LA-MC-ICP-MS zircon U-Pb dating was conducted to constrain the timing of fossil formation and the depositional age of the uppermost Jinju Formation located in Natural Monument No. 534 (Tracksite of Pterosaurs, Birds, and Dinosaurs in Hotandong, Jinju), and 87 Cretaceous, 1 Precambrian, and 2 Jurassic zircons were obtained from 90 valid analytical points. Most Cretaceous zircons were found to have a youngest graphical peak age of ca. 106.5 Ma, suggesting the depositional age of the uppermost Jinju Formation. Based on this study and previous works, the average sedimentation rate of the Jinju Formation was calculated to be approximately 0.17-0.31 mm/year in the Milyang Subbasin, and the Cretaceous zircons of the uppermost Jinju Formation seem to have originated mainly from the western or northwestern parts of the Gyeonggi Massif. Unlike the Nakdong and Hasandong formations of the Sindong Group, most zircons analyzed in the uppermost Jinju Formation were Cretaceous. This suggests that volcanic activity occurred in the area closer to the Gyeongsang Basin due to the roll-back of subducting paleo-Pacific Plates during the Jinju period.

Abstract
Introduction
Study Area and General Geology
Samples and Analytical Method
Results
Discussion
    Depositional age of the Natural Monument No. 534 tracksite and average sedimentation rate of the Jinju Formation
    Provenance of the Cretaceous zircons in the study area
    Increase of the Cretaceous zircons over time in the Sindong Group
Conclusion
References

• Yong-Un Chae(Department of Geological Sciences, Pusan National University)
• Jong Deock Lim(National Research Institute of Cultural Heritage)
• Cheong-Bin Kim(Department of Physics Education, Sunchon National University)
• Kyung Soo Kim(Department of Science Education, Chinju National University of Education)
• Sujin Ha(Department of Geological Sciences, Pusan National University)
• Hyoun Soo Lim(Department of Geological Sciences, Pusan National University) Corresponding author