Date of Award
Master of Science (MS)
Bottineau interval rocks from the North Dakota part of the Williston Basin comprise a single marine transgression/regression cycle, Early Mississippian (lower Scallion subinterval) marine transgression from the restricted depositional environment of the Bakken Formation resulted in normal marine circulation, Six major facies were developed: (1) the central basin, (2) basin flank, (3) open shelf, (4) crinoidal mudstone, (5) gray shale, and (6) restricted shelf. Marine transgression continued until upper Scallion subinter val time, by which time the open shelf facies had already prograded over the gray shale and crinoidal mudstone facies.
Marine regression had begun by middle Bottineau interval (Virden subinterval) deposition. Three younger shallow water facies were developed along the margin of the basin: (1) the pelletal grain stone, (2) oolite grainstone, and (3) lagoonal. These facies pro graded basinward over deeper water facies as marine regression con tinued until, by Flossie Lake subinterval time, these shallow water facies were being deposited in the central basin area. Bottineau interval sedimentation terminated with continued marine regression and a transition to deposition of shallower water Tilston interval sediments.
Two diagenetic provinces, basin and shelf, with different dia genetic histories, were identified in Bottineau interval rocks. Dia genetic processes were post- or pre-lithification events. Prelithification processes included biologic acthity, compaction, soft sediment deformation, pyrite replacement, cementation, and neomorphism. Biologic activity occurred early, both during and after deposition, Pyrite replacement, soft sediment deformation, precipitation of fringing cement, and microstylolitization occurred shortly after deposition. Later precipitation of equant and overgrowth cements prevented further microstylolitization in cement-lithified fabrics. All pre-lithification processes ceasec once cementation and neomorphism had completely lithified the sediments.
Post-lithification processes included stylolitization, solution, fracturing, silicification, hematite replacement, dolomitization, and anhydritization. Stylolitization and fracturing began after complete lithification, as did silicification which produced chert nodules in the restricted shelf facies. This was followed by hematite replacement of matrix and allochems. Solution voids formed prior to, or during dolomitization as meteoric waters dissolved skeletal allochems. Anhydritization was the last event observed to have altered Bottineau interval rocks.
Areas of potential petroleum production exist from the L2 interval in northwestern North Dakota, from structural traps resulting from salt solution of the Prairie Formation in north-central North Dakota, and from structural and stratigraphic traps along the erosional unconformity in eastern North Dakota.
Heck, Thomas J., "Depositional environments and diagenesis of the Mississippian Bottineau interval (Lodgepole) in North Dakota" (1979). Theses and Dissertations. 131.