New and revised set of Cretaceous paleomagnetic poles from Hong Kong: implications for the development of southeast China

A paleomagnetic study of Upper Cretaceous (∼80 Ma) dikes from Hong Kong was conducted with the aim of better understanding the Late Cretaceous-Cenozoic kinematic history of southeast China. Twelve out of seventeen sites collected from four dikes revealed primary TRMs and yield a Late Cretaceous paleopole at 69.3°N/211.2°E, where A95=8.9° and K=107. A synthesis of South China Block Cretaceous poles indicates that Coastal Southeast China, which is bounded by the Lianhuashan Fault Zone to the northwest and the Changle-Nanao Fault Zone to the southeast, has moved relative to inland Central South China. The discordant Cretaceous paleopoles from the South China Block suggest a moderate net clockwise rotation of the Coastal Southeast China relative to Central South China since the Late Cretaceous. This clockwise rotation is probably the result of micro-blocks along the South China margin experiencing vertical-axis rotations in response to the penetrative dextral shear along the SE China margin during oblique subduction of the Pacific Plate beneath South China. An alternative interpretation involves regional extension that displaced a raft-block southeastwards of the margin, generating apparent paleomagnetic records with no real block rotations.