During subduction, continental margins experience shortening along with inversion of extensional sedimentary basins. Here we explore a tectonic scenario for the inversion of two-phase extensional basin systems, where the Early−Middle Jurassic intra-arc volcano-sedimentary Oseosan Volcanic Complex was developed on top of the Late Triassic−Early Jurassic post-collisional sequences, namely the Chungnam Basin. The basin shortening was accommodated mostly by contractional faults and related folds. In the basement, regional high-angle reverse faults as well as low-angle thrusts accommodate the overall shortening, and are compatible with those preserved in the cover. This suggests that their spatial and temporal development is strongly dependent on the initial basin geometry and inherited structures. Changes in transport direction observed along the basement-sedimentary cover interface is a characteristic structural feature, reflecting sequential kinematic evolution during basin inversion. Propagation of basement faults also enhanced shortening of the overlying sedimentary cover sequences. We constrain timing of the Late Jurassic−Early Cretaceous (ca. 158−110 Ma) inversion from altered K-feldspar 40Ar/39Ar ages in stacked thrust sheets and K-Ar illite ages of fault gouges, along with previously reported geochronological data from the area. This “non-magmatic phase” of the Daebo Orogeny is contemporaneous with the timing of magmatic quiescence across the Korean Peninsula. We propose the role of flat/low-angle subduction of the Paleo-Pacific Plate for the development of the “Laramide-style” basement-involved orogenic event along East Asian continental margin.
Bibliographical noteFunding Information:
This research was also supported by Basic Science Research Program through National Research Foundation of Korea funded by the Ministry of Education, Science and Technology ( 2018R1C 1B6003851 ) to S.-I. Park and 2015R1D1A1A09058914 to S. Kwon. This research was also supported by the 2017R1A6A1A07015374 (Multidisciplinary study for assessment of large earthquake potentials in the Korean Peninsula) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT , Korea to S.K. This work represents part of S.-I. Park's Ph.D. Research performed at Yonsei University.
All Science Journal Classification (ASJC) codes
- Earth and Planetary Sciences(all)