Unknown
PANGAEA
In:
Supplement to: Hsü, Kenneth J; Percival, Stephen F Jr; Wright, Ramil; Petersen, Nikolai P (1984): Numerical ages of magnetostratigraphically calibrated biostratigraphic zones. In: Hsü, KJ; LaBrecque, JL; et al. (eds.), Initial Reports of the Deep Sea Drilling Project (U.S. Govt. Printing Office), 73, 623-635, https://doi.org/10.2973/dsdp.proc.73.124.1984
Publication Date:
2023-06-27
Description:
Most Cenozoic nannofossil and many foraminiferal zonal boundaries have been accurately determined and magnetostratigraphically calibrated at five Leg 73 boreholes. The numerical ages of the boundaries were computed by assuming a linear seafloor spreading rate and a radiometric age of 66.5 m.y. for the Cretaceous/Tertiary boundary. Alternative magnetostratigraphic ages (given below in parentheses) were obtained by adopting a 63.5 m.y. age for the Cenozoic. Our data confirm previous determinations of the Pleistocene/Pliocene boundary at 1.8 (1.7) m.y. and of the Pliocene/ Miocene boundary at 5.1 (5.0) m.y. The Miocene/Oligocene boundary is placed within Chron C-6C and has a magnetostratigraphic age of 23.8 to 24.0 (22.7 to 22.9) m.y. The Oligocene/Eocene boundary is also very precisely located within Chron C-13-R, with a magnetostratigraphic age of 37.1 to 37.2 (35.5 to 35.6) m.y. The Eocene/Paleocene boundary should be located within an uncored interval of Chron C-24 and have a magnetostratigraphic age of 59.0 (55.4) +/- 0.2 m.y.
The general accord of the magnetostratigraphic and radiometric ages supports the hypothesis that the seafloor spreading rate was linear during the Cenozoic. Two possible exceptions are noted: the middle Miocene radiometric ages are a few million years older, and the early Eocene radiometric ages are several million years younger, than the corresponding magnetostratigraphic ages.
Keywords:
73-519; 73-521; 73-521A; 73-522; 73-522A; 73-523; 73-524; Deep Sea Drilling Project; DRILL; Drilling/drill rig; DSDP; Glomar Challenger; Leg73; South Atlantic/CANYON; South Atlantic/HILL; South Atlantic/PLATEAU; South Atlantic/RIDGE
Type:
Dataset
Format:
application/zip, 3 datasets
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