NSERC grants at Laurentian University Subventions du CRSNG `a l ...

80Darrel LongPrecambrian and Early Paleozoic RiverA grant of $26,690 per year.Une subvention de 26 690 $ par année.Discovery Grant – Subvention à la découverteThe objective of this research is to understandhow and why the deposits of Precambrian and EarlyPaleozoic river systems differ from those that formedafter the advent of rooted plants. Many ofthe processes that influenced these systems were significantlydifferent from those of the present. Forexample the lack of sediment binding, baffling, and trapping by plant rootswould have promoted flashy surface run-off, lower bank stability and fasterrates of channel migration. It has been suggested that some pre-vegetationrivers were tens of kilometers wide, but this has yet to be confirmed in outcropstudies. In this study the three-dimensional character of pre-vegetationsandy and gravelly river systems will be investigated by examination usinglaterally extensive (> 1 km) lake, sea and canyon side exposures of the PaleoproterozoicFair Point Formation and Martin Group (SK); and the EarlyPaleozoic Bateau Fm (NFDL). Sandy fluvial systems will be investigated inthe upper part of the Paleoproterozoic Athabasca Group (SK); the MesoproterozoicMackenzie Mountains Supergroup (NWT); the NeoproterozoicSignal Hill Group (NFDL), and the Early Paleozoic Blanc-Sablon memberof the Bradore Formation (NFDL). Further Proterozoic examples and moderndry-land systems will be examined in the Flinders Ranges of Australia.Studies of modern rivers using ground-penetrating radar have indicated thatthe internal geometry of in-channel bars in large braided rivers can be usedto model accretionary depositional processes on a bar and reach scale. Asimilar architectural approach will be used to determine the characteristicsof the pre-vegetation systems in order to develop a spectrum of models thatcan be used to facilitate understanding of terrestrial depositional processesbefore the advent of land-plants. These models may be of economic use inunderstanding heavy-mineral distributions and the influence of permeabilitybarriers on the reservoir characteristics of Precambrian and Early Paleozoicfluvial sand bodies.