Summer is in full swing and this summer is all about lab work. An undergraduate researcher and I are in the midst of extracting the terrigenous (land-derived) sediment from marine sediment. We are interested in the grain-size and compositional characteristics of the terrigenous component to better understand the history of a long-lived oceanic current that transported the sediment. Isolating the terrigenous material means we have to get rid of the other components, namely the biogenic (marine microfossils made of carbonate and opal) and authigenic (metalliferous oxyhydroxides that formed in place) material. We are using this method with some tweaks from a helpful collaborator.
I have >1,000 samples from IODP Expedition 342 (see this post for more about that expedition) that will eventually be processed in this way. But, because we have not done this before and are still getting the lab fully equipped, we are currently using ‘practice’ sediment (a chunk from one of the core catchers) to fine-tune the methodology. That is, when we make a mistake — which is inevitable when learning something new — we won’t be sacrificing a ‘real’ sample. This training will pay off in a couple weeks as we ramp up and start processing samples in batches.
While we work on that two of my graduate students are busy crushing, grinding, sawing, drilling, etc. rock samples for their respective Ph.D. projects. We’ve got mineral separation underway for bedrock thermochronology, sample preparation for stable isotope measurement of carbonate rocks, and thin sections being made.
Here’s a shot of the sand dunes not far from Stovepipe Wells in Death Valley National Park from this past March. Check out this Flickr set for a whole bunch more. Happy Friday!
This week’s photo is from the deck of the JOIDES Resolution drill ship last summer. Before IODP Expedition 342 I had spent only a few days at sea, and even then it wasn’t more than ~20-30 km from land. Being out in the open ocean — several hundred km from land — was an experience I didn’t think about or appreciate before I did it.
I never grew tired of watching the sea during that two months. The interaction of swells of different sizes and forms moving in different directions resulted in unique displays of nature. And it’s quite different than watching the sea near the coast. Watching the water pile up into ‘mountains’ and ‘ridges’, creating a constantly changing topography, was actually quite therapeutic during an incredibly busy expedition.
See this photo and many more from IODP Expedition 342 on my Flickr page.
I just had to share this image that Commander Chris Hadfield, an astronaut currently on the International Space Station, posted yesterday. I really like this perspective of the Mississippi River delta. It’s nice to get a view that isn’t a standard map (north to the top and looking straight down). This slightly oblique view emphasizes how ‘delicate’ the bird’s foot part of the delta is, that the boundary between what is land and what is not is a bit blurred.
I’ll also use this post as a plug for Commander Hadfield’s Twitter feed. It’s really quite simple — he takes photos of the Earth out the window of the space station and shares them. There isn’t a link to some busy web page or other social media noise, just a beautiful photo of our planet. And he does several each day. Simple and awesome.
This week’s photo is from Panamint Valley in southeastern California (the valley to the west of Death Valley). This example of a stretched-pebble conglomerate is actually a boulder in a wash and not in place. Therefore, I’m not exactly sure of it’s age, but it’s likely from the Proterzoic Kingston Peak Formation, which crops out in the Panamint range. It’s pretty awesome to think about pebbles in a conglomerate getting deformed and stretched like this.
This is my first time attending an EGU (European Geosciences Union) meeting and it’s been great. It’s a rather short trip for the distance traveled — just three nights here in Vienna, Austria — but it has been worth it. The meeting reminds me of the annual AGU meeting held every December in San Francisco, although a bit smaller.
My main motivation for traveling all this way was to give an invited talk in a session convened by Alex Whittaker, Sebastien Castelltort, and Philip Allen called Tectonics, Sedimentation, and Surface Processes yesterday morning. Jon Tennant (@protohedgehog) of the EGU blog Green Tea and Velociraptors took this photo of me (above) beginning my talk.
This talk discussed some new research a close collaborator and good friend of mine is doing comparing crystallization age (U-Pb) and cooling age ([U-Th]/He) of detrital zircons from Magallanes foreland basin (southern Chile/Argentina) sedimentary rocks. Constraining the crystallization age and cooling age of a single zircon grain provides valuable information about the sediment source area, timing of exhumation (when that mineral grain became a sedimentary particle, roughly), and whether or not the grain experienced additional heating through burial.
For this session we used these new data to highlight the recycling of sediments over ~50 million years of fold-thrust belt and foreland basin evolution. The occurrence of recycling of material in such systems has been known for decades, but these newer geo-/thermochronologic techniques can be used to determine the timing/duration of these processes more accurately. For this talk, I discussed these new data within the context of reconstructing ancient sediment-routing (or, source-to-sink) systems. For example, how might recycling of older foreland basin deposits influence our ability to use general grain-size trends to better understand system morphology (e.g., Whittaker et al., 2011)? In the spirit of sharing new ideas and preliminary results I posed more questions than answers in the talk — with the hopes of initiating discussion. I got some great feedback from people throughout the day and ended up having numerous conversations with others doing similar work. This is the whole point of conferences and makes the trip worth it.
My other motivation for attending EGU was to interact with researchers whose work I’ve been following but had not actually met in person yet. It’s great to put faces to names and to get to know people beyond their published papers.
Last month I traveled to Bremen, Germany along with the rest of the IODP Expedition 342 scientists to help sample the sediment cores we acquired from the bottom of the North Atlantic Ocean last summer. As I mentioned in a post a few weeks ago, the sampling of these archives is a key step for the expedition goals.
The video above (~8 minutes long) does a great job explaining this stage of the science. If the embedded video is not showing up go to this page: http://www.youtube.com/watch?v=J0r2u5xdS7E&feature=youtu.be