Profile
Degrees:
1992 DSc Earth Sciences, Nagoya University
1988 MSc Earth Sciences, Nagoya University
1986 BSc Earth Sciences, Nagoya University
Educations:
1978-1981: Matsusaka High School, Mie Prefecture, Japan
1981-1986: Department of Earth Sciences, Nagoya University, Japan
1986-1991: Graduate School of Earth Sciences, Nagoya University, Japan
Professional Experiences:
2006-resent Professor of Graduate School of Environmental Studies, Nagoya University
2001-2006 Associate Professor of Graduate School of Environmental Studies, Nagoya University
2000-2001 Associate Professor of School of Informatics and Sciences, Nagoya University
1993-2000 Research Associate of School of Informatics and Sciences, Nagoya University
1991-1993 Research Associate of College of General Education, Nagoya University
1990-1991 Research Fellowships of the Japan Society for the Promotion of Science for young scientists,
Honors and Awards:
1995 The Geochemical Society of Japan Award for Young Researchers
Research Interests
My major research interests are 1) evolution and diversity of early (Precambrian) life and 2) biogeochemical cycles in a river-dam system
1) Evolution and diversity of early life
––– Archean Microfossil Project––––
From the Archaean (> 3.0Ga) sedimentary succession at the Mount Grant and Mount Goldsworthy area in the northeastern Pilbara Craton, Western Australia, a diverse assemblage of carbonaceous microstructures were recently discovered and their biogenicity have been claimed from indigenousness, syngenicity, sedimentary origin of the host chert, narrow size distribution, composition (disordered carbon), evidence of flexible and/or breakable walls, apparent taphonomic features and the presence of colony-like aggregations (Sugitani et al., 2007 in Precambrian Research). This preliminary report has subsequently been tested by multidisciplinary studies. Namely, their elaborate morphologies inferred from the normal optical microscopic analyses are confirmed by reconstructed 3-D images, disputing the possibility that the elaborate structures are the results of displacement of carbonaceous matter during diagenetic silica spherulite growths (Sugitani et al., in review). Nano-scale chemical and isotopic mapping also indicate that the structures are enriched in biologically important elements such as sulfur and nitrogen as well as carbon (Oheler et al., 2008). These lines of new evidence strongly support that the fossil evidence of life is back to the Archaean. Whilst these accumulating lines of evidence supporting the biogenicity of the microstructures, there are still many problems unresolved as listed below, some of which should be answered in the context of evolution of life and environment on the early earth. 1) Preliminary classification of the putative microfossils is simply morphology-based and thus probably superficial. Obviously, their taxonomy should be established in order to interpret then in the context of phylogeny, although extraordinary diversity and complexity in morphology and occurrence hinders us from approaching the goal. 2) Many of the putative microfossils are larger than 20µm and occasionally up to 80µm in the major axis, although modern prokaryotic organisms are in general smaller than 10µm. This large size may let people remind the possibility that eukaryotic micro-organisms are involved in the putative microfossils. However, this possibility is very difficult to verify because it is at present quite equivocal whether the large structures in question are vegetative cell, spore, outer sheath of colony, or enlarged cell wall with gas or other wastes. 3) Very complex morphologies and occurrences, in general not expected to be appeared in microfossil records, are involved in the assemblage. As far as the biogenicity of “representative” types such as spheroids, films and spindles is claimed, they should be interpreted in the biological context; if not, their aboigenic origin should be proved. These subjects would be addressed to in this project.
2) Biogeochemical cycles in a river-dam system
---under construction
