HR: 1340h
AN: GP33A-0094    [Abstracts]
TI: A Paleomagnetic Investigation of Upper Carboniferous-Lower Triassic Sedimentary Rocks in the Pyeongchang Area, Korea: Remagnetization and its Tectonic Implications
AU: * Park, Y
EM: aegis@korea.ac.kr
AF: Korea University, Dept. of Earth and Environmental Sciences, Seoul, 136-713 Korea, Republic of
AU: Doh, S
EM: sjdoh@korea.ac.kr
AF: Korea University, Dept. of Earth and Environmental Sciences, Seoul, 136-713 Korea, Republic of
AU: Suk, D
EM: dwsuk@hanyang.ac.kr
AF: Hanyang University, Dept. of Earth and Marine Sciences, Ansan, 425-791 Korea, Republic of
AB: A paleomagnetic investigation has been carried out for the Upper Carboniferous-Lower Triassic Pyeongan Supergroup from the Pyeongchang area, eastern Korea. A total of 350 independently oriented samples were collected from 21 sites for the study. The characteristic remanent magnetization isolated from all the samples was a remagnetized component carried by various magnetic minerals (magnetite, hematite and pyrrhotite). Process of the pervasive remagnetization is regarded as a chemical remanent magnetization based on the synthesis of rock magnetic studies, electron microscope observations and XRD analyses. The paleomagnetic pole position (88.3°E, 83.9°N, A₉₅=4.9°) calculated from the remagnetized component in this study is compared with the Cretaceous and Miocene paleopoles of Korea. This paleomagnetic pole position is far from the previously reported Cretaceous paleopoles in Korea, indicating that the remagnetization occurred after the Late Cretaceous. The paleopole of the remagnetized component is also statistically distinguishable from the Korean Miocene pole at the 5% significance level. The lack of any remarkable geologic events (e.g., orogeny and igneous activity) in the Korean Peninsula may reject the possibility of the post-Miocene remagnetization. Based on the observation of many hydrothermal vein deposits and active igneous activity, which were dated to be the Late Cretaceous to Early Tertiary (94~52 Ma), the timing of the remagnetization can be constrained as the Early Tertiary times (e.g. Paleocene to Eocene). On the other hand, the Cretaceous and Miocene paleomagnetic poles of Korea are plotted along a small circle centered at the reference point (the study area), indicating that the Korean Peninsula was located at similar latitude to the present position, and rotated clockwise about a vertical axis during the Cretaceous Period. However, the paleomagnetic pole position of the remagnetized component is not located on the apparent trajectory from the middle Early Cretaceous pole to the Miocene pole of the Korean Peninsula. The paleolatitude (41°N) calculated from the remagnetized component of the study area is higher than the Cretaceous and Miocene paleolatitudes and the present latitude (37~38°N). Based on the assumption that the remagnetization occurred during the Early Tertiary times, it can raise the possibility that the Korean Peninsula including the study area might experience the latitudinal movement during the Early Tertiary. The Korean apparent polar wander path (APWP) including the paleopoles of remagnetized component is similar to the hairpin-curved APWP of Eurasia at about 50 Ma, which was suggested to reflect the continental collision between India and Asia by several authors. It is interpreted that the India-Asia collisional event might result in the latitudinal movement of the northeastern margin of Eurasia as well as internal deformation of the continent.
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1527 Paleomagnetism applied to geologic processes
DE: 1533 Remagnetization
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005