Late Cretaceous paleomagnetic results from southeastern China, and their geological implication

A paleomagnetic study was carried out on late Cretaceous red beds in central Jiangxi Province, southeastern China. Stepwise thermal demagnetization was used to isolate the characteristic higher temperature component (HTC) from the Jishui (D = 355.7°, I = 34.8°, α95 = 6.3°) and Ganzhou (D = 15.6°, I = 35.6°, α95 = 5.5°) areas, respectively. The HTC direction from the Jishui area passes Enkinʹs fold test at 95% confidence level, and indicates an 18.9° ± 5.5° counter-clockwise rotation relative to the referent pole of the stable South China Block (SCB). The HTC direction from Ganzhou passes both McFaddenʹs fold test at 95% confidence level and reversal test. Comparing these two new poles (81.0° N, 322.2° E, A95 = 5.8° from Jishui, and 74.4° N, 225.1° E, A95 = 5.2° from Ganzhou) with other coeval poles reported from South China, these results demonstrate a significant difference in paleolatitude (9.9° ± 4.1°) between coastal and inland areas, which might be either related to dextral shearing faulting between them or inclination shallowing conducted by sedimentation and/or compaction. However, results obtained from both anisotropy of the isothermal remanence (AIR) method and corrected results of the elongation/inclination model of Tauxe and Kent [L. Tauxe, D.V. Kent, A simplified statistical modal for the geomagnetic field and the detection of shallow bias in paleomagnetic inclinations: was the ancient magnetic field dipolar? In: J.E.T. Channell, D. V. Kent, W. Lowrie, J. Meert (Eds.), Timescales of the Paleomagnetic Field, Geophys. Monogr. Am. Geophys. Union, 145 (2004) 101-115.] indicate that a distinct inclination flattening occurred in our samples.