Paul, Hilary A.; Zachos, James C.; Flower, Benjamin P. (1996): A high-resolution geochemical record of orbitally forced variations in ice-volume and ocean chemistry across the Oligocene/Miocene boundary. Geological Society of America (GSA), Boulder, CO, United States, In: Anonymous, Geological Society of America, 28th annual meeting, 28 (7), 121, georefid:1997-048309
Abstract:
A high resolution (every 4-5 kyr) benthic foraminiferal oxygen and carbon isotope record was constructed for an approximately 3 million year long section of pelagic sediment spanning the Oligocene/Miocene boundary (22.7-25.6 Ma) at Site 929 (4358 m water depth), on Ceara Rise in the western equatorial Atlantic. Key findings include (1) detailed characterization of a large-scale transient glaciation at the O/M boundary (Mi-1 event of Miller et al., 1992), (2) concentrations of variance in climate and ocean chemistry at periods of 19-23 kyr and 41 kyr throughout the interval, and (3) a gradual increase in the amplitude of low frequency (440 kyr) oscillations in carbon isotopic composition that peaks at Mi-1.To evaluate the nature of the low frequency cycles in oxygen and carbon isotopic ratios we constructed lower resolution (every 20 kyr) records from benthic and planktonic foraminifera as well as bulk carbonate at a shallower site on Ceara Rise, Site 926 (3598 m water depth). The Site 926 benthic and planktonic records show a similar range of variability in oxygen isotope values suggesting that the higher frequency oscillations recorded prior to and during the Mi-1 glacial event at Site 929 might also reflect variations in ice-volume. Moreover, parallel trends in the carbon isotopic records of bulk sediment, benthic, and planktonic foraminifera suggest that the low frequency cycles and long-term drift towards heavier carbon isotope values represent changes in the global carbon isotope budget.
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West: -46.0000 East: -39.0000 North: 7.0000 South: 3.0000
West: NaN East: NaN North: NaN South: NaN
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