Radiolarians from the Pohang Basin, Southeast Korea and Paleoceanographic Implications

• Published in: Acta geologica Sinica (Beijing) Vol. 86; no. 6; pp. 1426 - 1433
• Main Authors: BAK, Young-Suk, LEE, Jong-Deock, YUN, Hyesu, OH, Jinyong, LEE, Seong-Joo
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.12.2012; Wiley Subscription Services, Inc; Kyungpook National University, Daegu, Korea%Chonbuk National University, Jeonju, Korea%Chungnam National University, Daejon, Korea
• Edition: English ed.
• Subjects: Alliances; depositional environment; Pohang Basin; Radiolaria; radiolarian; upwelling; 东南亚; 古海洋学; 微体古生物化石; 放射虫; 朝鲜半岛; 生物地层学; 盆地; 韩国; Korea, Rep; INW, Korea, Rep; INW, Korea, Rep., Pohang Basin; INW, Pacific, Korea Strait; radiolarian; depositional environment; upwelling; Pohang Basin
• ISSN: 1000-9515; 1755-6724
• DOI: 10.1111/1755-6724.12011

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.