A total of 16 specimens of fossil-winged fruits were found from the Middle Miocene marine deposits, Duho Formation, Pohang Basin, Korea. They were identified into two structurally different groups： 15 specimens into ...A total of 16 specimens of fossil-winged fruits were found from the Middle Miocene marine deposits, Duho Formation, Pohang Basin, Korea. They were identified into two structurally different groups： 15 specimens into a winged fruit of Fraxinus, and one specimen of Liriodendron. The most samaras （13 specimens） were identified as Fraxinus oishii, which is characterized by narrowly ovate or ovate-elliptic shapes that are 2.7-3.6 cm in length and 0.7-1 cm in width （i/w ratio=3.4-4）. The apexes of the Fraxinus oishii samara are round or slightly emarginated, and a seed of the samara is always located at the base, of which the general shape is narrow rhombic-ellipsoidal. The seed is 1.2-2 cm long and 0.5-0.7 cm wide. Two specimens are different from the samara of Fraxinus oishii. They have a 6.6 length/width ratio （3.3 cm long and 0.5 cm wide）, and thus, are temporarily classified into the Fraxinus sp. One specimen was recognized as a winged seed of Liriodendron meisenense. The wing is broadly lanceolate to elliptic in shape, has a smooth, acute apex, and is approximately 3 cm long and 0.7 cm wide. Samaras of Fraxinus oishii and Liriodendron meisenense were early reported from the Middle Miocene deposits from North Korea, but these specimens are the first discovery in South Korea. Further study of the Duho Formation may connect flora relationships between North and South Korea.展开更多
A great number of the Cenozoic echinoid fossils were found from the Duho Formation of the Pohang Basin,Korea.Most of the echinoid fossils,ranging from 2-8 cm in diameter,were preserved as flattened or crushed specimen...A great number of the Cenozoic echinoid fossils were found from the Duho Formation of the Pohang Basin,Korea.Most of the echinoid fossils,ranging from 2-8 cm in diameter,were preserved as flattened or crushed specimens.However,each side(oral or aboral) containing diagnostic features is well preserved in the flattened specimens.Korean echinoid fossils belonging to the order Spatangoida,a group展开更多
About 40 specimens of fossil ophiuroids were collected from two formations of the Cenozoic marine deposits,Duho Formation and Hagjeon Formation, Pohang Basin,Korea.A few specimens were three-dimensionally preserved:mo...About 40 specimens of fossil ophiuroids were collected from two formations of the Cenozoic marine deposits,Duho Formation and Hagjeon Formation, Pohang Basin,Korea.A few specimens were three-dimensionally preserved:most of them were remained flattened and articulated.Although a gross morphology is well preserved in some specimens,the details such as disk shape and plates which are the most important diagnostic features were not observed.展开更多
A great number of fossil scallops were found from the Duho Formation of the Pohang Basin,Korea.Most of the specimens are preserved as slightly altered original carbonate shells,and internal and external molds were als...A great number of fossil scallops were found from the Duho Formation of the Pohang Basin,Korea.Most of the specimens are preserved as slightly altered original carbonate shells,and internal and external molds were also observed in the specimens whose calcareous materials were washed out.In particular, external and internal molds are more frequently observed from the thin and small(less than 1 cm展开更多
The Middle Miocene Duho Formation of the Yeonil Group,Pohang Basin,Korea is one of the best recognized formations for the Cenozoic plant fossils, including various leaves,reproductive organs,and fossil woods.We,in thi...The Middle Miocene Duho Formation of the Yeonil Group,Pohang Basin,Korea is one of the best recognized formations for the Cenozoic plant fossils, including various leaves,reproductive organs,and fossil woods.We,in this paper,first report winged fruits(10 specimens) from the Duho Formation.They were identified into two structurally different groups:展开更多
We identified a total of 101 species and two subspecies of radiolarians belonging to 56 genera from 95 samples collected from the Hagjeon and Duho Formations in the Pohang Basin of the southeastern Korean Peninsula. O...We identified a total of 101 species and two subspecies of radiolarians belonging to 56 genera from 95 samples collected from the Hagjeon and Duho Formations in the Pohang Basin of the southeastern Korean Peninsula. On the basis of the biostratigraphic range of Cyrtocapsella cornuta and Theocorys redondoensis, the depositional period of the upper Hagjeon and lowest Duho Formations was determined to be early to late Middle Miocene. The occurrence of deep-dwelling radiolarians indicates that the paleobathymetry seems to become gradually progressing toward an upper bathyal environment in the middle part of the Hagjeon Formation. However, we prefer to accept another interpretation for the occurrence of deep-sea indicators in the Hagjeon and the lowest part of the Duho Formations, and consider the presence of a region of upwelling cold water that might have simulated a deep-water environment in relatively shallow water. This interpretation is based on the present upwelling of a cold-water mass off the southeast coast of Korea, the occurrence of upwelling microfossils from the Pohang Basin, and the effect of the closing of the Korea Strait approximately 15 Ma. We also considered that the uppermost part of the studied section represents a shallow-water environment.展开更多
A total of 85 samples, collected from the UBGH1-9 core taken from the Ulleung Basin, East Sea, Korea, were analyzed using diatom assemblages. 111 diatom species belonging to 46 genera were identified, and three diatom...A total of 85 samples, collected from the UBGH1-9 core taken from the Ulleung Basin, East Sea, Korea, were analyzed using diatom assemblages. 111 diatom species belonging to 46 genera were identified, and three diatom assemblage zones were established on the basis of occurrence and distribution pattern of diatoms. Diatom assemblage zone I（134.10–174 m） is characterized by a relatively high abundance of marine species, while the increased number of the brackish species is recorded in diatom assemblage zone II（75–125 m）. The assemblage zones IIIa became drastic drop of valve abundances and brackish planktons, whereas it became increase during the IIIb. High Td values which indicate an influence of warm current are recorded both in diatom assemblage zone I and III, and low Td values in diatom assemblage zone II. Analysis of diatom assemblages indicating that the depositional condition moved from oceanic to littoral-neritic environments and that paleotemperature underwent a shift from warm to cold condition at the middle interval, and from cold to warm condition in the upper interval of the UBGH1-9 core. This suggests that the lower（130–162 m） and upper intervals（0–20 m） of the UBGH1-9 core were deposited in the warm current condition（Tsushima Warm Current）.展开更多
基金supported by BK21 project of Department of Geology,Kyungpook National University, KNU
文摘A total of 16 specimens of fossil-winged fruits were found from the Middle Miocene marine deposits, Duho Formation, Pohang Basin, Korea. They were identified into two structurally different groups： 15 specimens into a winged fruit of Fraxinus, and one specimen of Liriodendron. The most samaras （13 specimens） were identified as Fraxinus oishii, which is characterized by narrowly ovate or ovate-elliptic shapes that are 2.7-3.6 cm in length and 0.7-1 cm in width （i/w ratio=3.4-4）. The apexes of the Fraxinus oishii samara are round or slightly emarginated, and a seed of the samara is always located at the base, of which the general shape is narrow rhombic-ellipsoidal. The seed is 1.2-2 cm long and 0.5-0.7 cm wide. Two specimens are different from the samara of Fraxinus oishii. They have a 6.6 length/width ratio （3.3 cm long and 0.5 cm wide）, and thus, are temporarily classified into the Fraxinus sp. One specimen was recognized as a winged seed of Liriodendron meisenense. The wing is broadly lanceolate to elliptic in shape, has a smooth, acute apex, and is approximately 3 cm long and 0.7 cm wide. Samaras of Fraxinus oishii and Liriodendron meisenense were early reported from the Middle Miocene deposits from North Korea, but these specimens are the first discovery in South Korea. Further study of the Duho Formation may connect flora relationships between North and South Korea.
文摘A great number of the Cenozoic echinoid fossils were found from the Duho Formation of the Pohang Basin,Korea.Most of the echinoid fossils,ranging from 2-8 cm in diameter,were preserved as flattened or crushed specimens.However,each side(oral or aboral) containing diagnostic features is well preserved in the flattened specimens.Korean echinoid fossils belonging to the order Spatangoida,a group
文摘About 40 specimens of fossil ophiuroids were collected from two formations of the Cenozoic marine deposits,Duho Formation and Hagjeon Formation, Pohang Basin,Korea.A few specimens were three-dimensionally preserved:most of them were remained flattened and articulated.Although a gross morphology is well preserved in some specimens,the details such as disk shape and plates which are the most important diagnostic features were not observed.
文摘A great number of fossil scallops were found from the Duho Formation of the Pohang Basin,Korea.Most of the specimens are preserved as slightly altered original carbonate shells,and internal and external molds were also observed in the specimens whose calcareous materials were washed out.In particular, external and internal molds are more frequently observed from the thin and small(less than 1 cm
文摘The Middle Miocene Duho Formation of the Yeonil Group,Pohang Basin,Korea is one of the best recognized formations for the Cenozoic plant fossils, including various leaves,reproductive organs,and fossil woods.We,in this paper,first report winged fruits(10 specimens) from the Duho Formation.They were identified into two structurally different groups:
基金supported by Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Education,Scienceand Technology (2011-0002705)
文摘We identified a total of 101 species and two subspecies of radiolarians belonging to 56 genera from 95 samples collected from the Hagjeon and Duho Formations in the Pohang Basin of the southeastern Korean Peninsula. On the basis of the biostratigraphic range of Cyrtocapsella cornuta and Theocorys redondoensis, the depositional period of the upper Hagjeon and lowest Duho Formations was determined to be early to late Middle Miocene. The occurrence of deep-dwelling radiolarians indicates that the paleobathymetry seems to become gradually progressing toward an upper bathyal environment in the middle part of the Hagjeon Formation. However, we prefer to accept another interpretation for the occurrence of deep-sea indicators in the Hagjeon and the lowest part of the Duho Formations, and consider the presence of a region of upwelling cold water that might have simulated a deep-water environment in relatively shallow water. This interpretation is based on the present upwelling of a cold-water mass off the southeast coast of Korea, the occurrence of upwelling microfossils from the Pohang Basin, and the effect of the closing of the Korea Strait approximately 15 Ma. We also considered that the uppermost part of the studied section represents a shallow-water environment.
基金supported by the "Geological and Geochemical Studies on Gas Hydrate" project of the KIGAM funded by the MKE, KGHDO, KNOC, and KOGASthe Basic Science Research Program through the National Research Foundation of Korea (NRF -2012R1A1A2003814)
文摘A total of 85 samples, collected from the UBGH1-9 core taken from the Ulleung Basin, East Sea, Korea, were analyzed using diatom assemblages. 111 diatom species belonging to 46 genera were identified, and three diatom assemblage zones were established on the basis of occurrence and distribution pattern of diatoms. Diatom assemblage zone I（134.10–174 m） is characterized by a relatively high abundance of marine species, while the increased number of the brackish species is recorded in diatom assemblage zone II（75–125 m）. The assemblage zones IIIa became drastic drop of valve abundances and brackish planktons, whereas it became increase during the IIIb. High Td values which indicate an influence of warm current are recorded both in diatom assemblage zone I and III, and low Td values in diatom assemblage zone II. Analysis of diatom assemblages indicating that the depositional condition moved from oceanic to littoral-neritic environments and that paleotemperature underwent a shift from warm to cold condition at the middle interval, and from cold to warm condition in the upper interval of the UBGH1-9 core. This suggests that the lower（130–162 m） and upper intervals（0–20 m） of the UBGH1-9 core were deposited in the warm current condition（Tsushima Warm Current）.
