Exploring the paleoceanographic changes registered by planktonic foraminifera across the Cenomanian-Turonian boundary interval and Oceanic Anoxic Event 2 at southern high latitudes in the Mentelle Basin (SE Indian Ocean)

• Published in: Global and Planetary Change
• Main Authors: Petrizzo, Maria Rose, Watkins, David K., MacLeod, Kenneth G., Hasegawa, Takashi, Huber, Brian T., Batenburg, Sietske J., Kato, Tomonori
• Other Authors: M.R. Petrizzo, D.K. Watkin, K.G. Macleod, T. Hasegawa, B.T. Huber, S.J. Batenburg, T. Kato
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2021
• Subjects: Planktonic foraminifera; Stable carbon and oxygen isotope; Oceanic Anoxic Event 2; Cenomanian/Turonian boundary; Paleoceanography; Southern high latitudes; Settore GEO/01 - Paleontologia e Paleoecologia; Indian
• Online Access: http://hdl.handle.net/2434/869684; https://doi.org/10.1016/j.gloplacha.2021.103595

Planktonic foraminiferal population dynamics and benthic foraminiferal and radiolaria distributions combined with δ13C and δ18O measurements of both bulk carbonate and foraminifera provide clues concerning the paleoceanographic changes across the Cenomanian-Turonian boundary interval and the Oceanic Anoxic Event 2 (OAE 2) at southern high latitudes. Samples analyzed are from Integrated Ocean Discovery Program (IODP) Expedition 369 Site U1516 in the Mentelle Basin (eastern flank of the Naturaliste Plateau, Indian Ocean, SW Australia). Site U1516 was located at 60◦–62◦S paleolatitude during the mid-Cretaceous, and it is the first high latitude locality in the Southern Hemisphere where planktonic foraminifera are consistently recorded across the OAE 2 interval and its associated positive δ13C excursion. The sedimentary record at Site U1516 consists of a sequence of alternating black, dark greenish gray, and light greenish gray claystone in the Cenomanian that grade to white and light gray calcareous chalk interbedded with chert in the Turonian. The correlation between the δ13C and δ18O profiles at Site U1516 and the European reference section at Eastbourne (England) coupled with the integrated calcareous plankton biostratigraphy and stable isotopic data at Site U1516, indicate that a complete record of OAE 2 at Site U1516 was recovered. Below and in the lower part of OAE 2, the planktonic foraminiferal assemblages are dominated by small-sized (125–38 μm) opportunistic species of Microhedbergella and radiolaria indicating a dominantly eutrophic regime. Above the onset of OAE 2, a trough in the δ13C profile (Plenus Carbon Isotope Event: P-CIE) coinciding with a δ18O increase may correspond to the Plenus Cold Event as observed at low latitudes, although no evidence of cooling is registered in the microfossil assemblages. At Site U1516, the middle part of OAE 2 at the initiation of the plateau phase of the δ13C profile is masked by absence of carbonate, by the highest TOC values, and high biogenic silica (dominance of ...