Discussion On Geobiology, Biogeology And Geobiofacies

1 Geobiology and biogeology

The term ‘geobiology’ is more widely used than the term ‘biogeology’[13,14]. Although vaguely applied and mixed up at the beginning, the meaning of the two terms is now gradually alienated. However there is as yet no consen-sus concerning the difference between the two terms[15,16]. In terminology generally when ‘geo’ is used as a prefix, it means a 1st order interdisciplinary study between geoscience domain and another domain (phys-ics, chemistry), such as geophysics and geochemistry. On the other hand if ‘geology’ is used as a subject, it means a 2nd order interdisciplinary study between the 1st order discipline ‘geology’ and another discipline. Thus scope of the former term with ‘geo’ prefix covers that of the latter term. For example geophysics include studies of solid geospheres, hydrosphere, atmosphere and the solar-terrestrial space, while physical geology usually deals with studies of geological phenomena and processes[17]. Geobiology is commonly defined as an interdisciplinary study of biology and earth sciences, while biogeology is defined as an interdisciplinary study of biology and geology. As in other terminology of in-terdisciplinary geosciences, the term geobiology spans wider than the term biogeology. It covers interrelations between biosphere and all rest of the Earth’s spheres. The journal Geobiology, published by Blackwell since 2003, listed its nine domains, namely, 1) origins and evolution of life, 2) evolution of the atmosphere, hydro-sphere and biosphere, 3) the sedimentary rock record and geobiology of critical intervals, 4) paleobiology and evolutionary ecology, 5) environmental microbiology, 6) biogeochemistry and global elemental cycles, 7) mi-crobe-mineral interactions, 8) biomarkers, and 9) mo-lecular ecology and phylogenetics. The journal JGR-Biogeosciences indicates that its scope consists of biogeochemistry, biogeophysics, land-atmosphere and ecosystem interactions, biomineralization, life in ex-treme environments, astrobiology, microbial processes, geomicrobiology, and evolutionary geobiology. A large part of the scope of geobiology, such as domains 5, 6, 8, 9, is beyond that of biogeology. Explanation of geobiol-ogy in Glossary of Geology[15], namely, “the study of the biosphere, esp. through geologic time”, seems have to be expanded now, because its scope is now much beyond biosphere through geologic time. The term ‘biogeosci- ences’ defined as study of interactions between organ- isms and lithosphere, hydrosphere and atmosphere[18,19] or study spanning the interface between biology and geosciences, as expressed in the introduction of JGR-Biogeosciences, bears the same meaning of the term geobiology.

Geobiology may also be defined as a coupled system or coevolution of the earth and its biota in past, present, and future[1－3]. In biology, coevolution is defined as the mutual evolutionary influence between two species (or group). The

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