Pub Date : 2020-07-02DOI: 10.1080/11035897.2020.1781245
S. McLoughlin
ABSTRACT An assemblage of permineralized conifer and angiosperm woods collected from Paleogene marine strata on Seymour Island during the Swedish Antarctic expedition of 1901–1903 includes many specimens with internal damage caused by an array of xylophagous organisms. Short, broad, clavate borings referable to Gastrochaenolites clavatus are attributed to pholadid bivalves. Elongate borings with carbonate linings referable to Apectoichnus longissimus were produced by teredinid bivalves. Slender, cylindrical tunnels cross-cutting growth rings and backfilled in meniscoid fashion by frass composed of angular tracheid fragments were probably produced by a terrestrial beetle borer. They are most similar to tunnels generated by modern cerambycid and ptinid coleopterans. Less regular, spindle-shaped cavities and degraded zones flanking growth rings are similar to fungi-generated modern white pocket rot. Larger chambers in the heartwood referable to the ichnotaxon Asthenopodichnium lignorum were produced by an alternative mode of fungal degradation. The biological interactions evident in the fossil woods illustrate additional terrestrial trophic levels enhancing the known complexity of ecosystems on and around the Antarctic Peninsula shortly before the initial pulse of mid-Cenozoic glaciation in Antarctica that caused extirpation of the majority of plants and animals in that region.
{"title":"Marine and terrestrial invertebrate borings and fungal damage in Paleogene fossil woods from Seymour Island, Antarctica","authors":"S. McLoughlin","doi":"10.1080/11035897.2020.1781245","DOIUrl":"https://doi.org/10.1080/11035897.2020.1781245","url":null,"abstract":"ABSTRACT An assemblage of permineralized conifer and angiosperm woods collected from Paleogene marine strata on Seymour Island during the Swedish Antarctic expedition of 1901–1903 includes many specimens with internal damage caused by an array of xylophagous organisms. Short, broad, clavate borings referable to Gastrochaenolites clavatus are attributed to pholadid bivalves. Elongate borings with carbonate linings referable to Apectoichnus longissimus were produced by teredinid bivalves. Slender, cylindrical tunnels cross-cutting growth rings and backfilled in meniscoid fashion by frass composed of angular tracheid fragments were probably produced by a terrestrial beetle borer. They are most similar to tunnels generated by modern cerambycid and ptinid coleopterans. Less regular, spindle-shaped cavities and degraded zones flanking growth rings are similar to fungi-generated modern white pocket rot. Larger chambers in the heartwood referable to the ichnotaxon Asthenopodichnium lignorum were produced by an alternative mode of fungal degradation. The biological interactions evident in the fossil woods illustrate additional terrestrial trophic levels enhancing the known complexity of ecosystems on and around the Antarctic Peninsula shortly before the initial pulse of mid-Cenozoic glaciation in Antarctica that caused extirpation of the majority of plants and animals in that region.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1781245","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44287041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-07-02DOI: 10.1080/11035897.2020.1781246
A. Hall, Mikis van Boeckel
ABSTRACT The present marine Baltic Sea basin (BSB) occupies an eroded Proterozoic intra-cratonic basin on the Fennoscandian shield. Competing models propose a Neogene fluvial origin, with later modification by glacial erosion, or a much younger development, with overdeepening beneath the Fennoscandian Ice Sheet (FIS). We test these alternatives using a first order source to sink sediment budget for the catchment of the BSB. Best estimates derived from geomorphic and cosmogenic nuclide evidence suggest depths of erosion over the last 1 Ma of 20 m in basement and 40 m in sedimentary rocks that surround the BSB. As the BSB has been overdeepened below a regional base level provided by the shallow Darss Sill at the boundary with the Kattegat, erosion of the BSB may be interpreted as glacial in origin, without a fluvial component. The estimated total volume of source area erosion is 30,628 km3 of which 87% is derived from the present BSB. Sediment volumes in the sink area within the limits of maximum Pleistocene glaciation are estimated at a minimum of 37,629 km3, after correction for local erosion, porosity, and carbonate losses. Marine Isotope Stage 12 and younger sediments account for 87% of the total Pleistocene sediment volume in the sink in Poland. Although significant uncertainties remain, the sediment budget is consistent with erosion of the BSB entirely by the FIS, mainly when the ice sheet reached its maximum extent and thickness during the Middle and Late Pleistocene glaciations.
{"title":"Origin of the Baltic Sea basin by Pleistocene glacial erosion","authors":"A. Hall, Mikis van Boeckel","doi":"10.1080/11035897.2020.1781246","DOIUrl":"https://doi.org/10.1080/11035897.2020.1781246","url":null,"abstract":"ABSTRACT The present marine Baltic Sea basin (BSB) occupies an eroded Proterozoic intra-cratonic basin on the Fennoscandian shield. Competing models propose a Neogene fluvial origin, with later modification by glacial erosion, or a much younger development, with overdeepening beneath the Fennoscandian Ice Sheet (FIS). We test these alternatives using a first order source to sink sediment budget for the catchment of the BSB. Best estimates derived from geomorphic and cosmogenic nuclide evidence suggest depths of erosion over the last 1 Ma of 20 m in basement and 40 m in sedimentary rocks that surround the BSB. As the BSB has been overdeepened below a regional base level provided by the shallow Darss Sill at the boundary with the Kattegat, erosion of the BSB may be interpreted as glacial in origin, without a fluvial component. The estimated total volume of source area erosion is 30,628 km3 of which 87% is derived from the present BSB. Sediment volumes in the sink area within the limits of maximum Pleistocene glaciation are estimated at a minimum of 37,629 km3, after correction for local erosion, porosity, and carbonate losses. Marine Isotope Stage 12 and younger sediments account for 87% of the total Pleistocene sediment volume in the sink in Poland. Although significant uncertainties remain, the sediment budget is consistent with erosion of the BSB entirely by the FIS, mainly when the ice sheet reached its maximum extent and thickness during the Middle and Late Pleistocene glaciations.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1781246","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44711038","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-06-18DOI: 10.1080/11035897.2020.1753807
Mathis Warlo, C. Wanhainen, O. Martinsson, P. Karlsson
ABSTRACT The Liikavaara Östra Cu-(W-Au) deposit is situated close to the operating Aitik Cu-Au mine in northern Sweden. It is scheduled for production in 2023. Modern geological descriptions of the deposit are lacking though knowledge of geological and mineralogical details prior to operation is beneficial to avoid surprises. In this study, petrological, mineralogical and geochemical investigations of the wall rocks, host rock and mineralisation, and zircon U-Pb analysis of a footwall granodioritic intrusion were carried out. The mineralisation is hosted by quartz±tourmaline-calcite veins, calcite veins and aplite dykes that cross-cut biotite-amphibole schists and gneisses. The wall rocks to the ore are metavolcaniclastic rocks of basaltic to andesitic composition. A granodiorite intrusion occurs in the footwall. The mineralisation is mainly chalcopyrite, pyrrhotite and pyrite with some sphalerite, galena, scheelite, molybdenite and magnetite. It shows slight enrichments in Au, Ag and Bi. Gold and Ag occur as electrum and Ag also in hessite and an Ag-sulphide. The Bi mineralogy includes native Bi, Bi-tellurides and Bi-sulphides. These minerals are found as inclusions, along the borders of and in cracks in chalcopyrite, pyrite, pyrrhotite, sphalerite, molybdenite and quartz. The footwall granodiorite intrusion was dated at 1.87 Ga. It is suggested here to be the source for ore genesis based on its spatial relation to the mineralisation, as well as on high-salinity fluids and metal composition of the ore. The aplite dykes may have acted as pathways for the magmatic hydrothermal fluids that carried the metals from the intrusion to the host rock.
{"title":"Mineralogy and character of the Liikavaara Östra Cu-(W-Au) deposit, northern Sweden","authors":"Mathis Warlo, C. Wanhainen, O. Martinsson, P. Karlsson","doi":"10.1080/11035897.2020.1753807","DOIUrl":"https://doi.org/10.1080/11035897.2020.1753807","url":null,"abstract":"ABSTRACT The Liikavaara Östra Cu-(W-Au) deposit is situated close to the operating Aitik Cu-Au mine in northern Sweden. It is scheduled for production in 2023. Modern geological descriptions of the deposit are lacking though knowledge of geological and mineralogical details prior to operation is beneficial to avoid surprises. In this study, petrological, mineralogical and geochemical investigations of the wall rocks, host rock and mineralisation, and zircon U-Pb analysis of a footwall granodioritic intrusion were carried out. The mineralisation is hosted by quartz±tourmaline-calcite veins, calcite veins and aplite dykes that cross-cut biotite-amphibole schists and gneisses. The wall rocks to the ore are metavolcaniclastic rocks of basaltic to andesitic composition. A granodiorite intrusion occurs in the footwall. The mineralisation is mainly chalcopyrite, pyrrhotite and pyrite with some sphalerite, galena, scheelite, molybdenite and magnetite. It shows slight enrichments in Au, Ag and Bi. Gold and Ag occur as electrum and Ag also in hessite and an Ag-sulphide. The Bi mineralogy includes native Bi, Bi-tellurides and Bi-sulphides. These minerals are found as inclusions, along the borders of and in cracks in chalcopyrite, pyrite, pyrrhotite, sphalerite, molybdenite and quartz. The footwall granodiorite intrusion was dated at 1.87 Ga. It is suggested here to be the source for ore genesis based on its spatial relation to the mineralisation, as well as on high-salinity fluids and metal composition of the ore. The aplite dykes may have acted as pathways for the magmatic hydrothermal fluids that carried the metals from the intrusion to the host rock.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1753807","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46501832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-05-18DOI: 10.1080/11035897.2020.1739743
J. Maletz, P. Ahlberg, Frans Lundberg
ABSTRACT The graptolite biostratigraphy of the 116.11-m-long Röstånga-2 drill core from Scania, southern Sweden, includes the Darriwilian (Middle Ordovician) Holmograptus lentus, Nicholsonograptus fasciculatus, Pterograptus elegans, Pseudamplexograptus distichus and Jiangxigraptus vagus biozones, and the lower Sandbian (Upper Ordovician) Nemagraptus gracilis Biozone. The early Darriwilian Komstad Limestone was not reached. The succession includes numerous levels of brecciated rocks and slickensides, suggesting considerable tectonic deformation and possible gaps. The boundary between the Almelund Shale Formation (below) and the Sularp Shale Formation (above) has been identified at 19.55–19.70 m, where the Fågelsång Phosphorite Bed has been identified tentatively in the Jiangxigraptus vagus Biozone. The first specimens of Nemagraptus gracilis appear higher in the succession. The international correlation of the Darriwilian graptolite succession is discussed.
{"title":"Ordovician graptolite biostratigraphy of the Röstånga-2 drill core (Scania, southern Sweden)","authors":"J. Maletz, P. Ahlberg, Frans Lundberg","doi":"10.1080/11035897.2020.1739743","DOIUrl":"https://doi.org/10.1080/11035897.2020.1739743","url":null,"abstract":"ABSTRACT The graptolite biostratigraphy of the 116.11-m-long Röstånga-2 drill core from Scania, southern Sweden, includes the Darriwilian (Middle Ordovician) Holmograptus lentus, Nicholsonograptus fasciculatus, Pterograptus elegans, Pseudamplexograptus distichus and Jiangxigraptus vagus biozones, and the lower Sandbian (Upper Ordovician) Nemagraptus gracilis Biozone. The early Darriwilian Komstad Limestone was not reached. The succession includes numerous levels of brecciated rocks and slickensides, suggesting considerable tectonic deformation and possible gaps. The boundary between the Almelund Shale Formation (below) and the Sularp Shale Formation (above) has been identified at 19.55–19.70 m, where the Fågelsång Phosphorite Bed has been identified tentatively in the Jiangxigraptus vagus Biozone. The first specimens of Nemagraptus gracilis appear higher in the succession. The international correlation of the Darriwilian graptolite succession is discussed.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-05-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1739743","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49167176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/11035897.2020.1724668
M. Tuchkova, S. Shokalsky, O. Petrov, S. Sokolov, S. Sergeev, A. Moiseev
ABSTRACT Upper Triassic sandstones from Mendeleev Rise were analyzed and compared to turbiditic sandstones of the same age from Wrangel Island and Chukotka, Arctic Sea region. Medium-grained lithic arenites dominate all of these. The quartz content is higher in the sandstones from Mendeleev Rise than in those from Wrangel Island and Chukotka. Abundant quartz grains with microfractures and kaolinized feldspar are characteristic of the samples from Mendeleev Rise, whereas such features are lacking in the other areas. Quartz with microfractures is less abundant in Triassic turbidite sandstones of Chukotka and Wrangel and kaolinized feldspar is not present. Upper Triassic sandstones of Mendeleev Rise are characterized by a high Chemical Index of Alteration indicating intensive weathering in the source province. All sandstones have Th/Sc ratios ≤1. The chemical composition of sandstones suggests a quartzose sedimentary province for sandstones of Mendeleev Rise, an intermediate igneous province for Wrangel Island sandstones, and a mafic igneous provenance for Chukotka sandstones. Detrital zircon populations are similar in all Upper Triassic sandstones samples with a dominance of Paleozoic zircon. Facies studies of Triassic deposits in the Eastern Arctic of Russia indicate that sandstones from Mendeleev Rise were located near a continent and formed in a shallow or coastal-marine setting. Triassic deposits of Wrangel Island and Chukotka were deposited in a deeper marine environment.
{"title":"Triassic deposits of Chukotka, Wrangel Island and Mendeleev Rise, Arctic Sea: sedimentology and geodynamic implications","authors":"M. Tuchkova, S. Shokalsky, O. Petrov, S. Sokolov, S. Sergeev, A. Moiseev","doi":"10.1080/11035897.2020.1724668","DOIUrl":"https://doi.org/10.1080/11035897.2020.1724668","url":null,"abstract":"ABSTRACT Upper Triassic sandstones from Mendeleev Rise were analyzed and compared to turbiditic sandstones of the same age from Wrangel Island and Chukotka, Arctic Sea region. Medium-grained lithic arenites dominate all of these. The quartz content is higher in the sandstones from Mendeleev Rise than in those from Wrangel Island and Chukotka. Abundant quartz grains with microfractures and kaolinized feldspar are characteristic of the samples from Mendeleev Rise, whereas such features are lacking in the other areas. Quartz with microfractures is less abundant in Triassic turbidite sandstones of Chukotka and Wrangel and kaolinized feldspar is not present. Upper Triassic sandstones of Mendeleev Rise are characterized by a high Chemical Index of Alteration indicating intensive weathering in the source province. All sandstones have Th/Sc ratios ≤1. The chemical composition of sandstones suggests a quartzose sedimentary province for sandstones of Mendeleev Rise, an intermediate igneous province for Wrangel Island sandstones, and a mafic igneous provenance for Chukotka sandstones. Detrital zircon populations are similar in all Upper Triassic sandstones samples with a dominance of Paleozoic zircon. Facies studies of Triassic deposits in the Eastern Arctic of Russia indicate that sandstones from Mendeleev Rise were located near a continent and formed in a shallow or coastal-marine setting. Triassic deposits of Wrangel Island and Chukotka were deposited in a deeper marine environment.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1724668","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49429763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/11035897.2020.1739742
H. Mutvei
ABSTRACT The sub-class Nautiloidea is divided into two super-orders, Nautilosiphonata and Calciosiphonata, based on different structural types of the connecting rings. The late Cambrian order Plectronocerida has the calciosiphonate type of connecting ring similar to that in post-Cambrian orthocerids. It is structurally more complex than the nautilosiphonate connecting ring in late Cambrian ellesemerocerid-like nautiloids. The plectronocerid nautiloids, therefore, evolved from the ellesmerocerid-like nautiloids and not vice versa. As indicated by the complex siphuncular structure in plectronocerids, cephalopod evolution began earlier than previously estimated, probably in the early Cambrian. The siphuncle in cephalopods originated from a calcareous septum that became partially non-calcified and formed the connecting ring.
{"title":"Restudy of some plectronocerid nautiloids (Cephalopoda) from the late Cambrian of China; discussion on nautiloid evolution and origin of the siphuncle","authors":"H. Mutvei","doi":"10.1080/11035897.2020.1739742","DOIUrl":"https://doi.org/10.1080/11035897.2020.1739742","url":null,"abstract":"ABSTRACT The sub-class Nautiloidea is divided into two super-orders, Nautilosiphonata and Calciosiphonata, based on different structural types of the connecting rings. The late Cambrian order Plectronocerida has the calciosiphonate type of connecting ring similar to that in post-Cambrian orthocerids. It is structurally more complex than the nautilosiphonate connecting ring in late Cambrian ellesemerocerid-like nautiloids. The plectronocerid nautiloids, therefore, evolved from the ellesmerocerid-like nautiloids and not vice versa. As indicated by the complex siphuncular structure in plectronocerids, cephalopod evolution began earlier than previously estimated, probably in the early Cambrian. The siphuncle in cephalopods originated from a calcareous septum that became partially non-calcified and formed the connecting ring.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1739742","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42034657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/11035897.2020.1748898
P. Andreasson
ABSTRACT In the Swedish Caledonides, the continent-ocean boundary is represented by the basal thrust of the Iapetus-derived Köli Nappe Complex (KNC) which overlies the Seve Nappe Complex (SNC) derived from the outer rifted margin of Baltica and the continent-ocean transition (COT). Current maps and literature subdivide the Seve teconostratigraphy in northern Sweden (Sarek-Padjelanta region) into three mega-lenses, the lowest of which (Vaimok lens) is composed of quartz-feldspathic gneisses and subordinate marble, all hosting eclogites. It is overlain by the Sarek lens composed of a COT dyke complex and, along its western margin, a narrow belt of phyllites, schists, quartzite, marbles and greenschists. Overlying this belt is Tsäkkok lens of the same composition as the Vaimok lens. The situation with an intermediate-pressure and often excellently preserved sheeted-dyke complex intercalated between two lenses of complexly deformed high-pressure rocks invited to intricate models of accretion, including out-of-sequence stacking of slices of the continental margin during early Ordovician subduction. Based on a detailed study of a select area and examination of the evolution of previous concepts, this study reinterprets the narrow belt along the western margin of the Sarek Lens as typical of the lower KNC. The favoured explanation of the presence of intermediate-pressure Köli rocks below high-pressure Seve rocks is recumbent folding and/or mega-sheath folding of the Seve-Köli nappe sequence during Scandian (Siluro-Devonian) accretion, by analogy with the situation in places in the central Swedish Caledonides. Previous models of early out-of-sequence stacking during subduction of the continental margin need reconsideration.
{"title":"The continent-ocean (Seve-Köli) boundary in the Sarek-Padjelanta Mts. revisited: Swedish Caledonides","authors":"P. Andreasson","doi":"10.1080/11035897.2020.1748898","DOIUrl":"https://doi.org/10.1080/11035897.2020.1748898","url":null,"abstract":"ABSTRACT In the Swedish Caledonides, the continent-ocean boundary is represented by the basal thrust of the Iapetus-derived Köli Nappe Complex (KNC) which overlies the Seve Nappe Complex (SNC) derived from the outer rifted margin of Baltica and the continent-ocean transition (COT). Current maps and literature subdivide the Seve teconostratigraphy in northern Sweden (Sarek-Padjelanta region) into three mega-lenses, the lowest of which (Vaimok lens) is composed of quartz-feldspathic gneisses and subordinate marble, all hosting eclogites. It is overlain by the Sarek lens composed of a COT dyke complex and, along its western margin, a narrow belt of phyllites, schists, quartzite, marbles and greenschists. Overlying this belt is Tsäkkok lens of the same composition as the Vaimok lens. The situation with an intermediate-pressure and often excellently preserved sheeted-dyke complex intercalated between two lenses of complexly deformed high-pressure rocks invited to intricate models of accretion, including out-of-sequence stacking of slices of the continental margin during early Ordovician subduction. Based on a detailed study of a select area and examination of the evolution of previous concepts, this study reinterprets the narrow belt along the western margin of the Sarek Lens as typical of the lower KNC. The favoured explanation of the presence of intermediate-pressure Köli rocks below high-pressure Seve rocks is recumbent folding and/or mega-sheath folding of the Seve-Köli nappe sequence during Scandian (Siluro-Devonian) accretion, by analogy with the situation in places in the central Swedish Caledonides. Previous models of early out-of-sequence stacking during subduction of the continental margin need reconsideration.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1748898","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45688271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/11035897.2019.1686419
D. Loydell, N. Walasek
ABSTRACT Two new species of graptolite are described from the lower part of the Spirograptus turriculatus Biozone (lower Telychian) of Kallholn Quarry, Dalarna, Sweden. Pristiograptus paradoxus sp. nov. is ventrally curved and is more similar to uppermost Wenlock–Ludlow Bohemograptus species than to other Llandovery Pristiograptus species. Torquigraptus loveridgei sp. nov. is stratigraphically intermediate between the well-known species, T. planus and T. proteus.
{"title":"Two new species of graptolite from the Telychian (upper Llandovery, Silurian) of Kallholn, Dalarna, Sweden","authors":"D. Loydell, N. Walasek","doi":"10.1080/11035897.2019.1686419","DOIUrl":"https://doi.org/10.1080/11035897.2019.1686419","url":null,"abstract":"ABSTRACT Two new species of graptolite are described from the lower part of the Spirograptus turriculatus Biozone (lower Telychian) of Kallholn Quarry, Dalarna, Sweden. Pristiograptus paradoxus sp. nov. is ventrally curved and is more similar to uppermost Wenlock–Ludlow Bohemograptus species than to other Llandovery Pristiograptus species. Torquigraptus loveridgei sp. nov. is stratigraphically intermediate between the well-known species, T. planus and T. proteus.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2019.1686419","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48863011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/11035897.2020.1728374
J. S. Peel
ABSTRACT The distinctive, tall and slender cyrtoconic shell of the gastropod Pollicina cyathina Koken, 1897, originally established on a poorly preserved internal mould from the Middle Ordovician of the Dalarna region of central Sweden, is redescribed on the basis of additional material from several localities in the vicinity of Rättvik. Repaired injuries preserved in the fine comarginal growth lines of the archinacelloidean gastropod indicate failed durophagous predatory attacks. Unusual apical structures on an internal mould from Sjurberg probably result from closure of the earliest growth stages later in ontogeny.
{"title":"The Dala thumb: shell morphology and failed predation in Pollicina cyathina (Gastropoda) from the Ordovician of Dalarna, Sweden","authors":"J. S. Peel","doi":"10.1080/11035897.2020.1728374","DOIUrl":"https://doi.org/10.1080/11035897.2020.1728374","url":null,"abstract":"ABSTRACT The distinctive, tall and slender cyrtoconic shell of the gastropod Pollicina cyathina Koken, 1897, originally established on a poorly preserved internal mould from the Middle Ordovician of the Dalarna region of central Sweden, is redescribed on the basis of additional material from several localities in the vicinity of Rättvik. Repaired injuries preserved in the fine comarginal growth lines of the archinacelloidean gastropod indicate failed durophagous predatory attacks. Unusual apical structures on an internal mould from Sjurberg probably result from closure of the earliest growth stages later in ontogeny.","PeriodicalId":55094,"journal":{"name":"Gff","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/11035897.2020.1728374","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46158305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-04-02DOI: 10.1080/11035897.2020.1751270
N. Jansson, Weihua Liu
ABSTRACT We address controls on Co and Ni distribution, based on their solubility in hydrothermal fluids as functions of pH, ƒO2 and T, in two end-member types of sulphide deposits in Bergslagen, Sweden. Oxidized hydrothermal fluids, as have been suggested for the formation of the Zinkgruvan deposit, would efficiently transport Co and Ni in solution, even at 150 °C. Formation of Co and Ni sulphides and sulphosalts supersedes or overlaps the precipitation of other sulphides along a reduction or H2S-mixing path. This is consistent with the presence of Co and Ni sulphides and sulphosalts in vent-proximal Cu-Zn mineralization at Zinkgruvan. Reduced, acidic and hot (≥250 °C) hydrothermal fluids that have been invoked for the formation of deposits like Falun and Stollberg could also transport Co and Ni in solution. However, their solubility is strongly dependent on high T and low pH. Cooling and neutralization are here proposed as likely key triggers for the deposition of Co and Ni, yet, unlike in the Zinkgruvan scenario, saturation will occur within the pyrite stability field, whereby these metals may be sequestered as stoichiometric lattice substitutions in pyrite and other sulphides rather than forming minerals of their own. We conclude that at any T or realistic pH, hydrothermal systems involving oxidized brines have a greater ability to traverse and leach large rock volumes of Co and Ni. Consequently, areas hosting deposits that formed from such brines have a significant exploration potential for these metals, even in areas where Co-enriched source rocks are lacking or subordinate.
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