and Devonian: mass extinction, sampling bias, or both?

In phytogeographic data sets, the number of assemblages or floras from each interval may provide a test of the influence of sampling intensity on land-plant diversity. Using a data set of Silurian and Devonian compression-impression plant genera from Laurussia and the Acadian terrain, regression of five measures of land-plant diversity (total diversity, mean genus richness of floras, median assemblage diversity, most diverse assemblage, and standing diversity at interval boundaries) against the number assemblages or floras from thirteen intervals suggests that sampling bias influences all of the diversity measures to some extent, including within-habitat measures. The standing diversity of land plants at interval boundaries, the measure least influenced by sampling (r= 0.65,p= 0.05), increased steadily from the Middle Silurian to the late Givetian/early–middle Frasnian boundary, fell sharply in the early–middle Frasnian and remained low throughout the late Frasnian–middle Famennian. Standing diversity rose dramatically in the late Famennian and Strunian (latest Devonian): the Frasnian–Famennian extinction event may have affected land plants. The standing diversity of Silurian and Devonian microspore genera at interval boundaries mirrors that of compression-impression genera: neither record supports a land-plant diversity equilibrium during the Devonian.

The Frasnian-Famennian extinction event in a stable cratonic shelf setting: Trout River, Northwest Territories, Canada

The Frasnian-Famennian (F-F) extinction event occurs in platformal carbonates along the Trout River, N.W.T. Paleogeographically the site was about 150 km east of the western cratonic margin. Faunal evidence, based primarily on corals, and sedimentation rates of passive cratonic margins suggest that the late Frasnian Redknife and Kakisa Formations include both the Upper rhenana and the linguiformis conodont zones. The high biodiversity of the benthic fauna during the late Frasnian decreases sharply at the F-F boundary and recovers only gradually during the early Famennian. This trend is also expressed by the profile of δ 13C values. Microfacies analysis has identified two minor hiatuses at the F-F boundary. The lower break is represented by an unconformity at the upper contact of the latest Frasnian Kakisa Formation and is associated with surficial karstification and brecciation of the underlying biostromal carbonates. Anomalous trace element concentrations at the unconformity are interpreted as possible fallout material related to a bolide impact. This hiatus probably corresponds to the Lower triangularis Zone, because no diagnostic conodonts of that time interval are present. The lower and upper hiatuses are separated by the deposition of a wackestone-sandstone facies with an impoverished fauna of sponges, calcareous algae and some foraminifera, preserved only in neptunian dykes in the upper Kakisa and as fragments in the overlying Famennian Trout River Formation. The depauperate fauna suggests hostile conditions and/or a habitat ravaged by a catastrophic event—common characteristics after a global extinction event. Conodont evidence suggests that this brief depositional interval corresponds to the Middle triangularis Zone. The upper hiatus probably straddles the contact of the Middle and Upper triangularis zones. Evidence for this break are angular fragments of the wackestone-sandstone facies in the basal Trout River Formation. Conodonts from the basal siliciclastics of the Trout River Formation assign the lower part of this unit to the Upper triangularis Zone. In Alberta, 900 km to the south, similar platformal carbonates show a longer hiatus (the entire triangularis Zone) at the F-F contact, whereas slope sediments indicate continuous sedimentation with a sharp drop in biodiversity and a temporary proliferation of primitive organisms at the F-F boundary.

Paleobiogeographic significance of Famennian echinoderm faunas from northwestern China

A diverse (&gt;200 specimens representing more than 20 taxa) Famennian echinoderm fauna has been collected from the Hongguleleng Formation, Junggar Basin, Xinjiang, Uygur Autonomous Region, Peoples Republic of China. Famennian faunas are relatively poorly known on a global basis, Famennian echinoderm faunas in general are very poorly known, and echinoderm faunas of any age from China are virtually unstudied. Echinoderms are highly endemic, which makes them relatively poor for global biostratigraphy, but excellent for use in biogeographic studies. Because Frasnian and Famennian faunas are noted for their general lack of endemism, echinoderms may be critical, sensitive indicators of Famennian biogeographic provinces. Preliminary analysis indicates that this Chinese Famennian echinoderm fauna is dominated by blastoids and inadunate, small-calyx camerate, and flexible crinoids, many of which show morphological characters that are intermediate in nature at higher classificatory levels between older Devonian and younger Carboniferous taxa. The taxonomic composition of this fauna clearly indicates that diversification and re-radiation in the aftermath of the Frasnian-Famennian extinction event was well underway before the close of the Famennian. The most similar faunas are from Famennian rocks of England and, possibly, Germany. Brachiopods, corals, and trilobites of this age also show similarities between northwestern China and western Europe. These two areas were high latitudinal and tropical, respectively, during deposition, therefore their similar composition may represent latitudinal contraction associated with global cooling or a nearshore migratory pathway between the two areas via Kazahkstan and Poland.

Effect of the Frasnian-Famennian extinction event on the stromatoporoids

Although Paleozoic stromatoporoids were drastically reduced in abundance and diversity by the Frasnian-Famennian (F/F) mass extinction event, at least 20 genera (mostly labechiids and clathrodictyids) are known from latest Devonian rocks. Some typical Frasnian genera survived the F/F crisis to die out in early Famennian time, and others took part in the Strunian resurgence of the stromatoporoids. Small stromatoporoid reefs are known from Famennian and Strunian rocks. The history of the group suggests a large, rapid, but progressive environmental change at the F/F boundary and the survival of genera better adapted to cool water.