Skip to main content

ORIGINAL RESEARCH article

Front. Earth Sci.
Sec. Sedimentology, Stratigraphy and Diagenesis
Volume 12 - 2024 | doi: 10.3389/feart.2024.1405768
This article is part of the Research Topic Advances in Ocean Deoxygenation Events and their impacts in Earth’s history View all articles

Calcareous nannoplankton fluctuation within the Albian-Cenomanian Boundary Event of the Tethyan Himalaya

Provisionally accepted
Mihaela Melinte-Dobrinescu Mihaela Melinte-Dobrinescu 1*Xi Chen Xi Chen 2Eliza Anton Eliza Anton 1Vlad Apotrosoaei Vlad Apotrosoaei 1Hanwei Yao Hanwei Yao 2
  • 1 National Research and Development Institute for Marine Geology and Geoecology, Bucharest, Romania
  • 2 State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences and Resources, China University of Geosciences, Wuhan, Hubei Province, China

The final, formatted version of the article will be published soon.

    A 29 m-thick hemipelagic succession, situated in S Tibet, within the Tethyan Himalaya tectonic unit, has been investigated for its calcareous nannofossil content. A total of 17 samples were subject to qualitative and semi-quantitative analysis. The studied interval belongs to the upper Albian-lowermost Cenomanian and extends in the UC0 nannofossil zone; based on the last occurrence of Hayesites albiensis, the UC0a and UC0b-c subzones were recognized. The most abundant nannofossil of the Youxia section is Watznaueria barnesiae. Other common taxa are Eiffellithus turriseiffelii, Eprolithus floralis, Rhagodiscus spp., and Zeugrhabdotus spp. In the lowermost part of the studied section, below the beginning of the Albian-Cenomanian Boundary Event (ACBE), i.e., prior the 13C positive excursion related to OAE1d, the nannofossils confined to high paleolatitudes Repagulum parvidentatum, Seribiscutum primitivum, and Sollasites horticus are present with a low abundance. This occurrence is believed to mirror a short episode of cooler surface waters linked to a transgressive event. The nannofossil abundance and diversity, along with the fluctuation patterns of the nutrient and temperature indices throughout the section, reflects a primary signal of mesotrophic to eutrophic conditions from the base of the succession up to the two oldest 13C peaks of ACBE, late Albian in age, including within the OAE1d. By contrast, the dominance of Watznaueria barnesiae, representing than 80% of the total assemblages, along with the significant drop in abundance and diversity shown by nannofossils within late phases of ACBE, are interpreted as a diagenetic signal. Mesotrophic to eutrophic conditions returned towards the top of the studied succession, where Biscutum constans and Zeugrhabdotus erectus show again a higher abundance.

    Keywords: Late Albian-early Cenomanian, Oceanic anoxic event 1d, nannofossils, Paleoproductivity, S Tibet late Albian-early Cenomanian, S Tibet Font: Italic Formatted: Font: Italic

    Received: 23 Mar 2024; Accepted: 29 Aug 2024.

    Copyright: © 2024 Melinte-Dobrinescu, Chen, Anton, Apotrosoaei and Yao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Mihaela Melinte-Dobrinescu, National Research and Development Institute for Marine Geology and Geoecology, Bucharest, Romania

    Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.