Olsson, Richard K. et al. (2000): Recovery of planktonic Foraminifera following the Cretaceous/Tertiary mass extinction

Leg/Site/Hole:
Identifier:
2002-068165
georefid

Creator:
Olsson, Richard K.
Rutgers University, Department of Geological Sciences, Piscataway, NJ, United States
author

Wright, James D.
University of Tuebingen, Federal Republic of Germany
author

Miller, Kenneth G.
author

Hemleben, Christoph
author

Identification:
Recovery of planktonic Foraminifera following the Cretaceous/Tertiary mass extinction
2000
In: Anonymous, Geological Society of America, 2000 annual meeting
Geological Society of America (GSA), Boulder, CO, United States
32
7
145
Carbon 13 values of benthic and planktonic foraminifera across the Cretaceous/Tertiary boundary (K/T) in New Jersey boreholes (ODP Legs 150X and 174AX) show the carbon isotopic shift across the K/T that indicates a reduction in oceanic primary productivity, the "Strangelove" ocean. Paleocene strata used in this study were deposited in a shelf setting (ca. 100 m paleodepth), which would have encompassed the photic zone and the deep chlorophyll maximum (DCM) layer. Carbon 13 values of Danian foraminifera are similar to the data of D'Hondt et al. (1998) that indicate organic flux to the deep ocean did not fully recover for over 3 million years. However, three observations are inconsistent with their hypothesis that organic flux recovered quickly in shallow environments. From our study on the New Jersey shelf, the overall calcium carbonate accumulation rate decreased, the mean ocean carbon 13 value did not significantly change, and the shelves did not go anoxic. The low carbon 13 values in shelf paleodepths may be due to lowered fertility and a thin DCM. Oxygen 18 values of Danian species indicate that they occupied a narrow range in the water column, suggesting a restricted DCM. The appearance of highly-efficient-feeding spinose planktonic foraminifera in the Danian may be an adaptation to these oligotrophic conditions. A marked change took place during the transition from the Danian to the upper Paleocene. The average size of planktonic foraminifera nearly doubled and the diversity of species doubled. Furthermore, oxygen 18 values show that a greater vertical range of the water column was used by individual species with shallow, intermediate, and deeper-dwelling habitats. We hypothesize that fertility of the oceans and the expansion of the DCM had returned to pre-K/T boundary levels on the shelf ca. 4 my after the extinctions and that the delay resulted either from reduced nutrient input from the continents or a different surface water mass structure.
English
Coverage:Geographic coordinates:
North:41.2100
West:-75.3500East: -73.5300
South:38.3000

Stratigraphy; adaptation; Atlantic Coastal Plain; C-13/C-12; calcium carbonate; carbon; Cenozoic; chlorophyll; Cretaceous; Danian; depositional environment; extinction; Foraminifera; habitat; Invertebrata; isotope ratios; isotopes; K-T boundary; Leg 150X; Leg 174AX; lower Paleocene; marine environment; mass extinctions; Mesozoic; microfossils; New Jersey; nutrients; O-18/O-16; Ocean Drilling Program; organic compounds; oxygen; paleo-oceanography; Paleocene; Paleogene; pigments; plankton; planktonic taxa; productivity; Protista; recovery; shallow-water environment; shelf environment; species diversity; stable isotopes; stratigraphic boundary; Tertiary; United States; Upper Cretaceous;

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