Marine Micropaleontology最新文献_第3页

History of current circulation and bottom redox conditions in the central Okinawa Trough over the last 19 ka: Foraminiferal and element geochemical records 近19ka来冲绳海槽中部环流和底部氧化还原条件的历史：有孔虫和元素地球化学记录

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-12-04 DOI: 10.1016/j.marmicro.2025.102538

Feifei Wang , Bangqi Hu , Jingtao Zhao , Deqing Weng , Jianwei Guo , Xue Ding

The Okinawa Trough (OT) is a critical archive of western Pacific paleoceanography, yet the glacial-interglacial evolution of its circulation and bottom-water redox conditions remain poorly constrained. This study provides a multi-proxy reconstruction from core CS2 in the central OT, revealing a 19-ka history of Kuroshio Current (KC) and intermediate water ventilation for bottom-water oxygenation. Our results show that during the last glaciation, lower sea levels isolated the trough, reducing KC inflow as evidenced by decreased abundances of tropical-subtropical planktonic foraminifera and a shoaled thermocline. Concurrently, bottom-water hypoxia developed, indicated by elevated infaunal benthic foraminifera, lower Mn/Al ratios, and reduced CaCO₃ content, collectively suggesting that the absence or shift of KC was the primary driver of poor ventilation. Furthermore, an anti-phase relationship between hypoxia intensity and North Pacific Intermediate Water (NPIW) ventilation can be observed: enhanced NPIW ventilation (Heinrich Stadial 1 and Younger Dryas) corresponded to weakened hypoxia, whereas reduced ventilation during the Bølling/Allerød intensified hypoxia. The consistently low CaCO₃ content precluded the possibility of hypoxia caused by organic matter consumption, further supporting the conclusion that glacial NPIW ventilation might be another modulator of bottom water oxygenation. During the postglacial period, the return of the KC into the OT improved bottom-water ventilation by reducing stratification and alleviated hypoxia. This study elucidates the evolution of circulation and bottom-water redox conditions to better understand organic carbon burial in the OT. Furthermore, the redox history provides a key mid-latitude archive for assessing the influence of glacial NPIW.

冲绳海槽（OT）是西太平洋古海洋学的重要档案，但其环流和底水氧化还原条件的冰期-间冰期演化仍不清楚。本研究通过对东部中部CS2岩心的多代理重建，揭示了黑潮（KC）的19 ka历史和中水通气的底水氧合。结果表明，在末次冰期，较低的海平面隔离了海槽，减少了KC流入，热带-亚热带浮游有孔虫丰度减少，温跃层变浅。同时，底水缺氧发展，表现为底部底栖有孔虫数量增加，Mn/Al比降低，CaCO3含量降低，共同表明KC的缺失或转移是通风不良的主要驱动因素。此外，缺氧强度与北太平洋中水（NPIW）通气之间存在反相位关系：NPIW通气增强（Heinrich Stadial 1和Younger Dryas）对应于缺氧减弱，而Bølling/ allerd期间通气减少则强化了缺氧。持续的低CaCO3含量排除了有机物消耗引起缺氧的可能性，进一步支持了冰川NPIW通气可能是底水氧合的另一个调节剂的结论。在冰期后，KC返回到OT通过减少分层和缓解缺氧改善了底水通风。本研究阐明了循环演化和底水氧化还原条件，以更好地了解第三系有机碳埋藏。此外，氧化还原历史为评估冰川NPIW的影响提供了一个关键的中纬度档案。

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引用次数: 0

Linkages between modern benthic foraminiferal assemblages and environmental conditions at continental slope depths: From Baffin Bay to the Labrador Sea 现代底栖有孔虫组合与大陆斜坡深度环境条件之间的联系：从巴芬湾到拉布拉多海

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-12-01 DOI: 10.1016/j.marmicro.2025.102527

Joanna Davies , Anne Jennings , Alice Carter-Champion , William J. D'Andrea , Cara Fritz , Erin E. Gregory , David J. Harning , Robert Kelleher , Alan C. Mix , Katherine Stelling , Joseph S. Stoner , Maureen H. Walczak , Shannon Klotsko , Robert G. Hatfield , Brendan Reilly

Analysis of benthic foraminiferal assemblages and lipid biomarkers from surface sediments at 10 sites along the Greenland margin in Baffin Bay, in the Davis Strait, and Labrador Sea, spanning both shallow (<1000 m) and deep (>1000 m) water depths, reveals key differences related to environmental gradients. The relative abundance of calcareous and agglutinated foraminifera differentiates sites; deeper Baffin Bay sites are dominated by agglutinated taxa, while shallower Baffin Bay sites and a site in the Labrador Sea are characterised by calcareous taxa. Correlations amongst calcareous species and environmental parameters, specifically bottom water temperature and salinity from CTD casts, sea ice, open water phytoplankton biomarker concentrations and total organic carbon, suggest that carbonate dissolution is associated with seasonal sea-ice formation, cold and less saline bottom waters, and high primary productivity. Cassidulina neoteretis and Cassidulina reniforme are abundant at almost all sites, reflecting the presence of chilled Atlantic sourced water. In eastern Davis Strait, sea ice is absent for much of the year and the faunal assemblage is dominated by calcareous taxa, specifically Nonionellina labradorica, Elphidium clavatum, Epistominella arctica and Melonis barleeanus. In the Labrador Sea, which is characterised by warmer bottom waters and less seasonal sea-ice, the fauna differs from Baffin Bay, dominated by Buccella frigida and Nonionella iridea. Agglutinated taxa, particularly Portatrochammina bipolaris, Hormosinelloides guttifera, Lagenammina difflugiformis and Recurvoides turbinatus, dominate Baffin Bay sites, where cold, sea-ice-influenced bottom waters prevail. Linking faunal assemblages, including agglutinated taxa, to environmental datasets is critical for paleoenvironmental reconstructions, especially in regions where calcareous foraminifera are poorly preserved.

对巴芬湾格陵兰边缘、戴维斯海峡和拉布拉多海10个地点的表层沉积物中底栖有孔虫组合和脂质生物标志物的分析，跨越了浅（<1000 m）和深（>1000 m）水深，揭示了与环境梯度相关的关键差异。钙质有孔虫和凝集有孔虫的相对丰度不同；较深的巴芬湾遗址以粘连类群为主，而较浅的巴芬湾遗址和拉布拉多海的一个遗址以钙质类群为特征。钙质种类与环境参数的相关性，特别是CTD cast的底水温和盐度、海冰、开放水域浮游植物生物标志物浓度和总有机碳，表明碳酸盐溶解与季节性海冰形成、寒冷和低盐底水以及高初级生产力有关。几乎在所有的地点都有大量的小木犀草（Cassidulina neteretis）和长形木犀草（Cassidulina reniforme），这反映了来自大西洋的冷水的存在。在戴维斯海峡东部，海冰常年不存在，动物群以钙质类群为主，特别是Nonionellina labradorica、Elphidium clavatum、Epistominella arctica和Melonis barleeanus。在拉布拉多海，其特点是温暖的底部海水和较少的季节性海冰，动物群不同于巴芬湾，主要是Buccella frigida和Nonionella iridea。凝集的类群，特别是双极紫菀、花叶草、散斑紫菀和turbinatus，主导着巴芬湾的地点，在那里，寒冷，海冰影响的底部水占优势。将动物组合（包括凝集类群）与环境数据集联系起来对于古环境重建至关重要，特别是在钙质有孔虫保存较差的地区。

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引用次数: 0

Evolution of Neogene fossil ceratoliths (Coccolithophores) by duplication 新近系角藻化石（球石藻）的复制演化

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-12-01 DOI: 10.1016/j.marmicro.2025.102530

Carlos Lancis , J.E. Tent-Manclús , Jorge Lancis , Antonio Estévez , José-Abel Flores

The calcareous nannofossils of the genus Ceratolithus, known for their horseshoe shape (referred to as ceratolith), evolved from the Orthorhabdus rugosus, a rod-shape nannolith with three rodded blades (sinistral, median, and dextral). The sinistral and median blades gave rise to the sinistral and dextral arms of the ceratolith, while the dextral blade was reduced to a keel. The first species of the Ceratolithus genus branch is Ceratolithus finifer, which rapidly evolved into Ceratolithus acutus. Around at the same time, the merging of three duplicated, delicate horseshoe-shaped structures derived from C. finifer - two equivalent and one a mirror image of the other- resulted in the short-lived Poralithus atlanticus (5.32 to 5.17 Ma). Later on, two duplicated horseshoe-shaped structures oriented at an angle of approximately 45° and fused at the horseshoe's close side, produced Amaurolithus tricorniculatus (5.30 to 4.86 Ma). The crystallographic features of A. tricorniculatus points to a possible origin by two duplicated Ceratolithus-type horseshoes (birefringent in its stable layout) and derived from C. finifer. Being the type species of the Amaurolithus genus and also evolving from the Ceratolithus branch, then the early ‘Amaurolithus’, which evolved from O. rugosus, have been placed in a newly defined Protoamaurolithus genus, as Protoamaurolithus primus and Protoamaurolithus delicatus. Best-preserved Amaurolithus tricorniculatus specimens are observed to show birefringence and the broken and poor-preserved use to be slightly or not birefringence. Poralithus atlanticus and Amaurolithus tricorniculatus appeared instantly in the geologic record, indicative of instantaneous speciation, resulting from horseshoe-structure duplication process.

角鼻石属的钙质纳米化石，以其马蹄形而闻名（称为角鼻石），由Orthorhabdus rugosus进化而来，Orthorhabdus rugosus是一种杆状的纳米石，有三个杆状的叶片（左旋、中旋和右旋）。左旋和中旋叶片形成了角状石的左旋和右旋臂，而右旋叶片则退化为龙骨。角鼻蠓属分支的第一个种是尖角角蠓，并迅速进化为尖角蠓。大约在同一时间，来自C. finifer的三个重复的、精致的马蹄形结构的合并——两个相同，一个是另一个的镜像——产生了寿命较短的大西洋Poralithus（5.32至5.17 Ma）。后来，两个重复的马蹄形结构以约45°的角度定向，并在马蹄形的近侧融合，产生了Amaurolithus tricorniculatus（5.30至4.86 Ma）。a . tricorniculatus的晶体学特征表明其可能来源于C. finifer的两个重复的ceratolithus型马蹄铁（其稳定的双折射结构）。作为毛毛蜥属的模式种，也是由角鼻蜥分支进化而来的，因此早期的“毛毛蜥”从O. rugosus进化而来，被置于一个新定义的原毛毛蜥属，即原毛毛蜥primus和原毛毛蜥delicatus。保存较好的三环蛇标本显示双折射，而破损和保存较差的标本显示轻微或无双折射。在地质记录中，大西洋Poralithus atlanticus和三环蛇amaurollithus tricorniculatus是瞬时出现的，表明它们是由马蹄形结构复制过程产生的瞬时物种形成。

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引用次数: 0

Bioerosion traces and encrustations on orbitolinid tests from the upper Barremian (Lower Cretaceous) of Kopet-Dagh Basin, northeastern Iran 伊朗东北部Kopet-Dagh盆地上巴雷米亚（下白垩纪）的生物侵蚀痕迹和轨道线测试的结壳

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-11-19 DOI: 10.1016/j.marmicro.2025.102529

Mir Amir Salahi , Sreepat Jain

Studies on bioerosion traces and encrustations on orbitolinid tests are relatively less documented in comparison with other larger benthic foraminifera such as nummulitids and other micro-organisms. Hence, as such, these epibionts are difficult to detect in the fossil record, probably because of less working of bioerosional processes on orbitolinids. We document bioerosion traces and encrustations on the orbitolinid Paleodictyoconus from the upper Barremian rocks of the Sarcheshmeh Formation, Kopet-Dagh Basin (north-eastern Iran). Based on the study of 155 samples, four bioerosion ichnotaxa, Entobia, Trypanites, Oichnus, and Gastrochaenolites, along with encrustations by nubeculariid foraminifera, bryozoans, and a coral, are documented. These assemblages are attributed to the Entobia ichnofacies. Additionally, due to their abundance and larger test size, the orbitolinids attached to the bivalve Pinna were also a preferred substrate to settle for the larvae of smaller benthic foraminifera, as noted herein. Coincident with previous studies, the high percentage of borings and encrustation also alludes to calm waters, low rates of sedimentation, and a protected setting, thus, also favouring larval settlement on orbitolinid tests.

与其他大型底栖有孔虫（如nummultiides和其他微生物）相比，关于生物侵蚀痕迹和眼窝石试验结壳的研究文献相对较少。因此，这些表观生物在化石记录中很难被发现，可能是因为生物侵蚀过程对眼窝石的作用较少。我们记录了来自伊朗东北部Kopet-Dagh盆地Sarcheshmeh组上Barremian岩石的轨道状古dictyoconus的生物侵蚀痕迹和结壳。基于155个样品的研究，记录了四个生物侵蚀鱼类群，即Entobia，锥虫，Oichnus和Gastrochaenolites，以及核虫有孔虫，苔藓虫和珊瑚的结壳。这些组合可归因于东非的沉积相。此外，如本文所述，由于它们的丰度和更大的测试尺寸，附着在双壳类耳蜗上的耳蜗也是较小的底栖有孔虫幼虫的首选基质。与以前的研究一致，钻孔和结壳的高比例也暗示了平静的水域、低沉降率和受保护的环境，因此也有利于幼虫在眼眶测试中定居。

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引用次数: 0

Late Holocene paleoceanography of the Knipovich Ridge area (Norwegian Sea) based on micropaleontological data 基于微体古生物资料的挪威海Knipovich Ridge地区晚全新世古海洋学研究

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-11-05 DOI: 10.1016/j.marmicro.2025.102526

Tatiana S. Klyuvitkina , Ekaterina A. Novichkova , Elizaveta A. Agafonova , Lubov A. Lozinskaia , Karina S. Iakimova , Alexander G. Matul , Maria P. Chekhovskaya , Rahul Mohan , Anne de Vernal

The marine environmental conditions of the last 2.9 cal ka in the Knipovich Ridge area, Norwegian Sea, were reconstructed using micropaleontological and sedimentological data and quantitative estimations of sea-ice cover, surface and subsurface temperatures and salinity. From 2.9 to 2.2 cal kyr BP, harsh conditions prevailed throughout the entire water column, accompanied by low bottom-current activity, which we associate with the final phase of the Neoglacial cooling. A substantial change in the marine environment towards warming and establishment of modern-like oceanic conditions occurred at 2.2 cal kyr BP simultaneously in surface, subsurface and bottom waters. Dinocyst and diatom data suggest the warmest period in surface waters was recorded at 2.2–1.2 cal kyr BP, followed by a short-lived cooling at 1.0–1.2 cal kyr BP marked by sea ice recurrence. Another major shift in ocean conditions occurred at 0.6 cal kyr BP, corresponding to the onset of the Little Ice Age (LIA) and showing decoupling in surface and subsurface water layers. According to our records, the LIA cooling signal in the Knipovich Ridge area was only evident in the upper water layer, without changes throughout the water column. The regional LIA cooling could be associated with cold surface currents from the Barents Sea shelf flowing into the Norwegian Sea in summer.

利用微古生物学和沉积学资料，以及海冰覆盖、地表和地下温度和盐度的定量估算，重建了挪威海Knipovich Ridge地区最近2.9 cal ka的海洋环境条件。从2.9 - 2.2 cal kyr BP，整个水柱的条件都很恶劣，伴随着低底流活动，我们将其与新冰期冷却的最后阶段联系起来。在2.2 calkyr BP，海面、地下和海底同时发生了海洋环境向变暖方向的实质性变化和类似现代海洋条件的建立。藻囊和硅藻资料表明，地表水最温暖的时期记录在2.2-1.2 cal kyr BP，随后是1.0-1.2 cal kyr BP的短暂降温，标志着海冰的复发。另一次海洋条件的重大转变发生在0.6 cal kyr BP，与小冰期（LIA）的开始相对应，并显示了表层和次表层水层的分离。根据我们的记录，Knipovich Ridge地区的LIA冷却信号仅在上层水层明显，整个水柱没有变化。区域性低气压变冷可能与夏季从巴伦支海陆架流入挪威海的冷表面流有关。

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引用次数: 0

Seasonal variations of recent benthic foraminifera in the surface sediments of Kongsfjorden, Svalbard 斯瓦尔巴群岛kongsjorden表层沉积物中近代底栖有孔虫的季节变化

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-11-04 DOI: 10.1016/j.marmicro.2025.102528

Patrycja Jernas , Katrine Husum , Dorthe Klitgaard-Kristensen , Matthias Forwick , Marta Głuchowska , Nalan Koç

The objective of this study is to investigate the seasonal variability of benthic foraminifera and to identify environmental factors influencing the observed faunal changes. Surface sediment sampling, hydrological measurements, and measurements of the pelagic production were carried out along a transect of four stations in Kongsfjorden, Svalbard, European Arctic, in the early spring, summer and autumn of 2008 and in spring 2009. The most dominant species was Nonionellina labradorica. The majority of the observed faunal variability can be explained by seasonal changes in bottom-water temperature together with suspended matter of glacial origin, as well as by the food availability controlled by pelagic production. During spring, when the amount of freshly deposited organic matter onto the fjord bottom was high, the absolute abundance of living benthic foraminifera could increase up to eightfold compared to other seasons. Most of the species occupied the upper 0–1 cm of the sediment column, while N. labradorica and G. auriculata preferred the 1–2 cm interval. Adercotryma glomeratum, E.excavatum f. clavatum, R. scorpiurus and R. arctica seem to migrate to deeper habitats during the low-productive period. This behaviour may be indicative of a survival adaptation during low food-quality seasons when the species choose deeper levels, thus, reducing the risk of competition and predation during periods of low food availability, while also benefiting from better oxygen penetration.

本研究的目的是调查底栖有孔虫的季节变化，并确定影响观察到的动物区系变化的环境因素。在2008年早春、夏季和秋季以及2009年春季，沿着欧洲北极斯瓦尔巴群岛Kongsfjorden的四个站点的样带进行了地表沉积物采样、水文测量和上层海洋生产测量。优势种为拉布拉多丽草（Nonionellina labradorica）。大多数观测到的动物群变异可以用底水温的季节性变化以及冰川起源的悬浮物，以及由远洋生产控制的食物供应来解释。在春季，当新鲜沉积到峡湾底部的有机物量很高时，生活的底栖有孔虫的绝对丰度可能比其他季节增加8倍。大部分种类分布在沉积物柱的上部0 ~ 1 cm，而拉布拉多丽卡和金耳丽卡更倾向于1 ~ 2 cm。在低产期，肾小球皮霉、凹形皮霉、天蝎皮霉和北极皮霉似乎会向较深的生境迁移。这种行为可能表明，在食物质量较低的季节，当物种选择较深的层次时，生存适应了，因此，在食物供应不足的时期，减少了竞争和捕食的风险，同时也受益于更好的氧气渗透。

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引用次数: 0

Size variation of Eprolithus floralis across Oceanic Anoxic Event 2 (Late Cretaceous) in the Eastbourne section 伊斯特本剖面洋缺氧事件2（晚白垩世）中Eprolithus floralis的大小变化

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-10-27 DOI: 10.1016/j.marmicro.2025.102525

Edna de Jesus Francisco Tungo , Elisabetta Erba , Gerson Fauth , Cinzia Bottini

Morphometric analyses of Eprolithus floralis were conducted in the Eastbourne section (southeast England, UK) to quantify size changes of this nannofossil species across Oceanic Anoxic Event 2 (OAE 2; Cenomanian/Turonian boundary, ∼94 Ma). The total and inner diameters exhibit a reduction of 3 % and 2.4 %, respectively, relative to the overall mean size during OAE 2 with minimum values (∼1 μm smaller) occurring at carbon isotope peak B. A recovery of 8.4 % and 5.7 % in two distinct morphotypes were identified: the rounded morphotype is ca. 0.5 μm smaller than the spiky one and starts to be more abundant just prior to OAE 2. The spiky morphotype accounts for 61 % before and 56 % after OAE 2 where it also shows largest average sizes and the smallest diaphragm. Morphometric shifts coincide with the onset of intense volcanism from the Caribbean Plateau whereas the size increase parallels the decline in volcanic activity, suggesting a possible link between environmental recovery and morphological diversification.

Size and abundance minima of E. floralis and Biscutum constans at peak B suggest a shared physiological response, likely reduced calcification, to maximum environmental stress and possibly ocean acidification. However, E. floralis shows earlier size recovery, indicating higher ecological tolerance. No clear correlation is found with the Plenus Cold Event, excluding temperature as a primary control of E. floralis abundance and size.

在伊斯特本剖面（英国英格兰东南部）对Eprolithus floralis进行了形态计量学分析，以量化这种纳米化石物种在海洋缺氧事件2 （OAE 2； Cenomanian/Turonian边界，~ 94 Ma）中的大小变化。与OAE 2期间的总体平均粒径相比，总直径和内径分别减小了3%和2.4%，最小值（约小1 μm）出现在碳同位素峰b处。在两种不同的形态中，回收率分别为8.4%和5.7%：圆形形态比尖状形态小约0.5 μm，在OAE 2之前开始更加丰富。尖尖型在OAE 2之前占61%，在OAE 2之后占56%，其中它也显示出最大的平均尺寸和最小的隔膜。形态变化与加勒比高原强烈火山活动的开始相一致，而大小的增加与火山活动的减少相一致，这表明环境恢复与形态多样化之间可能存在联系。在B峰，E. floralis和饼干常数的大小和丰度最小值表明对最大的环境压力和可能的海洋酸化有共同的生理反应，可能是减少钙化。而花金莲的大小恢复较早，表明其生态耐受性较高。除温度是影响花莲丰度和大小的主要因素外，未发现与春日寒事件有明显的相关性。

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引用次数: 0

Early Cretaceous radiolarians and siliceous rock geochemistry from Kangmar, Southern Xizang: Biostratigraphic, paleoenvironmental, and paleogeographic implications for the Neo-Tethys Ocean 西藏康玛早白垩世放射虫和硅质岩地球化学：新特提斯洋的生物地层、古环境和古地理意义

IF 1.6 4区地球科学 Q2 PALEONTOLOGY

Marine Micropaleontology

Pub Date : 2025-10-24 DOI: 10.1016/j.marmicro.2025.102523

Han Yan , Hanting Zhong , Chenyu Wang , Zongqi Lin , Cai Wang , Xiachao Huang , Chao Chen , Mingcai Hou

Siliceous rocks from the Daba section, Kangmar area (southern Xizang), yield well-preserved radiolarian assemblages that provide new evidence for constraining the stratigraphic age and depositional setting of the northern Neo-Tethys Ocean. The faunas are dominated by Austral Realm taxa such as Fusitanella, Praewindalia, and Archaeotanella, in close affinity with Early Cretaceous assemblages from the Argo Abyssal Plain (ODP Site 765C). Key index species (Hemicryptocapsa regularis, H. exgyrum, Archaeodictyomitra brouweri) indicate Berriasian–Valanginian and late Barremian–early Aptian ages, thereby revising earlier assignments of these rocks to the Late Cretaceous. Geochemical data (MnO/TiO₂ ratios of 0.19–0.38; Al/(Al + Fe + Mn) values of 0.51–0.58; REE patterns with slight LREE enrichment, weak negative Ce anomaly, and negative Eu anomaly) point to a continental-margin depositional environment. These results not only resolve long-standing age uncertainties but also highlight the significance of Austral radiolarian distribution for reconstructing Early Cretaceous ocean circulation and paleogeography of the Neo-Tethys.

西藏康玛地区大坝剖面的硅质岩显示了保存完好的放射虫组合，为限定新特提斯洋北部的地层年龄和沉积背景提供了新的证据。动物群以Austral Realm类群Fusitanella、Praewindalia和Archaeotanella为主，与Argo深海平原（ODP Site 765C）早白垩世的组合关系密切。关键指标种（Hemicryptocapsa regularis， H. exgyrum, Archaeodictyomitra broweri）显示了berriasia - valanginian和barremian - Aptian早期，从而修正了早期对这些岩石的晚白垩世定位。地球化学数据(MnO/TiO2比值为0.19 ~ 0.38,Al/(Al + Fe + Mn)值为0.51 ~ 0.58；弱LREE富集、弱Ce负异常、弱Eu负异常的稀土模式指向大陆边缘沉积环境。这些结果不仅解决了长期存在的年龄不确定性，而且突出了南放射虫分布对重建早白垩世海洋环流和新特提斯古地理的意义。

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引用次数: 0

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