Unicellular organic-walled microfossils from the Cambrian-Ordovician transition in Estonia (ca. 490-480 million years ago) exhibit rare characters reflecting their function as reproductive algal cysts. The studied assemblages record the evolutionary history of phytoplankton in the early Paleozoic Era: novel morphologies appearing through the Cambrian and subsequently diversifying in the Ordovician. Well preserved specimens were extracted following a standard palynological method and studied by light transmitted microscopy. The galeate plexus acritarchs Caldariola, Priscogalea and Stelliferidium have revealed exceptionally preserved morphological elements and a rare structure among both fossil and extant protists – an opening with operculum (lid) in reproductive cysts, in addition to lavish vesicle ornamentation and sculpture. Analogous morphology is observed in the living dasycladalean alga Acetabularia (Chlorophyta), which possesses an intrinsic lid-forming apparatus used during organism’s reproductive stage. Based on the observations on the fossil material and studies on the Acetabularia lid-formation, we propose a model of operculum formation in the galeate plexus microorganisms. Due to strong morphological and ecological similarities between galeate fossils and dasycladalean cysts, and the antiquity of this algal order, galeates may be positioned within green algae, more specifically Dasycladales. Unique morphology of the operculum-bearing microbiota would have required a high degree of intracellular complexity for its development, suggesting that advanced intracellular machinery was present already in the early Paleozoic phytoplankton. Additionally, minute prasinophyte microfossils Reticella corrugata are reported for the first time in the Upper Cambrian strata.
The Hornkullen mineralisation is situated in the westernmost part of the Bergslagen ore province, south-central Sweden. Here, polymetallic sulphides and oxides are hosted by an inlier of Svecofennian, c. 1.9Ga skarn-bearing metavolcanic units, enclosed in the c. 1.8Ga Filipstad granite belonging to the Transscandinavian Igneous Belt. The Ag- and Au-bearing mineralisation is dominated by veins and impregnations of magnetite, pyrrhotite, galena, chalcopyrite and arsenopyrite with subordinate pyrite, sphalerite, ilmenite, lollingite, Pb-Fe-Ag-Cu-Sb sulphosalts and rare gudmundite, pentlandite and molybdenite. Overall, a detailed textural and mineralogical study of the ore assemblages suggests significant deformation and remobilisation at high temperature, which is corroborated by sulphide geothermobarometry. The arsenopyrite geothermometer yields an average temperature of c. 525 degrees C, which is likely to be the result of metamorphic re-equilibration. Sphalerite geobarometry gives peak pressures of c. 300-400MPa, albeit with caveats. The combined observations suggest that the present mineralogical and textural nature of the ore assemblages at Hornkullen is primarily related to remobilisation during Svecokarelian regional metamorphism of a pre-existing, most likely syn-volcanic mineralisation. This scenario is likely to be applicable to many other Svecofennian metasupracrustal-hosted deposits in the Bergslagen ore province.
The late Llandovery graptolite fauna of the Retiolites Shales on Kinnekulle Mountain in the province of Västergötland has long been known but never illustrated or studied in detail. New collections of graptolites from an interval at the very top of the exposed succession confirm previous reports of cyrtograptids, which make the shales on Kinnekulle the youngest preserved Palaeozoic rocks in the area. The co-occurrence of Oktavites spiralis and Cyrtograptus lapworthi constrains the strata to the lower lapworthi Biozone of the upper Telychian. The associated graptolite fauna comprises numerous monograptids and Retiolites angustidens as well as Cyrtograptus kinnekullensis n. sp., characterised by its open coiling and the presence of a second-order cladium on the second thecal cladium. This early occurrence of a cyrtograptid species with a second-order cladium on Baltica matches evolutionary patterns observed in Laurentia, suggesting that the ability to grow cladia of both first and higher order evolved approximately, synchronously and at the very beginning of cyrtograptid evolution.
A new ore province, the Gold Line, southwest of the Skellefte District, northern Sweden, is currently under exploration. The largest known deposit in the Gold Line is the hypozonal Fäboliden orogenic gold deposit. The mineralization is hosted by arsenopyrite-bearing quartz veins, within a steep shear zone in amphibolite facies metagreywacke host rocks. Gold occur in fractures and as intergrowths in arsenopyrite-löllingite, and as free grains in the silicate matrix of the host rock. The hydrothermal mineral assemblage in the proximal alteration zone is diopside, calcic amphibole, biotite, and minor andalusite and tourmaline. Primary fluid inclusions in the Fäboliden quartz veins show a CO2-CH4 or a H2S (±CH4) composition (the latter recognized for the first time in a Swedish ore deposit). The primary fluid inclusions are associated with arsenopyrite-löllingite (+gold) and the CO2-CH4 fluid was also involved in precipitation of graphite. A prevalence of carbonic over aqueous fluid inclusions is characteristic for a number of hypozonal high-temperature orogenic gold deposits. The Fäboliden deposit, thus, shows fluid compositions similar to other hypozonal orogenic gold deposits. The proposed main mechanism for precipitation of gold from the fluids, is a mixing between H2S-rich and H2O?-CO2±CH4 fluids. Fluid inclusion data indicate arsenopyrite-löllingite and graphite deposition at a pressure condition of about 4 kbar. Graphite thermometry indicates maximum temperatures of 520-560°C for the hydrothermal alteration at Fäboliden, suggesting that at least the late stages of the mineralizing event took place shortly after peak-metamorphism in the area, i.e. at c. 1.80 Ga.
An assemblage dominated by acrotretid brachiopods (Prototreta millsi Brock and Percival, 2006) is described from the Nelson Limestone of the Transantarctic Mountains, Antarctica. The formation also includes paterinids (Micromitra sp. cf. M. nerranubawu Kruse, 1990 and Dictyonina australis Roberts, 1990), lingulids (Oepikites haimantensis Reed, 1910)and acrothelids (Acrothele sp. cf. A. vertex Reed, 1910). The macrofauna also contains orthids (Diraphora dyunyin Kruse, 1990). The associated fauna include sponge spicules present in vast abundance. Other recognisable small shelly fossils (including chancelloriids and hyolithelminths) make up a small section of the fauna. Trilobites (including Nelsonia schesis Palmer and Gatehouse, 1972 and Solenopleura pruina Palmer and Gatehouse, 1972) belong to taxa previously described from the Nelson Limestone and support the Drumianage proposed for the formation. Palaeobiogeographic analysis indicates that the brachiopod fauna corroborates previously described strong links with Australasia and also suggests a strong link to Indian material, corroborating previous evidence for an East Gondwanan faunal province in the Middle Cambrian.
Oscillatory-zoned euhedral single zircons from the upper Sandbian (Upper Ordovician) Kinnekulle K-bentonite exposed in a hillock at Paaskula in Estonia and at the type locality on Mt Kinnekulle in Sweden were dated in a grain-by-grain manner by laser ablation-inductively coupled plasma mass spectrometer. The U-Pb (weighed mean) ages of the 25 grains from Mt Kinnekulle and 24 grains from Paaskula are 453.4 +/- 6.6 and 454.9 +/- 4.9Ma, respectively. This study provides the first ca. 454Ma (late Sandbian) age for the Ordovician K-bentonite in northern Estonia and confirmed its correlation with the type Kinnekulle bed across the Baltic Sea.
Remains of 17(th) century cabinets of curiosity collections are held at the Museum of Evolution, Uppsala University, Sweden. Some of the oldest date back to the 1650s, and were included in the collection of Archiater, i.e. physician to the Crown, von Bromell (1679-1731). He is also known for publishing the first series of papers in Sweden to exclusively deal with palaeontology. Throughout his life he acquired specimens by collecting, buying or receiving in exchange to add to those he inherited from his father Olaus Bromelius, a famous botanist and physician. Information on the labels gives a glimpse of his network of friends, colleagues and fellow collectors, such as Kilian Stobaeus, Lars Roberg, Emanuel Swedenborg, Elias Brenner and Johan Dobelius. When Bromell died, his vast collections of books, coins, furniture, conchs, stuffed animals, minerals and fossils were sold off. The minerals and fossils were split up and owned by various persons during the following century. Parts owned by A. Lagerberg between the years 1746 and 1776 were bought in 1796 by Johan Afzelius and donated to Uppsala University at his death. Fossils and minerals earlier described by Bromell were in the care of The Royal Society of Science in Uppsala at least by 1791. Through the Institute of Geology, fossils accumulated over the centuries at Uppsala University eventually came together under the same roof in 1932, under professor Carl Wiman's care at the then newly erected Palaeontology museum building. Today, about 300 fossils from the Bromell collection are preserved at the museum.
The hyolith assemblage from the early Cambrian of Bornholm, Denmark, shows a higher diversity than contemporary assemblages in Baltoscandia. The most common species in the Green Shales (Laesa Formation, Norretorp Member, Cambrian Stage 3), is Hyolithes [=Hyolithus] (Orthotheca) johnstrupi Holm, 1893. A specimen of this species shows a well-preserved and almost complete digestive tract, folded into an approximately 22mm long chevron-like structure comprised of at least 20 arcuate loops on the ventral side and a flattened, gently sinuous to straight anal tube on the dorsal side. The thin, phosphatic outer shell layer of the conch is crushed under the digestive tract due to compaction while the digestive tract is preserved in three dimensions and appears undisturbed. The shape of the digestive tract is similar to that of the middle Cambrian Guduguwan hardmani (Etheridge) from Australia and the lower Cambrian specimens from Russia described by Mekova & Sysoev. The Danish specimen is probably an adult, lending support to the idea that the orthothecid digestive tract becomes more complex during ontogeny. Hyolithus (Orthotheca) johnstrupi is revised and here referred to Circotheca Sysoev, 1958.
The Orvar Hill formation in Tiveden, south-central Sweden, constitutes a unique low-strain window of well preserved Svecofennian mafic volcanic rocks on the southwestern border of the Svecokarelian orogen. The area can be considered as the southwestern border of the Bergslagen region of the Svecokarelian orogen. The Orvar Hill formation consists of coherent pillowed and non-pillowed basalts alternating with mafic volcaniclastic racks in the lower part of the Lindberga supracrustal succession. Only minor felsic volcanic rocks occur in the upper part. Quartz-bearing metagreywackes comprise the top part of the Lindberga supracrustal succession. Geochemistry of lavas and volcaniclastic rocks suggests that the Orvar Hill mafic volcanic rocks were emplaced in a volcanic-are setting. This demonstrates that the Tiveden supracrustal units probably formed in response to volcanism related to subduction. The Tiveden area may thus represent a 1.89 Ga primitive, sediment-starved volcanic are at the margin of the continental volcanic are of the Bergslagen district. The relationship between Tiveden and Bergslagen at the time of formation is not clear and Tiveden may represent a remnant of an are that accreted to a continent at c. 1.88-1.86 Ga.
Crinoids and brachiopods are described from the Silurian Uzyan Formation of the Zilair Zone in the southern Urals. The occurrence of the graptolites Coronograptus praedeubeli suggests a late Homerian (Wenlock) age for the strata. A new disparid crinoid, Cicerocrinus gracilis Donovan sp. nov., is the oldest known member of this genus. It has a long, flexible and homeomorphic column, and a tall bryozoan palaeontology terminology (IBr2) (second primibrachial) axillary. All species of Cicerocrinus described previously have been limited to the Ludlow of the British Isles, Sweden and Estonia, and the Pridoli of Estonia. The poorly preserved brachiopod fauna is represented by small atrypid (Atrypa? sp.) and dalmanellid brachiopods (Levenea? sp.). The reported assemblage generally inhabited deep-water environments.
A long history of geological research on the island of Gotland, Sweden, has resulted in a detailed biostratigraphy based on conodonts for the Gotland sedimentary succession, but the relation between the Hamra and Sundre formations, the youngest strata on southern Gotland, has remained poorly resolved. These formations have also remained relatively poorly described in terms of vertebrates compared to other parts of the succession. A survey of museum collections and newly sampled material reveal that the taxonomical compositions and richness of vertebrate faunas remain similar compared to the underlying Burgsvik Sandstone and Oolite members. However, the relative abundance of the respective groups changes: Paralogania ludlowiensis and rare osteostracan remains of Tahulaspis sp. only occur in samples from the lower Hamra Formation, while Thelodus sculptilis becomes more common in samples from Sundre Formation. Conodont and isotope data give support to previous suggestions that the Hamra and Sundre formations may be largely isochronous, and it is possible that the observed differences in vertebrate faunas reflect changes in depositional setting. This interval on Gotland has been suggested to represent a hiatus in the East Baltic sections, where younger strata show an increased importance of acanthodians in the vertebrate faunas. Gotland could therefore give insights into the early stages of this diversification of gnathostomes during late Silurian times. However, this has to be done in combination with data from other areas, as well as with a review and revision of the scale-based taxonomy of Silurian acanthodians from the Baltic Basin.
A Middle Cambrian (Series 3, Stage 5) echinoderm assemblage is described from the uppermost part of the Henson Gletscher Formation based on disarticulated material. This represents the first detailed echinoderm report from the Cambrian of North Greenland and one of the most diverse for that time. Recovered ossicles include a morphotype continuum between various biserial (brachiolar) and uniserial ("brachial") plates from pelmatozoan feeding appendages along with thecal insertion plates, pelmatozoan holomeric and the oldest known polymeric stem elements and holdfasts. Ambulacral flooring plates from two different edrioasteroids are also described. This assemblage illustrates a high plasticity and disparity in early echinoderm stem and feeding appendages, thereby placing stress on the usual definitions of blastozoans and crinozoans, generally considered as two pelmatozoan subphyla. Along with previous studies, it also raises the question as to how early echinoderms responded to the Agronomic Revolution (Substrate Revolution). Echinoderm remains first appear during Cambrian Series 2, Stage 3, well after the Substrate Revolution had affected the first few centimetres of substrate used by this low-level tiering animals to stabilize themselves. Contrary to previous ideas, it is suggested that echinoderms evolved quickly and in a nonlinear way in response to the abrupt establishment of a mosaic of substrate types during the early Cambrian. Finally, this study highlights the primary importance of disarticulated elements in the elucidation of the early evolution, diversity and disparity of the earliest echinoderms. Such elements are much more common and always appear earlier in the geological record than the complete articulated specimens on which echinoderm studies generally focus despite the taphonomic biases which often characterize their preservation.
The Dannemora supracrustal inlier is located in the north-eastern part of the Bergslagen regionin south-central Sweden and hosts the second largest iron ore deposit in the region. The metasupracrustalsuccession of the inlier consists of c. 1.9 Ga Palaeoproterozoic rocks that are mainly sub-alkaline, rhyoliticto dacitic, pyroclastic deposits, reworked pyroclastic deposits and metalimestone. It is c. 700–800-m thickand termed the Dannemora Formation. The formation is divided into lower and upper members and theformer is in turn subdivided into subunits 1 and 2. The great thickness of individual pyroclastic depositsindicates deposition within a caldera. The rocks show characteristics of a pyroclastic origin by containingabundant pumice, cuspate and Y-shaped former glass shards, and fragmented crystals of quartz andsubordinate feldspars. Scattered spherulites and lack of welding-compacted fiamme suggest that the lowermember was slightly welded, where as the upper member contains sericite-replaced glass shards withpreserved primary shapes indicating no welding. Undisturbed layers of ash-siltstone with normal gradingand fluid–escape structures are attributed to subaqueous deposition below storm wave base in the easternpart of the inlier, where as erosion channels and cross-bedding in some of the volcaniclastic deposits implydeposition and reworking above wave base in the central part of the inlier. Epidote spots, previouslyinterpreted as altered limestone fragments and an indicator for subaquatic deposition, are here reinterpretedas the result of selective alteration related to the intrusion of mafic dykes and to Ca release duringdolomitisation of limestone.
The Dannemora supracrustal inlier is located in the north-eastern part of the Bergslagen region in south-central Sweden and hosts the second largest iron ore deposit in the region. The metasupracrustal succession of the inlier consists of c. 1.9 Ga Palaeoproterozoic rocks that are mainly sub-alkaline, rhyolitic to dacitic, pyroclastic deposits, reworked pyroclastic deposits and metalimestone. It is c. 700–800-m thick and termed the Dannemora Formation. The formation is divided into lower and upper members and the former is in turn subdivided into subunits 1 and 2. The great thickness of individual pyroclastic deposits indicates deposition within a caldera. The rocks show characteristics of a pyroclastic origin by containing abundant pumice, cuspate and Y-shaped former glass shards, and fragmented crystals of quartz and subordinate feldspars. Scattered spherulites and lack of welding-compacted fiamme suggest that the lower member was slightly welded, where as the upper member contains sericite-replaced glass shards with preserved primary shapes indicating no welding. Undisturbed layers of ash-siltstone with normal grading and fluid–escape structures are attributed to subaqueous deposition below storm wave base in the eastern part of the inlier, where as erosion channels and cross-bedding in some of the volcaniclastic deposits imply deposition and reworking above wave base in the central part of the inlier. Epidote spots, previously interpreted as altered limestone fragments and an indicator for subaquatic deposition, are here reinterpreted as the result of selective alteration related to the intrusion of mafic dykes and to Ca release during dolomitisation of limestone.
Three cases of repaired injuries and malformation in specimens of the helcionelloid mollusc Helcionella antiqua (Ki & UAELIG;r, 1917) from the lower Cambrian (Cambrian Series 2, Stage 4) Gislov Formation of southern Sweden document some of the oldest known durophagous attacks on Palaeozoic molluscs. Two of the injuries are developed as clefts, of which one had a severe effect on the continued growth of the shell. The third example is a large embayment removing large portions of the supra-apical part of the shell. A similar repaired injury is known in the slightly older mollusc Marocella mira Geyer, 1986. from Antarctica and Australia. The morphology of the injuries and the hydrodynamically quiet depositional setting suggests that the shell damage was caused by failed predatory attacks. The location of the repaired injuries suggests that the attacks may have targeted the head region of the molluscs, thus supporting an endogastrically coiled orientation of the shell in Helcionella. Only three repaired injuries in 252 Helcionella specimens were found, giving a shell repair frequency of 1.2%. All three examples occur in the larger size classes. The size-frequency distribution (N = 182) is strongly right skewed, which could suggest high input of juvenile specimens into the assemblage. The assemblage is interpreted as a time averaged and mixed death assemblage, albeit with good correspondence with the living shelly assemblage, due to a relatively thin, homogenous unit that may suggest within-habitat time averaging.
Integration of new isotopic data and earlier biostratigraphic information from eight sections through the terminal Ordovician (Pirgu and Porkuni stages) of the Siljan district, Sweden, allows a more precise correlation of sections in terms of biostratigraphy and carbon isotope dating. Four levels with positive delta C-13 excursions are identified (from bottom) - the Moe, an unnamed excursion, Paroveja and Hirnantian Carbon Isotope Excursion (HICE). The delta C-13 values through the Boda Limestone are 1-2 parts per thousand higher than usual in Baltica, only the values for the HICE remains within what is expected. Background values increase from 1.5 parts per thousand in the bottom of the core of the Boda Limestone up to 3 parts per thousand in the top of it. The HICE is identified in five of eight sections and the main peak falls according to inferred correlation within the Metabolograptus persculptus Biozone, at or close to the Hindella beds in the Upper Boda Member. The late Katian (Pirgu) age of Holorhynchus in the Siljan district is clear and its co-occurrence with the chitinozoan Belonechitina gamachiana in Estonia supports a Katian age for this zone. The base of the Ozarkodina hassi Biozone may occur within units B-C of the Upper Boda Member and in the upper part of the Loka Formation and most likely is correlated with the M. persculptus Biozone. The Hirnantia-Dalmanitina faunas reported from the lowermost part of the Loka Formation and units B-D of the Upper Boda Member seem to range through all the Hirnantian, but detailed morphological studies allow to distinguish an older (=extraordinarius) and a younger (=persculptus) fauna.
The near planispiral euomphaloid gastropod Lesueurilla prima (Barrande in Perner) is a typical part of the cold water Mediterranean fauna in the Lower and Middle Ordovician. It is a signature species in strata of this age in the Prague Basin in the Czech Republic, Montagne Noire in France, and Central Morocco. The species is reported for the first time from the Darriwilian of Iran where it occurs in the upper part of the Shirgesht Formation of the Derenjal Mountains north of Tabas in east Central Iran. It occurs with a small species of the bellerophontoid gastropod Sinuites sp., as well as the calymenid trilobite Neseuretinus birmanicus (Reed) and the pliomerid trilobite Ovalocephalus kanlingensis (Zhang). The biogeographic distribution of Lesueurilla suggests that the genus had its origin in cold water, high-latitude peri-Gondwana areas during the Lower Ordovician, spreading to other peri-Gondwana areas and low-latitude areas of North China, Tarim, and finally Baltica, Laurentia and Australia in the late Middle and Upper Ordovician.
A mass aggregation of 148 paradoxidid trilobites and associated specimens of the agnostoid Pentagnostus praecurrens is preserved on a surface of a split orsten lens from the Middle Cambrian Series 3 Acadoparadoxides pinus-P. praecurrens Zone in Jamtland, Sweden. Most specimens are complete or nearly complete, lying parallel to the sediment surface and seem unaffected by currents or sorting. The association is interpreted as a moult ensemble. Paradoxidid specimens are represented by two taxa, identified as paradoxidid sp. 1 (n=28 specimens) and Eccaparadoxides sp. 2 (n=45 specimens). The species are preserved both dorsum up and dorsum down, in about equal number, which may reflect a natural tendency to moult in either posture. They probably moulted by opening the cephalic sutures along the wide rostrum. The dorsal sutures are invariably open and the librigenae are very often displaced, commonly backwards in relation to the cranidium, but not symmetrically in relation to the axial shield. The glabella of the paradoxidids is often crushed, so that sometimes the underlying hypostome is outlined. Very few examples show the joint between the cranidium and the trunk being broken. Facies interpretation suggests deposition below storm wave base. Rapid burial, possibly by blanketing from hypopycnal flows followed by an extended period of slow sediment input (Type 1 facies of Brett et al. 2012) may explain the unusual preservation. The animals may have lived in an ex-aerobic environment, but evidence to support this is at the moment insubstantial.
The Lower Ordovician Bjørkasholmen Formation at Flagabro, Scania, southern Sweden, consists of a 0.8m thick succession of carbonates with three siliciclastic mudstones, 5, 1 and 100mm thick, intercalated in the central part of the unit. Carbonate and siliciclastic mudstone beds show both normal and inverse grading. The carbonates are mud-rich and subdivided into a mudstone, a wackestone and a packstone facies. Grain types in the carbonates are mostly shells and shell fragments of brachiopods and trilobites. The carbonate rocks are strongly bioturbated seen as in roundish burrows filled with mud and a clear cement; additionally, bioturbation is reflected in the random orientation of shells. The siliciclastic mudstones are subdivided into two facies; one contains large amounts of shells and is in part grain-supported, the other is matrix-dominated and laminated to massive. The succession reflects sedimentation on a low-inclined shelf equivalent to a mid-ramp to basinal setting. Most mud- and wackestones (facies 3 and 4) represent fair-weather sedimentation, and the intercalated wacke- and packstones (facies 4 and 5) represent concentration of shell debris during high-energy storm. The siliciclastic mudstones in the central part of the succession reflect deposition in a basinal setting. The entire BjOrkasholmen Formation at Flagabro is equivalent to a lowstand of third (?) order without a well-developed internal cyclicity and is in that respect similar to the Bjørkasholmen Formation of oland, but different from the age-equivalent Norwegian sections.
Three new orthide species: Orthidium lavensis, Orthidium gambolovensis and Ranorthis rotunda, and one new protorthide species: Skenidioides minutus, are described from the Early-Middle Ordovician (Billingen-Volkhov stages) of Estonia and north-western Russia. This is the first record of Orthidium from Baltica, whereas Skenidioides was known previously only from the Keila and Oandu stages in Estonia.
Although plesiosaurs and mosasaurs co-existed for about 35 million years at the end of the Cretaceous, the fossil record documenting interactions between these two groups of marine reptiles is meagre. The discovery of deeply incised scars on a limb bone of an immature polycotylid plesiosaur from the latest early Campanian (in the European two-fold division of the Campanian Stage) of the Kristianstad Basin, southern Sweden, is thus significant because it represents a rare example of predation or scavenging on an immature polycotylid plesiosaur by a large mosasaur.
Two assemblages from the Ordovician rocks of the Arctic region contain exclusively trepostome bryozoans. The first assemblage from the Yunoyaga Formation (Middle Ordovician) of Maly Oleniy Island, Novaya Zemlya, contains Monticulipora mammulata d’Orbigny, 1850 and Nicholsonella vaupeliformis Modzalevskaya, 1955. Both species possess thick-branched ramose colonies characteristic for rather high energy environments. The second assemblage comes from two localities of the Stroinaya Formation (Upper Ordovician) of the October Revolution Island containing the single species Amplexopora angusta Astrova, 1965. The monospecific bryozoan fauna of branched, rarely encrusting growth forms and sedimentological characteristics of embedding rocks (floatstone) suggest low energy conditions in deeper environments, apparently accompanied by high salinity conditions.
A fauna of 12 species of paragastropods, tergomyans and gastropods is described from the Upper Ordovician (Kukruse Stage to Idavare substage) Dalby Limestone of Tvären, Lockne, and Fjäcka (Sweden), presenting a higher diversity than previously recognized. The presence of Mimospira, Laeogyra, Sarkanella epelys n. sp. indicates a strong faunal connection with Bohemia, Czech Republic. Sarkanella is reported from outside Bohemia for the first time. Bucania erratica n. sp. represents one of the earliest records of the genus in Baltoscandia. A single case of shell repair from failed predation is recorded in this species. Synonyms for Eccyliopterus princeps Remelé and E. regularis Remelé are proposed. The significance of Laeogyra, Eccyliopterus, and Deaechospira for regional correlation within the Upper Ordovician of Baltoscandia is confirmed.
Trilobites of the late Tremadocian Apatokephalus serratus trilobite Zone, the Ceratopyge fauna, are abundant and widely distributed across Baltoscandia. During the Tremadocian they occur in the initial stable carbonate deposits on the platform (the Bjørkåsholmen Formation in the west; Djupvik and Köpingsklint formations in the east). Two sections at Ottenby and Degerhamn, southern Öland, Sweden, were investigated for trilobite abundance distribution. At Degerhamn and Ottenby the fauna is restricted to 70 and 78 cm respectively. In the Degerhamn quarry the fauna appears in the Djupvik Formation. At both localities the abundance distributions are similar, with an initial dominance of Ceratopyge acicularis and Shumardia pusilla, followed by a marked shift to a dominance of nileid species (Symphysurus angustatus, Varvia longicauda, Nileus limbatus). Comparisons with the Oslo Region showed a remarkably similar distribution pattern, and three biofacies are recognized. In the Oslo Region the Ceratopyge-Shumardia biofacies, the Bienvillia biofacies, and the nileid biofacies are developed. Only two of these are present on Öland, where the short lived drowning represented by the Bienvillia biofacies in the Oslo Region is not recorded. Within the nileid biofacies, Nileus and Varvia are more frequent on Öland than in the Oslo Region. The three biofacies may be applied to other areas of the Baltoscandian platform where this facies is present and potentially be used to discriminate depth gradients.
A new bivalved arthropod Erjiecaris minusculo gen. et sp. nov. is described from the Lower Cambrian Chengjiang Lagerstatte, Yunnan, southwest China. It possesses mosaic features, such as the reduced shield that is dorsoventrally flattened, dorsally positioned eyes, ring-shaped somites and broad furcal rami. These provide an important link for assessing the evolutionary morphological gap between two distinctive Cambrian arthropod groups, crustaceanomorph and trilobite-like taxa. Thus, the new finding reported here in turn improves the understanding of the body plan of early arthropods and provides fresh insight into the evolution of the carapace/head shield and visual system.
Underthrusting of Laurentia by the continental margin of Baltica during Caledonian orogeny resulted in the lateral emplacement of Iapetus Ocean-related terranes of the Upper Allochthon at least 500 km onto Baltica. The underlying Lower and Middle allochthons of the Baltoscandian margin mostly comprise Cryogenian, Ediacaran and Cambro-Silurian sedimentary successions; basement to these formations are present only as minor, isolated fragments, except at the base of the Middle Allochthon and within the underlying windows. The upper parts of the Middle Allochthon are notable for the presence of early Ediacaran dyke-swarms and other components of the Baltoscandian continent-ocean transition zone (COT). New data are presented here on the c. 610 Ma age of the COT-related dolerites in the Kalak Nappe Complex in Northern Norway and also on detrital zircons in the underlying Laksefjord and Gaissa nappes. The former confirms that the Baltoscandian COT has a similar age along the length of the orogen; the latter shows that the detrital zircon signatures in the Lower and Middle allochthons are comparable throughout the orogen. These sedimentary rocks have dominating populations of Mesoproterozoic to latest Palaeoproterozoic zircons similar to those from southern parts of the orogen, where Sveconorwegian complexes comprise the basement to the Caledonides. Thus, they help define the probable character and age of the crystalline basement that existed along this outer margin of Baltica during the Neoproterozoic, continental lower crust that was partly subducted during Ordovician continent-arc collision and subsequently lost beneath Laurentia during the 50 million years of Scandian collisional orogeny.
The COSC project is focused on the mid Paleozoic Caledonide Orogen in Scandinavia in order to better understand orogenic processes, both in the past and in today's active mountain belts. It relates to two of ICDP's main themes - the fundamental physics of plate tectonics and heat, mass and fluid transfer through Earth's crust, and on improving interpretation of geophysical data used to determine the structure and properties of the Earth's crust. Lateral transport of Caledonian allochthons over distances of several hundreds of kilometers in the Scandes, by a combination of thrusting and ductile extrusion, is comparable to that recognized in the Himalayas. The Caledonides in Scandinavia provide special opportunities for understanding Himalayan-type orogeny and the Himalayan Orogen itself, thanks to the deep level of erosion and the paucity of superimposed post-Paleozoic deformation. The surface geology in combination with the seismic, magnetotelluric, magnetic and gravity data provide control of the geometry of the Caledonian structure, both of the allochthon and the underlying parautochthon-autochthon, and define the locations for drilling. The latter will investigate both the high-grade, ductile Caledonian nappes and the underlying allochthons and basement, with two c. 2.5km deep boreholes, located near re and Jarpen in western Jamtland. The two boreholes will also provide unique information about other important aspects of the Scandinavian bedrock, including the heat flow and potential for geothermal energy, mineralization in the Seve nappes and alum shales, the uplift history of the Scandes, the Holocene paleoclimatological changes and the deep biosphere.
The problem of the existence of the asthenosphere for old Precambrian cratons is still discussed. In order to study the seismic lithosphere-asthenosphere boundary (LAB) beneath the Baltic Shield, we used records of nine local earthquakes with magnitudes ranging from 2.7 to 5.9. To model the LAB, original data were corrected for topography and Moho depth using a reference model with a 46-km-thick crust. For two northern events at Spitsbergen and Novaya Zemlya, we observe a low-velocity layer, 60-70-km-thick asthenosphere, and the LAB beneath Barents Sea was found at depth of c. 200km. Sections for other events show continuous first arrivals of P-waves with no evidence for "shadow zone" in the whole range of registration, which could either be interpreted as the absence of the asthenosphere beneath the central part of the Baltic Shield, or that the LAB in this area occurs deeper (>200km). The relatively thin low-velocity layer found beneath southern Sweden, 15km below the Moho, could be interpreted as small-scale lithospheric heterogeneities, rather than asthenosphere. Differentiation of the lower lithosphere velocities beneath the Baltic Shield could be interpreted as regional heterogeneity or as anisotropy of the Baltic Shield lithosphere, with high velocities approximately in the east-west direction, and slow velocities approximately in the south-north direction.
The oldest known specimens of the enigmatic mollusc Jinonicella kolebabai PokornATIN SMALL LETTER Y WITH ACUTE, 1978 are redescribed from Middle Ordovician strata of Ukraine and Belarus. The phosphatic internal moulds preserve imprints of growth lines, hitherto only documented in Silurian specimens. The persistent distribution of Jinonicella in the Baltoscandian basin of the Russian Platform suggests that this was the centre of origin of this taxon. During the Silurian, Jinonicella inhabited Siberia and Laurentia, and the smaller European terranes of Bohemia and the Carnic Alps. In the Devonian, Jinonicella is reported from Laurentia, Bohemia and the Rhenish Massif.
Unique preservation of the oldest colour pattern (approximate to 490Ma) of a molluscan shell and the first record of colour pattern in monoplacophorans are reported from a well that penetrated Early Ordovician strata in the Timan-Pechora Basin of Russia. The unusual preservation reflects low subsidence temperatures and minimal tectonic deformation. A colour pattern in the form of radial stripes coincides with the pattern of multiple muscle attachments to the shell, which obviously influenced the mantle margin responsible for the shell formation and pigment deposition. We assume that this type of colour pattern is one of the most ancient to have appeared in molluscan evolution.
The small problematic mollusc Jinonicella kolebabai Pokorný, 1978 is described from the lower Silurian Laketown Dolostone at Barn Hills in Utah, USA. The associated conodonts suggest a late Telychian age for the assemblage, which makes this the oldest occurrence of this species. Previous Silurian records of Jinonicellawere known from the Sheinwoodian to Ludfordian of Bohemia, the Czech Republic, Gotland, Sweden and the Carnic Alps of Austria.
Jinonicella kolebabai Pokorný, 1978, a small problematic “mollusc” of unknown origin is described from the early Silurian (early to mid Llandovery) of east Siberia. This is the first record of Jinonicella from Siberia. Previous Silurian records of Jinonicella were from the late Llandovery (Telychian) of North America and the Wenlock to Ludlow of Europe (Bohemia, Gotland and the Carnic Alps of Austria). Jinonicella shows a wide range of geographic and stratigraphic distribution. It was reported from three palaeocontinents and several smaller terranes. It also demonstrates adaptation to different environments from shallow to deep-water settings, and spans several climatic zones from equatorial to temperate belts. The wide distribution and adaptation to a broad range of environments allow Jinonicella to subsist for about 100 my, i.e., from the Middle Ordovician to the Late Devonian surviving through two major extinction events.
Compositional zoning in iron oxyhydroxides precipitated from mine drainage-contaminated groundwater was studied by electron microprobe (EMP) analysis. The observed zoning is characterized by variations in Al, Fe, S, and Si concentrations, with mean precipitate concentrations of ca. 56.0 wt.% Fe, 1.1 wt.% Al, 2.0 wt.% Si, and 0.5 wt.% S. The analyses indicate an inverse relationship between AI-Si concentrations and Fe-S concentrations in the Fe oxyhydroxides. The results and groundwater data from the field site suggest that the origin of compositional zoning in the Fe oxyhydroxides is controlled by both surface complexation reactions involving Al3+ and H4SiO4, which affect goethite formation kinetics, and the Al/Fe and Si/Fe molar ratios in solution.
A new rare Upper Ordovician mound dwelling palaeoloricate chiton is described asCrassaplax collicolagen. et sp. nov. from three large isolated intermediate valves from the Katian carbonate mud mounds of the Boda Limestone in the Siljan district of central Sweden. Together with the previously knownSpicuchelodes? sp., also from the Boda Limestone, these are the only known Late Ordovician mound dwellers so far among the palaeoloricates, adding to Ordovician environments with reported chiton remains.Crassaplax collicolais distinguished from other Ordovician palaeoloricate chitons by their thick and large valves that can be 2 cm in length, and especially the clear differentiation between the lateral and central valve areas.
The Early Triassic (late Induan to early Olenekian) Lingula borealis Bittner, from the Russkii Island on the Pacific cost of south-eastern Russia is revised, based on re-examination of the type material. Although this species, like most described Triassic lingulids, has remained very poorly understood due to the lack of information on important characters, such as musculature and mantle canals, it has been commonly recorded in subsequent studies and included in attempts at understanding the patterns of extinction and recovery at around the Permian-Triassic boundary. Linguliform brachiopods are some of the notable survivors of this significant mass extinction event. Lingula borealis has previously been referred to Lingularia and provisionally synonymised with Lingularia similis Biernat & Emig. Here, it is shown that it differs from Lingularia similis mainly in characters of mantle canals, musculature and most importantly in details of the pedicle nerve impression. In Lingularia borealis, the impression of the pedicle nerve is symmetrical and goes almost straight between the individual ventral umbonal muscle scars, whereas in Lingularia similis it is asymmetrically positioned towards the smaller left component of the ventral umbonal muscle scar. Shell structures and details of preserved ontogenies have also proven to be important for the discrimination of lingulid taxa, but cannot be provided from the types of Lingularia borealis.
The type species of the poorly understood Ordovician acrotretoid brachiopod Conotreta, C. rusti Walcott, 1889, is redescribed, based on a re-study of the syntypes and new topotypes from the Ordovician (late Mohawkian; late Caradoc) Denmark Limestone at Tr
The first Cambrian phosphatic brachiopods (Subphylum Linguliformea, Class Lingulata) are described from the San Juan Precordillera of western Argentina, including Neotreta tumida Sobolev, Quadrisonia minor Rowell & Henderson, Prototreta cf. mimica Bell, C
The type area of the coarse-grained, K-feldspar megacrystbearing Revsund granites is located in Jämtland County. These granites cover an area of c. 6.000 km2 in the western part of northern Sweden, and their emplacement ages have been established to c. 1.80 Ga from granites located outside and at the margin of the type area. Some of the rocks originally classified as Revsund granite in the southeastern part of Jämtland have later been interpreted to belong to the early Svecofennian suite. U-Pb SIMS analyses of zircon from one such rock and two Revsund granites from the type area, yield indistinguishable ages: 1854±8, 1858±9, and 1859±11 Ma, respectively. These ages are considerably older than the established age, suggesting that there either are two magmatic events forming the Revsund granites or that further K-feldspar megacryst-bearing granites in the type area must be re-classified. The ages achieved partly overlap with the ages of the 1.84–1.85 Ga, Kfeldspar megacryst-bearing Ljusdal granitoids located to the southeast. However, these rocks are metamorphosed and penetratively deformed, and have thus experienced a different tectonometamorphic evolution than have the Revsund granites in Jämtland, which are mainly isotropic outside shear zones.
The Hyttsjö granites occur in the extensively mineralised Långban-Nordmark area in the westernmost part of the Bergslagen ore province. They have been classified as late Svecokarelian granites due to their homogeneous and generally isotropic appearance in addition to a WR Rb/Sr age. Moreover, they have been considered as possible candidates for supplying essential metals to epigenetic mineralisation in this classic ore district. Two Hyttsjö granites yield U-Pb zircon data ages of 1791±2 and 1793±3 Ma, respectively, which overlap with emplacement ages of the adjacent 1.80-1.78 Ga Filipstad suite belonging to the Transscandinavian Igneous Belt (TIB). Mafic rocks occur quite abundantly associated with the Filipstad-type granite (sensu lato) and various types of mafic enclaves as well as hybrid rocks are present, suggesting a co-magmatic origin. Such mafic intrusives are also exposed in the vicinity of most known Hyttsjö-type plutons. Not least our observations that the former exhibit back-veining by granitic melts suggest intimate causal and temporal relationships between granite formation and mafic TIB rocks. The Hyttsjö granites were probably produced through partial melting related to the intrusion of hot, mafic magmas in and along the border between the TIB and the Svecofennian supracrustal and subvolcanic rocks. Thus, all available observations and data suggest that the Hyttsjö granites are intimately related to and most probable a product of TIB magmatism. Also, they do not lend any support for the hypothesis that the formation of the Hyttsjö granites represent a temporally separate intrusive episode. The Hyttsjö granites are therefore unlikely to be discernibly responsible for specific mineralisation in this area.
The Svecofennian is a large hot orogen composed of different accreted crustal units. The boundaries between these units are often characterised by major, steeply dipping shear zones with post-accretionary signatures. However, some of these shear zones have recorded an earlier and long-lived activity related to the accretionary episode, so have moderately eastward dipping shear zones identified in the eastern part of the Ljusdal Domain in the central part of the orogen. These shear zones, repeated at multiple lithostratigraphical levels, are associated with west verging asymmetric F2-folds indicating thrusting with imbricate slices in thickness comparable to those in the Caledonides. In the Ljusdal Domain these structures have been recognised in rock of significantly different metamorphic grade indicating thick-skin thrusting on the crustal scale possibly accompanied by channel flow. Information from deep drilling through these stacked units would shed light on the tectonostratigraphy and consequently the accretionary to post-accretionary evolution of hot orogens. In addition, information about groundwater circulation, geothermal energy potential and reservoir quality of tectonically layered rocks for e.g. CO2 sequestration experiments in crystalline rocks would be gained.
An anastomosing pattern of NW-SE to NNW-SSE trending, ductile shear zones have affected the Precambrian bedrock in central Jämtland. Spatially these structures are related to two major shear zone systems, the Storsjön-Edsbyn Deformation Zone (SEDZ) and the Hassela Shear Zone (HSZ). Several of the local zones occur between Lake Näkten and Lake Locknesjön and coincide with linear magnetic anomalies. The dextral kinematics recorded are emphasised by clockwise rotation of early Svecofennian rocks, that partly are arranged in a large-scale C/S pattern. Three different, ductile shear zones yield U-Pb titanite ages of 1801±1, 1799±7, and 1794±3 Ma, interpreted to date the deformation. Pale titanite overgrowths, colourless titanite, and apatite yield younger U-Pb ages (c. 1.75 Ga) which argue for a tectonic reactivation of the zones, or a later thermal and/or hydrothermal event, as indicated by intrusions of cross-cutting pegmatites and felsic dykes. A hydrothermal activity during the Caledonian orogeny is recorded in one of the deformation zones. This is shown by an altered fabric containing titanites with pale outer parts which are severely discordant in a U-Pb concordia diagram with a Palaeozoic lower intercept. Sm-Nd analyses on re-precipitated zircon grains also deviate considerably from a Palaeoproterozoic trend given by other minerals in the assemblage.
The Ordovician age Lockne and Devonian Siljan craters are two of the largest impact structures in northern Europe. Both formed in targets with a thick, low-strength upper layer. This target configuration is known to generate concentric crater structures with an outer, shallow crater in the low-strength layer, surrounding a central, deeper crater in the more resistant substrate. The concentric craters of Lockne and Siljan are excellent models for studies of similar concentric craters on Earth and elsewhere in the Solar system. Several structural issues remain, and drilling through the craters within the Swedish Deep Drilling Program intends to address the following: the extent of the craters with respect to the time of impact; the effects of cratering on the basement; and the role of basement structure for the crater formation. A problem for the Lockne crater is the relation to the Caledonian orogeny and the lateral extension of the ejecta blanket - the rim is interrupted by a radial depression that has been interpreted both as primary and secondary, tectonically induced. A second feature to study is the deeper and older (1.82-1.80 Ga) NNW-SSE shear zones that cut the basement. In the Siljan area the development of mega block associations comprising the infilling of the graben is disputed. The blocks may either be formed by sagging of peripheral parts of the fault blocks or alternatively by major radial movement involving kilometre long transport.
Sclerites of machaeridians (Annelida) and polyplacophorans (Mollusca) from the UpperOrdovician (Katian–Hirnantian) Boda Limestone of the Siljan district, central Sweden are described forthe first time. Four taxa of machaeridians were found, but with one exception they are either known froma single isolated sclerite or only one type of sclerite. The largest taxon is represented by an inner modifiedsclerite of Plumulites sp. A from Osmundsberget Quarry. The complete scleritome is estimated to havereached a length of 12–15 cm. A more diverse material allows the description of Plumulites eueides sp.nov. from Kallholn Quarry. Within smaller cavities in Solberga Quarry minute sclerites of two taxa werefound; Lepidocoleus sp., and Turrilepas sp. The latter record represents the third known Ordovicianoccurrence and the youngest from that period. Association with minute blind trilobites andconcentrations of tiny articulated ostracodes suggest that these small cavities represented cryptichabitats. Two polyplacophoran sclerites are also described: one intermediate sclerite of Chelodes sp. Afrom Jutja¨rn Quarry, with only the outer surface exposed, and one intermediate sclerite of Spicuchelodes?sp. from Kallholn Quarry, with only the inner surface exposed. These represent rare examples ofOrdovician chitons recorded from outside Laurentian terranes.
Pleurotomaria? kunda pik, 1926 was correctly referred to the genus Aldanella Vostokova, 1962 more than 30 years ago, although its affinities are still debated. It has been described by several authors as a gastropod on account of its helically coiled shell but it is here referred to the Class Helcionelloida, a group of Cambrian-Ordovician untorted molluscs which are usually bilaterally symmetrical. A sub-sutural, spiral muscle scar trace on the internal mould is described, as is a possible attachment area on the umbilical shoulder. Impressions of a prismatic shell structure are present in the apical region. In the lower Cambrian (proposed Cambrian Series 1) Kestla Member of the Lontova Formation, Aldanella kunda occurs together with Anabarella Vostokova, 1962, another helcionelloid that is also characteristic of Cambrian Series 1 in Siberia. Scenella(?) discinoides Schmidt, 1888 from the slightly younger Tiskre Formation (Cambrian Series 2) was originally assigned to a genus widely interpreted as a mollusc, but this species has been re-interpreted recently as a possible stem group brachiopod.
A growing literature of deep but also surficial fossilized remains of lithobiological life, often associated with igneous rocks, necessitates the unfolding of a sub-discipline within paleobiology. Here, we introduce the term paleolithobiology as the new auxiliary sub-discipline under which fossilized lithobiology should be handled. We present key criteria that distinguish the paleolithobiological archive from the traditional one and discuss sample strategies as well as scientific perspectives. A majority of paleolithobiological material consists of deep biosphere fossils, and in order to highlight the relevance of these, we present new data on fungal fossils from the Lockne impact crater. Fungal fossils in the Lockne drill cores have been described previously but here we provide new insights into the presence of reproductive structures that indicate the fungi to be indigenous. We also show that these fungi frequently dissolve and penetrate secondary calcite, delineating the role lithobionts plays in geobiological cycles. We hope that the formalization of the sub-discipline paleolithobiology will not only highlight an overlooked area of paleobiology as well as simplify future studies of endo- and epilithic fossil material, but also improve our understanding of the history of the deep biosphere.
Ludfordian strata exposed in the Burgen outlier in eastern Gotland, Sweden record a time of initial faunal recovery after a global environmental perturbation manifested in the Ludfordian Carbon Isotope Excursion (LCIE). Vertebrate microfossils in the collection of the late Lennart Jeppsson, hosted at the Swedish Museum of Natural History, hold the key to reconstruct the dynamics of faunal immigration and diversification during the decline of the LCIE, but the stratigraphic relationships of the strata have been debated. Historically, they had been placed in the Burgsvik Formation, which included the Burgsvik Sandstone and the Burgsvik Oolite members. We revise the fauna in the Jeppsson collection and characterize key outcrops of Burgen and Kapellet. The former Burgsvik Oolite Member is here revised as the Burgen Oolite Formation. In the Burgen outlier, back-shoal facies of this formation are represented and their position in the Ozarkodina snajdri Biozone is supported. The shallow-marine position compared to the coeval strata in southern Gotland is reflected in the higher delta C-13(carb) values, reaching +9.2 parts per thousand. The back-shoal succession includes high-diversity metazoan reefs, which indicate a complete recovery of the carbonate producers as the LCIE declined. The impoverishment of conodonts associated with the LCIE in southern Gotland might be a product of facies preferences, as the diverse environments in the outlier yielded all 21 species known from the formation. Fish diversity also returned to normal levels as the LCIE declined, with a minimum of nine species. In line with previous reports, thelodont scales appear to dominate samples from the Burgen outlier.
The presence of cobalt (Co) in sulphide deposits or sulphide-bearing iron oxide deposits in and around the Palaeoproterozoic Bergslagen ore province, south central Sweden, led to focused mining and extraction of this metal, particularly during the nineteenth century. Today, Co is considered a critical metal in the EU and among the more sought-after raw materials, not least due to its use in batteries for the rapidly increasing production of electric vehicles. Here we report new observations and data on Co concentrations in variably mineralised and not necessarily statistically representative samples from a suite of mainly skarn-hosted, at least locally, sulphide-dominated mineralisations from Bergslagen. While several localities that exhibit substantial Co concentrations represent deposits previously known to carry this metal (generally in a field/district or specifically in a mine), the majority are from mines or prospects in which the presence of Co have been hitherto unknown. Several of them share the enrichment of, e.g., Co and Cu, but the overall picture is one of more complex interrelations between the variable metal endowments in the known occurrences of Co in this province. While representing a modest dataset, our new observations complement previously available information on the occurrence of Co in Bergslagen and highlights both the need for, and potential of, new and more detailed studies on the distribution, mineralogy and origin of Co as well as other critical or near-critical metals in this and other ore provinces in Sweden.