Tuesday Geology Photo

As part of the geology-photo-a-day week, here's my photo for today. This was taken en route to doing some field work in late August 2010. It is of the Cardium Formation (one of Alberta's most prolific reservoir formations) at the spectacular Ram Falls in the foothills of west-central Alberta.

Monday Geology Photos

Evelyn at Georneys invited us to join her this week in posting a geology photo a day. It's a busy week for me, trying to finish the final chapter of my thesis before I settle in for some thorough editing. I can't promise that I'll get around to finishing the blog posts I have in the works, but a photo-a-day seems manageable, especially since sifting through them to find especially cool ones makes for a nice break.

Today's photo is from my visit to Australia in September. It's from the top of a red sand dune, between Lake Amadeus and Mount Connor, in the Northern Territory. I forgot to take a close-up photo of the sand, but it was hot and fine-grained and felt silky smooth on my bare feet.

The pinkish haze on the horizon is the smoke from the bush fires that were a dominant character during my time in the Northern Territory.

It's kind of cheating on the photo-a-day theme, but here's another photo, showing a different dune in the background, giving a sense of how big these things actually are.  In fact, many of the viewing areas at Uluru and Kata Tjuta are on top of dunes.

If you fly to Alice Springs from Sydney, as I did, you fly over the Simpson Desert, which is a "sea" of dunes.

All Geology Is Connected

Yesterday, after attending a talk that got me thinking, I tweeted this: 

At a talk about how/where diamonds form I heard about "diamonds" that plug gas wells #AllGeologyIsConnected

The talk was part of the colloquium series in the department where I'm a grad student. A couple of the faculty work very hard to bring in guest speakers every two weeks to give talks about various aspects of geoscience. The room is never full for these talks. I know not everyone can make it to every talk, but I also suspect some people don't come to these the talks if they are not "relevant" to their own research. They're missing out.

I have geologic interests outside of my own research. I want to learn about other aspects of geology. Besides which, I find going to "unrelated" geology talks sparks my thought process, and I sometimes get new ideas for how to present/explain/display something I'm working on.

More importantly though, all geology is related, in a broad sense, and you never know what background info you are going to need to call on to solve a problem.  Today's colloquium talk, or rather the discussion at the end of it, was a really good example of this.

The title of the talk was "Diamond: Deep Carbon from a Shallow Source." The abstract can be found here. It was about isotopes and eclogite and peridotite and diamonds and inclusions. I'll admit, most of the details were beyond me, but I still learned something from it, and I was surprised at how much I could follow (it seems going to talks "unrelated" to my research is paying off, and I'm learning new stuff).

The questions at the end were really a discussion on the still-unknown stages of the formation of diamonds. But someone in the audience had insight that yielded a "wow" from the speaker. It was a petroleum geochemist who specializes in carbon sequestration and biodegradation and other important stuff like that. It might be a bit of a stretch to say that these two researchers, although both geologists and both geochemists, don't have overlapping research (but let's pretend they are completely "unrelated," for the sake of my argument). The petroleum geologist suggested that diamondoids, which are found in petroleum and actually clog up gas wells, might have clues about some of the unknowns.

Wow.

Most of us were chuckling over the idea of "diamonds" clogging up gas wells, but we could still see the wheels turning as the speaker thought about this new approach to his research and the possibilities it might yield.

My point in all of this, besides the fact that it's kind of cool that there are diamonds that plug gas wells, is that all geology is related and doesn't have to be directly connected to be relevant. And that's pretty cool.

Thinking about not looking up from the path you're on reminds me of something that happened when I was in Bolivia doing field work...

Coming around the bend towards the end of a day in the field, we were so focused on the path in front of us that we almost missed this biotite-bearing outcrop that provided age constraints on the beds we were mapping.  

That's right, we almost missed this outcrop.

Now as it turns out, even if we'd missed the first one, there was still lots of ash around to collect samples from.

But this one is so cool...

In so many ways.

Rugby distraction

I've been distracted for the last two months, partly because I was away for 5.5 weeks, and partly because the Rugby World Cup was on, and I'm a huge (All Blacks) fan.  In fact, my overseas trip was so that I could catch a bit of the rugby in New Zealand, which is like home to me.  I did mix in some geology with my travels: I was on a volcano, I visited some ancient clastics and some modern carbonates. I even did some work on my thesis and a manuscript my supervisor and I are working on. And I watched a lot of rugby, on TV, and in the stadium. I went to five games: three pool matches and two quarterfinals.

When I came back to Canada, I struggled to get over the jet lag, because the rugby was still on, and I was up until 4 or 5am watching the semifinals, and then the bronze final, and then the final. SPOILER: A week later, and I'm still pretty elated about the results.

Now that the RWC is over, I need to get my nose back to the grindstone and finish off my thesis and that manuscript. They're getting there. I'm struggling a bit though, because I'm in rugby withdrawal. So last night I went through some of my photos from Australia, and printed off a few from my outback trip, so that I could look at the really cool geology and be motivated to get some writing done. It also got me thinking about the things I saw that I want to blog about, so now I have a list, and a schedule. Hopefully it will be a nice distraction from writing and figure-making. Anne Jefferson's writing challenge couldn't have come at a better time.

In the meantime, here are a few teaser pictures from my time away (and if anyone knows how I can save them so that the colour doesn't sometimes get changed when they are being viewed, I'd be grateful):

Beside a fumarole on White Island

Fumaroles!

Uluru

Valley of the Winds, Kata Tjuta

King's Canyon

Standing beside the Webb Ellis Trophy, two weeks before New Zealand won it

Foreland basins in a nutshell: Part III - Retroarc and peripheral foreland basins

Part I
Part II

The Western Canada Foreland Basin (WCFB) is a retroarc foreland basin. There are two main types of foreland basins, retroarc and peripheral. Both form during collisional tectonics.

A peripheral foreland basin, also known as an Alpine-style foreland basin, forms on the subducting plate (usually during continent-continent collision).

A retroarc foreland basin, also known as an Andean-style foreland basin, forms on the upper plate (usually during continent-oceanic plate collision).

Note: nothing is implied in the scale of the two figures above: there is definitely some vertical exaggeration going on.

I've often wondered if there is a difference in the sediment deposition patterns in the two classes of foreland basins. A reading of Hugh Sinclair's 1997 paper, Tectonostratigraphic model for underfilled peripheral foreland basins: an Alpine perspective, in which he describes the "underfilled trinity," (a favourite term of mine, by the way) felt a lot like reading a description of the Jurassic succession in the WCFB, except that he was describing a peripheral foreland basin. I suspect, therefore, that the sedimentological record alone would not be enough to discriminate between these two types of foreland basin.

In fact, this is what has been found by other authors, such as Dickinson: "Designation of a given foreland basin as either a retroarc basin or a peripheral basin thus depends upon a knowledge of the sequence and timing of tectonic events in the adjacent orogen" (Dickinson, 1974, p21).

Why does this matter? Well, having an "underfilled trinity" in the WCFB means that the foreland basin depositional sequences began appearing sooner than everyone thought, and that fits with what I'm proposing with my research. It also means that although foreland basins contain a record of the adjacent orogeny, we cannot use the basin fill alone to say if it is a retroarc or a peripheral foreland basin. It may seem strange that we wouldn't know this, but recent, and controversial, hypotheses about the evolution of the western margin of North America imply that the western foreland basins are peripheral, not retroarc (and by mentioning this, I'm not saying that I agree with those hypotheses).

In part IV, I'll talk about foreland basin fill: flysche, molasse, backbulges, underfilling...

References:

Dickinson, W. (1974). Plate Tectonics and Sedimentation. In W. Dickinson (Ed.), Tectonics and Sedimentation (pp. 1-27). Society of Economic Paleontologists and Mineralogists.

Sinclair, H. H. D. (1997). Tectonostratigraphic model for underfilled peripheral foreland basins : An Alpine perspective. Geological Society of America Bulletin, 109(3), 324-346. Geological Soc America.

Childhood memories

A recent twitter discussion that began with me wishing there was a "Tectonics for Toddlers" I could give my nephew got me thinking about one of my favourite toys as a preschooler. It was a Fisher-Price hiking set, and I used to hike around the neighbourhood with it. I always dreamed about going to the coulees behind our yard, but that was forbidden territory to little me (and rightly so--I was only about five years old at the time).

My hiking set is long gone, and a recent Google search turned up an picture of the set in an "old toys" website. But when I go out in the field these days, I still carry some of the same tools, just more grown-up versions of them.

Missing from this picture is the compass that had a mirror on the other side

Accretionary Wedge #37: Sexy Geology

My preference is for big picture geology, especially studying how tectonics influences sedimentation. For this, you need to understand a little bit of everything (or at least be willing to contemplate it). My undergraduate background in geophysics is helpful for understanding geodynamics, and living and studying in Alberta has meant that I've had ample exposure to sedimentary geology in both my degrees. That being said, there are a couple of sedimentary structures that make me swoon. I love a good cross-bedded sandstone. But the one that really gets me is ripples.

I know ripples are pretty common, and I know they aren't great paleocurrent indicators. They are, however, good environmental indicators and for me, seeing a big rippled surface in the field is pretty exciting, especially when it is far away from anywhere it could have formed. What excites me is that they are evidence of tectonics. They've been buried, they've moved,  they've been uplifted and they've been exposed.

There's just something about being up on a ridge, far away from any water and even farther away from a beach, and seeing ripples. It's sexy geology.

Ripples on Dinosaur Ridge, Colorado.
Embiggen to see the scale bar in bottom left.

Ripples in the Puchuni Valley, on the Bolivian Altiplano.
No scale, because this was above me on a narrow path on the edge of a steep hill.