Stratigraphic Response to
Tectonic Evolution of the Cretaceous Gyeongsang Basin, Korea: An Example of
Tectonically Controlled Lake Basin in Active
Margin Setting
Ryu, In-Chang1, Seon-Gyu Choi2, Soo-Meen
Wee3, Tae-Hoon Kim4, Chang-Yoon
Lee5 (1) Kyungpook National University, Daegu, South Korea (2) Korea University, Seoul, South Korea
(3) Korea National University of Education, Cheongju,
(4) Kyungpook National University, Department of
Geology, Daegu, South Korea (5) Kyungpook
National University, Department of Geology, Daegu,
Korea, South Korea
The Cretaceous Gyeongsang Basin, onshore southeastern Korea, comprises more than
9,000 m of siliciclastic and volcanic strata that
were deposited in a lake basin in active continental margin setting. Detailed stratigraphic, sedimentologic,
and paleontologic data are integrated to make a
coherent stratigraphic framework in the basin. A
newly proposed integrated stratigraphic framework
indicates that strata in the basin can be subdivided into five distinct stratigraphic units that represent pre-rifting, syn-rifting, inversion I, II, and III stages. The Gyeongsang Basin was formed as a lake
basin during the Early Cretaceous. In the Late Cretaceous, however, the basin
was deformed by three-staged sequential deformation of north-south,
northwest-southeast, and east-west compressions. The formation and deformation
of the basin has been largely controlled by the change of motion of the Izanagi Plate from north to northwest during the
Cretaceous. In the early Cretaceous, the Izanagi
Plate began to subduct northward beneath the Eurasian
Plate and caused the left-lateral strike-slip fault systems in the southeastern
part of the Korean Peninsula. The left-lateral
wrenching of these fault systems was causally linked to development of lake
basins in the southeastern part of the peninsula. However, northwestward
movement of the Izanagi Plate during the Late
Cretaceous probably led to the extensive volcanism and sequential deformations
in the basin. Together with the spatial and temporal correlation of the
Cretaceous basins in adjacent areas, this stratigraphic
and tectonic model of the Gyeongsang Basin provides a new geologic
paradigm to delineate the sophisticated tectonic history of East Asia during the Cretaceous.