| Budget Amount *help |
¥2,910,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
Oligocene to Early Miocene floras prior to the tectonic episode of the Japan Sea opening are studied in their compositional and chronostratigraphical changes, together with paleoclimatic analysis of these floras based on leaf physiognomic characters. Field surveys and fossil collections are made in Akita, Fukushima, Gifu, Inland region and northern Kyushu, in addition of re-examination of plant megafossil collections and three radiometric datings in Fukushima area. Brief results are as follows:
1) "Oligocene" floras are divided into two types, Late Eocene to Early Oligocene and Late Oligocne floras. Although climatic fluctuation are evident in each floral type, these floras represent a modernized, warm-temperate flora since the Middle Eocene thermal maximum.
2) Early Miocene floras are divided into the older, temperate Aniai-type and younger, warmer Daijima-type floras. The shift from the Aniai-type to Daijima-type occurs ca. 20 Ma. Among the Daijima-type floras, those in 20 Ma to 17 Ma are characterized by Fagus and many other deciduous dicots, accompanied by many deciduous elements of Daijima type, such as Comptonia, Liquidambar, Parrotia and Quercus miovariabilis, differing the typical Daijima-type around 16 Ma.
3) Latitudinal and longitudinal (from inland to maritime areas) change in each Early Miocene flora is analyzed on the basis of the floral composition and leaf physiognomic character. Apart from latitudinal changes in the Aniai-and Daijima-type floras, the longitudinal change is apparent in the Aniai-type floras. The evidence reveals the paleogeographic changes prior to the tectonic episode of the opening of the Japan Sea in ca. 16 Ma.
4) Although these floral and climatic shifts involve the local tectonic episode, they also represent a global paleoclimatic evolution.
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