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The Flag of Moab: Ancient Oceans, Oil, and Mountain Mountains – Moab Sun News

More than 65 million years ago, a sea route existed across North America from the present-day Gulf of Mexico to present-day Alaska. Peter Flegg is a research scientist at the Office of Economic Geology in Austin, Texas, who has studied the geology of this seaway by looking at sediments from the southwestern United States to Canada and Alaska. We spoke with Flegg about the fringes of this sea lane that includes parts of the present-day Colorado Plateau.

Science Moab: Can you talk a little bit about the Western Inland Sea Route, the prehistoric ocean across western North America?

Flig: [The Western Interior Seaway was] A sea route cut through the continent and then eventually disappeared. It was hundreds of meters deep, but not as deep as the continental shelf. There were sediments that were coming out of the formation of the Sevier Mountains. The Orogenic Severe Belt twisted the lithosphere and created this large inland basin along the water-filled continent. In this inland sea passage, sediments from rivers and floodplains enter as deltas and shorelines along this complex coastline that stretches throughout North America. Section of the sea route Laramidia from Appalachia. [Laramidia was a landmass that stretched from modern-day Alaska to Mexico. -ed.]

The science of Moab: How has the shoreline and water level of the sea lane changed over time?

Flig: You will have fluctuations in sea level from tens to hundreds of metres. The beaches moved towards the center as the seaway narrowed and then was reinforced as the seaway rose, creating lots of different depositional environments stacked one on top of the other. You might start with a very broad seaway in one place with deltas, beaches, and even marine sediments. As the sea route shrinks, those beaches are moving to the east [and in that location] Coastal plains are forming on top of those ancient beaches, so you now have trees in peat bogs and river systems and the dinosaurs that lived on those coastal plains. As Seaway expands again, [that location would again] Back to more marine conditions.

The flag of Moab: Mancus rock is one of the deepest parts of the basin, is that right?

Flig: Think of the Mississippi Delta: If you were to walk on the actual aerial portion of the delta and start walking into the Gulf of Mexico, the far front of the delta. Eventually, you’ll be hundreds of meters out of the water where you’ll lose all the coarse-grained sediment, like sand. You just deposit silt and mud. The Mancos Shale is that deepest part of the system, you’ve bypassed all the inputs to a true coarse grain sediment and you’re just depositing those very fine silt and clay. That’s a big part of the aquarium, and it logs a lot of time.

The Flag of Moab: Is There an Economic Value for Seaway Deposits?

Flig: The oil and gas industry cares a lot about the Seaway deposits, because the rocky outcrops are amazing. When people drill oil and gas reservoirs, they have a view of Swiss cheese going underground. These wells may be widely spaced and core drilling very expensive. Book Cliffs can provide us with a protrusion counterpart to these subterranean reservoirs. It’s not that they are necessarily cabinets; They could be, but they represent what we cannot see underground. What might be a good tank and how well it communicates over long distances, Book Cliffs provide us with that continuous exposure.

Science Moab: What first brought you to study Seaway?

FLIG: Well, the Bureau of Economic Geology was looking for someone to come out and look at these outcrops as analogues of reservoir systems. One of the best places to do this is Book Cliffs, so I only initially started using these as cantilever counterparts for cabinets for people all over the world. Then I became very interested in the Seaway deposits as to what kind of plants and animals they keep, what they could tell us about the evolution of the interior of North America, and the natural things that happened to this planet based on waxing. dwindling glaciers. What does it look like when humans aren’t around? We want to understand if we’re doing something with the planet and causing sea levels to rise or temperatures to change.

Science Moab: What is your passion for studying in connection with the sea route?

Flig: I’m really interested in what’s going on with the deposits. It is very interesting to look at deposits to see why they have the characteristics that they do. The properties of these systems then speak to their broader geometries in the subsurface, where shale is found. For example, in Alaska, a lot of these systems go underground and there are very active oil and gas reservoirs. I’m really interested in looking at the spurs of these systems and understanding how these properties change, and then predicting whether we’ll see the same things in the Earth’s interior and asking if we should change our expectations about what’s really going on.

Science Moab is a nonprofit organization dedicated to engaging community members and visitors with science happening in southeastern Utah and the Colorado Plateau. To find out more and hear the rest of this interview, visit www.sciencemoab.org/radio. This interview has been edited for clarity.


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