Diversity of cold-adapted ciliates from glacier snow and cryoconite in Arctic region

第2回極域科学シンポジウム/第33回極域生物シンポジウム 11月18日（金） 統計数理研究所 3階セミナー室

Periodicities of palaeo-climatic records extracted from the Dome Fuji deep core

The Antarctic ice sheet preserves palaeo-climate information in the form of physical and chemical stratigraphy. A deep ice core was continuously drilled down to a depth of 2503m at Dome Fuji Station, East Dronning Maud Land, Antarctica, during the 1993-97 JARE inland operations. A time scale for the Dome Fuji core is calculated from past accumulation rates and an ice flow model. A depth-age profile was obtained for the past 320kyr back in time. The obtained palaeo-temperature profile shows the past three glacial and interglacial periods. The power spectrum for oxygen isotope variation for 320kyr shows three dominant cycles of 107kyr, 40kyr and 21kyr. Each of these three cycles is similar to Milankovitch cycles. Moving-window spectrum analysis, using a 130kyr window stepped by 10kyr over the past 320kyr, found these main cycles in every age. Variations of other chemical concentrations were also recovered from the Dome Fuji ice core, and are inversely correlated to the temperature profile. Concentrations of terrestrial and marine origin substances are high in glacial periods, and low in interglacial periods. Over the past 320kyr, the dominant periodicities of temperature were also detected in almost all chemical records

Dating of the Dome Fuji, Antarctica deep ice core (scientific paper)

The Antarctic ice sheet preserves paleo-climate information in the form of physical and chemical stratigraphy. A deep ice core was continuously drilled down to a depth of 2,503 m at Dome Fuji station, East Dronning Maud Land, Antarctica, during the 1993-97 JARE inland operations. Oxygen isotope measurements were conducted on 7 to 50 cm-long ice core samples selected from the entire core depth. A time scale for the Dome Fuji core is calculated from past accumulation rates and an ice flow model. Past accumulation rates were converted from oxygen isotope values by using an empirical equation obtained in the Dome Fuji area. A steady-state flow model was preciously developed for a time scale calculation of the Summit ice core, Greenland. Using reference depth points from volcanic signals and annual layer thickness values measured on the Dome Fuji core allows for tuning of the calculated time scale. A depth-age profile was obtained for the past 320 kyr. The obtained paleo-temperature profile shows the characteristics of the past three glacial and interglacial periods. The power spectrum of ƒÂ18O change over an interval of 320 kyr reveals three dominant cycles. The paleo-temperature profile coincides quite well with the Vostok ice core data in general but not in detail, suggesting that further studies are needed both for chronological investigations and a multi-factor, cross-correlation analysis between deep ice cores for climatological understanding