Pub Date : 2019-12-10DOI: 10.25500/EDATA.BHAM.00000411
Dana Ridha, I. Boomer, K. Edgar
Count data for most abundant benthic foraminifera in the late Oligocene-Neogene in ODP Holes 752A, 1139A and 1168A
ODP 752A、1139A和1168A孔晚渐新世—新近纪底栖有孔虫最丰富的计数资料
{"title":"Latest Oligocene to earliest Pliocene deep-sea benthic foraminifera from ODP Sites 752, 1168 and 1139, southern Indian Ocean","authors":"Dana Ridha, I. Boomer, K. Edgar","doi":"10.25500/EDATA.BHAM.00000411","DOIUrl":"https://doi.org/10.25500/EDATA.BHAM.00000411","url":null,"abstract":"Count data for most abundant benthic foraminifera in the late Oligocene-Neogene in ODP Holes 752A, 1139A and 1168A","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45617704","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}
S. Kender, A. Aturamu, J. Zalasiewicz, M. Kaminski, M. Williams
Abstract. The Mid-Brunhes Transition (MBT) saw an increase in the amplitude of glacial cycles expressed in ice core and deep ocean records from about 400 ka, but its influence on high-latitude climates is not fully understood. The Arctic Ocean is thought to have warmed and exhibited reduced sea ice, but little is known of sea ice marginal locations such as the Bering Sea. The Bering Sea is the link between the Arctic and Pacific Ocean and is an area of high productivity and CO2 ventilation; it hosts a pronounced oxygen minimum zone (OMZ) and is thought to be the location of Glacial North Pacific Intermediate Water (GNPIW) formation in the Pleistocene. To understand palaeoceanographic change in the region, we analysed benthic foraminiferal faunas from Bowers Ridge (Site U1342, 800 m of water depth) over the past 600 kyr, as they are uniquely well preserved and sensitive to changes in deep and surface ocean conditions. We identified and imaged 71 taxa and provide a full taxonomy. Foraminiferal preservation is markedly higher during glacials, indicating the presence of less corrosive GNPIW. The most abundant species are Bulimina exilis, Takayanagia delicata, Alabaminella weddellensis, Gyroidina sp. 2, Cassidulina laevigata, Islandiella norcrossi, and Uvigerina bifurcata, consistent with broadly high net primary production throughout the last 600 kyr. Correspondence analysis shows that the most significant Assemblage 1 comprises B. exilis, T. delicata, Bolivina spissa, and Brizalina, which occur sporadically within intervals of laminated, biogenic-rich sediment, mostly during glacials and also some deglacials, and are interpreted as indicating very high productivity. Other assemblages contain the phytodetritivore species A. weddellensis, I. norcrossi, and C. laevigata, indicative of seasonal phytoplankton blooms. Before the MBT, more numerous intervals of the very high-productivity Assemblage 1 and A. weddellensis occur, which we suggest reflect a time of more sea-ice-related seasonal stratification and ice edge blooms. Our inference of a decrease in sea ice meltwater stratification influence in the central Bering Sea after the MBT is consistent with records showing that the Arctic and Pacific Ocean warmed during glacials and suggests that high-latitude productivity and sea ice changes were an important feature of this climate event.
{"title":"Benthic foraminifera indicate Glacial North Pacific Intermediate Water and reduced primary productivity over Bowers Ridge, Bering Sea, since the Mid-Brunhes Transition","authors":"S. Kender, A. Aturamu, J. Zalasiewicz, M. Kaminski, M. Williams","doi":"10.5194/jm-38-177-2019","DOIUrl":"https://doi.org/10.5194/jm-38-177-2019","url":null,"abstract":"Abstract. The Mid-Brunhes Transition (MBT) saw an increase in the amplitude of glacial cycles expressed in ice core and deep ocean records from about 400 ka, but its influence on high-latitude climates is not fully understood. The Arctic Ocean is thought to have warmed and exhibited reduced sea ice, but little is known of sea ice marginal locations such as the Bering Sea. The Bering Sea is the link between the Arctic and Pacific Ocean and is an area of high productivity and CO2 ventilation; it hosts a pronounced oxygen minimum zone (OMZ) and is thought to be the location of Glacial North Pacific Intermediate Water (GNPIW) formation in the Pleistocene. To understand palaeoceanographic change in the region, we analysed benthic foraminiferal faunas from Bowers Ridge (Site U1342, 800 m of water depth) over the past 600 kyr, as they are uniquely well preserved and sensitive to changes in deep and surface ocean conditions. We identified and imaged 71 taxa and provide a full taxonomy. Foraminiferal preservation is markedly higher during glacials, indicating the presence of less corrosive GNPIW. The most abundant species are Bulimina exilis, Takayanagia delicata, Alabaminella weddellensis, Gyroidina sp. 2, Cassidulina laevigata, Islandiella norcrossi, and Uvigerina bifurcata, consistent with broadly high net primary production throughout the last 600 kyr. Correspondence analysis shows that the most significant Assemblage 1 comprises B. exilis, T. delicata, Bolivina spissa, and Brizalina, which occur sporadically within intervals of laminated, biogenic-rich sediment, mostly during glacials and also some deglacials, and are interpreted as indicating very high productivity. Other assemblages contain the phytodetritivore species A. weddellensis, I. norcrossi, and C. laevigata, indicative of seasonal phytoplankton blooms. Before the MBT, more numerous intervals of the very high-productivity Assemblage 1 and A. weddellensis occur, which we suggest reflect a time of more sea-ice-related seasonal stratification and ice edge blooms. Our inference of a decrease in sea ice meltwater stratification influence in the central Bering Sea after the MBT is consistent with records showing that the Arctic and Pacific Ocean warmed during glacials and suggests that high-latitude productivity and sea ice changes were an important feature of this climate event.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46351561","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. The lower Oligocene (Rupelian) successions are climate record archives of the early icehouse world in the Cenozoic. Even though the number of studies focussing on the generally cold Oligocene is increasing, little is known about climatic variations in the mid-latitudes to high latitudes of the Northern Hemisphere. One of the major obstacles is the lack of stratigraphically complete uppermost Eocene to Oligocene successions in these regions. This study focusses on dinoflagellate cysts (dinocysts) from a thick nearly complete Rupelian succession in the Syracuse Oils Norge A/S well 11/10-1 drilled in 1969 in the Norwegian part of the North Sea basin. The well provides a record of mid-latitude dinocyst assemblages, which yield key biostratigraphical and palaeoenvironmental information. All the analyses were undertaken on ditch cutting samples. The dinocyst assemblages confirm that the well penetrates about 600 m of Rupelian sediments and (as supported by correlation with the Nini-1 well) that the lowermost Rupelian (below the top or the last occurrence of Areosphaeridium diktyoplokum) is expanded. These assemblages also indicate the presence of two hiatuses: the first extends from the Lutetian to the Priabonian (equivalent to the D9nb–D12nb zones), and the second spans the Rupelian–Chattian boundary (equivalent to the D14nb subzone or the NSO-5 zone). Despite the risk of caving, the dinocyst assemblages support the existing sequence stratigraphic framework. The assemblages reflect a clear transition from distal to proximal deposition in the vicinity of the site (across the regional seismic sequences OSS-1 – OSS meaning Oligocene seismic sequence – to OSS-2). The proximal deltaic deposits of the OSS-2 regressive system tract (RST) are characterised by pulses of high sea-surface productivity and pronounced shifts in the dinocyst assemblages, reflecting a highly dynamic environment in a restricted marine to marginal marine setting. The Rupelian succession penetrated by well 11/10-1 yields one new species, Areoligera? barskii sp. nov., which is described here in detail. The cold-water-tolerant dinocyst Svalbardella cooksoniae is present in two intervals in the studied succession. These intervals are related to the early Oligocene cooling maxima (the Oi-1a and the Oi-2 events). Furthermore, these two intervals correlate with two local sequence boundaries, suggesting that they are most probably of glacioeustatic origin. From these observations, I postulate that the early icehouse climate played an important role in the depositional development of the Oligocene succession in the North Sea basin. Even though the Eocene–Oligocene transition interval is not complete (i.e. Lutetian to Priabonian is either missing or condensed), well 11/10-1 merits high-resolution studies of the early icehouse climate for the North Sea region. Although any detailed studies should ideally be undertaken on conventional cores instead of ditch cuttings, no such samples spa
摘要下渐新世（卢比安）序列是新生代早期冰库世界的气候记录档案。尽管关注普遍寒冷的渐新世的研究数量正在增加，但人们对北半球中纬度到高纬度的气候变化知之甚少。主要障碍之一是这些地区缺乏地层上完整的最上始新世至渐新世序列。本研究的重点是1969年在北海盆地挪威部分钻探的Syracuse Oils Norge a/S 11/10-1井中厚的、几乎完整的卢比安序列中的甲藻囊肿（甲藻囊肿）。该井提供了中纬度恐龙囊肿组合的记录，提供了关键的生物地层学和古环境信息。所有分析都是对沟渠切割样本进行的。恐龙囊肿组合证实，该井穿透约600 m的卢比安沉积物，以及（与Nini-1井的相关性所支持的）最下面的卢比安（在Aresphaeridium diktyoplokum顶部或最后一次出现的下方）扩展。这些组合还表明存在两个断裂带：第一个断裂带从卢泰阶延伸到普里亚博阶（相当于D9nb–D12nb带），第二个断裂带跨越卢比安-查特阶边界（相当于D14nb亚带或NSO-5带）。尽管存在坍塌的风险，但恐龙囊肿组合支持现有的层序地层格架。组合反映了现场附近从远端沉积到近端沉积的明显过渡（穿过区域地震序列OSS-1-OSS，即渐新世地震序列-OSS-2）。OSS-2海退体系域（RST）的近端三角洲沉积物的特征是海面生产力高的脉冲和恐龙壳组合的显著变化，反映了受限海洋到边缘海洋环境中的高度动态环境。11/10-1井穿透的卢比阶序列产生了一个新物种，Areoligera？barskii sp.nov.，本文对此进行了详细描述。在所研究的序列中，耐冷水的Svalbardella cooksoniae恐龙囊肿以两个间隔存在。这些间隔与渐新世早期的冷却最大值（Oi-1a和Oi-2事件）有关。此外，这两个间隔与两个局部序列边界相关，表明它们很可能是冰川成因的。根据这些观测结果，我推测早期冰室气候在北海盆地渐新世序列的沉积发展中起着重要作用。尽管始新世-渐新世的过渡期并不完整（即卢特阶至普里亚博阶缺失或浓缩），11/10-1井值得对北海地区早期冰库气候进行高分辨率研究。尽管任何详细的研究理想情况下都应该在传统岩心而不是沟渠岩屑上进行，但该地区不存在跨越始新世-渐新世过渡期的此类样品。
{"title":"Early Oligocene dinocysts as a tool for palaeoenvironment reconstruction and stratigraphical framework – a case study from a North Sea well","authors":"K. Śliwińska","doi":"10.5194/jm-38-143-2019","DOIUrl":"https://doi.org/10.5194/jm-38-143-2019","url":null,"abstract":"Abstract. The lower Oligocene (Rupelian) successions are climate record archives of the early icehouse world in the Cenozoic. Even though the number of studies focussing on the generally cold Oligocene is increasing, little is known about climatic variations in the mid-latitudes to high latitudes of the Northern Hemisphere. One of the major obstacles is the lack of stratigraphically complete uppermost Eocene to Oligocene successions in these regions. This study focusses on dinoflagellate cysts (dinocysts) from a thick nearly complete Rupelian succession in the Syracuse Oils Norge A/S well 11/10-1 drilled in 1969 in the Norwegian part of the North Sea basin. The well provides a record of mid-latitude dinocyst assemblages, which yield key biostratigraphical and palaeoenvironmental information. All the analyses were undertaken on ditch cutting samples. The dinocyst assemblages confirm that the well penetrates about 600 m of Rupelian sediments and (as supported by correlation with the Nini-1 well) that the lowermost Rupelian (below the top or the last occurrence of Areosphaeridium diktyoplokum) is expanded. These assemblages also indicate the presence of two hiatuses: the first extends from the Lutetian to the Priabonian (equivalent to the D9nb–D12nb zones), and the second spans the Rupelian–Chattian boundary (equivalent to the D14nb subzone or the NSO-5 zone). Despite the risk of caving, the dinocyst assemblages support the existing sequence stratigraphic framework. The assemblages reflect a clear transition from distal to proximal deposition in the vicinity of the site (across the regional seismic sequences OSS-1 – OSS meaning Oligocene seismic sequence – to OSS-2). The proximal deltaic deposits of the OSS-2 regressive system tract (RST) are characterised by pulses of high sea-surface productivity and pronounced shifts in the dinocyst assemblages, reflecting a highly dynamic environment in a restricted marine to marginal marine setting. The Rupelian succession penetrated by well 11/10-1 yields one new species, Areoligera? barskii sp. nov., which is described here in detail. The cold-water-tolerant dinocyst Svalbardella cooksoniae is present in two intervals in the studied succession. These intervals are related to the early Oligocene cooling maxima (the Oi-1a and the Oi-2 events). Furthermore, these two intervals correlate with two local sequence boundaries, suggesting that they are most probably of glacioeustatic origin. From these observations, I postulate that the early icehouse climate played an important role in the depositional development of the Oligocene succession in the North Sea basin. Even though the Eocene–Oligocene transition interval is not complete (i.e. Lutetian to Priabonian is either missing or condensed), well 11/10-1 merits high-resolution studies of the early icehouse climate for the North Sea region. Although any detailed studies should ideally be undertaken on conventional cores instead of ditch cuttings, no such samples spa","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45463667","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. The Christian Malford lagerstätte in the Oxford Clay Formation of Wiltshire contains exceptionally well-preserved squid-like cephalopods, including Belemnotheutis antiquus (Pearce). Some of these fossils preserve muscle tissue, contents of ink sacks and other soft parts of the squid, including arms with hooks in situ and the head area with statoliths (ear bones) present in life position. The preservation of soft-tissue material is usually taken as an indication of anoxic or dysaerobic conditions on the sea floor and within the enclosing sediments. Interestingly, in the prepared residues of all these sediments there are both statoliths and arm hooks as well as abundant, species-rich, assemblages of both foraminifera and ostracods. Such occurrences appear to be incompatible with an interpretation of potential sea floor anoxia. The mudstones of the Oxford Clay Formation may have been compacted by 70 %–80 % during de-watering and burial, and in such a fine-grained lithology samples collected for microfossil examination probably represent several thousand years and, therefore, a significant number of foraminiferal life cycles. Such samples (even if only 1–2 cm thick) could, potentially, include several oxic–anoxic cycles and, if coupled with compaction, generate the apparent coincidence of well-preserved, soft-bodied, cephalopods and diverse assemblages of benthic foraminifera.
{"title":"Reconstructing the Christian Malford ecosystem in the Oxford Clay Formation (Callovian, Jurassic) of Wiltshire: exceptional preservation, taphonomy, burial and compaction","authors":"M. Hart, K. Page, G. Price, C. Smart","doi":"10.5194/JM-38-133-2019","DOIUrl":"https://doi.org/10.5194/JM-38-133-2019","url":null,"abstract":"Abstract. The Christian Malford lagerstätte in the Oxford Clay Formation of Wiltshire contains exceptionally well-preserved squid-like cephalopods, including Belemnotheutis antiquus (Pearce). Some of these fossils preserve muscle tissue, contents of ink sacks and other soft parts of the squid, including arms with hooks in situ and the head area with statoliths (ear bones) present in life position. The preservation of soft-tissue material is usually taken as an indication of anoxic or dysaerobic conditions on the sea floor and within the enclosing sediments. Interestingly, in the prepared residues of all these sediments there are both statoliths and arm hooks as well as abundant, species-rich, assemblages of both foraminifera and ostracods. Such occurrences appear to be incompatible with an interpretation of potential sea floor anoxia. The mudstones of the Oxford Clay Formation may have been compacted by 70 %–80 % during de-watering and burial, and in such a fine-grained lithology samples collected for microfossil examination probably represent several thousand years and, therefore, a significant number of foraminiferal life cycles. Such samples (even if only 1–2 cm thick) could, potentially, include several oxic–anoxic cycles and, if coupled with compaction, generate the apparent coincidence of well-preserved, soft-bodied, cephalopods and diverse assemblages of benthic foraminifera.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43998417","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}
A. Rebotim, A. Voelker, L. Jonkers, J. Waniek, M. Schulz, M. Kučera
Abstract. Stable oxygen isotopes (δ18O) of planktonic foraminifera are one of the most used tools to reconstruct environmental conditions of the water column. Since different species live and calcify at different depths in the water column, the δ18O of sedimentary foraminifera reflects to a large degree the vertical habitat and interspecies δ18O differences and can thus potentially provide information on the vertical structure of the water column. However, to fully unlock the potential of foraminifera as recorders of past surface water properties, it is necessary to understand how and under what conditions the environmental signal is incorporated into the calcite shells of individual species. Deep-dwelling species play a particularly important role in this context since their calcification depth reaches below the surface mixed layer. Here we report δ18O measurements made on four deep-dwelling Globorotalia species collected with stratified plankton tows in the eastern North Atlantic. Size and crust effects on the δ18O signal were evaluated showing that a larger size increases the δ18O of G. inflata and G. hirsuta, and a crust effect is reflected in a higher δ18O signal in G. truncatulinoides. The great majority of the δ18O values can be explained without invoking disequilibrium calcification. When interpreted in this way the data imply depth-integrated calcification with progressive addition of calcite with depth to about 300 m for G. inflata and to about 500 m for G. hirsuta. In G. scitula, despite a strong subsurface maximum in abundance, the vertical δ18O profile is flat and appears dominated by a surface layer signal. In G. truncatulinoides, the δ18O profile follows equilibrium for each depth, implying a constant habitat during growth at each depth layer. The δ18O values are more consistent with the predictions of the Shackleton (1974) palaeotemperature equation, except in G. scitula which shows values more consistent with the Kim and O'Neil (1997) prediction. In all cases, we observe a difference between the level where most of the specimens were present and the depth where most of their shell appears to calcify.
{"title":"Calcification depth of deep-dwelling planktonic foraminifera from the eastern North Atlantic constrained by stable oxygen isotope ratios of shells from stratified plankton tows","authors":"A. Rebotim, A. Voelker, L. Jonkers, J. Waniek, M. Schulz, M. Kučera","doi":"10.5194/JM-38-113-2019","DOIUrl":"https://doi.org/10.5194/JM-38-113-2019","url":null,"abstract":"Abstract. Stable oxygen isotopes (δ18O) of planktonic foraminifera are\u0000one of the most used tools to reconstruct environmental conditions of the\u0000water column. Since different species live and calcify at different depths\u0000in the water column, the δ18O of sedimentary foraminifera\u0000reflects to a large degree the vertical habitat and interspecies δ18O differences and can thus potentially provide information on the\u0000vertical structure of the water column. However, to fully unlock the\u0000potential of foraminifera as recorders of past surface water properties, it\u0000is necessary to understand how and under what conditions the environmental\u0000signal is incorporated into the calcite shells of individual species.\u0000Deep-dwelling species play a particularly important role in this context\u0000since their calcification depth reaches below the surface mixed layer. Here\u0000we report δ18O measurements made on four deep-dwelling\u0000Globorotalia species collected with stratified plankton tows in the eastern North\u0000Atlantic. Size and crust effects on the δ18O signal were\u0000evaluated showing that a larger size increases the δ18O of G. inflata and\u0000G. hirsuta, and a crust effect is reflected in a higher δ18O signal in G. truncatulinoides. The great\u0000majority of the δ18O values can be explained without invoking\u0000disequilibrium calcification. When interpreted in this way the data imply\u0000depth-integrated calcification with progressive addition of calcite with\u0000depth to about 300 m for G. inflata and to about 500 m for G. hirsuta. In G. scitula, despite a strong\u0000subsurface maximum in abundance, the vertical δ18O profile is\u0000flat and appears dominated by a surface layer signal. In G. truncatulinoides, the δ18O profile follows equilibrium for each depth, implying a constant\u0000habitat during growth at each depth layer. The δ18O values are\u0000more consistent with the predictions of the Shackleton (1974)\u0000palaeotemperature equation, except in G. scitula which shows values more consistent\u0000with the Kim and O'Neil (1997) prediction. In all cases, we observe a\u0000difference between the level where most of the specimens were present and\u0000the depth where most of their shell appears to calcify.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46496579","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}
Sota Niiyama, G. Tanaka, T. Komatsu, H. D. Doan, H. B. Nguyen, H. T. Trinh, Minh T. Nguyen
Abstract. In this study, we investigated ostracod assemblages from the Co To Islands in northeastern Vietnam. We identified 77 ostracod species belonging to 46 genera in nine surface sediment samples and recognized three biofacies (I, II, and III) based on Q-mode cluster analysis. The dominant species of biofacies I and II were Aurila hataii, Loxoconcha japonica, and Xestoleberis hanaii, which commonly occur in seaweed beds from southern China to Japan. This is the first report on the ostracod assemblage from the open-sea area in northeastern Vietnam. We clarified that the ostracod assemblages in the Gulf of Tongking, including northern Vietnam, have a strong biogeographical relationship with East Asia seas. A new species, Loxoconcha cotoensis sp. nov., was described herein from the Co To Islands (http://www.zoobank.org/NomenclaturalActs/41d3fb9f-ae17-4215-82c1-0874a8bf1a30, last access: 3 June 2019).
{"title":"Holocene ostracod assemblages from the Co To Islands, northeastern Vietnam","authors":"Sota Niiyama, G. Tanaka, T. Komatsu, H. D. Doan, H. B. Nguyen, H. T. Trinh, Minh T. Nguyen","doi":"10.5194/JM-38-97-2019","DOIUrl":"https://doi.org/10.5194/JM-38-97-2019","url":null,"abstract":"Abstract. In this study, we\u0000investigated ostracod assemblages from the Co To Islands in northeastern\u0000Vietnam. We identified 77 ostracod species belonging to 46 genera in nine\u0000surface sediment samples and recognized three biofacies (I, II, and III)\u0000based on Q-mode cluster analysis. The dominant species of biofacies I and II\u0000were Aurila hataii, Loxoconcha japonica, and\u0000Xestoleberis hanaii, which commonly occur in seaweed beds from\u0000southern China to Japan. This is the first report on the ostracod assemblage\u0000from the open-sea area in northeastern Vietnam. We clarified that the\u0000ostracod assemblages in the Gulf of Tongking, including northern Vietnam,\u0000have a strong biogeographical relationship with East Asia seas. A new\u0000species, Loxoconcha cotoensis sp. nov., was described herein from\u0000the Co To Islands\u0000(http://www.zoobank.org/NomenclaturalActs/41d3fb9f-ae17-4215-82c1-0874a8bf1a30, last access: 3 June 2019).\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46174543","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}
P. Jardine, W. Gosling, B. Lomax, Adele C. M. Julier, W. Fraser
Abstract. The grass family (Poaceae) is one of the most economically important plant groups in the world today. In particular many major food crops, including rice, wheat, maize, rye, barley, oats and millet, are grasses that were domesticated from wild progenitors during the Holocene. Archaeological evidence has provided key information on domestication pathways of different grass lineages through time and space. However, the most abundant empirical archive of floral change – the pollen record – has been underused for reconstructing grass domestication patterns because of the challenges of classifying grass pollen grains based on their morphology alone. Here, we test the potential of a novel approach for pollen classification based on the chemical signature of the pollen grains measured using Fourier transform infrared (FTIR) microspectroscopy. We use a dataset of eight domesticated and wild grass species, classified using k-nearest neighbour classification coupled with leave-one-out cross validation. We demonstrate a 95 % classification success rate on training data and an 82 % classification success rate on validation data. This result shows that FTIR spectroscopy can provide enhanced taxonomic resolution enabling species level assignment from pollen. This will enable the full testing of the timing and drivers of domestication and agriculture through the Holocene.
{"title":"Chemotaxonomy of domesticated grasses: a pathway to understanding the origins of agriculture","authors":"P. Jardine, W. Gosling, B. Lomax, Adele C. M. Julier, W. Fraser","doi":"10.5194/JM-38-83-2019","DOIUrl":"https://doi.org/10.5194/JM-38-83-2019","url":null,"abstract":"Abstract. The grass family (Poaceae) is one of the most\u0000economically important plant groups in the world today. In particular many\u0000major food crops, including rice, wheat, maize, rye, barley, oats and\u0000millet, are grasses that were domesticated from wild progenitors during the\u0000Holocene. Archaeological evidence has provided key information on\u0000domestication pathways of different grass lineages through time and space.\u0000However, the most abundant empirical archive of floral change – the pollen\u0000record – has been underused for reconstructing grass domestication\u0000patterns because of the challenges of classifying grass pollen grains based\u0000on their morphology alone. Here, we test the potential of a novel approach\u0000for pollen classification based on the chemical signature of the pollen\u0000grains measured using Fourier transform infrared (FTIR) microspectroscopy.\u0000We use a dataset of eight domesticated and wild grass species, classified\u0000using k-nearest neighbour classification coupled with leave-one-out cross\u0000validation. We demonstrate a 95 % classification success rate on training\u0000data and an 82 % classification success rate on validation data. This\u0000result shows that FTIR spectroscopy can provide enhanced taxonomic\u0000resolution enabling species level assignment from pollen. This will enable\u0000the full testing of the timing and drivers of domestication and agriculture\u0000through the Holocene.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49588398","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. Species of Aulacodiscus and Trinacria, two important marine diatom genera with biostratigraphic utility in offshore North Sea exploration and onshore correlation, are identified, described and emended and the North Sea microfaunal zonation scheme is revised accordingly. Occurring mainly as pyritised diatom moulds or steinkerns, detailed scanning electron microscope (SEM) analysis of several specimens, formerly in open nomenclature, has allowed the correct taxonomic identification of pyritised morphologies found to belong to the genus Aulacodiscus, including A. allorgei, A. heterostictus, A. insignis, A. singilewskyanus, A. subexcavatus and A. suspectus. The important marker species Trinacria regina is emended. SEM studies, using specimens preserved in pyrite and original silica, have shed further light on the varying forms and frustule morphology of Trinacria regina so that valves and frustules formerly thought to represent separate species are now found to be grouped within this taxon; SEM studies have shown that many of these variations represent different valves within a chain, whilst others may signify ecophenotypic variants. Emendments are therefore made to clarify the taxonomic status of different variants within T. regina, important in the Palaeocene–Eocene boundary interval onshore and offshore such as the Sele and Balder formations and the Fur Formation diatomite of Jutland, Denmark. Species of taxa formerly in open nomenclature are now assigned to Aulacodiscus insignis, which are important offshore markers in offshore late Oligocene to early Miocene sediments in northwest Europe.
摘要本文对Aulacodiscus和Trinacria这两个重要的海洋硅藻属进行了鉴定、描述和修正，并对北海微区系划分方案进行了相应的修订。主要以黄铁矿化硅藻霉菌或steinkerns的形式出现，对几个标本进行了详细的扫描电镜(SEM)分析，发现黄铁矿化形态属于Aulacodiscus属，包括A. alloorgei, A. heterostictus, A. insignis, A. singilewskyanus, A. subbexcavatus和A. susectus。对重要的标志种金银花进行了订正。利用保存在黄铁矿和原始二氧化硅中的标本进行的扫描电镜研究，进一步揭示了tracria regina的不同形态和截果形态，因此，以前被认为代表不同物种的阀和截果现在被发现归在这个分类单元中;扫描电镜研究表明，许多这些变异代表了链中的不同阀门，而其他变异可能意味着生态表型变异。因此，对T. regina中不同变体的分类地位进行了修正，T. regina在古新世-始新世边界段的陆上和海上都很重要，如丹麦日德兰半岛的Sele和Balder组以及Fur组硅藻土。在欧洲西北部晚渐新世至早中新世的近海沉积物中，原属开放命名的分类群种被划归为Aulacodiscus insignis。
{"title":"Species of the diatom taxa Aulacodiscus and Trinacria with biostratigraphic utility in Palaeogene and Neogene North Sea sediments","authors":"A. Mitlehner","doi":"10.5194/JM-38-67-2019","DOIUrl":"https://doi.org/10.5194/JM-38-67-2019","url":null,"abstract":"Abstract. Species of Aulacodiscus and Trinacria, two important marine diatom genera with biostratigraphic utility in offshore North Sea exploration and onshore correlation, are identified, described and emended and the North Sea microfaunal zonation scheme is revised accordingly. Occurring mainly as pyritised diatom moulds or steinkerns, detailed scanning electron microscope (SEM) analysis of several specimens, formerly in open nomenclature, has allowed the correct taxonomic identification of pyritised morphologies found to belong to the genus Aulacodiscus, including A. allorgei, A. heterostictus, A. insignis, A. singilewskyanus, A. subexcavatus and A. suspectus. The important marker species Trinacria regina is emended. SEM studies, using specimens preserved in pyrite and original silica, have shed further light on the varying forms and frustule morphology of Trinacria regina so that valves and frustules formerly thought to represent separate species are now found to be grouped within this taxon; SEM studies have shown that many of these variations represent different valves within a chain, whilst others may signify ecophenotypic variants. Emendments are therefore made to clarify the taxonomic status of different variants within T. regina, important in the Palaeocene–Eocene boundary interval onshore and offshore such as the Sele and Balder formations and the Fur Formation diatomite of Jutland, Denmark. Species of taxa formerly in open nomenclature are now assigned to Aulacodiscus insignis, which are important offshore markers in offshore late Oligocene to early Miocene sediments in northwest Europe.","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44661531","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. The morphology of dinoflagellate cysts (dinocysts) is related not only to the genetics of the motile dinoflagellate from which it derives, but is also dependent on a range of environmental factors including salinity, temperature and nutrient status. Although this knowledge improves our understanding of the drivers behind dinocyst morphological variations, it makes the taxonomy governing their description somewhat complex. In basins such as the Black Sea, where environmental change can be extreme and occurs on relatively short (millennial) timescales, taxonomy becomes particularly challenging. Morphological continua can be observed between described forms, displaying a large range of intermediate phenotypes that do not necessarily correspond to any genetic difference. As these morphological nuances may preserve information about palaeoenvironments, it is important to find a systematic method of characterising morphotypes. Here, we show a dinocyst matrix within which dinocysts are described according to their similarity to (or difference from) described forms based on key descriptive parameters. In the example set out here, cyst shape and degree of process and/or ectophragm development are taken as two key parameters in Pyxidinopsis psilata and Spiniferites cruciformis, and can allow the description of intermediate forms even though the definitions do not overlap. We review some frequently occurring morphotypes and propose that using matrices to show the gradual variation between endmember forms is the most pragmatic approach until cyst–theca studies and genetic sequencing can be used to demonstrate relationships between genotypes and morphotypes. As prior studies propose salinity to be a primary driver of intraspecific variability, the endmembers presented may represent salinity extremes within an overall brackish environment. Although we cannot assign each morphotype to a value or a range of an environmental parameter (e.g. salinity) as the different morphotypes can occur in the same sample, using this matrix allows preservation of information about morphological variability without creating taxonomic categories that are likely to require alteration if genetic evidence becomes available.
{"title":"Where should we draw the lines between dinocyst “species”? Morphological continua in Black Sea dinocysts","authors":"T. M. Hoyle, Manuel Sala-Pérez, F. Sangiorgi","doi":"10.5194/JM-38-55-2019","DOIUrl":"https://doi.org/10.5194/JM-38-55-2019","url":null,"abstract":"Abstract. The morphology of dinoflagellate cysts (dinocysts) is related not only to the\u0000genetics of the motile dinoflagellate from which it derives, but is also\u0000dependent on a range of environmental factors including salinity, temperature\u0000and nutrient status. Although this knowledge improves our understanding of\u0000the drivers behind dinocyst morphological variations, it makes the taxonomy\u0000governing their description somewhat complex. In basins such as the Black\u0000Sea, where environmental change can be extreme and occurs on relatively short\u0000(millennial) timescales, taxonomy becomes particularly challenging.\u0000Morphological continua can be observed between described forms, displaying a\u0000large range of intermediate phenotypes that do not necessarily correspond to\u0000any genetic difference. As these morphological nuances may preserve\u0000information about palaeoenvironments, it is important to find a systematic\u0000method of characterising morphotypes. Here, we show a dinocyst matrix within\u0000which dinocysts are described according to their similarity to (or difference\u0000from) described forms based on key descriptive parameters. In the example set\u0000out here, cyst shape and degree of process and/or ectophragm\u0000development are taken as two key parameters in Pyxidinopsis psilata and Spiniferites cruciformis, and can allow the description of\u0000intermediate forms even though the definitions do not overlap. We review some frequently occurring morphotypes and propose that using\u0000matrices to show the gradual variation between endmember forms is the most\u0000pragmatic approach until cyst–theca studies and genetic sequencing can be\u0000used to demonstrate relationships between genotypes and morphotypes. As prior\u0000studies propose salinity to be a primary driver of intraspecific variability,\u0000the endmembers presented may represent salinity extremes within an overall\u0000brackish environment. Although we cannot assign each morphotype to a value or\u0000a range of an environmental parameter (e.g. salinity) as the different\u0000morphotypes can occur in the same sample, using this matrix allows\u0000preservation of information about morphological variability without creating\u0000taxonomic categories that are likely to require alteration if genetic\u0000evidence becomes available.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42684094","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. This study presents the first detailed calcareous nannofossil assemblage data from the Late Cretaceous succession of the subsurface Aruma Basin, north Oman. The taxonomic description and documentation of assemblage composition are based on extensive quantitative analysis of ditch cuttings and side-wall samples from eight hydrocarbon exploration wells across north Oman. The samples studied from those wells cover the Coniacian to earliest Maastrichtian deep marine shales and marls of the subsurface Fiqa Formation. These fine-grained siliciclastic deposits often yield moderately to well-preserved nannofossil assemblages, especially in the Campanian intervals. Consequently, diverse assemblages have been recorded from the Fiqa Formation, with a total diversity of ∼200 species, including two new species, Staurolithites ormae sp. nov. and Chiastozygus fahudensis sp. nov., which are illustrated and described. Extensive imaging of this diversity is provided here, as are stratigraphic distributions of the main components from a key reference well in north Oman, W-4. Poorly described groups such as Staurolithites are closely investigated and their utility for stratigraphic applications is highlighted. Relative abundances of nannofossil taxa with strong palaeoenvironmental preferences have revealed new insights into the palaeo-productivity of the basin. High-fertility species like Discorhabdus ignotus, Biscutum constans and Zeugrhabdotus erectus show substantial variations in abundance throughout the Fiqa Formation, reflecting long-term shifts in the productivity conditions of the basin. This is supported by abundance patterns of Watznaueria barnesiae and Micula staurophora that show a broadly inverse correlation with the high-fertility species. The Fiqa Formation represents a key regional seal unit for the Cretaceous hydrocarbon reservoirs of Oman, as well as being a productive unit elsewhere in the Arabian Peninsula. Beyond the Aruma Basin of Oman, this study will provide a key reference point for future biostratigraphic or palaeoenvironmental analyses of the Late Cretaceous calcareous nannofossil assemblages across the Middle East and other southern Tethyan areas.
{"title":"Calcareous nannofossil assemblages of the Late Cretaceous Fiqa Formation, north Oman","authors":"Zainab Al Rawahi, T. Dunkley Jones","doi":"10.5194/JM-38-25-2019","DOIUrl":"https://doi.org/10.5194/JM-38-25-2019","url":null,"abstract":"Abstract. This study presents the\u0000first detailed calcareous nannofossil assemblage data from the Late\u0000Cretaceous succession of the subsurface Aruma Basin, north Oman. The\u0000taxonomic description and documentation of assemblage composition are based\u0000on extensive quantitative analysis of ditch cuttings and side-wall samples\u0000from eight hydrocarbon exploration wells across north Oman. The samples\u0000studied from those wells cover the Coniacian to earliest Maastrichtian deep\u0000marine shales and marls of the subsurface Fiqa Formation. These fine-grained\u0000siliciclastic deposits often yield moderately to well-preserved nannofossil\u0000assemblages, especially in the Campanian intervals. Consequently, diverse\u0000assemblages have been recorded from the Fiqa Formation, with a total\u0000diversity of ∼200 species, including two new species,\u0000Staurolithites ormae sp. nov. and Chiastozygus fahudensis\u0000sp. nov., which are illustrated and described. Extensive imaging of this\u0000diversity is provided here, as are stratigraphic distributions of the main\u0000components from a key reference well in north Oman, W-4. Poorly described\u0000groups such as Staurolithites are closely investigated and their\u0000utility for stratigraphic applications is highlighted. Relative abundances of\u0000nannofossil taxa with strong palaeoenvironmental preferences have revealed\u0000new insights into the palaeo-productivity of the basin. High-fertility\u0000species like Discorhabdus ignotus, Biscutum constans and\u0000Zeugrhabdotus erectus show substantial variations in abundance\u0000throughout the Fiqa Formation, reflecting long-term shifts in the\u0000productivity conditions of the basin. This is supported by abundance patterns\u0000of Watznaueria barnesiae and Micula staurophora that show a\u0000broadly inverse correlation with the high-fertility species. The Fiqa\u0000Formation represents a key regional seal unit for the Cretaceous hydrocarbon\u0000reservoirs of Oman, as well as being a productive unit elsewhere in the\u0000Arabian Peninsula. Beyond the Aruma Basin of Oman, this study will provide a\u0000key reference point for future biostratigraphic or palaeoenvironmental\u0000analyses of the Late Cretaceous calcareous nannofossil assemblages across the\u0000Middle East and other southern Tethyan areas.\u0000","PeriodicalId":54786,"journal":{"name":"Journal of Micropalaeontology","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2019-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47844822","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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