Silicoflagellate Stratigraphy, Deep Sea Drilling Project, Leg 36

Abstract

DSDP Leg 36 recovered abundant and well-preserved silicoflagellates in Tertiary sediments of the Falkland Plateau and the adjacent Malvinas Outer Basin. Of particular interest are the older assemblages of Paleocene (Site 327), Eocene (Site 328), and Oligocene (Sites 328 and 329) age which were recovered at relatively shallow subbottom depths (30 to 70 m) except at Site 329 where Oligocene silicoflagellates were recovered down to about 420 meters. Paleotemperature plots for a long Miocene section at Site 329 show a warming trend in the upper Miocene, consistent with previous Southern Ocean studies. Pliocene and Pleistocene paleotemperature curves could not be constructed due to the sparse flora in that interval. A new zone, the Mesocena circulus/Mesocena diodon Zone, is established for the middle to upper Miocene. The zone represents the co-occurrence of Mesocena circulus and Mesocena diodon, two species which have not been found together in other areas. Five new species and subspecies named and described are: Corbisema cuspis, Corbisema navicula constricta, Dictyocha fallacia, Distephanus crux fenestratus, and Pseudomicromarsupium gombosum.