A lower to middle Eocene astrochronology for the Mentelle Basin (Australia) and its implications for the geologic time scale

Autor: Carl Richter, Kenneth G. MacLeod, Sietske J. Batenburg, David De Vleeschouwer, Brian T. Huber, Heiko Pälike, Kirsty M. Edgar, Maximilian Vahlenkamp, Mathieu Martinez, Richard Hobbs, Kara Bogus, Emma Hanson, Yongxiang Li
Přispěvatelé: Center for Marine Environmental Sciences [Bremen] (MARUM), Universität Bremen, Géosciences Rennes (GR), Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Centre National de la Recherche Scientifique (CNRS), University of Birmingham [Birmingham], University of Missouri [Columbia] (Mizzou), University of Missouri System, Nanjing University (NJU), University of Louisiana, University of Exeter, Texas A&M University [College Station], Durham University, Smithsonian Institution, 617462, European Research Council, NE/R012350/1, Natural Environment Research Council, Centre National de la Recherche Scientifique, OCE – 1326927, National Science Foundation, Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
Jazyk: angličtina
Rok vydání: 2020
Předmět:
Zdroj: Earth and Planetary Science Letters
Earth and Planetary Science Letters, Elsevier, 2020, 529, pp.115865. ⟨10.1016/j.epsl.2019.115865⟩
Earth and Planetary Science Letters, 2020, 529, pp.115865. ⟨10.1016/j.epsl.2019.115865⟩
Earth and planetary science letters, 2020, Vol.529, pp.115865 [Peer Reviewed Journal]
ISSN: 0012-821X
DOI: 10.1016/j.epsl.2019.115865⟩
Popis: International audience; The geologic time scale for the Cenozoic Era has been notably improved over the last decades by virtue of integrated stratigraphy, combining high-resolution astrochronologies, biostratigraphy and magnetostratigraphy with high-precision radioisotopic dates. However, the middle Eocene remains a weak link. The so-called “Eocene time scale gap” reflects the scarcity of suitable study sections with clear astronomically-forced variations in carbonate content, primarily because large parts of the oceans were starved of carbonate during the Eocene greenhouse. International Ocean Discovery Program (IODP) Expedition 369 cored a carbonate-rich sedimentary sequence of Eocene age in the Mentelle Basin (Site U1514, offshore southwest Australia). The sequence consists of nannofossil chalk and exhibits rhythmic clay content variability. Here, we show that IODP Site U1514 allows for the extraction of an astronomical signal and the construction of an Eocene astrochronology, using 3-cm resolution X-Ray fluorescence (XRF) core scans. The XRF-derived ratio between calcium and iron content (Ca/Fe) tracks the lithologic variability and serves as the basis for our U1514 astrochronology. We present a 16 million-year-long (40-56 Ma) nearly continuous history of Eocene sedimentation with variations paced by eccentricity and obliquity. We supplement the high-resolution XRF data with low-resolution bulk carbon and oxygen isotopes, recording the long-term cooling trend from the Paleocene-Eocene Thermal Maximum (PETM – ca. 56 Ma) into the middle Eocene (ca. 40 Ma). Our early Eocene astrochronology corroborates existing chronologies based on deep-sea sites and Italian land sections. For the middle Eocene, the sedimentological record at U1514 provides a single-site geochemical backbone and thus offers a further step towards a fully integrated Cenozoic geologic time scale at orbital resolution.
Databáze: OpenAIRE
Externí odkaz: