Rock and Roll: The New Madrid Fault System Part II: Some Geological History By Stephanie Osborn

Rock and Roll: The New Madrid Fault System Part II: Some Geological History By Stephanie Osborn

Rock and Roll: The New Madrid Fault System Part II: Some Geological History

Excerpted from Rock and Roll: The New Madrid Fault System, ©2017

By Stephanie Osborn

http://www.stephanie-osborn.com

Images in this article are public domain, unless otherwise specified.

 

This whole collection of writings started off with an email exchange, months ago. Our illustrious hostess was part of the discussion, and expressed interest in my converting the info to one or more blog articles. Then, when the LibertyCon programmers heard about it, they asked me to give a presentation on same, which I did.

The presentation was a full house, and at the end, there was a request for me to convert it to blogs and/or an ebook. I asked how many would like to see an ebook of the material; virtually every hand in the lecture hall went up.

A little over a month later, with additional research under my belt and factored into the manuscript, the book has gone live. And as promised, I am providing Sarah a series of blog articles on the subject. This series of blog articles is only a small fraction of the material contained in the ebook; it may be considered in the nature of a series of informative abstracts of the information contained therein. For additional information, may I recommend that you check out Rock and Roll: The New Madrid Fault System.

 

Part II: Some Geological History

As the conveyor belt of Earth’s mantle convection floats the crustal plates around, numerous supercontinents have been slammed together and ripped apart through the geological eras.

Some 1 to 1.3 billion years ago, around the beginning of the Neoproterozoic period or possibly a bit before, a supercontinent formed in Earth’s southern hemisphere. Today, geologists call it Rodinia. It is the very earliest supercontinent we can confirm. There were probably others, but we don’t have definitive evidence yet.

Roughly in the middle of Rodinia was a plate geologists called Laurentia. It was the ancient core that came to comprise what we now call North America.

north america

But about 750 million years ago, only ~250-500 million years after it formed, Rodinia began to rip apart. Why?

Because the presence of the big supercontinent insulated the layers below it. A hot spot developed in the mantle underneath, generating an upwelling in the plastic rocks of the mantle, and convection moving away from the hot spot. This produced an upward force under the continent, tending to crack it apart, and “conveyor belts” to carry the pieces away. This is believed to be why all supercontinents ultimately break up.

break up

Gradually Rodinia broke apart, and the new continents moved away from each other. The new continent of Laurentia was put under tremendous stress, as it was pulled from multiple directions—keep in mind, there was considerable friction to deal with. Faults behaved the same then as they do now, and they dragged and ripped at the plate that had been the heart of the supercontinent.

Multiple rifting areas have formed mid-continent due to supercontinent breakups over geologic history. Only one of these is the Reelfoot Rift, around which the New Madrid Seismic Zone and others formed. The Reelfoot Rift is a failed plate boundary; had it torn all the way through, there would be no North American continent as it currently exists.

The Reelfoot Rift has two principal seismic zones and quite a few secondary zones. The primaries are the New Madrid Seismic Zone and the Wabash Valley Seismic Zone.

Seismic zone

 

The New Madrid grabens

The main graben runs right down the Mississippi River central valley. The northeast end runs diagonally from roughly the Land Between the Lakes National Recreation Area to the Shawnee National Forest. The southwest end is somewhat uncertain, but has been identified at least as far as a Mariana-to-Searcy, AR line.

But…there’s more than one graben.

more than one grabben

[Map from Van Schmus, W. R., Bickford,  M. E., and Turek, A., 1996, Proterozoic geology of the east-central mid-continent basement; in, Basement and Basins of Eastern North America, B. A. van der Pluijm, and P. A. Catacosinos, eds.: Geological Society of America, Special Paper 308, p.7-32. Note the Southern Oklahoma Aulacogen, which extends through TX, OK, NM, CO & UT; it is also a failed rift produced at roughly the same time and for the same reason as the Reelfoot Rift, which houses the New Madrid fault system. Zoom view mine.]

 

In fact, there are at least four grabens, or fault-block valleys, but unlike most multiple-graben systems, they do NOT lie in parallel. Instead, they all radiate out from a central stress point. One of these grabens, the Southern Indiana, is contiguous with the separately-identified Wabash Valley Seismic Zone. Several others exist, including the Cottage Grove Fault Zone (CGFZ); the Rough Creek Fault Zone (RCFZ); the Ste. Genevieve Fault Zone (SGFZ); and the Shawneetown Fault Zone (STFZ).

States directly

States directly affected include:

  • Illinois,
  • Indiana,
  • Missouri,
  • Arkansas,
  • Kentucky,
  • Tennessee, and

States indirectly affected include:

  • Alabama,
  • Oklahoma,
  • Louisiana, and

The evidence for long-term quake activity along the New Madrid system is mixed. Tree ring growth depicts the 1811-12 quake series, but nothing prior to that, back to medieval times. Yet objects inadvertently buried in previous events—pottery, knapped blades, etc. distinctive to a given period—can be type- and/or carbon-dated, showing evidence of massive quakes in:

  • 1450AD,
  • ~900AD, and
  • ~300AD.

Other geological evidence indicates major quake swarms in:

  • 2350BC,
  • 3500BC, and

 

To obtain a copy of Rock and Roll: The New Madrid Fault System by Stephanie Osborn, go to:

https://www.amazon.com/dp/B074SJ8ZPT

73 responses to “Rock and Roll: The New Madrid Fault System Part II: Some Geological History By Stephanie Osborn

  1. been a long time since I rock and rolled.
    The move from Texas to Michigan took me from more frequent earthy quaking

  2. Forgive me in advance; I’m not quite awake and sort of free associating. Is New Madrid a sort of geologic fossil left over from a supercontinent, or is more recent?

  3. Yippee! Thank you, again.

  4. So New Madrid is due for another quake possibly in one hundred years or so. Maybe.

  5. BobtheRegisterredFool

    So there’s a known system in Oklahoma, and it may be about right for something to be kicking loose again there.

    • Said system runs through TX, OK, back through the TX panhandle, NM, CO, and possibly into eastern UT.

      It was created at the same time, and for the same reasons, that the Reelfoot Rift system was created.

      So…yes.

  6. The Oklahoma quake, not on a New-Madrid related system, shook my bed. I noticed the rolling motion and thought “Huh, earthquake.” Nothing fell off the shelves, but it was an interesting way to start a Saturday.

    I suspect a major New Madrid temblor might kick a few other faults, like the Humbolt up in KS-OK and some the OK-TX systems into grumbling for a while.

  7. was gonna ask a bunch of stuff about the Rodinia map but i’ll just go wikiwander

    • Well, I’m less knowledgeable about supercontinents as such; this was supposed to be about seismology, and it sorta got into supercontinents as the cause of the rift system. So yeah, a websearch is probably your better bet.

    • The one I was thinking about was Pangea, the last. The free association keyed on the Mississippi following the failed rift, and that reminded me how some rivers in Georgia make an abrupt turn east along the Brunswick Magnetic Anomaly, where it seems the North American Plate and the African Plate bumped. Anyway, Rodinia was two supercontinents earlier, which means that feature along the New Madrid is old.

      Guess what I’m wondering is how many ancient faults are undiscovered. sure, they look like they’re mid plate now but what were they millions of years ago? And could we detect them unless there was motion along them?

      Just free association.

      • Well, evidently for North America, midplate is and ever was. The craton that is the heart of the continent has been the heart of the plate through as many supercontinents as we’ve been able to trace and model.

        • The pieces that would form the Canadian Shield, the core of North America, mostly came together 2000 MY (million years) to 1800 MY ago. Presumably this was during assembly of an earlier supercontinent which later split up and reshuffled the pieces, but those particular pieces stayed together. The oldest parts, the Superior, Hearn, Slave, and Wyoming provinces, formed from rocks dating back to 2500 MY or earlier. The rocks between them are younger, but the basement rocks of Canadian North America have been together since before 1700 MY ago. The edge of the continent then would have run approximately from the (future) Northern Great Lakes region west to Wyoming.

          The “southern” boundary (in current coordinates, who knows which direction it faced back then), continued to grow as island arcs came in and crunched and stuck, the rocks getting younger toward the south. The basement rocks of the New Madrid area formed from these colliding arcs, sometime around 1500 MY to 1300 MY ago.

          • I guess what was in the back of my mind was whether old faults ever “heal.” A metalworker who knows what he’s doing can weld and anneal steel until it’s one piece, but various things can happen so that it’s a weld, but not a single piece of steel, and that can become a point of failure. How is it with rocks? Can they become one solid piece, or will those faults remain until the entire slab is subducted?

            Please note this does not have to do directly with New Madrid, but New Madrid makes me think of “quiet” areas not associated with quakes, until one hits. Never knew of the Charleston Quake until the Earthquake Bolts came up in a discussion of homes.

            • I’m not sure, but if rock is subjected to enough heat and pressure (metamorphism) that might do it. Most earthquakes occur in the upper crust where the temperature and pressure are low, and the rock is brittle enough to fault. By10 miles down rock will undergo plastic flow instead of cracking. Deeper earthquakes do occur, almost always associated with known subduction zones. There the descending oceanic crust had been chilled and may remain brittle to a greater depth before it heats up enough, But quakes deeper than that, dozens or hundreds of miles down, remain poorly understood.

              • About the only way to truly “heal” a fault is to recycle the plate it’s on. (AKA subduction and subsequent melting in the mantle.) Metamorphism at relatively shallow depth (such as is found in mountainbuilding) tends not to do it, else there would be no such thing as fault-block mountains; it’s simply shifting the chemical structure within the rock, allowing for recrystallization etc. But it doesn’t generally weld the two sides of the fault back together.

                • What she said.

                • And continental crust will fault under stress anyway. Old faults do get reactivated because they are pre-existing zones of weakness, but if a fault isn’t oriented in the right direction to move a new one gets created. Continental cratons are thicker and colder than active mountain belts, so the rock is stronger. The stress gets passed down to the next weak link, Mountain belts, still warm from formation, with recently active faults and perhaps tall enough to initiate gravitational collapse, tend to repeat as continental margins. The Basin and Range of the Western US used to have an Andes-style high mountain range before the Rockies rose, and that area is now collapsing and spreading without a subduction zone to support it. There are other factors too, including “flat subduction” which removed continental material and may have pushed it underneath the Rockies.

                  It takes a lot to tear a craton. A hotspot track like Yellowstone may do it, if it lasts long enough. But Yellowstone has only just begun working on the thick continental crust and it still has over two thousand miles to go It has been working its way through accreted terranes and a coastal batholith complex. Without a hotspot track or other pre-existing weak point continental breakup requires a very long period of tension, tens of millions of years. The Midcontinent Rift beneath the upper Midwest and the Great Lakes spread for 15 or 22 million years, but the forces creating it stopped when Rodinia was formed, blocking an escape route. The African rift valleys have been spreading, slowly, for some 20-25 million years, and still haven’t split East Africa the way the Red Sea and Gulf of Aden have carved off Arabia. It will take more millions of years, and if the forces causing the spreading wane it will be a failed rift.

                  There are many, many old faults due to billions of years of active tectonics. They can be found easily where plant cover and sediment is absent, but underneath soil and vegetation the evidence is hidden. River valleys are terrific hiding places, as are coastal plains. Everything is buried.

                  • All of this. Separating out the effects of the Midcontinent Rift from the Reelfoot Rift was an interesting task in itself. Half my websearches wanted to talk about the Midcontinent Rift, which is older, and not the Reelfoot Rift.

  8. This is believed to be why all supercontinents ultimately break up.

    I thought the basic reason for supercontinent breakups was the pressure of working through a relationship in the public eye.

  9. c4c

  10. Paul (Drak Bibliophile) Howard

    Grumble Grumble

    Stephanie is another of the “Evil Authors”.

    I just got through purchasing too many eBooks and this one was one of them. 😉

  11. Timely! All the local buzz tonight is “Did you feel the earthquake?” 5.3, between Soda Springs, Idaho, and Afton, Wyoming.

    No, I didn’t notice it. Some of my kids did, others didn’t. Looks like about 50 miles away, and seems to be a good excuse for everyone to start sharing Yellowstone Scare Stories again.

    • Well, but it’s not in anywhere like the right place to have anything to do with Yellowstone. It’s even well to the south of the ancient track of Yellowstone calderas, as the North American plate moved over the mantle plume hotspot.

      So if anybody says that, you can tell ’em it’s not in the right place. By about 200 miles.

      • Yellowstone’s behaving as nicely as usual. Some folks just like an excuse, and there’s always an “OMG The USGS reports 2000+ Quakes in the Last Month we’re all gonna DIE!!!” clickbait article somewhere out there. That being Yellowstone’s normal, and the USGS having equipment sensitive enough to pick the tiny quakes up. Other places have hurricanes and tornados, werewolves and serial killers: we have *cue ominous music* Yellowstone. (Though I’d love to see someone’s model of what the young uplift ranges out here are going to do when Yellowstone does go. I’m sure some bright young geologists have done it, and probably the models fall in fantasy rather than science fiction just from the complexity and the assumptions that would have to go in. Hmm . . . makes a note to look into it.)

        When Dad dug under his PhD Paleontology and pulled out his MA Geology it was sure nice to’ve just had a refresher in word definitions! Thanks!

        • I’m planning on writing an ebook on Yellowstone sometime in the relatively near future. One of the best suggestions I’ve seen for a title was “Kiss Your Ash Goodbye”…
          😀

  12. Where can I get a hard copy of this.?in Kindle books has been uniformly negative.

    • Sorry, should have read, “My experience with any visuals (photos, tables, illustrations, etc.) in ….”

      • The ebook only has a few illustrations in it, because most ebook purveyors take an extra (substantial) cut out of the royalties for each download of an ebook surpassing a certain file size. I added more illustrations to the blog articles, even though they contain only part of the info in the book.

        • Copy that. Live on the Rio Grande Rift and we occasionally get a tremor, but no big ones recently (geologically). There are dire predictions, however.

    • I’m afraid it’s not available in print because it’s too short to be a print book.

      I do plan on collecting my popular science ebooks into a single volume in the not-too-distant future, and making the collection available in print.

  13. Mrs Hoyt, I commend you for having a blog with such gneiss topics and discussion.