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1. Hydro-geophysical and geochemical studies of the aquifer systems in El Kef region (Northwestern Tunisia).

Author

Ayadi, Yosra, Redhaounia, Belgacem, Mokadem, Naziha, Zighmi, Karim, Dhaoui, Mohamed, and Hamed, Younes

Subjects
*GROUNDWATER recharge, *GEOCHEMICAL modeling, *GEOLOGICAL basins, *AQUIFERS, *HYDROLOGIC cycle, *ANALYTICAL geochemistry, *GROUNDWATER
Abstract

In El Kef region, Northwestern Tunisia, the evolution of the agricultural and industrial sectors has exacerbated the need for water which caused a significant increase in groundwater extraction. In this context, several geologic and geophysical studies conducted on the groundwater resources of the concerning area were meant to give us insight into the geometry of the reservoirs and structural architecture of the basin and to identify the various reservoirs such as the Mio-Plio-Quaternary, the Lower Eocene and the Campanian–Maastrichtian aquifers. In this study, we used the geochemical study and analysis of gravity data (Horizontal and vertical derivative, horizontal gravity gradient maxima...) to improve the knowledge of the dip and direction fault and the geological structures in El Kef region (NW Tunisia) that control the groundwater hydrodynamic. Furthermore, the techniques of horizontal gradient and upward extension were applied to determine the gravity lineaments that represent the location of density contrasts and to locate the various faults that contribute to the structuring of the study area. Additionally, this study aims to assess the spatio-temporal evolution of the hydrodynamic parameters of the aquifers and to characterize the groundwater mineralization (salinity, chemical facies relationship, etc.). Our study showed the presence of four types of water facies: Ca–Mg–SO4; Na–Cl–NO3; Ca–Mg–HCO3 and Na–K–HCO3. The isotopic study is used to provide some information about the groundwater recharge and to define the different sources of water mixing. That way we could have better understanding to the hydrologic cycle and to the paleoclimate of the study area. Generally, the geochemically evolved groundwaters of the aquifer systems of El Kef region are relatively isotopically depleted when compared to the present day meteoric waters reflecting recharge under cold climate and high altitude. Conversely, the continuous increase of the annual mean temperature and the decrease of precipitations have been observed for the second half of the 20th century in North Africa. It is likely related to the warmer and drier conditions associated with the climate change phenomenon. [ABSTRACT FROM AUTHOR]

Published
2019
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3. Détection de la circulation de virus West Nile chez les Équidés dans le nord-ouest de la Tunisie.

Author

Ben Hassine, T., Hammami, S., Elghoul, H., and Ghram, A.

Abstract

Copyright of Bulletin de la Société de Pathologie Exotique is the property of John Libbey Eurotext Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2011
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4. Factors affecting consistency and accuracy in identifying modern macroperforate planktonic foraminifera

Author

Fenton, Isabel S., Baranowski, Ulrike, Boscolo-Galazzo, Flavia, Cheales, Hannah, Fox, Lyndsey, King, David J., Larkin, Christina, Latas, Marcin, Liebrand, Diederik, Miller, C. Giles, Nilsson-Kerr, Katrina, Piga, Emanuela, Pugh, Hazel, Remmelzwaal, Serginio, Roseby, Zoe A., Smith, Yvonne M., Stukins, Stephen, Taylor, Ben, Woodhouse, Adam, Worne, Savannah, Pearson, Paul N., Poole, Christopher R., Wade, Bridget S., and Purvis, Andy

Subjects
Science & Technology, EXTINCTION, AGREEMENT, 04 Earth Sciences, Paleontology, EL KEF, RECONSTRUCTION, 06 Biological Sciences, Life Sciences & Biomedicine, CRETACEOUS-TERTIARY BOUNDARY
Abstract

Planktonic foraminifera are widely used in biostratigraphic, palaeoceanographic and evolutionary studies, but the strength of many study conclusions could be weakened if taxonomic identifications are not reproducible by different workers. In this study, to assess the relative importance of a range of possible reasons for among-worker disagreement in identification, 100 specimens of 26 species of macroperforate planktonic foraminifera were selected from a core-top site in the subtropical Pacific Ocean. Twenty-three scientists at different career stages - including some with only a few days experience of planktonic foraminifera - were asked to identify each specimen to species level, and to indicate their confidence in each identification. The participants were provided with a species list and had access to additional reference materials. We use generalised linear mixed-effects models to test the relevance of three sets of factors in identification accuracy: participant-level characteristics (including experience), species-level characteristics (including a participant's knowledge of the species) and specimen-level characteristics (size, confidence in identification). The 19 less experienced scientists achieve a median accuracy of 57%, which rises to 75% for specimens they are confident in. For the 4 most experienced participants, overall accuracy is 79%, rising to 93% when they are confident. To obtain maximum comparability and ease of analysis, everyone used a standard microscope with only 35 × magnification, and each specimen was studied in isolation. Consequently, these data provide a lower limit for an estimate of consistency. Importantly, participants could largely predict whether their identifications were correct or incorrect: their own assessments of specimen-level confidence and of their previous knowledge of species concepts were the strongest predictors of accuracy.

Published
2018

5. The Chicxulub asteroid impact and mass extinction at the Cretaceous-Paleogene boundary

Author

Philippe Claeys, Christian Koeberl, Wolf Uwe Reimold, Vivi Vajda, Charles S. Cockell, Sean P. S. Gulick, Tobias Salge, Clive R. Neal, David A. Kring, Kenneth G. MacLeod, Douglas J. Nichols, Jay Melosh, Paul R. Bown, Joanna Morgan, J.M. Grajales-Nishimura, Michael T. Whalen, Penny Barton, Kirk R. Johnson, Greg Ravizza, Arthur R. Sweet, Elisabetta Pierazzo, Kazuhisa Goto, Robert P. Speijer, Gareth S. Collins, Takafumi Matsui, Gail L. Christeson, Eric Robin, Tamara J. Goldin, Peter Schulte, Wolfgang Kiessling, José A. Arz, Alessandro Montanari, Laia Alegret, Jaime Urrutia-Fucugauchi, Richard D Norris, Alexander Deutsch, Mario Rebolledo-Vieyra, Pi Suhr Willumsen, Richard A. F. Grieve, Timothy J. Bralower, Ignacio Arenillas, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), University of Zaragoza - Universidad de Zaragoza [Zaragoza], University of Cambridge [UK] (CAM), Department of Earth Sciences [UCL london], University College of London [London] (UCL), Pennsylvania State University (Penn State), Penn State System, Jackson School of Geosciences (JSG), University of Texas at Austin [Austin], Earth System Science Group [Brussels] (ESSc), Vrije Universiteit Brussel (VUB), Planetary and Space Sciences Research Institute [Milton Keynes] (PSSRI), Centre for Earth, Planetary, Space and Astronomical Research [Milton Keynes] (CEPSAR), The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU), The Open University [Milton Keynes] (OU), Imperial College London, Institut für Planetologie [Münster], Westfälische Wilhelms-Universität Münster = University of Münster (WWU), University of Vienna [Vienna], School of Engineering [Tohoku Univ], Tohoku University [Sendai], Instituto Mexicano del Petróleo (IMP), Earth Sciences Sector, Natural Resources Canada (NRCan), Denver Museum of Nature and Science, Museum für Naturkunde [Berlin], Department of Lithospheric Research [Wien], Universität Wien, Center for Lunar Science and Exploration [Houston], Lunar and Planetary Institute [Houston] (LPI), Department of Geological Sciences [Columbia], University of Missouri [Columbia] (Mizzou), University of Missouri System-University of Missouri System, Dept of Complex Science and Engineering, Graduate School of Frontier Science, The University of Tokyo (UTokyo), Purdue University [West Lafayette], Osservatorio Geologico di Coldigioco (OGC), Department of Civil and Environmental Engineering and Earth Science [Notre Dame] (CEEES), University of Notre Dame [Indiana] (UND), Scripps Institution of Oceanography (SIO - UC San Diego), University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), Planetary Science Institute [Tucson] (PSI), Department of Geology and Geophysics [Mānoa], University of Hawai‘i [Mānoa] (UHM), Centro de Investigacion Cientifica de Yucatan (CICY), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Bruker Nano GmbH, Department of Earth and Environmental Sciences [Leuven] (EES), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Universidad Nacional Autónoma de México = National Autonomous University of Mexico (UNAM), Department of Earth and Ecosystem Sciences [Lund], Lund University [Lund], University of Alaska [Fairbanks] (UAF), Earth System Sciences, Isotope Geology and Evolution of Paleo-Environmnents, Chemistry, Geology, Westfälische Wilhelms-Universität Münster (WWU), Earth and Atmospheric Sciences [Purdue University], Scripps Institution of Oceanography (SIO), University of California-University of California, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Universidad Nacional Autónoma de México (UNAM)

Subjects
Geologic Sediments, 010504 meteorology & atmospheric sciences, event, Cretaceous–Paleogene boundary, 010502 geochemistry & geophysics, Extinction, Biological, 01 natural sciences, Minor Planets, KT boundary, Paleontology, perturbations, Phanerozoic, western north-atlantic, Animals, 14. Life underwater, Deccan Traps, Mesozoic, dinosaurs, Mexico, 0105 earth and related environmental sciences, new-zealand, Extinction event, Multidisciplinary, Extinction, crater, Fossils, k-p boundary, 15. Life on land, el kef, tertiary boundary, Impact, 13. Climate action, Asteroid or comet, Flood basalt, mass extinction, [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology, Paleogene, yucatan peninsula, survivorship, Geology
Abstract

The Fall of the Dinosaurs According to the fossil record, the rule of dinosaurs came to an abrupt end ∼65 million years ago, when all nonavian dinosaurs and flying reptiles disappeared. Several possible mechanisms have been suggested for this mass extinction, including a large asteroid impact and major flood volcanism. Schulte et al. (p. 1214 ) review how the occurrence and global distribution of a global iridium-rich deposit and impact ejecta support the hypothesis that a single asteroid impact at Chicxulub, Mexico, triggered the extinction event. Such an impact would have instantly caused devastating shock waves, a large heat pulse, and tsunamis around the globe. Moreover, the release of high quantities of dust, debris, and gases would have resulted in a prolonged cooling of Earth's surface, low light levels, and ocean acidification that would have decimated primary producers including phytoplankton and algae, as well as those species reliant upon them.

Published
2010

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