Magmatic activities have invaded the Iran Plateau from the north to south during the subducting of the Neotethys oceanic lithosphere beneath western Iran since the Cretaceous. The magmatic activities made a large potential for generation of the ore deposits such as gold, copper, and iron in the Iran Plateau. The relation of the ore deposits with their host magmatic rocks and the sources of the deposits are not well understood. Therefore, new methods and age determination are more important to elucidate the geodynamic and tectonic setting of magmatic activities. The chemical compositions and isotope ratios of young volcanic rocks in NW show the source rocks have been affected by the subducted oceanic flux. The important key to undertenant the recycling of pelagic sediments in the subduction zone is the Large Ion Lithophile elements such as Li, B, and Be. Actually, due to the high concentration of these elements in the continental crust, it would be difficult to know whether the enrichment of LILE in magma occurred by the filtrations of magma from the continental crust or by recycling of pelagic sediment in the subduction zone. 10Be is the key to solving this problem, especially for the young volcanic rocks with less than 10 Ma. 10Be is a cosmogenic isotope, formed in the Earth's atmosphere mainly by cosmic ray spallation of nitrogen and oxygen. This isotope is concentrated in the young pelagic sediments in the ocean. During the oceanic lithosphere subducting, due to the strong extensional regime, the horst and graben system develop near the trench zone and the grabens, which are more suitable to precipitate the young sediments rich in 10Be. The sediments are dragged down into the mantle beneath the continental crust, during the oceanic lithosphere subduction. To examine this process, we determined 10Be values for a large number of young volcanic rocks in NW Iran. The data show the different 10Be concentrations ranging from the very low to high value and it infers the involvement of pelagic sediments in the genesis of the young magmatic activities in NW Iran. Therefore, 10Be and 10Be/9Be ratios are expected to be prevailing factors in understanding the magmatic evolution in the active margins such as continental margin and Island arc tectonic regime in a subduction zone. 17PM-05S solicited Multi-decadal climate variability as a driver of human history Takeshi NAKATSUKA Recently, oxygen isotopic studies on tree-ring cellulose in central Japan have elucidated past changes in summer climate over East Asia very precisely during last several millennia at annual time resolution. By comparing the paleoclimate time-series with numerous historical and archaeological evidence in Japan and surrounding countries, I have found remarkable relationships between climate variation and human history at various time scales from inter-annual to multi-centennial ones because summer climate directly influences yield of crops, such as rice, a main food of Japanese people from 3000 years ago. Especially when multi-decadal climate variability was enhanced, past human societies were suffering from many troubles, such as famines and wars, and obliged to change the social system to overcome the difficult condition, probably because the enhanced multi-decadal climate variation must have caused serious imbalance between human population and food production. During last a few millennia, the multi-decadal climate variability was enhanced intermittently approximately at 400 years intervals, apparently resulting in political regime shifts in Japan and dynasty cycles in China, but the fundamental mechanisms why the multi-decadal variation is enhanced have not been clarified yet. Possible candidates are the changes in frequency of volcanic eruptions and the changes in solar cycles. In this presentation, I will introduce the past climate-history relationship in Japan and world using up to date dendroclimatological datasets, with special foci on multi-decadal climat
