Field and laboratory investigations into remagnetizations and remanence acquisition

点击翻译按钮获取中文摘要

Paleomagnetic and rock magnetic studies of sedimentary basins have proven to be significant sources of information on subjects as diverse as the origin of ore deposits, the development of reversal time scales and past climate variation. As such, the importance of understanding the geologic and environmental processes that have created, modified and destroyed specific magnetization components within a basin cannot be overstated. The applicant's previous paleomagnetic and rock magnetic studies have focused on Ordovician- Mississippian carbonates of the Williston Basin in central North America. Such carbonates have provided significant information; however, they typically have weak natural magnetizations, and carry one or more secondary magnetizations that may or may not be associated with specific diagenetic events. To complicate matters even further, if the secondary magnetization is unrecognized, our understanding of the processes that occur in the basins may be affected. The studies proposed are aimed at reducing and constraining these complications, even as they continue to examine the traditional hypotheses on the origins of remagnetizations in sedimentary rocks, investigate remanence acquisition mechanisms, and evaluate some additional possible factors in remagnetization. Three new approaches to the long term objectives are being proposed: the past paleomagnetic studies of the Williston and Western Canada Sedimentary Basins will be extended to younger, clastic rocks (Cretaceous Viking Formation and equivalents), experimental investigations on the potential for fluid / temperature interaction effects on remanence acquistion and potentially remagnetization will be conducted; and a close examination of the impact of specific diagenetic events on magnetization will be performed. These studies will allow continued construction of a continental-scale synthesis and database of the distribution of remagnetizations in the Williston and Western Canada Sedimentary Basins that aims to evaulate the controlling factors on remagnetization and remanence acquisition in sedimentary basins.