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Emmanuel Gheerbrant - One of the best experts on this subject based on the ideXlab platform.
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first carbon isotope chemostratigraphy of the ouled abdoun phosphate basin morocco implications for dating and evolution of earliest african placental mammals
Gondwana Research, 2014Co-Authors: Johan Yans, Baadi Bouya, Paola Iacumin, Laszlo Kocsis, Omar Selloum, Jean-yves Storme, Mustapha Mouflih, Mbarek Amaghzaz, Henri Cappetta, Emmanuel GheerbrantAbstract:Abstract The well-known Maastrichtian–Ypresian vertebrate-bearing phosphate series, in the Ouled Abdoun Basin, Morocco, is classically dated using regional selachian biostratigraphic zonation. These marine sediments yielded Paleocene and Eocene mammals comprising the earliest known placentals from Africa. This study provides the first insight into the organic carbon isotope chemostratigraphy (δ 13 C org ) of the Moroccan phosphate series and a refined dating of its vertebrate-bearing levels. Four Paleocene–Eocene sections in the NE Ouled Abdoun quarries show consistent δ 13 C org long term evolutions, from the base to the top: 1) positive trend in phosphorite Bed IIa, beginning with the lower Bone Bed yielding mammals such as Eritherium , Ocepeia , Abdounodus , Lahimia , of early Thanetian and Selandian age; 2) transitional negative trend in the Intercalary phosphorite Beds II/I that includes the Otodus obliquus and Phosphatherium escuilliei Bone Bed of earliest Ypresian age; 3) negative trend to the lowermost δ 13 C org values that are correlative to the early–middle Ypresian interval including ETM 2 and ETM 3 hyperthermal events in the global record; 4) positive trend in chert-enriched facies containing the middle Ypresian EECO global climatic event. Our chemostratigraphic study of the Ouled Abdoun phosphate series provides a new chronostratigraphic framework for calibrating the beginning of the evolution of placental mammals in Africa. The lower Bone Bed level from the Paleocene phosphorite Bed IIa yielding Eritherium is not younger than early Thanetian, and is most likely Selandian. The Phosphatherium Bone Bed in the Intercalary Beds II/I is earliest Ypresian. The phosphorite Bed 0, from which Daouitherium probably came, is early–middle Ypresian, just below the EECO. This suggests that the first large proboscideans evolved after the PETM, during mid-Ypresian warming events. The δ 13 C org study does not support the presence of Lutetian in the NE Ouled Abdoun phosphate series and suggests that a noticeable part of the upper Thanetian is absent.
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first ascertained african condylarth mammals primitive ungulates cf bulbulodentata and cf phenacodonta from the earliest Ypresian of the ouled abdoun basin morocco
Journal of Vertebrate Paleontology, 2001Co-Authors: Emmanuel Gheerbrant, Jean Sudre, Mohamed Iarochene, Abdelkader MoumniAbstract:ABSTRACT We report here the discovery of the first well identified “condylarths” from Africa, from the phosphatic beds of Ouled Abdoun Basin, Morocco, of probable early Ypresian age, which have also yielded the oldest known proboscidean. Abdounodus hamdii n. gen., n. sp. and Ocepeia daouiensis, gen. et sp. nov., show closest relationships with Mioclaenidae and Phenacodonta respectively. Both taxa also have resemblances with South American primitive ungulates, especially Abdounodus which resembles kollpaniine mioclaenids in several derived features, mostly related to a similar crushing specialization. However divergent specializations in Abdounodus and kollpaniines strongly suggest their parallelisms, in accordance with their age disparity. Some features of Abdounodus appear to be even original with respect to known mioclaenids. Though Ocepeia shares peculiar derived features with phenacodontids, it is strikingly specialized in its secondarily simplified p4, indicating sister-taxa relationships within Taxe...
Kaan Sayit - One of the best experts on this subject based on the ideXlab platform.
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evolution of an early eocene pull apart basin in the central pontides northern turkey new insights into the origin of the north anatolian shear zone
Terra Nova, 2017Co-Authors: Giuseppe Ottria, Luca Pandolfi, Rita Catanzariti, Simone Da Prato, Alessandro Ellero, Chiara Frassi, M. C. Göncüoğlu, Michele Marroni, Leonardo Ruffini, Kaan SayitAbstract:Although the North Anatolian Shear Zone is one of the main lithospheric-scale strike-slip deformation zones in the world, playing a prominent role in the complex geodynamic interaction between the Eurasian, Anatolian and Arabian plates, the onset time of its activity remains highly controversial. Here, we tackle this issue by utilizing nannofossil biostratigraphy on deposits from the Tascilar basin, a pull-apart basin that we have identified inside the North Anatolian Shear Zone overprinting the Intra-Pontide suture zone. The syn-tectonic sedimentary succession of the Tascilar basin developed completely during the early Eocene (Ypresian; CNE4–CNE5 Zones). The strike-slip faulting related to the initial onset of the North Anatolian Shear Zone can likely be constrained within the Ypresian, suggesting that the westward escape of the Anatolian plate along the North Anatolian Shear Zone started in the early Eocene. This article is protected by copyright. All rights reserved.
Dario De Franceschi - One of the best experts on this subject based on the ideXlab platform.
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First record of an Icacinaceae Miers fossil flower from Le Quesnoy (Ypresian, France) amber
Scientific Reports, 2017Co-Authors: Cedric Del Rio, Thomas Haevermans, Dario De FranceschiAbstract:Flowers embedded in amber are rare. Only about 70 flowers or inflorescences have been described among which only one lamiid is known. Nevertheless, these fossils are important to our understanding of evolutionary process and past diversity due to the exceptional preservation of fragile structures not normally preserved. In this work, a new flower named Icacinanthium tainiaphorum sp. nov. from Le Quesnoy (Houdancourt, Oise, France) is described. Our phylogenetic analysis with extant species suggests that the affinity of this flower lies with the family Icacinaceae, close to Natsiatum or Hosiea. The fossil shows a combination of features unknown in extant Icacinaceae and we thus propose the description of a new fossil genus. It reveals a previously unknown diversity in the family and demonstrates the complementarity of different types of fossil preservation for a better understanding of past floral diversity.
Adel Arfaoui - One of the best experts on this subject based on the ideXlab platform.
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organic geochemical study of Ypresian sediments at jebel ousselat tunisia
Geochemistry International, 2008Co-Authors: Adel Arfaoui, Mabrouk MontacerAbstract:This new study was carried out in order to accurately characterize the geochemical pattern of Ousselat organic-rich facies from the Ypresian basin in central-northern Tunisia. It has been found that the organic matter is located towards the end of diagenesis/beginning of catagenesis. This assumption is supported by the relative low Tmax values (429–439°C) and by steranes maturity parameters such as C29 αα 20S/(20S + 20R), and C29 ββ/(ββ + αα). High HI values and the abundance of saturates (1–83%) compared to aromatics (2–27%) are unequivocal evidence of type-II organic matter as indicated by a high abundance of cholestane and the predominance of short-chain n-alkanes centred at n-C18 and at n-C20. Total organic carbon (TOC) content and petroleum potential values suggest that the Ypresian period corresponds to an anoxic event which led to the accumulation and preservation of large quantities of organic matter with high primary production. Due to their geochemical characteristics, the Lower Eocene facies represent a new potential source rocks in central-northern Tunisia.
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comparative study between rock eval pyrolysis and biomarkers parameters a case study of Ypresian source rocks in central northern tunisia
Marine and Petroleum Geology, 2007Co-Authors: Adel Arfaoui, Mabrouk Montacer, Fekri Kamoun, Adel RiganeAbstract:Abstract Sedimentary rock samples from the Ypresian Basin, in central-northern Tunisia, were analyzed by two well-proven organic geochemical methods: Rock-Eval (RE) pyrolysis and gas chromatography–mass spectrometry (GC–MS) analysis. These techniques were uses to obtain independent parameters on organic matter composition, its thermal maturity, and environment of deposition. This study reveals a close concordance between Rock-Eval pyrolysis data and polycyclic biomarkers parameters such as hopanes and steranes. RE pyrolysis in conjunction with GC–MS analysis show that the Ypresian Basin sediments contain a variable but notable organic-rich facies during the Ypresian and prove an unequivocal evidence for Type-II organic matter, which lies dominantly prior to the peak stage of the conventional oil window (end of diagenesis-beginning of catagenesis). The case study from the Ypresian Basin shows that these methods remain undoubtedly suitable for a good assessment of the petroleum potential of source rocks and rapid geochemical characterization of sedimentary organic matter.
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usefulness of rock eval pyrolysis liquid chromatography and gc ms in the characterization of Ypresian chaker organic matter central northern tunisia
Fuel Processing Technology, 2007Co-Authors: Adel Arfaoui, Mabrouk Montacer, Dorra MehdiAbstract:Abstract The present paper compares Rock-Eval pyrolysis (RE), liquid chromatography (L.C), and gas chromatography-mass spectrometry (GC–MS) data from a geochemical study of Jebel Chaker organic-rich facies, in central-northern Tunisia, in order to obtain independent parameters on organic matter source, composition, and thermal maturity. This study shows a clear evidence of planktonic organic matter as indicated by the hydrogen index, n-alkanes distribution, predominance of saturated, and the high concentration of cholestane. The thermal maturity of Ypresian organic matter was estimated by T max , abundance of hetero (N.S.O) compounds, and sterane geochemical parameters such as C 29 αα 20S / (20S + 20R) and C 29 ββ (ββ + αα) maturity ratios…, to be of low thermal maturity (end of diagenesis–beginning of catagenesis). These data reveal a close concordance between RE, L.C., and GC/MS data, and show that these methods remain valuable and practical for geochemical characterization of sedimentary organic matter.
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geochemical characterization given by rock eval parameters and n alkanes distribution on Ypresian organic matter at jebel chaker tunisia
Resource Geology, 2007Co-Authors: Adel Arfaoui, Mabrouk MontacerAbstract:Sedimentary rock samples from Jebel Chaker in the eastern part of the Ypresian basin in central-northern Tunisia were analyzed using various geochemical methods in order to decipher their organic signature. Examination of the distribution of total organic carbon (1.04–1.82%) suggests that the petroleum potential of Ypresian facies is not ignored in such area. The Ypresian episode permitted the accumulation of organic matter, which is typically marine plankton as indicated by the unimodal distribution of N-alkane at nC18 and by the predominance of the aliphatic hydrocarbons compared to the aromatics. It is concluded that the Ypresian organic matter is relatively immature, as indicated by the high content of polar compounds (3–67%) in bitumen. This conclusion is supported by the relative low Tmax values (433–438°C), suggesting that the organic matter is located towards the end of diagenesis and beginning of catagenesis. These new results testify to the establishment of suboxic conditions that led to the accumulation and preservation of good quantities of organic matter in central-northern Tunisia during the Ypresian. Due to their geochemical characteristics, the Chaker facies represent new potential source rocks in central-northern Tunisia.
Eustoquio Molina - One of the best experts on this subject based on the ideXlab platform.
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integrated stratigraphy of the Ypresian lutetian transition in northern tunisia correlation and paleoenvironmental reconstruction
Journal of African Earth Sciences, 2015Co-Authors: Narjess Karouiyaakoub, Moncef Saïd Mtimet, Moufida Ben Mbarekjemai, Eustoquio MolinaAbstract:Abstract Micropaleontological, mineralogical and geochemical data of the Ypresian–Lutetian transition at the Sejnen section, Tunisia, allowed us to trace a precise correlation with the Global Stratotype Section and Point for the Ypresian/Lutetian boundary recently defined at Gorrondatxe, Spain. The planktic foraminifera assemblages are diversified and enable the biozones of Acarinina pentacamerata (E6), Acarinina cuneicamerata (E7a), Turborotalia frontosa (E7b), Guembelitrioides nuttalli (E8) and Globigerinatheka kugleri/Morozovella aragonensis (E9) to be identified, revealing a hiatus across the E8/E9 boundary. Comparison with the boundary stratotype indicates that the Ypresian/Lutetian boundary in the Sejnen section is located near the base of the E7b zone, just above the first appearance of the species T. frontosa . In the Sejnen section, there are several events identical to those recorded in the boundary stratotype at the Gorrondatxe section. In the middle of this interval, the species diversity of planktic foraminifera is the first to decline, followed by that of the benthic foraminifera in the two sections. Furthermore, taxa with calcareous test peter out while those with agglutinated test reach their peak. There is a marked fall in carbonates in the two sections; while also variations in clay minerals, smectite and kaolinite are very abundant. In the Sejnen section, smectite is the dominant mineral and silica reached its peak. All these data indicate that in northern Tunisia at the Ypresian–Lutetian transition, the marine environment was deep and bathyal, with low energy, oxygenated and characterized by a warm tropical to subtropical climate. Consequently, the Sejnen section may be a suitable section to be defined as auxiliary section (=hypostratotype).
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sea level dynamics and palaeoecological factors affecting trace fossil distribution in eocene turbiditic deposits gorrondatxe section n spain
Palaeogeography Palaeoclimatology Palaeoecology, 2010Co-Authors: Francisco J Rodrigueztovar, Alfred Uchman, Aitor Payros, Xabier Orueetxebarria, Estibaliz Apellaniz, Eustoquio MolinaAbstract:Abstract Ichnological analysis of the upper Ypresian–lower Lutetian interval at the Gorrondatxe section (W Pyrenees, N Spain), reveals a relationship between sea-level dynamics and the eco-sedimentary factors influencing trace fossil assemblages. The 600 m thick section of deep-sea turbiditic deposits contains 41 ichnospecies belonging to 28 ichnogenera, which are typical of the Nereites ichnofacies, and mostly of the Paleodictyon ichnosubfacies, suggesting deposition in a basin plain to fan-fringe setting. The trace fossil diversity and abundance fluctuate, irrespective of turbidite frequency. These ichnological features are strongly affected by trophic level changes related partly to sea-level dynamics according to the sequence stratigraphic interpretations for the studied section. Temperature, oxygenation and substrate changes are also considered as relevant factors. Increased ichnodiversity, particularly among graphoglyptids, coincides with moderate oligotrophy and stable ecological conditions. Eutrophisation, lowered oxygenation and drop of temperature, typical of low sea level, can reduce ichnodiversity.
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integrated magnetobiochronology of the early middle eocene transition at agost spain implications for defining the Ypresian lutetian boundary stratotype
Lethaia, 2008Co-Authors: Juan C. Larrasoaña, Eustoquio Molina, Silvia Ortiz, Concepción Gonzalvo, Simonetta Monechi, Flavia Tori, Josep TosquellaAbstract:In this paper, we present an integrated study of a 115-m-thick section that spans the Ypresian/Lutetian boundary at Agost (Betic Cordillera, SE Spain). Our study includes magnetostratigraphic results and biostratigraphic and palaeoenvironmental data derived from planktic foraminifera, small and larger benthic foraminifera, and calcareous nannofossils. Our results demonstrate that the Agost section is continuous and spans from Zones P9 to P12 (E7 to E10), Zones CP11 to CP14a (NP13 to NP16), Zones SBZ11 to SBZ15, and Chrons C22n to C19r. The first occurrence (FO) of H. nuttalli (base of P10) and the FO of G. nuttalli (base of E8) are found within Chron C20r, at a much younger age (3–5 Myr) than previously considered in standard calibration schemes. Similarly, the boundary between SBZ12 and SBZ13 is located within Chron C21n, also at a younger age than previously considered. On the contrary, the FO of B. inflatus (base of CP12b) is found within Chron C21r, which conforms to the magnetostratigraphically calibrated age of ca. 48 Ma (middle part of C21r) considered in standard calibration schemes. These results corroborate earlier studies and indicate that all the events that have been proposed to mark the Ypresian/Lutetian boundary appear at different stratigraphic intervals and have different ages. Based on our results from Agost and on data from other sections elsewhere, we suggest that the Ypresian/Lutetian boundary might be approximated by the FO of B. inflatus (base of CP12b). The Agost section might be considered as a potential candidate to locate the Global Stratotype Section and Point (GSSP) of the base of the Lutetian Stage, because it includes all the events that might be selected as marker events for the Ypresian/Lutetian boundary and it fulfils most of the geological, biostratigraphic and infrastructure requirements demanded for definition of a GSSP.
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Integrated stratigraphy and chronostratigraphy across the Ypresian-Lutetian transition in the Fortuna Section (Betic Cordillera Spain)
Newsletters on Stratigraphy, 2006Co-Authors: Eustoquio Molina, Silvia Ortiz, Ellen Thomas, Concepción Gonzalvo, Miguel Ángel Mancheño, Birger Schmitz, Katharina Von SalisAbstract:This integrated study across the Ypresian/Lutetian boundary in the Fortuna Section (Spain) allowed us to recognize a bundle of events in the transitional interval between the Ypresian and Lutetian stages. Planktic foraminifera show an apparently continuous succession spanning the planktic foraminiferal zones P9, P10 and P11. Calcareous nannofossils allowed the recognition of the nannofossil subzones NP14b, NP15a, NP15b and of zone NP16. Small benthic foraminiferal assemblages may indicate a hyperthermal event as evidenced by a bloom of Aragonia aragonensis, which is coeval with a major change in clay mineralogy. This event coincides with the first occurrence of Hantkenina specimens at the base of planktonic foraminiferal zone P10 in the uppermost part of nannofossil subzone NP14b, which could be used to define the Ypresian/Lutetian boundary. (Less)
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integrated biostratigraphy across the Ypresian lutetian boundary at agost spain
Revue de Micropaléontologie, 2000Co-Authors: Eustoquio Molina, Concepción Gonzalvo, Vlasta Cosovic, Katharina Von SalisAbstract:Abstract The integrated biostratigraphy of a 112 m thick exposed section near Agost (Southern Spain) was studied to assess its suitability as a Global Stratotype Section and Point (GSSP) for the Early/Middle Eocene (Ypresian/Lutetian) Boundary. This section consists of marls interbedded with calcarenites and detrital turbidite layers deposited in a hemipelagic environment. Planktic foraminifera provided good biozonation from P8 through P11 Zones. The calcareous nannofossil Zones NP13 through NP16, respectively CP11 through CP14a, could be distinguished. The larger foraminiferal Zones SBZ12 to SBZ14 could tentatively be distinguished. The base of the H. nuttalli (P. 10) Zone, which is often used to set the boundary between the Lower and the Middle Eocene (Ypresian/Lutetian) falls at a facies change. The Agost Section can be used as a GSSP only if no better section is found.
