Paleoceanographic changes across OAE 2 inferred from resilient foraminifera and XRF data at southern high latitudes (IODP Sites U1513 and U1516, Mentelle Basin, SW Australia)

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中文题名根据南部高纬度地区弹性有孔虫和XRF数据推断的OAE 2期间的古海洋学变化(澳大利亚西南部曼泰勒盆地IODP站点U1513和U1516)
作者Giulia Amaglio1CA1;Maria Rose Petrizzo12;Erik Wolfgring1,23;Ann Holbourn34;Wolfgang Kuhnt35
作者单位1Dipartimento di Scienze della Terra “Ardito Desio”, Università degli Studi di Milano, via Mangiagalli 34, I-20133 Milano, Italy;2University of Vienna, Department of Palaeontology, Josef Holaubek Platz 2, 1090 Vienna, Austria;3Institut für Geowissenschaften, Christian-Albrechts-Universität, Olshausenstr 40, 24118 Kiel, Germany
刊名Palaeogeography, Palaeoclimatology, Palaeoecology
2025
657
摘要
The Oceanic Anoxic Event 2 (OAE 2), across the Cenomanian-Turonian boundary interval, was characterized by global environmental perturbations in the carbon cycle that affected the abundance and biodiversity of marine biota and their paleoecological preferences. International Ocean Discovery Program (IODP) Sites U1513 and U1516 in the Mentelle Basin (offshore SW Australia) reveal a continuous foraminiferal record that document the adaptative response of biota, suitable to reconstruct paleoenvironmental conditions in the water column and at the seafloor. Below and during the initial part of the OAE 2, we do not observe changes in the benthic foraminiferal assemblages dominated by Gavelinella, Gyroidinoides and Stensioeina. Agglutinated foraminifera are rare, whereas Microhedbergella and Muricohedbergella dominate the planktonic foraminiferal assemblage, indicating possible eutrophication episodes below and during the OAE 2 associated to an increase in terrigenous sediments. However, a positive peak in Zr/Rb ratios, the unique occurrence of Stensioeina truncata, and the increase in epifaunal- infaunal ratio, particularly at Site U1516, indicate a greater eolian transportation of sediments and an enhanced oxygenation at the seafloor, which might be related to the identification of the Plenus Cold Event (PCE) at high latitudes. An interval of low CaCO3 content within the peak of OAE 2 is characterized by the absence of foraminifera and dominance of siliceous organisms. It is also marked by a sudden enhancement of the hydrological cycle, probably causing a shoaling of the Calcite Compensation Depth (CCD). However, Site U1516 shows few samples with a change in the planktonic and benthic foraminiferal assemblage. Above this interval, both sites are characterized by a different benthic foraminiferal assemblage with the occurrence of Conorboides claytonensis in the uppermost part of OAE 2. At Site U1513, epi-infaunal ratio increase, planktonic foraminifera show the highest diversification, rainfall decreases, indicating a recovery towards a well-stratified water column with mesotrophic regimes and a drier environment, whereas Site U1516 shows a slower recovery.

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