Wyoming The Nucleus of North America
Vložit
- čas přidán 25. 06. 2024
- Presented by Ron Frost
University of Wyoming
One can strongly argue that the North American continent grew around the Wyoming craton by accretion of rocks onto the margins of the continent. This makes the Wyoming craton the true nucleus of North America. The Wyoming Craton, along with the Slave Craton in northern Canada, contains the oldest rocks in North America. The oldest rocks in Wyoming Craton date from around 3.5 Ga (billion years old), but they contain exotic zircon grains that date from around 3.8 Ga. Some of these zircon grains have isotopic compositions that are consistent with the derivation of some chemical components from the very original crust of the Earth. Gray gneisses, (i.e. Na-rich and K-poor granitic gneiss) were emplaced between 3.5 and 3.3 Ga and are exposed across the Wyoming craton from the Granite Mountains to southwestern Montana. A sequence of metasedimentary rocks dating from 2.86 Ga likely records the rifting of the Slave Province from the Wyoming province. Granitic magmatism ranging from 2.8 to 2.6 Ga occurred across the Wyoming province, and along with the 2.7 Ga old belt of high-pressure rocks in the northern Teton Range, record the earliest evidence of plate tectonics in North America - as well as some of the earliest plate tectonics anywhere on earth.
Between 1.7 and 1.8 Ga the Wyoming Craton, the Slave Craton, and other Archean cratons with a younger history were stitched together by deformation zones to produce Laurentia, the Precambrian core of North America. North America grew by extensive magmatism at 1.4 to 1.5 Ga, which was followed by the Grenville orogeny a major mountain building event that occurred around 1.1 Ga and extended from Labrador to Texas. The Grenville orogeny records the collision between Laurentia and protocontinents of Europe and Africa. It is very similar to the Appalachian orogeny, which occurred on the eastern margin of North America in the Permian (a mere 300 million years ago). The assembly of North America was completed during Cordilleran orogeny, which occurred along the western margin of the continent in the late Cretaceous to the Eocene (between 65 and 50 million years ago), and which formed nearly all of present-day Wyoming’s mountains and basins. This involved accretion of island arcs from the Pacific onto the western margin of North America.
Your channel is a treasure! Yeah, not all splashy and flashy, just intelligent and incredibly informative if you are truly interested in geology! Thank you so very much.
Very interesting talk, and I do not pretend to understand it all, but it really expanded my thinking about the North American Craton. I will definitely be watching this again and taking notes. Loving this channel!
Great presentation Ron thank you.
Great talk! Thanks!
Thank you Ron! So informative
nice explanation
layers and layers of melted rocks, some very recent says lots about the reality of catastrophic meteorite impacts
I would have thought that the Superior Province was more the nucleus of NA.
Find CZcams channel "Steven Baumann". He supports your idea.
Could have been rehearsed.
What's the mitochondria of North America? 🤔
the world gets struck by meteorites more frequently than folks want to admit hahahahahaha and these time scales are meaningless at the geologic scale, we are not even a going concern
Calgary is at 1000 m not feet ( 3500 ft )
Calgary ; 1,045 m (3,428 ft), in USA ft and in CA m
It’s metros in Spanish, Raspberry, so what’s your point? Scroll on…
The nucleus of NA (Laurentia) is the Superior craton. Wyoming is merely a southwest add-on. Sir, are you supposed to be a geologist? If it's that so you've got to throw out your ugly biases! I'm really not impressed!