Biostratigraphy and Systematic Description of Benthic Foraminifers from Mid-Cretaceous Shallow-Water Carbonate Platform Sediments at Sites 878 and 879 (MIT and Takuyo-Daisan Guyots)

Abstract

Fourteen species of benthic foraminifers from Aptian and Albian shallow-water carbonates covering MIT and Takuyo-Daisan Guyots are identified and a new species, Cuneolina sliteri, is described. Carbonate platform microfaunas are subdivided into seven benthic foraminifer assemblages. On MIT Guyot, there is a 700-m-thick, probably complete section of Aptian-Albian, but the latest Albian faunal assemblage (Assemblage 0) is missing, indicating that platform growth ceased probably earlier at MIT than on the Takuyo-Daisan carbonate platform. On the other hand, the carbonate cover of Takuyo-Daisan Guyot is thinner (around 200 m), and a part of the Albian sequence is probably missing. Carbonate environments are extended from open-marine and wave-exposed deposits to lagoonal and restricted environments. Rising sea level is indicated by the presence of abundant orbitolinids in lagoonal settings.