The paleomagnetism and U–Th dating of three Canadian speleothems: evidence for the westward drift, 5.4–2.1 ka BP

Abstract

Three speleothems from western Canada have been analyzed for their paleomagnetism and U–Th activity ratios. These cave deposits do not appear to show the kind of depositional effects on the recorded magnetic signal as is often the case with sediments. In addition the signal may be referred directly to geographic coordinates so that virtual geomagnetic pole plots may be constructed. This in turn has allowed assessment of any possible bias of the paleofield.The U–Th activity ratios of two flowstones from the Crowsnest Pass area of British Columbia indicated ages greater than the 350 ka dating limit of the dating method. One of the samples was reversely magnetized. Besides their use in the study of the ancient field, these samples have useful geomorphic applications. A stalagmite from Vancouver Island was shown to have recorded [Formula: see text] clockwise loops of the field vector in the period 5.4–2.1 ka BP. This implies a mainly westward drift of the paleofield for this period; the corresponding VGP's were mostly far-sided and slightly left-handed.