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Early-Middle Frasnian transition: Biotic response to a major perturbation of the global carbon budget

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Balinski A., Olempska E., Racki G.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

606-608

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Early-Middle Frasnian cyrtospiriferid brachiopods from the East European Platform

72%

Sokiran E. V.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

759-772

The cyrtospiriferids are among the most important fossils in the Frasnian strata of the East European Platform (EEP). During the Early Frasnian (Palmatolepis falsiovalis Zone) the numerous and morphologically distinct Uchtospiriferinae, accompanied by very scarce Cyrtospiriferinae, are known from South Timan. The mass appearance of cyrtospiriferins on the platform at the beginning of the Middle Frasnian is linked with significant sea−level rise of Devonian Transgression−Regression (T−R) cycle IIc. At that interval these brachiopods attain their highest diversity of the entire Frasnian. The Early Frasnian type species of the genus Uchtospirifer is here revised, and subfamily Uchtospiriferinae re−established. Cyrtospirifer schelonicus, C. rudkinensis, C. mylaensis sp. nov., and C. tenticulum are described from the Middle Frasnian of NW and central regions of EEP and Middle Timan.

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Faunal and facies changes at the Early-Middle Frasnian boundary in the north-western East European platform

72%

Zhuravlev A. V., Sokiran E. V., Evdokimova I. O., Dorofeeva L. A., Rusetskaya G. A., Malkowski K.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

747-758

Multidisciplinary study of the Early–Middle Frasnian boundary in the north−western East European Platform (Main Devonian Field) allows evaluation of changes in facies, brachiopod, ostracod, and conodont associations, as well as carbon isotope composition. Brachiopod and ostracod faunas, characterized by predominance of rhynchonellids, spiriferids, podocopids, and platycopids in the Early Frasnian, and by predominance of spiriferids, palaeocopids, and kloedenellocopids in the Middle Frasinan, demonstrate significant changes in dominance and diversity likely caused by regressiontransgression couplets in the extremely shallow−water environment. Changes in diversity of the conodont associations, represented mainly by shallow−water polygnathids and spathognathids, are controlled by sea−level fluctuations as well; however significant evolutionary turnover is absent. Deepening pulses lead to an increasing in diversity of both the benthic and nectic groups, whilst regressions cause diversity fall due to progressive habitat reduction. Most prominent decreasing in the fauna diversity is observed in the late Early Frasnian (Dubnik time) coinciding with the regressive phase of the Late Givetian to Early Frasnian eustatic cycle. Positive−negative δ¹³C excursion, detected in brachiopod calcite from the early interval of the Middle Frasnian, can be correlated with global isotopic perturbations near the Frasnian substage boundary: the positive 2.6‰ δ¹³C excursion is probably linked with enhanced primary production in high−nutrient regimes in the epeiric sea.

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Benthic ostracods from the Early-Middle Frasnian transition in the north-western East European Platform, Russia

72%

Evdokimova I. O.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

773-778

Pronounced changes in benthic ostracod associations in the north−west part of the East European Platform, across the Early–Middle Frasnian (Devonian) transition, track a marine transgression event. More than 80 ostracod species belonging to the Eifelian Mega−Assemblage were recorded. Cavellinidae and Acratiidae generally dominate the Early Frasnian Sargaevo Horizon. Middle Frasnian ostracod associations of the Semiluki Horizon are more diverse and are characterised by different dominant both geographically and stratigraphically, resulting from significant palaeo−basin bottom relief and benthic biotope differentiation. The ostracod associations are indicative of very shallow, well oxygenated semi−restricted epeiric environment, with occasional marine influence, alternating with short periods of open shelf conditions. The relative abundance of ostracod species in the different associations, and faunal diversity indices, show considerable variations throughout the Early–Middle Frasnian, and suggest a less restricted position within an intra−platform setting in the Middle Frasnian, relative to a more restricted ostracod habitat in the Early Frasnian. The succession of Early–Middle Frasnian micro−benthic associations within the Main Devonian Field seems to be of a regional scale, and resulted from a marine regression−transgression couplet, corresponding to eustatic cycles IIb–IIc. This was paired with synsedimentary tectonic subsidence in adjacent areas of the north−east East European Platform, progressively improving marine water circulation in the extremely shallow−water shelf seas.

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Gastropod succession across the Early-Middle Frasnian transition in the Holy Cross Mountains, southern Poland

58%

Krawczynski W.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

679-693

Gastropod response to a marked carbon isotopic geochemical anomaly across the Early–Middle Frasnian transition (Palmatolepis transitans–Palmatolepis punctata conodont zones) has been analysed along the southern Laurussian shelf, mainly within the Dyminy Reef in the Holy Cross Mountains. Gastropods are represented by three reefal associations (Kowalatrochus sanctacrucensis, Euryzone kielcensis, and Grabinopsis guerichi associations), and an impoverished open−shelf Straparollus laevis assemblage. The most severe diversity crisis is connected to the disappearance of local low−energy muddy habitats, as a result of a transgressive pulse (Middlesex Event) and benthic habitat changes tied to strongly fluctuating carbon cycling; this has been observed at the highly diverse Kadzielnia−type assemblage. Fifteen taxa have been recognised in this distinctive Early Frasnian mud−mound association, including six (probably endemics), which are unknown from the Middle Frasnian. The disappearance of three relict Givetian species (Euryzone delphinuloides, Straparollus laevis, and Goniasma? zarecznyi) is also recorded. Other species probably migrated into the shallower water part of Dyminy Reef and persisted in the Middle and Late Frasnian. The Middlesex Event and the earlier major biogeochemical perturbation seem to have less serious effects for evolution of gastropods in the Polish−Moravian part of the Laurussia shelf than the catastrophic Frasnian–Famennian extinction. Two new taxa are described: Frydiella kaimi gen. et sp. nov. (Eotomariidae) and Heidelbergeria czarnieckii gen. et sp. nov. (Elasmonematidae).

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Conodont ecology in the Early-Middle Frasnian transition on the South Polish carbonate shelf

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Sobstel M., Makowska-Haftka M., Racki G.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

719-746

Well exposed Early–Middle Frasnian (E–MF, Palmatolepis transitans to Palmatolepis punctata zonal interval) deposits of the Holy Cross Mountains, in particular the reference Wietrznia section at Kielce, were studied in terms of conodont biofacies dynamics. Frequency of the conodont elements has been controlled mostly by depositional rate in hemipelagic muddy lithofacies and post−mortem gravity sorting during lateral redeposition in storm−generated, talus−like and encrinite layers. The conodont assemblages are dominated by a highly varying proportion of polygnathid, icriodontid, and ancyrodellid fauna. Major biofacies turnovers coincided with the deepening pulses corresponding to Timan, Middlesex, and early Rhinestreet global events. Trends in the conodont dynamics, mortality, and diversity point that the biotic shifts also coincide with the large−scale δ¹³C excursions as a record of changing trophic conditions during the major biogeochemical perturbation. A gradual decline of the Early Frasnian Ancyrodella reef−dwelling community correlates with the minor positive and succeeding larger negative δ¹³C excursion, and this is paired with a replacement by, mostly sparse, polygnathid and polygnathid−icriodontid biofacies, as well as with a short−term Belodella acme in mud−mounds areas. The distinctive habitat deterioration in pelagic and reef ecosystems is broadly correlative with the Domanik Crisis. The progressive biofacies unification is a conodont response to onset of the prolonged (ca. 0.5 Ma) δ¹³C enrichment, probably linked with high−stress life conditions due to eutrophication and partly anoxic regimes. A negative carbon isotope excursion in the late Pamatolepis punctata Zone is marked by the second major biofacies turning point during the Rhinestreet transgression, as recorded primarily in a final mesotaxid extinction, and highlighted also by decrease of conodont size and increased mortality of juveniles. After stabilization of δ¹³C values and a return to the background level across the Palmatolepis punctata–Palmatolepis hassi zonal transition, renewed biofacies diversification, in particular re−appearance of reef−related ancyrodellid fauna, took place. In addition, a large−scale migration event among palmatolepids and polygnathids during sea−level rise, mainly from the East European Platform, characterised this Middle Frasnian interval.

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Brachiopods and their response to the Early-Middle Frasnian biogeochemical perturbations on the South Polish carbonate shelf

58%

Balinski A.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

647-678

The brachiopod faunas from deposits recording the Early–Middle Frasnian transition of Poland are poorly known. The present report describes these faunas that were recovered from Wietrznia and Kostomłoty (Holy Cross Mountains) and Dębnik (Silesian−Cracow Upland) regions positioned on the southern Polish carbonate shelf. The brachiopod distribution was analysed relative to a significant δ¹³C excursion, referred recently to as Palmatolepis punctata Event. The sporadic occurrence of brachiopods at Dębnik makes it difficult to analyse the biotic response to this geochemical anomaly. However, higher brachiopod frequency in the topmost part of the section coincides with a gradual decrease of δ¹³C down to the Frasnian background values. At two studied sections at Wietrznia the greatest taxonomic diversity and abundance of brachiopods (Flabellulirostrum–Coeloterorhynchus assemblage) are confined to the Palmatolepis transitans Zone. In the following Pa. punctata Zone brachiopods are rare (Biernatella lentiformis assemblage) or absent, which suggests a serious deterioration of the environmental conditions linked probably with periods of benthic anoxia−dysoxia and oligotrophic conditions in the basin. In two Kostomłoty sections brachiopods faunas of this age are members of the mostly monospecific rhynchonellid−dominated Phlogoiderhynchus polonicus assemblage which inhabited deeper−water environments characteristic of intrashelf oxygen−depleted basins of ŁysogóryKostomłoty region. In some horizons large shells of P. polonicus were frequently colonised by discinoid Romerella? sp. Among 28 species described in this report new forms include: Flabellulirostrum kielcensis sp. nov., F. rackii sp. nov., and Thomasaria ventosa sp. nov.

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Conodont-based event stratigraphy of the Early-Middle Frasnian transition on the South Polish carbonate shelf

58%

Pisarzowska A., Sobstel M., Racki G.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

609-646

Early to Middle Frasnian (E–MF) epicontinental sequences are investigated in five representative localities of the Holy Cross Mountains and Cracow region, with emphasis on conodont biostratigraphy, to evaluate the regional stratigraphic and biotic context of a major biogeochemical perturbation in global carbon cycling. Conodont associations from the Palmatolepis transitans to Palmatolepis punctata Zone boundary beds are dominated by the shallow−water polygnathid and ancyrodellid fauna in the South Polish epicontinental successions, and first appearances of index palmatolepid species are delayed due to facies control of pelagic environments during intermittent drowning of the carbonate shelf. Thus, identification of the zonal boundary is based mainly on species of Ancyrodella, and five distinctive ancyrodellid levels in the succession across the E–MF interval enable refined correlation of the sections studied, especially when paired with chemostratigraphic proxies. Prominent conodont biofacies shifts coincided with eustatic deepening, which is correlated with the Timan, Middlesex, and early Rhinestreet events, respectively. Trends in the conodont dynamics, mortality and diversity, partly replicated by the benthic biota (especially shelly faunas and crinoids), indicate that the faunal turnovers correlate also with the main δ¹³C excursions and related changes in trophic conditions. The E–MF transitional interval, marked by short−term sea−level fluctuations, is distinguished by a change from relatively diversified biofacies to more homogenous, mostly impoverished faunas. The latter change is a biotic response to the beginning of a prolonged (ca. 0.5 Ma) positive δ¹³C anomaly, probably paired with unsteady eutrophic and partly anoxic regimes. The late Pa. punctata Zone negative carbon isotope anomaly is synchronous with the second large−scale pelagic biofacies remodelling, including mesotaxid extinction. A stabilization of the carbon cycle and its return to normal background values at the start of the Early Palmatolepis hassi Zone coincide with conodont biofacies diversification and recovery of reef−related biofacies. With the exception of collapsed, endemic Kadzielnia−type mud−mound biota and a moderate biodiversity depletion due to overall ecosystem stagnation, no significant extinction events can be demonstrated, even if the large−scale changes in carbon cycling during the E–MF timespan are of higher−amplitude than the celebrated carbon isotopic anomalies related to the Frasnian–Famennian mass extinction. Thus, this regional succession in detail confirms that the large−scale punctata Isotopic Event (= Pa. punctata Event) is correlated neither with catastrophic enviromental nor radical biotic changes.

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Crinoid and ostracod succesion within the Early-Middle Frasnian interval in the Wietrznia quarry, Holy Cross Mountains, Poland

58%

Gluchowski E., Casier J. G., Olempska E.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 4

695-706

Early–Middle Frasnian ostracods and crinoids from Wietrznia in the Northern Kielce subregion of the Holy Cross area were analyzed. Twenty three ostracod species assigned to thirteen named genera, as well as eighteen crinoid species including the representatives of fifteen stem−based taxa were distinguished. For most of the species open nomenclature is applied. The composition of ostracod assemblage changes from moderately diverse in the lower part of the Palmatolepis transitans Zone to poorly diverse in its higher part. Lack of ostracods in the uppermost part of the Pa. transitans Zone and in the Palmatolepis punctata Zone is noted. The crinoid distribution pattern comprises the interval of relatively high diversity, interrupted in the uppermost part of the Pa. transitans Zone, and the interval of temporary recovery in the lower Pa. punctata Zone. Such distribution patterns point to deterioration of environmental conditions across the Early–Middle Frasnian transition, coinciding with a large−scale C−isotopic perturbation superimposed on intermittent, two−step eustatic sea level rise. On the other hand, impoverished, surviving crinoid faunas and absence of ostracods in the Pa. punctata Zone indicate the overall long−term deterioration of life conditions through the major C−isotope anomaly time span. However, this may also result from synsedimentary tectonic pulses, causing block movements and large−scale resedimentation phenomena on the northern slope of the Dyminy Reef during the basal Middle Frasnian sea level rise.

Ograniczanie wyników

9 Acta Palaeontologica Polonica

3 Racki G.

2 Balinski A.

2 Evdokimova I. O.

2 Olempska E.

2 Sobstel M.

2 Sokiran E. V.

1 Casier J. G.

1 Dorofeeva L. A.

1 Gluchowski E.

1 Krawczynski W.

1 Makowska-Haftka M.

1 Malkowski K.

1 Pisarzowska A.

1 Rusetskaya G. A.

1 Zhuravlev A. V.

9 2006

Early-Middle Frasnian transition: Biotic response to a major perturbation of the global carbon budget

Early-Middle Frasnian cyrtospiriferid brachiopods from the East European Platform

Faunal and facies changes at the Early-Middle Frasnian boundary in the north-western East European platform

Benthic ostracods from the Early-Middle Frasnian transition in the north-western East European Platform, Russia

Gastropod succession across the Early-Middle Frasnian transition in the Holy Cross Mountains, southern Poland

Conodont ecology in the Early-Middle Frasnian transition on the South Polish carbonate shelf

Brachiopods and their response to the Early-Middle Frasnian biogeochemical perturbations on the South Polish carbonate shelf

Conodont-based event stratigraphy of the Early-Middle Frasnian transition on the South Polish carbonate shelf

Crinoid and ostracod succesion within the Early-Middle Frasnian interval in the Wietrznia quarry, Holy Cross Mountains, Poland