Marine Micropaleontology最新文献

Foraminiferal image classification based on convolutional neural network considering data augmentation optimization 考虑数据增强优化的卷积神经网络有孔虫图像分类

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-06-06 DOI: 10.1016/j.marmicro.2025.102476

Jincan Wang , Muhui Zhang , Weiping Zeng , Songzhu Gu , Qingzhong Liang , Shuqin Zhou , Zimeng Gao

{"title":"Foraminiferal image classification based on convolutional neural network considering data augmentation optimization","authors":"Jincan Wang , Muhui Zhang , Weiping Zeng , Songzhu Gu , Qingzhong Liang , Shuqin Zhou , Zimeng Gao","doi":"10.1016/j.marmicro.2025.102476","DOIUrl":"10.1016/j.marmicro.2025.102476","url":null,"abstract":"<div><div>Foraminifera are of utmost importance in paleoclimate and marine ecosystem research, with accurate classification being equally vital. Convolutional Neural Networks (CNNs) can realize the automatic classification of foraminiferal images, but they usually rely on data augmentation to address the issue of data scarcity. Despite the widespread use of data augmentation methods, the impacts of various augmentation methods on the classification of foraminifera remain unclear. In this study, we systematically evaluated the effects of different data augmentation methods on the classification performance of CNNs using three publicly available datasets. Experiments based on the ResNet-50 architecture showed that random rotation (RR), random flipping (RF), and random erasing (RE, ratio = 0.2) significantly improved the classification accuracy. The combined model of these three methods achieved accuracies of 89.4 %, 89.7 %, and 95.7 %, and F1 scores of 72.7 %, 72.8 %, and 84.3 % in the three tasks respectively. Compared with the basic model, the accuracy (A) increased by an average of 3.2 %, and the F1 score (F1) increased by an average of 7.1 %. This study confirms that selecting and combining appropriate data augmentation methods can effectively enhance the performance of foraminiferal image classification, with the combination of RR, RF, and RE being the most effective.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"199 ","pages":"Article 102476"},"PeriodicalIF":1.5,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144222400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Environmental history of northwestern Vancouver Island (British Columbia, Canada) during the Holocene: A high-resolution dinoflagellate cyst record from Kyuquot Sound 加拿大不列颠哥伦比亚省温哥华岛西北部全新世环境史：奎括湾高分辨率鞭毛藻囊记录

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-06-02 DOI: 10.1016/j.marmicro.2025.102475

Pieter R. Gurdebeke , Vera Pospelova , Kenneth N. Mertens , Zhen Li , Bjarn Van Riet , Audrey Dallimore , Stephen Louwye

{"title":"Environmental history of northwestern Vancouver Island (British Columbia, Canada) during the Holocene: A high-resolution dinoflagellate cyst record from Kyuquot Sound","authors":"Pieter R. Gurdebeke , Vera Pospelova , Kenneth N. Mertens , Zhen Li , Bjarn Van Riet , Audrey Dallimore , Stephen Louwye","doi":"10.1016/j.marmicro.2025.102475","DOIUrl":"10.1016/j.marmicro.2025.102475","url":null,"abstract":"<div><div>Environmental changes over the Holocene were reconstructed based on the analysis of dinoflagellate cyst assemblages, their absolute abundances, and morphological changes in <em>Operculodinium centrocarpum</em> sensu Wall & Dale 1966 from 103 sediment samples collected from Core 2012002PGC133 in Tahsish Inlet (Kyuquot Sound), a fjord on the west coast of Vancouver Island (British Columbia, Canada). Eight accelerator mass spectrometry <sup>14</sup>C dates indicate that the record spans the last 12 ka. The cysts are well-preserved, with assemblages displaying high diversity (37 taxa). Six dinoflagellate cyst assemblage zones were identified. Zone I is dominated by <em>Operculodinium centrocarpum</em> sensu Wall & Dale 1966, while subsequent zones (II–IV) are characterized mainly by cysts of heterotrophic species. The uppermost zones (V–VI) show increased abundances of autotrophic taxa. The dinoflagellate cyst record reflects regional and global environmental signals. The dominance of <em>Operculodinium centrocarpum</em> sensu Wall & Dale 1966 during the Younger Dryas corresponds to a lower relative sea level, indicative of marsh-like conditions or proximity to the inlet head at the core site. Increased heterotrophic taxa during the late Early and Middle Holocene suggests a rising marine influence due to RSL rise, possibly enhancing primary productivity through coastal upwelling. Reduced process lengths in <em>Operculodinium centrocarpum</em> sensu Wall & Dale 1966 around ∼8.7 cal kyr BP indicate an abrupt change in local environmental conditions. A sharp increase in absolute cyst abundances ∼2.2 cal kyr BP, primarily driven by <em>Spiniferites</em> spp., is proposed to be linked with climate- and tsunami-related mechanisms.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"199 ","pages":"Article 102475"},"PeriodicalIF":1.5,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144289144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Sedimentary record of Polysphaeridium zoharyi (cyst of Pyrodinium bahamense) in El Colorado Lagoon, Gulf of California 加利福尼亚湾El Colorado泻湖Polysphaeridium zoharyi （Pyrodinium bahamense囊肿）的沉积记录

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-05-21 DOI: 10.1016/j.marmicro.2025.102472

Tomasa Cuellar-Martinez, Rosalba Alonso-Rodríguez, Ana Carolina Ruiz-Fernández, Joan-Albert Sanchez-Cabeza

{"title":"Sedimentary record of Polysphaeridium zoharyi (cyst of Pyrodinium bahamense) in El Colorado Lagoon, Gulf of California","authors":"Tomasa Cuellar-Martinez, Rosalba Alonso-Rodríguez, Ana Carolina Ruiz-Fernández, Joan-Albert Sanchez-Cabeza","doi":"10.1016/j.marmicro.2025.102472","DOIUrl":"10.1016/j.marmicro.2025.102472","url":null,"abstract":"<div><div>The temporal variations in abundances (cyst g<sup>−1</sup> and percentages) and fluxes (cyst cm<sup>−2</sup> yr<sup>−1</sup>) of dinoflagellate cysts, including <em>Polysphaeridium zoharyi</em> from the toxic species <em>Pyrodinium bahamense</em>, were analyzed in a <sup>210</sup>Pb-dated sediment core from El Colorado Lagoon (Mexico) to investigate potential natural and/or human-driven factors, influencing the proliferation of <em>P. bahamense</em>, by examining the relationship between <em>P. zoharyi</em> abundance and geochemical indicators of sediment provenance and hydrodynamic conditions. <em>P. zoharyi</em> was the most abundant and frequently observed species along the core. The dominance of <em>P. zoharyi</em> was linked to the prevalence of terrigenous influence in most core sections, implying enhanced nutrient delivery. In recent years (∼1970s), the decrease in <em>P. zoharyi</em> percentages was associated with a local shift in hydrodynamic conditions, as revealed by an increase in sand content, changes in the δ<sup>13</sup>C and δ<sup>15</sup>N composition, and higher concentrations of marine indicator elements (Br, Ca, Na, and Sr). The change in hydrodynamic conditions suggests enhanced connectivity with the sea, likely triggered by a meteorological event. We highlight the importance of integrating multiple geochemical proxies with cyst analysis to assess changes in species assemblages and how local conditions, such as shifts in hydrodynamic conditions, that can influence species composition. This study contributes to paleoecology and phytoplankton ecology by documenting species responses to natural and anthropogenic disturbances. It confirms the recurrence and dominance of <em>P. bahamense</em> cysts, a toxin-producing species associated with harmful algal blooms. The findings underscore the need for continued monitoring, contingency planning, and water quality protection in coastal ecosystems.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"199 ","pages":"Article 102472"},"PeriodicalIF":1.5,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144169576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The genetic isolation of planktonic foraminifera in the North Pacific gyre and adjacent marginal seas 北太平洋环流及其邻近边缘海浮游有孔虫的遗传分离

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-05-21 DOI: 10.1016/j.marmicro.2025.102473

Kate F. Darling , Agnes K.M. Weiner , Atsushi Kurasawa , Takashi Toyofuku , Hiroshi Nishi , Hiroshi Kitazato

{"title":"The genetic isolation of planktonic foraminifera in the North Pacific gyre and adjacent marginal seas","authors":"Kate F. Darling , Agnes K.M. Weiner , Atsushi Kurasawa , Takashi Toyofuku , Hiroshi Nishi , Hiroshi Kitazato","doi":"10.1016/j.marmicro.2025.102473","DOIUrl":"10.1016/j.marmicro.2025.102473","url":null,"abstract":"<div><div>Gaining insight into the speciation processes prevailing in the modern open ocean requires a comprehensive understanding of the spatial dynamics of the planktonic species that inhabit it, calibrated against time. The high-resolution fossil record of the planktonic foraminifera not only provides such insight but also plays a crucial role in the study of past climate. Both rely on understanding how species relate to the current physical and ecological character of the oceanic water masses they inhabit. Within global single cell barcoding and metabarcoding studies of planktonic foraminifera, the North Pacific subtropical and subpolar gyres remain under-sampled, with the capacity to harbour unrecognised ecologically distinct cryptic species. Targeting this issue, <em>Globigerina bulloides</em> specimens were collected during 12 cruises and near shore sampling campaigns throughout the Northern Pacific and marginal seas. Using standard molecular approaches, 406 specimens were genetically characterised and combined with 42 publicly available sequences to provide a fully comprehensive overview of <em>G. bulloides</em> diversity throughout the North Pacific. Of ten globally recognised genotypes, six (Ia, Ic, Id, IIa, IId, IIf) inhabit the water masses south of the Subpolar Front, with only a single genotype (IIe) inhabiting the vast Subpolar gyre and marginal seas. Genetic isolation was found to prevail throughout both the western subtropical waters (Types Ic and Id) and subpolar waters (Type IIe) of the North Pacific together with the North and South Pacific eastern boundary currents (Type IId). Unlike the Atlantic, bipolarity does not occur between the North Pacific and the Southern Ocean subpolar/polar pelagic biomes.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"199 ","pages":"Article 102473"},"PeriodicalIF":1.5,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144222401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Extant benthic foraminifera from the Indonesian seas: An update of what we know so far and implications for future studies 印度尼西亚海域现存底栖有孔虫：迄今为止我们所知道的最新情况及其对未来研究的影响

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-05-01 DOI: 10.1016/j.marmicro.2025.102471

Sinatrya D. Prayudi , Suhartati M. Natsir , Michael A. Kaminski

{"title":"Extant benthic foraminifera from the Indonesian seas: An update of what we know so far and implications for future studies","authors":"Sinatrya D. Prayudi , Suhartati M. Natsir , Michael A. Kaminski","doi":"10.1016/j.marmicro.2025.102471","DOIUrl":"10.1016/j.marmicro.2025.102471","url":null,"abstract":"<div><div>To offer a comprehensive understanding of the diversity of benthic foraminifera in the Indonesian seas, we analyzed more than 70 years of datasets from both local and international sources. By reviewing articles covering three major biogeographical regions—Sunda Shelf, Sahul Shelf, and Wallacea—and their varying environmental conditions and depositional environments, we identified a total of 1164 species (including uncertain and genus-level identifications) belonging to 448 genera, 136 families, 14 orders, and four classes, in addition to 1116 genus-level naming (sp. and spp.). Our analysis also revealed 762 instances of taxonomic misnaming, with errors stemming from the use of unaccepted names and confusion between fossils, planktonic, and benthic assemblages. Additionally, most of the reviewed studies were found to be incomplete due to insufficient oceanographic data and a lack of detailed species counts, despite the importance of these factors in such research. This work establishes a robust baseline for future studies and highlights key issues that need to be addressed to avoid repeating past uncertainties and to promote more focused research on benthic foraminifera in the region.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"197 ","pages":"Article 102471"},"PeriodicalIF":1.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144098555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Early impacts of Arctic amplification in the western North Water Polynya: A 400-year perspective 北极放大对北水峡西部的早期影响：400年的视角

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-05-01 DOI: 10.1016/j.marmicro.2025.102470

Kelsey A. Koerner , Audrey Limoges , Emily Pike-Connolly , Nicolas Van Nieuwenhove , André Rochon

{"title":"Early impacts of Arctic amplification in the western North Water Polynya: A 400-year perspective","authors":"Kelsey A. Koerner , Audrey Limoges , Emily Pike-Connolly , Nicolas Van Nieuwenhove , André Rochon","doi":"10.1016/j.marmicro.2025.102470","DOIUrl":"10.1016/j.marmicro.2025.102470","url":null,"abstract":"<div><div>The North Water (NOW) polynya in northern Baffin Bay is known for persistent open water, attracting marine mammals and birds during winter. Ice bridges forming north of the NOW at constriction points in Nares Strait aid in sustaining these open water conditions. However, Arctic Amplification has weakened these ice bridges, altering water and sea ice flow into the NOW. We examined the effect of climate warming and recent ice bridge failures through 400 years of changes in the western NOW. We analyzed dinoflagellate cyst (dinocyst) assemblages in a surface sediment transect across the NOW to assess their distribution as indicators of surface water masses. We then analyzed dinocysts and geochemical proxies (carbon and nitrogen signatures) from two sediment cores in the western NOW. Results show the eastern NOW, influenced by the West Greenland Current (WGC), exhibits higher contributions of mixotrophic taxa and total dinocyst concentrations than the western region, influenced by Arctic water outflow. Sediment cores show a 300-year period of stability in the western NOW (1620–1920 CE), followed by an increase in mixotrophic taxa and total dinocyst fluxes, predating observed ice bridge failures. Around 1980 CE, higher abundances of <em>Operculodinium centrocarpum</em>, and cysts of <em>Polarella glacialis</em> and <em>Pentapharsodinium dalei</em>, suggest early sea ice retreat, seemingly attributable to increased WGC influence. These findings demonstrate the early impact of Arctic Amplification on the NOW, with significant changes starting in the first half of the 20th century, which contribute to understanding the timing and propagation of oceanographic changes in the polynya.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"197 ","pages":"Article 102470"},"PeriodicalIF":1.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143922850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Deep-sea benthic foraminifera respond to rapid environmental changes in the central Red Sea during the last glacial period 末次冰期红海中部深海底栖有孔虫对快速环境变化的响应

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-05-01 DOI: 10.1016/j.marmicro.2025.102474

Raphaël Hubert-Huard , Yvonne Milker , Gerhard Schmiedl

{"title":"Deep-sea benthic foraminifera respond to rapid environmental changes in the central Red Sea during the last glacial period","authors":"Raphaël Hubert-Huard , Yvonne Milker , Gerhard Schmiedl","doi":"10.1016/j.marmicro.2025.102474","DOIUrl":"10.1016/j.marmicro.2025.102474","url":null,"abstract":"<div><div>This study investigates the response of deep-sea benthic foraminifera to changes in food fluxes and dissolved bottom water oxygen in the central Red Sea during the last glacial period (Marine Isotope Stages (MIS) 3 and 4). To assess variations in nutrient intrusion from the Arabian Sea and regional organic matter fluxes, we developed the Red Sea Productivity Index (RSPI) based on changes in sea level and African-Arabian monsoon intensity. We found four distinct species groups, each reflecting different ecological niches and opportunistic behavior. Overall, the fauna of MIS 3 is dominated by the generalist species <em>Bolivina subreticulata</em>, which co-occurs or alternates with other preferentially infaunal taxa of varying opportunistic responses. Changes in the dominance of the different species are primarily controlled by seasonal productivity and associated quantity and quality of available organic matter at the sea floor. This is reflected by a close correspondence of the RSPI and a succession of infaunal species, including <em>Uvigerina juncea</em> s.l., and <em>Bolivina variabilis</em> as the most opportunistic taxa, adapted to strong seasonal food pulses. The succession of the species groups are influenced by millennial-scale changes of the African-Arabian monsoon system and Red Sea deep-water ventilation. This suggests a close link to both low- and high-latitude Northern Hemisphere climate variability. Changes in glacial deep-water oxygenation seem to play an important role during MIS 4, when the dominance of <em>Bolivina persiensis</em> indicates a vertical expansion of the oxygen minimum zone. The high glacial deep-water salinities during sea-level lowstands also fostered the occurrence of miliolid taxa.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"197 ","pages":"Article 102474"},"PeriodicalIF":1.5,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144135128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Benthic ostracods as environmental proxies in Nile Delta Coastal Lagoon 尼罗河三角洲沿海泻湖底栖介形类环境指标研究

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-04-23 DOI: 10.1016/j.marmicro.2025.102469

Sherif M. El Baz , Abd-ElMonsef A. El-Badry , Pamela Hallock , Ahmed M. BadrElDin

{"title":"Benthic ostracods as environmental proxies in Nile Delta Coastal Lagoon","authors":"Sherif M. El Baz , Abd-ElMonsef A. El-Badry , Pamela Hallock , Ahmed M. BadrElDin","doi":"10.1016/j.marmicro.2025.102469","DOIUrl":"10.1016/j.marmicro.2025.102469","url":null,"abstract":"<div><div>The coastal Nile Delta wetlands are essential in the protection of the cultivated deltaic land against sea level rise and are major resources for biodiversity and fisheries productivity. The Manzala Lagoon ranks highly polluted among the lacustrine coastal environments of the Nile Delta of Egypt. The environmental quality of the lagoon plummeted a few decades ago with the increase in massive quantities of untreated mixed discharges (agricultural, industrial, and municipal). To evaluate the environmental status of the lagoon requires both geochemical analyses and bioindicators. Total organic carbon and concentrations of seven potentially toxic elements (Pb, Cu, Cd, Zn, Ni, Co, Fe) were determined in 25 sediment samples collected during summer 2014, from which three pollution indices were calculated (Contamination Factor, Degree of Contamination, and Pollution Loading Index). In addition, ostracod assemblages were assessed in the very-fine and fine sand-size fractions of the sediments. The lagoonal environment is characterized by low total dissolved solids, abundant organic matter, heavy metal contamination by Pb, Co, Ni, and especially Cd, and low diversity ostracod assemblages. Six fresh- and brackish water ostracod species were documented, but the assemblage was overwhelmingly dominated (>98 %) by stress-tolerant <em>Cyprideis torosa.</em> While this species correlated strongly with total dissolved solids and fine sediment textures, overall, the limited ostracod diversity and dominance of a stress-tolerant species reflects the compromised ecological quality of Manzala Lagoon.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"197 ","pages":"Article 102469"},"PeriodicalIF":1.5,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Ostracod and foraminiferal assemblages in Tébessa (Northeast Algeria): Insights into Santonian cooling effects Tébessa（阿尔及利亚东北部）的底栖动物和有孔虫组合：洞察桑顿纪的冷却效应

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-04-14 DOI: 10.1016/j.marmicro.2025.102468

Sakina Nemouchi , Sihem Salmi-Laouar , Ahmed Awad Abdelhady , Amor Deghaichia , Mostafa M. Sayed , Youssef Bazeen , Michael Hesemann , Mohamed Ahmed , Mabrouk Boughdiri

{"title":"Ostracod and foraminiferal assemblages in Tébessa (Northeast Algeria): Insights into Santonian cooling effects","authors":"Sakina Nemouchi , Sihem Salmi-Laouar , Ahmed Awad Abdelhady , Amor Deghaichia , Mostafa M. Sayed , Youssef Bazeen , Michael Hesemann , Mohamed Ahmed , Mabrouk Boughdiri","doi":"10.1016/j.marmicro.2025.102468","DOIUrl":"10.1016/j.marmicro.2025.102468","url":null,"abstract":"<div><div>A well-exposed Coniacian-Santonian stratigraphic section in the Bir Mokadam Mountains, west of Tébessa (Algeria), was investigated through biostratigraphic and paleoenvironmental analyses focusing on planktic foraminifera and ostracods, respectively. The studied interval encompasses deposits from the Essen Formation, consisting predominantly of clayey marls. A total of 318 samples were collected and examined, leading to the identification of 26 planktic foraminiferal species distributed across 11 genera. The Coniacian is characterized by the presence of the <em>Dicarinella primitiva</em> and <em>Marginotruncana sinuosa</em> biozones, whereas the Santonian is distinguished by <em>Sigalia carpatica, Dicarinella asymetrica</em>, and <em>Globotruncanita elevata</em> biozones. The quantitative analyses revealed significant differences between the Coniacian and Santonian stages. The Coniacian and the lower parts of the Santonian exhibit higher diversity, characterized by a greater abundance of smooth ostracods, keeled and globular foraminifera. In contrast, the upper part of the Santonian is marked by a notable decrease in diversity and an increase in dominance of the ostracods and the also the planktonic foraminifera, indicating a less balanced ecological structure. The decline in diversity is herein tentatively attributed to a climate cooling and/or bottom-water minor dysoxia. Notably, there is a negative relationship between ostracod and foraminiferal abundances, the cause of which remains unclear and requires further investigations.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"197 ","pages":"Article 102468"},"PeriodicalIF":1.5,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143847486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Are there marine sedimentary losses and transgressions in the Southeast Bohai Sea during MIS 2-MIS 3? 2- 3期渤海东南部是否存在海相沉积损失和海侵？

IF 1.5 4区地球科学

Marine Micropaleontology Pub Date : 2025-03-27 DOI: 10.1016/j.marmicro.2025.102461

Qingtong Wang , Gayan Bandara , Wenqin Jiang , Feifei Wang , Hongxian Chu , Meiling Yin , Chuanxiu Luo

{"title":"Are there marine sedimentary losses and transgressions in the Southeast Bohai Sea during MIS 2-MIS 3?","authors":"Qingtong Wang , Gayan Bandara , Wenqin Jiang , Feifei Wang , Hongxian Chu , Meiling Yin , Chuanxiu Luo","doi":"10.1016/j.marmicro.2025.102461","DOIUrl":"10.1016/j.marmicro.2025.102461","url":null,"abstract":"<div><div>Sedimentary architecture dominated by transgression–regression cycles in the shallow Bohai shelf region contains information about global sea-level, climate and local tectonics. However, previous studies of transgression–regression cycles in this region at orbital timescales that extend back to the early Pleistocene are sparse. In this study, we present an integrated sedimentological, paleontological study of a 32.49 m (93kyr BP) core (HZK02) recovered from the Bohai Sea, China, for which an AMS <sup>14</sup>C and five OSL dates-based age model is available. Compared with previous pollen study in the Bohai area, the results show that there were two significant transgressions that occur in MIS 5c, top part of MIS 2 and MIS 1, with abundant foraminifera from the near shore shallow sea of the continental shelf, corresponding with prevailing arboreal pollen dominated by <em>Pinus</em> and <em>Quercus</em>. While, terrestrial herbs such as <em>Artemisia</em> and Chenopodiaceae dominated during colder periods, such as MIS 4, MIS 5b, when sea levels dropped significantly, corresponding with a scarcity of foraminifera in terrestrial sediment layers from MIS 5b, MIS 5a, MIS 4, and MIS 3. We find that at depth of 8.18–6.10 m, with depth of only 2.08 m and very high sediment rate, the duration age last from 64,100 yr BP to 10,500 yr BP, which might indicate some missing part of the deposition of MIS 3 and MIS 2. The transgressions signal has been found in top part of MIS 2 sediment, hardly in MIS 3.</div></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"196 ","pages":"Article 102461"},"PeriodicalIF":1.5,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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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