Micropaleontological and seismic observations for early developmental stage of the southwestern Ulleung Basin, East Sea (Japan Sea)

• Published in: The island arc Vol. 16; no. 2; pp. 262 - 275
• Main Authors: Yun, Hyesu, Yi, Songsuk, Oh, Jinyong, Byun, Hyunsook, Shin, Kooksun
• Format: Journal Article
• Language: English
• Published: Melbourne, Australia Blackwell Publishing Asia 01-06-2007
• Subjects: biostratigraphy; paleoenvironment; Pohang Basin; syn-rift; Ulleung Basin; INW, Japan Sea; INW, Japan Sea, Ulleung Basin; INW, Korea, Rep., Pohang Basin
• ISSN: 1038-4871; 1440-1738
• DOI: 10.1111/j.1440-1738.2007.00571.x

The Ulleung Basin is located in the southwestern part of the East Sea (Japan Sea) and contains thick Neogene sediment. Detailed examination of the stratigraphic distribution of dinoflagellates was carried out on samples from the onshore Pohang Basin (E well) and two wells (Gorae I and Dolgorae VII) in the southwestern Ulleung Basin, to investigate the early evolution of the basin. The results show that thick syn‐rift sediments mainly consist of terrestrial deposits and are widespread over the basin. This supports an extensional tectonic origin for the basin. The initiation of the deposits dates back to 17–16.4 Ma. Furthermore, well‐preserved Eocene to Oligocene dinoflagellate taxa found in Miocene deposits of wells implies that the age of initial rifting might be Oligocene or earlier. Our results provide constraints for understanding the opening process of the East Sea.