Marine Micropaleontology最新文献

{"title":"Humid climate phases on the Island of Rhodes (Greece) during the late Pliocene at times of sapropel formation","authors":"Daniela Eichner ,&nbsp;Gerhard Schmiedl ,&nbsp;Jürgen Titschack ,&nbsp;Malu Ferreira ,&nbsp;Maria Triantaphyllou ,&nbsp;Nils Andersen ,&nbsp;Yvonne Milker","doi":"10.1016/j.marmicro.2024.102341","DOIUrl":"10.1016/j.marmicro.2024.102341","url":null,"abstract":"<div><p>The Island of Rhodes, located in the Eastern Mediterranean Sea, is affected by an active convergent plate boundary. In this context, marine sediments of Plio-Pleistocene age have been uplifted and are outcropping along the eastern coast of Rhodes. These archives provide an excellent opportunity to unravel the hydrological and climatic changes of the region during the late Pliocene. Our results provide new evidence for a more humid climate and an increased precipitation on the island during times of Northern Hemisphere summer insolation maxima and related sapropel formation in the Mediterranean deep sea. The periodic occurrence of eutrophic conditions at the shelf and upper slope off Rhodes is indicated by the recurrent dominance of eutrophic indicator species (of the genera <em>Bolivina</em>, <em>Eubuliminella</em> and <em>Rectuvigerina</em>), simultaneously with a decline in diversity and oligotrophic indicator species. These conditions resulted from higher primary productivity, triggered by local effects, such as enhanced precipitation and river run-off, which consequently favors the appearance of eutrophic taxa. The ∆δ¹³C records of the epibenthic foraminifera <em>Cibicidoides pseudoungerianus</em> and the shallow infaunal species <em>Uvigerina peregrina</em> indicate a slight productivity decrease towards younger times.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"187 ","pages":"Article 102341"},"PeriodicalIF":1.9,"publicationDate":"2024-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377839824000112/pdfft?md5=f144cdb77c61f231b2a04405d884141b&pid=1-s2.0-S0377839824000112-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139517364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paleoecological and paleobiogeographic implications of a seagrass-indicating foralgal skeletal assemblage: Retracing the Burdigalian Quilon Limestone (Kerala Basin, SW India)","authors":"Suman Sarkar ,&nbsp;Yogesh Pal Singh ,&nbsp;Poonam Verma","doi":"10.1016/j.marmicro.2023.102330","DOIUrl":"https://doi.org/10.1016/j.marmicro.2023.102330","url":null,"abstract":"<div><p><span><span><span>Seagrasses are marine angiosperms documented in shallow-marine, soft bottom settings across the Cenozoic. They proliferated globally after their divergence from other alismatid monocots in the </span>late Cretaceous followed by an adaptation to the marine environment. Detailed evaluation of seagrasses in the geological archives is of utmost importance to understand their responses to climatic and environmental alterations in the deep time perspective. Here we examine the lower </span>Miocene Quilon Limestone from the Kerala Basin (southwest India) that encompasses a </span><em>Pseudotaberina</em>-<em>Halimeda</em> floatstone signalling a robust photozoan foralgal skeletal assemblage. This is characterized by the dominant soritid foraminifer <em>Pseudotaberina</em><span> and the calcareous green alga </span><em>Halimeda</em><span><span>, in association with other foraminifera and representatives from various biotic groups that indicate a tropical seagrass </span>paleoenvironment. Abundant soritids together with various bryopsidalean </span><em>Halimeda</em> species indicate light and temperature as the major ecological drivers regulating the Quilon Limestone seagrass paleocommunity during the early Miocene (Burdigalian). The spatio-temporal distribution patterns of <em>Halimeda</em> also indicate temperature as the most prominent ecological constraint determining its dispersal and evolution at multiple latitudes. A well illuminated substrate is envisaged to support the development and calcification of the <em>Halimeda</em><span> thalli. Abundance of K-strategist foraminifera with minor occurrence of suspension-feeding bryozoans and some gastropods, bivalves indicate a low-nutrient environment.</span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"187 ","pages":"Article 102330"},"PeriodicalIF":1.9,"publicationDate":"2024-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139503863","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}

{"title":"Calcareous nannoplankton response to middle-late Eocene climate and sea-level changes in the SW Neo-Tethys","authors":"Jihede Haj Messaoud ,&nbsp;Nicolas Thibault ,&nbsp;Mohammed H. Aljahdali ,&nbsp;Chokri Yaich ,&nbsp;Yang-Guang Gu","doi":"10.1016/j.marmicro.2023.102329","DOIUrl":"10.1016/j.marmicro.2023.102329","url":null,"abstract":"<div><p><span>We investigate the response of calcareous nannoplankton<span><span><span> to the middle-late Eocene transition in the SW Neo-Tethys and compare our data to published results from X-ray diffraction (XRD) analysis, element content from X-ray fluorescence (XRF) and the abundance of </span>microfossils in the coarse fractions of the sediment. The </span>nannofossil assemblage is mainly composed of </span></span><em>Reticulofenestra</em> spp. (avg. 44%), <em>Sphenolithus</em> spp. (avg. 20%), <em>Discoaste</em>r spp. (avg. 18%) and <em>Pontosphaera</em> spp. (avg. 10%). The Relative abundance of <em>Zygrhablithus bijugatus</em> and the <em>Chiasmolithus</em> ratio are used with the visual assessment to evaluate the preservation. The <em>Sphenolithus</em>-<em>Reticulofenestra</em><span> turnover occurred before the MECO at the Lutetian-Bartonian boundary. Besides the significant influence of an evolutionary gradient caused by the disappearance of numerous species of Sphenoliths, Discoasterids, and Coccolithaceae, and the first appearance of multiple species of reticulofenestrids, paleoenvironmental conditions imposed a significant impact on the calcareous nannofossil assemblages. The abundance of ostracods<span> and the planktic/benthic foraminifera ratio depict relative sea-level changes. The microfossil assemblages and the lithological composition of the sediments track paleoclimatic and paleoenvironmental changes across the Lutetian to Priabonian. Dry conditions marked the middle Lutetian, followed by increased variability in hydrolyzing conditions during the late Lutetian and early Bartonian. An eutrophic and restricted ecosystem with high fine-grained material input is suggested for the Priabonian.</span></span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"187 ","pages":"Article 102329"},"PeriodicalIF":1.9,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139464264","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}

{"title":"Two new ceratioid cornucavate dinoflagellate cysts from the Upper Cretaceous, Gulf of Suez, Egypt","authors":"Ali Soliman ,&nbsp;Hamid Slimani ,&nbsp;Somia Said","doi":"10.1016/j.marmicro.2024.102338","DOIUrl":"10.1016/j.marmicro.2024.102338","url":null,"abstract":"<div><p><span>Diverse and well-preserved assemblages of organic-walled dinoflagellate cysts have been recovered from the Matulla Formation (Coniacian – Santonian), Gulf of Suez, Egypt. Among the abundant dinoflagellate cyst assemblages, the new species </span><em>Odontochitina elbeialyi</em> sp. nov. and <em>Odontochitina ornata</em> sp. nov. (Family Ceratiaceae) are described. The two new species are unique by having a granulate periphragm and three prominent horns. The horns are truncated distally and devoid of striae, ridges and perforations. <em>Odontochitina elbeialyi</em><span> sp. nov. is characterized by a weakly expressed tabulation on the pericyst indicated by the occasional presence of sutural lines or low ridges indicating the cingulum (two transverse ridges), at plate boundaries. </span><em>Odontochitina ornata</em> sp. nov. differs from the former, particularly by its clear tabulation, which is corniform gonyaulacoid and more strongly expressed by sutural ridges, and by rare short (rudimentary) sutural (mostly gonal) nipple-like, to truncated processes. Based on the current material, <em>Odontochitina elbeialyi</em> sp. nov. and <em>Odontochitina ornata</em><span> sp. nov. have short stratigraphic ranges and may therefore be considered as stratigraphic markers for the late Santonian (Late Cretaceous). Their comparison with all formally published species of the genus </span><em>Odontochitina</em> is presented and discussed, and the associated relevant dinoflagellate cyst taxa are also indicated. The paleoenvironmental significance of the <em>Odontochitina elbeialyi</em> sp. nov. and <em>Odontochitina ornata</em> sp. nov. is discussed.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"187 ","pages":"Article 102338"},"PeriodicalIF":1.9,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139398314","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}

{"title":"Integrated biostratigraphy of Upper Cretaceous deposits from an exceptional continental vertebrate-bearing marine section (Transylvanian Basin, Romania) provides new constraints on the advent of ‘dwarf dinosaur’ faunas in Eastern Europe","authors":"R. Bălc ,&nbsp;R. Bindiu-Haitonic ,&nbsp;S.-A. Kövecsi ,&nbsp;M. Vremir ,&nbsp;M. Ducea ,&nbsp;Z. Csiki-Sava ,&nbsp;D. Ţabără ,&nbsp;Ș. Vasile","doi":"10.1016/j.marmicro.2023.102328","DOIUrl":"10.1016/j.marmicro.2023.102328","url":null,"abstract":"<div><p><span>The present paper outlines the results of a detailed study of calcareous nannofossils<span><span> and small foraminifera made on Campanian<span> marine deposits from the southwestern part of the Transylvanian Basin, Romania, part of the marine-to-continental transitional Petrești succession that yielded the oldest temporally well-constrained continental vertebrate remains in this area. These results are integrated with new and previously published palynostratigraphic information as well as with novel detrital zircon geochronometry data. All three groups of </span></span>fossils<span> (calcareous nannofossils, small foraminifera, and palynomorphs) convergently indicate an early to middle Late Campanian age for the marine part of the Petrești section. Based on detrital zircon analyses, the most likely maximum depositional age of the studied deposits is 76 ± 1.7 Ma, thus confirming the age supported by microfossil<span> assemblages. Palaeoenvironmental interpretation of the fossil assemblages<span> recovered from the marine part of the Petrești section suggests that despite their flysch-like facies, these beds were deposited in a continental shelf setting, under </span></span></span></span></span>suboxic conditions<span><span> and frequent fluctuations in nutrient supply to the seafloor, but quite stable environmental conditions within the water column. The synthesis of all currently available biostratigraphic and geochronologic data from the Petrești succession suggests a middle-late Late Campanian start for the expansion of the emergent land areas that made up the latest Cretaceous Hațeg Island, earlier than previously accepted dates (Maastrichtian) for this event. Furthermore, it documents the establishment of a diversified continental vertebrate faunal assemblage by the second half of the Late Campanian on these emergent lands while also providing further evidence for a later, post-Campanian arrival of certain iconic Hațeg Island dinosaur groups such as titanosaurs and hadrosauroids. Finally, our data show that kogaionid multituberculate mammals were already members of the earliest known Hațeg Island faunas, extending the fossil record of this group from the </span>Maastrichtian into the later part of the middle Late Campanian.</span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"187 ","pages":"Article 102328"},"PeriodicalIF":1.9,"publicationDate":"2024-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139374584","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}

{"title":"Foraminifera associated with macroalgae on tropical coastal sandstone reefs","authors":"Davy Barbosa Bérgamo ,&nbsp;David Holanda de Oliveira ,&nbsp;Edson Régis Tavares Pessoa Pinho de Vasconcelos ,&nbsp;Nykon Craveiro ,&nbsp;José Souto Rosa Filho","doi":"10.1016/j.marmicro.2023.102325","DOIUrl":"10.1016/j.marmicro.2023.102325","url":null,"abstract":"<div><p><span>While they are extremely abundant and ecologically important, the epiphytic foraminifera of tropical reefs are still poorly known. The present study describes the foraminiferal assemblages associated with macroalgae on tropical reefs of the Brazilian coast. Samples of four species of macroalgae, two foliose (</span><em>Padina antillarum</em> and <em>Ulva lactuca</em>) and two corticated (<em>Palisada perforata</em> and <em>Gelidiella acerosa</em>), were collected from intertidal sandstone reefs at Pina, Enseada dos Corais, and Toquinho (Northeastern Brazil). Overall, only 13.3% of the 708,754 foraminifera specimens were alive, belonging to 37 species, with dominance of <em>Rosalina anglica</em>. Most tests were hyaline-perforate and conical in shape, and most species were permanently or temporarily sessile. The majority of living foraminifera were attached to the surface of <em>Palisada</em> and <em>Gelidiella</em>, and no attached specimens were found in either <em>Padina</em> or <em>Ulva</em>. The species richness and abundance of the living foraminifera varied significantly among the macroalgae, occurring the high values in <em>P. perforata</em>. The assemblages varied significantly between the two species of corticated macroalgae, and between the corticated and foliose species, but not between the two foliose algae. Some of the specimens of <em>Glabratella</em> and <em>Rosalina</em> were reproducing, and had juveniles attached to the parental test. This is the first study to focus on the ecological interactions of the epiphytic foraminifera of the tropical southern Atlantic Ocean, and its results indicate that the characteristics of the epiphytic assemblages can be used as a proxy for the understanding of the structure and function of microbenthic communities on tropical reefs.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"186 ","pages":"Article 102325"},"PeriodicalIF":1.9,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139028059","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}

{"title":"Corrigendum to “An endemic conodont fauna of Darriwilian (Middle Ordovician) age from the Santa Gertrudis Formation, southwestern Gondwanan margin and its paleobiogeographic relationships” [Marine Micropalaeontology volume 181 (2023) 1–21/Article Number 102241]","authors":"Guillermo L. Albanesi ,&nbsp;C. Rubén Monaldi ,&nbsp;Christopher R. Barnes ,&nbsp;Fernando J. Zeballo ,&nbsp;Gladys Ortega","doi":"10.1016/j.marmicro.2023.102327","DOIUrl":"https://doi.org/10.1016/j.marmicro.2023.102327","url":null,"abstract":"","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"186 ","pages":"Article 102327"},"PeriodicalIF":1.9,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377839823001263/pdfft?md5=45389c5545cfad1618f6f0600450b5da&pid=1-s2.0-S0377839823001263-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139090117","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new methodology for foraminifera extraction from cemented calcareous shelf sediments","authors":"Anna Arrigoni,&nbsp;Werner E. Piller,&nbsp;Gerald Auer","doi":"10.1016/j.marmicro.2023.102324","DOIUrl":"10.1016/j.marmicro.2023.102324","url":null,"abstract":"<div><p><span>Choosing the most conservative technique to extract unequivocally identifiable foraminiferal tests is crucial to avoid biases in sedimentary sequence<span><span> dating and paleoenvironmental interpretations. However, for problematic samples containing heavily encrusted specimens, the concentration and isolation of microfossils might be challenging. In this work, we analyzed Early-Middle Pleistocene samples from the International Ocean Discovery Program (IODP) Site U1460, located on the southwestern Australian shelf platform, characterized by extensive early marine </span>diagenesis. At this site, foraminiferal preservation varies between the glacial and interglacial phases. In particular, tests are highly encrusted in samples representing sea-level lowstands of glacials while exhibiting better preservation in samples corresponding to interglacials. As the application of previously established, very conservative preparation techniques (e.g., sieving technique, soaking in H</span></span>₂O₂ solution and gentle sonication) did not produce satisfactory results, it was necessary to set up a new procedure for foraminifera isolation specifically for the cautious cleaning of cemented benthic and planktic foraminiferal tests. This new methodology combines the use of a freeze-dryer with repeated soakings in highly-diluted H₂O₂<span> solution to disaggregate the material. To evaluate the efficiency of our technique objectively, we considered the improvements obtained with our procedure on the worst-preserved samples of our record (corresponding to glacials) and the best-preserved (associated with interglacials). Despite being more time-consuming than other preparation techniques, this newly developed procedure produces excellent results in samples exhibiting a high level of encrustation for reliable quantitative studies and isotope analysis on foraminiferal assemblages. Our new methodology is highly conservative and thus preserving even delicate taxa.</span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"187 ","pages":"Article 102324"},"PeriodicalIF":1.9,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139067805","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}

{"title":"Biodiversity and evolutionary phases of Lochkovian (Lower Devonian) conodonts in the Pyrenees: A comparative study","authors":"José Ignacio Valenzuela-Ríos ,&nbsp;Jau-Chyn Liao","doi":"10.1016/j.marmicro.2023.102326","DOIUrl":"10.1016/j.marmicro.2023.102326","url":null,"abstract":"<div><p><span>This paper aims to evaluate the zone-by-zone changes in Lochkovian<span> conodont biodiversity in the Pyrenees region and compare the results with previous studies. Additionally, the paper seeks to identify evolutionary phases within the Lochkovian. We analyse the stratigraphic range data from eight classical Pyrenean Lochkovian sections. A total of 48 taxa at the species level, primarily confined to the Lochkovian, are included in the analysis. We employ both qualitative and quantitative approaches, including Clark's method for the conodont evolution index and Foote's parameters for measuring taxonomic diversity and rates. The zonal scheme employed in this study follows the global three-fold subdivision of the Lochkovian stage, with additional subdivisions based on local records. The zone-by-zone analysis of stratigraphically well-controlled successions contributes to our understanding of the conodont diversity dynamics in this region. The results are consistent with previous studies, but also highlight the unique aspects of the Pyrenean conodont record. Their highest diversity occurs in the middle Lochkovian within the </span></span><em>kutscheri</em>-<em>pandora</em><span> beta Zone, succeeded by an extinction event towards the end of this interval. Following a brief proliferation of species at the onset of the upper Lochkovian, another extinction event concludes this Stage. Results from all different rate measurements applied to Pyrenean Lochkovian conodonts are in disagreement with the prevailing perspective suggesting an escalation in the proportion of singletons and a concomitant decline in per-taxon rates with an increase in interval length. Comparative analysis of conodont records across various regions (Carnic Alps, Prague Synform, Central Nevada, and the Pyrenees) during the Lochkovian reveals significant differences in biodiversity, taxonomic composition, and zonal distribution.</span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"187 ","pages":"Article 102326"},"PeriodicalIF":1.9,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139072242","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}

{"title":"Origins and paleoclimatic and paleoceanographic significance of laminated sediments of middle Pleistocene age from the southern Bering Sea","authors":"Jonaotaro Onodera ,&nbsp;Alan E.S. Kemp ,&nbsp;Richard B. Pearce ,&nbsp;Keiji Horikawa ,&nbsp;Kozo Takahashi","doi":"10.1016/j.marmicro.2023.102323","DOIUrl":"10.1016/j.marmicro.2023.102323","url":null,"abstract":"<div><p>Laminated diatomaceous sediments occur intermittently in the Bering Sea over the past 5 million years. A varve (annually deposited) origin for the laminae has been suggested, but there is currently no consensus. Here, we report results of a study of two laminated intervals dating from ∼528 ka and ∼ 782 ka from IODP Site U1340 on the Bowers Ridge. We combine conventional micropaleontological methods with scanning electron microscope analysis that resolves the seasonal cycle of flux events recorded and demonstrates an annual origin for the laminae. Resting spores of <em>Chaetoceros</em> spp., and more rarely of <em>Thalassiosira antarctica</em> represent early spring blooms with the latter likely due to increased meltwater input. Diatom laminae containing concentrations of <em>Shionodiscus trifultus</em>, <em>Thalassiosira</em> spp., <em>Actinocyclus curvulatus</em>, and <em>Neodenticula seminae</em>, represent flux from the main spring-summer bloom episodes, with the latter indicating influx of seed populations from the North Pacific Alaskan Stream. Concentrations of <em>Coscinodiscus</em> spp. in the uppermost part of the diatom laminae represent “Fall Dump” sedimentation of these stratified-adapted diatoms in response to break down of summer stratification in autumn/early-winter storms. The lithogenic laminae represent mainly winter deposition and rare earth element analysis suggests provenance from the southern Bering Sea shelf and the Aleutian Arc. Productivity was high in the studied intervals with total mass fluxes around 5 times higher than modern values. Variation in lamina thickness and diatom composition contain periodicities of 2–8 years, as well as a bi-decadal variability likely related to influence of the Pacific Decadal Oscillation.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"186 ","pages":"Article 102323"},"PeriodicalIF":1.9,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0377839823001226/pdfft?md5=61d648afd2a9e5ec3ec40ecca98ceee3&pid=1-s2.0-S0377839823001226-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138682558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}