Ruminerian X – Rio Grande Rift

From Wikipedia: “A lineament is a linear feature in a landscape which is an expression of an underlying geological structure such as a fault. Typically a lineament will comprise a fault-aligned valley, a series of fault or fold-aligned hills, a straight coastline or indeed a combination of these features. Fracture zones, shear zones and igneous intrusions such as dykes can also give rise to lineaments.”

I first ran across the term while reading about the New Madrid Seismic Zone. Specifically, the Commerce Lineament, and the Bootheel Lineament. The Commerce Lineament corresponds to the Commerce fault and is in fact, a defacto boundary fault for the Reelfoot Rift. An oddity of it, is that if you extend a line along it’s path to the south, it points right across the planar alignment of quakes that occurred near Guy Arkansas in the last couple of years. That planar alignment of quakes is aligned at approximately 16°, but the faults in the Thebes Gap area tend to be just short of 30° alignment.  Connect? Beats me, it could just be an odd coincidence. That ancient mega quakes have occurred outside of the NMSZ is evidence by the sand blow fields that have been explored to the east of there along the floodplain of the Mississippi. But, this isn’t about the NMSZ, so I will leave one of my favorite topics behind.

A long time ago, on the western extent of the North America continent, there was a subduction zone.   The other plate involved in this collision was the now extinct Farallon plate.   The remnants of that plate are the plate shards off of the Oregon and Washington state coasts, Juan de Fuca, Explorer, and Gorda plates. To the south, the Rivera plate fragment and the Cocos plates still exist. Along the western boundary of the Farallon was a spreading center. Part of that spreading center still exists in the form of the East Pacific Rise and the Juan de Fuca ridge.   Located along the Juan de Fuca rise are Cobb Seamount and the Axial Seamount. Both are underwater volcanoes. Both are fed by magma genesis along the ridge, and by the Cobb Hotspot.   Yes, you read that right, the same general set-up that feeds Bardarbunga. If you roll back the clock several million years, you have essentially the same geologic set-up that eventually gave birth to Iceland.   Where it gets really interesting is when you concider what happened to the subduction zone once the ridge itself was driven under the overlying continental crust.   Global Tectonics, 3rd Ed has this to say: “A quadruple junction existed momentarily at about 28 Ma, but this devolved immediately into two triple junctions”. Since these two semi-stable triple junctions only have certain geometries that are stable, the two junctions migrated north and south along the continental crust boundary until they reach a stable geometry. The resulting sites are the Mendocino triple junction and the Rivera triple junction. What was left behind after they migrated is the San Andreas Fault system. As the now subducted spreading ridge passed under the South Western US, it’s high magma production rate initiated crust thinning and the formation of the Basin and Range province.   Much of it’s geology is made up of Horst-Graben structures, with many showing up at half Grabens. Poking around in Wikipedia, I get the impression that the brunt of the ancient Farallon plate now lies under the Eastern Seaboard of the US. If this is so, it is likely that what once was the spreading center now lies under Western Texas.   I say this because this is the location of the ongoing rift valley formation known as the Rio Grande Rift. It is made up of a chain of basin structures stretching up from Mexico into Colorado.   Now, I have no proof that that old spreading center is located there, but the general layout of the suspected remnants of the Farallon point towards that being a pretty good explanation. South of the Basin and Range, is the Sonora Megashear in Northern Mexico. South of the Megashear, the suducting Cocos plate (also a remnant of the Farallon) is undergoing something approximating “flat slab” subduction. This means that it is slipping under at less than 30° dip. This puts Popocapetal far inland near Mexico City. To the east of here, the Cocos plate abruptly stops. A section of what appears to have been part of the Cocos seems to have been detatched and sits at a much steeper angle, plunging down into the Mantle. Initially, it was thought that this was an example of slab rollback and detatchment, but further examination shows that there is another subducted plate segment that seems to have pinched and cut off the now detatched segment of the Cocos. One idea for the owner of that subducted “other” plate section, is the Yucatan block as it moved away from Texas and rotated into its current position. See “Mexico Subduction Experiments” for further info. The only real reason that I bring this up is that it is pretty likely that the Farallon plate north of the Sonora Megashear had a similar shallow angle as it went by. The only real indicator for something different is the existence of the Megashear itself, acting as some sort of boundary marker. This could also be what the Olympic-Wallowa Lineament is up in the Pacific Northwest. It is aligned with the boundary for the Juan de Fuca dn Explorer microplates. Of course, to add to the confusing mix, it’s also aligned with the track of the supposed Newberry Hotspot. And now, for the insane bit. The track of Newberry Hotspot does not correlate with the motion of the North American Plate, like Yellowstone does.   Another supposed hotspot is the Raton Hotspot, blamed by some for the Jemez Lineament. The Jemez Lineament correlates to a series of volcanic centers stretching from San Carlos volcanic field through Jemez Mountains.

compositeOne website has even stated that the track of the Raton Hotspot is a better record of the North American plate motion than Yellowstone. The strange part is that if they are correct, then the Raton Hotspot should be under the border of Oklahoma and Colorado. I tried tracking down their source material but ran into a paywall. As for the volcanic fields along that region, you can’t rule out that they were caused by eddy currents and turbulence in the athenosphere as the trailing edge of the Farallon went by.   In Colorado, there have been a series of earthquakes over the last few years. Despite the alarmism of many people (with vested interests), these seem to be along the eastern boundary of the northern extent of the still forming Rio Grande Rift. In a few million years, when this rift meets the southern end of the ultra ancient Mid Continental Rift, (actually located over in Kansas, bounded on the east by the Nemaha Ridge.) it may or may not reactivate it. Since it tracks down the middle of Lake Superior, it is in a prime position to eventually break up the North American Craton.   I won’t be around to see that happens, but the much younger (though still ancient) Reelfoot rift is still making noises over near Tennesee. Speaking of which, while rummaging around for data for this post, I kept getting distracted by info on the Reelfoot rift. At a passing glance, I notices one gob of tex that noted that two sediment beds separated by several thousand years of when they were emplace, were lying within a few inches of each other. That un-nerved me. To do something like that, you literally have to take the sediment beds and throw them up into the air and shake them around. The only time you get that much energy is in MMI XII shaking.   You don’t start getting that level of violence until you go above Magnitude 8.2 in earthquake strength.   That is where stuff is literally thrown up into the air. We’re talking 770% g acceleration. This was in the vicinity of Thebes Gap along the Mississippi River and was in an article discussing when the Mississippi switched from flowing down the western side of Crowley’s Ridge, to the East where it currently is.

Pilger makes a pretty extensive exploration of various reference frame ideas in “The Bend: Origin and significance” )

Some insightful commentary about the Thebes Gap.:

Harroson and Schultz: Strike-Slip Faulting at Thebes Gap, TectonicsVolume 13, Issue 2, Article first published online: 26 JUL 2010.

http://onlinelibrary.wiley.com/doi/10.1029/93TC03190/pdf

And an awesome reference:

Global Tectonics, 3rd Edition
Philip Kearey, Keith A. Klepeis, Frederick J. Vine
January 2009, ©2009, Wiley-Blackwell

This is the “go to” book when it comes to things tectonic.

Advertisements

69 thoughts on “Ruminerian X – Rio Grande Rift

  1. I hope ‘yall enjoy the read. It’s a bit sparse on imagery and long on text.

    The basins that make up the rift are from Wikimedia and overlaid on a Google Earth representation of the area. The quakes are from the USGS (which is why their logo shows up on it).

    Some of the volcanic centers that make up the Jemez Lineament (and supposed Raton Hotspot track) are shown in the overlay as well.

    The author of the Plate Frames site has graphical representations of the track, shown in relation to the Yellostone hotspot track. I reccomend that you check it out if it interests you. But, that’s his imagery and I will not lift the images since I can’t even locate his reference documents. (paywalled).

    As for the odd stone that my Stepson located. I cannot vouch for the location. This means that it could have been brought in from elsewhere and not be native to where it was found. However, the fact that it was granite did lead me on a nice document chase that turned up a good paper on the Northern Franklin Mountains. Yes, there were granite intrusions into the area, but that doesn’t mean that I have a sample of them. It could just be road fill.

    http://pubs.usgs.gov/bul/1298/report.pdf

  2. Thanks Lurking. Another geological mix and match. It’s rather like the African rift but a lot older.

  3. Thank you, Geo Lurking. An interesting area. It is going to take a few reads to get my head round the various plates, cratons, rifts and hotspots 🙂

    Intriguing that the Newberry hot spot track does not follow that of the North American plate, whereas the Yellowstone hot spot does.

  4. Cool and very intense article GL. Makes for fascinating reading. I kind of had the assumption most of the US is tectonically dead, apart form the obvious parts. You’ve woken up my interest in what is going on there! Thank you – much appreciated!

      • The graphic in the Wiki link for the current location of the Farallon plate is difficult to grasp as it is, and the best imagery set for the slab roll-back under popo is at the MASE link. I didn’t wish to pilfer anyones imagery, so I did the next best thing and pointed at the site that had them. This way you can read the descriptions of what the images represent, rather than having me try to replicate their work.

        USGS and other researchers are doing a high resolution seismic survey of the US and have only recently moved the stations to the mid continent of the US. In a few years, I imagine several papers will be produced that yield a clearer picture of what the structure of the crust is like. The cool bit is that the NMSZ and Rio Grande Rift are both within the regions they either have done, or are currently doing.

  5. Just saw this article and though of… well, quite a few people who hang out here… ‘Friends Of Lava’ indeed! http://www.bbc.co.uk/news/blogs-news-from-elsewhere-31987941 …”A long-running dispute in Iceland about a new road blocked by a large rock some consider to be an “elf church” has finally been put to rest – by moving the offending 70-tonne mass.

    A large crane was used to relocate the outcrop in two pieces – the larger one weighing 50t – closer to similar “elf-dwellings”, the Morgunbladid daily reports. Work on the highway project on the Alftanes peninsula, near Reykjavik, was halted by Iceland’s Supreme Court in 2013 after campaigners said it would disturb a protected area of untouched lava and culturally important “elf habitat”. According to the Friends of Lava group, this included the 12-foot-long jagged rock considered to be the legendary Ofeigskirkja – a church or chapel used by the Huldufolk (“hidden folk”), derived from the elves of pagan Norse myth.

    The deadlock was broken through the mediation of a local woman and self-declared seer, Ragnhildur Jonsdottir, who called for a “pact between elves and men”. “The rock will be moved next to other beautiful and similar rock formations, thus creating a unified whole,” Iceland’s roads commission said in a press release announcing the work, which was carried out on Wednesday. Commenting to Morgunbladid, Ms Jonsdottir said the elves had one and half years to prepare for their church’s transfer, and would be happy in their new surroundings.”

      • The error ellipse is just that – an area of uncertainty. The arrow could point at any location within the ellipse, within the accuracy of the data. If the origin is within the error ellipse (as is the case here), chances are that in reality there was no movement.

  6. It really has me thinking that the North American plates are more active than many even know about. These earthquakes that north Texas and up into Oklahoma have me thinking that much of the occurances are geological.

  7. Enjoyed the post Geo. While reading it, I went to the Wikipedia reference on the Midcontinent Rift System in your article. The part that says ‘The rift today’ has an image of Lake Superior. It shows the movement of the faults under the lake. My curiosity is how this will change the lake in the future. Of course, years it would take but still I find this interesting. Thanks. 🙂

  8. The Rio Grande valley is fascinating to drive through. There is evidence for past volcanism everywhere you look – all small scale, but it still makes you wonder what is next! The activity seems to be mainly outside of the valley, perhaps because rising magma can’t aim that well. And I did wonder whether it was really wise to pick this area to test the first nuclear weapons! The valley of fires is well worth a visit. Nothing imminent, but for instance sits spot on the largest (or was that second largest?) inflating magma chamber in the US. It is rising by 2mm per year. Now we could assume that caldera formation requires say a preceding rise of 100 m , after which withdrawal/eruption of the magma causes the collapse. (Since Bardarbunga we know that the magma may escape a long way away, not necessarily above the chamber!) That puts the time scale for caldera formation in the area at 50,000 yr. I guess that is why new Mexicans are so relaxed.

    I can’t find any evidence that the Raton field is a stationary hotspot. It is not enough to have a line, you also need an age gradient. In this case Valles caldera, at he other end of the line, is still active. It may be hot, but it isn’t a spot.. more like a hotline..

    Looking at the global maps of proposed hotspots, a quarter of them lie on mid-oceanic spreading ridges. If hot spots are independent features, you would expect only 1 or 2 to accidentally fall there. And none of those on the ridges show the kind of linear features with progressive ages – not even Iceland. It seems to me that the number of true, deep hotspots is rather less than claimed.

    • And my drive through there was at a time that I was desperately trying to get my wife home to see her dad before he passed away. The only thing that really was on my mind was making sure I had enough gas to make the next town. Getting passed by a tractor trailer rig doing about 100 mph was un-nerving to say the least. Did the trip non-stop, though I did have a few minutes of sleep while my wife drove for a bit… until I was woken up by the agents at an “agricultural inspection station” to see if I were in possession of some sort of dangerous fruit.

      • When I went to see the Valley of Fires, I was overtaken on the road towards it: a bendy and undulating road. Ten minutes later I saw that car again. Upside down some distance from the road. None of the five people in the car survived. The sight still haunts me. The road has been relaid since and is much saver. If only that had been done before that day.

      • Quite some time back, I did a stint as a volunteer firefighter, completing all my first responder classes and becoming state certified as a structural firefighter. A lot of what they taught went against my trainings as a shipboard firefighter, but given what I typically was responding to, was fully appropriate. However, I did have my share of responses to vehicle accidents and eventually, I had to give up the activity when I transfered to other duty stations. After I retired from Naval service, I moved back here where I had spent most of my on-shore duty assignments. There are still intersections and locations around here that give me cold chills down my spine from some of the stuff that had seen at those locations… usually horrific. The stuff of nightmares. And usually caused by some nitwit that ignored a sign and killed someone or that was out showing off and achieved the same result. Assisting EMS in removing teeth from a telephone pole will definitely stick with you… and put the concept of kinetic energy as related to motorcycles in a whole new light.

        The scariest accident that we rolled up on, had no casualties other than a few bruises for the truck driver. It was on a section of interstate and there were 15 to 20 cars literally scattered all down the roadway. Turned out they were scrap metal cars and the rig hauling them had overturned. Most of the units that were boxed into the call were turned back when it was found out that no one had been driving the cars.

        • To this day, my ears perk up when I hear a 640 hz tone. That was one of the frequencies that was used to activate the pager (Minitor) for my station.

          This is a conditioned response. Usually I got an adrenaline rush as the reward for hearing it, so I have a pretty good idea of what Pavlov’s dogs went through.

    • As for the magma being able to escape many miles away… I think Novarupta is one of the more spectacular examples of that. Following the 1912 eruption, the summit of Katmai collapsed forming a crater lake. Though it is possible that Katmai was just a resurgent feature of the greater Novarupta complex.

  9. new activity everywhere in Vatnajokull as has been said that Badarbunga would wake up many other volcanoes by the scientists.

    • Like most media pieces, it’s canted heavily on the “wow” and is quite sparse on actual facts.

      THe geologic scenario is going to be similar to the Indonesian mudvolcano. It is also pressurized by being under a graben. With the Indonesian mudvolcano, it was strong enough to blow-out the well casing, making getting it under control nigh impossible.

    • I’ve mentioned before that I did some time as a structural firefighter. In part of my training, I had to learn about the operation of the pump on the apparatus. (aka “Firetruck”). Typically, the second in truck to an incident, would tag a hydrant and lay in a 5″ supply line so that we could continue fighting the fire uninterrupted. Many departments operate this way. One reason that we were never fond of taking over a fire after the City fire department is that they use twin 2 1/2 inch lines for their supply lines, and we were configured for a single 5 inch line. The downside of using the twin lines is that you have twice the amount of labor to lay out and pick up the lines, and you only get a doubling of the water flow. With a single 5 inch, you get 4 times the water flow. And when it come to overpowering a fire, the rate that you put water on it really determines how effective you will be. The same thing applies to VEI. An eruption can progress along with a moderate plume for a year or so, and come out as VEI 5. A single blast can loft material at an obscene rate, but not climb above VEI 4 if it only lasts a short time. VEI is based off of total volume of ejecta. Huluhraun is already up into the VEI 5 range, but has been nowhere near as energetic as Puyehue-Cordón Caulle. Reportedly, the eruptive plume for Puyehue-Cordón Caulle was over 5 km wide.

      • Can you imagine standing there and watching that? Good pictures capturing the lightning too. I got my husband to come and watch. I’m hoping little by little I’ll get him hooked too. 😈

    • They had used a 3D printer on his skeleton and found his disfigurement of his spine was from scoliosis. It was obvious looking at it. As far as the DNA not surprising. 🙂 Thanks for the article.

    • Teaser!!

      (Doesn’t matter, I was also teasing with my 19:57 comment 😀 )

      For those that haven’t picked up on it, KarenZ has authored our next article. 🙂

  10. Hello,
    There appears to be a lot of venting going on around the Holurhaun craters this afternoon/evening. Screen grab taken from the Mila Bardabunga 2 cam around 18:05z

    It would be good if the MogT cams on the west side of the crater could be restarted, as they are the closest and could make it easier to assess what is going on

  11. Hi all! Do we have someone ornithologically inclined here? I just captured these birds on the three Shiveluch webcams, it would be interesting to know what they are. Perhaps one can tell from their appearance of flight? Click on the image for large view.

    • Hi Granyia.
      I could hazard an informed guess here. There are two Eagles (No idea what variety). Certainly the far right photo is an eagle, looking at the size, arrangement of wing feathers and general profile. There are two smaller birds possibly large crows, again from profile and wing shape in flight.
      Another guess is that the two “crows” are mobbing an eagle pair. Bearing in mind that birds tend to start mating and pairing and seeking nesting sites quite early in spring/end of winter, quite a few weeks before actual egg laying. So possibly the two smaller birds are protecting their chosen breeding territory from potential dangers. A super interesting capture on a web cam 🙂

  12. The year 1816 is known as the Year Without a Summer (also the Poverty Year, the Summer that Never Was, Year There Was No Summer, and Eighteen Hundred and Froze to Death),

    Other large volcanic eruptions (with VEIs at least 4) around this time were:

    1812, La Soufrière on Saint Vincent in the Caribbean
    1812, Awu in the Sangihe Islands, Indonesia
    1813, Suwanosejima in the Ryukyu Islands, Japan
    1814, Mayon in the Philippines

    And in April 1815… Mount Tambora eruption VEI 7. (New Post, courtesy of KarenZ!)

  13. Is there a link to the OWL Paper? There is also a fairly substantial parallel structure in the Eugene – Denio Lineament as well. Lucky me, I live in the midst of these… Oregon really is a volcanic playground.

  14. The Columbia River Flood Basalts are definitely an acquired appreciation. To cross them is dreadfully boring. I am always in awe of how little and how much they have been distorted by time.

    Thank you for the article.

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s