Introduction to the Williston Basin
The Williston Basin is an intracratonic sedimentary basin that occupies the majority of North and South Dakota, as well as, parts of Wyoming and Montana. The basin also stretches in parts of Canada, but this report will be focused on the United States portion of the basin. This portion of the basin is generally flat with average elevations ranging from 1500 feet to 3000 feet. Precipitation in the basin area ranges from 15 inches to 20 inches per year. The temperature averages approximately 65-70 degrees during the summer months, and 10-20 degrees in the winter.
Deposition of sediments began in the basin during the Cambrian era, but subsidence and basin filling occurred the most during the Ordovician,
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This geologic data has shown that the basin contains sedimentary rocks of Late Cambrian to the Tertiary age, and is more than 15,000 feet thick. The depo-center of the Williston Basin started its development during the early Paleozoic era in the northwestern part of North Dakota. The sedimentary rock thickness decreases to less than 10,000 feet in eastern Montana and to less than 5000 feet along the basin margin (Peterson & MacCary, 2009). Carbonate deposition occurred throughout the area during the early to middle Paleozoic era and changed to clastic deposition in the late Paleozoic era. During the Paleozoic era, more than 8000 feet of marine sediments accumulated at the basin center, but the shape of the basin remained the same. The basin depo-center has however shifted slightly over time. The Williston Basin sedimentation in the lower and middle Paleozoic is dominated by carbonates and evaporates, whereas upper Paleozoic and younger rocks are largely siliciclastic with small admixtures of carbonate (Anderson & Gerhard, …show more content…
The formation is located in western North Dakota, southern Saskatchewan, northeastern Montana, and southwestern Manitoba, and has a depth of approximately 130 feet to 12,000 feet deep. The upper and lower Bakken shale layers contain large amounts of organic-rich black mudstone. During the Lower Bakken Member deposition, an increase in the rate of siliciclastic sedimentation (quartz and orthoclase feldspar) caused more organic material to be preserved in bottom sediments. During Upper Bakken Member deposition, an increase in biological productivity in the water column resulted in more organic carbon reaching the bottom where it was subsequently preserved (Bustin & Smith, 1995). The middle layer is made up of mostly mudstone and sandstone. This layer can be tapped by both conventional and continuous oil
One of the major things noticeable from the cross section is that quite a few of the rock layers are over turned, where the older rock layers are above the newer rock layers. This is seen in the contact between the Quartz Monzonite of Papoose Flat and the Campito Formation which is also a disconformity. Next there is some fault zones separating the Camptio, Poleta, and Harkless formations. We then see some more overturned layers with the contacts between Saline Spring Valley Formation (lower and upper members) above the Mule Spring Formation along with some inferred folding. With a normal fault separating the inferred folding event, we see where the overturning occurs. In between the Cambrian layers we see Tertiary Basalt nonconformities also being folded, thus with that we know that the folding event was more recent than the formation of the Basalt. Next there is a large Basalt field with a spot of the Harkless formation. Again we see over tuning as the Basalt field ends there are the Devonian and Mississippian rock Layers on top of the basalt. Separating these overturned layers from the Harkless Formation and the Saline valley Formation (upper member), which are not overturned, is a thrust fault. From this information, there was a major stress event sometime after the Tertiary period causing the rock layers to fold and overturn. And from this stress event and from the folding, normal and thrust faults are formed. Finally we see that there were alluvial and landslide deposits from the Quaternary after the folding, faulting, and over
This formation is a very fine grain Mississippian limestone. To test to see if this was the Bangor formation we used HCL and because there was a reaction we know its limestone. This formation could also be described as gray in color as well as an average thickness of 700 feet. We see the Bangor until stop eight, where we see a very different vertical bedding. Also different at stop eight is the outcrop no longer reacts with HCL. From this we gathered that we had moved into the Hartselle formation. In the Hartselle Formation, Mississippian aged sandstones are dominant. This particular stop had a large amount of jointing. After the Hartselle, we figured the Pride Mountain Formation would be next, however at stop nine we see the Maury Formation present. This stop focused on the rock located inside the creek. Because we were unable to go into the creek to get the strike and dips, we once again had to do a projected orientation. Also found on this stop were natural sulfur springs, easy to notice with the smell that it gives off. The Maury formation consist of Mississippian- Silurian aged shale. At the next stop, stop 10, we encounter the Ft. Payne formation. Although this area location was thickly vegetated, we were able to conduct the acid test and saw that the HCL reacts in some places but not all. From this we concluded that this was the cherty limestone of the Ft. Payne formation. The following stop, 12, we went up section and arrived at the Maury Formation once again. At the final stop, location 13, we see Ft. Payne Formation. All of the metamorphism and deformation in the southernmost Appalachians can be related to the movement of the thrust sheets and stacks (Higgins,
The Mesozoic tectonic history of the North American Cordilleran region is very complex and involves:
Starved Rock State covers about 200 miles and some 470 million years, from Ordovician sandstones to Pleistocene glacial till. The Ordovician St. Peter Formation sandstone was deposited across the midcontinent during the second major marine transgression of the Paleozoic Era. The first transgression deposited Upper Cambrian to Lower Ordovician clastics and carbonates. The clastic to carbonate rock transition is consistent with gradual sea level rise over the North American craton. Sea level dropped late in the early Ordovician, exposing the carbonate strata to processes of cave development.
The climate in this region consists of sweltering summers with temperatures near 100 degrees Fahrenheit and chilly winters with temperatures ranging to the low 40s. Abrupt and rapid weather swings are also common, temperatures can drop 50 degrees in a day. The Edwards Plateau does not have a wet or dry season, 1-2 months without rain can occur at any moment. It has a consistent humidity with it being usually at 70%, but lowers in the winter and
In the Fayetteville Shale area. This is the area in North Central Arkansas that sits above the Fayetteville Shale, a rock layer that contains natural gas. This mostly rural area has been turned into a busy industrial zone. Companies are also currently fracking test wells in the Brown Dense, a layer of rock in Southern Arkansas.
During the Eocene epoch, 47,000,000 years ago, one of our ancestors lived in what is now Germany. She was still young, her baby teeth still intact and probably less than a year old. This little girl came to a lake’s edge for a drink of water; cupping the water with her hand she slowly drank the water while holding onto a branch with her other hand. Our ancestor died there when she was overcome by an underground gas bubble that erupted, the fumes leaving her unconscious; she fell into the water and drowned. Her body slowly drifted to the bottom of the lake with a myriad of other creatures. The lake where she was buried eventually filled with mud and algae that turned into oily shale
Approximately 17 meters thick, Unit A defines the lowest third of the Juniata Formation. Fragments of marine fossils, including bryozoans, brachiopods, and gastropods, are commonly found in the bottom-most portion of this unit of structureless mudstone and quartz arenite. Quartz grains in the sandstone beds of Unit A are typically immature and fine-grained, though the sandstone packages tend to coarsen upwards. Though typically structureless, intermittent bedding of the sandstone and shale packages is observed in this unit, and some areas display
This Lower Keg River member was initiated by a rapid increase in sea level elevation flooding the salt plains of the Contact Rapids. Campbell (1987) described the Lower member of a dark micritic limestone, in a somewhat “euxinic” environment, containing bitumen and fauna such as brachiopods, crinoids, corals, stromatoporoids and gastropods. The unit can be locally dolomitized with a maximum thickness of approximately 50m. The Upper Keg River member was deposited during the restriction of marine waters by the Presqu’ile Barrier reef into the Elk Point Basin (Campbell, 1987). The interior of the basin contains Upper Keg River pinnacle reefs, banks and platforms. Campbell (1987) noted the spatial differences in the type of carbonate deposition within sub-basins; areas from the Peace River Arch to southern Alberta show a fringing carbonate platform, while the Rainbow, Zama and Shekelie basins contained the majority of the
During the Pinedale glaciation, there were two ice sheets. One of them being the Cordilleran Ice Sheet. The Cordilleran Ice Sheet was comprised of three main lobes. The Puget Lobe, Okanogan Lobe, and the Purcell Trench Lobe. The one lobe in Northern Idaho, near present day Lake Pend Oreille, was the Purcell Trench Lobe. When these sheets of glacial ice moved south they caused an ice dam to occur. J.T. Pardee states that “The evidence of icebergs, together with the apparent regency of the lake and the variable height of its surface, connect this lake with the glacial period, and readily lend themselves to the suggestion that its dam was of ice” (Pardee, 1910) This ice dam blocked the Clark Fork River which is near the boundary of Idaho and Montana. The water from the river was blocked and began to build up and formed Glacial Lake Missoula. Water
The western Cordilleran orogenic belt had been depicted as a passive margin after Neoproterozoic to Early Cambrian rifting. Afterwards, the passive margin converted to an active margin most probably about Late Devonian to Late Cretaceous through the subduction of the exotic allochthons beneath the North American plate. The late Jurassic to Cretaceous subduction of (Sevier and Laramide Orogeny) representing as a period of the back thrust, intraplate thrusting, behind a magmatic arc on the upper plate near or on its westernmost margin from the latest
The Colorado River Basin starts in the Rocky Mountains and cuts through 1500 miles of canyon lands and deserts of seven US states and two Mexican states to supply a collection of dams and reservoirs with water to help irrigate cropland, support 40 million people, and provide hydroelectric power for the inland western United States [1,2]. From early settlement, rights over the river have been debated and reassigned to different states in the upper and lower basin; however, all the distribution patterns lead to excessive consumption of the resource. In 1922, the seven US states signed into the Colorado River Compact, which outlined the policy for the distribution rights to the water [3], however, this compact was written during an exceptionally
First, we must examine the sedimentary formations; when they were formed, how they were formed, and what materials they consist of. About ninety-three to one hundred million years ago, the Western Interior Seaway rolled through the North American continent, eventually reaching the geographical area of today’s Mesa Verde National Park (National Park Service 2005). This sea deposited a thick, hard sandstone base that is called Dakota Sandstone, although this layer is not exposed in the park
deposit is the Marcellus Shale, located in the northeastern part of the US, centering on the state
The oldest rocks found in the Death Valley region were formed in the Precambrian time period no more than 1.8 billion years ago during the latter half of the Proterozoic Eon. The rocks are seen on the steep face of the Black Mountains above the current area of Badwater and were formed via deposits of mud and sand from an ancient volcanic mountain belt. Sometime between 1.8 and 1.7 billion years ago, the volcanic and sedimentary rocks were severely altered when chemical or structural changes occurred because of intense heat or pressure from the Earth's core. Because of this process, any fossilized information about the region was lost making it impossible to truly understand the origin of the region. There is some debate on whether basalt or schist was the original and dominate rock in the region before it was transformed into contorted gneiss, but again, there is no way to prove either theory.