Late Frasnian Research Articles

Neverovsky Palaeoreef and Associated Deep-Marine Facies: High-Value Late Devonian Geoheritage from the Rudny Altai

The Rudny Altai is a western segment of the Altai orogenic belt. Its geological richness makes its geoheritage exploration an urgent matter. Investigations in the Loktevsky District (Altai Region, Russian Federation) have led to the finding of three notable localities, which are proposed as geosites. Field investigations and both qualitative and semi-quantitative (scoring by criteria) studies were carried out to characterize and value the geoheritage properties of these localities. The Neverovsky palaeoreef is a relatively large geosite, representing a Frasnian reef developed on a volcanic edifice. The Zolotukha section and the Razdolnoe section are smaller geosites representing deep-marine facies of the Giventian–Frasnian transition and the late Frasnian, respectively. Seven geoheritage types are established in the Neverovsky palaeoreef, and four geoheritage types are established in the other two geosites. Examination of rarity, accessibility, vulnerability, and other properties allows the ranking of the Neverovsky palaeoreef globally and the other two geosites regionally. The three proposed geosites need special geoconservation measures (especially regarding their rich fossil content). The palaeoreef can be used for the promotion of local tourism.

Conodont biostratigraphy, carbonate microfacies and climate changes during the Late Devonain (Frasnian–Famennian) in the Preslavtsi 2 well (Moesian Terrane, NE Bulgaria)

Five conodont zones (falsiovalis, rhenana, triangularis, marginifera, and praesulcata) were recognized within the Upper Devonian carbonate sequence in the Preslavtsi 2 well from the Moesian Terrane in NE Bulgaria. Microfacies study indicates a climate change (from the Subtropical Arid to the Warm Temperate Climatic Zones) recorded in the Frasnian–Famennian succession. Thus, during the Givetian and early Frasnian, sedimentation took place in an arid tidal flat setting, where microbial mats and lagoon carbonates have been formed. In the late Frasnian, a transgression, followed by a rapid regression was recorded that are presumably related to the Late Devonian Kellwasser event. At the beginning of the Famennian, a climate change has occurred and various shallow- and open-marine carbonates have been formed under warm temperate climate conditions.

Trilobites showed strong resilience capacity through the Late Devonian events despite an inexorable decline

The Kellwasser events constituted a major biocrisis at the Frasnian–Famennian boundary, that killed many organisms. The subsequent Hangenberg event also had important effects on marine fauna, although it is not traditionally considered a mass extinction. This study aims to understand the tempo and mode of the Late Devonian extinctions using trilobites as a case of study. To estimate the trilobite dynamics both taxonomic richness and morphological disparity were assessed. The diversity was calculated using conodont biozones, which provide a high-resolution timeline, allowing tracking changes in taxonomic richness and the environmental events implied. The morphological disparity was analysed using space occupancy measures and visualized in morphospaces. The Frasnian began with a diversification of trilobites at generic levels. The number of orders remained constant and relatively high with the presence of Corynexochida, Harpetida, Odontopleurida, Phacopida and Proetida. Environmental conditions were favourable for the proliferation of trilobites until the late Frasnian. However, the Kellwasser events disrupted trilobite evolution, leading to a double extinction event. A first random extinction affected low taxonomic levels, while the second extinction was selective, causing losses at both the generic and order levels, and a strong decrease in morphological disparity. Nonetheless, in response to the end-Frasnian environmental changes, blind and reduced-eye trilobites became more common. Following a dip in generic richness at the beginning of the Famennian, the two surviving orders, Phacopida and Proetida, recovered. Although no novelties characterized them, they partially refilled the morphospace. A slight decline occurred in the middle Famennian before a strong morphological and taxonomical diversification was identified in the expansa and preasulcata zones. The final Hangenberg event at the end of the Famennian affected trilobites at all taxonomic ranks as the Kellwasser events. Only Proetida survived.

Conodont size in time and space: Beyond the temperature-size rule

The temperature-size rule (TSR) states that ectotherms mature at smaller adult body size in warmer conditions. Such a rule may have the potential to explain size response of fossil organisms to past temperature variations, but its validity in deep time has been seldom tested. The generality of this rule was investigated here by compiling data documenting the size record of three conodont genera (Palmatolepis, Ancyrodella and Polygnathus) at different spatial and temporal scales during the Late Frasnian and the Famennian, characterized by short- and long-term temperature variations. Statistical models were used to investigate the relationship between conodont size and oxygen isotope values, considered as paleotemperature proxies. Comparison of evolutionary models further allowed to test alternative modes of size variation such as stasis or punctuation.The TSR was not validated as a general rule explaining size variation in these fossil records, being only observed as a large-scale geographic trend during a time-slice. The only strong support for temperature being the driver of temporal variations was found regarding the size of Palmatolepis during the Kellwasser period, but the relationship was reverse to the expectation of the TSR. The absence of general TSR pattern is probably due to the interference of many other factors (demography and mortality patterns, temperature tolerance, size reduction due to stress) whose relative importance may depend on the time interval and the genus considered. Rather than a correlation with environmental proxies, evolutionary models suggested the occurrence of a synchronous shift in Palmatolepis size around 369 Ma (Palmatolepis termini conodont Zone) in several outcrops, raising questions about the environmental forcing beyond this shift. Departures from the expected TSR may thus provide relevant insights into the complex interplay of physical, tectonic and eco-evolutionary processes impacting size evolution in deep time.

Depositional setting and organic matter characterization of the Upper Devonian Antrim Shale, Michigan Basin: Implications for hydrocarbon potential

During the Late Devonian, the Michigan Basin in the Eastern Interior Seaway was characterized by phases of well-developed bottom water anoxia, triggering extensive accumulation of organic matter-rich black shales. Palynological analysis for paleoenvironmental reconstruction and biostratigraphy of the Upper Devonian rocks has been previously performed in other basins of eastern North America, but it is lacking in the Michigan Basin. Here, the Upper Devonian Antrim Shale Formation is investigated for biostratigraphic, paleoenvironmental, and sea level reconstructions, organic matter characterization, and source rock potential. 35 core samples from three drill holes across the Michigan Basin spanning the Norwood, Paxton, Lachine, and Upper members. Palynological analysis showed a moderately diverse assemblage of 31 genera represented by 53 species of relatively well-preserved prasinophyte phycomata and acritarchs, with sparse records of plant spores and freshwater algae. Based on marker prasinophytes and acritarchs, an age of late Frasnian was assigned to the Norwood and Paxton members, while an early Famennian age was proposed to the Lachine and Upper members of the Antrim Shale. Two palynofacies assemblages (PFA) were identified from the variation in the particulate organic matter (POM) composition, both of which indicate deposition in a distal inner neritic shelf environment, but the PFA-2 took place in slightly shallower conditions than the PFA-1. Geochemical screening indicated high organic matter content (up to 25 wt%, avg. 8.5 wt%) and excellent hydrocarbon generating potential of kerogen Type II for the Norwood, Lachine, and Upper members. Only the Paxton Member was dominated by poor to fair organic richness (<0.6 wt%) and low hydrocarbon potential with a mixed Type II/III kerogen. Organic petrography indicated that the dominant organic matter assemblage consists mainly of unicellular marine Tasmanites telalginite and Leiosphaeridia, followed by solid bitumen of the initial oil type. Thermal maturity, determined from VRo-eq and Tmax, indicated that all samples are in the oil window, except for some intervals in the Paxton Member.

Revision of Middle Devonian conodont biostratigraphy in the Negheleh section, Central Iran

Fifteen conodont species and subspecies from the Negheleh section, Soh area, north of Esfahan represent early Eifelian to middle Givetian time interval. Five biozones: costatus to australis, kockelianus, ensensis to hemiansatus, timorensis and rhenanus to ansatusare recognized. The present study suggests the Eifelian age for the base of Bahram Formation in the Sanandaj-Sirjan and the western part of Central Iran Microplate. The oldest known occurrence of thelodont turiinid species, Neoturinia hutkensis is reported from the early Eifelian strata of the Negheleh section. New age range from the late Eifelian to late Frasnian is proposed for Icriodus excavatus Weddige.Keywords: Middle Devonian, Eifelian, Givetian, conodonts, biostratigraphy.

BIOSTRATIGRAPHY AND CORRELATION OF DEVONIAN DEPOSITS IN THE SOUTH-WEST SEGMENT OF THE EAST-EUROPEAN PLATFORM BY BRACHIOPODS

The main aim of the paper is to study the detailed distribution of the brachiopod fauna throughout the entire Devonian section from the Silurian-Devonian boundary at the Podilla region to the Devonian-Carboniferous boundary at the SW slope of the Dnipro-Donets Depression (DDD). The Devonian brachiopods (mainly Productids, Spiriferids and Rhynchonellids) of the south-west segment of the East-European Platform (EEP) are reviewed from the DDD, Volhyn-Podilla monocline (VPM) including the L’viv Paleozoic Trough, and Fore-Dobrogea Paleozoic Depression (FDPD). The faunas of these regions are mutually related and compared to the Devonian faunas of the EEP (Russia) and Pripyat’ Depression (Belarus). In recent years several paleontological investigations have broadened and deepened our knowledge of the Devonian biostratigraphy of Ukraine. Based on systematic studies of brachiopods from the SW segment of the EEP we recognize four successive faunas corresponding to four great marine transgressions — Early Devonian (Tiwer Series, the Monograptus uniformis Zone), Middle Devonian (Givetian Stage, the conodont varcus Zone), Late Frasnian (the conodont Upper rhenana — linguiformis Zone), and Early Famennian (the conodont triangularis-crepida Zone). The Early Devonian association includes Howellella angustiplicata, Plectodonta maria, and Daiya navicula and others which are similar to late Silurian brachiopods by their generic features (represented the genus common with the Upper Silurian). The Middle Devonian assemblages contain: Emanuella volhynica, Atrypa (Desquamatia) ventricosa, Chonetes sarcinulata, and Poloniproductus productoides at VPM sections (Givetian Stage, the varcus Zone), as well as Variatrypa sokolovae (Eifelian Stage), but in the DDD sections the impoverished association with Stringocephalus cf. burtini (Eifelian Stage) and Atrypa uralica (Givetian Stage) occur. The Late Frasnian association is represented by dominance of Theodossia tanaica, T. evlanensis, T. livnensis at all regions — VPM, DDD and FDPD (the Upper rhenana — linguiformis zones). The Early Famennian association is represented by ex Cyrtospirifer archiaci = Cyrtospirifer asiaticus and Cyrtospirifer ljachovichensis, Cyrtiopsis sp., Ptychomaletoechia zadonica, Iloerhynchus tichomirovi, Ardiviscus ex gr.herminae, Steinhagella annae etc. at DDD and by the same association plus Dmitria angustirostris at VPM (the triangularis-crepida zones). Brachiopods near the D-C boundary have been recorded so far from the black shales fossiliferous deeper water facies only in DDD: Spinocarinifera nigra, S. fallax, Sphenospira julii, Parallelora sp. (the Siphonodella praesulcata Zone). The result of our systematic study of productids, spiriferids, rhynchonellids, atrypids, and athyrids from Ukrainian sections are in perfect agreement with, and supplement to the previous investigations of Middle and Upper Devonian deposits at VPM and DDD, suggesting their important role for precising boundaries between the Devonian stages and horizons in SW segment of EEP. The essential role of brachiopods for the Devonian biostratigraphy and correlations with the East-European biozonation is confirmed.

Morphometric variance, evolutionary constraints and their change through time in Late Devonian Palmatolepis conodonts.

Phenotypic variation is the raw material of evolution. Standing variation can facilitate response to selection along "lines of least evolutionary resistance", but selection itself might alter the structure of the variance. Shape was quantified using 2D geometric morphometrics in Palmatolepis conodonts through the Late Devonian period. Patterns of variance were characterized along the record by the variance-covariance matrix (P-matrix) and its first axis (Pmax). The Late Frasnian was marked by environmental oscillations culminating with the Frasnian/Famennian mass extinction. A shape response was associated with these fluctuations, together with a deflection of the Pmax and the P-matrix. Thereafter, along the Famennian, Palmatolepis mean shape shifted from broad elements with a large platform to slender elements devoid of platform. This shift in shape was associated with a reorientation of Pmax and the P-matrix, due to profound changes in the functioning of the elements selecting for new types of variants. Both cases provide empirical evidences that moving adaptive optimum can reorient phenotypic variation, boosting response to environmental changes. On such time scales, the question seems thus not to be whether the P-matrix is stable, but how it is varying in response to changes in selection regimes and shifts in adaptive optimum.

The upper devonian magmatic complexes of the South-East Belarus

For the first time, the authors determined lateral-temporal series of magmatic complexes of the Late Frasnian-Early Famennian Pripyat-Dnieper Magmatic Area according to the results of petrological and geochemical study of rocks of the Pripyat-Dnieper Magmatic Area (north-western part of the Pripyat-Dnieper-Donetsk Magmatic Province) in the southwest of the East European Platform using the principles of structural-material analysis and taking into account previous studies. The series consists of four complexes, formed during stages of magmatic activity, separated by time intervals: Zhlobin Complex (Rechitsa Time, the beginning of the Late Frasnian), Uvarovichi complex (Late Voronezh Time, the middle of the Late Frasnian), Pripyat Complex (Skolodin (Skolodin-Chernin?) Time, the end of the Late Frasnian) and Loev complex (Yelets (Yelets- Petrikov?) Time, Early Famennian). The rocks of the Zhlobin Complex belong to the alkaline-ultramafic (carbonatite-kimberlite-nephelinite) formation; Uvarovichi Complex - to the alkaline-mafic formation (basaltoids and phonolites); Pripyat Complex - to the alkaline-mafic-salic formation (trachyandesites); Loev Complex - to the alkaline-ultramafic (nepheline) formation.

Palynology and geochemistry of the Frasnian global transgression in the Parnaíba Basin, Brazil

An integrated palynological and geochemical approach has been initiated to date and to precise the geochemical events of the Pimenteiras Formation, in the Late Devonian from the Parnaíba Basin, Brazil. Based on good biostratigraphic markers and presence of index species among miospores, acritarchs and chitinozoa, the investigated sequences are referred to the Middle to early Late Frasnian. Among Miospores, Chelinospora concinna and Verrucosisporites bulliferus are likely to be from the BPi Interval Zone defined in the Amazon Basin. Chitinozoans of the Early to early Late Frasnian Angochitina (Lagenochitina) avelinoi zone of the Parnaíba Basin are present, and acritarch assemblages are also consistent with a Middle to early Late Frasnian age, by comparison to assemblages previously described in other Brazilian basins. Some important accompanying species of palynomorphs are illustrated. In the studied outcrops, black shale intervals are referred to top of the Radioactive Sale B and Radioactive Shale C according to Rodrigues (1995) definitions. Top of Radioactive Shale B shows good concentration of terrestrial organic matter, but low potential source of gas. By comparison Radioactive Shale C of the upper part of the Pimenteiras Formation, with important concentration of marine organic matter have low to high potential as source of gas and condensate. This study shows that a progressive flooding took place during the Devonian period in the Parnaíba Basin with maximum marine transgression in the Frasnian. These global events of interest for hydrocarbon exploration, are regarded as markers for Gondwanan regional chronostratigraphic correlations.

Geohistorical analysis of the northern part of the Pai-Khoi carbonate parautochthone in Late Devonian–Carboniferous

Research subject. This article focuses on the geological structure of the northern part of the Pai-Khoi carbonate parautochthone.Materials and methods. The study was based on the data obtained on the key sections of the North-Western Pai-Khoi. Research methods included lithological and facies analysis, subsidence curves, reconstruction of the thermal maturity of deposits based on conodont alteration indexes, X-ray microtomography for determining porosity values.Results. The Upper Devonian–Carboniferous succession (ca. 900 m thick) is composed of the terrigenous and carbonate Pyrkov Fm. (Frasnian), carbonate Lymbadyakha Fm. (Famennian-Tournaisian), Bolvanskii Fm. (Visean-Bashkirian), and Hoiponganase Fm. and Reef Chaika (Moskovian-Kasimovian). The early Frasnian part of the succession was deposited in a shallow-water environment. In the Middle–Late Frasnian, the Korotaikha paleodepression and an isolated carbonate platform was formed on the shelf edge. Filling of the paleodepression was completed at the end of the Early Visean. In the Late Visean–Late Carboniferous, a carbonate platform (ramp) formed. A Middle Paleozoic paleogeothermal gradient reconstructed on the basis of conodont alteration indexes is much higher in the Pai-Khoi carbonate parautochthone than in the most of Pechora Plate regions. This is likely to have been caused by the tectonic activity of the plate border in the Late Carboniferous–Mesozoic. A downward decrease in open porosity (from 6% to 0.1%) is likely to have been associated with increased compaction and recrystallization of the carbonates.Conclusions. Famennian-Tournaisian carbonate formations of the Pai-Khoi carbonate parautochthone were deposited under the conditions of isolated platform environment; however, the Visean–Late Carboniferous deposits were formed in the outer ramp environment. The Late Devonian–Middle Carboniferous carbonate deposits of the Pai-Khoi parautochthone demonstrate an extremely low open porosity and a high thermal maturity. These properties, along with the pronounced faulting and folding of the rocks, significantly decrease petroleum-bearing prospects of these deposits.

Size reduction of conodonts indicates high ecological stress during the late Frasnian under greenhouse climate conditions in South China

The Late Frasnian mass extinction (LFME) during extreme greenhouse conditions had a serious impact on biotic evolution. Herein, based on detailed size measurements of 1783 elements of the conodont genera Polygnathus and Palmatolepis at the Lali and Duan sections in South China, conodont animals underwent significant size reduction at the genus level during the late Frasnian. The “Bergmann's rule” controlled the evolution of Frasnian conodont animals, and their size reduction during the late Frasnian may have resulted from long-term global warming and indicated high ecological stress before the Frasnian-Famennian boundary (FFB). This phenomenon can explain why the decline of benthic faunas, such as corals, brachiopods or metazoan reefs, predated the extinction of pelagic faunas, such as conodonts in the Upper Kellwasser (UKW) event and at the FFB.

Organic facies and palynology from the middle to late Devonian of the Pimenteiras Formation, Parnaíba Basin, Brazil

A detailed study of organic facies and palynological assemblages was carried out on 11 samples of potential hydrocarbon source rocks of the Pimenteiras Formation, an outcropping at the western edge of the Parnaíba Basin, Brazil. The main objectives are to characterize the depositional paleoenvironment and hydrocarbon source potential. The selection of this outcrop occurred in the function of its preservation and accessibility, and the samples collection observed 1 m of vertical spacing. Generally, the organic matter and the palynomorphs showed a good state of preservation and fluorescence. The most notable spores and acritarchs and phycomates species were discussed in light of international biozones, and the chronostratigraphic range defined as Late Eifelian - Latest Frasnian in age. TOC results show ranges from 0.40 to 2.91%, with most samples showing greater than 1%, thereby holding a high potential generation. The S1 values were virtually null, and the S2 peak ranged from 0.9 to 5.33 mg/g. The kerogen 435 °C, and the ICE between 4.0 and 4.5 demonstrating the material immaturity. For the palynofacies associations definition, only 10 out of the 25 total quantified of subgroups of kerogen categories were considered in the counting of 300 particles. A dendrogram constructed based on these results through cluster analysis, revealed four palynofacies, as follows: I constituted mainly by palynomorphs (acritarchs, prasinophytes and sporomorphs); II – Dominance of Translucent organic matter (cuticles, epidermal tissue and translucent phytoclasts with and without structure); III - Dominance of Opaque/non-fluorescent (opaque phytoclasts and non-fluorescent AOM) and IV - Dominance of AOM fluorescent (amorphous organic matter with fluorescence). The palynomorphs are the most abundant constituents of all studied kerogen. Quantitative analysis based on the distribution of palynomorphs groups throughout the section indicates the dominance of sporomorphs in the palynological assemblages from the Middle Devonian aged samples. On the other hand, occurred the predominance of microplankton elements in the Late Devonian aged samples. Thus, the depositional paleoenvironment was established as a distal oxic mud-dominated shelf with the deltaic influence of the Late Eifelian to Late Givetian, and there is a tendency distal (dysoxic-anoxic ‘shelf’) from the Frasnian, which indicates the maximum flooding surface.

Cyclostratigraphic calibration of the Famennian stage (Late Devonian, Illinois Basin, USA)

The Late Devonian biosphere was affected by two of the most severe biodiversity crises in Earth's history, the Kellwasser and Hangenberg events near the Frasnian–Famennian (F–F) and the Devonian–Carboniferous (D–C) boundaries, respectively. Current hypotheses for the causes of the Late Devonian extinctions are focused on climate changes and associated ocean anoxia. Testing these hypotheses has been impeded by a lack of sufficient temporal resolution in paleobiological, tectonic and climate proxy records. While there have been recent advances in astronomical calibration that have improved the accuracy of the Frasnian time scale and part of the Famennian, the time duration of the entire Famennian Stage remains poorly constrained. During the Late Devonian, a complete Late Frasnian–Early Carboniferous succession of deep-shelf deposits accumulated in the epieric sea in Illinois Basin of the central North-American mid-continent. A record of this sequence is captured in three overlapping cores (H-30, Sullivan and H-32). The H-30 core section spans the F–F boundary; the Sullivan section spans almost all of the Famennian and the H-32 section sampled spans the interval of the Upper Famennian and the D–C boundary. To have the best chance of capturing Milankovitch cycles, 2000 rock samples were collected at minimum 5-cm-interval across the entire sequence. Magnetic susceptibility (MS) was measured on each sample and the preservation of climatic information into the MS signal was verified through geochemical analyses and low-temperature magnetic susceptibility acquisition. To estimate the duration of the Famennian Stage, we applied multiple spectral techniques and tuned the MS signal using the highly stable 405 kyr cycle for Sullivan and the obliquity cycle for the H-30 and H-32 cores. Based on the correlation between the cores we constructed a Famennian floating astronomical time scale, which indicates a duration of 13.5 ± 0.5 myr. An uncertainty of 0.5 myr was estimated for the uncertainties arising from the errors in the stratigraphic position of the F–F and D–C boundaries, and the 405 kyr cycle counting. Interpolated from the high-resolution U–Pb radiometric ages available for the Devonian–Carboniferous boundary we recalibrated the Frasnian–Famennian boundary numerical age to 372.4 ± 0.9 Ma.

Late Devonian and Early Carboniferous alpha diversity, ecospace occupation, vertebrate assemblages and bio-events of southeastern Morocco

The Late Devonian was a time of dramatic environmental perturbations affecting marine ecosystems. Both the Kellwasser (latest Frasnian) and the Hangenberg crises (latest Famennian) are primarily reported as phases of drastic decreases in marine diversity while the Hangenberg Crisis is also described as a bottleneck in vertebrate evolution. Fossil-bearing localities with Upper Devonian strata are of great interest to assess variations in the effects of environmental perturbations on biodiversity. For this purpose, we examined changes in alpha diversity and ecospace utilization of 21 Famennian (Late Devonian) and early Tournaisian (Early Carboniferous) invertebrate associations containing 9828 specimens from Madène el Mrakib and Aguelmous (southern Maïder Basin, northeastern Anti-Atlas, Morocco), where some layers yield exceptionally preserved gnathostome remains. Both the invertebrate and vertebrate associations contain predominantly opportunistic and pelagic taxa indicating oxygen depletion near the seafloor in this region. Nevertheless, the ecospace extension was fluctuating and correlated with regional and/or global sea-level changes and oxygenation of bottom waters. In the Maïder Basin, the ecospace was depleted after and during several bio-events such as the Kellwasser and Hangenberg crises, the Annulata event (middle Famennian) as well as during the early Tournaisian. Abiotic as well as biotic changes (instability of the invertebrate ecosystem) are considered to have influenced Famennian vertebrate diversity because they were more or less directly dependent on invertebrates as a food source.

Tabulate corals across the Frasnian/Famennian boundary: architectural turnover and its possible relation to ancient photosymbiosis

The Frasnian-Famennian biodiversity crisis has traditionally been considered one of the “Big Five” mass extinctions; among deep changes in the biosphere, it almost completely erased shallow-water marine ecosystems like coral-stromatoporoid reefs, which were widespread on the carbonate platforms in the Devonian. The high biodiversity of bioconstructors during the Givetian-Frasnian acme of Palaeozoic reef development contrasts sharply with very low biodiversity levels during the Famennian. One of major bioconstructing groups in the Palaeozoic was tabulate corals. A statistical analysis of colony architecture of Givetian-Frasnian and Famennian tabulates from the Holy Cross Mountains (Poland) reveals that Givetian and Frasnian tabulate faunas had smaller corallite diameters and higher colony integration, compared to the Famennian faunas. A similar pattern occurs in the Devonian of the Ardennes. In the Holy Cross Mountains the biodiversity drastically decreases in the Late Frasnian. We interpret Givetian-Frasnian tabulate communities as generally photosymbiotic, and their Famennian counterparts as generally aposymbiotic. In Recent corals temperatures above 32°C are generally considered as a threshold for bleaching (expulsion of photosymbionts), a literature review indicates that in the late Frasnian sea surface temperatures exceeded this threshold. This leads to a discussion of the late Frasnian rise of temperature as a contributing cause of extinction of photosymbiotic bioconstructors, and possibility of a Late Devonian “bleaching event”.

Corrigendum

LethaiaVolume 50, Issue 4 p. 591-591 CorrigendumFree Access Corrigendum This article corrects the following: Depositional conditions during the Lower Kellwasser Event (Late Frasnian) in the deep-shelf Łysogóry Basin of the Holy Cross Mountains Poland Michał Rakociński, Agnieszka Pisarzowska, Katarzyna Janiszewska, Piotr Szrek, Volume 49Issue 4Lethaia pages: 571-590 First Published online: March 25, 2016 First published: 13 September 2017 https://doi.org/10.1111/let.12215AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat In the article by Rakociński et al. (2016) entitled ‘Depositional conditions during the Lower Kellwasser Event (Late Frasnian) in the deep-shelf Łysogóry Basin of the Holy Cross Mountains Poland’, the author provided Figure 3 with the wrong conodonts on position T and U (page 575) during the production stage. The correct figure is reproduced below. Figure 3Open in figure viewerPowerPoint Conodonts from Płucki village section. A. Ancyrodella lobata; sample PW 3; B–D. Ancyrodella nodosa; B – sample PW 10; C – sample PW 7; D – sample PW 5; E–H. Ancyrognathus triangularis – sample PW 5; I, J. Icriodus alternatus alternatus Branson et Mehl; I – sample PW 3; J – sample PW 5; K–M. Icriodus symmetricus; K – sample PW 10; L – sample PW 7; M – sample PW 5; N. Palmatolepis bogartensis; sample PW 10; O, P. Palmatolepis hassi Müller et Müller; O – sample PW 7; P – sample PW 10; R, S. Palmatolepis winchelli; sample PW 7; T. Polygnathus webbi Stauffer; sample PW 7; U. Polygnathus procerus; sample PW 5. The author apologizes for this error in the originally published version. Reference Rakociński, M., Pisarzowska, A., Janiszewska, K. & Szrek, P. 2016: Depositional conditions during the Lower Kellwasser Event (Late Frasnian) in the deep-shelf Łysogóry Basin of the Holy Cross Mountains Poland. Lethaia 49, 571– 590. Volume50, Issue4October 2017Pages 591-591 FiguresReferencesRelatedInformation

Assessment of nutrition status in patients with pancreatic exocrine insufficiency in pancreatic diseases

The Frasnian-Famennian biodiversity crisis has traditionally been considered one of the “Big Five” mass extinctions; among deep changes in the biosphere, it almost completely erased shallow-water marine ecosystems like coral-stromatoporoid reefs, which were widespread on the carbonate platforms in the Devonian. The high biodiversity of bioconstructors during the Givetian-Frasnian acme of Palaeozoic reef development contrasts sharply with very low biodiversity levels during the Famennian. One of major bioconstructing groups in the Palaeozoic was tabulate corals. A statistical analysis of colony architecture of Givetian-Frasnian and Famennian tabulates from the Holy Cross Mountains (Poland) reveals that Givetian and Frasnian tabulate faunas had smaller corallite diameters and higher colony integration, compared to the Famennian faunas. A similar pattern occurs in the Devonian of the Ardennes. In the Holy Cross Mountains the biodiversity drastically decreases in the Late Frasnian. We interpret Givetian-Frasnian tabulate communities as generally photosymbiotic, and their Famennian counterparts as generally aposymbiotic. In Recent corals temperatures above 32 °C are generally considered as a threshold for bleaching (expulsion of photosymbionts), a literature review indicates that in the late Frasnian sea surface temperatures exceeded this threshold. This leads to a discussion of the late Frasnian rise of temperature as a contributing cause of extinction of photosymbiotic bioconstructors, and possibility of a Late Devonian “bleaching event”.

Late Devonian dimpled phosphatic microspherules associated with conodonts are possible otoliths of short-lived and opportunistic organisms

Dimpled phosphatic microspherules, contradictorily associated with conodonts, are widely distributed in strata ranging in age from the Cambrian to Carboniferous. These microspherules have attracted much attention from palaeobiologists and were suggested to be ‘conodont pearls’, ‘conodont otoliths’ or ‘fish otoliths’ due to their similar chemical composition and co-occurrence with conodonts or fish teeth. However, these hypotheses are still highly controversial. Here, we report ‘checks’, ‘rhythmic growth patterns’ and ‘sub-diurnal increments’ from growth annuli of the Late Devonian phosphatic microspherules from South China, on the basis of quantitative microstructure analysis. The annulus width of phosphatic microspherules becomes narrower with increasing radius. These microstructural characteristics of growth annuli are most typical indicators of modern animal otoliths. In addition, a maximum value of about 90 annuli is encountered from all the specimens. We propose that these microspherules are essentially phosphatic otoliths, which might have been secreted by a specific kind of marine organisms with very short lifespans (less than 90 days). Furthermore, the sudden enrichment of phosphatic microspherules in the late Frasnian may represent a biological response of short-lived animals to ecological crisis such as ocean eutrophication.

Conodont biostratigraphy and palaeoenvironmental trends during the Famennian (Late Devonian) in the Thuringian Buschteich section (Germany)

This study characterizes the stratigraphical context as well as the palaeoenvironmental and sea-level trends during the Late Frasnian and Famennian in the Buschteich section (Thuringia, Germany). An integrated approach combines conodont biostratigraphy, chemostratigraphy based on carbon and oxygen isotopes , conodont biofacies analyses and investigations of the morphotypes of foraminifera that occur in the section was applied. Conodonts provided a fine-scale biostratigraphical framework. All the Famennian con-odont biozones were identified, with the exception of the three lowest. The Frasnian-Famennian transition was further identified by a positive carbon isotope excursion. This continuous Famennian record is developed in a condensed limestone succession. The reddish Griotte facies, typical of strata of this period, were not documented. Black shales were not developed except for an interval of dark colored mud rocks corresponding to the Hangenberg event at the top of the section. The carbonate succession of Buschteich was deposited in an outer ramp environment, pelagic organisms are the dominant fauna. This is corroborated by the overall dominance of the deep-water conodont genus Palmatolepis. Microfacies, conodont biofacies and foramini-fera indicated a deepening trend from the Lower crepida to the Lower rhomboidea Zone, followed by a shal-lowing trend from the Upper rhomboidea to the praesulcata Zone. This sequence overall matches the sea level reference curve for Euramerica. The timing of maximum water depth at Buschteich, as well as the general sea-level reference record, differs from the Col des Tribes (Montagne Noire, France). Differential uplift or overprinting of the long-term eustatic changes may be the cause of the discrepancy in the local sea-level records.