On remagnetization problems in palaeomagnetism

Palaeomagnetic properties of igneous rocks in relation to their thermal history are discussed. Owing to a longlasting and complicated thermal history of most igneous formations it is suggested that in general the original thermoremanence has been replaced by a viscous build-up at moderate temperatures. Following this suggestions it seems impossible to establish a magnetization/time relationship within most igneous units rendering several potential palaeomagnetic and geological applications of rock magnetism unlikely to apply. It appears that under certain circumstances remagnetization may upset the original direction in a very complicated manner. Finally, the remagnetization theory may provide a satisfactory explanation of the apparent petrology/polarity correlation.