PALEOMAGNETISM OF PERMIAN RED BEDS FROM SOUTH KAZAKHSTAN - DRM INCLINATION ERROR OR CRM SHALLOWED DIRECTIONS

Thermal demagnetization of palaeomagnetic samples from Upper Permian red beds from south Kazakhstan yielded almost noiseless data. In seven samples that show rectilinear decay to the origin, the tilt-corrected mean direction of the characteristic component is D = 217 degrees, I = -44 degrees (K = 81, alpha(95) = 6.7 degrees). Most samples, however, reveal curved demagnetization paths and steady shift of vector endpoints on stereonet. For the latter samples, the NRM is accounted for by two components with similar declinations and different inclinations. The first tightly grouped component is an overprint and its mean inclination is close to the reference direction for stable Europe and to that for samples with rectilinear demagnetization plots. The second high-temperture component is more dispersed and about 15 degrees shallower than the first one. Maximal K-max and intermediate K-int axes of anisotropy ellipsoids gravitate to the stereonet equator, whereas many K-min axes are vertical. Rock magnetic studies revealed haematite as the only remanence carrier in these rocks. We argue that the shallow inclination of the high-temperature component has not resulted from horizontal transport of the area, but is due to NRM acquisition process. One possibility is to assume that the most thermally stable component of detrital origin has inclination error and is overprinted by a component of chemical origin. Also, we discuss a model of time-distributed CRM acquisition and attribute the inclination shallowing to diagenetic compaction.