Conodont CAI and magnetic mineral unblocking temperatures: implications for the Western Canada Sedimentary Basin

Abstract

The laboratory unblocking temperature of a magnetic component ( T UB) is dependent on the time duration and temperature of its acquisition and thus is similar in concept to the conodont color alteration index (CAI). The CAI provides an independent determination of the past thermal history that can be related to the observed T UB. We present simple CAI versus T UB plots that can be used to determine the possibility of a thermal remagnetization in specific magnetic minerals, given the measured T UB, or alternatively, to estimate the minimum T UB necessary for a magnetization component to have been unaffected, given a specific CAI value. Failure to correctly correlate CAI values in the Cordillera on the western side of the Western Canada Sedimentary Basin may have led to secondary uplift remagnetizations being interpreted as primary remanent magnetizations in earlier paleomagnetic studies.