We discriminated Bashkirian to Moscovian (Pennsylvanian) conodont faunas including 19 species of nine genera from the Omi Limestone in the Akiyoshi Terrane and established the following four conodont zones in ascending order, the Declinognathodus noduliferus, Neognathodus symmetricus-Idiognathoides sulcatus sulcatus, "Streptognathodus" expansus, and Mesogondolella clarki Zones. These conodont zones are correlated locally and internationally. The Bashkirian/Moscovian boundary horizon is probably located at the upper part of the "S."s expansus Zone. We further systematically treated obtained conodont species, herein.
{"title":"Bashkirian-Moscovian (Pennsylvanian) conodonts from the pelagic atoll carbonate of the Omi Limestone, Akiyoshi Terrane, central Japan","authors":"Yui Takahashi, Sachiko Agematsu, K. Sashida","doi":"10.47894/mpal.66.4.06","DOIUrl":"https://doi.org/10.47894/mpal.66.4.06","url":null,"abstract":"We discriminated Bashkirian to Moscovian (Pennsylvanian) conodont faunas including 19 species of nine genera from the Omi Limestone in the Akiyoshi Terrane and established the following four conodont zones in ascending order, the Declinognathodus noduliferus, Neognathodus symmetricus-Idiognathoides sulcatus sulcatus, \"Streptognathodus\" expansus, and Mesogondolella clarki Zones. These conodont zones are correlated locally and internationally. The Bashkirian/Moscovian boundary horizon is probably located at the upper part of the \"S.\"s expansus Zone. We further systematically treated obtained conodont species, herein.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70444450","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}
The larger benthic foraminifera (LBF) assemblage from shallow hypersaline coastal ponds located in the intertidal area of theUnitedArab EmirateWestern Region was investigated. The studied coastal ponds are located between a lagoonal areawith carbonate sedimentation, and a supratidal, evaporite-dominated, sabkha. Epiphytic larger benthic foraminifera, mostly belonging to the genus Peneroplis, dominate the benthic foraminifera assemblage. At all the sampled locations, the larger benthic foraminifera assemblage is characterised by high percentages of tests with abnormal growth. Dissolution and microboring are also common on the majority of LBF tests. The high percentage of abnormal tests reflects natural environmental stress caused by the instability of physical parameters (particularly high and variable salinity and temperature) in this transitional marine environment. The unique presence of epiphytic species in some of the ponds suggests that epiphytic foraminifera are transported into the ponds attached to floating seagrass and subsequently continue to live in the stressed pond environment.
{"title":"Abnormal test growth in Larger Benthic Foraminifera from hypersaline coastal ponds of the United Arab Emirates","authors":"Flavia Fiorini, S. Lokier","doi":"10.47894/mpal.66.2.06","DOIUrl":"https://doi.org/10.47894/mpal.66.2.06","url":null,"abstract":"The larger benthic foraminifera (LBF) assemblage from shallow hypersaline coastal ponds located in the intertidal area of theUnitedArab EmirateWestern Region was investigated. The studied coastal ponds are located between a lagoonal areawith carbonate sedimentation, and a supratidal, evaporite-dominated, sabkha. Epiphytic larger benthic foraminifera, mostly belonging to the genus Peneroplis, dominate the benthic foraminifera assemblage. At all the sampled locations, the larger benthic foraminifera assemblage is characterised by high percentages of tests with abnormal growth. Dissolution and microboring are also common on the majority of LBF tests. The high percentage of abnormal tests reflects natural environmental stress caused by the instability of physical parameters (particularly high and variable salinity and temperature) in this transitional marine environment. The unique presence of epiphytic species in some of the ponds suggests that epiphytic foraminifera are transported into the ponds attached to floating seagrass and subsequently continue to live in the stressed pond environment.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70444366","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}
Taxonomy of fossil coccolithophores is based primarily on the heterococcolith life cycle stagemorphology and, at species level, on fine variations in size and shape. Coccolith size is relevant on routine identification of certain calcareous nannofossil species, but morphometry can also be a tool to study their morphological plasticity. Here we used a new morphometric statistical method to reassess Coccolithus pelagicus s. l. data from the Holocene of the west coast of Iberia. Our results suggest that both C. pelagicus subsp. braarudii and C. pelagicus subsp. pelagicus present morphological plasticity in response to (paleo)environmental changes, mainly variations in the upwelling regime in the west coast of Portugal and (paleo)oceanographic conditions in the North Atlantic linked to glacial periods of the Holocene.
{"title":"Coccolithus pelagicus subsp. braarudii morphological plasticity as a response to variations in the upwelling regime of the west coast of Iberia","authors":"Gonçalo Prista, Á. Narciso, M. Cachão","doi":"10.47894/mpal.66.6.06","DOIUrl":"https://doi.org/10.47894/mpal.66.6.06","url":null,"abstract":"Taxonomy of fossil coccolithophores is based primarily on the heterococcolith life cycle stagemorphology and, at species level, on fine variations in size and shape. Coccolith size is relevant on routine identification of certain calcareous nannofossil species, but morphometry can also be a tool to study their morphological plasticity. Here we used a new morphometric statistical method to reassess Coccolithus pelagicus s. l. data from the Holocene of the west coast of Iberia. Our results suggest that both C. pelagicus subsp. braarudii and C. pelagicus subsp. pelagicus present morphological plasticity in response to (paleo)environmental changes, mainly variations in the upwelling regime in the west coast of Portugal and (paleo)oceanographic conditions in the North Atlantic linked to glacial periods of the Holocene.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70444967","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}
Roadian radiolarians are described from strata exposed in a small quarry (Quarry section) on U.S. Highway 62/180 located 3 km northeast of its junction with Texas Highway 54, Culberson County, Guadalupe Mountains, West Texas. These strata were long considered as Bone Spring Limestone of Leonardian (Early Permian) in age, but in recent years have been assigned to the Williams Ranch Member of the Cutoff Formation of the Roadian Stage (Guadalupian, middle Permian) based on the presence of the ammonoid species Paraceltites elegans. Radiolarians are of excellent preservation and the fauna is very diverse with 29 species of 11 genera described belonging to orders Albaillellaria and Entactinaria.Among them, 15 new species and one new genus, Apachevella, have been described, and five species emended. New species are Campanulithus cutoffi, Albaillella exilis, Pseudoalbaillella pseudoscalprata, P. japonica, P. laevis, Entactinia siciformis, E. longiacus, E. rezedae, Trilonche belli, Entactinosphaera texana, Polyedroentactinia macilenta, P. cancellata, P. porosa, P. bifida, and Kashiwara roadensis. Emended species are Pseudoalbaillella cona Cornell and Simpson, Entactinia parapycnoclada Nazarov and Ormiston, Trilonche tyrrelli (Nazarov and Ormiston), Apachevella capitanensis (Nestell and Nestell), and Wuyia endocarpa (Nazarov and Ormiston). Conodonts are represented by Jinogondolella nankingensis (Jin) with its three subspecies, J. nankingensis nankingensis (Jin), J. nankingensis behnkeni Wardlaw and Nestell and J. nankingensis tenuis Wardlaw, and elements of Sweetina and Hindeodus wordensis Wardlaw.
公路放射虫是在美国62/180高速公路上的一个小采石场(采石场段)的地层中发现的，该高速公路位于德克萨斯州西部瓜达卢佩山脉Culberson县与德克萨斯州54号高速公路交界处东北3公里处。这些地层在年代上一直被认为是Leonardian(早二叠世)的骨泉灰岩，但近年来根据类氨物种Paraceltites elegans的存在，被划分为Roadian阶段(中二叠世瓜达鲁普期)切断组Williams Ranch段。放射虫保存状况良好，区系十分多样，共分属Albaillellaria目和Entactinaria目11属29种。其中，发现了15个新种和1个新属(Apachevella)，修正了5个种。新物种是Campanulithus cutoffi, Albaillella exilis, Pseudoalbaillella pseudoscalprata, p .粳稻,p .光滑的Entactinia siciformis, e . longiacus e . rezedae Trilonche瑞塔,Entactinosphaera texana, Polyedroentactinia macilenta, p . cancellata p . porosa p .裂,Kashiwara roadensis。修正种为Pseudoalbaillella cona Cornell和Simpson、Entactinia parapycnoclada Nazarov和Ormiston、Trilonche tyrrelli (Nazarov和Ormiston)、Apachevella capitanensis (Nestell和Nestell)和Wuyia endocarpa (Nazarov和Ormiston)。牙形刺以Jinogondolella nankingensis (Jin)及其3个亚种J. nankingensis nankingensis (Jin)、J. nankingensis behnkeni Wardlaw、Nestell和J. nankingensis tenuis Wardlaw以及Sweetina和hinindeodus wordensis Wardlaw为代表。
{"title":"Roadian (earliest Guadalupian, Middle Permian) Radiolarians from the Guadalupe Mountains,West Texas, USA Part I: Albaillellaria and Entactinaria","authors":"G. Nestell, M. Nestell","doi":"10.47894/mpal.66.1.01","DOIUrl":"https://doi.org/10.47894/mpal.66.1.01","url":null,"abstract":"Roadian radiolarians are described from strata exposed in a small quarry (Quarry section) on U.S. Highway 62/180 located 3 km northeast of its junction with Texas Highway 54, Culberson County, Guadalupe Mountains, West Texas. These strata were long considered as Bone Spring Limestone of Leonardian (Early Permian) in age, but in recent years have been assigned to the Williams Ranch Member of the Cutoff Formation of the Roadian Stage (Guadalupian, middle Permian) based on the presence of the ammonoid species Paraceltites elegans. Radiolarians are of excellent preservation and the fauna is very diverse with 29 species of 11 genera described belonging to orders Albaillellaria and Entactinaria.Among them, 15 new species and one new genus, Apachevella, have been described, and five species emended. New species are Campanulithus cutoffi, Albaillella exilis, Pseudoalbaillella pseudoscalprata, P. japonica, P. laevis, Entactinia siciformis, E. longiacus, E. rezedae, Trilonche belli, Entactinosphaera texana, Polyedroentactinia macilenta, P. cancellata, P. porosa, P. bifida, and Kashiwara roadensis. Emended species are Pseudoalbaillella cona Cornell and Simpson, Entactinia parapycnoclada Nazarov and Ormiston, Trilonche tyrrelli (Nazarov and Ormiston), Apachevella capitanensis (Nestell and Nestell), and Wuyia endocarpa (Nazarov and Ormiston). Conodonts are represented by Jinogondolella nankingensis (Jin) with its three subspecies, J. nankingensis nankingensis (Jin), J. nankingensis behnkeni Wardlaw and Nestell and J. nankingensis tenuis Wardlaw, and elements of Sweetina and Hindeodus wordensis Wardlaw.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"14 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70443984","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}
In the present study from the late Pliocene of Neill West Coast Formation, Neil Island, serpulid tubes assignable to Ditrupa gracillima Grube have been identified with the help of tube morphological (light microscopy) and ultrastructural (SEM) studies. This is the first record of the species from the late Pliocene of India. The outer layer of D. gracillima is entirely different from other invertebrates, and the presence of Ridged Prismatic Structure (RRP) exclusively characterises this particular species. The mineralogical analysis (Raman spectroscopy and EDS) reveals a Mg-Ca skeletal for D. gracillima. Isotopic analysis indicates that there is a narrow range of variation in the delta 18 O values of D. gracillima The delta 13 C of D. gracillima shows significant variation and displays the most 13 C depleted values. Based on isotopic analysis it has been inferred that the deposition of sediments took place in a shallow marine environment and D. gracillima thrived in the proximity of hydrocarbon seepages. The present day distributional pattern of D. gracillima indicates that they are mainly confined in the Indo-Pacific region.
{"title":"First record of Ditrupa gracillima (Annelida, Polychaeta) from the late Pliocene of Andaman and Nicobar Basin: insights on the ultrastructure, stable isotopic signature and distribution pattern","authors":"A. Chakraborty, Amit K. Ghosh, Shailesh Agrawal","doi":"10.47894/mpal.66.6.02","DOIUrl":"https://doi.org/10.47894/mpal.66.6.02","url":null,"abstract":"In the present study from the late Pliocene of Neill West Coast Formation, Neil Island, serpulid tubes assignable to Ditrupa gracillima Grube have been identified with the help of tube morphological (light microscopy) and ultrastructural (SEM) studies. This is the first record of the species from the late Pliocene of India. The outer layer of D. gracillima is entirely different from other invertebrates, and the presence of Ridged Prismatic Structure (RRP) exclusively characterises this particular species. The mineralogical analysis (Raman spectroscopy and EDS) reveals a Mg-Ca skeletal for D. gracillima. Isotopic analysis indicates that there is a narrow range of variation in the delta 18 O values of D. gracillima The delta 13 C of D. gracillima shows significant variation and displays the most 13 C depleted values. Based on isotopic analysis it has been inferred that the deposition of sediments took place in a shallow marine environment and D. gracillima thrived in the proximity of hydrocarbon seepages. The present day distributional pattern of D. gracillima indicates that they are mainly confined in the Indo-Pacific region.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"50 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70445147","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}
Utsha Dasgupta, G. Barbieri, S. Vaiani, Anupam Ghosh
Classical (paleo-)ecological indices extracted from benthic foraminiferal assemblages are commonly applied to determine past environmental conditions.We tested the efficiency of selected indices (including wall type proportion, epifaunal/infaunal ratio and pooled diversity indices) on benthic foraminifera from a Holocene shallow marine succession of the Po Delta, in order to evaluate their advantages, limits and differences. The paleoenvironmental record was determined integrating species composition of assemblages. All indices clearly discriminated between low and high riverine influence, even though the boundary at three different core depths revealed their different sensitivity to the faunal response under hanging environmental conditions in terms of organic matter and sediment supply. Specifically, the lowest boundary was highlighted by wall structural types and epifaunal/infaunal ratio that were able to track the first inputs of organic matter provided by the prograding Po River mouths. Upward, low sand concentration and moderate foraminiferal abundance (expressed as Total Foraminiferal Number) indicated significant supplies of fine-grained sediments within a prodelta paleoenvironment. Lastly, diversity indices revealed stressful prodelta conditions with remarkable low diversity and high dominance values. We show that high paleoenvironmental resolution can be obtained through the integration of faunal indices, species composition and sediment grain size within deltaic successions, where many indices should be considered to comprehensively understand the onset of riverine influenced conditions.
{"title":"Potential and limits of benthic foraminiferal ecological indices in paleoenvironmental reconstructions: a case from a Holocene succession of the Po Delta, Italy","authors":"Utsha Dasgupta, G. Barbieri, S. Vaiani, Anupam Ghosh","doi":"10.47894/mpal.66.2.02","DOIUrl":"https://doi.org/10.47894/mpal.66.2.02","url":null,"abstract":"Classical (paleo-)ecological indices extracted from benthic foraminiferal assemblages are commonly applied to determine past environmental conditions.We tested the efficiency of selected indices (including wall type proportion, epifaunal/infaunal ratio and pooled diversity indices) on benthic foraminifera from a Holocene shallow marine succession of the Po Delta, in order to evaluate their advantages, limits and differences. The paleoenvironmental record was determined integrating species composition of assemblages. All indices clearly discriminated between low and high riverine influence, even though the boundary at three different core depths revealed their different sensitivity to the faunal response under hanging environmental conditions in terms of organic matter and sediment supply. Specifically, the lowest boundary was highlighted by wall structural types and epifaunal/infaunal ratio that were able to track the first inputs of organic matter provided by the prograding Po River mouths. Upward, low sand concentration and moderate foraminiferal abundance (expressed as Total Foraminiferal Number) indicated significant supplies of fine-grained sediments within a prodelta paleoenvironment. Lastly, diversity indices revealed stressful prodelta conditions with remarkable low diversity and high dominance values. We show that high paleoenvironmental resolution can be obtained through the integration of faunal indices, species composition and sediment grain size within deltaic successions, where many indices should be considered to comprehensively understand the onset of riverine influenced conditions.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70443961","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}
The total number of recent foraminifera species for Venezuelan marine areas is counted and summarized by major taxonomic groups. Samples from different locations associated with contrasting marine settings were used to review the species richness of the foraminiferal community. Atotal of 930 species were compiled and their synonyms updated. Of this total, 392 species belong to the Rotaliida (42%), 234 to theMiliolida (25%), 155 to the Textulairida (17%), and 79 species to the Lagenida (8%), while the Nodosairida has 18 species (2%), the Spirilinida has 17 (2%), the Polymorphinida has 14 (2%), and the rest belong to the Vaginulinida, Robertinida, Carterinida and Involutinida (12, 6, 2 and 1 species each, respectively). Atotal of 271 species have been identified as endemic to theVenezuelan marine coastal area. This basic diversity analysis of species indicates that the Rotaliida dominate the foraminiferal assemblages along the coast line, followed by the Miliolida and Textulariida, with minor representation of other groups of foraminifera. The distribution of the foraminiferal species, especially benthic, is associated with the different ecoregions and can help serve as indicators for environmental health, marine restoration, and preservation of environmental quality.
{"title":"Richness in recent foraminifera from different locations along Venezuelan coastal ecosystems","authors":"Humberto I. Carvajal Chitty","doi":"10.47894/mpal.66.2.05","DOIUrl":"https://doi.org/10.47894/mpal.66.2.05","url":null,"abstract":"The total number of recent foraminifera species for Venezuelan marine areas is counted and summarized by major taxonomic groups. Samples from different locations associated with contrasting marine settings were used to review the species richness of the foraminiferal community. Atotal of 930 species were compiled and their synonyms updated. Of this total, 392 species belong to the Rotaliida (42%), 234 to theMiliolida (25%), 155 to the Textulairida (17%), and 79 species to the Lagenida (8%), while the Nodosairida has 18 species (2%), the Spirilinida has 17 (2%), the Polymorphinida has 14 (2%), and the rest belong to the Vaginulinida, Robertinida, Carterinida and Involutinida (12, 6, 2 and 1 species each, respectively). Atotal of 271 species have been identified as endemic to theVenezuelan marine coastal area. This basic diversity analysis of species indicates that the Rotaliida dominate the foraminiferal assemblages along the coast line, followed by the Miliolida and Textulariida, with minor representation of other groups of foraminifera. The distribution of the foraminiferal species, especially benthic, is associated with the different ecoregions and can help serve as indicators for environmental health, marine restoration, and preservation of environmental quality.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2020-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70444263","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}
Acid-resistant, chitin-like organic linings of foraminiferal tests in palynological assemblages are commonly considered reliable indicators of marine transgressions despite sparse information on the relationship between the organic and inorganic skeletal components. This knowledge gap constrains reliable application in paleoecological studies. Foraminiferal lining recovery in palynological samples also varieswith the chemicals and temperature used for extraction of organic residues, and care is needed to avoid damage by hydrolysis or over-oxidation. Using samples treated onlywith cold acid, we describe the test-lining relationship for five common benthic foraminiferal species from order Rotaliida in the polluted, eutrophic, microtidal environment of the Black Sea. Papillate and granulate ornament on lining surfaces reflect the morphology of benthic foraminiferal living in the low oxygen environments of the Black Sea where pore size and frequency may be related to survival. Data from 23 surface samples from the Danube delta plain and offshore in the northwest (NW)Black Sea demonstrate the relationship between benthic foraminifera and their linings in a qualitative model characterising environments from delta plain (-1.8 m water depth) to outer shelf and continental slope (>90 m), along a surface salinity gradient from about 5 to 17 psu. Compared with microforaminiferal assemblages in high salinity deltaic and coastal environments of Atlantic and Pacific Oceans, the lining abundances of the semi-marine Danube- region sediments are relatively low but they often exceed the foraminiferal abundances at the same site.A Dissolution Index based on log (organic lining: test ratio) shows that calcite preservation is low in most of the Danube Delta sub-environments. Test and lining deformity, large pore-size, and pyritization of tests and linings appear to reflect hypoxia and eutrophication. The new data provide a baseline for paleocological studies of coastline changes in the Danube Delta region, and for better understanding of marine transgressions in Paratethyan basins.
{"title":"Microforaminiferal linings as proxies for paleosalinity and pollution: Danube Delta example","authors":"P. Mudie, V. Yanko-Hombach","doi":"10.47894/mpal.65.1.02","DOIUrl":"https://doi.org/10.47894/mpal.65.1.02","url":null,"abstract":"Acid-resistant, chitin-like organic linings of foraminiferal tests in palynological assemblages are commonly considered reliable indicators of marine transgressions despite sparse information on the relationship between the organic and inorganic skeletal components. This knowledge gap constrains reliable application in paleoecological studies. Foraminiferal lining recovery in palynological samples also varieswith the chemicals and temperature used for extraction of organic residues, and care is needed to avoid damage by hydrolysis or over-oxidation. Using samples treated onlywith cold acid, we describe the test-lining relationship for five common benthic foraminiferal species from order Rotaliida in the polluted, eutrophic, microtidal environment of the Black Sea. Papillate and granulate ornament on lining surfaces reflect the morphology of benthic foraminiferal living in the low oxygen environments of the Black Sea where pore size and frequency may be related to survival. Data from 23 surface samples from the Danube delta plain and offshore in the northwest (NW)Black Sea demonstrate the relationship between benthic foraminifera and their linings in a qualitative model characterising environments from delta plain (-1.8 m water depth) to outer shelf and continental slope (>90 m), along a surface salinity gradient from about 5 to 17 psu. Compared with microforaminiferal assemblages in high salinity deltaic and coastal environments of Atlantic and Pacific Oceans, the lining abundances of the semi-marine Danube- region sediments are relatively low but they often exceed the foraminiferal abundances at the same site.A Dissolution Index based on log (organic lining: test ratio) shows that calcite preservation is low in most of the Danube Delta sub-environments. Test and lining deformity, large pore-size, and pyritization of tests and linings appear to reflect hypoxia and eutrophication. The new data provide a baseline for paleocological studies of coastline changes in the Danube Delta region, and for better understanding of marine transgressions in Paratethyan basins.","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70441278","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}
Planktonic foraminiferal morphotypes differ in their susceptibilities to post mortem dissolution. Tropical morphotypes are readily assigned to groups that are dissolution-resistant (primarily non-spinose, r) and dissolution-susceptible (primarily spinose walled, s). Morphotypes in the uppermost Quaternary (marine isotope stages MIS 7-2) at Ceara Rise ODP Hole 926A were assigned to these r and s groups, and the stratigraphic distributions of both the morphotypes and the groups examined. Total recovery was co-dominated by s morphotypes (Globigerinoides ruber Morphotype B, Trilobatus sacculifer s.s.) with lesser, but nevertheless abundant, r morphotypes (Menardella menardiisinistral, Truncorotalia excelsadextral). Dissolution intensity, quantified using the dissolution index Res (%) = 100r / (r + s), showed an overall decrease over time, values of Res(%) being negatively correlated with sample depth below the seafloor. It differed more or less markedly between adjacent samples. These fluctuations were greater towards the bottom of the studied section. Between-sample assemblage turnover was quantified using an assemblage turnover index ATIs (SIGMA p i2 - p i1 , in which pi1 and pi2 are the proportional abundances of the ith morphotype in consecutive samples). Values of ATIs for the total assemblage (ATI tot), when assigned to glacial and interglacial MISs, suggested that the mean value of glacial ATItot did not differ significantly from the mean interglacial ATI tot. More variable and greater dissolution in the lower part of the section is reflected in the significant positive correlation between the sample depth and values of ATItot. Assemblage turnover indices were calculated for the dissolution-resistant r and dissolution-susceptible s groups, the latter being calculated in two ways. For ATI sus1, Trilobatus sacculifer was split into several distinguishable morphotypes based on test form. For ATI sus2, these morphotypes were grouped as T. sacculifer s.s. The correlations between sample depth and the ATIres andATIsus2 were not significant. The values of ATIsus2 and ATI res were positively correlated, though mean ATIsus2 was less than mean ATI res. This implies that, despite dissolution, the s group was more stable overall than the r group. Proportional abundances of the s group members T. sacculifer s.s. and G. ruber gr. (including G. ruber Morphotype B) increased through the section, being positively correlated with each other but negatively correlated with depth below the seafloor. In contrast, percentages of the total recovery as M. menardii and T. excelsa were negatively correlated. Menardella menardii was proportionally abundant throughout the interval below mid MIS 5, and T. excelsa was abundant above that depth. Ceara Rise currently lays beneath the North Equatorial Counter Current, which flows seasonally and induces annual phytoplankton blooms. Dextrally coiled T. truncatulinoides, which is also the main coiling direction of our T. excelsa,
{"title":"Quantifying and comparing rates of dissolution and assemblage turnover among planktonic foraminifera; a case study from the Upper Quaternary in ODPHole 926A, Ceara Rise, western tropical Atlantic Ocean","authors":"B. Wilson, L. Hayek, M. A. Pivel","doi":"10.47894/mpal.65.6.01","DOIUrl":"https://doi.org/10.47894/mpal.65.6.01","url":null,"abstract":"Planktonic foraminiferal morphotypes differ in their susceptibilities to post mortem dissolution. Tropical morphotypes are readily assigned to groups that are dissolution-resistant (primarily non-spinose, r) and dissolution-susceptible (primarily spinose walled, s). Morphotypes in the uppermost Quaternary (marine isotope stages MIS 7-2) at Ceara Rise ODP Hole 926A were assigned to these r and s groups, and the stratigraphic distributions of both the morphotypes and the groups examined. Total recovery was co-dominated by s morphotypes (Globigerinoides ruber Morphotype B, Trilobatus sacculifer s.s.) with lesser, but nevertheless abundant, r morphotypes (Menardella menardiisinistral, Truncorotalia excelsadextral). Dissolution intensity, quantified using the dissolution index Res (%) = 100r / (r + s), showed an overall decrease over time, values of Res(%) being negatively correlated with sample depth below the seafloor. It differed more or less markedly between adjacent samples. These fluctuations were greater towards the bottom of the studied section. Between-sample assemblage turnover was quantified using an assemblage turnover index ATIs (SIGMA p i2 - p i1 , in which pi1 and pi2 are the proportional abundances of the ith morphotype in consecutive samples). Values of ATIs for the total assemblage (ATI tot), when assigned to glacial and interglacial MISs, suggested that the mean value of glacial ATItot did not differ significantly from the mean interglacial ATI tot. More variable and greater dissolution in the lower part of the section is reflected in the significant positive correlation between the sample depth and values of ATItot. Assemblage turnover indices were calculated for the dissolution-resistant r and dissolution-susceptible s groups, the latter being calculated in two ways. For ATI sus1, Trilobatus sacculifer was split into several distinguishable morphotypes based on test form. For ATI sus2, these morphotypes were grouped as T. sacculifer s.s. The correlations between sample depth and the ATIres andATIsus2 were not significant. The values of ATIsus2 and ATI res were positively correlated, though mean ATIsus2 was less than mean ATI res. This implies that, despite dissolution, the s group was more stable overall than the r group. Proportional abundances of the s group members T. sacculifer s.s. and G. ruber gr. (including G. ruber Morphotype B) increased through the section, being positively correlated with each other but negatively correlated with depth below the seafloor. In contrast, percentages of the total recovery as M. menardii and T. excelsa were negatively correlated. Menardella menardii was proportionally abundant throughout the interval below mid MIS 5, and T. excelsa was abundant above that depth. Ceara Rise currently lays beneath the North Equatorial Counter Current, which flows seasonally and induces annual phytoplankton blooms. Dextrally coiled T. truncatulinoides, which is also the main coiling direction of our T. excelsa,","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70442945","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}
B. Wilson, P. Farfan, L. Hayek, M. Kaminski, A. Amao, C. Hughes, Sadie Samsoondar, S. Ali, Krystella Rattan, Anastasia A. Baboolal
The Nariva Formation comprises mostly non-calcareous rocks with few calcareous foraminifera, but it is sandwiched geographically in a narrow (<10 km wide) band between the richly calcareous Brasso and Cipero Formations to the north and south respectively. Sixty-one samples were collected from the Nariva Formation at nine transient exposures along a transect trending NNE-SSW across southwestern Central Trinidad. The sparse planktonic foraminiferal assemblages showed the exposures to range in age between Oligocene and early middle Miocene, though many of the samples were of earliest middle Miocene age and coincident with a tectonically-induced transgressive-regressive cycle in the Brasso Formation. The Nariva assemblage at the most southerly exposure, at which the Nariva and Cipero Formations interfingered, was calcareous and of lower bathyal aspect, containing many Planulina wuellerstorfi. The assemblage at this exposure did not differ statistically between the two formations, and was thus said to be of "Cipero aspect", although the presence of rare Elphidium sp. in the Nariva parts of the exposure attests to some downslope transport. Recovery from most other exposures was typically small. Richer, predominantly agglutinated assemblages, however, were obtained from the Tarouba Community Centre, Ben Lomond Quarry, Raphael Street, and Tabaquite Heights. The assemblages were of "Brasso aspect", comprising species illustrated previously from the Brasso Formation. Three exposures were sampled at the Raphael Street site, which covered about ten hectares and had been cleared for development. The rocks at this site are patchily but richly stained with hematite and possible manganese derived from hydrothermal activity. Exposure 1 (13 samples) was subdivided into an almost barren interval (Exposure 1a, 8 samples) and an interval containing abundant Cribrostomoides carapitanus and Trochammina cf. pacifica and lesser Jarvisella karamatensis, Arenogaudryina flexilis and Glaphyrammina americana (Exposure 1b, 5 samples). This assemblage is thought to indicate low dissolved oxygen concentrations at middle to lower bathyal paleodepths. That the Brasso Formation was deposited at neritic to shallower middle bathyal paleodepths, while the Cipero Formation at lower bathyal to abyssal depths, demonstrates that the Nariva Formation was deposited on an eastward-facing paleo-slope. Exposures 2 (9 samples) and 3 (5 samples) are dominated by Simobaculites saundersi Wilson and Kaminski, n. sp., the walls of which do not incorporate calcareous particles. Many samples yielded large quantities of gypsum that, in view of (a) the paleodepth and (b) the rich planktonic foraminiferal recovery from the adjacent Brasso and Cipero Formations, is thought to reflect syndepositional dissolution of foraminiferal calcium carbonate and its precipitation as calcium sulphate. Because both the Nariva Formation and the upper Miocene to lower Pliocene Lower Cruse Member (southern Trinidad) yield
{"title":"Agglutinated and planktonic foraminifera of the Nariva Formation, Central Trinidad, as indicators of its age and paleoenvironment","authors":"B. Wilson, P. Farfan, L. Hayek, M. Kaminski, A. Amao, C. Hughes, Sadie Samsoondar, S. Ali, Krystella Rattan, Anastasia A. Baboolal","doi":"10.47894/mpal.65.1.01","DOIUrl":"https://doi.org/10.47894/mpal.65.1.01","url":null,"abstract":"The Nariva Formation comprises mostly non-calcareous rocks with few calcareous foraminifera, but it is sandwiched geographically in a narrow (<10 km wide) band between the richly calcareous Brasso and Cipero Formations to the north and south respectively. Sixty-one samples were collected from the Nariva Formation at nine transient exposures along a transect trending NNE-SSW across southwestern Central Trinidad. The sparse planktonic foraminiferal assemblages showed the exposures to range in age between Oligocene and early middle Miocene, though many of the samples were of earliest middle Miocene age and coincident with a tectonically-induced transgressive-regressive cycle in the Brasso Formation. The Nariva assemblage at the most southerly exposure, at which the Nariva and Cipero Formations interfingered, was calcareous and of lower bathyal aspect, containing many Planulina wuellerstorfi. The assemblage at this exposure did not differ statistically between the two formations, and was thus said to be of \"Cipero aspect\", although the presence of rare Elphidium sp. in the Nariva parts of the exposure attests to some downslope transport. Recovery from most other exposures was typically small. Richer, predominantly agglutinated assemblages, however, were obtained from the Tarouba Community Centre, Ben Lomond Quarry, Raphael Street, and Tabaquite Heights. The assemblages were of \"Brasso aspect\", comprising species illustrated previously from the Brasso Formation. Three exposures were sampled at the Raphael Street site, which covered about ten hectares and had been cleared for development. The rocks at this site are patchily but richly stained with hematite and possible manganese derived from hydrothermal activity. Exposure 1 (13 samples) was subdivided into an almost barren interval (Exposure 1a, 8 samples) and an interval containing abundant Cribrostomoides carapitanus and Trochammina cf. pacifica and lesser Jarvisella karamatensis, Arenogaudryina flexilis and Glaphyrammina americana (Exposure 1b, 5 samples). This assemblage is thought to indicate low dissolved oxygen concentrations at middle to lower bathyal paleodepths. That the Brasso Formation was deposited at neritic to shallower middle bathyal paleodepths, while the Cipero Formation at lower bathyal to abyssal depths, demonstrates that the Nariva Formation was deposited on an eastward-facing paleo-slope. Exposures 2 (9 samples) and 3 (5 samples) are dominated by Simobaculites saundersi Wilson and Kaminski, n. sp., the walls of which do not incorporate calcareous particles. Many samples yielded large quantities of gypsum that, in view of (a) the paleodepth and (b) the rich planktonic foraminiferal recovery from the adjacent Brasso and Cipero Formations, is thought to reflect syndepositional dissolution of foraminiferal calcium carbonate and its precipitation as calcium sulphate. Because both the Nariva Formation and the upper Miocene to lower Pliocene Lower Cruse Member (southern Trinidad) yield ","PeriodicalId":49816,"journal":{"name":"Micropaleontology","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70440966","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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