• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.205-216
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• 2011

Mineral compositions of 69 southeastern Yellow Sea surface sediments collected at the Korea Ocean Research and Development Institute (KORDI) cruise in 2010, were determined using the quantitative X-ray diffraction analysis. Southeastern Yellow Sea surface sediments are composed of major minerals (quartz 49.1%, plagioclase 13.0% and alkali feldspar 9.3%), clay minerals, calcite, and aragonite. Illite (9.4%) is the most abundant clay mineral, chlorite (4.6%) is the second, and kaolinite (0.8%) is few. Quartz and alkali feldspar contents are high in coarse-grained sediments, whereas amphibole and clay mineral contents are high in fine-grained sediments. Quartz, plagioclase, alkali feldspar, chlorite, and kaolinite contents are higher, and illite content is lower in mud zone 1 corresponding to south margin of Central Yellow Sea Mud than in mud zone 2, a part of Southeastern Yellow Sea Mud. Difference of mineral composition between two mud zone suggests that source of fine sediment may be different in two mud zone and Southeastern Yellow Sea Mud might be largely supplied from the Keum and Youngsan rivers in southern part of the west coast in the Korean Peninsula.

• 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.