Eocene-Miocene high latitude biostratigraphy

Abstract

Studies of high-latitude planktonic foraminiferal faunas indicate that certain biostratigraphic problems may be resolved by the application of bioevents among the three microperforate families, Guembelitriidae, Chiloguembelinidae and Tenuitellidae. With the aid of the scanning electron microscope, these small tests appear to be useful stratigraphic markers in the condensed sequences of deep-sea cores, where their evolution can be correlated with magnetostratigraphy.In the early-mid-Eocene, the Jenkinsina-Cassigerinelloita lineage assists the recognition of zones based on the larger, muricate Acarinina. Four zones are proposed in a revised lineage zonation of the tenuitellids, presented as a complementary biostratigraphic scheme for differentiating the Eocene-Oligocene boundary interval in high latitudes: (1) the Praetenuitella insolita Zone in the late Eocene; (2) the Tenuitella gemma Zone in the early Oligocene; (3) the Tenuitella munda Zone in the mid-Oligocene; (4) the Tenuitellinata angustiumbilicata Zone in the late Oligocene.

Eocene to Miocene magnetostratigraphy, biostratigraphy, and chemostratigraphy at ODP Site 1090 (sub-Antarctic South Atlantic)

“…The FAD of Tenuitella gemma is recorded at Site 1090 just above, or in coincidence with, the exit of G. index. According to Radford and Li (1993), Tenuitella evolved from . This bioevent occurs in the older half of C13r at Site 1090.…”