• The Korean Journal of Petroleum Geology
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• v.1 no.1 s.1
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• pp.63-67
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• 1993

Foraminiferal assemblages from shell beds of Jindo Island indicate shallow water accumulation under warm to temperate condition near the mouth of a small estuary. 11 species of benthonic Foraminifera belonging to 10 genus have been extracted from 12 samples. Cavarotalia annectens dominates, accounting for 57 to 90 percent of the total fauna. The foraminiferal assemblages of the shell beds indicates Post-glacial sedimentation.

• Journal of Marine Life Science
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• v.8 no.1
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• pp.8-31
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• 2023

To understand the distribution and formation mechanism of benthic foraminiferal assemblages, grain size analysis, ¹⁴C radiocarbon dating, and benthic foraminifera analysis were conducted on thirty-two surface sediments collected from the continental shelf of the northern East China Sea, respectively. Surface sediment was composed of sandy mud~muddy sand facies with an average of 52.04% of sand, 13.72% of silt, and 34.20% of clay. These sedimentary facies are palimpsest sediment. Benthic foraminifera was classified into a total of 48 genera and 104 species, including agglutinated foraminifera, calcareous-hyaline, and calcareous-porcelaneous foraminifera. The production rate of agglutinated foraminifera increased toward the Yangtze River area while that of planktonic foraminifera increased toward Jeju Island. Dominant species are Ammonia ketienziensis, Bolivina robusta, Eggella advena, Eilohedra nipponica, Pseudorotalia gamardii, Pseudoparrella naraensis. ¹⁴C radiocarbon datings of Bolivina robusta and Pseudorotalia gamardii with the highest production rate were 2,360±40 yr B.P. and 2,450±40 yr B.P., respectively. In the result of cluster analysis, three assemblages composed of P. gaimardii, B. robusta, and A. ketienziensis-P. naraensis were classified broadly. P. gaimardii assemblage is thought to be formed from about 2.5 yr B.P. at the sea area of the Yangtze River to 50 m in water depth affected by fresh water. B. robusta assemblage is thought to be formed from about 2.4 yr B.P. at the sea area of Jeju Island to 50~100 m affected by offshore water. And then, A. ketienziensisP. naraensis assemblage was formed in the northwest sea area (Central Yellow Sea Mud). These distributions and composition of benthic foraminiferal assemblages formed from about 2.5 yr B.P. in the northern East China Sea are thought to be due to the change of benthic ecology environment that occurred by the sea level increase during the late Holocene.

• Journal of the Korean earth science society
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• v.30 no.4
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• pp.409-426
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• 2009

In the four sedimentary cores from Yeoja Bay, the analyses of grain size, benthic foraminiferal species compositions, assemblages and statistics were carried out to investigate the effects of late Holocene sea-level change on benthic foraminifera. The core sediments were mainly composed of fine-grained silt and clay. The benthic foraminifera were classified into 27 species of 16 genera, 30 species of 21 genera, 50 species of 29 genera and 52 species of 29 genera in Core YC-1 to 4, respectively. In the result of cluster analysis, it seemed that Group 1 (Core YC-1 and 2) of representative A. beccarii assemblages was deposited in upper bay environment and Group 2 (Core YC-3 and 4) of representative E. clavatum-A. beccarii assemblages was deposited in inner bay environment affected by offshore water. In the result of species composition analysis, the production frequency of A. beccarii was gradually decreased from low layer to upper layer, whereas production frequency of E. clavatum and P.F./T.F. was gradually increased to upward. These change patterns appeared in benthic and planktonic foraminifera seemed to reflect the late Holocene sea-level rise in Yeoja Bay.

• The Korean Journal of Quaternary Research
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• v.23 no.2
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• pp.48-55
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• 2009

To investigate the paleoceanographic environmental changes around the Okinawa Trough, Japan, a piston core (RN88-PC5) was conducted on benthic foraminiferal species composition, assemblage, sedimentological and geochemical analyses. Trubidite sediment intercalated in studied core contains different benthic foraminiferal species, dwelling in shallow coral reef species, from normal hemipelagic sediment. These different benthic foraminiferal species and its assemblage are interpreted as reworked sediment when turbidite current occurred, synchronically. Grain size analysis clearly showed that mean grain size difference occurred between trubidite and hemipelagic sediments. Geochemical analysis also showed the difference of chemical composition between two sedimentary facies. Results of the foraminiferal oxygen isotope analysis showing global surface water warming records since the last 10 ka. The geochemcial analysis and previous works showed that turbidite sediment of studied core indicating sporadic occurrence of regional paleoceanographic events. Assemblage of shallow coral reef benthic foraminifera especially occurred with turbidite layer clearly support the sporadic occurrence of paleoceanographic events such as regional earthquake.

• 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.

• Journal of the Korean earth science society
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• v.25 no.8
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• pp.799-811
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• 2004

In this one species of planktonic foraminifers, Neogloboquadrina pachyderma, which has been collected from the sediments cores in the northeast Pacific ODP sites, was computerized through using digitalized images. The foraminiferal communities were analyzed, and the coiling direction of the N. pachyderma was determined by using computer progamming technology. In this way by appling algorithm-based method of reading, the tasks of sorting and analyzing the foraminiferal indiniduals and communities can be performad and high speed on a very large amount of specimens collected. It is found that the study had 90% accordance with the result of stereoscopic observation. This result suggested that digital image analysis could be successfully adopted in the field of micropaleontology.

• 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.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.1 no.1
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• pp.32-45
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• 1996

Analyses of surface sediment textures and recent benthic foraminifera were carried out to understand the change of sedimentary depositional processes in the eastern part of Kwangyang Bay. Echo-sounding images revealed that topographic change of the delta front sheet sand was caused by POSCO (Pohang Steel Company)'s dredging and reclaiming. The sand body prograded toward southeast. Fine sediments are distributed in the northeastern part of the study area. Identification of benthic foraminifera was conducted for the two selected cores from the sand body for the first time. Dominant species are Ammonia beccarii, Elphidium excavatum and Quinqueloculina lamarckiana. No abrupt change of benthic foraminiferal assemblage was observed from the sedimentary sequences.

• 한국해양학회지
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• v.22 no.3
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• pp.153-167
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• 1987

The most usually adopted methods from the collection of samples laboratory procedures, to basic analysis of assemblages for the quantitative study of benthic foraminifera are reviewed. Standard methods of treatment of sampleswith emphasis on the effective detection of contamination through routine dip of sieved into Methylene Blue solution after every washing of samples are proposed to minimize differences due to individuals and for comparisons of results in future. Some basic characteristics for the quantitative analyses are also reviewed with appropriate examples. These characteristics are related to toraminiferal abundance, wall structures, condition of test conservation, diversity and related characteristics, faunal similarith between samples, and occurrence of planktonic foraminifera.

• Journal of the Korean earth science society
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• v.27 no.4
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• pp.464-474
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• 2006

The paleoceanography since 14 ka was reconstructed based on the planktic foraminiferal assemblages of core sediments from the outer shelf of the Korea Strait. Planktic foraminifera in the core sediments can be divided into four assemblages: A, B, C, and D. Assemblage A consists mainly of Globigerinoides ruber group and Globigerinoides conglobatus with low abundance (less than 10%), indicating the tropical-subtropical water mass. Assemblage B is composed of Pulleniatina obliquiloculata and Neogloboquadrina dutertrei, the indicator of Kuroshio Current, and shows the aspect of the inflow of the Tsushima Current into the Korea Strait. Assemblage C yields polar-subpolar species, mainly Neogloboquadrina incompta and N. pachyderma. It decreases upward of the core. Assemblage D contains coastal water species such as Globigerina bulloides and G. quinqueloba. It is abundant in the lower to middle region of the core. From the analysis of distributions of each assemblage and the result of age datings in the core, it is suggested that the Korea Strait played a role of channelling the East China Sea and the East Sea after the LGM (ca. 14 ka). During this time, the coastal water, affected by fresh waters originated from the river systems of China and/ or the Korean Peninsula, flourished around the Korea Strait and theses coastal water might entered to the East Sea. Around 8.5 ka, the effect of the Tsushima Current started to strengthen in this region, and the present current system seems to be formed at about $7{\sim}6ka$.