New Sr and Nd isotope data from phosphorites of the Maknassy-Mezzouna basin (Tunisia) and their geochronological and paleo-oceanographical implications

Article Article scientifique Article New Sr and Nd isotope data from phosphorites of the Maknassy-Mezzouna basin (Tunisia) and their geochronological and paleo-oceanographical implications eng 2023-05-14 2023-05-14 author Sassi Sinda 0000-0002-5532-8754 922914 author Ounis Anouar 528961 author Horchani-Naifer Karima author Schaltegger Urs 0000-0003-4404-8607 134356 Services communs du département des sciences de la terre (DETCO) author Chiaradia Massimo 0000-0003-4943-2480 110575 Services communs du département des sciences de la terre (DETCO) 1599-1612 10.1007/s00531-023-02316-3 1437-3254 https://link.springer.com/10.1007/s00531-023-02316-3 Paleocene–Eocene phosphorite beds from three major outcrops of the Maknassy-Mezzouna basin (Central-Tunisia) were geochemically investigated to improve local stratigraphy, determine their ages, and attempt to constrain ocean circulation. 87Sr/86Sr ratios of phosphate materials from the Chouabine Formation display a large variation even within the same deposit (87Sr/86Sr between 0.707782 and 0.707830). Based on the Sr isotope data obtained in teeth enamels, further supported by the results in coprolites, Sr isotope ages of 57 ± 1.1 Ma were attributed to Layers I and II, and 62 ± 1.4 Ma to Layer III. These results assign a Paleocene Epoch for the principal phosphate series. The 87Sr/86Sr value of teeth enamel sample from the upper phosphate bed suggests an age of 46 ± 1 Ma for this sequence. Furthermore, the Nd isotopic compositions of these samples were used as a tracer for seawater circulation. The 143Nd/144Nd values of the analyzed samples vary between 0.512174 and 0.512202, corresponding to εNdCHUR between – 8.1 and – 8.4. These values are similar to those reported from Gafsa-Metlaoui basin, southern Tunisia and other North African phosphorite deposits. These data are reminiscent of those of the Atlantic Ocean, which is new argument of the overturning of Tethys Circumglobal Current during the Paleogene period. The obtained results suggest water exchange between Tethys and Atlantic Ocean during this period. Phosphate Sr isotope Nd isotope Tethys seawater Tunisia Dewey 550 42 Département des sciences de la Terre 154 false 692 Mineral Resources and Geofluids 663 Isotope Geochemistry, Geochronology and Thermochronology International journal of earth sciences 112 5 ea47c7a1-7c59-4ee1-9b5e-3d1f8883c11e Article (Published version) Restricted Article-scientifique-from-crossref.pdf 5403577 application/pdf 5c4b2c7af3f2c99e47b4117a386c175f0fd4c4855d4bb6121e36a49294007b1f restrictedAccess Faculté des sciences / Section des sciences de la Terre et de l'Environnement / Département des sciences de la Terre

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New Sr and Nd isotope data from phosphorites of the Maknassy-Mezzouna basin (Tunisia) and their geochronological and paleo-oceanographical implications	International journal of earth sciences			2023	146	0

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