• 한국해양학회지
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• v.27 no.2
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• pp.123-136
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• 1992

As a result of faunal analysis on 50 bottom samples bearing a total of 183 species of the Recent benthonic foraminifers from the West and South Sea of korea, five bioassociations (groups of species) and five biotopes (groups of samples) were discriminated. From the areal distribution of biotopes in combination with bioassociations and the available ecological data of foraminiferal species, five biofacies are recognized: (1) Southern Inner Shelf Biofacies; (2) Southern Coast Biofacies; (3) Northern Middle Shelf Biofacies; (4) Central Middle Shelf Biofacies; and (5) Southern Outer Shelf and Upper Slope Biofacies. The biofacies are defined by a group of sampling stations containing a diagnostic species association and can be related to the major current pasterns and water masses in the West and South Sea of Korea: Southern Inner Shelf Biofacies is related to the Coastal Waters and drainage from China; Southern Coast Biofacies is related to the Coastal Waters and drainage from Korea; Northern Middle Shelf Biofacies is related to the Coastal Waters and Yellow Sea Cold Water, Central Middle Shelf Biofacies is related to the Yellow Sea Warm Current; and Southern Outer Shelf and Upper Slope Biofacies is related to the Tsushima Warm Current.

• Journal of Wetlands Research
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• v.8 no.3
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• pp.51-65
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• 2006

Surface sediments for sedimentary analyses were sampled at 199 stations in the study area in August 2003. The surface sediments consisted of six sedimentary facies. Generally, sandy mud sediments dominated in the southern tidal flat of Ganghwa Island and sand sediments dominated in channel and subtidal zones of the western part of Ganghwa Island. The area of sandy mud sediment extended to eastward tidal flat compared to sedimentary facies in August 1997. In 30 surface sediment samples from the Ganghwa tidal flat and subtidal zone, 61 species were recorded in total assemblages, including 34 species of living population. Ammonia beccarii and Elphidium etigoense in living population and Ammonia beccarii, Elphidium etigoense, Jadammina sp. and Textularia earlandi in total assemblage were widely distributed. Generally, relatively large numbers of species and high values of species diversity occurred in the area of western part of tidal flat. Cluster analysis of total assemblages discriminates four biofacies. Biofacies 1 indicated eastern part of the tidal flat and biofacies 4 indicated western part of the tidal flat. Biofacies 3 were transitional zone between biofacies 1 and 4.

• 한국해양학회지
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• v.30 no.5
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• pp.493-511
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• 1995

Analysis of the Late Quaternary benthic foraminifera in the cores from the western part of the East Sea, Korea, indicates several distinct changes in the paleoenvironments during the deposition. The palecology of biofacies of Cores PC-1 from the upper slop and PC-2 from the rise shows several distinct changes in bottom water temperatures during the late Quaternary. The Core PC-4 from the Ulleung Basin generally consists of agglutinated genus, Muiliammina, and anaerobic calcareous genus, Bolivina, in biofacies, suggesting that the anoxic bottom condition was prevailed during the deposition. Benthic foraminiferal rare or barren zones in the Cores indicate the limits of water circulation caused by lower sea-level in the regions during the glacial period through the Late Quaternary. The changes of benthic foraminiferal biofacies reflect temporal and spacial variations in overall bottom environments, such as bottom water temperature, dissolved oxygen, and water circulation pattern. The benthic foraminiferal data can be used to interpret paleoclimatic conditions and predict global sea-level changes, and the results of these studies should be useful to understand the evolutional history of the East Sea through the Late Quaternary.

• Journal of the korean society of oceanography
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• v.35 no.2
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• pp.109-123
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• 2000

Depositional processes of fine-grained sediments were investigated on the basis of sediment transport vector analysis and identification of benthic foraminiferal assemblages in Yoja Bay, southern coast of Korea. The bay is a semi-enclosed embayment where extensive mud flats occur with a width up to about 4 km. Most surface sediments are poorly sorted (sorting values: 1.9-3.0 ${\phi}$) mud and silt (mean grain size: 6.0-8.7 ${\phi}$), except for the tidal inlets with basement rocks locally exposed. Grain-size distribution shows a fining tendency toward the basin center near the Yoja Island, implying a possible existence of turbidity maximum and relatively rapid settling of fine-grained sediments. The agglutinated foraminiferal taxa are dominant in the inner bay and decrease in abundance toward the mouth of the bay. Species diversities are higher in the outer bay, due to mixing of the offshore faunas with those of the bay. Four groups of benthic foraminiferal assemblages, identified by cluster analysis, represent the bay. Biofacies I and ll with relatively lower diversities are dominated by Ammobaculites exiguus and Ammonia beccarii, suggestive of influx of fresh water. In contrast, biofacies III and IV with relatively higher diversities include increased amounts of calcareous genus Elphidium and Quinquelocuzina, accounting for strong influence of sea water from the offshore. The fluvial discharge in summer floods appears to develop a bay-wide, clockwise lateral circulation in Yoja Bay, a typical of well-mixed estuaries. Accordingly, the foraminiferal assemblages of the surface sediments well show a sign of this circulation. The dominant inflow of the offshore water into the western part of the bay has resulted in more extensive muddy tidal flats compared to the eastern narrower counterpart.

• 한국해양학회지
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• v.30 no.3
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• pp.184-196
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• 1995

The line-SW is located in the mouth of Gomso Bay (20 Km long and 5-8 Km wide),west coast of Korea. This area is composed of sand flat, mud flat, sand shoal and chenier, The difference of physical, geological and geomorphic conditions in subenvironments of the bay may control and produce distingtive foraminiferal populations and assemblages. This study investigates whether five a priori subenvironments (five local zonations) in Gomso-Bay tidal flat can be distinguished from each other on the basis of total (living plus dead) foraminiferal assemblages. Seventy-four species (67 benthic; 7 planktonic) were recorded in total assemblages of surface sediments from 10 stations. Ammonia beccarii tepida, Discorbis candeiana, Elphidium etigoense and Eponides nipponicus were most dominant species in living and total assemblages. The relative abundance (%) of living population was high at upper flat and decreased from upper to lower flat. The low percentages of living populations in middle to lower flat are probably influenced by the decreasing reproduction of foraminifera caused by high energy condition and addition of dead species from offshore. The occurence of planktonic foraminifera in middle to lower flat (5.3∼6.6%) indicates introduction of planktonic foraminifera from offshore by storm and/or tidal current. The relatively high numbers of species in lower middle to lower flat are probably caused by a mixing of faunas from these areas and offshore. The high numbers of total individuals per 50 ml of sediment in upper flat indicate that this area is a relatively stable environment where waves and currents are protected by the chenier. Five biofacies of the total foraminiferal assemblages were established on the basis of dominant species (those representing more than 20% of the total assemblages in any station) in the five a priori subenvironments recognized along the Line-SW transect in Gomso-Bay tidal flat. Five biofacies are potentially useful in paleoenvironmental interpretation in late Quaternary Gomso-Bay tidal deposits.

• Journal of the Korean earth science society
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• v.21 no.4
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• pp.423-436
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• 2000

The lithofacies, biofacies, and paleosol development of the Jindong Formation, the Geoncheonri Formation, and the lacustrine deposits of Mt. Hwangryeong at Pusan, which occur in the southeastern part of the Gyeongsang Basin, were analyzed in comparative sedimentology and in stratigraphy. The common features of these lacustrine deposits are: 1) clastic deposits are prevailing, 2) deltaic deposits are not associated, 3) mudflat deposits are common, and 4) stromatolites are absent. The distinct differences among these deposits are: 1) in the Jindong Formation, the mudflat deposits are predominant, pedogenic calcretes are commonly present, and dinosaur tracks frequently occur, compared with other two lacustrine deposits, and 2) in the Geoncheonri Formation, invertebrate fossils are relatively common and storm deposits are not recognized, compared with other deposits, and 3) evaporite mineral casts and tuffaceous turbidite deposits are common in the Mt. Hwangryeong lacustrine deposits. In stratigraphy, the Geoncheonri Formation is correlated with the lower part of the Jindong Formation, and the Mt. Hwangryeong lacutsrine deposits are deemed to overlie the Jindong Formation. On the basis of comparative sedimentology and stratigraphic relationship among these lacustrine deposits, general paleoenvironements of the southeastern part of the Gyeongsang Basin from the late Hayang time to the early Yucheon time are interpreted as follows. During the late Hayang time, tectonic and volcanic activities were generally inacitive in the Gyeongsang Basin, and lacustrine environments expanded since the paleoclimatic condition became less arid compared with the middle Hayang time. In general, however, paleoclimate during the late Hayang time was still arid, and wetting and drying periods were alternated. The occasional occurrences of severe droughts were also characteristic of the late Hayang time. Mudflats existed in wide area in the southeastern part of the Gyeongsang Basin during the late Hayang time, and sedimentation rate was accordingly low. The sedimentation rate became relatively high during the latest Hayang time and the early Yucheon time since tectonic and volcanic activities had been active. Generally arid climate continued for the early Yucheon time, enough for evaporite minerals to precipate occasionally.