Tentative standardized legends of metamorphic rocks for 1/200,000 scale seamless geological map of Japan

Kazuhiro Miyazaki
This paper presents tentative standardized legends of metamorphic rocks for 1/200,000scale seamless geological map of Japan. Metamorphic rocks distributed in the Japanese Islands have experienced complex processes, such as metamorphic reactions and deformations, in arc-trench system during their formation and uplift stages. As a result, these metamorphic rocks have wide variety of physical and chemical properties depending on their origins. I classified metamorphic rocks with following three
more » ... ple criteria; (1) metamorphic condition, (2) metamorphic age, (3) lithology of protolith. The classifying criterion-(1) suggests generated site of metamorphic rocks in the arc-trench system and contains integrated information about constituent minerals and texture of rocks. The classifying criterion-(2) represents similarity of generated or uplifted time of metamorphic rocks exposed in different regions. The classifying criterion-(3) shows chemical composition of rocks and is useful for showing macro structure of metamorphic belts. An application of the above-mentioned classifying criteria (1)-(3) to matrix type legend of the major metamorphic rocks in Japan reduced number of the legends to 50. In future, complex attribute of metamorphic rocks will be expressed with minimum criterion by overlaying criteria (1) and (2) on lithology of protolith which were classified into sedimentary and igneous rocks. Keywords: Standarized legends of metamorphic rocks, metamorphic condition,metamorphic age, lithology of protolith.
doi:10.9795/bullgsj.54.295 fatcat:g427lerre5bvve3cermirc3xha