For the LASI V workshop which I attended a couple of weeks ago, the Physics of Geological Processes (a scientific Center of Excellence in Norway and one of the workshop sponsors) offered two scholarships for South African geology students to attend the workshop. I thought I would introduce you to the two wonderful scholarship awardees here on Georneys. Both of the scholarship awardees are studying for their masters degrees in geology with Prof. Gary Stevens at Stellenbosch University, which is one of the top universities in South Africa. Both students presented their masters degree projects at the conference.
Priscilla in the field at LASI V.
The first scholarship awardee is Priscilla Ramphaka, who comes from the Limpopo Province of South Africa. At LASI V Priscilla presented a talk titled, “The origin of rhythmic magmatic layering in the S-type Peninsula Pluton, Cape Granite Suite, South Africa.”
Prsicilla explains, “I presented my project on the layering in the granites found at Llandudno in Cape Town. My goal was to find out how the layering formed at Llandundo since that is not well understood.”
Priscilla says that she loved everything about the LASI V workshop, from the presentations to the field trip to the meeting of new people. Overall, she says that she really enjoyed participating in her first international geology conference. In addition to being a talented geologist, Priscilla is also a talented linguist– she speaks an impressive 10 languages!
Cedric in the field at LASI V.
The second scholarship awardee is Cedric Joseph, who comes from Windhoek, Namibia. At LASI V Cedric presented a talk titled, “The petrogenesis of the ignimbrites and quartz porphyritic granites exposed along the Saldhana west coast, South Africa.”
Cedric explains, “I did a project on the ignimbrites and subvolcanic rocks that you find around Saldhana. We investigated the petrogenesis of the rocks as well as the rock textures because it’s quite a controversial issue whether these rocks are intrusive or extrusive.”
Cedric says that his favorite part of the LASI V workshop was learning more about sills and dykes, particularly through observing these features in the field. Cedric is looking forward to working for a mining company in Namibia starting next year.
I really enjoyed meeting both Priscilla and Cedric at LASI V. I hope to run into them again, especially since Stellenbosch is just down the road from where I live in Cape Town.
Well, I did it again. I forgot to post my Monday Geology Picture on Monday. Sorry about that! I had a long, busy day at work. After work, my husband and I went to see a movie with some friends and only arrived home fairly late.
This week, I thought I would share a picture of some old mining posters which I saw on an underground mine tour (of an inactive mine) at a place called Gold Reef City in Johannesburg, South Africa. At Gold Reef City the area surrounding an abandoned gold mine has been turned into a gold mining themed amusement park. Part of the old gold mine has been preserved for tours, and several of the park attractions are about the history of gold mining in Johannesburg. If you ever find yourself in Johannesburg, I highly recommend a visit to Gold Reef City. The history is very interesting, and the rollercoasters and other rides are pretty fun, too!
Here’s a closer view of the mining posters:
A closer view of the old mining posters at Gold Reef City.
Some of the mining posters are written in an interesting pidgin language called Fanagalo, which is a mixture of primarily Zulu, English, and Afrikaans and has been used for many years as a lingua franca among mineworkers in South Africa and, to a lesser extent, in other southern African countries. In recent years, English has been replacing Fanagalo as a lingua franca in the mines, but there are still some mineworkers who speak Fanagalo. The mining posters likely date from the 1960s and 1970s and advocate safety in the mine.
A bunch of grapes which I purchased earlier today at the Woolworth's grocery store across the street.
def. Botryoidal:
Shaped like a bunch of grapes.
The word botryoidal comes from the Greek word “botrus”, which literally means a cluster or bunch of grapes. In geology the word botryoidal is often used to describe a rock texture or mineral habit (appearance).
Here are a few pictures of some botyroidal rocks and minerals:
Botryoidal chalcedony. Picture courtesy of Patrick Donohue.Botryoidal arsenic. Picture courtesy of Patrick Donohue.Botryoidal carbonate. Picture courtesy of Patrick Donohue.Botryoidal vapor-phase altered rhyolite. Picture courtesy of Lockwood DeWitt.Botryoidal ferromanganese crust dredged from the Ninetyeast Ridge, Indian Ocean, Summer 2007.More botryoidal ferromanganese crust dredged from the Ninetyeast Ridge, Indian Ocean, Summer 2007.Botryoidal (and purple!) carbonate from the Samail Ophiolite, Sultanate of Oman.A geologist, a botrus, and a botryoidal rock.
***Thanks to Patrick Donohue for suggesting this week’s word and to Patrick and Lockwood DeWitt for providing pictures.***
LASI founder Christoph Breitkreuz checks out a dolerite sill in the field in the Karoo on the LASI V field trip.
Last week I had the great honor and pleasure to attend the LASI V workshop, which was held in Port Elizabeth, South Africa with a field trip to observe sills and dykes which were emplaced into the Karoo sedimentary basin. I was kindly invited to attend LASI V by organizers Henrik Svensen and Sverre Planke, who are both scientists at Physics of Geological Processes, a Center for Excellence in Norway. I was invited to attend LASI V to observe, learn a little about subvolcanic systems, and write some blog posts about the workshop here at Georneys. Over the next few weeks, you’ll see several posts about the LASI V workshop. I plan to write about some of the workshop participants and their research on subvolcanic systems. I also plan to write about the Karoo field trip. I’m sure that I will also have quite a few LASI themed “…in Pictures” posts. I thought I would start off with a basic post to explain what LASI is all about. This is a question and answer style post. Many of the answers are based on interviews I conducted with Christoph Breitkreuz, a professor at TU Freiberg in Germany and one of the founders of LASI, and with Sverre Planke. I’ve edited their responses for brevity and clarity.
If you have any additional questions about LASI V, please feel free to leave your question in a comment below. I’ll forward your questions on to Henrik, Sverre, Christoph, and other LASI organizers. Hopefully, they will be able to provide you with an answer. You can also check out the official LASI website here.
LASI stands for Laccoliths and Sills. However, LASI workshops include study of all subvolcanic systems, which also includes dykes. I guess the acronym LASIDY just isn’t as catchy as LASI. The official title of LASI is “The physical geology of subvolcanic systems: laccoliths, sills and dykes.”
What are laccoliths, sills, and dykes?
Laccoliths, sills, and dykes are subvolcanic systems. That means that they represent the plumbing, so to speak, for volcanoes and other environments where volcanic rocks are extruded. They are often the link between magma chambers at depth and volcanic eruptions at the surface. They also represent what happens when magma doesn’t quite make it to the surface but rather is emplaced in the subsurface.
Some brief definitions:
Laccolith: A mass of igneous rock that did not make its way to the surface but rather spread out laterally, often in a lenticular or lens-like shape, and forced the overlying strata to deform upwards.
Sill: A tabular intrusion of igneous rock that is emplaced parallel to the pre-existing rock bedding. Most often, sills are originally horizontal or sub-horizontal.
Dyke: A tabular intrusion of igneous rock that is emplaced discordant to (i.e. cuts across) pre-existing rock bedding. Most often, dykes are originally vertical or subvertical.
I also asked the experts! Here’s what they had to say:
From Christoph:
Essentially, these are bodies of magmatic rock. A dyke is a conduit from a magma chamber in the lower crust or in the mantle towards the surface or near the surface. Dykes are vertical or almost vertical and generally tablet-shaped. In some situations, the magma doesn’t make it to the surface but will emplace in the upper crust— in the upper 500-1000 m, generally. However, the deepest known laccolith, which is in Utah, was emplaced at approximately 3 km depth. And these emplacements form horizontal or subhorizotal sheets of magmatic rock, such as dolerite, and these are known as sills. If there is enough magma volume and if the magma is viscous—that means a high silica content—then the emplacements tend to be laccoliths. A laccolith has a flat base and a lifted up, lentil-like shape. Sometimes, these laccoliths stay completely as a subvolcanic body, but if more magma is pumped in, they might pierce the surface, and there will be an eruption.
From Sverre:
I describe subvolcanic systems as rivers of magma that are running inside the rocks. A sill, for instance, is a horizontal river of magma. That’s an easy way to describe it.
A dolerite sill in the Karoo's Golden Valley.
Why is it important for geologists to understand subvolcanic systems?
From Christoph:
First of all, we have a scientific interest to understand how our “Spaceship Earth” that we are traveling on works. If we want to master the future, we need to know how the system has worked over the last 4.6 billion years. However, there are also a number of applied aspects to understanding subvolcanic systems. For example, we are on a field trip where we can see complex sill systems that have entered a sedimentary basin, and in other areas, such as in the North Sea, similar sill intrusion into a sedimentary basin influenced the formation of oil and gas. Also, emplacement of laccoliths can provoke landslides, so there is a hazard application. Another application is the research of Sverre Planke, Henrik Svensen, and others, who found that when huge subvolcanic systems intrude basins which are rich in organic carbon, they might provoke very fast degassing, which could lead to major climatic change that could trigger a mass extinction.
From Sverre:
There are three main applied areas for study of subvolcanic systems: the first is hydrocarbon exploration in volcanic basins, the second is ore deposits since many of the world’s large ore deposits were formed in or around subvolcanic systems, and the third is climate change since emplacement of subvolcanic systems is believed to have triggered global climate change numerous times in Earth’s history.
What is a LASI workshop?
LASI workshops are a regular (every 2-3 years) meeting of scientists who study subvolcanic systems. The workshop consists of 2 days of scientists presenting their research in talks and posters followed by a 1-3 day field trip to an area where subvolcanic systems can be observed in the field.
From Christoph:
LASI is multidisciplinary meeting of scientists who study subvolcanic systems. At LASI workshops we are looking at subvolcanic systems from many angles: petrology, geochemistry, physical geology, sedimentology, analog experiments, geophysics, numerical modeling, and so on. In a short time, within half a day of LASI, we see many connections across these disciplines, and it’s great fun.
LASI V participants checking out a dolerite sill which is undergoing spheroidal weathering.
How many people usually attend LASI workshops?
Between 40-50 people attend the LASI workshops. The workshops are mostly attended by researchers from Europe (Germany, Norway, Sweden, the UK, France, Germany, the Czech Republic, Poland, Russia, and other countries) and the United States. However, there have also been attendees from South Africa (especially at LASI V), Australia, and other countries. So far, there have not been many attendees from other places such as Asia. However, researchers from other parts of the world would be very welcome to attend future LASI workshops!
What is the history of the LASI workshops? How did the first LASI workshop come about?
From Christoph:
It’s a nice story. In the mid-90s I started to work in Central Europe in the Late Paleozoic systems, which are full of volcanic rocks and subvolcanic rocks. I worked in places such Germany, Poland, Czech Republic, Italy, and France. When I started to work around 1995 on these systems, I found out that there are many kinds of porphyritic rocks (in quarries and outcrops and drill cores), and I found that in many cases the formation of these rocks was not clear at all to the previous authors or the colleauges I talked to. I found out in particular that in the city of Helle in Eastern Germany there is an important complex of rhyolitic rocks (200 km3 of rocks), and I found out that researchers really had no idea how they were formed. So, I started to read literature on subvolcanic systems, such as laccoliths, and I started to contact researchers in that field.
I thought it would be a good idea to launch a symposium on subvolcanic systems at the European Geoscience Union conference around 2000 or 2001, but the organizers turned down the symposium. They said something like, “It doesn’t fit in our program.” But I went to EGU anyway for other purposes, and I met Nick Petford, who is a very good UK geologist, and I talked to him and I said, “Well, EGU turned down this symposium. Why don’t we organize something on our own on the topic of physical processes of subvolcanic systems?” And he said, “Well, that’s a great idea.” And so we spread the news that we would gather in Freiberg for three or four days. Astonishingly, more than 40 people showed up. We had a good meeting with a nice seminar and then a one day field trip that I would call rather modest compared to the other LASI field trips. After the first LASI, we thought that the next should be in the Isle of Skye in Scotland, but it took awhile to organize the next one, so the next one was four years later.
How are LASI workshops organized?
From Christoph:
As in many other scientific disciplines, in geology there are some forms of conferences that are very rigid in their procedures and requirements, and you feel as if you are in a big machine. In contrast, the LASI workshops are very low in terms of organization and are done in a very simple way. We just find some people who are willing to organize the workshop, and we spread the news on the internet. Then we see who wants to attend, and they just pay to cover the costs. The attendees usually submit abstracts although they even can attend without an abstract. There’s no committee, there’s no big reception ceremony, and there are no medals. It’s very laid-back. Every organizer has his own system of fundraising. For instance, when I organized the first LASI workshop I received funding from the German Research Foundation and from the state of Saxony where the workshop was held, and this worked quite well. Other groups are maybe more connected to companies—oil companies and mining companies—and receive funding from industry. But there are no rules, so the organizers just try to find funding for LASI wherever they can. When we’re planning the next LASI, we try to think of a good place for a field trip to subvolcanic systems, and we try to go different places—not always to Europe, for instance.Often, the next LASI comes around at dinner one night of the previous LASI. We’re sitting around the dinner table and someone says, “That’s a good idea for the next LASI. I can organize it.” There are no rules, no voting committees to decide where the next LASI will be. It’s very organic.
One of many beautiful sill-topped plateaus in the Karoo.
Have the LASI workshops led to some new directions for research on subvolcanic systems?
From Christoph:
I am all the time inspired. For example, at the first LASI workshop I was working on the Halle volcanic complex, and I was very inspired by some talks by German colleagues of mine. Their work inspired me and helped me get ideas for new research and publications on Halle. I guess this is the case for almost everyone, even the veterans of subvolcanic system research. So, there is cross-fertilizing all the time. And the other component of LASI is that we always combine it with field trips to very classic or important outcrops for subvolcanic systems, and so the dsicussions continue on the outcrops.
From Sverre:
Going to meetings is very important for research. The first time I was exposed to the Karoo was at the IAVCEI meeting in 1998 in Cape Town, South Africa. At the first LASI meeting we met various people working on sill emplacement in the UK, and some of them were offered postdoc positions at PGP in Norway and were part of the motivation for doing the Golden Valley studies that we’ve done here in the Karoo. Obviously, conferences are important for meeting people and getting ideas and presenting your own research.
LASI V participants taking a close look at a volcanic pipe.
Where have the previous LASI workshops been held?
They’ve been held all over the world! Here’s a webpage with information on them all, and here’s the list:
LASI I: Freiberg, Germany, 2002.
LASI II: Isle of Skye, Scotland, 2006.
LASI III: Elba Island, Italy, 2008.
LASI VI: Utah, USA, 2010.
LASI V: Port Elizabeth and the Karoo, South Africa, 2012.
Why did you decide to hold the LASI V conference in South Africa? Why are you having a field trip in South Africa’s Karoo region?
From Sverre:
I can say briefly why we [the Norwegian research group from PGP] are here. We are studying subvolcanic systems in seismic data in offshore of Norway, and we’ve been looking for good field analogues for what we see in the geophysical data. The Karoo is really the best place to see these type of complexes exposed. What you find in the Karoo is a very large sedimentary basin where you have numerous sills and dykes and other subvolcanic rocks exposed, and this is similar to what we see offshore of Norway. Here we can go out in the field and then we can compare the results from the Karoo with what we see in the seismic data offshore of Norway.
When and where will the next LASI workshop be held?
This is still to be determined. I overheard many tentative suggestions at the conference, but nothing has been confirmed. If you have a suggestion for a good location, please feel free to leave a comment below. Whenever and wherever, I hope that I have the opportunity to attend the next LASI workshop. I greatly enjoyed attending LASI V. Thanks so much to Henrik and Sverre for inviting me!
LASI V participant Sergio Rocchi takes a closer look at a dyke.
That’s all I have on LASI for now. In future posts you’ll learn much more about LASI V. Stay tuned!
Natrolite, a mineral belonging to the zeolite group. Mary's Peak, Oregon. Picture courtesy of Dana Hunter.
def. zeolite:
The name of a large group of porous, framework, aluminosilicate (their basic structure is interlocking tetrahedra of SiO4 and AlO4) minerals that contain significant water and also significant exchangeable cations, which makes them absorbent materials. The name zeolite originates from the Greek words “zeo”, which means “to boil”, and “lithos”, which means “stone”. Zeolites were given their name because when you heat them, they generally release water in the form of steam. There are dozens of minerals in the zeolite group. You can view a list of zeolite minerals here. Zeolites often form through the interaction of volcanic rocks and ash with alkaline groundwater. Thus, you can often find spectacular and very beautiful zeolite crystals inside vesicles and vugs (often creating amygdules or crystal-filled cavities) in volcanic rocks such as basalt. Zeolites also crystallize in shallow marine basins.
My good friend and fellow geoblogger Dana Hunter has provided me with zeolite pictures galore. She took these pictures during one of her geology trips with Lockwood DeWitt. Thanks for the pictures, Dana and Lockwood!
More Natrolite. Mary's Peak, Oregon. Picture courtesy of Dana Hunter.A zeolite amygdule (Lockwoods says consisting of mostly of the zeolite mineral stilbite) in a rock from Quartzville, Oregon. Picture courtesy of Dana Hunter.A closer view of the zeolite amygdule. Picture courtesy of Dana Hunter.More zeolite crystals from Quartzville, Oregon. Picture courtesy of Dana Hunter.More zeolite crystals from Quartzville, Oregon. Picture courtesy of Dana Hunter.
***Thanks to several of my twitter followers for suggesting this week’s word and to Dana and Lockwood for all the pictures!***
The LASI V field trip route in the Karoo Large Igneous Province. Image taken from the LASI V website: http://www.lasi5.com/
My husband and I just returned from Durban as well as South Africa’s “South Coast” and “Wild Coast”, where we enjoyed a lovely week of holiday to celebrate our 1-year wedding anniversary. We had a great time despite the rainy weather, and I took plenty of pictures which I’ll be sharing here on Georneys in due time.
We’re back home in Cape Town now, but tomorrow morning I fly out again. I’m headed to Port Elizabeth, South Africa to participate in something called LASI V, a workshop titled “The physical geology of subvolcanic systems: laccoliths, sills, and dykes.” LASI V consists of two days of talks and posters followed by a 4-day field trip to the Karoo Large Igneous Province. I’ve been invited to attend the conference by Dr. Henrik Svenson, a Senior Researcher at Physics of Geological Processes, a Norwegian Center of Excellence. Henrik has invited me to attend the workshop as a science writer… or, perhaps, as a science blogger. I’ll be taking notes (and pictures!) during the talks and field trip and writing up some blog posts which I’ll be sharing with you here on Georneys. If some of the LASI V participants are willing, I’m also hoping to do a few interviews (my voice recorder is packed!) and share edited transcripts of these interviews. I’m sure I’ll also have plenty of pictures to share from Port Elizabeth and the Karoo!
I’m excited and honored to be participating in the LASI V workshop. I’m so excited, in fact, that I’m even taking an extra week off from my day job to attend LASI V. The list of talks and posters looks great– you can download the Conference Program here. If there’s any talk or poster you particularly want me to blog about, please let me know in a comment below. I’m also looking forward to the field trip to the Karoo as I’ve been wanting to visit the Karoo for years. Certainly, the geology of the Karoo is currently a hot topic since several companies are interested in extracting shale gas from the Karoo, but there are concerns about the environmental impact of such gas extraction. As geologists working in South Africa, my husband and I (who work in gold exploration and know relatively little about shale gas) are often asked about what we think about “fracking and the Karoo” at dinner parties and such. We actually learned quite a bit about shale gas and the Karoo last week when we attended a talk by Dr. John Decker of PetroSA, who highlighted how much more research needs to be done just to properly estimate the amount of shale gas in the Karoo, let alone to assess any potential environmental impacts of gas extraction. Perhaps after attending LASI V next week I’ll at least be able to talk more about the geology of the Karoo– if not shale gas and fracking– at dinner parties.
Anyway, I need to finish (re-)packing now, but stay tuned for more about LASI V and the Karoo!
Bourke's Luck Potholes #1. Photo courtesy of Bonita and Jonathan Hall.
My sister-in-law Bonita was married last month. For her honeymoon she and her new husband Jonathan went to the Mpumalanga region of South Africa. Bonita and Jonathan saw some incredible geology on their honeymoon, and they’ve kindly given me permission to share some of their pictures here on Georneys. Today I am sharing some pictures of their visit to Bourke’s Luck Potholes. Impressive potholes, aren’t they?
Bourke's Luck Potholes #2. Photo courtesy of Bonita and Jonathan Hall.Bourke's Luck Potholes #3. Photo courtesy of Bonita and Jonathan Hall.Bourke's Luck Potholes #4. Photo courtesy of Bonita and Jonathan Hall.
def. Yellowstone National Park:
A United States national park that is located in the states of Wyoming, Montana, and Idaho. Established in 1872, Yellowstone was the first national park to be founded and set an example for other national parks which were subsequently established all over the world. The park is the current location of the Yellowstone hotspot, which is responsible for large-scale volcanism in Oregon, Nevada, Idaho, and Wyoming. As a result of the hotspot, the park is full of geothermal features such as hotsprings and geysers… and thus is a treasured location for geologists to visit!
For this week’s geology word, I thought I would share some pictures from when I visited Yellowstone National Park as part of my undergraduate geology field camp back in 2005. I haven’t been back to Yellowstone since then, but my husband and I are hoping to visit sometime in 2013 as part of a Western USA roadtrip that we’re plotting.
Does anyone else have some Yellowstone pictures to share? Perhaps we can start a geomeme!
Yellowstone #2. Fall 2005.Yellowstone #3. Fall 2005.Yellowstone #4. Fall 2005.Yellowstone #5. Fall 2005.Yellowstone #6. Fall 2005.Yellowstone #7. Fall 2005.
A view from near the top of Judas Peak, October 2012.
Yesterday (Sunday) I went on a hike up Judas Peak, one peaks in the Twelve Apostles range, which flanks Table Mountain and overlooks beautiful Hout Bay. On clear days, there is a gorgeous 360 degree view from the top of Judas Peak. The picture above shows the inselberg of Lion’s Head,which is another great peak to hike. I feel very fortunate to live in such a beautiful part of the world and to have a group of friends who enjoy hiking and other outdoor activities. Now that I’m in South Africa more-or-less full time, my husband and I are going to try to hike with friends at least one weekend a month. So, I’ll probably share more pictures from our hikes in the future.
A model of a live Xiphactinus. Photo courtesy of Ron Schott.
def. Xiphactinus:
1. A large (15-20 ft long), predatory fish that lived during the Late Cretaceous.
2. A prehistoric sea monster. Seriously. What an enormous and scary looking fish.
3. A really, really cool fossil. Maybe one day I can display one in the library of my evil geologist lair.
One of the most famous fossils of Xiphactinus is the “fish within a fish” fossil located at the Sternberg Museum of Natural History in Hays, Kansas. Ron Schott visited the museum several months ago and took many pictures as well as an incredible Gigapan of the “fish within a fish” fossil and some of the associated displays. Ron describes:
The centerpiece of the Sternberg Museum of Natural History in Hays, Kansas is the world renowned “Fish Within a Fish”. This remarkably complete sample from Gove County, Kansas is of a fourteen foot long Xiphactinus that had ingested an eight foot long Gillicus shortly before its demise in the Western Interior Seaway some 80 million years ago.
Here are some pictures that Ron took of Xiphactinus:
A fossil fish within a fossil fish. Very cool! Photo courtesy of Ron Schott.Another view of the "fish within a fish" fossil. Photo courtesy of Ron Schott.A closer view of the big fish's head. Look at those teeth! Photo courtesy of Ron Schott.Scary fish teeth! Photo courtesy of Ron Schott.A Xiphactinus skull. Photo courtesy of Ron Schott.A reconstruction of the excavation of a Xiphactinus fossil. The model person gives a good sense of scale-- this is an enormous fish! Photo courtesy of Ron Schott.Another view of the model excavation. Photo courtesy of Ron Schott.Scary Xiphactinus mouth. Photo courtesy of Ron Schott.Boo! Photo courtesy of Ron Schott.
***Thanks to Ron Schott for suggesting this week’s word and providing all the wonderful scary pictures.***
Georneys 