Matt Herod

The Accretionary Wedge #60 – Call for Posts – Momentous Discoveries in Geology

Matt Herod September 1, 2013

I am lucky enough to play host to the 60th edition of the Accretionary Wedge. First, I’d just like to highlight the fact that there have been 60 previous and excellent wedges and ! WOW. This has to be one of the best blog carnivals out there, and here is to another 60 great AW’s in the future.

There are lots of sayings out there about how science is a journey with many steps and paths or a giant building made of many small blocks that contribute to the enormity of an entire field. All of these cliches are pretty much pointing out the same thing. Namely, that the knowledge base in each field is composed of the work of thousands of people all contributing a little bit and slowly building an understanding of the natural world. This is very true, however, some of these contributions are bigger than others, and geology is no exception. Over the history of geology there have been many major discoveries that advanced the science, from the original work of Hutton, Lyell, Steno and Darwin, to more modern revelations. Each discovery has in some way altered our perception of how the Earth works and either opened new avenues of research or provided previously unknown constraints and laws. Therefore, for this wedge the topic will be momentous discoveries in geology or its sub-disciplines that you feel have altered or shaped our understanding of how the Earth works, or opened new doors into research that had never been considered before. The discovery you choose does not have to be universally recognized as momentous but should be in your opinion. It could be something that we take for granted every day, but is in actuality part of the underpinnings of our science.

A tool that changed the world. The telescope of Galileo. I just saw it in Florence along with his middle finger!

The due date for this wedge will be on September 30 and, as usual, add a link to your post in the comments below. I’ll then compile them into a summary post.

Happy discovering,

Matt

Day 3 and 4 – Craters, Very Old Rocks, Fukushima and Extinctions

Matt Herod August 30, 2013

Here is my Goldschmidt summary part 3 comprising both day 3 and day 4. I had to prepare my own talk, that I gave on Thursday (day 4) so I had to put the blog on hold to practice.

Here are a few of the most interesting talks that I went to:

Fred Jourdan hailing all the way from Curtin University in South Australia gave a talk called – Volcanoes, asteroid impacts and mass extinctions (abstract). In his funny and very interesting talk Dr. Jourdan asked the question what is responsible for mass extinctions in geologic history? There has always been considerable debate in the scientific community about what caused all of the mass extinctions that have taken place over geologic time. Was it the volcanoes or the meteorite impacts? Dr. Jourdan compared the dates mass extinctions and tied these to the dates of volcanic eruptions and meteorite impacts to see if any two or three occurred at the same time. He found that volcanic eruptions coincided with mass extinctions better than meteorite impacts and concluded that volcanoes have played a dominant role in mass extinctions throughout Earth history. However, meteorite impact dating needs to improve since they also play some role.

Dr. Phillippe Van Cappellen from the University of Waterloo gave a fantastic keynote address (abstract) on the mysterious part of the groundwater world called the hyporheic zone. The hyporheic zone is the magical place in a stream bed where groundwater flows into the stream. Sounds pretty simple right? According to Dr. Van Cappellen, wrong! Very wrong. It turns out that the hyporheic zone is extremely complicated and can have major impacts on the flow of chemicals from groundwater into surface water. Imagine this scenario: a local aquifer is contaminated with PCB’s. This is bad, but they have not made it into the nearby stream yet, so we only have to remediate groundwater. However, these chemicals will get stored or released by the hyporheic zone and could potentially contaminate a larger area than we thought. Dr. Van Cappellen’s work aims to understand how the h-zone functions under different chemical conditions and what sort of environmental factors such as water level, organic content or freeze-thaw cycles can affect it.

John O’Neill a new professor from uOttawa gave a terrific talk called Earth’s Hadean Crust: Insights from the Nuvvuagittuq Greenstone Belt about some really, really, really old rocks (abstract). In fact he has dated some rocks located in Northern Quebec at 4.4 billion years old!!!! The Earth is only 4.6 billion years old so these rocks have been around right since the beginning. John’s talk was very well attended and he presented some very interesting results to prove that these rocks are so old. This is still a very controversial topic and I am sure that discussions will continue for quite a while.

The next talk was very interesting to me. Dr. Yasuyuki Muramatsu, one of the leaders in the field of radio-iodine research, presented his talk right before mine. His talk was called: Reconstruction of the Accident-Derived I-131 Deposition in Fukushima Through the Analysis of I-129 in Soil (abstract). A lot of iodine-131 was released from Fukushima, which as a short half life of 8 days. This meant that it was very difficult for researchers to map its fallout over Japan, which is essential. However, using iodine-129 as a proxy for iodine-131 is possible and Muramatu’s group set out to do just that and they produced some really nice maps showing the fallout pattern of iodine in Japan.

So that is it for Day 3 and 4. Instead of doing a Day 5 summary I am going to try and do an interview with someone and cover their research in a bit more detail. So stay tuned for that!

Cheers,

Matt

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Goldschmidt 2013 – Day 2 – Carbon, Uranium, Litigation and London

Matt Herod August 28, 2013

Day 2 of Goldschmidt 2013 is done and what a great day it was. Hectic, but conferences always are. There is just so much to see and do, so many people to talk to and so many people to meet for the first time that it can be a bit overwhelming. The best thing to do is grab a coffee, and dive right in.

My first talk of the day was by J. Schmitt and was called CF4 and CO2 – Coupling Weathering and Carbon Cycle. This very interesting talk introduced me to a new gas that can be used as proxy for weathering over time: CF4. CF4, it turns out, comes from fluorite that is contained in very small quantities in granite. When glaciers scrape the top off a granite outcrop they expose this fluorite and it weathers to release CF4. The CF4 then hangs out in the atmosphere for 50-400 thousand years. It eventually gets trapped in ice cores and can then be used to calculate long term weathering rates.

One thing that everyone does a conferences like Goldschmidt is support their colleagues from home. With this in mind the next talk I attended was by Mike Power from uOttawa. Mike gave a great talk on exploration geochemistry and how we can use noble gases and metals in soil to look for deeply buried uranium deposits. I won’t go into more detail here. If you want to read about Mike’s work check out the guest post he did for me a few months ago.

Once Mike finished his talk I went to support another familiar face. Not that he needs it since his talk was standing room only. I speak of Dr. Kurt Kyser who hails from my beloved alma mater Queens University at Kingston. Kurt was speaking about the importance of geochemistry to our lifestyles (abstract). Amazingly, Kurt stated that in our lifetimes we each use approximately 2 million kilograms!! of metal, mineral and fuel resources. In order to sustain this quality of life we are always searching for new mineral deposits that can provide us with these things. However, most of the easily obtainable ores deposits have already been obtained. This leaves us with the problem of finding new deposits that are not so easy to discover. Kurt gave a great overview of the techniques we can use to do this, such as sampling unusual things like tree sap or leaves to find deposits. He also made the point that a good geochemical characterization of ore deposits makes remediation much easier when it is time to close the mine and reclaim the land. Yeah Queens!!

The next talk was an interesting look at the source of iodine and chromium in the Atacama desert. It was given by A. Perez-Fodich and was called The role of groundwater in the formation of the giant nitrate deposits of Atacama: Iodine-129 and stable chromium isotopic evidence (abstract). The Atacama desert is one of the dryest places on Earth and is home to some very unusual mineral deposits. Indeed, it is one of the only places on Earth where minable quantities of iodine can be found. The iodine is found in huge nitrate deposits and is likely coming from weathering of nearby ocean sediments. It is then transported by groundwater to the desert where the water evaporates leaving the iodine behind.

The next talk I am going to highlight really galvanized me. I intend to write a full post about this once I get a chance to do some more research. The speaker was Luigi Marini and the talk was called How to Protect Geochemists Working on Environmental Issues from Litigation? (abstract). The talk covered an ongoing Italian court case in which several geochemists from the University of Siena have been sued after publishing results stating that they could not find above background levels of depleted uranium and former Italian military firing ranges. These results infuriated the public which felt that some sort of cover-up was occurring and a local prosecutor initiated litigation against the researchers. This incident has strong shades of the L’Aquila earthquake verdict and therefore it is crucial that strong technical advice is provided by the scientific community to ensure the no miscarriage of justice like that of L’Aquila can happen in this case.

John Ludden, Director of the British Geological Survey, gave a great closing talk in the Importance of Geochemistry session entitled the Geochemistry of London (abstract). At first, I wasn’t sure what to expect. I mean, what geochemistry is there in a city. Wow, was I ever wrong. John introduced the projects that the BGS and partners have going on to monitor and understand pollution in London. This is massive undertaking and they have actually mapped the geochemical distribution of many contaminants on a street by street resolution for the entire city as well as numerous analyses of the water and sediment in the Thames. The most interesting points were the numerous indications of pollution from the past still present in soil and sediment. Indeed, the Thames had very high PAH levels that were left over from the coal burning era and leaded gasoline er, petrol left its mark on London soils. Incredibly, there was one place, the site of a former manufacturing plant, that had such high nickel it could be considered valuable ore material by today’s standards.

Stay tuned for Day 3!

Cheers,

Matt

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Goldschmidt2013 – Day 1 (Monday)

Matt Herod August 27, 2013

Wow! I have finally arrived at Goldschmidt 2013 and it is so, so great to be here! Day 1 was already a whirlwind. Unfortunately, I missed the icebreaker last night and arrived a bit late this morning due to scheduling conflicts so I missed a few talks, but I am here now and ready to listen, learn, discuss and blog!

Talks I went to today:

Sadly, I missed the first talk I wanted to see. My friend, Erin, from uOttawa presented her research at 9:30, while I was still in the Florence airport so I missed out on that one. Her work is titled Fluid Evolution Recorded by Alteration Minerals along the P2 Reverse Fault and Associated with the McArthur River U-Deposit and the abstract can be viewed here. Basically, water running along a fault making all sorts of strange minerals and carrying lots of radioactive goodness.

So the first talk that I actually watched was by Mitch Kerr from Saint Mary’s University and was entitled Preliminary Evaluation of Trace Hydrocarbon Speciation and Abundance as an Exploration Tool for Footwall-Style Sulfide Ore, Sudbury Igneous Complex, Ontario, Canada (abstract). The talk raised some fascinating points about using the occurrence of light, thermogenic hydrocarbons as a possible took for exploration of platinum group elements in the Sudbury Impact Crater. Indeed, the results showing the different types of light hydrocarbons and their relationship to ore bearing zones was very promising.

Next was a talk by Wooyong Um from Pacific Northwest National Lab about Limited releases of U and Tc from Hanford tank residual wastes (abstract). The talk explored how to safely close radioactive waste storage tanks located at the Hanford site. The waste will be moved to a long term repository, but some sludge will remain on the bottom that contains high concentrations of uranium and technetium. This talk compared the efficacy of three methods for immobilizing the U and Tc that remains in the tanks by creating minerals that will bind the U and Tc and make it unavailable to groundwater leaching. The authors found that all three techniqies they attempted were successful and preventing leaching of U and Tc. So a good news story all around!

I then speed walked over to another session where keynote speaker M.O. Andreae from the Max Plank Institute was asking if any answers were blowing in the wind. Seriously though he was Can Saharan dust explain extensive clay deposits in the Amazon Basin? Radiogenic isotopes as tracers of transatlantic transport (abstract). He attempted to answer this question using a number of isotopic and geochemical methods. He used total geochemistry, lead, strontium and neodymium isotopes to show that unambiguously the Amazon clay does not come from Saharan dust despite visual evidence showing it across the Atlantic. Indeed, the source of the Amazon clay deposits turned out to be the high rate of weathering of the bedrock due to the humid conditions. However, Dr. Andreae also found that the despite the fact the clay is not from the Sahara a substantial amount of the nutrient potassium is transported to the Amazon from the Sahara. Very cool!

The last talk for me but not least was by fellow Canadian Chris Weisener from the Unversity of Windsor. His talk: Bacterial Mineral-Metaloid Redox Transformations in Anaerobic Environments (abstract) covered how bacteria can influence the uptake of heavy metals into the mineral jarosite, which is found in many low pH, iron/suplhur rich environments. Indeed, almost all mine drainage sites have jarosite. Chris showed that metals such as selenium can actually be incorporated into the jarosite mineral structure by bacteria which reduce them for food and in doing so make these metals available for incorporation.

I followed this up with a quick visit to the Goldschmidt press conference to hear about the work of Victor Sharygin of the Institute of Geology and Mineralogy in Novosibirsk, Russia. Dr. Sharygin talked about how the Chelyabinsk meteorite may have had a brush with the Sun before falling to Earth because it shows signs of having been melted prior to colliding with Earth. Furthermore, the meteorite also contained some very interesting and unusual mineralogy and mineral morphology such as sceptors made of platinum, osmium and iridium in the fusion crust of the meteorite. This press release has already picked up some international coverage and more complete articles can be found here.

Thanks for reading. I am excited for what great discoveries Day 2 will hold.

Cheers,

Matt

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