Shifting Gears and Changing Lanes

I suppose this blog post is long overdue. This summer I was in Houston, Texas working as a geology intern for a major oil corporation. I had a great time working for the company and made a lot of friends. Some of whom I’m looking forward to seeing at the upcoming GSA meeting in Denver.

I also worked with seismic reflection data for the first time. I became fascinated by the data and the large scale structures it allows the interpreter to see. While I was diving in head first I read a short guidebook on seismic interpreting. First Steps in Seismic Interpretation by Donald A. Herron really helped me out as I was getting used to thinking about seismic data. I liked it so much that I was planning on writing a book review, but Thomas Martin wrote one for Agile Geoscience and beat me to the punch. I agree with his review, so writing another would be redundant, check it out!

Although this summer I didn’t work in salt, the exposure to colleagues work got me fascinated with salt tectonics. I hope to be working on salt structures in the future and have plenty of ideas for blog posts.

While in Houston I was working nights and weekends tying together my PhD proposal. Defining my project was a stressful, eye-opening, and educational endeavor. However, after a short rock climbing vacation in California, by the time I returned to Montreal I was feeling the pull of different winds. I’ve decided to switch from a PhD to a MSc. I have enough data that I can go ahead and write up the work I’ve completed. When faced with 1 more year or 3 more years in Montreal, I decided that I was ready for a change of pace and to try the world outside of academia.

Looking forward to the many adventures to come!

http://freakonomics.com/2011/09/30/new-freakonomics-radio-podcast-the-upside-of-quitting/

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Hiatus

Hurricane Deck
Hurricane Deck

Posts have been sparse since December. I haven’t even finished going through my notes from AGU for posts! I have a bunch of half-finished posts that will have to wait.

This semester is especially busy for me. See, I have my qualifying exam coming up and all my efforts will be focused on slaying that task. I will find time to go to the rock gym on the weekends. There’s a slim chance I’ll write some posts based on my thesis research if it helps me get my mind around it / practice explaining it. In any case, you’ll hear from me in late April / May.

Cheers,
Tim

Rock n Roll fault rocks: a pictorial journey aka my Namibian field season

So my last post was a tiny tiny update. I should write more about what I’ve been up to the past month and a half. First off, this has been an incredible adventure. Namibia is amazing. This was my second time to Africa (South Africa and Namibia). I’m currently living in the Geo department flat at UCT. Thank you to the department staff, and Tanya and Jacq for helping Ben and I get settled.

EDIT: Click any of the pictures below for a larger view!

I know, I know, you want to see rocks. Bear with me. Let me give you some context.
So where in Namibia was I? Where the hell is Namibia!?

Let’s zoom in:
-24.262224, 16.2432

Naukluft Nappe Complex
That’s about 200km South-Southeast of the capital city of Windhoek as the crow flies. 

The Naukluft Nappe Complex is a thrust fault system associated with the Damara Orogen (~550Ma) that emplaced meta-sedimentary rocks in a roughly Southeast vergence on undeformed basin sediments. This area was originally studied by two German geologists, Henno Martin and Herrmann Korn, in the 1930s. These two geologists would later live two years in the Namib desert hiding (and mapping!) during World War 2 (blag post on that coming soon). They divided the complex into three different nappes, though more recent mapping has established five nappes. Korn and Martin also made the observation of a fault rock they describe as the “Unconformity Dolomite”. You know how geologists love to name stuff. First it was “Unconformity Dolomite”, then other authors called it “Lubricating Layer”, then other authors called it “Sole Dolomite”. From now on let’s agree to stick with the sole dolomite convention.

Carrying on, this sole dolomite is the a layer of rock that separates the footwall sediments, blue limestone and shale, from the hanging wall, which is a charlie foxtrot of dolostone, quartzites, and shales. Want a photo of what this thrust looks like? Check out the header for this blog! Oh, you’re too lazy to scroll back up? Okay, here you go:

Naukluft Thrust

and at another location:

Naukluft Thrust

Did you spot the fault yet?

I have so many pictures of this thing it is ridiculous. Tons of panorama shots too. Sadly, the GigaPan uploader can’t get through the UCT firewall, so we’re all going to have to wait until I’m back in Montreal to see those panoramas. It’ll be worth the wait. I’m getting ahead of myself.

So what does this sole dolomite look like? It’s the brown-tan bed on the blue limestone in the above photos, but let’s move a little closer…

Ben (Dr. Choff) for scale

The limestone at the fault margin is mylonitized. Enough teasing, let’s look at the rock.

Slicks!

As you can see there is a foliated zone of dolomite at the fault surface. How about that rock above it though? That’s called “Gritty Dolomite.” It is a “cataclasite-like” fault rock that has dolomite phenocrysts, lithics, and silica. It looks like this:

Gritty dolomite with silica banding.

But sometimes it looks like this:

Discrete gritty dolomite layer between sole dolomite (below) and a dolomite breccia (above).

Or even this:

Uhm, what? Laminated and folded (flow-folds?) gritty dolomite. Some silica banding.

But sometimes it does this:

Footwall limestone clasts in a gritty dolomite / sole dolomite breccia. A brown silica cortex surrounds footwall clasts.

And how about up on the ridge (picture from this blog’s header and picture #2)… BAM!

That is a RocknRoll breccia if I’ve ever seen one.

Sometimes the gritty dolomite will inject upsection/downsection off of the fault, sometimes looking like this, often found with neocrystallized dolomite, sometimes doubly-terminating neocrystalline quartz on the surface:

This rock is from part of a clastic gritty dolomite injection.

And these photos are only on the eastern side of the nappe. Okay, okay, so WHAT were we doing out there? We were mapping this fault with a pair of these:

Ben desires more satellites.

The Trimble GeoXH. We set one up as a base station. The other is a rover. We walked the fault, making observations, taking measurements, ect. Once home I load the rover file with the corresponding base station file into the Trimble TerraSync software and presto! Centimeter GPS accuracy! As a first order question, I’ll be looking at how the geometry of the basal fault relates to the type of fault rock observed, injections, and make interpolations of the fault surface.

In the eastern side of the Nappe typical fault dip is betwee 15-25 degrees, but varies widely. Now on the West side…

Tsams Ost locality

Can you spot the fault? Hmm… that looks a bit different. Typical fault dip here is ~3 degrees. The foot wall is typically blue shales, and there is no gritty dolomite to be found. We do observe the occasional footwall shale injecting up into sole dolomite…

Footwall shale injecting up into sole dolomite.

There’s also some fantastic folding in the hanging wall.

Hanging wall folds.

I feel like I could continue on and on posting pictures, so I’m going to force myself to stop. I’ll put up a gallery of photos on my Google+ page in the near future. I’m incredibly eager to get back to Montreal to look at the GPS data and start piecing this puzzle together.

Special thanks to Ben Mapani for his invaluable assistance and advice. Thanks to Ben Melosh, Jodie Miller, Clint Isaacs, Rangers of Tsams Ost, and my advisor Christie Rowe. An extreme thank you goes out to the Naukluft 9 park staff for their generous hospitality and assisting with charging of our GPS batteries.

Desert graffiti. 

Yellow Bank Creek Complex #SciWrite DONE! and more news

So I finally finished my #SciWrite manuscript. I just submitted a manuscript to G-Cubed: Geochemistry, Geophysics, Geosystems. The manuscript was based on my undergraduate thesis at UC Santa Cruz on the Yellow Bank Creek Complex, the world’s largest known exposed sand injectite complex. It’s an amazing outcrop. I’ll be writing a field trip guide for the outcrop in the near future, a version of which will be posted here. I’m very excited to finally get it off my desk. Now I can get back to blogging! And onto planning summer field work, grading those labs…

Northern side of Yellow Bank Creek Complex outcrop. Yellow-tan sandstone is limonite cemented. Blue-grey sand is dolomite cemented.

Also, now that I have a submitted manuscript I updated my CV with it and finally set my McGill webpage live. I have a lot of awesome pictures posted there. Check it out. Please if you have any comments about that site (or this site too!) I’d love to hear feedback. Am I missing something crucial to my webpage that every grad student should have?, ect. Let me know!

I also want to work on a re-design for this blag, that’s on my farthest backburner, though. Any ideas?

Don’t be a putz, scan your notes

Recently I went on a week long field trip to Texas for a Basin Stratigraphy class. I took along my notes as well as some unrelated papers that I needed to read. By the end of the trip I had lost my notes and the papers.

One useful student-thing I got in the habit of doing my senior year at UC Santa Cruz was scanning my class notes. There was a color scanner on the office copy machine that would email me pdfs of my notes. Perfect. I could access my notes from anywhere (via DropBox) and if my notebook exploded, I had back ups.

I got out of the habit and am regretting it now. With my notes gone, I’m a bit stuck with nothing to reference back to.
So as a quick tip: SCAN YOUR NOTES. CLASS NOTES, THESIS NOTES, WHATEVER. Not only will you be able to access them anywhere, but you’ll have a backup. Do it.

Under Attack: What to do when your poster is under fire #AGU11

I by no means am offering solutions to this. Instead I hope readers in the comments will help out by posting their past experiences with this situation and detailing how they’ve handled it. That said, I need your help to make this post work! First, my poster experience.

My poster session at #AGU11 went really well. I was at my poster for the full four hours and never got a chance to leave. I was talking the whole time and getting great, positive feedback on my research, and some ideas of where to take it further. 
One gentleman did attack my work. The primary discrepancy came in the fact that he disagreed with outcrop features that I had interpreted as being cross-cutting. He had not personally been to the outcrop, but it was difficult to continue the discussion into the more interesting parts of my research because he would continually cut me off with “that’s not cross cutting.” Basic outcrop information that I had gotten across to everyone before (and after) was not getting to him. I must say it caught me off guard. This was my first time presenting a poster, and I was not sure how to handle this situation. I did my best to have a discussion with him, but it was very frustrating. 
Overall my first poster presentation was a positive experience, and it reignited my drive to finish my #SciWrite manuscript.
So please, readers and fellow GeoBloggers, if you (and/or research) has been attacked at a poster session please post the story and your insights in the comments section!