DISCORDANCE OF JURASSIC PALEOMAGNETIC DATA FROM SOUTH CHINA AND THEIRTECTONIC IMPLICATIONS

We have collected oriented cores in Jurassic redbeds from two areas in southern Guangxi Province. Stepwise thermal demagnetization of the sa mples and subsequent statistical analysis show that the stable magneti zation from both areas is a near-primary chemical remanence that passe s the fold test. Area 1 lies in a shear zone and is rotated 24-degrees +/- 12-degrees counterclockwise and insignificantly displaced 4-degre es +/- 12-degrees northward with respect to Area 2, which lies outside the shear zone, 80 km to the northwest of Area 1. After adjusting for a post-Jurassic tectonic rotation identified in a previous paleomagne tic study, the pole for Area 2 is indistinguishable from an averaged E arly to Middle Jurassic reference pole for the Yangtze craton, suggest ing that this area was joined to the Yangtze craton by that time, and confirming that considerable clockwise rotation of south China relativ e to north China remained to be accomplished before the present config uration of the two blocks was attained. In combination with geological observations, these data support a terrane model based on sinistral s hear acting parallel to recognized structural trends in this part of s outheast China during post-Triassic time.