“HOW LONG HAVE YOU BEEN DATING?”

In my post about new evidence for the supercontinent Rodinia, I mentioned that there’s an interesting process that’s performed for dating rocks and that it’s actually the kind of work that I assist with. I thought it would be interesting to make a post that goes into more detail about how this is done.

I’ve made a presentation that outlines the science and process behind dating rocks which should help introduce the subject matter in a way that’s quick and easy to digest. Here’s the link: https://prezi.com/3k4tv3lligxw/geochonology-and-mineral-separation/

To summarize the material in the presentation, zircon is a mineral that is in virtually every kind of rock and contains uranium impurities. Uranium decays radioactively at a very slow rate. This means we can calculate the amount of radioactive decay that has occurred within the zircon and use that to come up with a formation age for the rock.

There are four main processes that we must go through in order to separate the zircons from the rock: crushing, panning, demagnetizing, and heavy liquids. I decided to make a video showing my favorite, heavy liquids. This process involves putting the sample in a super dense liquid (methylene iodide/MEI) and extracting the densest minerals, which should all be zircon. This is the most rewarding stage of the process because I get to finally see all the zircons I’ve been working to isolate. The video shows off the process and the logistics of how it’s performed in detail. Check it out below:

The sample used in the video was representative of a really high zircon yield. This was great because it was easy to see the large quantity of them sinking during the time lapse and collected in the filter paper at the end. In samples that have a lower yield, the zircons may be harder to see sinking in the MEI and collected in the filter paper. Ultimately the zircon yield in a sample simply depends on the type of rock the sample is and where it came from, I just got lucky by picking one that had a high yield for the video.

Geochronology is really helpful for solidifying geologists’ understanding of specific sets of rocks. Without this method we wouldn’t be able to come up with an exact age for any given set of rocks. These qualitative ages allow geologists to improve their understanding of a region, how it formed, and what it has experienced in the time since it formed. USGS is currently working on dating a large number of samples from various sandstones near the Mississippi River delta. They send out field geologists to collect samples that they want dates for. These samples are then sent to UC Santa Barbara where I take them through the processes of mineral separation. Finally I send the zircons off to our laser lab where they can be dated. While this project is obviously still in its earlier stages, when it is complete it should provide significant data that improves our understanding of that region.

BLACK GOLD COMES AT A DESTRUCTIVE PRICE

A short article posted on February 19th by USGS describes some of the dangers of hydraulic fracturing, more commonly referred to as fracking. Fracking is a technique of oil drilling that has recently become simultaneously popular and infamous due to its potential environmental concerns.

It might be helpful to provide some background on the process of fracking. Conventional drilling is possible by tapping into an oil source underground that is simply contained by surrounding rock. There’s certain kinds of rocks that contain oil but can’t be drilled conventionally. This is because the oil is essentially inside the rock. We have to drill laterally into the stratum (layer of rock) in order to get oil out from the inside of rocks. Then the drill is taken out and a solution of water, chemicals, and sand is forced into the hole, fracturing the rock containing oil. That’s where the term fracking comes from! Once the solution goes into the rock, the oil can be extracted and the sand fills the cracks. Although it wasn’t the focus of the article, one of the main environmental concerns is that remnants of the chemicals that are pumped in can contaminate the water table.

The concern fracking poses that the article focused on was induced seismicity. This means that something goes wrong in the process, causing an earthquake. This is likely caused by the sand not filling enough of the fractures. While these earthquakes are rarely large, they can be damaging because they occur in areas that do not generally have earthquakes. Fracking is done in places like Oklahoma which doesn’t usually have earthquakes, but there have been a number of cases of induced earthquakes. These earthquakes may have been relatively small, but because the area’s buildings are not earthquake proof they have caused some damage.

In California the main concern is not with induced seismicity because our buildings are much more resistant to earthquakes, but a greater concern is with the chemicals that are pumped into the fractures. There have been a few to many oil spills in the area to make most people comfortable with this kind of thing, so a lot of environmentalists aren’t to keen on fracking.

The article wasn’t particularly conclusive about the potential solutions for this problem, only that they are being addressed. While fracking has enabled us to exploit previously unobtainable oil, it may be too destructive to be worth it until it’s perfected.

Source: http://www.usgs.gov/newsroom/article.asp?ID=4132&from=rss_home#.VOwZWPnF-So

SUPERCONTINENTS AND THEIR SUPERCYLES

An article published in national geographic in August of 2011 revealed that Texas and Antarctica were once connected. Many people have heard of the ancient supercontinent Pangaea, but Earth scientists have found evidence that there is actually a cycle the continents go through in which they are separated and reunited again. This cycle can take up to half a billion years, but with a planet that’s over four and a half billion years old, we have to deduce that there have been multiple supercontinents throughout the planet’s history.

Here’s a diagram of what geologists believe Rodinia looked like.

Just as there is plenty of evidence for the existence of Pangaea (mostly in old mountain ranges) there has been some recent evidence to support the hypothesis of a supercontinent prior to Pangaea called Rodinia. You may be asking yourself, “What could make them think the continents could be in a certain orientation over a billion years ago? How do they figure this kind of thing out?” Well there’s a lot to it, but basically they make a lot of observations of rocks in the field, and they take samples back to the lab to run tests on them.

They took samples from the Franklin Mountains in southern Texas and samples from Coats Land in Antarctica and performed radioactive age dating on them. There is an interesting and cool process for dating rocks (it’s actually what I assist with in the lab!) but it can’t really be explained simply without a post of its own. In short, rocks can be dated according to the amount of radioactive isotopes in them. As it would turn out, the rocks from Antarctica and Texas came up with the same date. This means they formed (in this case erupted volcanically) at the same time, indicating the range of volcanoes formed when the two continents were in contact with each other. This kind of thing is always exciting for those who are doing research on it, but there is always more to be done. What other locations might be good to support the hypothesis of Rodinia? How might this data sharpen our understanding of the supercontinent cycle hypothesis?

The Franklin Mountains of Texas (top) and Coats Land Mountains of Antarctica (bottom).

Source: http://news.nationalgeographic.com/news/2011/08/110815-texas-antarcica-connected-supercontinent-rodinia-science/

SUSTAINABLE WAYS TO GET UNSALTY

After my post about the United States’ groundwater contamination, I thought it might be interesting to look into what kind of new research is going into filtering saltwater to be drinkable. As it turns out, an article was published this year in National Geographic about the progress we’ve made in water desalination (the process of making seawater drinkable) and the issues it still poses. The most significant issue is not that we don’t have the technology to make saltwater drinkable, but it comes at a high energy cost. The article mentions four locations across the world that are experimenting with renewable energy like wind and solar to fuel their water desalination plants.

The United Arab Emirates plan on using solar power for their new plants. If they set up one square kilometer of solar panels the region’s yearly solar energy intake would be equivalent to burning two million barrels of oil! While a square kilometer of solar panels may seem like a lot, they could be spread out between multiple desalination plants considering that amount of energy is more than enough to fuel all of them.

Australia is planning on going solar for their desalination plants as well. They are getting some assistance from a company which already provides the country a significant service. This corporation is paying for the solar panels because they need to utilize filtered seawater to grow crops. This is done using greenhouses across Australia. Lots of Australia is not particularly conducive to agriculture with dry soil and air, so they need these greenhouses to grow produce.

For those who like diagrams, this is a good explanation of how one of the Australian plants works. Texas is another location in need of a more reliable fuel source for their plants after their record breaking drought in 2011. The use of these plants since then has been costly because they’re fueled by coal and natural gas which are not only unsustainable, but also require water to be used as a cooling agent for the desalination process. They have the most wind power installations in the country, but they’re considering using solar in addition to wind to power the plants because solar is more reliable than wind.

California is the last location mentioned in the article and the idea for its new plant in San Diego is the most innovative, and honestly just really cool. Additionally, this water may be essential for us Californians who are going through such a brutal drought. Instead of using solar panels, this plant will use mirrors that can reflect 100% of the sun’s energy into heat. This heat is then used to distill the seawater. This means that the process avoids using membranes which require constant energy input. While this seems to be the best solution, it requires more money and research before it can be utilized. In any case, it’s gneiss to hear about advancements that can help with both the energy problem and the water problem.

Here’s an overhead view of what the San Diego plant will look like when it’s done.

Source: http://news.nationalgeographic.com/news/energy/2015/02/150202-energy-news-renewable-salt-water-drought/

WHAT’S IN OUR WATER AND WHY

Don’t take that fresh drinking water for granite! An article published on January 21^st of this year revealed that after two decades of extensive research conducted by USGS (the United States Geological Survey), the national summary report of the nation’s groundwater was just completed. The objective of this study was to gain understanding of the possible ways groundwater can be contaminated across the country, causes for this contamination, and how it could lead to potentially harmful effects for the people that drink it.

Over a third of the country’s population depends on groundwater as a source for drinking water in virtually every region of the nation, making this study equally important for those who depend on groundwater and those who study it. If the study sounds like it took a long time, it’s because they examined a ton of wells, approximately 6,600, in all fifty states! That’s a lot of water to run tests on. In any case they managed to find something wrong with the water in some way in almost every single region. To my surprise, the vast majority of them have a higher percentage of natural contaminants than human induced contaminants. The important portion of this factoid is why each region is contaminated rather than what is actually in the water. After all, it’s equally bad if the water contains arsenic (a naturally occurring water contaminant) or if it contains human induced contaminants like pesticides.

Here’s a nice graphic of the results from the study that was in the article.

In general, their findings concluded that the groundwater contamination was caused by humans regardless of whether or not the contaminant was naturally occurring. This obviously requires some explaining. There are naturally occurring compounds in the Earth’s crust that can contaminate the water table (essentially the region that groundwater exists within), but they may not actually come into contact with the water unless it is tampered with. This happens when humans drill into the water table in order to extract groundwater; the water is pulled through regions that it might not have come into contact with otherwise. Therefore, even if the water is contaminated with a compound that occurs naturally in the Earth the contamination itself was caused by people extracting the water. The lingering question remains of how to solve this problem. Maybe we should start investing more in salt water filtration? Maybe hydrologists need even more data before they can come up with a resolution. Maybe we should even start putting more money into researching ways to filter out these contaminants. In any case it’s an interesting new set of data that will continue to expand in the coming years.

Source: http://www.usgs.gov/blogs/features/usgs_top_story/the-quality-of-the-nations-groundwater/?from=title

LASERS! MAPS! NEW MAPS MADE BY LASERS!

Keep mapping, keep rocking! An article was published in November of 2013 by the US geological survey concerning their new advancements in topographic mapping. Topographic maps are primarily displays of elevation changes along with some other descriptive information. The article provides interesting data and insight into their methods for crafting these detailed and awesome maps. One of the new advancements is the expansion of digital topographic maps in Alaska. There’s now over four hundred detailed topographic maps of regions all over Alaska that were previously either unmapped or the maps were outdated. This project is far from over though, at its end in a few years there will be over 11,000 comprehensive free-to-access maps of Alaska! That’s more data than most geologists will ever need, but more data is always far better than less.

The article also highlights some new tech being used in the field to map the damage caused by hurricane Sandy. This new method is referred to as lidar (light detection and ranging), and it’s able to take measurements of laser refraction off topography and create a high res map from it. Lidar is able to give the most precise and thorough representation of true topography than any other method that’s been used in the past. Unfortunately it’s really expensive and takes time. I’m actually going to be using some lidar maps during my spring break field trip to the Mojave, so I’ll be lucky enough to actually work with maps with this level of detail. Anyway, there are plans for the next eight years to collect and analyze lidar data from even more places across the country, providing some very useful (and cool) topo maps. The latter half of the article provides some less interesting information about some new map collections (mostly old/historical map compilations) that USGS is working on making, presumably for the sake of maintaining historical documents and to show how far we’ve come in the art of topographic mapping.

Here’s an example of a topographic map of Mount Hood obtained using lidar.

Source: http://www.usgs.gov/blogs/features/usgs_top_story/putting-the-planet-on-the-map/