Middle Triassic paleomagnetic results from central Hubei province, China and their tectonic implications

Twenty one sites consisting of 4 to 7 samples per site were drilled from the redbeds of the Middle Triassic Badong Formation from central Hubei province, China. These samples were subjected to progressive thermal demagnetization which revealed two components of magnetization. The low temperature (A) component was probably acquired at a late stage of folding and is similar in direction to the late Mesozoic overprint widely observed in the eastern Yangtze Block. The high temperature (B) component is prefolding with dual polarity. Unlike the prefolding paleomagnetic directions observed id eastern Sichuan, western Hubei and northwestern Hunan, the B component resolved from central Hubei indicates no significant rotation with respect to other parts of the Yangtze Block. Since one of the two sampled sections is in the strongly deformed foreland fold-thrust belt of the Qinling Fold Belt, this would seem to negate the possibility that the differential rotations observed in the border area between Sichuan, Hubei Hunan and Guizhou are associated with the collision of the Yangtze Block with the North China Block.