Triassic-Jurassic of Alberta, Saskatchewan, Manitoba, Montana, and North Dakota

摘要: Triassic sedimentary rocks in southern Saskatchewan, North Dakota, and Montana represent only Early time. Thicknesses excess of 700 ft western Dakota reflect the depocenters restricted salt basins. On basis lithologic correlation, Lower Watrous Formation Saskatchewan is equivalent to upper part Spearfish Dakota. Lower, Middle, Upper Alberta are marine origin, produce oil gas, reach thicknesses 4,000 ft. Jurassic widespread because seas transgressed from northwest along trough into Montana, then spread east across Williston basin. strata southwestern Alberta. Middle most widespread, thicker than 500 a depocenter southeast Similar present eastern trough. also 7,000 thick more Montana. Coal, gypsum, oil, gas commercial quantities formations. Oil significant, particularly north-central where 20 fields estimated have ultimate production 411 million bbl. These primarily stratigraphic traps sandstone.