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The Komstad Limestone is composed of dark grey to black micritic limestone deposited in an outer shelf environment on the margin of the East European Platform. It represents an interval of low sea level during the late Volkhov to early Kunda that led to the spread of limestones into the shale-dominated western lithofacies belt. The Baltoniodus norr...
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Citations
... 14). Nordiora has previously been described from Baltic sections facing the Iapetus Ocean and the Tornquist Sea (Rasmussen, 2001;Stouge and Nielsen, 2003;Dzik, 1978-see Rasmussen and Stouge, 2018 for synonymy) but is considered temperature dependent, favouring cool conditions on the relatively distal and deep mid-shelf areas (Rasmussen and Stouge, 2018). However, it has also been observed previously from the relatively shallower Amdeh 5 Member by Miller et al. (2018, as aff. ...
New trilobite material and the first graptolites from outcrop are described from the Am5 member of the Amdeh Formation near Al Fleij in northeast Oman. The sediments in which these faunas occur are interpreted as distal shelf deposits with storm beds packed with brachiopods and orthoconic nautiloids. The deposits and its faunas are considered of late Darriwilian age and younger than the shallower-water Am5 deposits known from other
outcrops. No palynomorphs could be recovered to confirm this due to the increased burial temperature the Al Fleij area has experienced.
The trilobites are of considerable palaeo-biogeographic interest as few faunas of this age are known from the Arabian Plate, though their preservation precludes the establishment of new species. They include Isabelinia aff. glabrata, Liomegalaspides sp., Neseuretus tristani, Neseuretinus sp. and the deeper-water forms, Cyclopyge cf. C. bohemica, Arthrorhachis sp. and Brachypleura sp. The graptolites are pendent Didymograptus spp. of later Darriwilian type.
Rare elements of the conodonts Nordiora, Amorphognathus and Microzarkodina have been recovered from shell beds that occur interbedded with the faunas. They too indicate a late Darriwilian age and differ from richer, restricted, shallow-water faunas known from the Am5 at other locations, and the more cosmopolitan shelf fauna from the Ayim Member of the Rann Formation of the United Arab Emirates.
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... Range and biodiversity data for conodonts in the Fågelsång section, Scania(Stouge and Nielsen 2003). Time of L-chondrite parent body breakup (LCPB) = dashed grey line. ...
... The latter authors correlated this level with the Darriwilian Levisograptus sinicus Zone. The limestone at locality E22 was correlated with the Lenodus antivariabilis conodont Zone by Stouge & Nielsen (2003). Compare also with the graptolite zonation of the Tøyen Formation below the Komstad Limestone and equivalent levels in the Krapperup, Albjära and Lovisefred cores, Skåne Maletz & Ahlberg 2021), where graptolites indicative of stage slices Dw1 and Dw2 are recorded. ...
... The upper part of the Huk and Stein formations in the Oslo Region, as well as the upper part of the Komstad Limestone in Skåne-Bornholm, correlate with the Kundan Stage ( Figure 5) Stouge & Nielsen 2003;. The Kundan upper part of the Lysaker Member, Huk Formation, is 1.9 m thick at Slemmestad , the overlying Svartodden Member is up to 2.7 m thick in the Oslo-Asker district , the Kundan part of the Stein Limestone is c. 25 m and the Kundan part of the Komstad Limestone is probably 7-8 m thick in SE Skåne . ...
The Ordovician of Scandinavia (i.e. Denmark, Norway and Sweden) have been investigated for over two centuries, and through time various chronostratigraphic schemes have been introduced, facilitating regional correlation. However, a modern chronostratigraphy has never been proposed. Here, we delineate ten regional stages for the Ordovician of Scandinavia, comprising, in ascending order, the Slemmestadian, Ottenbyan, Billingenian, Volkhovian, Kundan, Segerstadian, Dalbyan, Moldåan, Jerrestadian and Tommarpian. We propose to discontinue the use of the term Hunnebergian Regional Stage despite its Scandinavian origin; this interval is included in the new Ottenbyan Stage. The base of each stage, as (re)defined here, is selected to coincide with the appearance of a characteristic fossil taxon and delimited at the top by the base of the overlying stage. The stage boundaries generally coincide with or approximate to significant changes in the depositional environment that are recognizable across Scandinavia from the carbonate platform to the foreland basin. Local efficacy has been the primary criterion for the recognition of Scandinavian stage boundaries rather than approximating to the global or East Baltic stage boundaries. It is proposed to abolish the Baltoscandian regional series and subseries, as correlation with the global series are sufficiently precise to make these higher rank regional schemes redundant.
... Although these three beds are not recognized as discrete bentonite horizons, zircons from the beds show no signs of transport abrasion and share common features with elongated acicular morphologies, typical of zircons from volcanic ash or tuff due to rapid crystallization and a mode of air transport (Corfu et al., 2003;Galeotti et al., 2019). We therefore endorse the interpretation of that the zircons are products of distal volcanic ash falls related to active volcanism, which is known to have occurred in nearby southern Scania during the Middle Ordovician (Stouge and Nielsen, 2003). ...
The breakup of the L-chondrite parent body (LCPB) in the mid-Ordovician is the largest documented asteroid breakup event during the past 3 Gyr. It affected Earth by a dramatic increase in the flux of L-chondritic material and left prominent traces in both meteorite and sedimentary records. A precise constraint on the timing of the LCPB breakup is important when evaluating the terrestrial biotic and climatic effects of the event, as well as for global stratigraphic correlations. Direct dating using heavily shocked L chondrites is hampered by both incomplete initial K-Ar degassing and isotopic resetting by later impact events. In order to better constrain the absolute age of this event we carried out high-precision U–Pb dating of zircons from three limestone beds recording discrete volcanic ash fallouts within mid-Ordovician strata in southern Sweden. These strata are rich in fossilized L-chondritic meteorites (1-20 cm large) that arrived on Earth shortly after the breakup event. Zircons from the ash-bearing layers provide stratigraphically consistent depositional ages that range from 464.22 ± 0.37 Ma to 465.01 ± 0.26 Ma. Combined with recently published ³He profiles that pinpoint the arrival on Earth of the first dust from the breakup, and sedimentation rates constrained by cosmogenic ²¹Ne in the fossil meteorites, the LCPB breakup is estimated to have occurred at 465.76 ± 0.30 Ma. This provides the presently most precise absolute dating of the LCPB breakup, enabling a robust global stratigraphic correlation of bounding strata. Based on our new U–Pb data for the ash-bearing beds, the absolute ages for the boundaries of biozones and Dapingian–Floian stages overlap within error with those given by the 2012 Geological Timescale and require no modification.
... In view of this fact, we propose to include this species in the genus Lenodus. This assignation has been suggested by several authors before (Stouge and Bagnoli 1990;Löfgren and Zhang 2003;Stouge and Nielsen 2003;Schmitz et al. 2008;Melgren et al. 2012;Kröger and Rasmussen 2014). ...
A taxonomic review study on the apparatuses of the lower-middle Darriwilian index conodonts, based on the collections from the Precordillera and those described and illustrated in worldwide literature, had led to a new interpretation of the Lenodus apparatus composition. This apparatus is composed of pectiniform elements without mirror symmetry (Pa and Pb elements) with pastiniscaphate morphology and sometimes showing a micropattern structure (honeycomb) on the platform surface. The transitional series of S elements present the elements alate Sa, tertiopedate Sb, bipennate Sc, and quadriramate Sd with wartlike extensions on the tip of the cusps, and the M elements have a modified “geniculate” morphology. The analysis of the apparatuses of the Darriwilian index conodonts allows us to interpret that the genus Lenodus includes the following species: Lenodus variabilis, Lenodus crassus, Lenodus pseudoplanus, and Lenodus suecicus. This proposal is supported by the apparatus architecture, the transitional morphological features of the P elements, and the micropattern structure on the P and S elements present in all these species.
... It has been suggested that the marl beds are related to volcanism, as is perhaps also the case for the ferruginous debris found in this interval (see Sturesson et al. 1999;Sturesson 2003). Volcanically derived deposits occur in coeval strata at least in Sweden (e.g., Bergström 1989;Stouge & Nielsen 2003;). The many hardgrounds and stained skeletal grains in the uppermost Lynna Formation and basal Sillaoru Formation indicate severe sedimentary condensation (sensu Föllmi 2016) of this part of the rock succession, which may help to explain the exceptional amounts of extraterrestrial chromite and other heavy minerals found in these beds as compared to correlative beds at other localities (see Lindskog et al. 2012). ...
... This is in good agreement with the zonal relationship in coeval sections across Baltica, but it can be noted that it varies slightly between localities. For example, at Slemmestad, Oslo region, Norway, the base of the L. variabilis Zone was placed c. 50 cm below the base of the A. expansus Zone (Rasmussen 1991;Nielsen 1995;Rasmussen et al. 2013), at Lanna, Närke, Sweden, it is c. 30 cm below (Löfgren 1995;Lindskog et al. 2018) and at Fågelsång, Scania, Sweden, it is c. 10 cm below (Stouge & Nielsen 2003). In several other localities, the base of the L. variabilis Zone closely overlies the base of the A. expansus Zone. ...
... The close coincidence between the base of the Y. crassus conodont Zone and that of the A. raniceps trilobite Zone is similar to what is seen in other places regionally; however, as is the case for the A. expansus and L. variabilis zones, the relative positions of the boundaries may vary slightly between localities (e.g., Nielsen 1995;Zhang 1997;Villumsen et al. 2001;Stouge & Nielsen 2003;Wu et al. 2018). The species Y. crassus appears to be somewhat problematic to use for detailed correlations between localities, both within Baltoscandia and else where, as this species was a temporary 'visitor' seemingly tracing transgressive strata (Stouge et al. 2019) and is ambiguous to identify (see Mellgren 2011). ...
The Ordovician Period has emerged as a highly dynamic time in Earth history. Comprehensive work on chrono-, chemo- and biostratigraphy has resulted in an overall well-constrained systemic framework, but several local successions around the globe still await detailed analysis in many respects. Herein we perform a high-resolution analysis of abiotic and biotic signals in the Lynna River section, a key locality in northwestern Russia. As this section has been pivotal in documenting the temporal evolution of the Great Ordovician Biodiversification Event on Baltica, the macroscopic and microscopic characteristics of the local succession reveal important paleoenvironmental information that ties into the global development during the Middle Ordovician. The results add particularly to the understanding of the characteristics and large-scale sedimentary ‘behavior’ of the Baltoscandian paleobasin. Microfacies vary consistently with the macroscopic appearance of the rocks, with intervals characterized by competent limestone being associated with coarser carbonate textures and intervals dominated by marly beds associated with finer textures. Along with carbonate textures, fossil grain assemblages vary in a rhythmic (~cyclic) manner. The local rocks are commonly partly dolomitized, with the proportion of dolomitization increasing up-section. Regional comparisons suggest that the changes in overall macro- and microfacies were strongly related to variations in sea level. New high-resolution conodont biostratigraphic data largely confirm previous regional correlations based on lithostratigraphy and trilobite faunas, and enable more robust correlations worldwide.
... The Darriwilian biostratigraphy of Scania is here entirely based on the graptolite faunas, providing the best and most detailed differentiation possible. Conodont biozonations are less completely known from the region (e.g., Rasmussen 2001;Stouge & Nielsen 2003;Stouge 2005) and in certain intervals difficult to correlate, as are biostratigraphies based on the trilobite faunas from limestones in southern Sweden (cf. Nielsen 1995;Pärnaste et al. 2013). ...
... The Ordovician succession of the Fågelsång district, Scania (Fig. 10), has been investigated in some detail, largely on the basis of information from a number of drill cores (Hede 1951;Nilsson 1977;Stouge & Nielsen 2003;Bergström et al. 2018;, but also from outcrops (e.g. Moberg 1910;Hadding 1913;Ekström 1937). ...
... Bergström et al. (2018) stated that the Komstad Limestone in the Fågelsång-3 drill core agrees in all details with that of the Fågelsång-2 drill core and nearby outcrops, which have shown that the Komstad Limestone has a thickness of ca. 7.1 to 7.5 m (Stouge & Nielsen 2003). The Komstad Limestone in the Fågelsång region is known in great detail (Nielsen 1995;Stouge 2005) and will not be discussed herein. ...
The upper Middle to basal Upper Ordovician succession (Darriwilian to Sandbian) of the Fågelsång-3 drill core provides new important information on the graptolite biostratigraphy of Scania, southern Sweden. The Scanian succession is known largely from drill cores and a few scattered outcrops exposing only parts of the interval. The Darriwilian Almelund Shale Formation overlies the Komstad Limestone Formation and has a thickness of more than 42 m in the Fågelsång-3 drill core. A seemingly complete succession through the Holmograptus lentus, Nicholsonograptus fasciculatus, Pterograptus elegans, Pseudamplexograptus distichus and Jiangxigraptus vagus biozones can be recognized. Some intervals are poorly documented by their respective graptolite faunas or show extensive post-depositional tectonic deformation. The Nemagraptus gracilis Biozone of earliest Sandbian age cannot be positively identified, even though fragments of Nemagraptus have been discovered in the uppermost part of the Almelund Shale below the Fågelsång Phosphorite Bed.
... However, the interpretation of some of the species of this genus differs in detail among various authors (e.g., Dzik, 1976Dzik, , 1994Löfgren, 1978;Stouge and Bagnoli, 1990;Rasmussen, 2001). Several, but not all, of the Baltoniodus species are used as zonal nominate species in the biozonal system for the Baltoscandian platform (Bergström, 1971;Lindström, 1971a;Löfgren, 1978Löfgren, , 1995bLöfgren, , 2000Löfgren, , 2003Löfgren, , 2004Stouge, 1989;Stouge and Bagnoli, 1990;Dzik, 1991Dzik, , 1994Bagnoli and Stouge, 1997;Rasmussen, 2001;Viira et al., 2001;Stouge and Nielsen, 2003;Tolmacheva et al., 2001;Bergström and Löfgren, 2009;Fig. 3). ...
... The genus Lenodus appeared on Baltica in the Lenodus antivariabilis Zone (base of Darriwilian; cf. Stouge and Nielsen, 2003) and ranged to the top of the Lenodus pseudoplanus Zone (lower Darriwilian) (Fig. 3). The last member of the lineage, i.e. the informally named Lenodus sp. ...
... The first representative of the genus Lenodus (L. antivariabilis) immigrated to Baltica in earliest Darriwilian (Stouge and Nielsen, 2003). The taxon arrived during a period of low faunal diversity and was also represented by low numbers. ...
The stratigraphic distributions, taxonomy, diversity, evolutionary lineages and events of late Cambrian to Middle Ordovician euconodonts of Baltica are briefly reviewed and re-evaluated. The euconodonts of the late Furongian (Stage 10, late Cambrian) to Middle Ordovician successions of Baltica record innovation, immigration and two invasions of short duration and one major extinction. The innovation event with an origin on Baltica is the rise of the Proconodontus serratus lineage in the late Furongian (Stage 10). The immigration events comprise the Cordylodus immigration to Baltoscandia in latest Cambrian and this phylogenetic lineage persisted to mid Tremadocian (Early Ordovician) and vanished at the global mid-Tremadocian extinction event. The late Floian – basal Dapingian transition is a significant event on Baltica. It is characterized by the immigration of the important genera Baltoniodus and Microzarkodina and when first arrived these taxa stayed for a long period on the Baltica palaeocontinent forming evolutionary lineages. The basal Darriwilian immigration event by the genus Lenodus and coeval prominent sea-level lowstand were caused by a short global icehouse stage related to the expansion of the polar ice sheets. The extinction event caused the disappearance of the characteristic Cordylodus fauna. Most events are related to change of the palaeoclimate due to the movement of the Baltica palaecontinent and associated eustatic sea level changes. However, the cause of the global early Tremadocian extinction event is not yet completely clear and remains unsolved. Perhaps abrupt and significant palaeoceanographic changes on global scale i.e. plate tectonic movements causing sudden change of ocean currents and climate from warm to cold were the cause for this significant extinction in the Early Ordovician.
... In terms of the conodont succession, this interval represents the Lenodus antivariabilis Biozone (Figs. 2, 3). This is in general agreement with the conditions in the Fågelsång succession in southern Sweden where this conodont biozone is present in the interval of the U. austrodentatus Biozone (e.g., Stouge and Nielsen, 2003). However, in the latter succession, the base of the latter graptolite biozone is somewhat older than the base of the conodont L. antivariabilis Biozone. ...
A revised conodont biozonal scheme for the Ordovician of South China is presented herein based on extensive studies following the pioneer work by the late Professor An and his co-workers in the 1980s. This new classification of 33 biozones and subbiozones includes the conodont succession of the Yangtze Platform (29 biozones and subbiozones), the Jiangnan Slope (17 biozones), and a unique succession in the Qinling Orogen (four Katian biozones). The proposed biozone scheme provides more accurate correlations of the Ordovician strata in South China. As the best known and most detailed Ordovician conodont biozone succession in eastern Gondwana and peri-Gondwana, it will serve as a standard reference for correlation not only in this region but also for comparisons with the well-established biozone successions in Baltoscandia and North America. Furthermore, this new scheme has the potential to improve the precision in reconstruction of the conodont biofacies architecture in space and time. It will also assist in advancing our understanding of the timing and magnitude of biodiversification, oceanographic, and geological events at both the local and global scale.
... However, it is uncertain if the Tøyen Shale Formation was originally completely developed in the region, Komstad Limestone Formation is not too well known. Stouge & Nielsen (2003) pieced together the Komstad Limestone interval in the Fågelsång area from a number of drill cores and exposures but were unable to provide a definitive thickness of the unit. Gaps in the successions are difficult to recognize in the field due to the often extensive weathering, but may be more easily seen in drill cores. ...
The Ordovician Tøyen Shale Formation of the recently retrieved Fågelsång-3 drill core provides some important information on the graptolite biostratigraphy of the unit and its completeness in the region. The drill core reached downwards into the Kiaerograptus supremus Biozone of late Tremadocian age. Above a major fault zone, faunas with a number of specimens referred to Pseudophyllograptus densus are indicative of a late Dapingian age. Rare specimens of Azygograptus sp. also help constrain the age. The presence of Arienigraptus zhejiangensis indicates that the base of the Darriwilian Komstad Limestone Formation is of Levisograptus austrodentatus Biozone age. Specimens of Tetragraptus cor and Levisograptus sinicus in a shale bed within the lower part of the Komstad Limestone Formation can be referred to the upper subzone of the L. austrodentatus Biozone, the Levisograptus sinicus Subzone. This fauna represents the youngest graptolite fauna beneath the massive Komstad Limestone Formation. The Tøyen Shale Formation can be shown to be highly incomplete in Scania, possibly due to post-depositional tectonic deformation and faulting.
