Mesozoic tectonic evolution of eastern China: Insights from the Changshan Islands, NE China.

The Changshan islands are scattered among the Yellow Sea east of the Liaodong Peninsula, west of North Korea and north of the Sulu Orogenic Belt. They consist of three lithotectonic units: i) Archean gneiss, ii) Paleoproterozoic marble and micaschists, and iii) Neoproterozoic weakly metamorphic sedimentary rocks. Three stages of deformation (D 1 -D 3) documented in this study indicate that Changshan islands are a key region to decipher the Mesozoic tectonic evolution of eastern China. The earliest deformation D 1 corresponds to a ductile deformation with NE-SW trending mineral and stretching lineations and top-to-the-NE sense of shear. The deformation D 2 , observed in the micaschists and sedimentary rocks, is characterized by the SW-verging folds with NE-dipping axial planar cleavage S 2 and SW-directed thrusting. D 2 could be considered as the back-folding and back-thrusting of the D 1. D 3 is expressed by the NE-SW trending low-angle brittle and ductile detachment faults representing a NW-SE extensional event. To the east of Guanglu and Guapi islands, two samples from a granite pluton that only record D 3 fabrics yield SIMS zircon ages of 165.4 ± 1.6 Ma and 164.7 ± 1.5 Ma, which indicate that D 1 and D 2 occurred earlier than 165 Ma, while D 3 is younger than this age. Similar geometric and kinematic features with those of the South Liaodong Peninsula suggest that D 1 and D 2 occurred in the Middle-Late Triassic as the structural response of overriding plate to the continental subduction of the South China Block (SCB) beneath the North China Craton (NCC), while the D 3 occurred in the Early Cretaceous during the development of the Liaonan Metamorphic Core Complex (MCC). The ductile shear zone and brittle normal faults of the Changshan islands represent the early extensional structures of the Liaonan MCC. They may develop further southeastward and controlled the early development of the North Yellow Sea Basin. • The Changshan islands experienced three stages of deformation in the Mesozoic. • The D 1 and D 2 responded to the Middle-Late Triassic continental subduction of the SCB beneath the NCC. • The structures of D 3 resulted from the Early Cretaceous NW-SE extension throughout the whole eastern Eurasian continent. [ABSTRACT FROM AUTHOR]