Saturday, June 13, 2009

Time Warp: The Future of Western North America

There are so many times and places I'd like to visit in our planet's history... to see the sights, smell the odors, hear the cries and calls of the wildlife and taste the local produce. I mentioned a few in the original call for submissions, so I'll dispense with enumerating others. But suffice it to say, I (and others, I imagine) found it more dificult than I originally guessed to pick just one destination.

My final answer: I want to see what's going to happen with Basin and Range in western North America. Will North America remain a single block as Basin and Range spreading subsides? Will a single subcontinent break off and beome a Texas- or Alaska-sized island heading off to the northwest? Or will this region, composed of numerous terranes stitched together over the last 70-80 million years, break up and form a new generation of lithospheric ships, drifting independently on a Mohorovičić sea?

To put the question in context, we need to go back a few tens of millions of years, and watch the Farallon plate get consumed by subduction under the edge of North America. Between about 60 and 80 Ma, numerous small pieces of continental and thickened oceanic crust carried by the Farallon- terranes- were accreted to North America. Much of Nevada and Washington, and most of California and Oregon are formed of these terranes. According to Wikipedia,
"The Farallon Plate is also responsible for transporting old island arcs and various fragments of continental crustal material rifted off from other distant plates and accreting them to the North American Plate. These fragments from elsewhere are called terranes (sometimes, "exotic" terranes). Much of western North America is composed of these accreted terranes."
At 30 Ma, the spreading ridge (a remnant of which is now known as the Juan de Fuca Ridge) on the western margin of the Farallon had moved under the edge of North America, leading to the birth of the San Andreas Fault.
(This and the next illustrations from here) So one question I want to answer is "Did the subducted spreading ridge continue generating magma and spreading under the continent, or did it become inactive? Was it effectively destroyed, or is it still down there?" The current configuration is below:
There's very little doubt that much of the Farallon is still down there, the ghost of a deceased seafloor haunting the middle mantle. Tough Cookie at Magma Cum Laude has a good write-up that covers much more on this plate. Below is a representation of the current disposition of the plate from Wikipedia.
And below is another from The Art of Science- nice descripition of the photo here.
There are two competing theories (that I know of) to explain Basin and range spreading. First, the spreading ridge is still down there. In that case, the western US is in the process of giving birth to a new ocean. This is the story line so delightfully developed in John McPhee's "Basin and Range." The second theory is the subduction of the spreading ridge, which I can only imagine would be like me trying to swallow a watermelon without chewing, buttressed and compressed western North America, and caused an over thickening of the crust. In this narrative, basin and range spreading is simply a relaxation, a temporary expansion, following the removal of a previously compressive regime. This was the story line preferred by my profs 20+ years ago.

I haven't kept up with the literature. I don't know what directions ideas have gone in the last two decades. I just want to go see.

Here is an outline map of modern seismicity in the central and southern basin and range (from USGS). I have seen what look to me like fairly modern fault scarps on the east side of Steens Mountain in SE Oregon. There are some clear patterns, but I'm not sure what they tell us. Do we have enough of a record to say anything sensible? I doubt it.
Here's a Google Earth Image of the basin and range as it looks today:
And here's a map and list of major structural features associated with basin and range (hand drawn from memory, so do not cite this):
(note major features in bold yellow; approximate boundary of BR not associated with any features I know of in light yellow) From roughly north to south,

OWL=Olympic Wallowa Lineament, it's not clear what the significance of this feature is, but it may represent a more northerly analogue of the Brothers Fault Zone (BFZ)

YHS=Yellowstone Hotspot- I've always been tempted to link BR spreading to YHS migration, but I have nothing but intuition to back me up.

BFZ= Brothers Fault Zone- The roughly east-west trending northern termination of Basin and Range spreading across central oregon. The fault system allows accomodation between motion in BR and the (more or less) stable Blue Mountains of NE Oregon. More here.

WF= Wasatch Fault- The eastern boundary of basin and range in Utah.

EC-WRL= Eastern California- Walker Rim Lineament- The fault running through Owens Valley, up toward Reno, creating the eastern edge of the Sierra Nevada, and the apparent half-graben bounding the east side of the southern Oregon Cascades. I'm not finding documentation, but I drew this as a continuous feature; it may not be. I'll try to find more info later. But is this the actual western boundary of the North American plate?

SAF= San Andreas Fault- currently considered the western boundary of southern North America... but is it, really?

GF- Garlock Fault- A left-lateral strike slip fault in southern California, that, like the BFZ in Oregon, allows accomodation of basin and range spreading against non-spreading adjacent rocks.

Now the standard geo-future projection with LA near the lattitude of San Francisco, and seaboard southern California has become so iconic, I won't bother to reproduce it. But if, as I suggested above, the "EC-WRL" is actually the tectonic edge of the North America, and if the subducted ridge is still trying to spread, we might see something like this in about 30-40 million years:
But there's another possibility: might the Wasatch front be the edge of the future ocean?
And one final possibility that was the preferred hypothesis of a geologist from southern California whose lecture I attended a few years ago... I really like this one myself, but I don't have the background to judge how plausible it really is.
From Terranes was my home assembled. To terranes will my home return? Note that I have used major structures as the edges, but internal disruption is entirely arbitrary.

OK, enough chitter chatter! Let's Warp!

Friday, June 12, 2009

Friday Fragment: Blueschist

Today's fragment is one of my all time favorites, blueschist. This rock type is pretty easily recognizable, strangely enough, by it's blue color and schisty texture. The main mineral responsible for the blue color is glaucophane. Glaucophane forms at very high pressures, an equivalent of a minimum of 15-18 km (about 10 miles or more), yet relatively low temperatures of 200 to 500 Celsius. At those depths, the temperature should be much higher. So what kind of environment could have created this beastie?

It turns out this is a rock we couldn't have explained before the advent of plate tectonics. When cold oceanic crust subducts below the edge of a neighboring plate, there is some lag time before it can heat up to the ambient temperature of the depths it now occupies. Furthermore, since subduction consists basically of wedging surface material down into the earth, material along the upper surface of the subducting plate can be carried to great depths, detach, and be wedged back up toward the surface. In other words, material can be carried down to substantial depths (and the associated pressures), then fairly rapidly- in geologic terms- get shoved back toward the earth's surface, before it has time to heat up.

Of course, that's a pretty uncommon set of events. In consequence, blueschist is a pretty uncommon rock.

The first two pictures are looking parallel to the foliation. You can think of it as looking at a book edge-on; it's the view that shows the structure best.
Click for bigger.
Click for bigger. And the third is looking perpendicular to the foliation- again, you can think of this as looking at the cover, or open page, of a book. You can't see the internal structure and contortions this material went through during metamorphosis as clearly, but (if you look at the full size picture) you can see the felty texture formed when a foliated metamorphic rock is dominated by acicular (needle-like) mineral grains. The term for this texture that I vaguely remembered was nematoblastic, but like so much I have learned, this term is now obsolete. Another rock type that I associate with this felty texture is amphibolite, a product of fairly high-grade metamorphism of basalt. (Followup: this surface is dominated by what is probably a mixture of chlorite and muscovite- not acicular minerals- but the felty texture that dominates the rock shows through pretty well, I think)
This rock is a boulder that sits at the southeast corner of Wilkinson Hall, the geosciences building here at OSU. I'm not certain of its source, but I'd be willing to bet it's from Bandon, Oregon.
(full-sized GE image)
There is a large pod of blueschist along the terrace just inland from southern shore of the Coquille River, and this rock was quarried to build the south jetty. If you're ever driving through, it's about a mile off Route 101, and very much worth the time it takes, to go look at the jetty. The quarry is somewhat overgrown, but collecting should be done in that area, not on the jetty itself.

One last thing: those of you who have had the oppportunity and pleasure of studying thin sections know how stunningly beautiful even mundane rocks can become under a petrographic microscope. Those who haven't, well, take a look at some of these pictures. There are quite a number of pleochroic minerals, those that change color depending on the angle and polarization of light passing through them, but there are very few as stunning as glaucophane. I think these photos are copyright, so I'm just posting the link. If gemstones looked as nice macroscopically as many minerals do microscopically, no one would have ever heard of diamonds.

Final Destination?

Eerie... The Times (UK) is reporting that a woman who missed Flight 447 was killed when the car in which she and her husband were driving veered into an oncoming truck. The husband was badly injured. But next week a piano will fall on him.

Thursday, June 11, 2009

BBC: "Swedish pirates capture EU seat."

I meant to post this yesterday, then forgot. But it's too good to allow it to simply fade away:
The group - which campaigned on reformation of copyright and patent law - secured 7.1% of the Swedish vote. The result puts the Pirate Party in fifth place, behind the Social Democrats, Greens, Liberals and the Moderate Party.
So with the Pirate Party gaining political power, I may have to rethink my attitude toward the Rapture and the Apocalypse. Can the Flying Spaghetti Monster (may you be touched by His Noodley Appendage) be far off?

I Don't Buy It

I think they'd pull a corbomite maneuver. Though I doubt they'd end up drinking tranya with Darth Vader afterwards.

Wednesday, June 10, 2009

Wednesday Words

Oops! Forgot to post this feature last week! Oh well, it's Wednesday again, so here's the next five would-be words. Answers to the last edition can be seen in the comments here... we had some good ones.

C'mon, Let the Cat In, Already

Cute, but that growley voice in the background gets on my nerves. At my grandmother's house, the kitchen door had a hook, meant to keep the door open, near its base on the outside. I remember at least two cats that independently figured out that flipping that hook- basically using it as a door knocker- would get the hoomins to open the door and let them in. Ozma pushes the door, making it creak, and scratches. Dogs often figure out similar signals to be let in (or fed, or something else they want). Animals aren't dummies.

Tuesday, June 9, 2009

Yay! Another WIN For the Free Market!

See, there's no point in regulations (or enforcement) in a free market, capitalist economy. Corporations want to do right and serve their customers, and they know it's not in their best interests to, let's say, just as an off-hand example, manufacture products intended to sanitize skin and wounds in conditions so unclean that users of their products could contract serious, life-threatening infections from the products themselves. No Siree! That'd never happen if goddamn big government would just keep its meddling nose out of everybody else's business.
Some of Clarcon's products are marketed as antimicrobial agents to treat open wounds, damaged skin and to protect against various infectious disease. The FDA said its inspection revealed that the Clarcon facility in Roy, Utah revealed violations of manufacturing practices, including contamination of products and a lack of a sterilization plan or recall process.

Sea Life in Spaaaaaaace!

Yesterday, Phil Plait over at Bad Astronomy found this Tres Cool picture of Penguins swimming up from Mars:
Then OregonLive found this mesmerizing photo of a beluga baby and its mama navigating a reflection nebula.
So I had to to go and see if I could find at least one more example. Look! It's an ammonite! And we thought they were extinct!

Gorbachev Writes; We Should Read.

My friend Matt here at my favorite coffee shop just pointed out an editorial piece in today's Gazette-Times. In an ad deal, The Interzone gets maybe fifteen copies each day for the customers to read with their coffee. I am not a fan of the paper (understatement alert), and most days don't bother picking it up. So I would have missed this if Matt hadn't pointed it out, and I want to extend my thanks to him.

Mikhail Gorbachev wrote in the Washington Post Sunday (uncluttered printable version here, original online article here):
Years ago, as the Cold War was coming to an end, I said to my fellow leaders around the globe: The world is on the cusp of great events, and in the face of new challenges all of us will have to change, you as well as we. For the most part, the reaction was polite but skeptical silence.
Our perestroika signaled the need for change in the Soviet Union, but it was not meant to suggest a capitulation to the U.S. model. Today, the need for a more far-reaching perestroika -- one for America and the world -- has become clearer than ever.

But then came the economic crisis of 2008 and 2009, and it became clear that the new Western model was an illusion that benefited chiefly the very rich. Statistics show that the poor and the middle class saw little or no benefit from the economic growth of the past decades.

The current global crisis demonstrates that the leaders of major powers, particularly the United States, had missed the signals that called for a perestroika. The result is a crisis that is not just financial and economic. It is political, too.

The model that emerged during the final decades of the 20th century has turned out to be unsustainable. It was based on a drive for super-profits and hyper-consumption for a few, on unrestrained exploitation of resources and on social and environmental irresponsibility.

I think this is an important piece that everyone should read. Gorbachev tries to make clear that he is not calling for the US to follow a Russian model, but one that is uniquely our own. He points out that our current models- economic, social, political- are not getting people to the place they want to be. If our goal is to create enormously wealthy corporations and individuals, we've been successful beyond measure. If our goal is to create an environment where people can strive for happiness, security, and a modicum of assurance their children will have a shot at the same- and their children's children, and their children, too- what we have created is a dismal failure.

Hear, hear, Mr Gorbachev. Now if we can get some so-called "leaders" in this country to listen and develop your ideas, I'll be much less pessimistic regarding the future of my species.

Monday, June 8, 2009

Funniest First Line for a Science Blog Ever

From Jeff Masters' WunderBlog:

"A proven way to reduce the incidence of dangerous weather phenomena is to schedule a multi-million dollar field experiment to study the phenomena."

Interesting post about Vortex2 tornado study, which up to this point has not had many tornadoes to study. Some very impressive Doppler Radar Images.

Surveillance Society

Today is the 60th anniversary of the publication of George Orwell's classic, 1984. In one of those synchronicities I love, I posted a comic referring to the concept in the title in my last post from yesterday. Britain has gone much further than the US with respect to monitoring private communications (e.g. phones and e-mail), and public movement, but we mustn't delude ourselves into thinking we are fully aware of the degree to which our own governments are monitoring our communications, our actions, our purchases, our readings, and our movements- or even what aspects of our lives they are capable of monitoring. My skepticism monitor jumps to eleven any time I hear the "slippery slope" argument, but the fact that the idea has been so over- and mis- used does not mean that it's always invalid. This might be a good idea to ponder on today.

And if you haven't read 1984, you should. I could only read it once. I tried to read it again during shrub's second campaign, and simply couldn't: it was that raw and depressing.

Sunday, June 7, 2009

Sunday Funnies

They're down there somewhere...(From ...if you get your eyes open wide enough to find them. They'll hit you in the face like a wall.

Oh look! There's one! "Where's Waldo?" for beginners:
(From Picture is Unrelated) And for those whose Waldo-seeking skills are a little better developed, there's another one over at Abstruse Goose. However, if your eyes are as bleary as this poor fellow's, you may have a hard time with either of those 1- and 2-star puzzles.
I got several positive responses from last week's "Checker-faced Dude," so here's a "blueberry dude" also from Tattoo Disasters.

On a related note, we seem to be adjusting to the fact that not only do we look, we are looked at. It's probably because of all the benefits of being under constant close scrutiny..
(From Noise to Signal) Sticking with the meme of "look," here's a new look for a couple of old icons that made me look twice before the joke sunk in:
This is a t-shirt design promotion for AAAS (the American Association for the Advancement of Science). Hat tip to Arizona Geology for bringing it to my attention. Now as strongly opinionated as people are over whether or not "evolution" should be taught, I get very frustrated over how little they understand it. "Evolution" in its current colloquial usage simply means "change through time," and no one disagrees with it. The issue is, more specifically, how do living things change through time. In broad strokes, Darwin got as close as anyone could have hoped. People generally don't realize how contingent that elegant piece of work was upon accptance of the conclusions of much earlier revolutionaries...
From Abstruse Goose; click over for the full comic. You have to wonder what he would think of this:
I am assuming (and praying) that's a photoshop job; I live too close to the ocean (about 50 miles as the crow flies) to feel safe if that thing and its family are running around loose. (From Serious Lulz) I'm also curious what Che Guedarwin would think about the current educational controversy over his theory (despite what you may hear, there is no controversy about the general characteristics of the theory amongst scientists, only over the details.)
(From Saturday Morning Breakfast Cereal) An aspect of evolution that has always fascinated me is the way individuals of different species can cooperate to the benefit of both. Symbiosis, or more accurately, commensalism, can lead to seriously awesome combinations of strength, guaranteed to overcome all potential enemies...(Serious Lulz) Convergent evolution is another fascinating aspect of life on earth in which, because of similarities between the functions two dissimilar organisms need to perform, their body shapes, or morphologies, are pushed by selective pressures to look very similar. So, for example, the forms of sharks and dolphins are quite similar, because they both benefit from being streamlined. The forms of dolphins and the now long-extinct ichthyosaurs are even more similar. Likewise, for many birds, having a flashy crest or elegant, colorful tail can help attract mates. For the Pope... well, no, I guess that doesn't quite work out...
pope totally looks like cockatoo
see more Celeb Look-A-Likes. The Pope's official stance on Priests, Rabbis and Bars is worth noting too. Even if that flashy crest won't help him when he delivers those great, Vatican-approved pick-up lines.
song chart memes
see more Funny Graphs. And afterward, we can have a driving contest!
(Criggo) I don't like bar fights, but I've seen a few. I don't think they can end well, but sometimes they end less badly. And sometimes worse.
hugo weaving
see more Lol Celebs. I've never witnessed anyone get killed, but I have seen someone suffer heart failure. It's pretty scary...
donald rumsfeld, george w. bush and dick cheney
see more Political Pictures. The best kinds of fights are imaginary: you can't really loose, and no one actually gets hurt...

This kind of fight will rarely end in physical injury, but can be psychologically devastating:
song chart meme
see more Funny Graphs. But here's one woman I wouldn't want to exchange fisticuffs with:
(From Pundit Kitchen) In food news, Kittehs all over the world let out a cheer when they saw this, from Serious Lulz:
"The way you see others reflects what's inside of you.
Which is why everyone today looks spicy and Mexican."

But that does not mean everyone is going to be super-tolerant when you get on the elevator afterward...
engrish funny considerate air
see more Engrish. In fact, if you disobey the sign, you may be sent off for a sojourn in the delightful spot:
Oddee had a funny piece on the consequences of letting random neon sign letters burn out; the above is one of them.

As I've noted, but still haven't put aside time to really discuss, we've had some unusual weather here in western Oregon this week: very warm and muggy, with some wild clouds on Wednesday and what appears to be a record-setting storm on Thurday. The key to good weather reporting is creativity: mix it up so the audience stays interested.
From Criggo, of course.

Well, it's finals week here at OSU, and a week from today a new class of graduates will take to the field and listen to the wisdom and recommendations of an inspirational speaker, before moving on to the next adventure of their young adult lives. CJSD offers ten important points (five more at the site) these graduates should ponder.

10) I look out here and see young, energetic faces ready to take the world by storm. Well, if any of you even think about trying to take my job, I'll fucking shank you.

9) Cherish this time you'll spend living at home until the economy improves.

8) Many of you leave college perhaps with more questions than answers, wondering what will happen when you walk across this stage and depart this campus. Except those of you in ROTC, your orders are taped to your diplomas.

7) For the love of God, use spell check.

6) Once you get out to the "real world," there will be times when you're confronted with things that shake the very foundations of your beliefs: The theory of evolution. The geological age of the Earth. Female orgasm. But in those dark times, remember this: you have something stronger than facts. You have an education from Bob Jones University.
So here's wishing "Good Luck" to all my young friends this week. Try not to stress out over finals; they're really not as important as you think. Assuming, that is, you actually took advantage of your opportunity to learn the material, rather than just cramming it into your head for a few hours so you could pass a test. In that case, you should probably just skip your finals and start over with your freshman year.