• Journal of the Korean Geographical Society
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• v.38 no.4
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• pp.505-517
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• 2003

The purpose of this paper is to examine the origin of materials of sanddune in the Chungcheongnamdo. The sands consist mainly of quartz with lesser amount of feldspar and other heavy minerals. With the exception of those from the granite, the sands have a very fine texture. Another characteristic of the sand grains is the low degrees of roundness and grading which indicates that the source areas of the material are not far from the accumulating field. The rivers and streams of this region are not effective in transporting sediments for the coastal dunes. It has been recognized that the beaches and sanddunes have recently been receded as a result of the decrease in materials and the devastating actions of the breakers. The degradation process occurs most actively when the spring tides attack the beaches and foredunes. There are strata with red tint along the coastal areas of the Chungcheongnamdo which trace their origin back to the Pleistocene. From the fact that they contain little or no gravels, the strata are believed to have been the sanddunes during the last interglacial period. This fossil dunes provide part of the materials for the development of the present-day sanddunes along the coastal areas of the region.

• The Korean Journal of Petroleum Geology
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• v.6 no.1_2 s.7
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• pp.20-24
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• 1998

Expert system is one type of artificial intelligence softwares that incorporate problem-solving knowledges and experiences of human experts by use of symbolic reasoning and rules about a specific topic. In this study, an expert system, PLAYMAKER2, is used to interpret sedimentary facies and depositional settings of the sedimentary sequence. The original version of the expert system, PLAYMAKER, was developed in University of South Carolina in 1990, and modified into the present PLAYMAKER2 with some changes in the knowledge-base of the previous system. The late Cenozoic sedimentary sequence with maximum 10,000 m in thickness, which is located in the Korean Oil Exploration Block VI-1 at the southwestern margin of the Ulleung Basin, is analysed by the expert system, PLAYMAKER2. The Cenozoic sedimentary sequence is divided into two units-lower Miocene and upper Pliocene-Pleistocene sediments. The depositional settings and sedimentary facies of the Miocene sediments interpreted by PLAYMAKER2 in terms of belief values are: for depositional settings, slope; $57.4\%$, shelf; $21.4\%$, basin; $10.1\%$, and for sedimentary facies, submarine fan; $35.7\%$, continental slope; $26.3\%$, delta; $16.1\%$, deep basinplain; $6.1\%$ continental shelf; $3.2\%$, shelf margin; $1.4\%$. The depositional settings and sedimentary facies of the Pliocene-Pleistocene sediments in terms of belief values we: for depositional settings, slope; $59.0\%$, shelf; $22.8\%$, basin; $7.0\%$, and for sedimentary facies, delta; $24.1\%$, continental slope; $22.2\%$, submarine fan; $17.3\%$, continental shelf; $7.0\%$, deep basinplain; $4.8\%$, shelf margin; $2.6\%$. The comparison of the depositional settings and sedimentary facies consulted by PLAYMAKER2 with those of the classical interpretation from previous studies shows resonable similarity for the both sedimentary units-the lower Miocene sediments and the upper Pliocene-Pleistocene sediments. It demonstrates that PLAYMAKER2 is an efficient tool to interpret the depositional setting and sedimentary facies for sediments. However, to be a more reliable system, many sedimentologists should work to refine and add geological rules in the knowledge-base of the expert system, PLAYMAKER2.