What do volcanic bombs, xenoliths, and giant gypsum crystals have in common?

June 7th, 2012

FILLMORE, UTAH – What do volcanic bombs, xenoliths, and giant gypsum crystals have in common? Not much, except that we saw them all during our long and productive day. We met to pack lunches at 7:30 am and finished with student-faculty meetings at 10 pm, so we’re all ready for a good night’s rest, but we thought we’d give you a quick update on our progress.

We spent the morning as a mob on the rim of the cinder cone, searching for volcanic bombs for Will's ballistics study.

Will found a wide variety of bombs, or material that was explosively ejected from the volcano when it was molten. He made a number of measurements that he'll use in his mathematical models when he returns to Wooster.

In the afternoon, Kevin led a group to look for xenoliths, or foreign rock fragments, in a lava flow. This sedimentary xenolith is affectionately named Neopolitan.

At the end of the day, we visited with Larry Gehre, who so graciously showed us his amazing personal collection of rocks. If you have a sandstone feature in your aquarium, it probably came from Larry.

We were all impressed the size of the gypsum crystals in his scrap pile. Note Will's hat for scale.

Although it was long and challenging, the cool temperatures and partly cloudy skies made for a pleasant day in the field. Back to the lava fields tomorrow to check out some scarps and map flow boundaries. Wish us luck!

As We Walk Through Fields of Lava

June 6th, 2012

FILLMORE, UTAH – Whitney and Matt took charge today, leading us on an investigation of the lava flows that extend westward from the Miter cinder cone.

The view of Miter from its lava fields. A tiny reflective spec at its base on the right side of the photo is our van, for scale.

We picked our way across the sharp, rubbly flow surface and learned the importance of careful observation. Although we weren’t looking for bombs and xenoliths, we found both along our path.

A volcanic bomb that has been rafted or carried away from the cone by the lava flow.

Whitney had a successful day of mapping the margins and morphology of a couple of complicated lava flows.

Whitney stands on the boundary between an older, vegetated lava flow on the right and a younger, black lava flow on the left.

Matt’s productive day included finding a spectacular fault exposure, where he made lots of measurements on the fault and associated joints.

Kevin poses at the most significant fault locality, where some of the surfaces display plumose structures for joints and striae for fault motion.

Overall, it was a strong start to the field project, despite the searing sun and blinding wind storm.

A perfectly nice day in the field (if you don't mind winds that will make your hair stand straight out).

We were rewarded for all of our hard work.

For one, we made a new friend.

We also found petroglyphs that showed these radiating straight lines.

The petroglyphs also showed a hand print.

The best reward was the home-cooked meal that we were treated to by Ms. Huntsman, complete with pie.

We hope every day of our field season is just like this one (minus the wind).

 

Orientation in Ice Springs Volcanic Field

June 4th, 2012

FILLMORE, UTAH – [Guest bloggers Kevin Silver and Tricia Hall]

The alarms sounded in the early morning sun, early enough for the outside air to chill the bones. After our standard yogurt and cereal breakfast, we piled into the van and made our way to the Ice Springs volcanic field, the site of our field work for Independent Study. By chance, we met the manager of the quarry along the narrow road in a near head on collision before making our way up the winding road of the cinder cone with the manager’s warnings of careless truck drivers at the forefront of our minds. Once we arrived at the top of the cinder cone, we were able to enjoy the incredible views of the surrounding valley. The first feature we came to was the Crescent crater. As we viewed the expanse of the lava flow below us, it became quite clear at this point that trying to map the entire field would take much longer than the two short weeks that we have to work in Ice Springs.

Looking northeast from the summit of Crescent Crater.

 

After becoming oriented with the area, we made our way to Miter crater and came across extensive exposures of xenoliths. We paused for a snack and to reapply sunscreen before heading out onto the lava flows, and it was here we realized a harsh reality. The lava flows are very complex, but luckily provided better footing than the cinder of the crater slopes. Assessing the lava flows led us to the flows breaching Miter crater. The ascent back up Miter crater proved to be more challenging than expected, but we were truly independent minds working together to find flat ground. Once everybody caught their breath, we wandered back toward the van to make our way back down the cinder cone. We then made an attempt at circumnavigating the volcanic field using the rather primitive roads that were more attuned to cattle herds than cars. This feat proved to be futile as nothing less than an ATV could navigate the rough terrain we encountered. Upon our misfortune, and the near loss of our bumper, we decided to head back to camp. Along the way, we all took a nap, leaving poor Dr. Judge and Dr. Pollock to navigate our group safely back to the camp site in silence.

Tricia Hall standing in front of Miter Crater.

Once back in our accommodations, the kozy kabins, we all went our separate ways for some R&R. We each met individually with the professors to discuss our project ideas once again following our initial introduction to our field site.

Around 5:30 pm, we all piled into the van once more to scavenge for nutrients at the quality establishment known as 5 Buck Pizza. We had 4 of them. They were good. Will and Matt guzzled 8 pieces of pizza each, leaving the rest of us starving.

 

Wooster Geologist on the Blue Ridge of Virginia

June 3rd, 2012

The summer field season has started for Wooster geologists. Greg Wiles is now in southern Alaska with his students doing dendrochronology and geomorphology. Meagen Pollock and Shelley Judge are running an integrated project in west-central Utah with their students doing structural geology, geochemistry, vulcanism and petrology. Watch these pages for their reports!

As for me, I’m on a short vacation. A geologically-rich vacation, of course! My wife Gloria and I are visiting the Shenandoah region of Virginia. We started today in Shenandoah National Park, driving south down Skyline Drive along the Blue Ridge. The weather is spectacular as you can tell from the above image. This is a view near Mile 61 looking west across the Valley and Ridge Province.
The Blue Ridge Province has a bedrock made of igneous and metamorphic Grenville basement rocks up to a billion years old. The Blue Ridge itself, which runs north-south from Pennsylvania to Georgia, is mostly an eroded anticline overturned westward. Directly west is the Valley and Ridge Province. In the image above, the “A” is at the spot where the top photograph was taken. You can easily pick out the physiographic and geological provinces.

Most of the rocks exposed along Skyline Drive in Shenandoah National Park are metabasalts of the Catoctin Formation (Ediacaran, about 570 million years old). A metabasalt is a basalt that has been metamorphosed (unsurprisingly). The original basalts of the Catoctin were erupted during the rifting open of the Iapetus Ocean, a precursor of the Atlantic. Many of these eruptions were on this early seafloor, forming pillows and thick flows. The total basalts in this formation piled up in layers to almost 800 meters thick.
The metabasalt of the Catoctin has a greenish color in many places, giving it the common name “greenstone”. Veins of green minerals, primarily epidote and chlorite, run through the rock, especially in the northern part of the Blue Ridge. This greenstone is occasionally mined to produced chemical-resistant lab surfaces and facing stones.

The dramatic geology was accompanied by beautiful wildflowers. The rocks, flowers, views and weather combined to make an extraordinary day of natural history. Tomorrow we’ll explore how this geology affected human history in very direct ways.

Aquilegia canadensis (Red Columbine).

Penstemon canescens (Hairy Beardtongue).

Theory to Practice: An Early GSA Abstract

May 11th, 2012

This semester, I’ve had the pleasure of teaching a special topics lab course in geochemistry. Given our new lab facilities, I decided to approach the class as an analytical geochemistry course. We explored sampling strategies, data quality, and the theory and techniques behind X-ray methods (XRF), electron-beam methods (SEM-EDS), and mass spectroscopy methods (ICP-MS).  Unlike a typical survey course, our course was entirely research-based. We actually became analytical geochemists by conducting an authentic research project on a suite of Icelandic basalts. Our goal was to investigate the development of a structural basin in northern Iceland by interpreting the petrogenesis of lavas that were erupted during different phases of basin construction. This week, we’ve accomplished our goal and have written an abstract to submit to the Fall 2012 meeting of GSA.

Here is the text of the abstract:

A GEOCHEMICAL ANALYSIS OF THE VATNSDALFJALL STRUCTURAL BASIN, SKAGI PENINSULA, NORTHWEST ICELAND

Matthew Peppers, Sarah Appleton, Lindsey Bowman, Andrew Collins, Whitney Sims, Melissa Torma, Meagen Pollock

Vatnsdalfjall, in northwest Iceland, exposes the upper ~700 m of crust formed ~7 Ma ago at the extinct Hunafloi-Skagi rift zone. In general, the lava flows dip gently westward toward the abandoned rift axis, but are interrupted by a local area of steeply dipping lava flows known as the Vatnsdalur Structural Basin (VSB). The VSB is composed of three sequences of lava flows emplaced before, during, and after subsidence. Using the geochemistry (XRF, ICP-MS) of samples gathered in the field in 2006 and 2007 and previous data from Ackerly (2004) and McClanahan (2004), we were able to establish a basic eruptive history for the sequences. Major element analysis shows diverse rock types, including basalt, basaltic andesite, dacite, and rhyolite. Sequence 1 shows the greatest diversity and was primarily affected by mineral accumulation, while Sequences 2, 3, and the dikes follow the trend of a shallow level fractional crystallization model based on a modified parent magma from Sequence 1. Trace element ratios suggest the presence of 1 (or 2) parent magmas, although the intermediate to silicic lavas appear to be generated by a separate process. Sequence 1 contains various lava flows, each with a uniform thickness, emplaced on relatively flat terrain. Sequence 2 was emplaced on top of Sequence 1 as subsidence of the basin was occurring, creating lava flows that thicken toward the basin interior. Intermediate to silicic rocks are absent during this interval and dikes cut Sequence 1 to feed lavas in Sequence 2. After a period of erosion, Sequence 3 was erupted above Sequence 2. Dikes that feed Sequence 3 cut through Sequence 2. The development of the VSB may have been associated with a waning period in the magmatic system, where magmas cooled and evolved (following an evolutionary trend controlled by fractional crystallization) and there was little partial melting of the crust (given the lack of intermediate to silicic lavas).

And some key figures:

Geologic map that shows the location of our samples on Sequence 1 (green), Sequence 2 (pink), and Sequence 3 (blue).

CaO vs. MgO (wt%). Symbols for dikes and Sequences 1, 2, and 3 are as shown on the geologic map. Previous data outlined by the dashed line. Fractional crystallization model shown by the black like. Arrows indicate effects of mineral accumulation. Plagioclase (pentagons) and clinopyroxene (stars) are also shown.

Schematic model (not to scale) for the development of the basin.

I applaud all of the students for their excellent work. They really took ownership of this project and deserve all of the credit. Look for us at GSA in the fall!

Keck Mission Accomplished

August 7th, 2011

WOOSTER, OH – After a month of hard work, the Iceland Keck group parted ways on Saturday. We arrived in Wooster immediately after returning from Iceland and put in a solid week of work in the lab, preparing our samples for thin sections and XRF analyses. In one week, the students produced over 120 thin section billets, powders, and pressed pellets, and almost as many glass beads. Even though the work was tedious and the hours were long, I think we’re all glad that we’ll have data at the start of the school year. Well done, team!

A dessicator full of pressed pellets ready to analyze on the XRF.

 

Challenges of lab work. We tracked the number of samples that were prepared. This student prepped 20 pressed pellets "of varying degrees of brilliance + some epic failures."

Katharine works her magic on the scale.

Erica grinds the saw marks off of her sample.

Nina presses a brilliant pellet.

Thad oxidizes his samples in the muffle furnace.

Emily celebrates a glass bead that hasn't cracked.

Brennan and Katie troubleshoot the GIS file.

Of course, our work isn’t complete. Once we have the chemistry and thin section observations, we can put the data into the context of the mapped field relationships to understand the volcanic history of one of the oldest central volcanoes in Iceland. We’ll have much to present at the Keck Symposium in the spring and are already looking forward to our reunion.

A Keck Adventure at 66 North

July 28th, 2011

West Fjords, Iceland – We’re happy to report that the 2011 Iceland Keck crew has safely completed a productive field season. Nearly two weeks ago, a boat dropped us off in Hornstrandir, a nature preserve that encompasses most of the northern portion of the West Fjords. Our field area centered around Hrafnsfjordur, or Raven Fjord, in the southern extent of Hornstrandir. We had no idea that Hrafnsfjordur was a popular destination; it’s one of the primary drop-off and pick-up points for backpackers in the region. We must have seen at least half a dozen hikers during our stay. Hiking trails snake their way around the fjord and over the passes, which was fortunate for us since we had to access all of our field areas on foot.

A very still day in Hrafnsfjordur.

After a couple of days of recon hiking as a group, the students selected their projects and went to work. Most students chose to map a portion of the fjord, although one student focused on mapping and sampling dikes. Students worked in teams of two, each team being assisted by a faculty member.

A very sunny day in Hornstrandir.

Field work was challenging. Like our Alaskan colleagues, we had dramatic stream crossings, treks across snow, and hikes up steep terrain. Although we never saw a bear, we spotted an arctic fox in the distance. Thankfully, the fox wasn’t interested in our food. Dehydrated meals at the end of a long field day never tasted so good!

Coast guard performing drills outside our hostel in Isafjordur.

The weather was mostly good, by Iceland standards. It seems as if we were constantly confronted with either bugs, wind, or rain, but always just one at a time. Whenever Emily worked in her area, though, the sun would shine!

Hiking up snow to reach the peak.

We took a chartered boat back to Isafjordur on Wednesday and spent one last day in the field mapping a local mountain called Sauratindur. Now that we’re finished with field work and have returned to civilization, we realize how thankful we are for hot showers and soft mattresses. Still, there are some things that we’re already missing: the view from our tents, the sound of the waterfall (especially at night), the soft moss, our own private fjord, the hot cocoa, our special treat at the end of each day, and the freshness of the air.

Our Keck adventure in Hrafnsfjordur, in Hornstrandir.

Tomorrow, we start our long journey back to the states (via Reykjavik). We’re eager to get back to Wooster to start processing our samples. Hrafnsfjordur offered us an amazing amount of what we think are intermediate lava flows, which would be unique for Iceland. Dominated by basalt with local regions of rhyolite around central volcanoes, intermediate lavas are relatively sparse. Our field mapping, thin section observations, and geochemical analyses should yield some insights into the formation of Hrafnsfjordur’s central volcano. Stay tuned!

Panorama from the top of Manafell in Hrafnsfjordur.

Students playing a game of rock while waiting on the boat.

Textbook hanging valley in Isafjordur.

The boat that came to pick us up- one trip for gear and rocks!

The view from my tent in Hranfsfjordur, Keck.

Familiar scene for geo types- hiking up waterfall cuts for good exposure.

2011 Keck Iceland is Official

July 15th, 2011

2011 Keck Iceland Group on columns.

ICELAND – As Lindsey and Travis were leaving Iceland, the Keck students were arriving. The Keck Geology Consortium consists of 18 schools whose geology departments are dedicated to providing undergraduates with high-quality research experiences. Funded through NSF and contributions from its members, the Keck Consortium supports several research projects each year. This year, I’m working with Dr. Brennan Jordan (University of South Dakota) on a 6-student Keck project in the West Fjords of Iceland. We’ll spend three weeks working in the field, then return to Wooster for another week in the lab.

After spending a day in Reykjavik recovering from jet lag and getting to know each other, we left for a four-day field trip to south central Iceland. The field trip serves several purposes: (1) build a sense of community, (2) get a sense for the provisions we’ll need in the field, and (3) observe geologic features that might be exposed in our study site.

We started by touring the Reykjanes Peninsula, visiting some sites that Travis and Lindsey had just seen. We observed marine pillow basalts, tuffs with embedded blocks, a dike feeding a lava flow, and lots of fissures. We ended the first day at Thingvellir and had our first taste of the dehydrated meals that will be our dinners for the time we’re in our field area. We all agreed that they tasted better and were more filling than we expected!

The second day began at an amazing exposure of subglacial pillow basalts. We almost didn’t get to visit this site because a film crew was shooting a car commercial at the exposure (complete with a thundering herd of Icelandic horses). Fortunately, they were kind enough to let us in for a short time, and it was worth it! Afterward, we visited Geysir (the original) and Gullfoss, where we saw glacial striations and a stunning waterfall.

Amazing pillow basalts near Thingvellir.

The second day ended (and the third day began) at Landmannalauger, a popular hot spring destination (I’ll let the Keck students tell you about their hot spring experience). Landmannalauger is surrounded by rhyolite slopes that form the walls of a giant caldera. Just behind the campground, a hiking trail winds its way over a blocky rhyolite flow, where we observed lots of flow banding, obsidian, and pumice altered to a beautiful green color. On the way out of Landmannalauger, we saw a few more rhyolite flows, a gorgeous cinder cone, and some Hekla tephra. You may recall that Hekla was recently reported in the news as “ready to erupt.” Rest assured that all was peaceful when we were there.

Before we returned to Reykjavik on the last day, we made a couple of quick stops in south-central Iceland near Dyrholaey to see spectacular columnar joints.

Dike intruding through tuff on the southern Reykjanes peninsula.

Back in Reykjavik, we caught our flight to Isafjordur in the West Fjords. We’re all eager and ready to go to our field site. Having seen a wide range of geologic features, we feel prepared for whatever our field site offers. Tomorrow, we’ll take a boat to the site, one of the most remote places in Iceland. Look for another post when we return from the field. Wish us luck!

*Sorry about the lack of pictures! If you know a way to post pictures to a blog from the iPad, please let me know! As an alternative, feel free to check out the pictures that I’ve posted on my twitter feed: twitter.com/meagenpollock

[Images added on July 18, 2011, from Meagen Pollock's Twitter feed.]

A Day in Akureyri

July 9th, 2011

AKUREYRI, ICELAND – Since we finished Travis’ field work a day early, we were able to spend Friday in Akureyri, Iceland’s second-largest city. Akureyri has an idyllic location, nestled between a fjord and snow-capped mountains in north-central Iceland.

 

Snow-capped peaks make a scenic background for Akureyri.

Our first stop was at the Botanical Gardens, which hosted a surprising variety of plants, given Akureyri’s rugged climate. We saw some familiar flowers that reminded us of the field:

 

This yellow flower was common in our field areas (it's Icelandic name is Argentina egedii Skeljamura).

We saw this delicate purple flower often, too (Viola canina Tysfjola).

This sweet flower grew in the jagged spaces between rock piles (Silene uniflora Holurt).

There were other flowers that were more exotic:

 

The vivid blue petals of this Meconopsis grandis Fagurblasol were stunning.

And then there were flowers that were much too familiar:

 

A well-established specimen of our friend, the dandelion.

Next to the Botanical Gardens, we contemplated statues on the campus of Akureyri’s University.

 

Dr. Pollock interpreted this sculpture to mean that basalt is the foundation of the world.

Next, we admired the Akureyrarkirkja, a columnar basalt-themed church that was designed by the same architect who built Reykjavik’s famous Hallgrimskirkja.

 

The Akureyrarkirkja.

Finally, we visited the historic district for some food and shopping.

 

View of historic Akureyri. We highly recommend Cafe Paris, in the blue building on the right. The soup and bread is delicious!

 

 

 

Perhaps a little light reading for the trip home?

 

Lindsey and Dr. Pollock find hats for their next field experience.

A day in Akureyri was the perfect way to celebrate the successful end of two I.S. field projects. We happily headed back to our cabin in Blonduos, where we packed up for our journey back to Hafnarfjordur and started working on our GSA abstracts, which our Estonian colleagues have inspired.

Return to Vatnsdalfjall

July 9th, 2011

BLONDUOS, ICELAND – Meagen and guest blogger, Travis

We returned to Vatnsdalfjall for the second day of field work on the Monocline. The weather was the best we’ve experienced in Iceland yet.

View of the steeply dipping Monocline as it dives under the Hjallin Lens.

After a long hike through fields of sadness (so named by a previous IS student), we finally made it to our first exposure. We found lots of interesting amygdules (filled vesicles):

Vesicles half-filled with chalcedony in horizontal layers suggests that the lavas were tilted before the chalcedony precipitated.

Zeolites come in a variety of habits, including these hair-like fibers that are about 1 cm long.

We sampled and made observations all of the way to the top of the Monocline. We were quite pleased with ourselves when we made it to the top, and slightly surprised to see that it was already 8 pm! In the land of the midnight sun, field work could last for 24 hours a day.

Lindsey and Travis getting ready to head down the mountain at 8 pm at night.

After such a hard day of work, we relaxed in the evening and made plans to visit Akureyri the next day.

Travis relaxes in the hot tub.

 

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