27 resultados para p11
em Publishing Network for Geoscientific
Resumo:
We present here oxygen and carbon isotopic records of Eocene to Oligocene benthic foraminifera from two Bay of Biscay Deep Sea Drilling Project (DSDP) sites (119 and 401). d18O of benthic foraminifera increases 1.9 per mil from a middle Eocene minimum (Zones P10-P11) to an earliest Oligocene maximum (Zone NP21). Approximately 1.4 per mil of the increase in benthic foraminiferal d18O occurs during the late Eocene to earliest Oligocene (Zones P15/16-NP21). Previous results from other North Atlantic DSDP sites (400A and 398) have significantly lower d18O values of benthic foraminifera, some by as much as 2 per mil (Vergnaud-Grazzini et al., 1978; 1989, doi:10.2973/dsdp.proc.48.119.1979; Vergnaud-Grazzini, 1979, doi:10.2973/dsdp.proc.47-2.117.1979 ). We believe that these differences result from diagenetic alteration of the sediments in the deeper-buried Sites 400A and 398.
Resumo:
Twenty-eight core catcher samples were provided to the author by the shipboard party for evaluation of fossil diatoms. Samples are from Ocean Drilling Program Leg 207 Holes 1257A, 1257B, 1257C, and 1258A. The samples range from 50 to 112 meters below the seafloor (mbsf) at Site 1257 and from ~22 to 60 mbsf at Site 1258. At Site 1257, samples range in age from middle Eocene (foraminifer Zone P14-13) to late Paleocene (mid-foraminifer Zone P4). At Site 1258, the samples range from middle Eocene (foraminifer Zone P11) to early Eocene (foraminifer Zone P5) according to the preliminary biostratigraphic reports (Erbacher, Mosher, Malone, et al., 2004, doi:10.2973/odp.proc.ir.207.2004). All samples were processed at Florida State University Antarctic Research Facility. Treatment included acidization and sieving through stacked 38- and 63-µm sieves. Strew slides were made from each fraction and the catcher pan. A Zeiss Photoscope II microscope was used for examination of the prepared slides. Samples from Holes 1257A, 1257B, and 1257C showed that most of the samples are barren of siliceous microfossils. Only a few radiolarians and fragments of radiolarians were observed.