117 research outputs found

    Foreword

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    Foreword

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    Selandian-Thanetian larger foraminifera from the lower Jafnayn Formation in the Sayq area (eastern Oman Mountains)

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    The larger foraminifera of the lower part of the Jafnayn Formation outcropping in the Wadi Sayq, in the Paleocene series of the eastern Oman Mountains, have been studied and described in detail. The analysis have allowed us to develop a detailed systematic description of each taxa, constraining their biostratigraphic distribution and defining the associated foraminifera assemblages. The taxonomic study has permitted us to identify each morphotype precisely and describe three new taxa, namely, Ercumentina sayqensis n. gen. n. sp. Lacazinella rogeri n. sp. and Globoreticulinidae new family. The first assemblage is characterized by the presence of Coskinon sp., Dictyoconus cf. turriculus Hottinger and Drobne, Anatoliella ozalpiensis Sirel, Ercumentina sayqensis n. gen. n. sp. Serra-Kiel and Vicedo , Lacazinella rogeri n. sp. Serra-Kiel and Vicedo, Mandanella cf. flabelliformis Rahaghi, Azzarolina daviesi (Henson), Lockhartia retiata Sander, Dictyokathina simplex Smout and Miscellanites globularis (Rahaghi). The second assemblage is constituted by the forms Pseudofallotella persica (Hottinger and Drobne), Dictyoconus cf. turriculus Hottinger and Drobne, Lacazinella rogeri n. sp. Serra-Kiel and Vicedo, Azzarolina daviesi (Henson), Keramosphera? cf. iranica Rahaghi, Lockhartia haimei (Davies), Lockhartia retiata Sander, Sakesaria trichilata Sander, Kathina delseota Smout, Elazigina harabekayisensis Sirel, Daviesina khatiyahi Smout, and Miscellanea juliettae Leppig. The first assemblage can be considered to belong to the Shallow Bentic Zone SBZ2 (early Selandian age), and the second assemblage to the SBZ3 (late Selandian-early Thanetian age).This paper shows, for the first time in the Middle East area, a correlation between the Selandian larger foraminifera and planktonic foraminifera biozones

    Stratigraphy and biostratigraphy (charophytes) of the marine-terrestrial transition in the Upper Eocene of the NE Ebro Basin (Catalonia, Spain)

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    The onset of endorheic sedimentation in the Ebro Basin is a prominent feature of the basin's evolution and has recently been characterized as a rapid event occurring in the Early Priabonian. In the north-eastern part of the basin this event coincides with the deposition of the Artés Formation (Fm.), mainly built up by red beds of alluvial origin. The marine-continental boundary has been poorly studied up to now in the so-called Lluçanès area, and what was previously thought to be the base of the Artés Fm. is actually a transitional unit, which we define as the Sant Boi Formation, which covers the underlying marine Milany Depositional Sequence and passes laterally to the Terminal Complex, extending over 15km along the eastern margin of the Ebro Basin. The Sant Boi Fm. is formed by up to 15-20m of alternating siltstones and lutite, grading upwards to brackish and lacustrine marls and lignite, and represents deposition in a brackish to freshwater floodplain. It is characterized biostratigraphically by the fossil charophyte assemblage Harrisichara lineata, Harrisichara vasiformis-tuberculata and Nodosochara jorbae, from the middle part of the Priabonian. In contrast, the overlying red beds of the Artés Fm. are characterized by assemblages containing Harrisichara tuberculata, Nodosochara jorbae and Lychnothamnus longus from the Late Priabonian. These results are largely consistent with recent magnetostratigraphic studies performed south of the studied area, and have enabled us to refine the stratigraphy of the marine-continental transition in the north-eastern Ebro Basin

    Las biozonas de nummulitidos del Paleoceno Superior-Eoceno Inferior de la Cuenca Pirenaica

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    A nummulitid biozonation for the Upper Paleocene-Lower Eocene Pyrenean Basin is proposed in this work, The main contributions are: a) a new biozone proposed for the early Thanetian, b) a better characterization of the late Thanetian biozone, and c) the recognition of  two different biozones within the Lower Ilerdian.The nummulitid biozones established for the Pyrenean Upper Paleocene-Lower Eocene interval were correlated with the corresponding larger foraminiferal biozones Shallow Benthic Zones (SBZ) and integrated in the standard Paleocene-Eocene Time Scale on the basis of magnetostratigraphic data from the Pyrenean Basin and by correlation with the biozonation of calcareous nannoplankton and planktonic foraminifera in the Eastern and Central part of Tethys.The new biozones defined for tbe Pyrenean Upper Paleocene-Lower Eocene are: Nummulites heberti-Ranikothalia sindensis (early Thanetian), N. catari-Assilina yvettae-A. azilensis (late Thanetian), N. gamardensis-A. dandotica (early Ilerdian l), N. bigurdensis-A. aff. Prisca (early Ilerdian 2), N. carcasonensis-A. arenensis (middle Ilerdian l), N. exilis-A. leymeriei (middle Ilerdian 2), N. involutus-A. pomeroli (late Ilerdian), N. planulatus-N. burdigalensis burdigalensis-A. placentula (early Cuisian), N. praelaevigatus-N, cantabricus-A. laxispira (middle Cuisian), and N. manfredi-N. campesinus-A. mnior (late Cuisian)

    Paleocene Larger Foraminifera from the Pyrenean Basin with a recalibration of the Paleocene Shallow Benthic Zones

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    A taxonomic study of the Paleocene larger foraminifera from the Pyrenean basin has led to the description of sixty taxa including two new species: Alveolina korresensis and Valvulineria bacetai. In this work, we present a chronostratigraphic recalibration of the Paleocene Shallow Benthic Zones SBZ 1 to SBZ 4 based on correlation with calcareous nannofossil and planktic foraminifera biozones, all integrated within the stratigraphic framework of Paleocene platform to basin depositional sequences established for the whole Pyrenean domain. The samples were collected in autochtonous and parautochtonous deposits from ten key stratigraphic sections, representative of coastal to platform margin depositional settings. The results from two sections representing base of slope facies with intercalations of calcareous turbidites, which include penecontemporaneous platform-derived biota have been integrated in the study. The regional chronostratigraphic framework is derived from magneto-biochronological studies carried out in the Zumaia section, the global reference section for the Danian-Selandian and Selandian-Thanetian GSSPs. A new calibration of the Paleocene SBZs is proposed. The SBZ 1 is constrained to the first 1.09m.y. of the Paleocene; this first Paleogene biozone lacks distinct larger foraminiferal markers and thus is defined by an association of non-exclusive taxa composed of Valvulineria patalaensis, Stomatorbina? binkhorsti, Planorbulina? antiqua and Bangiana hanseni. The SBZ 2 now appears as the biozone encompassing most of the Danian stage (from ca. 64.9m.a. to 61.6m.a.), and is characterized by the association of Haymanella elongata, Haymanella paleocenica, Kayseriella decastroi, Rotospirella conica, Pyrenerotalia depressa, Elazigin dienii, Ornatononion moorkensii and Paralockhartia eos. The SBZ 2-SBZ 3 boundary coincides with the base of the Selandian stage (ca. 61.6m.a.). The SBZ 3 biozone is defined by the occurrence of Glomalveolina primaeva, Periloculina slovenica, Vania anatolica, Coskinon rajkae, Fallotella alavensis, Cribrobulimina carniolica, Miscellanea yvettae, Miscellanea juliettae, Miscellanites primitivus, Miscellanites minutus, Ranikothalia soldadensis, “Operculina” heberti and Discocyclina seunesi. The SBZ 3-SBZ 4 boundary is now ascribed to ca. 57.2m.a. The SBZ 4 biozone appears characterized by Glomalveolina levis, Alveolina korresensis, Hottingerina lukasi, Daviesina garumnensis, Assilina yvettae, Assilina azilensis and Nummulites catari. The SBZ 4-SBZ 5 boundary is placed at the Paleocene-Eocene boundary event (ca. 56.0m.a.)

    Paleocene Larger Foraminifera from the Pyrenean Basin with a recalibration of the Paleocene Shallow Benthic Zones

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    A taxonomic study of the larger foraminifera found in Paleocene rocks from the Pyrenean basin has led to the description of sixty taxa including two new species: Alveolina korresensis and Valvulineria bacetai. In this work, we present a chronostratigraphic recalibration of the Paleocene Shallow Benthic Zones (SBZ 1 to SBZ 4) based on correlation with calcareous nannofossil and planktic foraminifera biozones, all integrated within the stratigraphic framework of Paleocene platform to basin depositional sequences established for the whole Pyrenean domain. The samples were collected in autochtonous and parautochtonous deposits from ten key shallow platform stratigraphic sections, representative from coastal to platform margin depositional settings. The results from two base of slope sections with numerous intercalations of calcareous turbidites with penecontemporaneous platform-derived biota have been integrated in the study. The regional chronostratigraphic framework is derived from magneto-biochronological studies carried out in the Zumaia section, global reference section for the Danian-Selandian and Selandian-Thanertian GSSPs. The new calibration of the Paleocene SBZs is summarized as follows. The SBZ 1 is constrained to the first 1.09 m.y. of the Paleocene; this first Paleogene biozone lacks distinct larger foraminifera biomarkers and thus is defined by an association of non-exclusive taxa composed of Valvulineria patalaensis, Stomatorbina? binkhorsti, P.? antiqua and Bangiana hanseni. The SBZ 2 now appears as the biozone encompassing most of the Danian stage (from ca. 64.91 m.y. to 61.6 m.y.), and is characterized by the association of Haymanella elongata, Haymanella paleocenica, Kayseriella decastroi, Rotospirella conica, Pyrenerotalia depressa, Elazigina dienii and Paralockhartia eos. The SBZ 2-SBZ 3 boundary coincides with the base of the Selandian stage (ca. 61.6 m.y.). The SBZ 3 biozone is defined by Glomalveolina primaeva, Periloculina slovenica, Vania anatolica, Coskinon rajkae, Fallotella alavensis, Cribrobulimina carniolica, Miscellanea yvettae, Miscellanea juliettae, Miscellanites primitivus, Miscellanites minutus, Ranikothalia soldadensis, Nummulites heberti and Discocyclina seunesi. The SBZ 3-SBZ 4 boundary is now ascribed to ca. 57.2 m.y. The SBZ 4 biozone appears characterized by Glomalveolina levis, Alveolina korresensis, Hottingerina lukasi, Daviesina garumnensis, Assilina yvettae, Assilina azilensis and Nummulites catari. The SBZ 4-SBZ 5 boundary is placed at the Paleocene-Eocene boundary event (ca. 56.0 m.y.)

    The Bartonian-Priabonian marine record of the eastern South Pyrenean foreland basin (NE Spain): a new calibration of the larger foraminifers and calcareous nannofossil biozonation

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    This study presents a combined biostratigraphic (calcareous nannofossils, larger foraminifers) and magnetostratigraphic study of the Middle and Late Eocene marine units of the Igualada area, eastern Ebro Basin. The studied sections of Santa Maria de Miralles and La Tossa encompass the complete marine succession of the Santa Maria Group, where assemblages rich in larger foraminifers have been studied since the early 1950’s. A total of 224 paleomagnetic sites and 62 biostratigraphic samples were collected along a 1350m-thick section that ranges from chron C20n to chron C16n (∼43Ma to ∼36Ma). The resulting magnetostratigraphy-based chronology challenges existing chronostratigraphic interpretations of these units and results in a new calibration of the biostratigraphic zonations. The base of calcareous nannofossil Zone NP19-20 is pinned down to an older age than its presently accepted attribution, whereas the time span assigned to Zone NP18 is significantly reduced. A revised calibration of larger foraminifers indicates that Zone SBZ18, formerly assigned exclusively to the late Bartonian, extends its range to the earlymost Priabonian, the Bartonian stage being almost entirely represented by Zone SBZ17. A division of Zone SBZ18 into two subzones is proposed

    The early/middle Eocene transition at the Ésera valley (South-Central Pyrenees): Implications in Shallow Benthic Zones (SBZ)

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    An integrated study including magnetostratigraphy, larger benthic foraminifera and calcareous nannofossil biostratigraphy is presented herein. This work was performed in shallow marine siliciclastics rich in larger foraminifera, around the Ypresian/Lutetian boundary in the Ésera valley (South-Central Pyrenees). Although the calcareous nannofossil content in the studied interval is low, not allowing a precise Y/L boundary to be recognised, the taxa found are enough to support the chronostratigraphic attribution. Data obtained in the Ésera valley section has improved the knowledge of larger benthic foraminifera (Nummulites and Assilina) distribution through chron C21. SBZ 11 to SBZ 12 transition took place at the lowermost C21r, as shown in previous works. SBZ 12 assemblages extend into C21n, where the SBZ 12 to SBZ 13 boundary occurs. These data, obtained in shallow marine siliciclastic facies, with in situ fauna, results in a shift of the SBZ 12/SBZ 13 boundary to the Lower Lutetian, younger than previously believed. Accordingly, the Ypresian/Lutetian boundary occurs in SBZ 12. © A. Rodríguez-Pintó, J. Serra-Kiel, G. Bernaola, A. Barnolas, E.L. Pueyo, J. Tosquella, P. Arbués, R. Scholger, 2022 CC BY-SA
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