Marine Micropaleontology最新文献

{"title":"Constant shell density of hyaline large benthic foraminifers under thermal stress","authors":"Shunichi Kinoshita ,&nbsp;Azumi Kuroyanagi ,&nbsp;Hodaka Kawahata ,&nbsp;Kazuhiko Fujita ,&nbsp;Toyoho Ishimura ,&nbsp;Atsushi Suzuki ,&nbsp;Harumasa Kano ,&nbsp;Yoshimi Kubota ,&nbsp;Hiroshi Nishi","doi":"10.1016/j.marmicro.2023.102232","DOIUrl":"10.1016/j.marmicro.2023.102232","url":null,"abstract":"<div><p>Recently, increased concentrations of anthropogenic atmospheric CO₂<span><span> have caused ocean warming and acidification, leading to swift environmental alterations. In coral reef regions, bleaching and death of symbiotic calcifying organisms have been distressing. Generally, large benthic foraminifers (LBF), a principal symbiotic calcifying organisms in coral reefs, have gained popularity because thermal stress impedes their growth and ecological functions. Nevertheless, due to the complex nature of the shell structure, it is unclear whether indicators (shell volume, density, and size) influence the calcification rate. Micro X-ray computed </span>tomography (MicroCT) has been efficiently used to study these parameters on porcelaneous LBF; however, hyaline LBF remained largely unexplored. In this research, reproducing populations of LBF </span><em>Calcarina gaudichaudii</em> were grown asexually under six varying temperatures (19 °C–29 °C). They were then determined using MicroCT. Shell weight and volume is reduced under high and low thermal stress with an optimal water temperature of 26 °C. However, the density of the shell was sustained at a continual level. These outcomes indicate that <em>C. gaudichaudii</em> can sustain a continual shell density given circumstances of growth inhibition due to thermal stress.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"181 ","pages":"Article 102232"},"PeriodicalIF":1.9,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42158911","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 in temperate fjords strongly affected by glacial meltwater, Tierra del Fuego, South America","authors":"Sergei Korsun ,&nbsp;Olga Kniazeva ,&nbsp;Wojciech Majewski ,&nbsp;Maria Angelica Godoi ,&nbsp;Tatiana Hromic ,&nbsp;Marina Varfolomeeva ,&nbsp;Jan Pawlowski","doi":"10.1016/j.marmicro.2023.102248","DOIUrl":"10.1016/j.marmicro.2023.102248","url":null,"abstract":"<div><p><span><span>Chilean Patagonia is one of the few regions in the Southern Hemisphere where </span>tidewater glaciers<span> deliver torrential meltwater<span>. We sampled the Beagle Channel and five tributary fjords, with and without glaciers, to explore modern foraminifera of this little studied region. Surface sediments (mud, sand, pebbles, and shell debris) were collected at 45 stations from water depths 15 to 250 m, along with four short cores. The soft bottom recovered at 35 stations was analyzed for grain size, Loss-on-ignition reflecting content of organic matter, and Rose-Bengal-stained foraminifera. The benthic fauna consisted of 86 attached and free-living species. </span></span></span><em>Uvigerina bifurcata</em>, <em>Alveolophragmium orbiculatum</em>, <em>Ammobaculites americanus</em>, <em>Stainforthia fusiformis</em>, <em>Globobulimina notovata</em>, and <em>Nonionoides grateloupii</em> were dominant. As shown by downcore distribution, <em>U. bifurcata</em> and <em>A. orbiculatum</em> occupied epifaunal and <em>G. notovata</em> and <em>S. fusiformis</em><span> infaunal microhabitats. Distribution of the dominant foraminifera showed no clear pattern, with the exception of </span><em>S. fusiformis</em>, which formed a monospecific assemblage in sediments enriched with organic matter. Certain subdominant species, including <em>Cassidulinoides parkerianus, Pullenia subcarinata,</em> and <em>Cibicides fletcheri</em>, showed environmental affinity to more sandy sediments, whereas the assemblage from more muddy sediments had no inherent taxa. Foraminiferal standing crop in size fraction &gt;125 μm was mostly 100 to 500 specimens per 10 cm³ but dropped to &lt;1 specimen near glacier fronts, where foraminifera varied greatly between stations and did not constitute a single, unified assemblage. This patchy pattern seems to result from environmental instability caused by rapidly settling mineral fines and from random dispersal and activation of propagules. It helps to interpret records of other meltwater-dominated events.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"181 ","pages":"Article 102248"},"PeriodicalIF":1.9,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45828039","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":"Northward migration of the maximum Indian summer monsoon precipitation during the early–mid-Holocene: Evidence from sporopollen in the Andaman Sea","authors":"Zijie Yang ,&nbsp;Chuanxiu Luo ,&nbsp;G.M. Ariful Islam ,&nbsp;Xuhui Dong ,&nbsp;Xiang Su ,&nbsp;Rong Xiang ,&nbsp;Shuhuan Du ,&nbsp;Yiping Yang ,&nbsp;Shengfa Liu","doi":"10.1016/j.marmicro.2023.102230","DOIUrl":"10.1016/j.marmicro.2023.102230","url":null,"abstract":"<div><p>The Indian summer monsoon (ISM) significantly influences the evolution of the natural environment and the development of human societies in South Asia, however, the spatiotemporal nature of the maximum ISM precipitation remains uncertain. We present the first sedimentary sporopollen record from core ADM-C1 in the southern Andaman Sea, covering the past 11.2 ka to better understand the evolutionary history of the ISM. We use the percentage values of tropical–subtropical broad-leaved tree pollen to indicate regional precipitation. These pollens reached their highest abundances during ∼11–9 cal ka BP, indicating warmest and wettest climatic conditions in the southern Andaman Sea region. The subsequent retreat of the tropical–subtropical broad-leaved forest could reflect a gradual decline in ISM. By comparing numerous ISM precipitation records, we divided these records into two patterns: the timing of maximum ISM precipitation of Pattern 1 records during the early-Holocene (11–9 cal ka BP) and that of Pattern 2 records after 9 cal ka BP. The shift in the maximum ISM precipitation from Pattern 1 to Pattern 2 reflects a northward migration during the early–mid-Holocene, probably induced by the northward migration of the mean position of the Intertropical Convergence Zone (ITCZ). Furthermore, the ∼1.8 ka temporal lag between Patterns 1 and 2 could have resulted from the relatively weak Atlantic Meridional Overturning Circulation, which might have hindered the ITCZ from migrating northward before 9 cal ka BP.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"181 ","pages":"Article 102230"},"PeriodicalIF":1.9,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42923195","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":"Implication of size fraction on benthic foraminiferal-based paleo-reconstructions: A case study from the Bay of Biscay (NE Atlantic)","authors":"Pauline Depuydt ,&nbsp;Christine Barras ,&nbsp;Samuel Toucanne ,&nbsp;Eleonora Fossile ,&nbsp;Meryem Mojtahid","doi":"10.1016/j.marmicro.2023.102242","DOIUrl":"10.1016/j.marmicro.2023.102242","url":null,"abstract":"<div><p><span><span>Many paleoenvironmental studies based on benthic foraminiferal assemblages use different protocols for sample analysis. A standardized protocol has been recently established for biomonitoring applications, but for paleostudies, the influence of size fraction on benthic foraminiferal composition and biodiversity is poorly documented. We studied </span>fossil foraminiferal assemblages along two paleorecords (BOBGEO-CS05 and SU81–44) from the Bay of Biscay covering the last ∼35 ka cal BP. We investigated diversity and community composition to compare the impact of each size fraction (63-150 μm, &gt;150 μm, &gt;63 μm) on environmental interpretations. Foraminiferal diversity was affected by the accumulation of small opportunistic species. In terms of faunal composition, both paleorecords displayed a different pattern depending on the size fraction selected. While in both cores, the 63-150 μm fraction blurred the signal of some rare indicator species, our results show that i) in BOBGEO-CS05, it yielded no extra ecological information compared to the large fraction whereas ii) in SU81–44, it contained small opportunistic species that were not present in the &gt;150 μm, impacting therefore paleoenvironmental interpretations. According to these findings, we recommend: i) to focus on the large fraction for a thorough taxonomic determination and a detailed analysis of </span>benthic assemblages, and ii) to analyse the small fraction separately after a taxonomical identification of major species and strategic selection of studied samples. Although the 125 μm size limit was not tackled in this study, we recommend to use it for the limit between the small and large fractions instead of 150 μm for harmonization with the previously published standardized protocol for living faunas.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"181 ","pages":"Article 102242"},"PeriodicalIF":1.9,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46512286","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":"Benthic foraminiferal morphogroups and their response to relative sea-level changes in the upper Hauterivian-lower Barremian Agua de la Mula Member of the Agrio Formation (Patagonia, Argentina)","authors":"M. Caratelli ,&nbsp;F. Archuby","doi":"10.1016/j.marmicro.2023.102249","DOIUrl":"10.1016/j.marmicro.2023.102249","url":null,"abstract":"<div><p><span>A morphogroup analysis of the upper Hauterivian-lower Barremian<span><span> foraminiferal assemblages from the Agua de la Mula Member of the Agrio Formation (Neuquén Basin, Argentina) reveled six associations based on benthic foraminiferal morphogroups identified by means of cluster analysis and treated with multivariate methods. In order to assess the paleoenvironmental significance of the morphogroup associations, they were evaluated in relation to sampled geographic localities, ammonite biozones, sedimentary facies, and position into </span>depositional sequences of the five sections analyzed. For this purpose, the statistical techniques of RDA, partial-RDA, </span></span>PERMANOVA<span>, and PCoA were applied. The morphogroup associations MgFA1, MgFA4, MgFA5 and MgFA6 revealed high percentages of planoconvex, biconvex and conical forms, with an inferred epifaunal habit and active herbivorous feeding strategy. The remaining MgFAs2 and 3 are mainly represented by planispiral tests with lenticular, flattened and elongated forms, attributed to shallow infaunal lifestyle and detrital and bacterial scavenger feeding habit. Sedimentation rates and associated food availability were considered the main controlling factors in the distribution of morphogroups across the analyzed tract of the basin, revealing differences between proximal and distal sectors. In the sections characterized by higher terrigenous input, in a most proximal position of the basin, food increases downward in the sediments and so shallow infaunal morphogroups prevail (MgFAs2–3). At the same time, shallow infaunal-dominated associations are distributed throughout 3rd-order regressive systems tracts that commonly are associated with high sedimentation rates. Associations mostly represented by epifaunal morphogroups (MgFAs1, 4–6) recur at 3rd-order transgressive systems tracts where low sedimentary input characterizes the sequences, favoring long exposure of organic matter at the seafloor. Moreover, epifaunal forms with grazing herbivorous and detritivorous habits increase throughout the distal sector of the basin, following the decreasing supply of organic matter in settings farther from sedimentary input.</span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"181 ","pages":"Article 102249"},"PeriodicalIF":1.9,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49183291","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":"Middle Miocene final demise of remnants of an eastern Neotethyan seaway, Naga Hills, Indo-Myanmar Range","authors":"Kapesa Lokho ,&nbsp;Jonathan C. Aitchison ,&nbsp;Ankit Kumar ,&nbsp;Renjie Zhou ,&nbsp;Muthusamy Prakasam ,&nbsp;D.S.N. Raju","doi":"10.1016/j.marmicro.2023.102243","DOIUrl":"10.1016/j.marmicro.2023.102243","url":null,"abstract":"<div><p><span>Miocene<span><span> planktonic foraminifers occur in shale intercalated with thinly bedded siltstone and sandstone of the Surma Group in the foothills of the Naga Schuppen Belt of the Indo-Myanmar Range. Fourteen species from eleven genera are the first clearly imaged middle Miocene foraminifers recorded from the Surma Group in the Naga Hills. This new M5-M6 assemblage from the upper unit of the Bhuban Formation correlates to the uppermost </span>Burdigalian<span> to Langhian (16–14 Ma). Biostratigraphy, </span></span></span>paleoenvironment<span><span> and paleogeography<span> of the assemblage are all significant. They provide a basis for widespread regional and global correlation constraining the timing of elimination of the final remnants of the Neotethyan seaway between India and eastern Eurasia. Results indicate that, unlike the western and Tibetan </span></span>Himalayas<span> where similar seaways disappeared before the Miocene, a shallow marine embayment that connected to the Indian Ocean endured in eastern parts of the India-Eurasia collision zone until the Middle Miocene.</span></span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"181 ","pages":"Article 102243"},"PeriodicalIF":1.9,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48881154","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":"Early Cretaceous monsoonal upwelling along the northern margin of the Gondwana continent: Evidence from radiolarian cherts","authors":"Xiaohui Cui ,&nbsp;Xin Li ,&nbsp;Jonathan C. Aitchison ,&nbsp;Hui Luo","doi":"10.1016/j.marmicro.2023.102247","DOIUrl":"10.1016/j.marmicro.2023.102247","url":null,"abstract":"<div><p><span><span>Radiolarian-bearing cherts are widely exposed in the volcanic-sedimentary sequences associated with the Purang ophiolitic mélange in the western segment of the Yarlung Tsangpo suture zone. Highly diverse and well preserved </span>Lower Cretaceous (Valanginian–Hauterivian) radiolarian assemblages that correlate to the </span><em>Cecrops septemporatus</em> Zone occur in bedded cherts in the Peiersanggangmu section of the southern Purang ophiolitic mélange. Fifty-five species belonging to 38 genera, including characteristic species: <em>Archaeodictyomitra apiarium</em> (Rüst), <em>Cecrops septemporatus</em> (Parona), <em>Hemicryptocapsa capita</em> Tan, <em>Pseudodictyomitra carpatica</em> (Lozyniak), and <em>Svinitzium pseudopuga</em> Dumitrica, have been recognized.</p><p><span>Geochemistry of the cherts reveals high SiO</span>₂ contents (average: 92.23 wt%), Al/(Al + Fe + Mn) ratios, and low La_N/Ce_N<span> ratios. Post Archean Australian Shale (PAAS) normalized rare earth element<span> (REE) abundance patterns exhibit moderately positive Ce anomalies (mean Ce/Ce* =1.35) with relative enrichment in light rare earth elements (LREEs). These features are indicative of deposition in an oceanic basin close to a continental margin environment. Lithological characteristics and geochemical results suggest that the paleogeographical location for these radiolarian-bearing bedded cherts closely matches northern regions of the Indian continent, where existed enhanced upwelling activity and surface mixing resulting from monsoon activities.</span></span></p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"181 ","pages":"Article 102247"},"PeriodicalIF":1.9,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42095957","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":"New paleocene calcareous nannofossils: Carlamuelleria, Davidbukrya, Mauriceblackia, Noelia and Senelia","authors":"Osman Varol","doi":"10.1016/j.marmicro.2023.102220","DOIUrl":"https://doi.org/10.1016/j.marmicro.2023.102220","url":null,"abstract":"<div><p><span><span>Selected Paleocene calcareous nannofossils<span> were studied using mobile mounts, allowing analysis of their structural units, optical properties, and the establishment of a new family; Carlamuelleraceae and five </span></span>new genera; </span><em>Carlamuelleria, Davidbukrya, Mauriceblackia, Noelia,</em> and <em>Senelia</em>. The following twelve new species; <em>Carlamuelleria karacuhae, Carlamuelleria katapliktikos, Carlamuelleria tuezueniorum, Davidbukrya claracirculus, Davidbukrya clemencesalleyae, Davidbukrya perchnielseniae, Discoaster bordii, Noelia kolona, Noelia mahaniae, Noelia uenverdii, Senelia perifanos</em> and <em>Senelia plevrotos</em> are also described. Three new combinations are introduced: <em>Carlamuelleria bramlettei</em>, <em>Davidbukrya perpolitus</em> and <em>Mauriceblackia media.</em> The stratigraphic ranges of the new species and their speculative evolutionary trends are presented.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"180 ","pages":"Article 102220"},"PeriodicalIF":1.9,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49726083","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":"Organic-walled dinoflagellate cyst assemblages in surface sediments of the Ría de Vigo (Atlantic margin of NW Iberia) in relation to environmental gradients","authors":"Iria García-Moreiras ,&nbsp;Sarai Vila Costas ,&nbsp;Soledad García-Gil ,&nbsp;Castor Muñoz Sobrino","doi":"10.1016/j.marmicro.2023.102217","DOIUrl":"10.1016/j.marmicro.2023.102217","url":null,"abstract":"<div><p>Organic-walled dinoflagellate cyst assemblages were analysed in 31 surface sediment samples from the Ría de Vigo (NW Iberia) to obtain supporting evidence for the interpretation of past environmental signals from sediment cores. Complementarily, the totals of pollen (and pollen from riparian taxa), foraminiferal linings and freshwater algae were also considered to test their value as (palaeo)environmental indicators in fluvio-marine sedimentary environments. Abundances of foraminiferal linings gradually increased towards the ría's mouth, which supports its use as a proxy to infer the degree of marine influence in the sediment record. The ratio of dinoflagellate cysts to pollen and spores (D/P) increased with distance to the main river's mouth (and water depth) in the inner (&lt; 7 m water depth) and the outer (&gt; 20 m) parts of the ría. Total pollen concentrations decreased with water depth in the outer part but did not show any clear trend in the rest of the ría. No clear pattern in the distributions of pollen from riparian plants and spores from freshwater microalgae was detected. Multivariate analyses (clustering and RDA) performed on dinoflagellate cyst records and environmental data reflected a marked inshore-offshore distribution pattern mainly controlled by a fluvio-marine environmental gradient. Increasing abundances of cysts of <em>Gymnodinium</em> species and heterotrophic cysts as well as higher cyst diversity characterised the deeper environments of the outer ría. These observations suggest a relationship with increased shelf influence and are compatible with the heterotroph upwelling signal described in previous works. A very different cyst association with a predominance of autotrophic cysts characterised the intermediate and inner parts of ría, where exceptionally high cyst abundances of <em>Lingulodinium polyedra</em> (∼ 56–99% and ∼ 200–114,000 cysts.g⁻¹) were reported. Abundances of cysts of <em>L. polyedra</em> positively correlated with shallower and higher river-influenced environments characterised by higher sea-surface temperature. Our results agree with previous studies and reinforce the value of this species as an indicator of warmer and stratified conditions. Moreover, cysts of <em>L. polyedra</em> positively correlated with winter sea-surface nitrate contents, which is compatible with the nutrient enrichment signal (natural or anthropogenic) that has already been described in other deep and stratified estuarine environments and is consistent with historical cyst records obtained in the Ría de Vigo. However, further research is needed to disentangle the nutrient enrichment signal from the influence of other environmental factors.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"180 ","pages":"Article 102217"},"PeriodicalIF":1.9,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41812765","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":"Extraction of calcareous dacryoconarid microfossils from limestones and mudrocks by surfactants paired with freeze-thaw processing","authors":"Ashley N. Prow ,&nbsp;Zunli Lu ,&nbsp;Amy B. Frappier ,&nbsp;Lucy E. Weisbeck ,&nbsp;Caroline R. Underwood","doi":"10.1016/j.marmicro.2023.102216","DOIUrl":"10.1016/j.marmicro.2023.102216","url":null,"abstract":"<div><p><span><span>Microfossils<span> offer a wealth of paleoenvironmental information, but their extraction from consolidated material, especially ancient rocks, is time-consuming and often lacks systematic methodological development. This study examined the efficacy of repeated freeze-thaw processing paired with different surfactants (anionic, cationic, and detergent) on the extraction of fossils from the order Dacryoconarida, conically shaped calcareous microfossils that occur in diverse marine facies of the </span></span>Devonian Period. A stepwise technique was developed involving saturation of rocks in either 18 Ω water or 25% NaCl, followed by freezing and then boiling in surfactant (Pinequat, Decon 90, or Calgon in Na</span>₂CO₃ solution). In comparison with saturation in NaCl solution, saturation in water generally had higher yields of disaggregated material and more intact fossils. All surfactants performed better at extraction compared to boiling in pure water. Across all lithologies examined, Na₂CO₃-buffered Calgon (sodium hexametaphosphate) disaggregated rock most efficiently, but Na₂CO₃ solution alone generally had the highest yield of total and intact fossil specimens. Pinequat, a cationic surfactant, yielded more disaggregate for siliclastic samples compared to calcareous samples, but had lower fossil yield. Decon 90, an anionic surfactant, performed better at disaggregating limestones and had higher fossil extraction efficiency than Pinequat across all lithologies. Freeze-thaw processing pairing water saturation and 5% Na₂CO₃ simmering is an effective treatment for the disaggregation of rocks to extract analytically viable amounts of dacryoconarids from fossiliferous samples. This pairing had greater fossil extraction potential than surfactants at the concentrations tested in this study and is recommended if the elemental composition of the target rocks is unconstrained.</p></div>","PeriodicalId":49881,"journal":{"name":"Marine Micropaleontology","volume":"180 ","pages":"Article 102216"},"PeriodicalIF":1.9,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49564357","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}