Marine Micropaleontology最新文献_第2页

Modern benthic foraminifera distribution in littoral environments of Bahía Samborombón Bahía Samborombón沿海环境中的现代底栖有孔虫分布

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-10-21 DOI: 10.1016/j.marmicro.2025.102524

Angélica Ballesteros-Prada , Emiliana Bernasconi , Isabel Vilanova , Mariel Luengo , Enrique Fucks

Foraminiferal assemblages of littoral and coastal environment have been widely used in modern analog studies to interpret the effects of past warm periods, such as those during the Quaternary, on shoreline dynamics and relative sea-level changes. This study analyzes benthic foraminiferal assemblages in four sectors of Bahía Samborombón (R36, RS, C15, and PR), to characterize depositional environments and describe the composition and distribution of benthic foraminiferal assemblage. The comparison between living and total foraminiferal assemblages in Bahía Samborombón reveals that living faunas reflect short-term local conditions, whereas total assemblages provide a more diverse, time-averaged record influenced by depositional and preservational processes. Six species associations characteristic of different marginal-marine depositional environments were identified. Association A, dominated by Cribroelphidium spp., was associated with low salinity, high energy, and a high sand content. Association B, was represented by Trochammina inflata and Jadammina polystoma, typical of mid-marsh environments. Association C, dominated by Astrononion sp.1 and Arenoparella mexicana, was linked to low-salinity tidal channels. Association D, dominated by Jadammina polystoma and Miliammina fusca, represents high marshes. Association E, under greater marine influence, was dominated by Buccella peruviana and Quinqueloculina spp., while association F, dominated by Ammonia parkinsoniana, was related with low marshes to intertidal zones. The results suggest that benthic foraminiferal assemblages primarily respond to variations in conductivity, but they are also influenced by other physicochemical and oceanographic factors, such as tidal regimes, as well as by taphonomic and ecological processes that influencing their distribution and preservation in these marginal-marine environments.

在现代模拟研究中，有孔虫组合被广泛用于解释过去暖期（如第四纪暖期）对海岸线动态和相对海平面变化的影响。本文分析了Bahía Samborombón 4个扇区（R36、RS、C15和PR）的底栖有孔虫组合，以表征沉积环境，描述底栖有孔虫组合的组成和分布。Bahía Samborombón中活的和总有孔虫组合的比较表明，活的动物群反映了短期的当地条件，而总组合提供了一个更多样化的、受沉积和保存过程影响的时间平均记录。确定了6种不同边缘-海相沉积环境的物种组合特征。群落A以Cribroelphidium spp为主，具有低盐度、高能量和高含沙量的特征。类群B以膨体Trochammina inflata和多口Jadammina polystoma为代表，典型的中沼泽环境。群落C主要由Astrononion sp.1和arenoppararella mexicana组成，与低盐度潮汐通道有关。丛D以水杨多口草和水杨多口草为主，代表高沼泽。群落E受海洋影响较大，以秘鲁布氏菌（Buccella peruviana）和Quinqueloculina属为主，群落F以氨帕金森菌（氨帕金森菌）为主，与低沼泽到潮间带有关。结果表明，底栖有孔虫组合主要响应电导率的变化，但它们也受到其他物理化学和海洋学因素的影响，如潮汐制度，以及影响它们在这些边缘海洋环境中分布和保存的地学和生态过程。

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引用次数: 0

A 9000-year marine diatom assemblage reconstruction off Eastern Tasmania, Australia, using microfossil and molecular methods 利用微化石和分子方法重建澳大利亚东塔斯马尼亚海域9000年的海洋硅藻组合

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-10-10 DOI: 10.1016/j.marmicro.2025.102520

Bradley Paine , Linda Armbrecht , Christopher Bolch , Gustaaf M. Hallegraeff

Over the past fifty years, Eastern Tasmanian waters have experienced rapid warming, primarily due to the extension of the East Australian Current. This has driven expansion of warm-water biota and decline of those adapted to cooler conditions, including phytoplankton. Presently, plankton monitoring, including diatoms along Eastern Tasmania, spans <100 years. This study reconstructed diatom communities throughout a sediment core spanning 9000 years before present (9 kyrs BP), using microfossil analysis and molecular techniques, including sedimentary ancient DNA (sedaDNA) and 18S rRNA from a 10-year water column archive at the Maria Island IMOS National Reference Station mooring.

Microfossil analysis revealed a dominance of strongly silicified benthic taxa (Campylodiscus, Diploneis, Paralia, Pyxidicula, Triceratium). Notably, Paralia sulcata showed a shift ∼6 kyrs BP from small to larger cells, possibly reflecting a transition from a coastal to shelf ecosystem. However, microfossils underrepresented lightly silicified planktonic diatoms. Molecular methods detected higher diatom diversity, though up to 50 % of sedaDNA reads remained unclassified due to reference library limitations. Lightly silicified planktonic genera (Chaetoceros, Corethron, Lithodesmium, Rhizosolenia) were identified only via molecular approaches and comprised 73 % of sedaDNA and 88 % of 18S rRNA records. Of 10 shared diatom families, 5, 15, and 4 were unique to microscopy, sedaDNA, and 18S rRNA, respectively. SedaDNA also captured greater benthic diversity.

Our findings revealed limitations in reconstructing historic diatom assemblages from sediment cores. Microfossils faced constraints due to difficulties in morphological identification and preservation biases. In contrast, sedaDNA analysis yielded finer taxonomic resolution, provided access to high-quality reference sequence libraries were available.

在过去的50年里，东塔斯马尼亚水域经历了快速变暖，主要是由于东澳大利亚洋流的延伸。这导致了温水生物群的扩张和适应较冷环境的生物群的减少，包括浮游植物。目前，浮游生物监测，包括东塔斯马尼亚岛的硅藻，跨越了100年。本研究利用微化石分析和分子技术，包括从Maria Island IMOS国家参考站系泊的10年水柱档案中提取的沉积古DNA （sedaDNA）和18S rRNA，重建了距今9000年（9 kyrs BP）的沉积物岩心中的硅藻群落。微化石分析显示，强硅化底栖动物类群（Campylodiscus, Diploneis, Paralia, Pyxidicula, Triceratium）占主导地位。值得注意的是，Paralia sulcata显示出从小细胞到大细胞的转变约6 kyrs BP，可能反映了从沿海到陆架生态系统的转变。然而，微化石不足以代表轻硅化浮游硅藻。分子方法检测到更高的硅藻多样性，尽管由于参考文库的限制，高达50%的sedaDNA读数仍未分类。轻硅化浮游生物属（Chaetoceros, Corethron, Lithodesmium, rhizzosolenia）仅通过分子方法鉴定，占sedaDNA记录的73%和18S rRNA记录的88%。在共有的10个硅藻家族中，5个、15个和4个分别是显微镜、sedaDNA和18S rRNA所特有的。SedaDNA还捕获了更多的底栖生物多样性。我们的发现揭示了从沉积物岩心重建历史硅藻组合的局限性。微化石由于形态鉴定困难和保存偏差而受到限制。相比之下，如果能够获得高质量的参考序列库，sedaDNA分析可以获得更精细的分类分辨率。

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引用次数: 0

Calcareous nannofossil biostratigraphy of the upper cretaceous to lower Paleocene succession in the Zagros Basin, western Iran: Implications for the OAE2 and PETM events 伊朗西部Zagros盆地上白垩统至下古新统演替的钙质纳米化石生物地层学：对OAE2和PETM事件的启示

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-10-08 DOI: 10.1016/j.marmicro.2025.102522

Shokoufeh Mori , Sakineh Arefifard , Thomas J. Algeo , Jonathan D. Schueth

Upper Cretaceous and Paleogene deposits are broadly distributed within the Zagros Basin of western and southwestern Iran, yet a nearly continuous stratigraphic record of the calcareous nannofossil stratigraphy of this region has not been generated to date. Rich and diverse assemblages of calcareous nannofossil are present in the uppermost Cenomanian to Ypresian deposits of the Arkavaz section on the southwestern limb of the Kabir Kuh Anticline. The presence of the taxon Marthasterites furcatus demonstrates a late Turonian age for the base of the section. Two hiatuses were identified: one at the Santonian/Campanian boundary, where the UC13 Biozone is missing, and the other in the lower Campanian, where the UC15a-b Biozone is missing. The bulk of the section is of Campanian age, indicating a high sedimentation rate during that stage. The Cretaceous/Paleogene boundary is marked by abundant calcareous dinoflagellates as well as increased abundances of calcispheres (“Thoracosphaera” sp.) and Neobiscutum. A complete record of key index taxa of Paleocene to lower Eocene biozones NP1–12 is present. We note elevated abundance of Biscutum constans, Discorhabdus ignotus, and Zeugrhabdotus noeliae coeval with the Cenomanian/Turonian boundary (CTB) respectively, similar to records in other Tethyan sections. The PETM interval contains abundant oligotrophic taxa such as Sphenolithus and Zygrhablithus but lacks many of the nannofossil taxa noted elsewhere, whereas other PETM sections in the Tethyan region are characterized by a notable decrease in oligotrophic taxa. The Arkavaz section is a leading target for further study of paleoenvironmental changes and biotic events through the Late Cretaceous to Paleogene.

上白垩统和古近系沉积广泛分布于伊朗西部和西南部的扎格罗斯盆地，但该地区的钙质纳米化石地层学至今尚未形成近乎连续的地层记录。在Kabir Kuh背斜西南翼Arkavaz剖面的最上层Cenomanian - Ypresian矿床中存在丰富多样的钙质纳米化石组合。马萨斯特石分叉区分类群的存在表明该剖面的基底属于晚Turonian时代。发现了两个断裂带：一个位于圣东-坎帕纪边界，缺少UC13生物带；另一个位于下坎帕纪，缺少UC15a-b生物带。该剖面大部分为坎帕期，表明该时期沉积速率较高。白垩纪与古近纪的界线以丰富的钙质鞭毛藻为标志，同时钙质鞭毛藻（“胸osphaera”sp.）和Neobiscutum的丰度也有所增加。完整记录了古新世至始新世下生物带NP1-12的关键指标类群。我们注意到，与Cenomanian/Turonian边界（CTB）同期，分别有大量的constans、Discorhabdus ignotus和Zeugrhabdotus noeliae，与其他特提斯剖面的记录相似。在Tethyan地区的其他PETM剖面中，少营养类群明显减少，但在Sphenolithus和Zygrhablithus等少营养类群中却缺少许多纳米化石类群。Arkavaz剖面是进一步研究晚白垩世至古近纪古环境变化和生物事件的主要目标。

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引用次数: 0

Biostratigraphy and petrography of Miocene sediments in the southeastern Nam Con Son Basin, Vietnam 越南南con Son盆地东南部中新世沉积物的生物地层学和岩石学

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-10-03 DOI: 10.1016/j.marmicro.2025.102521

Nguyen Van Su, Nguyen Tan Trieu, Mai Hoang Dam, Nguyen Thi Tham, Bui Thi Ngoc Phuong

This study integrates biostratigraphic and petrographic data from five wells to characterize Miocene sediments in the southeastern Nam Con Son Basin, offshore Vietnam. The Miocene succession is divided into three distinct units. The Lower Miocene (foraminiferal zones M1b–M5, nannofossil zones CNM2–CNM6) consists of sandstone, siltstone, and calcareous claystone deposited in intertidal to middle neritic environments, characterized by low microfossil abundance. The overlying Middle Miocene (M5–M9, CNM7–CNM9) comprises sandstone interbedded with packstone and wackestone and records a significant increase in microfossil abundance and diversity, indicating a transgression into middle to outer neritic settings. A major stratigraphic hiatus, marked by the absence of zones M10–M13a and CNM10–CNM14, separates the Middle from the Upper Miocene. The latter unit (M13b–M14, CNM15–CNM20) is composed of limestone, calcareous claystone, and siliciclastic sediments and exhibits a peak in microfossil abundance and diversity, reflecting continued deepening to outer neritic and upper bathyal conditions. Reservoir quality varies significantly across the succession. While the Lower and Middle Miocene sandstones and Upper Miocene limestones exhibit moderate to good porosity enhanced by grain dissolution, the Lower and Middle Miocene limestones show poor porosity due to cementation. This refined stratigraphic framework significantly improves regional correlation and enhances geological models for future hydrocarbon exploration in the basin.

本研究综合了5口井的生物地层和岩石学资料，对越南近海南con Son盆地东南部中新世沉积物进行了表征。中新世的演替分为三个不同的单元。下中新世（有孔虫带M1b-M5，纳米化石带CNM2-CNM6）由沉积于潮间带至中浅海环境的砂岩、粉砂岩和钙质粘土岩组成，微化石丰度较低。上覆的中中新世（M5-M9, CNM7-CNM9）为砂岩与复盖岩和碎屑岩互层，微化石丰度和多样性显著增加，表明其向中-外浅海环境海侵。以M10-M13a带和CNM10-CNM14带的缺失为标志的主要地层间隙将中中新世与上中新世分隔开来。后一单元（M13b-M14, CNM15-CNM20）由灰岩、钙质粘土岩和硅质碎屑沉积物组成，微化石丰度和多样性达到峰值，反映了向外浅海和上深海环境的持续深化。不同演替层的储层质量差异显著。中新世下、中砂岩和中新世上灰岩在颗粒溶蚀作用下表现出中等至良好的孔隙度，中新世下、中灰岩在胶结作用下表现出较差的孔隙度。这种精细的地层格架大大提高了区域对比，为今后盆地油气勘探提供了地质模型。

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引用次数: 0

Deep learning object detection for fossil diatom counting: assessing the impact of fossil preservation and intraspecific morphological variation 化石硅藻计数的深度学习目标检测：评估化石保存和种内形态变化的影响

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-09-26 DOI: 10.1016/j.marmicro.2025.102519

Saki Ishino , Takuya Itaki , Motohisa Fukuda

Recent evidence suggests that object detection techniques based on deep learning are evidently useful for automating microfossil analysis, particularly by enabling the rapid and accurate extraction of target particles. While the assemblage and morphometric analysis of fossil diatoms requires unique procedures, such as including fragmented specimens in counts and accounting for intra-morphometric variation, little is known regarding how these factors affect detection accuracy or how to efficiently construct training datasets for data-driven methods such as deep learning. In this study, we experimentally evaluated the use of the YOLOv5 object detection model to detect Eucampia antarctica, a key paleoenvironmental indicator, across sites in the Southern Ocean that vary in sedimentological and biogeographical characteristics. Detection accuracy was assessed using the datasets from fourteen test sites for the models trained on datasets from four individual sites, that vary within E. antarctica morphology and fossil preservation state, as well as models trained on pairwise combinations of these sites. Our results show that morphological variation of E. antarctica did not significantly affect detection performance, but models trained on datasets of moderately preserved fossils slightly outperformed those trained on datasets of well-preserved fossils. Furthermore, the findings suggest that incorporating diverse non-target particles including other diatom fragments and sediment particles in training data is critical for developing robust models that maintain consistently high performance in diverse regions. Our experiments demonstrate that object detection models allow rapid and accurate counting of E. antarctica, thereby improving its use in paleoenvironmental reconstructions, including past sea ice and surface temperatures.

最近的证据表明，基于深度学习的目标检测技术对于自动化微化石分析显然是有用的，特别是能够快速准确地提取目标颗粒。虽然硅藻化石的组装和形态计量学分析需要独特的程序，例如在计数中包括碎片标本和计算形态计量学内部变化，但关于这些因素如何影响检测准确性或如何有效地构建数据驱动方法（如深度学习）的训练数据集，人们知之甚少。在这项研究中，我们通过实验评估了YOLOv5目标检测模型在南大洋沉积学和生物地理特征不同的地点检测南极洲尤坎皮（eucamia antarctica）这一关键的古环境指标。使用来自14个试验点的数据集对模型的检测精度进行了评估，这些模型是在来自四个单独的试验点的数据集上训练的，这些试验点在南极洲东部的形态和化石保存状态各不相同，以及在这些试验点的成对组合上训练的模型。我们的研究结果表明，南极南极龙的形态变化对检测性能没有显著影响，但在保存较好的化石数据集上训练的模型略优于在保存较好的化石数据集上训练的模型。此外，研究结果表明，在训练数据中加入不同的非目标颗粒，包括其他硅藻碎片和沉积物颗粒，对于开发在不同地区保持一致高性能的鲁棒模型至关重要。我们的实验表明，目标检测模型可以快速准确地计数南极南极冰盖，从而提高其在古环境重建中的应用，包括过去的海冰和表面温度。

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引用次数: 0

Insights into the spatial and vertical distribution of extant planktonic foraminifera in the Bay of Bengal 孟加拉湾现存浮游有孔虫的空间和垂直分布

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-09-25 DOI: 10.1016/j.marmicro.2025.102518

Rose Manceau , Meryem Mojtahid , Eelco Rohling , Robin Fentimen , Thibault de Garidel-Thoron , Sonia Chaabane , Gianluca Marino

Planktonic foraminifera provide essential palaeoceanographic proxies, as their shells are used to characterise past ocean conditions. The accurate interpretation of palaeorecords depends on a thorough understanding of the species-specific ecological preferences. While global distribution patterns are well documented, regional analysis are sparser, which limits our understanding of the response of planktonic foraminiferal distribution to local environmental conditions. This study synthesises data of extant planktonic foraminiferal abundances to determine their spatial and vertical distributions in the Bay of Bengal, using available and published plankton net and sediment trap data. Our analysis highlights the dominance of six species that exhibit distinctive spatial and vertical distribution patterns. Globigerinoides ruber and Trilobatus sacculifer are associated with oligotrophic waters, and nutrient-rich areas, respectively. They consistently inhabit the upper 40 m of the water column, within the mixed layer. Neogloboquadrina dutertrei and Globigerina bulloides thrive in stratified waters near the Ganges-Brahmaputra River mouth and in the upwelling system south of India. While abundant in the mixed layer, their high numbers in the subsurface in stratified conditions and associated subsurface nutrient availability highlights their capacity to dwell in both surface and subsurface environments. Globorotalia cultrata and Globigerinita glutinata are abundant in the northern Bay of Bengal, with G. cultrata inhabiting the upper thermocline, while G. glutinata has the broadest vertical distribution, from the mixed layer to the deep thermocline. These findings help constraining the regional response of key species to local conditions and hence their use in palaeoenvironmental reconstructions from this critical sector of the global ocean.

浮游有孔虫提供了重要的古海洋学代用物，因为它们的壳被用来表征过去的海洋状况。对古记录的准确解释取决于对物种特有的生态偏好的透彻理解。虽然全球分布模式有很好的记录，但区域分析较少，这限制了我们对浮游有孔虫分布对当地环境条件的响应的理解。本研究综合了现有浮游有孔虫丰度的数据，利用现有的和已发表的浮游生物网和沉积物陷阱数据，确定了它们在孟加拉湾的空间和垂直分布。我们的分析强调了6个物种的优势，它们表现出独特的空间和垂直分布模式。gloigerinoides rubber和Trilobatus sacullifer分别与低营养水域和富营养区有关。它们一直栖息在水柱上方40米的混合层内。Neogloboquadrina dutrei和Globigerina bulloides在恒河-布拉马普特拉河口附近的分层水域和印度南部的上升流系统中茁壮成长。虽然在混合层中丰富，但在分层条件下，它们在地下的高数量和相关的地下养分可用性突出了它们在地表和地下环境中的生存能力。在孟加拉湾北部分布有丰富的Globorotalia cultrata和Globigerinita glutinata，其中Globorotalia cultrata分布在温跃层上部，而g.g glutinata垂直分布最广，从混合层到深层温跃层。这些发现有助于限制关键物种对当地条件的区域反应，从而将其用于全球海洋这一关键区域的古环境重建。

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引用次数: 0

Vertical partitioning of siliceous plankton in the stratified waters around Japan 日本周围分层水域硅质浮游生物的垂直分布

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-09-19 DOI: 10.1016/j.marmicro.2025.102517

Yoshiyuki Ishitani , Kozo Takahashi

Vertical distributions of siliceous plankton groups in the seas off Japan were studied to clarify their ecological preferences. Radiolarian standing stock maxima were absent in the layers where silicoflagellate and diatom standing stock maxima occured. The vertical distribution patterns of silicoflagellate species were consistent vertically, whereas their geographic distributions differed, likely reflecting current systems. Two silicoflagellate taxa (Octactis speculum and O. octanaria var. pulchra) showed strong correlations with temperature. In contrast, diatoms displayed two distinct vertical distribution types: Group 1 (above pycnocline) and Group 2 (below pycnocline). Based on their vertical and geographic distributions, large diatoms such as Stephanopyxis palmeriana, Coscinodiscus asteromphalus, C. wailesii group, C. oculus-iridis, C. perforatus, and Stellarima stellaris are identified as a”shade flora“. Members of the family Rhizosoleniaceae exhibit an effective strategy for adapting to oligotrophic conditions. Several taxa can serve as environmental proxies: Thalassiosira eccentrica as nitrate concentration in the surface, Bacteriastrum delicatulum as low temperature and high phosphate, and Phaeoceros spp. and Hyalochaete spp. as nitrite and ammonium stocks. Comparison among siliceous plankton suggests that increasing stratification leads to vertical partitioning among siliceous plankton. Under weak stratification, silicoflagellates and diatoms dominate surface waters, whereas stronger stratification causes silicoflagellates and large centric diatoms to accumulate near the pycnocline, followed by other diatoms. Living radiolarian standing stocks are regulated by siliceous phytoplankton and peak below their abundant layers. This study demonstrates clear vertical partitioning among siliceous plankton groups.

研究了日本海域硅质浮游生物群的垂直分布，以阐明它们的生态偏好。在硅鞭毛虫和硅藻生物量最大值出现的层中，放射虫生物量最大值不存在。垂直分布格局基本一致，但地理分布存在差异，可能反映了当前生态系统的变化。两个硅鞭毛虫类群（Octactis speculum和o.octanaria var. pulchra）与温度有较强的相关性。相反，硅藻呈两种明显的垂直分布类型：第1组（斜斜上方）和第2组（斜斜下方）。根据其垂直和地理分布，大型硅藻如Stephanopyxis palmeriana、Coscinodiscus asteromphalus、C. wailesii群、C. oculus- irridis、C. perforatus和Stellarima stellaris被确定为“遮荫植物群”。根螺线根科的成员表现出一种适应少营养条件的有效策略。可作为环境代用物的分类群有：盐硅藻（thalassisira eccentrica）代表地表硝酸盐浓度，纤弱杆菌（Bacteriastrum delicatulum）代表低温高磷酸盐，褐藻（Phaeoceros spp.）和透明毛藻（Hyalochaete spp.）代表亚硝酸盐和铵储存库。硅质浮游生物之间的比较表明，分层的增加导致了硅质浮游生物之间的垂直分配。在弱分层条件下，硅藻和硅藻在表层水体中占主导地位，而在强分层条件下，硅藻和大中心硅藻在背斜附近聚集，其他硅藻次之。活放射虫存量受硅质浮游植物调控，并在其丰富层以下达到峰值。这项研究表明硅质浮游生物群之间有明显的垂直划分。

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引用次数: 0

Equatorial sea surface temperature and upwelling: A comparative analysis of late quaternary planktonic foraminiferal ecostratigraphy 赤道海面温度与上升流：晚第四纪浮游有孔虫生态地层学的比较分析

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-09-16 DOI: 10.1016/j.marmicro.2025.102516

Lai Shan Sum

Our understanding of Quaternary planktonic foraminiferal ecostratigraphy in the Demerara Rise region is limited. Analysing planktonic foraminiferal assemblage turnovers can help in understanding the palaeoecological changes experienced in this area. A comparison of the planktonic foraminiferal assemblage turnover index (ATI) between tropical cores (ODP Hole 1261A, Demerara Rise; and three En20 piston cores, Leeward Islands) and a subtropical core (ODP Hole 994C, Blake Ridge Plateau) reveals lower mean ATI_s values in the tropics than that in the subtropics. Peaks in ATI_s at ODP Hole 1261A did not coincide with the onset of interglacial periods as they did at ODP Hole 994C, limiting its use for broad correlations. Significant difference in medians of ATI_s values between these cores is attributed to differential heating across latitudes, warm-water species contributing most to the tropical turnovers and dominating the interpretable principal component loadings.

Significant correlation in Globigerina bulloides and Globigerinita glutinata indicate that upwelling contributed to some peak assemblage turnovers. Conversely, there being no significant correlation between Globigerinoides ruber_pink and Neogloboquadrina dutertrei, suggests that the nearby Amazon River did not greatly affect assemblage turnover at the Demerara Rise as much as the equatorial location of the cores and upwelling. Additionally, sequential changes in proportional abundances of the planktonic foraminiferal species indicated variations in upwelling, thermocline depth and sea-levels during glacial terminations. This study demonstrates that the use of ATI highlights multiple factors affecting individual planktonic foraminiferal species and overall assemblages. However, understanding of regional factors is crucial for effectively using ATI as an ecostratigraphic tool.

我们对德默拉拉隆起地区第四纪浮游有孔虫生态地层学的认识有限。分析浮游有孔虫组合更替有助于了解该地区经历的古生态变化。热带岩芯（Demerara Rise的ODP 1261A孔和背风群岛的三个En20活塞岩芯）和亚热带岩芯（Blake Ridge Plateau的ODP 994C孔）的浮游有孔虫组合更替指数（ATI）的比较表明，热带地区的平均值低于亚热带地区。ODP孔1261A的ATIs峰值并不像ODP孔994C那样与间冰期的开始一致，限制了其广泛相关性的使用。这些地核间ATIs值中位数的显著差异归因于不同纬度的加热差异，暖水物种对热带环流贡献最大，并主导可解释的主成分负荷。大球藻和粘球藻的显著相关性表明，上升流导致了一些峰值组合的更替。相反，gloigerinoides rubberpink和Neogloboquadrina dutrei之间没有显著的相关性，这表明附近的亚马逊河对Demerara隆起的组合更替的影响并不大，核心的赤道位置和上升流的影响更大。此外，浮游有孔虫物种比例丰度的序列变化表明，在冰川终止期间，上升流、温跃层深度和海平面都发生了变化。该研究表明，ATI的使用突出了影响单个浮游有孔虫物种和总体组合的多重因素。然而，了解区域因素对于有效利用ATI作为生态地层学工具至关重要。

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引用次数: 0

Living (stained) benthic foraminifera from Southern Brazilian Margin: A comparative study in different soft sediments size fractions and strata 巴西南部边缘活底栖（染色）有孔虫：不同软沉积物粒度组分和地层的比较研究

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-29 DOI: 10.1016/j.marmicro.2025.102506

Ana Cláudia Aoki Santarosa , Cintia Yamashita , Thaisa Marques Vicente , Maria Virginia Alves Martins , Daniel Leite Moreira , Silvia Helena de Mello e Sousa

Living (stained) benthic foraminifera from deep-sea stations in the Southern Brazilian Margin were studied to compare distribution patterns across the 63–125 μm and > 125 μm size fractions 0–1 and 1–2 cm intervals. Statistical testsconfirmed the presence of significant differences between the two sediment layers and size fractions. The superficial level showed higher density of specimens and species richness. In addition, the sediment layers show distinct species composition. The most abundant and frequent species in the 0–1 cm were Globocassidulina subglobosa, Epistominella exigua, Alabaminella weddellensis, Reophax sp. 1, Seabrookia curta, Bolivina albatrossi, Reophax tortilis, and Trifarina bradyi. Among the 96 exclusive species from the 1–2 cm, we found: Arenoparrella mexicana, Haplophragmoides fragile, Triloculinella pseudooblonga, Technitella harrisii, and Bolivina pacifica. Regarding the different size fractions, the >125 μm fraction showed lower density of specimens but higher diversity and the benthic foraminiferal assemblages had an average of 65 % agglutinated and 33 % calcareous species. The most abundant species were Reophax sp. 1, Thurammina sp. 1, Lagenammina sp. 1, Uvigerina peregrina, and Reophax scorpiurus. In the 63–125 μm size fraction, benthic foraminiferal assemblages comprised 53 % agglutinated and 43 % calcareous species, showing that the proportions of agglutinated species decreased. The most abundant species in the finer fraction were Alabaminella weddellensis, Epistominella exigua, Globocassidulina subglobosa, Seabrookia curta, and Bolivina albatrossi. Based on the statistically different results of the diversity indices, as well as the distinctive composition of species between the two layers and size fractions, we recommend the use of the >63 μm size fraction and 0–2 cm for future studies on benthic foraminifera in oligotrophic deep-sea areas.

研究了巴西南部深海站的活底栖有孔虫（染色），比较了63-125 μm和125 μm大小的0-1和1-2 cm间隔的分布模式。统计试验证实了两种沉积层和粒度之间存在显著差异。表层具有较高的标本密度和物种丰富度。此外，沉积层显示出明显的物种组成。0 ~ 1 cm范围内最丰富和最常见的物种是Globocassidulina subglobosa、Epistominella exigua、Alabaminella weddellensis、Reophax sp. 1、Seabrookia curta、Bolivina albatrossi、Reophax tortilis和Trifarina bradyi。在1 ~ 2 cm范围内的96种特有种中，发现有墨西哥细粒细粒菌（Arenoparrella mexicana）、易碎Haplophragmoides脆性菌（Haplophragmoides fragile）、伪长三角菌（Triloculinella pseudobloonga）、哈里氏技术菌（Technitella harrisii）和太平洋玻利维亚菌（Bolivina pacifica）。在不同粒径组分中，125 μm组分的标本密度较低，但多样性较高，底栖有孔虫的黏结种类平均为65%，钙质种类平均为33%。最丰富的种类为食螨1、土耳螨1、Lagenammina 1、长耳螨1和Reophax scorpiurus。在63 ~ 125 μm粒径的底栖有孔虫组合中，凝集菌占53%，钙质菌占43%，表明凝集菌的比例有所下降。细粒区最丰富的物种为weddellella、Epistominella exigua、Globocassidulina subglobosa、Seabrookia curta和Bolivina albatrossi。基于多样性指数的统计差异，以及两层间物种组成和粒径组分的差异，我们建议在未来的研究中使用63 μm粒径组分和0-2 cm的底栖有孔虫。

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引用次数: 0

A rapid method for measuring ancient coccolith size 一种快速测量古球粒大小的方法

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-08-25 DOI: 10.1016/j.marmicro.2025.102504

Ruby Barrett , Ann Power , John Love , Daniela. N. Schmidt

Coccolithophores are single-celled phytoplankton that produce calcite plates called coccoliths. Coccolithophores play a key role in long-term ocean carbon storage through the sedimentation and burial of their calcite (calcium carbonate) exoskeletons. Coccolith size is important in determining how much carbonate is ultimately buried. We present a novel method for measuring ancient coccolith size using imaging flow cytometry combined with cross-polarised light (ISX^+PL). This technique provides a rapid and high throughput alternative to manual and existing automated techniques by enabling the analysis of ≈1000 objects per second without time-consuming slide preparation. We have applied ISX^+PL to the fossil record for the first time, and as a proof of method, analysed samples from Goban Spur (DSDP Site 548) and Ceara Rise (ODP Site 925/9) to reconstruct 66 million years of coccolith size. We show that data obtained from ISX^+PL is consistent with published coccolith size trends, including the reported decrease in size toward the modern. Changes in coccolith size below 3 μm should be treated with caution because this exceeds the accuracy of the method. The inexpensive, rapid, and less labour intensive approach increases the speed of analysis compared to existing methods. The ISX^+PL method enables users to analyse more samples, increase the robustness of their dataset due to a high specimen count (≈10,000 per sample), and explore a wealth of morphological features recorded in the digital images of coccoliths. The method offers flexibility, enabling users to adapt it to their needs—for instance, by targeting specific morphologies—thereby expanding its applicability.

球石藻是单细胞浮游植物，产生方解石板，称为球石岩。球石藻通过其方解石（碳酸钙）外骨骼的沉积和埋藏，在长期的海洋碳储存中起着关键作用。球粒岩的大小对于确定最终埋藏了多少碳酸盐非常重要。我们提出了一种利用成像流式细胞术结合交叉偏振光（ISX+PL）测量古球粒大小的新方法。该技术为人工和现有的自动化技术提供了一种快速、高通量的替代方法，每秒可以分析约1000个物体，而无需耗时的玻片制备。我们首次将ISX+PL应用于化石记录，并分析了Goban Spur （DSDP Site 548）和Ceara Rise （ODP Site 925/9）的样品，重建了6600万年的球粒大小。我们发现从ISX+PL获得的数据与已发表的球粒石尺寸趋势一致，包括报告的尺寸向现代减小。球粒尺寸小于3 μm的变化应谨慎处理，因为这超出了方法的精度。与现有方法相比，这种廉价、快速、劳动密集程度较低的方法提高了分析速度。ISX+PL方法使用户能够分析更多的样品，由于高标本计数（每个样品≈10,000个），增加了数据集的鲁棒性，并探索了在球粒石的数字图像中记录的丰富形态特征。该方法提供了灵活性，使用户能够根据自己的需求进行调整——例如，针对特定的形态——从而扩大其适用性。

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引用次数: 0