Summary of Past and Present Research Activities

• My primary research fields lie in metamorphic geology and petrology.
  The on-going projects focus on field-oriented work dealing with Phanerozoic fold belts and Precambrian basement rocks in South Korea. Other projects are primarily concerned with tectonic correlation of the Korean Peninsula with China and Japan, and low-temperature metamorphism in the Barton Peninsula, Antarctica. My previous research activities include: (1) experimental syntheses of calcic and sodic amphiboles, clinochlore, zeolites, and prehnite, using cold-seal and piston-cylinder apparatus; and (2) phase equilibria and facies transitions in low-temperature metabasites. In the following, current research activities dealing with various metamorphic terranes in Korea are briefly described.

• Imjingang Belt: The Imjingang Belt in central part of the Korean Peninsula is often cited as the candidate for the eastward continuation of the Triassic Chinese collision belt. My students and I have been working in this belt since 1992, and reported for the first time on the occurrences of the highest pressure (ca. 10~12 kbar) metamorphic rocks ever recorded in Korea. We have been focusing our research not only to better define metamorphic temperatures, pressures and fluid compositions but also to determine the peak metamorphic and cooling ages using various radiogenic isotope systems: e.g., U-Pb (in collaboration with Dr. Wan Yusheng at Beijing SHRIMP center, China) and ⁴⁰Ar/³⁹Ar (with Prof. C.-H. Lo at Taiwan National University, R.O.C.). We also used the cathodoluminescence technique for delineating the complex growth history of plagioclase in metapelites. Further studies dealing with temporal relationship between garnet, staurolite and kyanite porphyroblasts and regional deformation events are in progress.

• Ogcheon Belt: This belt is another Phanerozoic metamorphic fold belt in Korea, and its evolutionary history is still ambiguous primarily because of the lack of tectonometamorphic and especially geochronologic data. Major goal of our research is to define metamorphic P-T-time path of the Ogcheon belt by applying modern petrologic techniques and various isotopic systems. Among the important observations we have made are: (1) This belt has experienced two regional metamorphic episodes at Late Carboniferous-Early Permian and Late Triassic times, and finally thermal metamorphism in Jurassic; (2) Early regional metamorphism reaching ca. 600oC and 8 kbar defines a typical Barrovian sequence that can be accounted for by crustal thickening during the intra-continental collision process; and (3) P-T condition of the Triassic regional-thermal metamorphism is 350-500oC and 1-3 kbar primarily based on the fluid inclusion study. In addition, for investigating mineral textures and reactions on the nanometer scale with transmission electron microscopy, we are collaborating with Prof. Jung-Ho Ahn at Chungbuk National University, Korea.

• Gyeonggi and Yeongnam Massifs: These two Precambrian massifs, comprising the basement rocks of the Korean Peninsula, were thought to have experienced a typical low-pressure high-temperature metamorphism. However, we have documented the occurrences of relict kyanite crystals not only in the cover rock sequences but also in the basement rocks of the Gyeonggi massif, suggesting a crustal thickening process prior to regional low-pressure metamorphism. Further work to constrain temporal relationships of this collisional orogeny is in progress, primarily using the SHRIMP technique for dating zircon grains (in collaboration with Dr. Wan Yusheng at Beijing SHRIMP center, China and Dr. M. Wingate at Univ. of Western Australia). Currently we are carrying out two projects: (1) P-T-t relationship of high-pressure metamorphic rocks (garnet amphibolites and garnetite) in western Gyeonggi massif; and (2) Paleoproterozoic tectonometamorphic evolution of the Taebaegsan gneiss complex in the northeastern Yeongnam massif.