Structural inversion refers to the reverse reactivation of extensional faults that influence basin shortening accommodated by contractional faults or folds. On the Korean peninsula, Miocene inversion structures have been found, but the Cretaceous rocks on Geoje Island may have undergone inversion as early as the Upper Cretaceous. To evaluate the structural inversion on Geoje Island, located on the eastern side of South Korea, and to determine the effects of preexisting weakness zones, field-based geometric and kinematic analyses of faults were performed. The lithology of Geoje Island is dominated by hornfelsified shale, siltstone, and sandstone in the Upper-Cretaceous Seongpori formation. NE and NW-oblique normal faults, conjugate strike-slip (NW-sinistral transpressional and E-W-dextral transtensional) faults, and NE-dextral transpressional faults are the most prominent structural features in Geoje Island. Structural inversion on Geoje Island was evidenced by the sinistral and dextral transpressional reactivation of the NW and NE-trending oblique normal faults respectively, under WNW-ESE/NW-SE compression, which was the orientation of the compressive stress during the Late Cretaceous to Early Cenozoic.

1. Introduction
2. Geological Settings of the Area
3. Research Methods
4. Results
    4.1. Site 1. Sinseondae site
    4.2. Site 2. Gucheon-ri site
    4.3. Site 3. Yulpo-ri site
    4.4. Site 4. Dapo-ri site
5. Discussion
    5.1. Structural Inversion
Conclusion
Acknowledgment

• Francois Hategekimana(Gelogical Structures and Geohazard Research Lab, Major of Environmental Geosciences, Pukyong National University, Busan 48513, Korea, Department of Geology, College of Science and Technology, University of Rwanda, Kigali 3900, Rwanda)
• Mohammed S. M. Adam(Gelogical Structures and Geohazard Research Lab, Major of Environmental Geosciences, Pukyong National University, Busan 48513, Korea)
• Young-Seog Kim(Gelogical Structures and Geohazard Research Lab, Major of Environmental Geosciences, Pukyong National University, Busan 48513, Korea) Corresponding author