Journal of Micropalaeontology最新文献

{"title":"Identification of the Paleocene–Eocene boundary in coastal strata in the Otway Basin, Victoria, Australia","authors":"J. Frieling, E. Huurdeman, Charlotte C M Rem, T. Donders, J. Pross, S. Bohaty, G. Holdgate, S. Gallagher, B. Mcgowran, P. Bijl","doi":"10.5194/JM-37-317-2018","DOIUrl":"https://doi.org/10.5194/JM-37-317-2018","url":null,"abstract":"Abstract. Detailed, stratigraphically well-constrained environmental reconstructions\u0000are available for Paleocene and Eocene strata at a range of sites in the\u0000southwest Pacific Ocean (New Zealand and East Tasman Plateau; ETP) and\u0000Integrated Ocean Discovery Program (IODP) Site U1356 in the south of the\u0000Australo-Antarctic Gulf (AAG). These reconstructions have revealed a large\u0000discrepancy between temperature proxy data and climate models in this region,\u0000suggesting a crucial error in model, proxy data or both. To resolve the\u0000origin of this discrepancy, detailed reconstructions are needed from both\u0000sides of the Tasmanian Gateway. Paleocene–Eocene sedimentary archives from\u0000the west of the Tasmanian Gateway have unfortunately remained scarce (only\u0000IODP Site U1356), and no well-dated successions are available for the\u0000northern sector of the AAG. Here we present new stratigraphic data for upper\u0000Paleocene and lower Eocene strata from the Otway Basin, southeast Australia,\u0000on the (north)west side of the Tasmanian Gateway. We analyzed sediments\u0000recovered from exploration drilling (Latrobe-1 drill core) and outcrop\u0000sampling (Point Margaret) and performed high-resolution carbon isotope\u0000geochemistry of bulk organic matter and dinoflagellate cyst (dinocyst) and\u0000pollen biostratigraphy on sediments from the regional lithostratigraphic\u0000units, including the Pebble Point Formation, Pember Mudstone and Dilwyn\u0000Formation. Pollen and dinocyst assemblages are assigned to previously\u0000established Australian pollen and dinocyst zonations and tied to available\u0000zonations for the SW Pacific. Based on our dinocyst stratigraphy and\u0000previously published planktic foraminifer biostratigraphy, the Pebble Point\u0000Formation at Point Margaret is dated to the latest Paleocene. The globally\u0000synchronous negative carbon isotope excursion that marks the\u0000Paleocene–Eocene boundary is identified within the top part of the Pember\u0000Mudstone in the Latrobe-1 borehole and at Point Margaret. However, the high abundances of the\u0000dinocyst Apectodinium prior to this negative carbon isotope\u0000excursion prohibit a direct correlation of this regional bio-event with the\u0000quasi-global Apectodinium acme at the Paleocene–Eocene Thermal\u0000Maximum (PETM; 56  Ma ). Therefore, the first occurrence of the pollen\u0000species Spinizonocolpites prominatus and the dinocyst species\u0000Florentinia reichartii are here designated as regional markers for\u0000the PETM. In the Latrobe-1 drill core, dinocyst biostratigraphy further\u0000indicates that the early Eocene ( ∼  56–51  Ma ) sediments are\u0000truncated by a ∼  10  Myr long hiatus overlain by middle Eocene\u0000( ∼  40  Ma ) strata. These sedimentary archives from southeast\u0000Australia may prove key in resolving the model–data discrepancy in this\u0000region, and the new stratigraphic data presented here allow for detailed\u0000comparisons between paleoclimate records on both sides of the Tasmanian\u0000Gateway.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"317-339"},"PeriodicalIF":2.0,"publicationDate":"2018-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49326870","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}

{"title":"Micropalaeontological dating of the basal Cretaceous section of DSDP Site 249, Leg 25, Mozambique Ridge: implications for the timing of the southern Atlantic–Indian Ocean connection","authors":"R. Dunay, W. Braham, M. K. E. Cooper, Martin Lester, F. Tremolada","doi":"10.5194/JM-37-305-2018","DOIUrl":"https://doi.org/10.5194/JM-37-305-2018","url":null,"abstract":"Abstract. Tectonic models suggest the absence of a deep water connection on the\u0000Mozambique Ridge during early Neocomian time. These models imply the\u0000initiation of a deep water connection between the southern Atlantic and\u0000Indian oceans formed during Barremian–earliest Aptian times. However,\u0000previous biostratigraphic studies of the earliest deep water sediments on the\u0000Mozambique Ridge suggest that the basal section is Neocomian in age. Here, we\u0000present a new biostratigraphic analysis undertaken to test this tectonic\u0000model and determine the earliest age of deep water sedimentation on the\u0000Mozambique Ridge. Core samples from the Cretaceous interval\u0000222.05–406.32  m (Cores 19–32) of DSDP Site 249, Leg 25, were\u0000sampled for calcareous nannoplankton and palynological analysis. Most of the\u0000sampling was concentrated on the Lower Cretaceous interval below\u0000294  m . Our results indicate that the lower sedimentary section is no\u0000older than Barremian and therefore provides support for the age proposed by\u0000the tectonic models.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"305-316"},"PeriodicalIF":2.0,"publicationDate":"2018-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46097777","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}

{"title":"On a grain of sand – a microhabitat for the opportunistic agglutinated foraminifera Hemisphaerammina apta n. sp., from the early Eocene Arctic Ocean","authors":"D. McNeil, L. Neville","doi":"10.5194/JM-37-295-2018","DOIUrl":"https://doi.org/10.5194/JM-37-295-2018","url":null,"abstract":"Abstract. Hemisphaerammina apta n. sp. is an attached monothalamous agglutinated foraminifera discovered in shelf sediments of the early Eocene Arctic Ocean. It is a simple yet distinctive component of the endemic agglutinated foraminiferal assemblage that colonized the Arctic Ocean after the microfaunal turnover caused by the Paleocene–Eocene Thermal Maximum. Associated foraminifera are characterized by a high percentage of monothalamous species (up to 60 %) and are entirely agglutinated indicating a brackish (mesohaline) early Eocene Arctic Ocean. Hemisphaerammina apta occurs exclusively as individuals attached to fine detrital grains (0.2 to 1.8 mm) of sediment. It is a small species (0.06 to 0.2 mm in diameter), fine-grained, with a low hemispherical profile, no floor across the attachment area, no substantive marginal flange, no internal structures, and no aperture. Lacking an aperture, it apparently propagated and fed through minute (micrometre-sized) interstitial pores in the test wall. Attachment surfaces vary from concave to convex and rough to smooth. Grains for attachment are diverse in shape and type but are predominantly of quartz and chert. The presence of H. apta in the early Eocene was an opportunistic response to an environment with an active hydrological system (storm events). Attachment to grains of sand would provide a more stable base on a sea floor winnowed by storm-generated currents. Active transport is indicated by the relative abundance of reworked foraminifera mixed with in situ species. Contemporaneous reworking and colonization by H. apta is suggested by its attachment to a reworked specimen of Cretaceous foraminifera.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"295-303"},"PeriodicalIF":2.0,"publicationDate":"2018-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48310618","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}

{"title":"Morphometric analysis of early Eocene Corbisema skeletons (Silicoflagellata) in Mors, Denmark","authors":"H. Tsutsui, R. Jordan, N. Nishiwaki, S. Nishida","doi":"10.5194/JM-37-283-2018","DOIUrl":"https://doi.org/10.5194/JM-37-283-2018","url":null,"abstract":"Abstract. A two-dimensional morphometric programme, recently designed to measure fossil\u0000skeletons of the silicoflagellate genus Corbisema, was used to\u0000investigate specimens of the C. apiculata–C. triacantha\u0000complex found in a sample from the Fur Formation on the island of Mors,\u0000Jutland, Denmark. The semi-automated programme measured the lengths of the\u0000basal sides and radial spines, the basal side curvature, and the location of\u0000the pikes (if present) from a photographic database ( N=469 ). As a result,\u0000two distinct morphological groups were revealed based on their radial spine\u0000length : basal side length ratio and the presence or absence of pikes: group A\u0000(ratio of 1 : 1.3, no pikes) and group B, with the latter subdivided into\u0000B1 (ratio of 1 : 7, with pikes) and B2 (ratio of 1 : 6, no pikes).\u0000Group A (C. triacantha sensu lato) possesses a small basal ring with\u0000relatively straight basal sides and long radial spines, while group B has a\u0000large basal ring with curved basal sides and short radial spines. In B1\u0000specimens (C. apiculata sensu stricto) the pikes are positioned 0 to\u00001  µ m away from the junction point of the strut and basal ring. This\u0000would suggest that B1 double skeletons are likely to be in the Star-of-David\u0000configuration, while A and B2 double skeletons (which lack pikes) are likely\u0000to be in the corner-to-corner configuration. Compared with the previously\u0000published biometric studies of extant Stephanocha\u0000(Stephanocha speculum complex in the Southern Ocean and S. medianoctisol in the Arctic Ocean), the results are somewhat different:\u0000although C. triacantha sensu lato (group A) is similar to the modern\u0000species of Stephanocha, the latter have smaller basal ring\u0000diameters, whereas specimens of C. apiculata sensu lato (types B1\u0000and B2) have large basal rings. If their cell diameters are calculated, B1 is\u0000the largest, with S. speculum being the smallest – about half the\u0000size of B1. This could suggest that the relationship between radial spine\u0000length and mean basal ring size has shifted over geological time.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"283-293"},"PeriodicalIF":2.0,"publicationDate":"2018-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45026841","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}

{"title":"Modified cleaning method for biomineralized components","authors":"H. Tsutsui, R. Jordan","doi":"10.5194/JM-37-249-2018","DOIUrl":"https://doi.org/10.5194/JM-37-249-2018","url":null,"abstract":"Abstract. The extraction and concentration of biomineralized components from sediment\u0000or living materials is time consuming and laborious and often involves steps\u0000that remove either the calcareous or siliceous part, in addition to organic\u0000matter. However, a relatively quick and easy method using a commercial\u0000cleaning fluid for kitchen drains, sometimes combined with a kerosene soaking\u0000step, can produce remarkable results. In this study, the method is applied to\u0000sediments and living materials bearing calcareous (e.g., coccoliths,\u0000foraminiferal tests, holothurian ossicles, ichthyoliths, and fish otoliths)\u0000and siliceous (e.g., diatom valves, silicoflagellate skeletons, and sponge\u0000spicules) components. The method preserves both components in the same\u0000sample, without etching or partial dissolution, but is not applicable to\u0000unmineralized components such as dinoflagellate thecae, tintinnid loricae,\u0000pollen, or plant fragments.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"249-256"},"PeriodicalIF":2.0,"publicationDate":"2018-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45278917","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}

{"title":"Ostracods (Crustacea) as shelf to basin indicators: evidence from Late Devonian Yangdi and Nandong sections in Guangxi, South China","authors":"Junjun Song, Junjun Song, Junjun Song, S. Crasquin, Y. Gong","doi":"10.5194/JM-37-257-2018","DOIUrl":"https://doi.org/10.5194/JM-37-257-2018","url":null,"abstract":"Abstract. Forty-eight ostracod species belonging to 28 genera from the Late Devonian of\u0000Guangxi in South China are described and figured. The ostracod assemblage\u0000from the Nandong section can be attributed to the\u0000rhenana–linguiformis conodont zones. The ecological assemblages of\u0000ostracods from the Yangdi section correspond to a smooth-podocopid\u0000association accompanied by some pelagic entomozoids. This mixed assemblage is\u0000indicative of an environment of carbonate platform to slope during an ongoing\u0000regression. The ostracod faunas from the Nandong section are on the contrary\u0000composed of both pelagic and benthic ostracods and pelagic forms dominate in\u0000number of specimens suggesting a basin environment.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"257-281"},"PeriodicalIF":2.0,"publicationDate":"2018-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48495653","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}

{"title":"A brief warming event in the late Albian: evidence from calcareous nannofossils, macrofossils, and isotope geochemistry of the Gault Clay Formation, Folkestone, southeastern England","authors":"S. Kanungo, P. Bown, J. Young, A. Gale","doi":"10.5194/JM-37-231-2018","DOIUrl":"https://doi.org/10.5194/JM-37-231-2018","url":null,"abstract":"Abstract. This\u0000paper documents a warming event across the middle–upper Albian interval in a\u0000 ∼  22 m long section from the Gault Clay Formation of Copt Point,\u0000Folkestone (UK). Evidence for the event comes from three independent\u0000datasets: calcareous nannofossils, ammonites, and the bulk sediment carbon\u0000and oxygen stable isotope record, which collectively indicate a brief period\u0000( ∼  500 kyr) of significant surface water warming (in excess of\u00006  ∘ C) at around 107.5 Ma (the base of the Dipoloceras cristatum Ammonite Zone). A surface water productivity increase based on\u0000high percentages of the eutrophic nannofossil Zeugrhabdotus noeliae\u0000is found to be concomitant with this warming event, suggesting that surface\u0000waters were nutrient-rich and the warming was associated with increased\u0000precipitation and run-off, delivering more nutrients into the basin.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"231-247"},"PeriodicalIF":2.0,"publicationDate":"2018-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41938891","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}

{"title":"Benthic foraminifera or Ostracoda? Comparing the accuracy of palaeoenvironmental indicators from a Pleistocene lagoon of the Romagna coastal plain (Italy)","authors":"G. Barbieri, S. Vaiani","doi":"10.5194/JM-37-203-2018","DOIUrl":"https://doi.org/10.5194/JM-37-203-2018","url":null,"abstract":"Abstract. Integrated analyses of multiple groups of microfossils are frequently performed to unravel the palaeoenvironmental evolution of subsurface coastal successions, where the complex interaction among several palaeoecological factors can be detected with benthic assemblages. This work investigates the palaeoenvironmental resolution potential provided by benthic foraminifera and ostracoda within a Pleistocene lagoonal succession of the Romagna coastal plain (northern Italy). Quantitative approaches and statistical techniques have been applied to both groups in order to understand the main factors that controlled the composition of assemblages and compare the palaeoecological record provided by single fossil groups. The two faunal groups are characterized by the high dominance of opportunistic species (Ammonia tepida–Ammonia parkinsoniana and Cyprideis torosa); however, detailed palaeoecological information is inferred from less common taxa. Benthic foraminiferal assemblages are mainly determined by the frequencies of abnormal individuals and species related to high concentrations of organic matter, showing two assemblages: a stressed assemblage, consistent with a brackish-water environment subject to salinity and oxygen fluctuations, and an unstressed assemblage, which indicates more stable conditions. Despite the lower number of species, ostracoda show more significant differences in terms of species composition and ecological structure between their three assemblages, formed in response to a salinity gradient and indicative of inner, central, and outer lagoon conditions. The stratigraphic distribution of ostracod assemblages shows a general transgressive–regressive trend with minor fluctuations, whereas benthic foraminifera highlight the presence of a significant palaeoenvironmental stress. In this case, the higher abundance along the stratigraphic succession, the higher differentiation of the assemblages, and the well-defined relationship between taxa and ecological parameters determine Ostracoda as the most reliable fossil group for precise palaeoenvironmental reconstructions. Nevertheless, benthic foraminifera indicate palaeoenvironmental stress and can be used to refine the environmental interpretation in the presence of monospecific ostracod assemblages.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"203-230"},"PeriodicalIF":2.0,"publicationDate":"2018-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48706463","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}

{"title":"Two new bairdiid ostracod species from the early Barremian–Hauterivian of the northern and central North Sea to the Atlantic margin off Norway","authors":"M. Ayress, T. Gould","doi":"10.5194/JM-37-195-2018","DOIUrl":"https://doi.org/10.5194/JM-37-195-2018","url":null,"abstract":"Abstract. Two new species of bairdiid Ostracoda are described from the lower Barremian\u0000– Hauterivian interval of the Valhall and Asgard formations in the\u0000northern and central North Sea and Atlantic margin off Norway. The new\u0000species are Pontocyprella valhalla\u0000(lsid:zoobank.org:act:CA6B273F-CFF6-4C38-B9F4-18188225A711, 18 January 2018)\u0000and Bairdia asgarda\u0000(lsid:zoobank.org:act:4A4DC817-A028-45FB-9287-ABF3794F2FCB, 18 January 2018).\u0000These species dominate the ostracod assemblage that occurs abundantly in\u0000early Barremian–Hauterivian deep marine sediments of the northern and\u0000central North Sea and Haltenbanken area off Norway. Pontocyprella valhalla is restricted to this interval and because of its large size and\u0000distinct shape is a useful stratigraphic marker species, its last appearance\u0000being within the early Barremian.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"195-201"},"PeriodicalIF":2.0,"publicationDate":"2018-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44717748","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}

{"title":"Cylindroporella sugdeni Elliott, 1957, an Early Cretaceous Middle Eastern Dasycladalean alga – a revision","authors":"B. Granier","doi":"10.5194/JM-37-181-2018","DOIUrl":"https://doi.org/10.5194/JM-37-181-2018","url":null,"abstract":"Abstract. The type material of Cylindroporella sugdeni Elliott, 1957, is\u0000revised. The total lack of sterile laterals and consequently the absence of\u0000the diagnostic feature of the genus Cylindroporella, i.e., the\u0000alternation of sterile and fertile laterals within the same whorl, leads to\u0000its exclusion from the genus Cylindroporella Johnson, 1954, and to\u0000its ascription to the genus Holosporella Pia, 1930. Recent\u0000stratigraphic investigations suggest that the stratum typicum originally\u0000reported as Early Cretaceous in age is more precisely Hauterivian or possibly\u0000Early Barremian in age.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":"37 1","pages":"181-190"},"PeriodicalIF":2.0,"publicationDate":"2018-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49076567","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}