Evolution of the Midcontinent Rift

Here I go through a model of the formation and subsequent failure of the Midcontinent Rift (MCR) in North America, through the Lake Superior Basin. From Ontario through, the UP, and into Wisconsin.

[@alanjohnson2613]

My geology teacher at michigan tech in houghton mi, taught about 50 years before this I am surprised she didn’t explore more and question the geology at that time.

[@christinearmington]

Great town, Houghton! 🤩

[@peggieincolfaxca3818]

I remember the Keewanaw peninsula as one of the prettiest places Ive ever been.

[@jimireland7299]

Thank you Steve Baumann, has anyone considered the MCR structural history as a companion to the Ottawa- Bonchere (sp?) failed rift system and the St. Lawrence structure to the east? What a fascinating part of the world! Always wondered about the linkage, if any, during my time in Cobalt.

[@stevenbaumann8692]

Good question. Yes they have. But likely there isn't one. The MCR is 1.1 billion years old and an entire failed rift system during the assembly/break up of Rodinia. Lawrence is an aulacogen from the break up of Pangea

[@quantumcat7673]

The Saint Lawrence rift system is a half-graben created during the precambrian during the opening of the Iapetus. Ref : Cambridge University press, Kumarapeli, 1985.

[@Double0pi]

Very informative, thanks! Reminds me that it's been way too long since I had to use a QAPF diagram, so I loved that you worked that with the structural stuff.

[@stevenbaumann8692]

Thanks! I love structural geology. I great professor. I had a video where I walk you through how steronets actually tie into an outcrop to show they do work. But it's on my reachable account.

[@slkzil]

Hello! I am new in Oklahoma. I was watching a video and somebody pointed out to me, that Oklahoma is from an geological standpoint interesting. Than somebody else mentioned MCR… I myself saw the Wichita mountains and thought „ ice age Muräne“ , like in Missouri. I called it the roller coaster country. You should drive an old, long car over those hills.. Anyway, great video. I saw, how far down your map goes. Thank you 🙏 very much. Greetings from Oklahoma

[@stevenbaumann8692]

Thanks for watching! Sorry it took me so long to respond.

[@billwilson-es5yn]

The MCR extends thru Kansas and into Oklahoma and produces tremors on occasion. Then there's another failed rift in Oklahoma that runs SE to NW by the Arbunkle and Wichita Mountains. It was formed around the same time as the Reelfoot Rift (New Madrid).

[@seaxofbeleg8082]

Do you have any video covering the New Madrid seismic zone? I am curious about its origin.

[@stevenbaumann8692]

Alas. I do not. I don’t even know much about it 😞

[@billwilson-es5yn]

​@@stevenbaumann8692New Madrid sits on top of the failed Reelfoot Rift. There's another failed rift in SE Oklahoma.

[@The_CGA]

It’s my understanding that now the hypothesis is, post-rodinia, Amazonia rifted from laurentia and the third arm of the rift was the MCR

[@thirstfast1025]

I learned lots of things. Thank you! Lol, in my whole rock collection, I have one feldspathoid. And I don't know where it came from.

[@stevenbaumann8692]

Thirst Fast I’m glad you enjoyed it! It means a lot. I love the geology of the Lake Superior region!

[@wwoods66]

So the rifting failed because Laurentia was caught in the middle of the assembling bits of Rodinia?

[@stevenbaumann8692]

Essentially. Specifically because of the Grenville’s accretion to it. However, some people have questioned this w/in the past 5 years. Some people think that it may have been partially successful. Just not here. Although intriguing, they have not really put forth any specifics.

[@davidchurch3472]

were the directional arrows on the faults in the correct directions?

[@stevenbaumann8692]

They were supposed to be. But relative to one another. It's possible I could have screwed up on one. But this is a big picture concept. It's not meant to be exact and detailed.

[@GregInEastTennessee]

Could the magma reaching the surface possibly be the source of yuperlites or emberlites (the rocks that glow under uv light)? They're all along the shore of Lake Superior. I have heard the were brought south by glaciers from Canada. But this presentation sheds a new light on volcanics in the UP area. Thanks. Great presentation! Greg in TN

[@stevenbaumann8692]

We know where the source of the yooperlites are. It is Coldwell complex in Ontario. Which as you correctly pointed out are volcanic and plutonic igneous rocks. They are associated with and part of the Mid-continent rift, just like the basalts around Lake Superior. Their mineralogy is different. Unlike badly, granite, andesite, gabbro, and rhyolite, they don’t have quartz. They have foids. Quartz and foids cannot form together. The foids in the rocks many but sodalite just happens to have the intrinsic property of glowing bright orange.

[@timlester998]

You should do the Rio Grande Rift zone

[@charlesward8196]

Any chance of providing links to accessible published papers on this subject?

[@stevenbaumann8692]

I forgot if I included any at the end of the video. There are a lot of open source papers. Also, what we think we know is in the process of looking like it’s not really accurate.

[@roanmcmillan8863]

Hey! Loved the video, very informative and the graphics were awesome. Did you create the cross sections of the evolution of the rift or can I find them somewhere else? I would love to use them in my paper/presentation. Would cite the source of course:) Thank you!

[@stevenbaumann8692]

Roan McMillan yes. I made them. Feel free to screenshot them. Unless you want them another way. I could put them on the website.

[@roanmcmillan8863]

@@stevenbaumann8692 perfect screenshotting will work! Thanks a ton

[@stevenbaumann8692]

Roan McMillan you’re welcome! Feel free to do that on any of my videos.

[@lukemalm9190]

How does the volume of basalt/rhyolite compare to those seen in eastern Washington?

[@stevenbaumann8692]

That’s an excellent question! It’s far greater. The Pacific Northwest is a subduction area. This was a rift. The suspected largest single lava flow on the the planet is under Lake Superior. It’s informally just called the greenstone flow.

[@richardbailey5095]

@@stevenbaumann8692 Luke Malm may be referring to the Columbia River Basalt Group (CRBG) in Eastern Washington & Oregon. That seems to be a more complex story than just subduction and may involve the Yellowstone Hotspot, Farallon plate breakage, and the intersection of accreted terranes with the North American craton. Pulling from Kasbohm & Schoene (2018) "Rapid eruption of the Columbia River flood basalt and correlation with the mid-Miocene climate optimum" volume of the CRBG totals ~210,000 km3. Of interest, they suggest that 95% of erupted in about 600,000 years (16.7 - 15.9 Ma).

[@billheinowski1807]

I'm trying to come to grips with this in terms of super-continent cycles, getting date ranges all over the park! Near as I can determine, this would have occurred in Rodinia, perhaps near its break-up? I've seen some (only a few) that take Pangaea close to that far back, but most seem to agree that Pangaea was ~450Ma, a far cry for 1.1Ga...

[@stevenbaumann8692]

Bill Heinowski you are correct. Rodina is a bit of a mess. Although the mid continent rift failed in Lake Superior, it may have been successful elsewhere. We are trying to figure it out. Also. The Gardar rift in Greenland May be a key piece of the puzzle. We will be there in 2021.

[@billheinowski1807]

@@stevenbaumann8692 Sounds like an awesome trip - have fun!

[@robtayloe9352]

@@stevenbaumann8692 will be quite interested in seeing / reading / hearing more about this... thanks much

[@robtayloe9352]

Just found this awesome video by Steven Baumann, and from that have read this article as further food for thought: eos.org/features/new-insights-into-north-americas-midcontinent-rift . So forking bloody interesting, this entire madhouse of ancient geology science!

[@ffliberty]

Why did this rift not produce concentrations of gold like on the west coast? Or would it be plausible that it did and it's just too deep?

[@stevenbaumann8692]

We don’t know. It produced a lot of copper. I mean a lot. Boulders of pure copper waging nearly 2 dozen tons have been found. With minor silver. There likely isn’t any gold. The Archean rocks also contain copper, so that might have something to do with it. Rifts often don’t have any precious metals associated with them. As for the west cost, you’ve got a lot of different things going on, that may or may not have 1Ga analogs in the MCR. You have subduction and rifting going on (East pacific rise). Then there’s possible rifting happening in the basin and range further inland.

[@harrietharlow9929]

@@stevenbaumann8692 Didn't a lot of the gold and other precious metals tend to have resulted from hot water containing silicates and gold, depositing quartz in cracks, resulting in veins of metal?

[@harrietharlow9929]

I'm referring to the West Coast.

[@stevenbaumann8692]

Harriet Harlow yep. Many of the precious metals were injected through hydrothermal means, like you said. The copper is really abundant. Some of it could have been deposited directly as magma. As for why so much, we aren’t completely sure.

[@harrietharlow9929]

@@stevenbaumann8692 That's how much of the Troodos Complex copper on Crete was deposited. Much of the Troodos is one big ophiolite so seafloor, hydrothermal vents and all, ended up on land. Given that at one point there was a subduction just below where the Upper Peninsula now is, so I would think there may have been some ophiolite/hydrothermal vents involved in the origins of copper on the UP

[@chadjachowske1763]

Steve...do you know specifically where the magnetic high is located along the rift and the gravity high as well?

[@stevenbaumann8692]

Specifically no. I don’t think the USGS does either. If you did a search, you may be able to find the works. Michigan Tech might have stuff as well.

[@stevenbaumann8692]

Chad Jachowske try some of the references here. eos.org/features/new-insights-into-north-americas-midcontinent-rift

[@brianstevens3858]

? Still use ternary plotting for sed/metamor/igneous mix?

[@stevenbaumann8692]

Brian Stevens not sure what you mean by “mix”. Are you talking about migmatites? The diagrams are used for igneous rocks and sandstones. Then you have the USDA one for “soil”. They are the easiest to use in the field.

[@brianstevens3858]

I looked it up the system is basically the same although updates over the years have changed both it's form and accuracy."" csmgeo.csm.jmu.edu/geollab/Fichter/SedRx/Clastic.html "" This is what I was referencing although used to be much much simpler.

[@brianstevens3858]

To specify a "Rock" was devided by its components where one corner of the triangle represented it's sedimentary components etc. Often the % of others represented would be very very low, Metamorphics would be the hardest because the mass would have features from the intrusion represented by a variable amount and they could get quite hard to read, the newer methodology is much better. Trying to find an older reference to give clear example.

[@brianstevens3858]

This is the closest representation I have found and over time {40+ years it has changed from using the basics to a more specific {In that instead of a single rocks components and comparison of its individual specificity re. S/M/I now is more S/S/S type of thing} as near as I can find. Not good at explaining it.www.sepmstrata.org/page.aspx?pageid=608

[@stevenbaumann8692]

Brian Stevens you’re talking about the QFL diagram for sandstones. Yep we still use it. As a matter of fact in my Jacobsville paper (2016) I used it to delineate and correlate the Jacobsville with the Bayfield. Both units show an immature-mature-immature sequence. It was key to the correlation. Not so much with the Copper Harbor, since it is all lithic arenites. Grain size was more important for the Copper Harbor.

[@frankanddanasnyder3272]

2017...wow, 4 years out of date....cross section be at...? A A' or A B. Which is it...?

[@stevenbaumann8692]

If you had actually listened to me talking you would know I say A is the left B is to the right. I couldn’t put A’ in the video software I had at the time and I didn’t prep a slide for it. That’s why I explained it. So pull the wax out of your ears before you make ignorant comments. 4 years ago isn’t that long ago. Nothing has changed much. You don’t ask many questions in life do you? You’re the kind of person who thinks they know everything and view minor inconsistencies as massive shortcomings because you’re trying to hide your ignorance in smugness…aren’t you?

[@keithmillard2527]

@@stevenbaumann8692 AMEN! Thank you! Well put!

[@rikkispence7049]

I don’t think this rift is so “failed” and reactivating .. IMO

[@stevenbaumann8692]

It’s 1.1 billion years old and the continent is still intact. It did fail. Rifts form ocean basins, like the mid Atlantic ridge within 15-30 million years. Since it’s fail, there has been compression in the area reversing the old extending faults. Plus no modern earthquakes occur on it. It’s dead. There’s other failed rifts around North America. The Reelfoot in the continental US and the Gardar in Greenland.

[@LardGreystoke]

You're only a failure if you think you are. The rift was its own worst enemy.

[@rikkispence7049]

@@LardGreystoke bahaha Mary Greeley now doesn’t think it was a failure either .. 😁

[@lethargogpeterson4083]

At 5:35, don't the half arrows on the Y province indicate contraction, not extension, or am I missing something. Either way, thank you for an interesting video.

[@stevenbaumann8692]

You are absolutely correct. I got it backwards. Thank you!

[@harrietharlow9929]

Thank you for a very interesting video! You helped me to understand the rift much better.

[@stevenbaumann8692]

Thanks for watching.

[@markharder3676]

How did geologists characterize the deep strata like the core that don't outcrop on the surface? Can one use seismography to do this? If not, then how?

[@stevenbaumann8692]

Yes. That's exactly how. Also by using Aeromagnetic and gravity maps. It's really the only way to see that deep. And it's not perfect.

Loved your channel! I also try to talk about geosciences but in portuguese.

[@direbearcoat7551]

How does this rift square with Pangaea?

[@stevenbaumann8692]

This rift is 1.1 billion years old. Long before Pangea. It is somehow related to the Supercontinent Rodinia.

[@EricSilkowski]

Enjoyed the presentation. I did not know the MCR extended into north AL (according to your graphic) where I live. I think you meant to say that the "MCR extends all the way to AL and almost as far as MS" rather than vice versa :-)

[@stevenbaumann8692]

Thanks! It likely did extend to the end of the continent at the time.

[@smokingjoking]

W. N. W. of Iron mountain there is an area some kind of anomaly I don't know a lot about geology but it forms a ring of red color around iron. On some of the geology maps I have looked at. Do you know anything about this ring. Is it an old volcano or something? I have canoed thru this area and found some very interesting things.

[@stevenbaumann8692]

smokingjoking if you’re referring to the area between crystal falls and stambaugh I think that’s a basin structure. It’s all Paleoproterozoic rock there. It’s also near the Place where Wisconsin slammed into everything north of there during the Penokean Orogeny about 1.87 billion years ago. It’s way outside of the Midcontinent Rift (1.1 billion). The rock is much older. That being said, there is one known kimberlite at Lake Ellen NE of Crystal Falls. Other than that, I’m pretty sure the only actual known volcano is part of the Midcontinent Rift. It forms the Porcupine Mountains.