Abstract. Various Eocene hyperthermal events have been recorded from lignite sections of western India in the past decade. To infer the paleoenvironment, during a warm paleotropical climate of India, we have assessed multiple microfossil groups like pollen/spores, dinoflagellates and foraminifera from Early Eocene lignite mine sections from the Cambay (Surkha) and Barmer (Giral) basins and Middle Eocene sections from the Kutch Basin (Matanomadh and Panandhro mines) of western India. The Surkha and Giral sections exhibit a dominance of rainforest elements (Arengapollenites achinatus, Longapertites retipilatus), thermophilic mangrove palm Nypa and (sub)tropical dinoflagellate cyst Apectodinium, Cordosphaeridium and Kenleyia. This palynomorph assemblage is indicative of a marginal marine setting within a hot and humid climate. During the Middle Eocene, the diversity of dinocyst assemblage increased and a decrease in percentage of mangrove elements was observed in the Matanomadh and Panandhro mine sections of the Kutch Basin as compared to the Early Eocene sections of western India. Bloom of triserial planktic (Jenkinsina columbiana) and rectilinear benthic (Brizalina sp., Trifarina advena rajasthanensis) foraminifera indicates eutrophic conditions of deposition during the Late Lutetian–Early Bartonian in the lignite sections of the Kutch Basin which later changed to oligotrophic, open marine conditions towards the Bartonian (planktic E12 zone). This change to oligotrophic conditions coincides with a drastic increase in diversity of planktic foraminifera in the top portion of lignite mines of the Kutch Basin which may be correlated with the Kirthar–Wilson Bluff transgression event in the Bartonian observed across basins in India, Pakistan and Australia potentially linked to sea level rise around the Middle Eocene Climatic Optimum.
{"title":"Record of Early to Middle Eocene paleoenvironmental changes from lignite mines, western India","authors":"S. Khanolkar, J. Sharma","doi":"10.5194/JM-38-1-2019","DOIUrl":"https://doi.org/10.5194/JM-38-1-2019","url":null,"abstract":"Abstract. Various Eocene hyperthermal events have been recorded from lignite sections\u0000of western India in the past decade. To infer the paleoenvironment, during a\u0000warm paleotropical climate of India, we have assessed multiple microfossil\u0000groups like pollen/spores, dinoflagellates and foraminifera from Early Eocene\u0000lignite mine sections from the Cambay (Surkha) and Barmer (Giral) basins and\u0000Middle Eocene sections from the Kutch Basin (Matanomadh and Panandhro mines) of\u0000western India. The Surkha and Giral sections exhibit a dominance of\u0000rainforest elements (Arengapollenites achinatus, Longapertites retipilatus), thermophilic mangrove palm Nypa and (sub)tropical\u0000dinoflagellate cyst Apectodinium, Cordosphaeridium and\u0000Kenleyia. This palynomorph assemblage is indicative of a marginal\u0000marine setting within a hot and humid climate. During the Middle Eocene, the\u0000diversity of dinocyst assemblage increased and a decrease in percentage of\u0000mangrove elements was observed in the Matanomadh and Panandhro mine sections of\u0000the Kutch Basin as compared to the Early Eocene sections of western India.\u0000Bloom of triserial planktic (Jenkinsina columbiana) and rectilinear\u0000benthic (Brizalina sp., Trifarina advena rajasthanensis) foraminifera indicates eutrophic conditions of deposition during the Late\u0000Lutetian–Early Bartonian in the lignite sections of the Kutch Basin which later changed\u0000to oligotrophic, open marine conditions towards the Bartonian (planktic E12\u0000zone). This change to oligotrophic conditions coincides with a drastic\u0000increase in diversity of planktic foraminifera in the top portion of lignite\u0000mines of the Kutch Basin which may be correlated with the Kirthar–Wilson Bluff\u0000transgression event in the Bartonian observed across basins in India, Pakistan and\u0000Australia potentially linked to sea level rise around the Middle\u0000Eocene Climatic Optimum.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42525606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nadia Al-Sabouni, Isabel S. Fenton, R. Telford, M. Kučera
Abstract. Applications of planktonic foraminifera in Quaternary palaeoceanographic and palaeobiological studies require consistency in species identification. Yet the degree of taxonomic consistency among the practitioners and the effects of any potential deviations on community structure metrics have never been quantitatively assessed. Here we present the results of an experiment in taxonomic consistency involving 21 researchers representing a range of experience and taxonomic schools from around the world. Participants were asked to identify the same two sets of 300 specimens from a modern subtropical North Atlantic sample, one sieved at >125 µm and one at > 150 µm. The identification was carried out either on actual specimens (slide test) or their digital images (digital test). The specimens were fixed so the identifications could be directly compared. In all tests, only between one-quarter and one-eighth of the specimens achieved absolute agreement. Therefore, the identifications across the participants were used to determine a consensus ID for each specimen. Since no strict consensus (>50 % agreement) could be achieved for 20–30 % of the specimens, we used a “soft consensus” based on the most common identification. The average percentage agreement relative to the consensus of the slide test was 77 % in the >150 µm and 69 % in the >125 µm test. These values were 7 % lower for the digital analyses. We find that taxonomic consistency is enhanced when researchers have been trained within a taxonomic school and when they regularly perform community analyses. There is an almost negligible effect of taxonomic inconsistency on sea surface temperature estimates based on transfer function conversion of the census counts, indicating the temperature signal in foraminiferal assemblages is correctly represented even if only two-thirds of the assemblage is consistently identified. The same does not apply to measures of diversity and community structure within the assemblage, and here we advise caution in using compound datasets for such studies. The decrease in the level of consistency when specimens are identified from digital images is significant and species-specific, with implications for the development of training sets for automated identification systems.
{"title":"Reproducibility of species recognition in modern planktonic foraminifera and its implications for analyses of community structure","authors":"Nadia Al-Sabouni, Isabel S. Fenton, R. Telford, M. Kučera","doi":"10.5194/JM-37-519-2018","DOIUrl":"https://doi.org/10.5194/JM-37-519-2018","url":null,"abstract":"Abstract. Applications of planktonic foraminifera in Quaternary palaeoceanographic and\u0000palaeobiological studies require consistency in species identification. Yet\u0000the degree of taxonomic consistency among the practitioners and the effects\u0000of any potential deviations on community structure metrics have never been\u0000quantitatively assessed. Here we present the results of an experiment in\u0000taxonomic consistency involving 21 researchers representing a range of\u0000experience and taxonomic schools from around the world. Participants were\u0000asked to identify the same two sets of 300 specimens from a modern\u0000subtropical North Atlantic sample, one sieved at >125 µm\u0000and one at > 150 µm. The identification was carried out\u0000either on actual specimens (slide test) or their digital images\u0000(digital test). The specimens were fixed so the identifications could be\u0000directly compared. In all tests, only between one-quarter and one-eighth of\u0000the specimens achieved absolute agreement. Therefore, the identifications\u0000across the participants were used to determine a consensus ID for each\u0000specimen. Since no strict consensus (>50 % agreement) could be\u0000achieved for 20–30 % of the specimens, we used a “soft consensus” based\u0000on the most common identification. The average percentage agreement relative\u0000to the consensus of the slide test was 77 % in the >150 µm\u0000and 69 % in the >125 µm test. These values\u0000were 7 % lower for the digital analyses. We find that taxonomic\u0000consistency is enhanced when researchers have been trained within a taxonomic\u0000school and when they regularly perform community analyses. There is an almost\u0000negligible effect of taxonomic inconsistency on sea surface temperature\u0000estimates based on transfer function conversion of the census counts,\u0000indicating the temperature signal in foraminiferal assemblages is correctly\u0000represented even if only two-thirds of the assemblage is consistently\u0000identified. The same does not apply to measures of diversity and community\u0000structure within the assemblage, and here we advise caution in using compound\u0000datasets for such studies. The decrease in the level of consistency when\u0000specimens are identified from digital images is significant and\u0000species-specific, with implications for the development of training sets for\u0000automated identification systems.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43205808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Benthic foraminiferal populations were studied in a shallow bay of San Salvador Island, the Bahamas. Surface sediments and marine macrophytes were collected from 14 sample sites along a 500 m transect at Grahams Harbour to investigate the foraminiferal assemblage in each microhabitat and to test the link between dead foraminiferal test accumulation patterns and living epiphytic and sedimentary foraminiferal assemblages, macrophyte distribution, and environmental gradients. The analyses include grain size measurements, macrophyte biomass quantification, and qualitative and quantitative studies of benthic foraminifera. The foraminifera found attached to macrophytes differed between macrophyte habitats. However, a correlation between these living communities and the dead assemblages in the sediments at the same sites could not be observed. Principal component analysis (PCA) and redundancy analysis (RDA) suggest that the presence of the macroalgae Halimeda explains 16 % of the residual faunal variation in the dead foraminiferal assemblage after the effects of sorting according to fall speed are partialled out. The RDA also reflects a positive correlation between foraminifera larger than 1.0 mm in diameter and the 0.25–0.5 mm sediment grain size, indicating sedimentological processes as the main factor controlling the sedimentary epiphytic foraminiferal assemblages. These sedimentary processes overprint most effects of ecological features or macrophyte-specific association.
{"title":"Benthic foraminiferal assemblages and test accumulation in coastal microhabitats on San Salvador, Bahamas","authors":"A. Fischel, M. Seidenkrantz, Bent Vad Odgaard","doi":"10.5194/JM-37-499-2018","DOIUrl":"https://doi.org/10.5194/JM-37-499-2018","url":null,"abstract":"Abstract. Benthic foraminiferal populations were studied in a shallow bay of San Salvador\u0000Island, the Bahamas. Surface sediments and marine macrophytes were collected\u0000from 14 sample sites along a 500 m transect at Grahams Harbour to\u0000investigate the foraminiferal assemblage in each microhabitat and to test the\u0000link between dead foraminiferal test accumulation patterns and living\u0000epiphytic and sedimentary foraminiferal assemblages, macrophyte distribution,\u0000and environmental gradients. The analyses include grain size measurements,\u0000macrophyte biomass quantification, and qualitative and quantitative\u0000studies of benthic foraminifera. The foraminifera found attached to\u0000macrophytes differed between macrophyte habitats. However, a correlation\u0000between these living communities and the dead assemblages in the sediments at\u0000the same sites could not be observed. Principal component analysis (PCA) and\u0000redundancy analysis (RDA) suggest that the presence of the macroalgae\u0000Halimeda explains 16 % of the residual faunal variation in the dead\u0000foraminiferal assemblage after the effects of sorting according to fall speed\u0000are\u0000partialled out. The RDA also reflects a positive correlation between\u0000foraminifera larger than 1.0 mm in diameter and the 0.25–0.5 mm sediment\u0000grain size, indicating sedimentological processes as the main factor\u0000controlling the sedimentary epiphytic foraminiferal assemblages. These\u0000sedimentary processes overprint most effects of ecological features or\u0000macrophyte-specific association.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42178074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Integrated Ocean Drilling Program (IODP) Expedition 318 recovered a ∼ 170 m long Holocene organic-rich sedimentary sequence at Site U1357. Located within the narrow but deep Adélie Basin close to the Antarctic margin, the site accumulated sediments at exceptionally high sedimentation rates, which resulted in extraordinary preservation of the organic sedimentary component. Here, we present an overview of 74 different mainly marine microfossil taxa and/or types found within the organic component of the sediment, which include the remains of unicellular and higher organisms from three eukaryotic kingdoms (Chromista, Plantae, and Animalia). These remains include phytoplanktonic (phototrophic dinoflagellates and prasinophytes) and very diverse zooplanktonic (heterotrophic dinoflagellates, tintinnids, copepods) organisms. We illustrate each marine microfossil taxon or type identified by providing morphological details and photographic images, which will help with their identification in future studies. We also review their ecological preferences to aid future (palaeo)ecological and (palaeo)environmental studies. The planktonic assemblage shows a high degree of endemism related to the strong influence of the sea-ice system over Site U1357. In addition, we found the remains of various species of detritus feeders and bottom-dwelling scavengers (benthic foraminifers and annelid worms) indicative of high export productivity at Site U1357. This study shows the potential of organic microfossil remains for reconstructing past environmental conditions, such as sea-ice cover and (export) productivity.
{"title":"A review of the ecological affinities of marine organic microfossils from a Holocene record offshore of Adélie Land (East Antarctica)","authors":"J. Hartman, P. Bijl, F. Sangiorgi","doi":"10.5194/JM-37-445-2018","DOIUrl":"https://doi.org/10.5194/JM-37-445-2018","url":null,"abstract":"Abstract. Integrated Ocean Drilling Program (IODP) Expedition 318 recovered a ∼ 170 m long Holocene organic-rich sedimentary sequence at Site U1357. Located within the narrow but deep Adélie Basin close to the Antarctic margin, the site accumulated sediments at exceptionally high sedimentation rates, which resulted in extraordinary preservation of the organic sedimentary component. Here, we present an overview of 74 different mainly marine microfossil taxa and/or types found within the organic component of the sediment, which include the remains of unicellular and higher organisms from three eukaryotic kingdoms (Chromista, Plantae, and Animalia). These remains include phytoplanktonic (phototrophic dinoflagellates and prasinophytes) and very diverse zooplanktonic (heterotrophic dinoflagellates, tintinnids, copepods) organisms. We illustrate each marine microfossil taxon or type identified by providing morphological details and photographic images, which will help with their identification in future studies. We also review their ecological preferences to aid future (palaeo)ecological and (palaeo)environmental studies. The planktonic assemblage shows a high degree of endemism related to the strong influence of the sea-ice system over Site U1357. In addition, we found the remains of various species of detritus feeders and bottom-dwelling scavengers (benthic foraminifers and annelid worms) indicative of high export productivity at Site U1357. This study shows the potential of organic microfossil remains for reconstructing past environmental conditions, such as sea-ice cover and (export) productivity.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-10-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49210186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Isabel S. Fenton, U. Baranowski, F. Boscolo-Galazzo, Hannah Cheales, Lyndsey R. Fox, David J. King, Christina S. Larkin, Marcin Latas, D. Liebrand, C. Miller, K. Nilsson-Kerr, E. Piga, H. Pugh, Serginio R. C. Remmelzwaal, Zoë A. Roseby, Yvonne. Smith, Stephen Stukins, B. Taylor, A. Woodhouse, Savannah Worne, P. Pearson, C. R. Poole, B. Wade, A. Purvis
Abstract. Planktonic foraminifera are widely used in biostratigraphic, palaeoceanographic and evolutionary studies, but the strength of many study conclusions could be weakened if taxonomic identifications are not reproducible by different workers. In this study, to assess the relative importance of a range of possible reasons for among-worker disagreement in identification, 100 specimens of 26 species of macroperforate planktonic foraminifera were selected from a core-top site in the subtropical Pacific Ocean. Twenty-three scientists at different career stages – including some with only a few days experience of planktonic foraminifera – were asked to identify each specimen to species level, and to indicate their confidence in each identification. The participants were provided with a species list and had access to additional reference materials. We use generalised linear mixed-effects models to test the relevance of three sets of factors in identification accuracy: participant-level characteristics (including experience), species-level characteristics (including a participant's knowledge of the species) and specimen-level characteristics (size, confidence in identification). The 19 less experienced scientists achieve a median accuracy of 57 %, which rises to 75 % for specimens they are confident in. For the 4 most experienced participants, overall accuracy is 79 %, rising to 93 % when they are confident. To obtain maximum comparability and ease of analysis, everyone used a standard microscope with only 35× magnification, and each specimen was studied in isolation. Consequently, these data provide a lower limit for an estimate of consistency. Importantly, participants could largely predict whether their identifications were correct or incorrect: their own assessments of specimen-level confidence and of their previous knowledge of species concepts were the strongest predictors of accuracy.
{"title":"Factors affecting consistency and accuracy in identifying modern macroperforate planktonic foraminifera","authors":"Isabel S. Fenton, U. Baranowski, F. Boscolo-Galazzo, Hannah Cheales, Lyndsey R. Fox, David J. King, Christina S. Larkin, Marcin Latas, D. Liebrand, C. Miller, K. Nilsson-Kerr, E. Piga, H. Pugh, Serginio R. C. Remmelzwaal, Zoë A. Roseby, Yvonne. Smith, Stephen Stukins, B. Taylor, A. Woodhouse, Savannah Worne, P. Pearson, C. R. Poole, B. Wade, A. Purvis","doi":"10.5194/JM-37-431-2018","DOIUrl":"https://doi.org/10.5194/JM-37-431-2018","url":null,"abstract":"Abstract. Planktonic foraminifera are widely used in biostratigraphic,\u0000palaeoceanographic and evolutionary studies, but the strength of many\u0000study conclusions could be weakened if taxonomic identifications are not\u0000reproducible by different workers. In this study, to assess the relative\u0000importance of a range of possible reasons for among-worker disagreement in\u0000identification, 100 specimens of 26 species of macroperforate planktonic\u0000foraminifera were selected from a core-top site in the subtropical Pacific\u0000Ocean. Twenty-three scientists at different career stages – including some\u0000with only a few days experience of planktonic foraminifera – were asked to\u0000identify each specimen to species level, and to indicate their confidence in each\u0000identification. The participants were provided with a species list and had\u0000access to additional reference materials. We use generalised linear\u0000mixed-effects models to test the relevance of three sets of factors in\u0000identification accuracy: participant-level characteristics (including\u0000experience), species-level characteristics (including a participant's\u0000knowledge of the species) and specimen-level characteristics (size,\u0000confidence in identification). The 19 less experienced scientists achieve a\u0000median accuracy of 57 %, which rises to 75 % for specimens they are\u0000confident in. For the 4 most experienced participants, overall accuracy is\u000079 %, rising to 93 % when they are confident. To obtain maximum\u0000comparability and ease of analysis, everyone used a standard microscope with\u0000only 35× magnification, and each specimen was studied in isolation.\u0000Consequently, these data provide a lower limit for an estimate of\u0000consistency. Importantly, participants could largely predict whether their\u0000identifications were correct or incorrect: their own assessments of\u0000specimen-level confidence and of their previous knowledge of species concepts\u0000were the strongest predictors of accuracy.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48315321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Groeneveld, H. Filipsson, W. Austin, K. Darling, D. McCarthy, N. Q. Quintana Krupinski, C. Bird, M. Schweizer
Abstract. Current climate and environmental changes strongly affect shallow marine and coastal areas like the Baltic Sea. This has created a need for a context to understand the severity and potential outcomes of such changes. The context can be derived from paleoenvironmental records during periods when comparable events happened in the past. In this study, we explore how varying bottom water conditions across a large hydrographic gradient in the Baltic Sea affect benthic foraminiferal faunal assemblages and the geochemical composition of their calcite tests. We have conducted both morphological and molecular analyses of the faunas and we evaluate how the chemical signatures of the bottom waters are recorded in the tests of several species of benthic foraminifera. We focus on two locations, one in the Kattegat (western Baltic Sea) and one in Hanö Bay (southern Baltic Sea). We show that seawater Mn∕Ca, Mg∕Ca, and Ba∕Ca (Mn∕Casw, Mg∕Casw, and Ba∕Casw) variations are mainly controlled by dissolved oxygen concentration and salinity. Their respective imprints on the foraminiferal calcite demonstrate the potential of Mn∕Ca as a proxy for hypoxic conditions, and Ba∕Ca as a proxy for salinity in enclosed basins such as the Baltic Sea. The traditional use of Mg∕Ca as a proxy to reconstruct past seawater temperatures is not recommended in the region, as it may be overprinted by the large variations in salinity (specifically on Bulimina marginata), Mg∕Casw, and possibly also the carbonate system. Salinity is the main factor controlling the faunal assemblages: a much more diverse fauna occurs in the higher-salinity (∼32) Kattegat than in the low-salinity (∼15) Hanö Bay. Molecular identification shows that only Elphidium clavatum occurs at both locations, but other genetic types of both genera Elphidium and Ammonia are restricted to either low- or high-salinity locations. The combination of foraminiferal geochemistry and environmental parameters demonstrates that in a highly variable setting like the Baltic Sea, it is possible to separate different environmental impacts on the foraminiferal assemblages and therefore use Mn∕Ca, Mg∕Ca, and Ba∕Ca to reconstruct how specific conditions may have varied in the past.
{"title":"Assessing proxy signatures of temperature, salinity, and hypoxia in the Baltic Sea through foraminifera-based geochemistry and faunal assemblages","authors":"J. Groeneveld, H. Filipsson, W. Austin, K. Darling, D. McCarthy, N. Q. Quintana Krupinski, C. Bird, M. Schweizer","doi":"10.5194/JM-37-403-2018","DOIUrl":"https://doi.org/10.5194/JM-37-403-2018","url":null,"abstract":"Abstract. Current climate and environmental changes strongly affect shallow marine and coastal\u0000areas like the Baltic Sea. This has created a need for a context to\u0000understand the severity and potential outcomes of such changes. The context\u0000can be derived from paleoenvironmental records during periods when comparable\u0000events happened in the past. In this study, we explore how varying bottom\u0000water conditions across a large hydrographic gradient in the Baltic Sea\u0000affect benthic foraminiferal faunal assemblages and the geochemical\u0000composition of their calcite tests. We have conducted both morphological and\u0000molecular analyses of the faunas and we evaluate how the chemical signatures\u0000of the bottom waters are recorded in the tests of several species of benthic\u0000foraminifera. We focus on two locations, one in the Kattegat (western Baltic\u0000Sea) and one in Hanö Bay (southern Baltic Sea). We show that seawater\u0000Mn∕Ca, Mg∕Ca, and Ba∕Ca\u0000(Mn∕Casw, Mg∕Casw, and Ba∕Casw)\u0000variations are mainly controlled by dissolved oxygen concentration and\u0000salinity. Their respective imprints on the foraminiferal calcite demonstrate\u0000the potential of Mn∕Ca as a proxy for hypoxic conditions, and Ba∕Ca as a\u0000proxy for salinity in enclosed basins such as the Baltic Sea. The traditional\u0000use of Mg∕Ca as a proxy to reconstruct past seawater temperatures is not\u0000recommended in the region, as it may be overprinted by the large variations\u0000in salinity (specifically on Bulimina marginata), Mg∕Casw, and\u0000possibly also the carbonate system. Salinity is the main factor controlling\u0000the faunal assemblages: a much more diverse fauna occurs in the higher-salinity (∼32) Kattegat than in the low-salinity\u0000(∼15) Hanö Bay. Molecular identification shows that only\u0000Elphidium clavatum occurs at both locations, but other genetic types\u0000of both genera Elphidium and Ammonia are restricted to\u0000either low- or high-salinity locations. The combination of foraminiferal\u0000geochemistry and environmental parameters demonstrates that in a highly\u0000variable setting like the Baltic Sea, it is possible to separate different\u0000environmental impacts on the foraminiferal assemblages and therefore use\u0000Mn∕Ca, Mg∕Ca, and Ba∕Ca to reconstruct how specific conditions may have\u0000varied in the past.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46797865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Benthic foraminifera from Bottsand coastal lagoon, western Baltic Sea, have been studied since the mid-1960s. They were monitored annually in late autumn since 2003 at the terminal ditch of the lagoon. There were 12 different species recognised, of which three have not been recorded during earlier investigations. Dominant species showed strong interannual fluctuations and a steady increase in population densities over the last decade. Elphidium incertum, a stenohaline species of the Baltic deep water fauna, colonised the Bottsand lagoon in 2016, most likely during a period of salinities >19 units and water temperatures of 18 ∘ C on average in early autumn. The high salinities probably triggered their germination from a propagule bank in the ditch bottom sediment. The new E. incertum population showed densities higher by an order of magnitude than those of the indigenous species. The latter did not decline, revealing that E. incertum used another food source or occupied a different microhabitat. Elphidium incertum survived transient periods of lower salinities in late autumn 2017, though with reduced abundances, and became a regular faunal constituent at the Bottsand lagoon.
{"title":"Monitoring benthic foraminiferal dynamics at Bottsand coastal lagoon (western Baltic Sea)","authors":"J. Schönfeld","doi":"10.5194/JM-37-383-2018","DOIUrl":"https://doi.org/10.5194/JM-37-383-2018","url":null,"abstract":"Abstract. Benthic foraminifera from\u0000Bottsand coastal lagoon, western Baltic Sea, have been studied since the\u0000mid-1960s. They were monitored annually in late autumn since 2003 at the\u0000terminal ditch of the lagoon. There were 12 different species recognised, of\u0000which three have not been recorded during earlier investigations. Dominant\u0000species showed strong interannual fluctuations and a steady increase in\u0000population densities over the last decade. Elphidium incertum, a\u0000stenohaline species of the Baltic deep water fauna, colonised the Bottsand\u0000lagoon in 2016, most likely during a period of salinities >19\u0000units and water temperatures of 18 ∘ C on average in early autumn.\u0000The high salinities probably triggered their germination from a propagule\u0000bank in the ditch bottom sediment. The new E. incertum population\u0000showed densities higher by an order of magnitude than those of the indigenous\u0000species. The latter did not decline, revealing that E. incertum used\u0000another food source or occupied a different microhabitat. Elphidium incertum survived transient periods of lower salinities in late autumn 2017,\u0000though with reduced abundances, and became a regular faunal constituent at\u0000the Bottsand lagoon.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48720500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Özcan, J. Pignatti, Christer Dominique Pereira, A. O. Yücel, K. Drobne, F. Barattolo, P. Saraswati
Abstract. The late Paleocene orthophragminids, hitherto poorly known from the Himalayan foreland basins, are studied from the Lakadong Limestone in Meghalaya, northeastern India, in order to establish a systematic, biostratigraphic, and paleobiogeographical framework for them in the eastern Tethys. In the Mawmluh Quarry section (MQS) on the Shillong Plateau, to the southeast of Tibet, orthophragminids are associated with typical Paleocene orbitoidiform taxa endemic to the Indian subcontinent, i.e., Lakadongia Matsumaru & Jauhri ( = Setia Ferrandez-Canadell) and Orbitosiphon Rao, and various species of alveolinids, miscellaneids, and rotaliids, characterizing the Shallow Benthic Zones (SBZ) 3 and 4. The orthophragminids belong to two lineages of the genus Orbitoclypeus Silvestri: O. schopeni (Checchia-Rispoli) and O. multiplicatus (Gumbel), both well known from the peri-Mediterranean region and Europe (western Tethys). The latter species is identified here for the first time from the eastern Tethys. Previous records of the genus Discocyclina Gumbel from the Lakadong Limestone actually correspond to misidentified Orbitoclypeus; this implies that the late Paleocene orthophragminid assemblages from Meghalaya and eastern Tethys were less diverse than in the western Tethys. The lineage of Orbitoclypeus schopeni in the lower part of the Lakadong Limestone (SBZ 3) is identified as O. schopeni cf. ramaraoi based on the morphometry of a few specimens, whereas in the upper part (SBZ 4) it corresponds to a transitional development stage between O. schopeni ramaraoi and O. schopeni neumannae (with average Dmean values ranging between 192 and 199 µm ). The embryon diameters of O. multiplicatus, recorded only in SBZ 4, range between 300 and 319 µm on average, corresponding to transitional development stages of O. multiplicatus haymanaensis and O. multiplicatus multiplicatus. Our data, along with a review of previous Paleocene and Eocene records from India and Pakistan, suggest that Orbitoclypeus is the only orthophragminid in the Paleocene of the eastern Tethys, whereas Discocyclina first appears in early Eocene times, being mainly represented by endemic taxa confined to the Indian subcontinent. Facies change in the MQS from a marine to continental setting within SBZ 4 corresponds to the oldest record from the Indian plate in the Paleogene, which may be linked to the flexural uplift of the passive margin of the Indian plate, marking the onset of the collision of the Indian and Eurasian plates.
{"title":"Paleocene orthophragminids from the Lakadong Limestone, Mawmluh Quarry section, Meghalaya (Shillong, NE India): implications for the regional geology and paleobiogeography","authors":"E. Özcan, J. Pignatti, Christer Dominique Pereira, A. O. Yücel, K. Drobne, F. Barattolo, P. Saraswati","doi":"10.5194/JM-37-357-2018","DOIUrl":"https://doi.org/10.5194/JM-37-357-2018","url":null,"abstract":"Abstract. The late Paleocene orthophragminids, hitherto poorly known\u0000from the Himalayan foreland basins, are studied from the Lakadong Limestone\u0000in Meghalaya, northeastern India, in order to establish a systematic,\u0000biostratigraphic, and paleobiogeographical framework for them in the eastern\u0000Tethys. In the Mawmluh Quarry section (MQS) on the Shillong Plateau, to the\u0000southeast of Tibet, orthophragminids are associated with typical Paleocene\u0000orbitoidiform taxa endemic to the Indian subcontinent, i.e.,\u0000Lakadongia Matsumaru & Jauhri ( = Setia\u0000Ferrandez-Canadell) and Orbitosiphon Rao, and various\u0000species of alveolinids, miscellaneids, and rotaliids, characterizing the\u0000Shallow Benthic Zones (SBZ) 3 and 4. The orthophragminids belong to two\u0000lineages of the genus Orbitoclypeus Silvestri: O. schopeni\u0000(Checchia-Rispoli) and O. multiplicatus (Gumbel), both\u0000well known from the peri-Mediterranean region and Europe (western Tethys).\u0000The latter species is identified here for the first time from the eastern\u0000Tethys. Previous records of the genus Discocyclina Gumbel from\u0000the Lakadong Limestone actually correspond to misidentified\u0000Orbitoclypeus; this implies that the late Paleocene orthophragminid\u0000assemblages from Meghalaya and eastern Tethys were less diverse than in the\u0000western Tethys. The lineage of Orbitoclypeus schopeni in the lower\u0000part of the Lakadong Limestone (SBZ 3) is identified as O. schopeni cf. ramaraoi\u0000based on the morphometry of a few specimens, whereas in the\u0000upper part (SBZ 4) it corresponds to a transitional development stage between\u0000O. schopeni ramaraoi and O. schopeni neumannae (with\u0000average Dmean values ranging between 192 and 199 µm ). The\u0000embryon\u0000diameters of O. multiplicatus, recorded only in SBZ 4, range between\u0000300 and 319 µm on average, corresponding to transitional development\u0000stages of O. multiplicatus haymanaensis and O. multiplicatus multiplicatus. Our data, along with a review of previous Paleocene and\u0000Eocene records from India and Pakistan, suggest that Orbitoclypeus\u0000is the only orthophragminid in the Paleocene of the eastern Tethys, whereas\u0000Discocyclina first appears in early Eocene times, being mainly\u0000represented by endemic taxa confined to the Indian subcontinent. Facies change in the MQS\u0000from a marine to continental setting within SBZ 4 corresponds to the oldest record from\u0000the Indian plate in the Paleogene, which may be linked to the flexural uplift of the passive margin\u0000of the Indian plate, marking the onset of the collision of the Indian and Eurasian plates.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49368942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Shallow-water carbonate deposits are well-known from the Eocene of the US Gulf Coast and Caribbean. These deposits frequently contain abundant larger benthic foraminifera (LBF). However, whilst integrated stratigraphic studies have helped to refine the timing of LBF overturning events within the Tethys and Indo-Pacific regions with respect to global bio- and chemo-stratigraphic records, little recent work has been carried out in the Americas. The American LBF assemblages are distinctly different from those of Europe and the Indo-Pacific. It is therefore essential that the American bio-province is included in studies of LBF evolution, biodiversity and climate events to understand these processes on a global scale. Here we present the LBF ranges from two previously unpublished sections spanning 35 and 29 m of the upper Eocene Ocala limestone, as the early stages of a larger project addressing the taxonomy and biostratigraphy of the LBF of Florida. The study indicates that the lower member of the Ocala limestone may be Bartonian rather than Priabonian in age, with implications for the biostratigraphy of the region. In addition, the study highlights the need for multiple sites to assess the LBF assemblages and fully constrain ranges across Florida and the US Gulf and suggests potential LBF events for future integrated stratigraphic study.
{"title":"Larger foraminifera of the Devil's Den and Blue Hole sinkholes, Florida","authors":"L. Cotton, W. Eder, J. Floyd","doi":"10.5194/JM-37-347-2018","DOIUrl":"https://doi.org/10.5194/JM-37-347-2018","url":null,"abstract":"Abstract. Shallow-water carbonate deposits are well-known from the Eocene of the US\u0000Gulf Coast and Caribbean. These deposits frequently contain abundant larger\u0000benthic foraminifera (LBF). However, whilst integrated stratigraphic studies\u0000have helped to refine the timing of LBF overturning events within the Tethys\u0000and Indo-Pacific regions with respect to global bio- and chemo-stratigraphic\u0000records, little recent work has been carried out in the Americas. The\u0000American LBF assemblages are distinctly different from those of Europe and\u0000the Indo-Pacific. It is therefore essential that the American bio-province is\u0000included in studies of LBF evolution, biodiversity and climate events to\u0000understand these processes on a global scale. Here we present the LBF ranges from two previously unpublished sections\u0000spanning 35 and 29 m of the upper Eocene Ocala limestone, as the early\u0000stages of a larger project addressing the taxonomy and biostratigraphy of the\u0000LBF of Florida. The study indicates that the lower\u0000member of the Ocala\u0000limestone may be Bartonian rather than Priabonian in age, with implications\u0000for the biostratigraphy of the region. In addition, the study highlights the\u0000need for multiple sites to assess the LBF assemblages and fully constrain\u0000ranges across Florida and the US Gulf and suggests potential LBF events for\u0000future integrated stratigraphic study.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42201927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract. Wangshangkia, a new genus of Ostracoda, from the Late Devonian in Dushan of Guizhou, South China, is described. This genus belongs to the family Bairdiocyprididae Shaver, 1961 and includes two new species, i.e. Wangshangkia dushaniensis and W . bailouiensis. The new genus is characterized by a wide ventral carina with radial striae. It is reported from the Famennian of South China and disappeared just below the Devonian-Carboniferous boundary. Wangshangkia is essentially a benthic crawler and is restricted to the shallow-marine depositional environment with a low hydrodynamic condition. Wangshangkia: urn:lsid:zoobank.org:act:34BF01D4-D202-492D-8E27-BC508EF7EFFB W. dushaniensis: urn:lsid:zoobank.org:act:D267C362-7510-4D19-996B-EA1848D7D025 W. bailouiensis: urn:lsid:zoobank.org:act:FE988AA0-7363-4D9E-A5AB-1526C8DBCDD9
{"title":"Wangshangkia, a new Devonian ostracod genus from Dushan of Guizhou, South China","authors":"Junjun Song, Y. Gong","doi":"10.5194/JM-37-341-2018","DOIUrl":"https://doi.org/10.5194/JM-37-341-2018","url":null,"abstract":"Abstract. Wangshangkia, a new genus of Ostracoda, from the Late\u0000Devonian in Dushan of Guizhou, South China, is described. This genus belongs to the family\u0000Bairdiocyprididae Shaver, 1961 and includes two new species, i.e.\u0000Wangshangkia dushaniensis and W . bailouiensis. The new\u0000genus is characterized by a wide ventral carina with radial striae. It is\u0000reported from the Famennian of South China and disappeared just below the\u0000Devonian-Carboniferous boundary. Wangshangkia is essentially a\u0000benthic crawler and is restricted to the shallow-marine depositional\u0000environment with a low hydrodynamic condition. Wangshangkia:\u0000urn:lsid:zoobank.org:act:34BF01D4-D202-492D-8E27-BC508EF7EFFB W. dushaniensis: urn:lsid:zoobank.org:act:D267C362-7510-4D19-996B-EA1848D7D025 W. bailouiensis: urn:lsid:zoobank.org:act:FE988AA0-7363-4D9E-A5AB-1526C8DBCDD9","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2018-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41763518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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