Isaza, Carolina et al. (2003): Late Maastrichtian Foraminifera population dynamics and their relationship to parallel stable isotopic measurements

Leg/Site/Hole:
ODP 171B
ODP 171B 1050
Identifier:
2005-043740
georefid

Creator:
Isaza, Carolina
University of Missouri, Department of Geological Sciences, Columbia, MO, United States
author

MacLeod, Ken
Smithsonian Institution, United States
author

Huber, Brian T.
author

Identification:
Late Maastrichtian Foraminifera population dynamics and their relationship to parallel stable isotopic measurements
2003
In: Anonymous, Geological Society of America, 2003 annual meeting
Geological Society of America (GSA), Boulder, CO, United States
35
6
254
By measuring stable isotopic ratios in parallel with foraminiferal population counts across cyclic intervals in the upper Maastrichtian of Ocean Drilling Program Site 1050, we have tested conclusions regarding the species-level paleoecology and short term oceanographic variability within a greenhouse ocean. During the Maastrichtian Site 1050 was located at approximately 30 degrees N latitude in the western North Atlantic. The Maastrichtian section shows dark-light color alternations that have been attributed to precessional cycles. In a previous study across the most prominent Maastrichtian cycles, light colored intervals were found to be associated with relatively high productivity, relatively cool temperatures, and higher relatively abundances of Heterolix spp. and Globigerinelloides spp.; darker intervals were associated with relatively low productivity, relatively warm temperatures, and higher relative abundances of Globotruncana spp. and Pseudoguembelina spp. Preliminary results suggest these relationships break down in an interval where cyclicity is less dramatic. Across low amplitude cycles in a younger interval from the same hole, we have found that light colored intervals are associated with the highest delta (super 13) C values for Heterolix globulosa, and Rugoglobigerina rugosa consistent with high relative productivity in these intervals. However, the largest variations in delta (super 13) C values are seen in Pseudoguembelina palpebra, and these values show no apparent relationship to cyclic color changes. Further, whereas bulk carbonate and H. globulosa have delta (super 18) O values that suggest the light intervals were relatively cool, delta (super 18) O values of the presumed surface dwellers R. rugosa and P. palpebra suggest, if anything, the opposite. Finally, most taxa studied have their peak abundances in a sample from a relatively light interval, but not in all samples from light interval. These results demonstrate that neither the local water column nor planktic foraminiferal distributions responded in a consistent fashion to Milankovitch-scale forcing. With further work on this interval, we believe we will find that certain taxa were relatively abundant during either high or low productivity intervals and that the complexity seen is due in part to variation in the surface mixed layer being out of phase with variation deeper in the water column.
English
Coverage:Geographic coordinates:
North:30.0600
West:-76.1406East: -76.1406
South:30.0600

Stratigraphy; Isotope geochemistry; assemblages; Atlantic Ocean; biostratigraphy; C-13/C-12; carbon; Cretaceous; ecosystems; Foraminifera; geochemistry; Globigerinacea; Globigerinidae; Globigerinoides; Invertebrata; isotope ratios; isotopes; Leg 171B; Maestrichtian; Mesozoic; microfossils; Milankovitch theory; North Atlantic; O-18/O-16; Ocean Drilling Program; ODP Site 1050; oxygen; paleoecology; paleoenvironment; planktonic taxa; Protista; Rotaliina; Senonian; stable isotopes; Upper Cretaceous; upper Maestrichtian;

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