Oberhänsli, Hedi; Heinze, Peter-M; Diester-Haass, Lieselotte; Wefer, Gerold (1990): Component composition and benthic foraminifera in sediments of ODP Leg 112. PANGAEA, https://doi.org/10.1594/PANGAEA.753583, Supplement to: Oberhänsli, H et al. (1990): Upwelling off Peru during the last 430,000 yr and its relationship to the bottom-water environment, as deduced from coarse grain-size distributions and analyses of benthic foraminifers at Holes 679D, 680B, and 681B, Leg 112. In: Suess, E; von Huene, R; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 112, 369-390, https://doi.org/10.2973/odp.proc.sr.112.166.1990
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Indicators of surface-water productivity and bottom-water oxygenation have been studied for the age interval from the latest Pleistocene to the Holocene at three holes (679D, 680B, and 68IB) located in the center and at the edges of an upwelling cell at approximately 11°S on the Peruvian continental margin. Upwelling activity was maximal at this latitude during d18O Stages 1 (lower part), 3, the upper part of 5, the lower part of 6, and 7, as documented by high diatom abundance. During these time intervals, the bottom water was poorly oxygenated, as documented by low diversity benthic foraminiferal assemblages that are dominated by B. seminuda s.l. Both surface- and bottom-water-circulation patterns appear to have changed rapidly over short time intervals. Due to changes in surface circulation, the intensity of upwelling decreased, thereby decreasing the concentration of nutrients, and reducing the supply of organic matter to the bottom. Radiolarians became more abundant in the surface waters, and the bottom-water environment was less depleted in oxygen, allowing for the establishment of more diverse benthic foraminiferal assemblages. Surface-water productivity was probably minimal during the early part of d18O Stages 5 and 9, as indicated by the increased abundance of planktonic foraminifers and pteropods and their subsequent preservation.
Median Latitude: -11.047098 * Median Longitude: -78.092666 * South-bound Latitude: -11.065000 * West-bound Longitude: -78.272170 * North-bound Latitude: -10.976660 * East-bound Longitude: -77.957670
Date/Time Start: 1986-11-01T12:45:00 * Date/Time End: 1986-11-08T13:15:00
112-679D * Latitude: -11.063830 * Longitude: -78.272170 * Date/Time Start: 1986-11-01T12:45:00 * Date/Time End: 1986-11-02T13:15:00 * Elevation: -462.0 m * Penetration: 245.4 m * Recovery: 116.03 m * Location: South Pacific Ocean * Campaign: Leg112 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 27 cores; 245.2 m cored; 0 m drilled; 47.3 % recovery
112-680B * Latitude: -11.065000 * Longitude: -78.077830 * Date/Time Start: 1986-11-05T20:30:00 * Date/Time End: 1986-11-06T14:30:00 * Elevation: -273.0 m * Penetration: 195.5 m * Recovery: 98.45 m * Location: South Pacific Ocean * Campaign: Leg112 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 22 cores; 195.5 m cored; 0 m drilled; 50.4 % recovery
112-681B * Latitude: -10.976660 * Longitude: -77.957670 * Date/Time Start: 1986-11-08T00:00:00 * Date/Time End: 1986-11-08T13:15:00 * Elevation: -162.0 m * Penetration: 143.5 m * Recovery: 97.3 m * Location: South Pacific Ocean * Campaign: Leg112 * Basis: Joides Resolution * Device: Drilling/drill rig (DRILL) * Comment: 16 cores; 143.5 m cored; 0 m drilled; 67.8 % recovery