Friday Rocks 1

Lately I’ve been posting some photos from my research trips to Instagram and I thought why not repost them here in better quality. Every Friday I’ll post a new photo of a rock landscape with some description and light interpretation. Enough talk, let’s see the rocks.

Lens cap is 72 mm

Here is a piece of laminated “gritty dolomite” in float from Naukluft-Zebra Park, Namibia. Gritty dolomite is a fault core rock that deformed via granular flow during coseismic slip. Laminae resemble flow bands. Here a small fault has offset this rock with apparent left-lateral motion. You can see small drag folds in the finer laminae on the left side of the photo, a feature which is noticeably absent from the courser laminae. This demonstrates a rheological difference between course and fine laminae where fine bands are relatively softer compared to the course bands. The course grains are composed of neocrystallized dolomite, magnetite, and quartz.

Click here to see the picture on Instagram

Have an instagram? Follow me here. You’ll get a preview of the rocks, more field photos, plus more random photos I take.

Want more Friday rock pictures? Check out Callan Bentley’s Friday Fold series.

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Geoconvention 2012 Vision: Day 1

I’ve been in Calgary, Alberta first for a short course on sequence stratigraphy and now for the conference Geoconvention 2012: Vision. After finally finding the badge pick up booth, I started circling interesting talks.

I ended up spending the first half of the morning in the session titled Carbonates from Canada and Abroad. Hans G. Machel discussed the karsts of Barbados including natural oil seep pools at the surface. The talk was very exciting and included amazing photographs of caves and sea stacks. A masters student mapped 2830 sinkholes. The age of the rocks? Less than 1 million years. That’s some fast processing.

For the afternoon I sat in on Structure and Tectonic Styles of Fold and Thrust Belts – Dr. Eric W. Mountjoy Honorary Session. This session was amazing. It highlighted the amazing work and life of Eric Mountjoy, who produced a map of Jasper Park’s Miette area, and studied the area for much of his life. Many of the speakers in the session were former students of his and their talks centered on the research they did under him. This session was particularly interesting to me as I am studying thrust faults in a nappe complex and had just visited the Canadian Rockies (Banff)for the first time over the weekend. Here are the presentation topics for those interested in learning about them:

Raymond A. Price presented on the Cordilleran Foreland Thrust-and-Fold Belt in southern Canada
Daniel Lebel presented on Transfer zones.
Stephen E. Grasby discussed the Development of the Selwyn Range Shear Zone in Relation to Middle Miette Facies Change
Normand Begin discussed fieldwork in a landmine area and the Influence of Pre-existing Extensional Faulting and Foredeep Basin Geometry.
Margot McMechan presented on Structural Style and Kinematic Evolution of the Central Rockie Mountain Foothills.

Looking forward to tomorrow. I have yet to pick out which talks I will be attending…

Drop everything and manipulate your stereonet data in 3D

Stop what you’re doing. Stereonet software now displays data in 3D, let’s you rotate, go crazy.

Geologists, get excited.

Anyone who has worked with stereonets by hand knows that in addition to being an invaluable structural geology tool, they are also a pain, especially for large data sets.

For the unfamiliar, stereonets are circular graphs that are used to represent 3-dimensional data in 2-dimensions.  Data can be everything from bedding measurements, fault orientation, to cleavage planes in a fold. Once this data is plotted on the stereonet it can be manipulated to work out everything from the deformation history of a region to the correct orientation to drill a mineralization zone (ie. where’s the gold at?).

Figure 1: Some bedding plane and lineaion data displayed on a 2D stereonet in OSXStereonet.

Stereonets are notoriously difficult for students to grasp on the first try around. My undergrad (UCSC) structure class used a hamster ball-cd set up to explain 3D bedding plane orientation projected into 2D. That was okay, but also a bit funky. Doing stereonets by hand can be even more funky. Enter stereonet software.

The most widely used free stereonet software (this is from a poll/guess on what people I know use) is Rick Allmendinger and Nestor Cardozo’s OSXStereonet (mac) and Stereonet7 (windows). I haven’t used the mac version much, but from what I’ve seen it is always about 1 version iteration ahead its windows counterpart.

Figure 2: Same data as Figure 1 displayed in 3D, rotated with North pointing top-right. Awesome.

The mac version made a huge leap recently with the introduction of a 3D viewer. Like, hell yea! This feature is so awesome, it blew my face off when I first loaded it up. The stereonet can be rotated to view the data from any angle. I think this could be a great teaching tool to help students grasp what a 2D stereonet is really displaying. Of course they should finish the assignment by hand to be sure that they really grasp the concepts and are not just entering data into a table 😀 .

My first thought when I saw this (after HOLY SHIT THIS IS AWESOME!) was how cool this would be to combine with the KeckCaves software and a 3DTV. It would be SO cool to visualize the stereonet in “real” 3D and manipulate it with a Keck wand.

Also, the stereonet .pdf files it exports look very clean, which is an improvement from previous versions.

And for those who are wonder… no I’m not writing this on a mac, I am running the program in a VirtualBox OSX system.