New Early Triassic paleomagnetic data from Huangben section, Guangdong and its tectonic implications

A paleomagnetic study was carried out on a total of 122 oriented cores from Daye Formation of the Huangben section, Guangdong Province. Rock magnetic investigations show that low-titanium magnetite is a dominant carrier. Detailed progressive thermal demagnetization isolated 2-3 components. The low temperature component clusters around the present geomagnetic field direction. An intermediate temperature component is isolated at 100-400 degrees C and is interpreted as a Yanshanian remagnetization. A high-temperature characteristic remanent magnetization (ChRM) is obtained at 400-530 degrees C with D =51.1 degrees, I=15.3 degrees, alpha(95)=5.0 degrees and passes generalized fold test and reversal test, suggesting high temperature component is a primary remanence. Its correspondent pole position is 38.5 degrees N, 212.7 degrees E (dp = 2.6, dm = 5.1), which overlaps contemporaneous pole of Yangtze Block at 95% confidence level. Therefore, we believe that Huanan and Yangtze blocks were not separated in the Early Triassic. Compared to other published Early Triassic paleomagnetic data from Huanan Block, the inclinations are very close but the declinations are greatly variable. In stereo-projection, all the Early Triassic poles from Huanan Block lie along a small circle around the Huanan Block, implying that local micro-blocks rotations lead to the inconsistence of Early Triassic paleomagnetic directions.