グローバル気候変動と新第三紀の終わり／第四紀の始まり：石灰質ナンノ化石層序から

Abstract

We describe in detail the late Pliocene to Quaternary paleoenvironmental change associated with the newly defined Pliocene/Pleistocene boundary based on calcareous nannofossil biostratigraphy. The period from . Ma to . Ma just prior to Datum plane A, is characterized by warm water conditions named mid-Pliocene Golden age. In contrast, the paleoenvironment was drastically changed to increase of the ice sheet in the Arctic Ocean at . Ma (climate crash) which is caused by closure of the Central American Sea Way. The Quaternary style biogeography of calcareous nannoplankton and planktic foraminifer, and the ocean current system flowing from the Bering straight through the Arctic Ocean to the East Greenland Sea, were established at this time. This indicates that the main Quaternary style climate system was completed at . Ma as a response to the emergence of the Isthmus of Panama.

High‐resolution upper Pliocene to Pleistocene calcareous nannofossil biostratigraphy in Ocean Drilling Program Hole 1146A in the South China Sea

“…In this study, the datum occurs slightly below MIS12 of the BOI stratigraphy. This correlation is in good agreement with other studies (Sato et al, 2009(Sato et al, , 2012; Figure 5).…”

“…Therefore, we consider that the actual FO of this species is likely located between 33.58-70.53 mbsf, which is correlated to Marine Isotope Stage 12 (MIS12)-MIS6 of the benthic foraminifera oxygen isotope record of Uvigerina peregrina and Cibicides wuellerstorfi at ODP Site 1146 (Clemens & Prell, 2003; hereafter called the BOI stratigraphy) (Figure 5). This interpretation is not inconsistent with the FO of E. huxleyi in MIS8 (Thierstein et al, 1977) as confirmed by numerous studies (Raffi et al, 2006;Sato et al, 2012).…”

“…This is because two of the events (FO of E. huxleyi and LO of C. macintyrei) were not in the correct chronological order. We used the numerical ages assigned by Raffi et al (2006) and Sato et al (2012) (Table 2). The age-depth curves indicate a wide range of sedimentation rates from 0.8 to 16.2 cm/ky.…”

Bulk sediment mineralogy of gas hydrate reservoir at the East Nankai offshore production test site

“…Such a fossil coccolith assemblage indicates the depositional age of the gas hydrate-hosted sediments between 0.45 and 0.85 Ma (cf. Sato et al, 2012).…”

Paleomagnetic study of Plio-Pleistocene sediments in the concentrated deformation zone along the eastern margin of the Japan Sea

“…Names of key tuff (tephra) beds follow Matsui (1981). The geomagnetic polarity time scale is after Gradstein et al (2012) and the calcareous nannofossil datum (CND) planes are from Sato et al (2012). Numerical ages for individual tuff beds in the ageedepth diagram were calculated from the sedimentation rate curve.…”