REVUE DE MICROPALEONTOLOGIE最新文献

{"title":"Latentifistularia and other radiolarian species from the lower Smithian (Lower Triassic) Lang Son Formation, NE Vietnam","authors":"Osamu Takahashi ,&nbsp;Takumi Maekawa ,&nbsp;Paulian Dumitrica ,&nbsp;Phong Duc Nguyen ,&nbsp;Toshifumi Komatsu","doi":"10.1016/j.revmic.2022.100610","DOIUrl":"10.1016/j.revmic.2022.100610","url":null,"abstract":"<div><p><span><span><span>Well-preserved Early Triassic </span>radiolarians were recovered from lower Smithian (lower Olenekian) beds in NE Vietnam. The radiolarian assemblage consists only of Paleozoic </span>relict species of Latentifistularia and some entactinarians. Three latentifistularian species, </span><em>Ruzhencevispongus vietnamensis</em> nov. sp., <em>Tetragregnon chilangensis</em> nov. sp., and <em>Tetragregnon langsonensis</em><span> nov. sp., belonging to the families Ruzhencevispongidae Kozur and Tetratormentidae Nestell and Nestell are erected herein. The entactinarian family Triassothamnidae nov. fam. and one new genus and two new species of </span><em>Langsonsphaera pseudocubica</em> nov. gen. nov. sp. and <em>Stigmosphaerostylus amabilis</em> nov. sp. are also described. In this region, the Paleozoic-type radiolarian groups Latentifistularia and Entactinaria survived across the Permian–Triassic boundary and were present during the Induan–early Olenekian interval. Thus, in the eastern Tethyan seaway near the equator, the true extinction of some Paleozoic radiolarian groups took place at the middle of the Early Triassic, immediately after the Smithian, rather than during the Permian–Triassic crisis.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132211339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"What's in a name? Revision of Peneroplis turonicus Said and Kenawy, 1957 (benthic foraminifera), an inappropriately-named taxon from the Cenomanian of the southern Neotethys margin","authors":"Felix Schlagintweit ,&nbsp;Mohsen Yazdi-Moghadam","doi":"10.1016/j.revmic.2022.100612","DOIUrl":"10.1016/j.revmic.2022.100612","url":null,"abstract":"<div><p><em>Peneroplis turonicus</em><span><span> Said and Kenawy is a poorly known benthic foraminifer that was originally described based on isolated specimens from the </span>Upper Cretaceous<span> of Egypt. Specimens from the Cenomanian Sarvak Formation of Iran indicate the presence of a finely agglutinated test wall displaying a pseudo-keriothecal texture, therefore, excluding this taxon from the porcelaneous Miliolida, namely family Peneroplidae. Based on the test morphology, wall structure and foraminal features, the species is herein tentatively assigned to </span></span><em>Neodubrovnikella</em> Schlagintweit and Rashidi (order Loftusiida), with the new combination <em>Neodubrovnikella turonica</em> (Said and Kenawy). A critical literature review leads to the conclusion that <em>N. turonica</em> represents a southern Neotethys Cenomanian marker taxon reported so far from Italy, Slovenia, Croatia, Kosovo, Greece, Lebanon, Syria, Morocco, Egypt, Turkey, Iraq, and Iran. Therefore, <em>Neodubrovnikella</em><span> does not represent a Maastrichtian genus as previously assumed but is as old as Cenomanian, disappeared from the fossil record in the proximity of the Cenomanian-Turonian boundary and reappeared after a considerable gap and ghost range.</span></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131696908","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diversity of polycystine radiolarians in sediment traps from the Ionian, North Aegean and Cretan Seas: A preliminary account","authors":"Taniel Danelian ,&nbsp;Mathias Meunier ,&nbsp;Martin Tetard ,&nbsp;Elisavet Skampa ,&nbsp;Maria Triantaphyllou ,&nbsp;Spyros Stavrakakis ,&nbsp;Alexandra Gogou","doi":"10.1016/j.revmic.2022.100606","DOIUrl":"10.1016/j.revmic.2022.100606","url":null,"abstract":"<div><p><span>The presence and diversity of polycystine radiolarians<span><span> in the North-Eastern Mediterranean Sea is explored for the first time through the analysis of sinking particles obtained from sediment traps moored in three open marine sites. In total, thirty species are identified for which we provide appropriate references and illustrations to clarify the species concept followed in this study; 13 of the identified species are Spumellarians, 16 are Nassellarians and one is an Entactinarian. The highest diversity is recorded in the Ionian site, in which 23 species were observed during November 2014, with approximately as many Nassellarian species as Spumellarians; a large number of species are in common with the fauna reported from the </span>Adriatic Sea, off Dubrovnik, but interestingly, 16 others are not. The lowest levels of radiolarian diversity, with 3 to 4 species at best, were observed in the north Aegean and Cretan Sea sites. Our observations improve also the paleobiogeographic knowledge of two polycystine species, one of which (</span></span><em>Gonosphaera primordialis</em><span> Jørgensen) was known previously from the high latitudes of both the northern and southern hemisphere and the other (</span><em>Qiuripylolena chikuchik</em> Zhang and Suzuki) from the Pacific ocean.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122467260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-marine ostracods from the Late Jurassic–Early Cretaceous of Araripe, Jatobá and Tucano Norte basins, northeast Brazil Ostracodes non marins Jurassique Superieur–Cretace Inferieur des bassins d'Araripe, Jatobá et Tucano Norte, nord-est Bresil","authors":"Débora Soares Almeida-Lima ,&nbsp;Enelise Katia Piovesan ,&nbsp;Juliana Guzmán ,&nbsp;Daniele de Melo Mendes ,&nbsp;Virgínio Henrique de Miranda Lopes Neumann","doi":"10.1016/j.revmic.2022.100605","DOIUrl":"10.1016/j.revmic.2022.100605","url":null,"abstract":"<div><p><span>The Araripe, Jatobá and Tucano Norte basins, northeast Brazil, have an extensive fossil record. Among the groups found, are the ostracods<span>, which have great relevance for this region due to their significant occurrence and wide diversity during the Upper Jurassic–Lower Cretaceous. These basins contain the rift process record of the Gondwana breakup for the posterior installation of the South Atlantic Ocean, data reinforced by the correlated ostracod non-marine fauna with some African basins. This paper presents a detailed taxonomic and biostratigraphic study of the ostracod species recovered from outcrops from these three basins. A total of 29 species were identified, distributed in eight genera: </span></span><em>Theriosynoecum pricei, Theriosynoecum</em> sp. cf. <em>T.</em> sp. 6, <em>Cypridea acicularis, Cypridea ambigua, Cypridea indiennensis densipunctata, Cypridea sellata, Cypridea semilunaris, Cypridea vianai, Cypridea paraibensis, Cypridea</em> (<em>Morinina</em>?) <em>bibullata bibullata, Cypridea</em> (<em>Morinina</em>?) <em>bibullata tribullata, Cypridea</em> sp. cf. <em>C.</em> (<em>Morinina</em>?) <em>langei, Cypridea</em> sp. cf. <em>Cypridea miritiensis, Cypridea</em> sp. 1, <em>Paracypridea brasiliensis, Paracypridea quadrirugosa quadrirugosa, Paracypridea</em> ex. gr. <em>elegans, Salvadoriella redunca posterior, Reconcavona</em>? <em>jatobaensis, Reconcavona striata, Reconcavona striatula, Reconcavona swaini, Reconcavona</em> aff. <em>R.</em>? <em>polita, Reconcavona</em> sp. cf. <em>R. triebeli, Reconcavona</em> sp.1, <em>Reconcavona</em> sp.2, <em>Rhinocypris</em> sp.1, <em>Darwinula</em>? sp. cf. <em>D. oblonga, Alicenula</em> sp. cf. <em>Alicenula leguminella</em><span>. From the identification of these species, it was possible to infer a stratigraphic range from Tithonian<span> to Barremian, which corresponds to the local RT-001 to RT-007 biozones.</span></span></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123729067","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphological evolution of menardiform globorotalids at Western Pacific Warm Pool ODP Hole 806C (Ontong-Java Plateau) Evolution morphologique du groupe de Globorotalia menardii au Site ODP 806C (Ontong-Java Plateau, Pacifique tropical occidental)","authors":"Michael Knappertsbusch","doi":"10.1016/j.revmic.2022.100608","DOIUrl":"https://doi.org/10.1016/j.revmic.2022.100608","url":null,"abstract":"<div><p>The morphological evolution was investigated in the tropical Neogene planktonic foraminiferal lineage <em>Globorotalia menardii, G. limbata</em> and <em>G. multicamerata</em><span> during the past 8 million years at ODP Hole 806C (Ontong-Java Plateau, western equatorial Pacific). This research is an extension of several similar studies since 2007 from the Caribbean Sea, the tropical Atlantic and the Eastern Equatorial Pacific. The goal is to find empirical and quantitative confirmation for morphological speciation – splitting or phyletic gradualism or accelerated evolution – in planktonic foraminifera with the above lineage as model objects. The present study from ODP Hole 806C serves as a test to discriminate between these evolutionary scenarios.</span></p><p>In the western equatorial Pacific warm and stable environments prevailed back to Pliocene times, and potential influences of Northern Hemisphere Glaciation are thought to bear less severely on shell size evolution than in the Atlantic Ocean. A slow and gradual pattern of shell size increase is therefore expected in the western tropical Pacific, in contrast to the intermittent rapid menardiform shell size increase during periods of intensified formation of warm water eddies in the southern to tropical Atlantic.</p><p>For this study a total of 11,101 specimens from 37 stratigraphic levels extending over the past 8 million years were morphometrically investigated thanks to the <em>AMOR</em> robot for imaging and microfossil orientation. Of those, 6080 specimens comprise the <em>G. menardii–limbata-multicamerata</em> plexus. Special attention was given to trends of spiral height (δX) versus axial length (δY) in keel view, for which bivariate contour- and volume-density diagrams were constructed to visualize speciation and evolutionary trends.</p><p>The investigation at Hole 806C showed, that <em>G. menardii</em> evolved in a more gradual manner than in the Atlantic. Contour plots of δX versus δY reveal modest bimodality between 3.18 Ma – 2.55 Ma with a dominant branch consisting of smaller <em>G. menardii</em> (δX&lt;∼300 μm) persisting until the Late Quaternary, and a less dominant branch of larger <em>G. menardii</em> (δX&gt;∼300 μm) until 2.63 Ma. There is evidence for cladogenesis – splitting with subsequent morphological divergence in the Late Pliocene <em>G. menardii-limbata-multicamerata</em><span> lineage, and which may be linked to changes in the thermocline. Due to the general scarcity of </span><em>G. multicamerata</em> at Site 806, the divergence was less clearly expressed than originally expected. Up-section, bimodality vanished but <em>G. menardii</em> populations shifted towards extra large shells between 2.19-1.95 Ma.</p><p>The morphological evolution of Pacific menardiform globorotalids contrasts the one observed in the Atlantic. This inter-oceanic asymmetry may indicate possible long-distance dispersal of <em>G. menardii</em>, at least during intermittent phases<em>.</","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"137312540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early Pliocene ostracods from the Nocella River Mouth sedimentary succession (NW Sicily, Italy)","authors":"Francesco Sciuto ,&nbsp;Agatino Reitano","doi":"10.1016/j.revmic.2021.100530","DOIUrl":"10.1016/j.revmic.2021.100530","url":null,"abstract":"<div><p><span><span>In this article is analysed for the first time the ostracods<span> association from the Early Pliocene (MPL 3 Zone) sandy clayey silt outcropping, along the shore, to the left of the Nocella river mouth (Castellammare Gulf, NW Sicily). The ostracods association is abundant and well preserved and is referred to a not very deep </span></span>paleoenvironment<span> of the Continental Shelf. Some species, belonging to the genera </span></span><em>Cytherelloidea, Eucytherura, Pseudocytherura, Aurila, Pachycaudites, Tenedocythere, Capsacythere, Echinocythereis</em> have been identified, described and figured here for the first time.</p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114772547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Time-spatial boundaries of bioecozonations (planktonic foraminifera) in the latest Quaternary: a case study from the western South Atlantic","authors":"Jaime Yesid Suárez-Ibarra ,&nbsp;Sandro Monticelli Petró ,&nbsp;Cristiane Fraga Frozza ,&nbsp;Tiago Menezes Freire ,&nbsp;Rodrigo Da Costa Portilho-Ramos ,&nbsp;María Alejandra Gómez Pivel","doi":"10.1016/j.revmic.2021.100554","DOIUrl":"10.1016/j.revmic.2021.100554","url":null,"abstract":"<div><p>Planktonic foraminifera assemblages accurately record climate fluctuations that occurred during the Quaternary. These assemblage variations (frequently abundance changes) are widely used to establish bioecozones. Since climate variations are neither synchronous nor spatially homogenous, this paper assesses the application of the bioecozonations from the south Brazilian continental margin to its understudied southern extreme. To accomplish this purpose, census counts were made on core SAT-048A, retrieved from the continental slope of the southern extreme, and were compared to published records from the south Brazilian continental margin. According to the age model, the sediment core SAT-048A spans the last 42 kyr. The last reappearance of the <em>Globorotalia menardii</em> complex is dated for the first time in the Pelotas Basin at 8.5 ka, marking the biochronologic limit of bioecozones Y/Z. The last disappearance of <em>Pulleniatina</em> spp., marker of the sub-bioecozones Y2/Y1, is dated at 25.7 ka<em>,</em> showing an asynchronous characteristic already reported for the Caribbean and Equatorial Atlantic, meanwhile, its last reappearance, that marks the Y1B/Y1A limit, is dated at 15.5 ka, agreeing with previous studies. The Pleistocene/Holocene boundary can be recognized based on the Last Abundance Peak of the <em>Globorotalia truncatulinoides</em> dextral morphotype (<em>Gt</em>dLAP), also recognized in other cores of the south Brazilian continental margin.</p><p><strong>Resumé</strong></p><p>Les assemblages de foraminifères planctoniques ont enregistré avec précision les fluctuations climatiques qui se sont produites au cours du Quaternaire. Ces variations d'assemblages (souvent des changements d'abondance) sont largement utilisées pour établir des bioécozones. Puisque les variations climatiques ne sont ni synchrones ni spatialement homogènes, cet article évalue l'application des bioécozonations sur la marge continentale sud du Brésil jusqu’à son extrême sud, sous-étudié. Pour atteindre cet objectif, des comptages ont été effectués sur le carotte SAT-048A, prélevée sur le talus continental de l'extrême sud, et ont été comparés aux enregistrements publiés de la marge continentale sud du Brésil. Selon le modèle d'âge, la carotte de sédiments SAT-048A a enregistré les 42 derniers kyr. La dernière réapparition du complexe <em>Globorotalia menardii</em> est datée pour la première fois dans le Bassin de Pelotas à 8,5 ka, marquant la limite biochronologique des bioécozones Y/Z. La dernière disparition de <em>Pulleniatina</em> spp., marqueur des sous-bioécozones Y2/Y1, est datée à 25,7 ka, montrant une caractéristique asynchrone déjà signalée pour les Caraïbes et l'Atlantique équatorial, en attendant, sa dernière réapparition, qui marque la limite Y1B/Y1A, est datée de 15,5 ka, en accord avec les études précédentes. La limite Pléistocène/Holocène peut être reconnue sur la base du dernier pic d'abondance du morphotype dextral <em>Globorotalia t","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120867788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiolarian evidence for Middle Bathonian radiolarites in the Episkopi Formation (Ayios Photios Group, Mamonia Complex, SW Cyprus).","authors":"Antriani Varnava ,&nbsp;Taniel Danelian ,&nbsp;Sylvie Regnier ,&nbsp;Léa Devaere","doi":"10.1016/j.revmic.2021.100549","DOIUrl":"10.1016/j.revmic.2021.100549","url":null,"abstract":"<div><p><span><span>The Ayios Photios Group in SW Cyprus represents a deep-water slope or base of slope sequence that was accumulated on a Mesozoic margin of the Mediterranean Tethys. The Episkopi Formation is an essentially radiolaritic sequence, the age of which was previously considered to range between the </span>Callovian<span><span> and the Valanginian<span>. A moderately well preserved (PI 4-5) radiolarian assemblage was extracted after laboratory leaching with diluted </span></span>hydrofluoric acid<span> of a radiolarian chert bed south of the village of Episkopi. Based on the co-occurrence of </span></span></span><em>Bernoullius rectispinus leporinus</em> Conti &amp; Marcucci, <em>Hexasaturnalis tetraspinus</em> (Yao) and <em>Theocapsommella cucurbiformis</em><span> (Baumgartner), the assemblage is correlated with the Middle Bathonian<span> (Unitary Association Zone 6). Our results extend downwards the known age range of radiolarites of the Episkopi formation and reduce the previously known range of depositional hiatus with the underlying Upper Triassic formations of the Ayios Photios Group.</span></span></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126598708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Additional taxonomic data on late Messinian ostracods from Eastern Tunisia","authors":"Francesco Sciuto ,&nbsp;Rim Temani ,&nbsp;Hayet Khayati Ammar","doi":"10.1016/j.revmic.2021.100604","DOIUrl":"10.1016/j.revmic.2021.100604","url":null,"abstract":"<div><p><span>The ostracod<span> fauna of two late Messinian stratigraphic sections in eastern Tunisia have been analysed. The first section (Salakta-SAL section), is located south of Cape Bon, the second (Wadi el Kebir–OK section) in the Sahel region. In both sections the shallow marine ostracod fauna is dominant but have also been found taxa referable to the Lago Mare facies. From the shallow water marine levels, several ostracods taxa were recognized; some of which, due to their morphological particularities, have been described as new species. In a first contribution (Sciuto </span></span><em>et al</em>., 2021) have been described twenty-four taxa. Now, a second series of sixty shallow water marine ostracod taxa coming from the sedimentary levels of the Oued El Bir Formation, considered unknown or little known until now are systematically listed below, described and illustrated. They belong to the genera <em>Cytherella, Bairdia, Cushmanidea, Cytheridea, Cyamocytheridea, Miocyprideis, Aurila, Cimbaurila, Peteraurila, Urocythere, Callistocythere</em>, <em>Leptocythere, Mediocytherideis</em>, <em>Loxoconcha, Loxoconchissa, Sagmatocythere, Neomonoceratina, Carinocythereis, Chrysocythere, Cistacythereis, Keijella, Mutilus, Neocytheretta, Okadaleberis, Verrucocythereis, Cytheretta, Xestoleberis.</em></p></div>","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114241220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Benthic foraminiferal morphogroups of Middle to Late Jurassic succession of Jhurio Dome, Kutch, Gujarat, India: Palaeoenvironmental implications","authors":"Ainul H. Ansari ,&nbsp;Abu Talib ,&nbsp;Avneet Kumar","doi":"10.1016/j.revmic.2021.100555","DOIUrl":"10.1016/j.revmic.2021.100555","url":null,"abstract":"<div><p>The analysis of the benthic foraminiferal assemblages recovered from the Jurassic sequence exposed at Jhurio Dome, Kutch, reveals the presence of six types of major morphogroups, some of them subdivided into subgroups. Changes in benthic foraminiferal morphogroups, including life habitat (from epifaunal to deep infaunal) and nutritional behaviour (from herbivores to omnivores, suspension-feeders to bacterial scavengers and detritivores to primary weed fauna) are mainly influenced by fluctuations in nutrient flux, oxygen availability, salinity<span> and bathymetry and are reliable indicators to interpret palaeoenvironmental fluctuations during the deposition of the sediments.</span></p><p>The Middle to Upper Jurassic sequence of Jhurio Dome is subdivided into four palaeoecological intervals on the basis of benthic foraminiferal morphogroup associations. Deposition in Palaeoecological interval I commenced with a transgressive phase in the outer shelf region with normal salinity as well as high oxygen and nutrient availability. Palaeoecological interval II witnessed fluctuating hyposaline conditions, depleted oxygen and low nutrient availability in a regressive episode in the middle shelf environment. Palaeoecological interval III is considered to have been deposited in a transgressive phase in the deepest part of the outer shelf with high salinity, increased levels of oxygen and nutrient flux. Palaeoecological interval IV, representing the upper part of the studied sequence is characterised by normal salinity, decreased oxygen levels, and high nutrient influx in a regressive middle shelf environment. The morphogroup analysis shows that, during the deposition of the analysed stratigraphic intervals, the environmental conditions at the sediment depositional site did not remain stable as indicated by the fluctuating shoreline on a tectonically rather unstable oceanic shelf.</p><p><strong>Resumé</strong></p><p>L'analyse des assemblages de foraminifères benthiques récupérés sur la séquence jurassique affleurant à Jhurio Dome, Kutch révèle la présence de six types de morphogroupes majeurs, certains d'entre eux subdivisés en sous-groupes. Les changements dans les morphogroupes des foraminifères benthiques, y compris l'habitat de vie (de l'épifaune à l'endofaune profonde) et le comportement nutritionnel (des herbivores aux omnivores, des suspensivores aux charognards bactériens et des détritivores à la faune primaire herbivore) sont principalement influencés par les fluctuations du flux de nutriments, la disponibilité en oxygène, la salinité et bathymétrie et sont des indicateurs fiables pour interpréter les fluctuations paléoenvironnementales lors du dépôt des sédiments.</p><p>La séquence du Jurassique moyen à supérieur de Jhurio Dome est subdivisée en quatre intervalles paléoécologiques sur la base d'associations de morphogroupes de foraminifères benthiques. Le dépôt dans l'intervalle paléoécologique I a commencé par une phase transgressive dans ","PeriodicalId":45442,"journal":{"name":"REVUE DE MICROPALEONTOLOGIE","volume":null,"pages":null},"PeriodicalIF":0.9,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133717605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}