Just wanted to put out a reminder to the geoblogosphere about this month’s Accretionary Wedge #54- On The Rocks: Geo-Brews and Geo-Cocktails. This month we’re celebrating our favorite geology themed libations. You can either come up with a geology inspired cocktail, brew or even just share your favorite, all-ready made drink. And if you don’t drink, that’s okay, too. Feel free to come up with a non-boozy version of your preferred beverage. Need inspiration? Check out Michael Klass’s contribution on his blog over at Cascadia Blog. When you’ve come up with your contribution, post a link in the comment section of this post and I’ll compile all the posts at the end of the month. I’m looking to have the posts collected by the 28th or 29th, so they can be ready to go on the 31st (hey… it’s still January). Have fun!
I’ve always maintained that if someone wants to know the solar system, study meteorites. They are literally the left over building blocks of our solar system and give us an unparalleled insight into the solar nebula from which our planet and the others formed. We can use mathematical models to hypothesize the accretionary process, but the chemical composition of meteorites and chondrules help us to constrain the results.
Meteorites become even more impressive when we look at how they’ve influenced the human species over the course of our relatively short history. Meteorites were often considered messengers from whatever gods were worshiped by people in that area. Some stony meteorites were carved into religious figures, while the iron meteorites were turned into jewelry or even the first metal hunting weapons. Regardless of the civilization, from Egyptian to North American Indian tribes, meteorites served to connect people to their deities.
A new paper in the September 2012 Meteoritics and Planetary Science, Buddha from space, further explores this interesting topic by looking at one religious figure in particular, the Hindu god Kubera (or Vaisravana in Buddhism). This god is considered the Lord of wealth and North-direction and can be found on many statues. This article from MAPS looks at one that is possibly carved out of the iron meteorite, Chinga.
The Chinga meteorite was discovered around 1913 in the Tana-Tuva region of Mongolia and Siberia. Researchers have used glacial depositional features to estimate that Chinga landed in the region approximately 20,000 years ago. Based on the best known age of the swastika, the statue itself is probably around 3,000 years old. In 1938 it was recovered by Ernst Shafer while on an expedition for the German National Socialist Party.
This statue is unique for a couple reasons: 1) it’s an ataxite. This type of iron meteorite is composed of at least 16%-30% nickel, and as such, doesn’t display that beautiful cross-hatched widmanstatten pattern for which iron meteorites are known. They also are among the rarest of iron’s and don’t fit easily into a classification scheme. 2) It’s thought by historians that this little figure is what gave rise to the swastika symbol used by the Nazi’s.
Based on their chemical analysis, Buchner et al., were able to conclude that the statue was made from an ataxite. However, the concentrations of certain elements puts it into an ungrouped category (of which Chinga is part of). When classifying irons, meteoriticists look for the weight percent of Fe, Ni, Co, Cr, Ga, and Ge. It’s that quantity that allows for an iron meteorite to be grouped with others, or even allows us to determine if it belongs in its own group. The researchers do report some problems with the Ga and Ge readings, but they attribute this to the very small sample they had to work with from the statue.
No, I didn’t make that name up nor is it the name of some 50′s sci-fi show. The name refers to a time period from nearly 460 million years ago when the earth did look quite alien. It was a time when the continents as we know them weren’t in their present positions and life was dominated by trilobites, snails, clams and other seafaring creatures. The Ordovician occurred right on the heels of the Cambrian period when life first started to make it’s appearance in the fossil record.
At around the same time, another important event was occurring in the solar system: the break-up of the L-chondrite parent body. An L-chondrite is a type of stony meteorite that is relatively common and has a low abundance of iron. Most of the L chondrites are heavily shocked and share other chemical commonalities. This has led researchers to hypothesize that L chondrites came from the same source. With this break up of the parent body came an influx of meteorites that would impact the earth; some of which would land in shallow water among the sea creatures of the Ordovician. Those creatures would die off and become the limestone layers in which those meteorites would be encased.
This particular image came from a group of researchers that examined a limestone outcrop from a quarry in Kinnekulle, Sweden. They analyzed the distribution and size of meteorites in multiple layers of limestone in order to constrain the influx rate of the meteorites from the parent body break-up. In total, the researchers retrieved 40 meteorites from about 3 meters limestone, or about 10 feet.
What’s really interesting is that not all layers yielded an equal amount of meteorites, nor were they of equal size. Some layers only had one, while another had six. One layer, the Arkeologen, put out 26 meteorites! What this tells us is that we had multiple falls from possibly the same event. And keep in mind, these fossil meteorites were found in a relatively small area. Of the known 3300 m^2 of the Arkeologen,only about 2700 m^2 of it has been searched for meteorites. Stratigraphically, we can assume that more meteorites could be recovered from the formations across a broader area. They were able to use this information to determine that there was an increase in meteorites delivered to the earth at that time.
One of the difficulties with pairing meteorites from this location is the extreme calcification that occurs from being trapped in limestone. Meteorites tend to crack and weather easily on the earth. This can cause internal alterations, such as oxidation, that chemically alter the meteorites. However, Schmitz et al., were able to use relict chromite grains as a way to possibly link them to the same parent body.
- A rain of chondritic meteorites in the early Ordovician. Schmitz, Birger., Tassinari, Mario., Peucker-Ehrenbrink, Bernhard. Earth and Planetary Science Letters. Vol. 194. Issue 1-2. P. 1-15. DOI- http://dx.doi.org/10.1016/S0012-821X(01)00559-3
- The Ordovician Period- University of California Museum of Paleontology.
No, I haven’t forgotten about my blog nor my readers (all two or three of you). I figured after the end of the Fall Term I would have more time to write and get back to spreading the joys of meteorites, science, and whatever else caught my attention. Something I didn’t take into account was a little thing called an abstract. I’m at the point in my research where I have enough data to finally start telling a story about my meteorite. The goal is to have an abstract submitted for a poster and accepted for the Lunar and Planetary Science Conference in Houston in March. The dead line is January 9th and with me being gone in San Francisco from December 23rd to January 3rd, I’m under a lot of pressure to get it out of the way.
I still have my basic duties in the meteorite lab, too. Primarily that of responding to e-mails when people think they might have a meteorite. This is a task where I can easily just say “no, you don’t have one” and move on, but I use it as a chance to tell them what they possibly have and why it’s not a meteorite. Some of the e-mails get kinda long as there are some people who like to argue that their river rock is indeed a meteorite. Or better yet, argue with me as to why they believe they have a martian meteorite. It’s science outreach and something I do take seriously. Even when someone tells me that they’ve buried half of their meteorite because they don’t want NASA coming to take it (true e-mail).
But most of my time has been spent processing data from the SEM and learning geochemistry on the fly. I’ve probably learned more from my work in the meteorite lab than I have any other class. I’m starting to become familiar with cooling rates as ascertained from Fe-Mg diffusion distances and now I’m reading a paper on the solidification of metal-troilite grains in chondrites. All of which is needed for the completion of my abstract and to give me a general background of meteorite fundamentals. I’ve enjoyed my project so far, but it’s also been very intimidating. I keep thinking one day I’m going to get exposed as a fraud who really has no clue what the hell he’s talking about. In my head, that conversation revolves around not knowing the difference between lodranites and acapulcoites. Or, even worse, differentiating between LL3.1 and LL3.2. Okay… So, I’m being a bit dramatic, but that imposter feeling is still there.
I just keep repeating to myself that I’m never going to amount to anything if I’m not willing to look stupid from time to time. It’s in that spirit that I keep moving forward even when I think I would have been better off in a squishy major.
I’m not going to mince any words: it’s been a busy term. Hence my month long hiatus on the blog. My term has been busy with stratigraphy and sedimentation, scanning electron microscopy, a course on the history of modern science, and my usual work in the meteorite lab. The greatest amount of my time has been dominated by stratigraphy. A couple weeks ago I spent four days on the the southwestern coast of Oregon studying uplifted marine terraces and more shale than I ever wanted to see. In all honesty, it was like the twilight zone of geology. At one stop, the rocks got progressively younger as we went from south to north along the beach. Drive north a few miles and the rocks actually got older as we went in the same direction. To further add panic to the confusion, our instructor would ask which way was upsection, or in which direction were the rocks getting younger, and if you got the answer wrong you did push-ups or sit-ups. Not wanting a repeat of junior high hell, I learned to become very comfortable with my compass and topo map. Staying out of my professors line of sight was effective, too.
I wasn’t sure what frightened me more on this trip: Houses built on mud, such as this one:
Or the tectonics off Oregon’s coast with the ability to turn once horizonal rock layers on their side:
My favorite stop was Cape Arago. It was here that I finally understood what I was seeing. I spent most of the trip feeling lost, confused and cursing every layer of mud that I had to map. Cape Arago used to be an old submarine canyon. Then the ocean receded and slowly exposed the canyon and its cut and fill sequence from a probable paleodelta. And I saw a lot of seals. Double win.
It was also at Cape Arago that I learned how quickly I can map an area. Nothing makes you work faster than hearing your instructor say you have three hours and the tides are coming in.
Then there was Shore Acres. This was our last stop on the trip and it proved to be the most mind-boggling of all the sites we visited. And the weather turned to crap, too. Mother Nature decided to keep the wind and rain to herself until us lowly undergrad geology majors were exposed on the point. It was at this site that I learned even rite-in-the-rain notebooks have their limits.
Day two of our trip found us doing much of the same thing as yesterday: mapping fluvial and volcanoclastic deposits. This time we learned how to measure strike and dip of the observed bedding. Here’s an aerial view of our work area:
This out crop is where we spent most of our time taking measurements. What you’re seeing is some severely tilted beds of volcanoclastic material. The dip is nearly 60 degrees at the top and becomes less angled as the bed continues dipping.
A slightly closer shot of the same area:
Here’s a close-up of the clasts present in some of the bedding:
The source of the tilting is probably some plutonic intrusion. I’m inferring this based on the presence of a sill that sits just to the left of the first set of tilted bedding.
Here’s the view at the top of the basaltic rimmed plateau. Not sure if my camera got it, but you can see Mt. Hood in the background.
Day one of my strat trip found us mapping fluvial and volcanoclastic deposits in the Cove Palisades State Park. It was nearly four hours of hiking up the road, examining the road cut, and taking measurements. What did we find? Lots of fluvial deposits such as rounded cobbles and sand stone towards the lake and volcanic teffra towards the top. Here’s a few pictures to show the sequence. I included scale where it was safe to do so. I can’t get into too much detail because I’m posting this from my phone.
Our work area seen from the top
Layer of cross-bedded sandstone on the bottom with rounded cobble on the top. All indicative of fluvial deposition.
Welded ash with pumice
An example of beautiful cross-bedding in sandstone
The meeting of fire and water. The rounded cobbles at the bottom were deposited in a fluvial environment. The thick layer in the middle is from an ash flow, while the layer directly above it is ash fall. The later directly above that is more rounded cobble.
Another example of beautiful cross-bedded sandstone and gravel.
And to end it all, nice columnar basalts.
Because I need a break from homework and everyone loves an awesome scanning electron microscope (SEM) image.
Isn’t it gorgeous? This image was taken during my SEM course last week and was part of my homework. We’re learning how the SEM works and taking cool pictures in the process. This is a shot of some antenna filament on a mayfly. I can’t tell you much more about it, but you should click on it anyways to take in the hi-res splendor.
Today’s Meteorite Monday is a special one to me for two reasons: 1) I get to formally introduce my brand new meteorite and 2) this is the first time I’m updating my blog from WordPress’s mobile app. I love technology!
I posted pictures of my new jewel on Facebook, Twitter and G+ already, but I thought it appropriate to share it on the blog, too. Especially since I haven’t updated in a while.
Here she is, Northwest Africa 7109:
This gorgeous specimen was purchased at our fund raiser on Saturday. It was actually bought by a good friend of mine, Dave, and he gave it to me because I was smitten by it when I first saw it. Not only did I get a new meteorite, but the lab got a portion of the sale to apply to our research. So I wanna give a big thanks to Dave for that! Also, big thanks to those that either donated directly to the lab or purchased meteorites. Your contributions are greatly appreciated and further the exciting science we do in our lab.
The particular meteorite I was gifted is an L5. The L refers to a low metal content and the 5 refers to a relatively high degree of thermal metamorphism. In spite of that, some chondrules are still visible. That nice big broken one in the center is a good example. The piece is pretty well weathered as can be seen from it’s rust colored appearance. I believe the dark colored patches are the result of shock blackening, but that’s just a guess.
I fell in love with this sample because it’s a great teaching resource. It contains all the hallmarks of a meteorite: metal flecks, some shock features and, most importantly, chondrules. It’s the type of meteorite that I’m not afraid to break out of it’s case and let people touch and examine. And that’s incredibly important when getting people excited about meteoritics and science in general.
I talk a lot about my work in the meteorite lab. My time here has taken what could have been a cookie cutter geology undergrad experience and turned into something far more educational and worth while. It would be one the biggest understatements of my life if I said I didn’t feel some sort of connection and debt to the lab.
And it’s for this reason I want to get the word out about our annual fund-raiser. Every year for the past six years, CML has had a get together and fund raiser. The purpose of this event is two-fold: to give donors a chance to see how we utilize their money and to further raise funds for our operations. CML is part of the Portland State geology department, but we are financially independent of the school. We are given space and office equipment, but any funds for thin section production and analytic work (SEM,EMP, etc..) comes out of CML’s own funds. We do have an endowment of sorts, but we’re only able to access the interest generated. It’s enough for a project or two, but not much else. For all other work we have to raise money or apply for grants.
The fund raiser serves as a meet and greet where space science and meteorite enthusiasts can talk with one another and tour our lab. There’s a potluck for food and we also have a silent auction on meteorites. Or if you prefer to not bid on a space rock, you can buy one outright from a couple of the dealers that normally come to the fundraiser. All purchases, regardless if it’s from the silent auction or bought from a dealer, benefit the lab either directly or indirectly.
This year is going to be a little different. Brother Guy Consolmagno, also known as the Vatican Astronomer, will be speaking about the Vatican’s meteorite collection. Some might scratch their heads at the idea of someone being a scientist and working for the Catholic church, but Brother Guy is legitimate. Check out this interview to see what he’s all about.
Here are the details for the event:
- When- September 15th from 2-6 P.M. Brother Guy’s talk starts around 3 P.M.
- Where- Cramer Hall at Portland State University. The pot luck will probably occur in the Geology Office in room 17. Look for the trail of space nerds and you’ll be set.
- Who- Everyone is invited. It doesn’t matter if you’ve donated to the Lab or not.
Something I greatly want to emphasize is that this is a fund-raiser. Even if you can only chip in five or ten bucks to the general CML fund, please do so. Every little bit helps and we’re not looking to get hundreds of dollars out of individuals. Although we certainly won’t say no if someone is feeling extra generous. And if you can’t make it to the event, but would like to donate, this link will take you to this years newsletter. It not only talks about all the awesome work we do, but also has a form with instructions on how to donate to the lab. You can donate to either the E.F. Lange Endowment or the Cascadia Meteorite Lab Fund. If you do decide to donate, please consider giving to the CML fund as we’ll be able to use all of the donation instead of just the interest generated from it.
For more information about the event visit our website.