Bohaty, Steven M; Zachos, James C (2003): Carbon and oxygen isotopic compositions of Cibicidoides spp. and fine fraction separates (<10 µm) from ODP Holes 113-689B, 119-738B, and 120-748B. PANGAEA, https://doi.org/10.1594/PANGAEA.713540, Supplement to: Bohaty, SM; Zachos, JC (2003): Significant Southern Ocean warming event in the late middle Eocene. Geology, 31(11), 1017-1020, https://doi.org/10.1130/G19800.1
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A prominent middle Eocene warming event is identified in Southern Ocean deep-sea cores, indicating that long-term cooling through the middle and late Eocene was not monotonic. At sites on Maud Rise and the Kerguelen Plateau, a distinct negative shift in d18O values (~1.0 per mil) is observed ca. 41.5 Ma. This excursion is interpreted as primarily a temperature signal, with a transient warming of 4°C over 600 k.y. affecting both surface and middle-bathyal deep waters in the Indian-Atlantic region of the Southern Ocean. This isotopic event is designated as the middle Eocene climatic optimum, and is interpreted to represent a significant climatic reversal in the midst of middle to late Eocene deep-sea cooling. The lack of a significant negative carbon isotope excursion, as observed during the Paleocene-Eocene thermal maximum, and the gradual rate of high-latitude warming suggest that this event was not triggered by methane hydrate dissociation. Rather, a transient rise in pCO2 levels is suspected, possibly as a result of metamorphic decarbonation in the Himalayan orogen or increased ridge/arc volcanism during the late middle Eocene.
Median Latitude: -61.725000 * Median Longitude: 49.396760 * South-bound Latitude: -64.517000 * West-bound Longitude: 3.099900 * North-bound Latitude: -58.441000 * East-bound Longitude: 82.787800
Date/Time Start: 1987-01-16T08:00:00 * Date/Time End: 1988-03-15T11:00:00
113-689B * Latitude: -64.517000 * Longitude: 3.099900 * Date/Time Start: 1987-01-16T08:00:00 * Date/Time End: 1987-01-18T06:45:00 * Elevation: -2091.0 m * Penetration: 297.3 m * Recovery: 229.45 m * Location: South Atlantic Ocean * Campaign: Leg113 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 33 cores; 297.3 m cored; 0 m drilled; 77.2 % recovery
119-738B * Latitude: -62.709000 * Longitude: 82.787800 * Date/Time Start: 1988-01-10T16:30:00 * Date/Time End: 1988-01-11T18:45:00 * Elevation: -2263.0 m * Penetration: 214.3 m * Recovery: 170.85 m * Location: Indian Ocean * Campaign: Leg119 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 24 cores; 214.3 m cored; 0 m drilled; 79.7 % recovery
120-748B * Latitude: -58.441000 * Longitude: 78.998100 * Date/Time Start: 1988-03-14T07:30:00 * Date/Time End: 1988-03-15T11:00:00 * Elevation: -1301.0 m * Penetration: 225.1 m * Recovery: 190.15 m * Location: South Indian Ridge, South Indian Ocean * Campaign: Leg120 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 25 cores; 225.1 m cored; 0 m drilled; 84.5 % recovery