HR: 1340h
AN: PP13C-1418    [Abstracts]
TI: Linkage between human activity and environments during the mid-Holocene Hypsithermal climatic interval - Changes in human activity at the Sannai-Maruyama ruins in Japan -
AU: * KAWAHATA, H
EM: kawahata@ori.u-tokyo.ac.jp
AF: Graduate School of Frontier Sciences and Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo, 164-8639, Japan
AU: * KAWAHATA, H
EM: kawahata@ori.u-tokyo.ac.jp
AF: Graduate School of Science, Tohoku University, Higashi-1, Tsukuba, Ibaraki, 305-8567, Japan
AU: YAMAMOTO, H
AF: Graduate School of Science, Tohoku University, Higashi-1, Tsukuba, Ibaraki, 305-8567, Japan
AU: OHKUSHI, K
AF: Kobe University, 3-11 Tsuru-kou, Nada, Kobe, 657-8501, Japan
AU: YOKOYAMA, Y
AF: Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Tokyo, 113-0033, Japan
AU: KIMOTO, K
AF: Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2- 15, Yokosuka, 237-0061, Japan
AU: YAMAOKA, K
AF: Graduate School of Frontier Sciences and Ocean Research Institute, The University of Tokyo, 1-15-1 Minamidai, Nakano, Tokyo, 164-8639, Japan
AU: YAMAOKA, K
AF: Graduate School of Science, Tohoku University, Higashi-1, Tsukuba, Ibaraki, 305-8567, Japan
AB: The Sannai-Maruyama site is one of the famous and best-archaeologically researched sites for the ruins in Japan during mid-Holocene because of the greatest, well-developed and long-term existing community during the mid-Holocene (mid-Jomon era). According to archeological researches, the Jomon people had inhabited at the Sannai-Maruyama ruins from 5.9-4.2 +/- 0.1 cal. kyr. B.P.. However, little is know about the continuous record on terrestrial and marine environments around the site. Core KT05-7 PC-02, located only 20 km from the ruin, was recovered in Mutsu Bay in order to reconstruct high-resolutonal time-series records, including quantitative sea surface temperatures (SSTs). The C37 alkenone-SSTs showed definite fluctuation with four high SST periods (8.4-7.9, 7.0-5.9, 5.1-4.1 and 2.3-1.4 cal. kyr B.P.) and with low SST periods (-8.4, 7.9-7.0, 5.9-5.1 and 4.1- 2.3 cal. kyr B.P.), which have periodically fluctuated in 1.0-2.0 kyr intervals with about 1.5-2.0 degree amplitude. Based upon contents of TOC (total organic carbon) and C37 alkenone with TOC/TN (TOC/total nitrogen) ratios indicate that marine biogenic production was low before 7.0 cal. kyr B.P. and definitely elevated between 5.9 and 4.0 cal. kyr B.P. due to the stronger vertical mixing. During the community-prospering periods (between 5.9 and 4.2 +/- 0.1 cal. kyr B.P.), the climate had been improved. High relative abundance of both Castanea and Quercus subgen. Cyclobalanopsis pollens supports the interpretation that the local climate was optimum for human community, which would increase the population. Some discrepancy between warm terrestrial climate and low C37 alkenone-SST between 5.9-5.1 cal. kyr B.P. might be attributed to water column structure different from the modern condition in the Tsugaru Strait. These lines of evidence suggest that high production of marine products such as fishes and shells under terrestrial warm climate at 5.9 cal. kyr B.P. resulted in the establishment of the human community at the Sannai-maruyama site and that sudden marine and terrestrial cooling, evidence by C37 alkenone-SST (by 2 degree) and pollen floras, was responsible for reduced terrestrial food supply, which could have caused the people to give up the Sannai-Maruyama ruin at 4.1 +/- 0.1 cal. kyr B.P.. This timing is very consistent with the decline timing (around 4.0-4.3 within error) of several civilization such as the north Mesopotamian and the Yangtze river civilization. A temperature rise by ~2 degree in the future global warming in this century may be enough for giving a great impact on certain areas of the human community, especially agriculture division, even at contemporary society.
DE: 1637 Regional climate change
DE: 4914 Continental climate records
DE: 4940 Isotopic stage
DE: 4954 Sea surface temperature
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting