Title: Organic geochemistry and biogeochemistry in sedimentology
Abstract: Study of sedimentary organic matter in the latter half of 20th century had been greatly promoted by fossil fuel industry. As a result, various organic geochemical indicators to reconstruct thermal/burial history and depositional environment of the sedimentary rock were established. Computer modeling of basin evolution and oil/gas accumulation with organic geochemical indicators is now a matter of routine for petroleum exploration. The great leap forward in organic geochemistry relevant to petroleum exploration seems to have come to an end.In addition to a problem of energy resource exhaustion, another our great concern is a rapid change of global climate. Organic-rich sediments are important not only as energy resources but also as a huge carbon reservoir in global climate system. The elucidation of temporal and spatial global climate change rests upon organic geochemical/biogeo-chemical study of sediments. Researches related to carbon-burial fluxes and to the formation and preservation of biologically controlled paleoenvironmental records in sea-floor sediments have been extensively conducted in the last few decades. Development of paleoenvironmental proxies, reconstruction of ecological system by molecular biomarkers, temporal and spatial variation of fluxes of biogenic materials and so on are also researches in area of organic geochemical and biogeochemical study of sediments. This type of research field is recently called “Biogeochemical Sedimentology”.Problems of energy resource exhaustion and global climate change are still driving forces to promote development of the study of organic matter in sediments and sedimentary rocks. Organic and biogeochemical Sedimentology takes responsibility for development of non-conventional energy resources such as methane gas hydrates. Microbial activity in sediments plays an important role for carbon circulation and the formation of gas hydrate. The Earth system is based upon the Earth and Life's interaction, which always plays an important role to induce evolution of biosphere. Development of organic and biogeochemical sedimentology in this new century will increasingly depend on collaborations with biology. Organic and Biogeochemical sedimentology will contribute to understanding the Earth system and to promote neo-science of natural history for a new view of nature in the 21st century.