The Hit-and-Run Model for the Sevier & Laramide Orogenies of Western North America
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- Опубліковано 14 кві 2023
- Speaker: Basil Tikoff, Ph. D., Professor of Structural Geology Department of Gescience, University of Wisconsin-Madison
- Наука та технологія
Basil is amazing. I always like listening to him.
As a lay-geologist, I wonder why any geologist would consider fixist theory when you can see real time in human years the mobility of the west versus east side of the San Andreas. I didn't realize the importance of the Mount Tatlow study until I saw your video, Dr. Tikoff. It is fascinating to me to see a paradigm shift real time! Excellent presentation of the Hit and Run theory.
Excellent presentation. Your lectures are so clear and easy for lay folk as well as geologists to understand.
These dates are quite fascinating as they relate to the Ontong Java Nui hypothesis ("New evidence for the Ontong Java Nui hypothesis" Tejada et al. 2023 paper for example). Ontong Java Plateau is proposed to have formed as a single unit with Manihiki and Hikurangi Plateaus at 125-120Ma, and to have broken up 118-86Ma, with the plateaus moving apart from one another from 86-40Ma.
It is further worth noting that the Pinon Formation in Ecuador is considered to be a piece of the Manhiki Plateau that is proposed by Reynaud et al. in their 1999 paper "Oceanic plateau and island arcs of southwestern Ecuador: their place in the geodynamic evolution of northwestern South America" to have "not been transported passively by the oceanic plate during the whole 123-80Ma tie-span. Therefore, the hotspot responsible for the generation of the Pinon Formation may have been located closer to the Ecuadorian margin." In other words, there is evidence to suggest that a component of the Ontong Java Nui plateau complex was in the region of Ecuador, and thus the Ontong Java Nui complex also has evidence that it formed nearer to the western margin of South America than present models indicate.
This would put the OJN complex much nearer also to the area where all these terranes in Baja-BC proposals are generally originating from. There is thus a high probability that there is a very important relationship between the OJN formation, its breakup, and its spreading apart, to the "hit-and-run" motions of terranes in western North America.
This connection really strains the plausibility of plate tectonics, however. It, instead, is far more readily explained as part of an earth expansion model. In fact, it is possible to interpret the entire magnetic anomaly map of the Earth as being the result of undercurrents below the crust that flowed in all directions (from the area of Eastern Pakistan as a location where they erupted from the mantle itself) and this brings to light a highly anomalous but revealing structure in the area of Fiji--between the OJP, MP, and HP's. Namely, a high magnetic intensity anomaly in an oval shape that is surrounded by a "Figure-8" structure to the east and west. Below it and above it are additional peculiarities, but most significantly coming out of its northern section is a "fracture zone" like structure that goes in a straight line upward and then branches off like a trident shape. To the left of this is the OJP while to the right is the MP and the main conduit--if positioned along the western margin of North America at an earlier time in Earth's expansion history--that goes upward would provide a mechanism for why these terranes were caused to "hit-and-run" North America.
In addition, the flow seemingly caught at the bend from BC to Alaska, which would help explain the clockwise rotation of North America as well.
There is much more evidence to these concepts than can be put into a quick comment on a UA-cam video, but, regardless of the model being incorporated, the relationship of the formation and breakup and separation of the Ontong Java Nui complex is unequivocally related to the accretion of terranes onto northwestern North America's margin.
Absolutely great thanks Basil.
I'm in Washington and have wached all the Zentner's series.
This is great because it explains what I've been looking at for 50+ year's and the complication I'm now getting a grasp on.
I'm even thinking of some courses to get some of the definitions locked in.
First heard of that model 2 days ago from a lecture from Nick Zentner. Fascinating how new (or in this case: partly old) evidence can overturn what was thought to be common wisdom. Lets hope that more evidence can be collected and the issue can finally be laid to rest.
I think the animation of the Hit-n-Run model that I saw on Nick's channel was awesome. I don't remember who did it or if it is in the presentation that featured Basil.
I have driven most of the Rockies within the US and am always amazed when I find someone talking about how they were formed. I grew up on a ranch up the Skalkaho in the Bitterroot Valley (Hamilton) Montana. We had cattle and I got to ride a horse deep into the mountains and saw many things that made me wonder how it was formed.
I truly appreciate how these geologists freely give us their time!
Wow that was so amazing so much research has been done. by so many knowledgeable geologists.
Really awesome presentation by Dr. Tikoff! I just saw Nick Zentner's presentation on the Hit-and-Run model and was hoping to learn more about it and then low and behold this pops up in my recommended videos 😁
Great talk and great questions.
Excellent presentation thank you very much
This is totally awesome. It cleans up confusion about the Salinian block being in between the Franciscan and Nacimiento blocks. Some thought there could have been over a hundred miles of sinistral motion along the Sur-Nacimiento fault on top of SAF dexteal motion. That seemed like a ridiculous explanation to me. Another explanation was that the Salinian block squeezed into the Franciscan/Nacimiento accretionary wedge, from a southern california/mexico origin point where the granite batholith fit to the southern end of the sierras. That was also clunky. The hit and run model basically claims there was a much broader accretionary wedge and the northward shearing of the insular subcontinent slid the Salinian block and Nacimiento block up along the central coast of california *prior* to SAF displacement
The West Coast Baha-BC story is becoming established science. But the story of the Colorado Rockies still seems hand wavy to me. Then East of there we have an ocean. All are different parts of the same story. Who is going to tie it all together?
The Stuart Batholith and Swakane Gneiss are both in central Washington state, not northwest WA.
According to this, what exactly was responsible for the building of the Southern Rockies in Colorado?
This is great, and i'm gonna have to watch it several times to fully understand it. I just wish people would learn how to pronounce Nevada, It's not Nevaaaaaaaada.
Don't quite see how block uplifts form in this model.
44:30 I think this is where he addresses this. Although I'm also not 100% understanding it. But it seems like the crust sinusoids because of the collision, and this creates a push up effect which uplifts those blocks. Might need to watch this bit of the presentation a few times to understand it.
He showed that there would be synclines and antisynclines from a convergent margin that would propagate along the mantle.