Paleomagnetic reconnaissance of early Mesozoic carbonates from Williston Lake, northeastern British Columbia, Canada: Evidence for late Mesozoic remagnetization

Three classic sections of Middle and Late Triassic fossiliferous limestones cropping out around Williston Lake in British Columbia, Canada, were sampl ed for paleomagnetic study. The objective was to test the suitability of th ese units for detailed magnetobiostratigraphic study with the aim of improv ing the reference Triassic geomagnetic polarity time scale. The Williston L ake characteristic magnetizations differ, however, from any Triassic North America cratonic reference directions. A satisfactory agreement is found in stead with Cretaceous - early Cenozoic North America cratonic reference dir ections. The exclusive occurrence of normal polarity suggests that remagnet ization likely occurred during the Cretaceous long normal superchron. Remag netizations may have been triggered by connate brines, which moved along aq uifers of porous sandstones and carbonates in the early stages of Laramide folding.