哺乳動物化石の<14>^C年代測定と<13>^Cによる環境変動の解明 : 野尻湖ナウマンゾウ・オオツノシカ,関東地方ニホンシカを中心として

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Radiocarbin (^<14>C) and ^<13>C (Stable carbon isotope ; δ^<13>C) were determined for collagens of Naumann's elephant (Palaeoloxodon naumanni) and Yabe's giant deer (Sinomegaceros yabei) fossils from the Upper Pleistocene Nojiriko Formation and Sika deer (Cervus nippon) fossils from the Holocene Shellmounds of the Kantoh Plains. ^<14>C measurement of collagens extracted from mammal molar teeth, tusks, bones and horns has been done by Tandetron Accelerator Mass Spectrometer at the Dating and Materials Research Center, Nagoya University, Nagoya, Japan. Collagens were extracted from fossil samples by pretreatment and HCl-demi-neralization following to gelatinization process, and two kinds of collagens, HCl-soluble and -insoluble gelatin collagen, can be obtained. The two kinds of collagens extracted from the same sample coincide well for respective values of C/N ratio, δ^<13>C and radiocarbon age. The both collagens, therefore, can be used for the radiocarbon age determination and the ^<13>C-environmental analysis. The radiocarbon age of well-preserved molar, tusk and horn samples containing more than 0.7% (C/N rations of these samples show 3.0 to 3.9 without exception) closely coincides with that of wood fossils from the same horizon. On the other hand for the poorly preserved collagens containing less than 0.7% having larger C/N ratios than 4.0,the ^<14>C dating indicates the younger age in 5 to 10 thouthands years compared with that of wood fossils which is well preserved, showing generally reliable ^<14>C age. So it can be said that (1) most molars of Naumann's elephant fossils and most horns of Yabe's deer fossils are reliable for the ^<14>C age determination, resulting in rasonable ^<14>C ages, (2) all the tusks of elephant samples and bones of deer samples are not reliable, showing too young ages, and (3) in the case of Sika deer (Cervus nippon) fossils from the Holcene, all and both horns and bones are well-preserved to determine the ^<14>C age. Using only well-preserved mammal molar, horn and bone samples their ^<14>C ages and δ^<13>C values have been analysed and the following results were obtained in the present study. For Nojiriko samples, (1) The ^<14>C ages of Naumann's elephant and deer fossils range from 50×10^3 to 35×10^3 Yr.BP. (2) Domestic stone impliments belonging to the paleolithic man occur in the Nojiriko formation where the Naumann's elephant and deer fossils can be found. Therefore, it can be concluded from the ^<14>C ages of mammal fossils that the paleolithic man so called "Nojiriko man" is not a Neanthropic man (Neoanthrope ; Homo sapiens sapiens) but a Paleo-man (Paleoanthrope ; Homo sapiens neanderthalensis). (3) A rising trend of the atmospheric temperature from 50 thousands to 35 thousands years B.P. could be proved by δ^<13>C measurements and ^<14>C ages of the collagens extracted from the Naumann's elephant and deer fossils. This temperature-rising trend corresponds to a temterature increase of "GLACIAL STADIAL" to "INTERGLACIAL" during the last Glacial Age, the WURM Glacial Age. For the Kantoh Plain samples. (1)The ^<14>C ages of Sika deer (Cervus nippon) fossils range from 5,090 Yr, B.P. to 2,820 Yr.B.P. (2) A dropping trend of the temperature could be found from 4,000 to 3,500 Yr.B.P. in the Kantoh Plains based on δ^<13>C measurements and ^<14>C ages of the collagens from Sika deer fossils.
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哺乳動物化石の<14>^C年代測定と<13>^Cによる環境変動の解明 : 野尻湖ナウマンゾウ・オオツノシカ,関東地方ニホンシカを中心として

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