• The Journal of the Petrological Society of Korea
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• v.18 no.3
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• pp.211-221
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• 2009

This study illustrates the relationship between the petrographic characteristics of micrographic granite and the topographic features around Ijin-ri. Light-brown to light- gray granite is composed of intergrown fine-grained quartz + orthoclase, displaying micrographic textures. Miarolitic cavities are abundant. Many micro-landforms including tor, tafoni, and gnamma occurred in the micrographic granite of the study area. Tafoni is dominant in the north and gnamma is dominant in south. From our study of the occurrence and textural properties, two alteration zones were clearly identified; one is an external zone (A) characterized by abundant of small sized miarolitic cavities and the other is an internal zone (B) having them less than zone A. The former is dominant in north, and the latter is dominant in south. Particular geomorphologic features such as fluting cores and raised rims are present in the Ijin-ri area. This suggests that development of miarolitic cavities played an important role in the formation of the various geomorphologic features. Consequently, the petrogenesis of the micrographic granite is related to geomorphologic features in the external zone typified by abundant tafoni such as the tiger rock, and the formation of a platform as micro-landforms is influenced by thetextural differences of host rock in the internal zone.

• Economic and Environmental Geology
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• v.49 no.6
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• pp.417-432
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• 2016

It was firstly revealed in this research that the marine terrace of the Ijin-ri (Bukpyung-myeon, Haenam-gun) was formed during the last interglacial (Marine Isotope Stage 5e; MIS 5e). The marine terrace totally ranging from 4.8 m (asl) to 8.8 m (asl) is subdivided into 4 units; Unit I ranges 4.8-5.3 m, unit II ranges 5.3-6.9 m, unit III ranges 6.9-8.3 m, and unit IV ranges 8.3-8.8 m. Strong evidences that units II and III were formed during MIS5e were obtained based on OSL dating, the physical characterizations such as particle size distribution, magnetic susceptibility and water content, principal element and trace element analyses, and quantitative clay mineral analysis for samples at the 30 cm intervals. The rounded gravels on the marine terrace are regarded to be originated from the clastic materials transported directly from the surrounding mountains toward the marine and abraded in the coastal area, without any fluvial processes. During the warmest period (125k, unit II), the increase in rainfall, along with the rapid rise in sea level, was likely caused the high amount of clastic materials transported to the upper part of the beach. As a result of comparing clay mineral ratios of study site with those derived from sediments of either tidal flats, or the Yellow Sea, it is interpreted that the sediments of study site were influenced from the marine. The results will be used to investigate the hydrological activity and sedimentary environment during the high sea level in the past.