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GeoTalk: Stacia Gordon

Geotalk is a regular feature highlighting early career researchers and their work. Following the EGU General Assembly, we spoke to Stacia Gordon, the winner of the Tectonics and Structural Geology Division Outstanding Young Scientist Award, 2014.

Meet Stacia! (Credit: Stacia M. Gordon)

Meet Stacia! (Credit: Stacia M. Gordon)

First, could you introduce yourself and tell us a little more about your career path so far?

My name is Stacia Gordon. I am an Assistant Professor at the University of Nevada, Reno (UNR). This fall marks the start of my fifth year at UNR. It is amazing how fast the time has gone by! As an assistant professor, I quickly learned that being successful means being a good juggler and having good time management, as there are so many things that require attendance on a day to day basis…..graduate students, undergraduate students, manuscripts, data reduction, teaching, proposals, service work, etc. Prior to UNR, I had many amazing mentors that helped teach me how to manage all of these tasks that are required of you as a professor. Before I moved to UNR, I spent a semester at the Lamont-Doherty Earth Observatory (LDEO) under the Marie Tharp Fellowship, working with Dr. Peter Kelemen. This was an excellent opportunity to collaborate with a great scientist and meet and interact with many other scientists through the numerous seminars that occur every week at LDEO. LDEO also has the most well-organized intramural sports activities of any Earth Science department. Thus, I thoroughly enjoyed taking a break from science to go play soccer during the week.

I also had an excellent mentor during my postdoctoral research at the University of California-Santa Barbara, working with Dr. Brad Hacker. I think I spent nearly half of the postdoc away from UCSB, traveling for meetings, fieldwork, and lab work, but I learned a large amount of science and various writing tips for submitting a successful proposal from Brad. Brad also introduced me to many new collaborators (most notably Tim Little, Laura Wallace, and Susan Ellis). In addition, spending free time in Santa Barbara is not too shabby, with its lovely combination of ocean and mountains.

My real passion for understanding the mid- to lower-crust began during my dissertation work, while studying under Drs. Donna Whitney and Christian Teyssier at the University of Minnesota. I owe a tremendous amount of gratitude to Donna and Christian and am very happy that I continue to collaborate with them today. In addition, the STAMP (structure, tectonics and metamorphic petrology) group at the U always provided a support network of individuals in which to bounce ideas off of, ask questions, have a beer with, etc. Finally, my dissertation project also introduced me to Bob Miller and Sam Bowring. Both of whom I continue to collaborate with today, and they both had a great influence on my upbringing as a geoscientist. While it was extremely cold living during the winters in Minnesota, the Twin Cities and Pillsbury Hall (where the geology department is housed) were always warm, welcoming places.

 

During EGU 2014, you received a Division Outstanding Young Scientists Award for your work on integration of microstructural data with geochronology, metamorphic petrology, and geochemistry. Could you tell us a bit more about your research in this area?

I am very interested in understanding the thermal, chemical and rheologic changes that occur during orogenesis, and specifically understanding the interaction and timing among processes, such as metamorphism, deformation, and partial melting. I have been working on these processes in a variety of tectonic environments, from ultrahigh-pressure terranes (Papua New Guinea, the Western Gneiss Region of Norway) to regions where mid- to lower-crustal rocks are exhumed (North Cascades of Washington, eastern Bhutan in Bhutan). I use a combination of field and laboratory work, including various types of geochronology (high-spatial resolution techniques: ion microprobe and laser-ablation inductively coupled plasma mass spectrometry (ICPMS); and high-precision technique: thermal ionization mass spectrometry), ICPMS trace-element analyses, ion microprobe oxygen-isotope analyses, EMPA chemical analyses. These tools allow me to decipher the pressure-temperature-deformation-time path that the rocks underwent within these terranes. Knowing how and when the rocks were deforming and the maximum depths that the rocks reached allows geoscientists to better understand the processes that led to the burial and the exhumation of mid- to lower-crustal rocks. This also contributes to understanding how mountain belts grow and evolve through time, from when the crustal is thickening to when the mountain belt undergoes collapse and extends, falling apart.

 

What sparked your interest in tectonic processes and what inspired you to use the innovative approach, for which you’ve been recognised, to better understand mountain building and subduction?

This may sound a bit cliché but my interest in tectonic processes began as a child. I was raised in the mid-west of the United States, which has been heavily glaciated and is thus the topography is flat. My family would take vacations to the Western United States where I would see the Rocky Mountains and the Cordillera, both significant orogenic belts. As I child, I wondered why some areas were flat and others mountainous. I decided when I reached the University to take a geology class. After taking Geology 101, an introduction geology class, I specifically became interested in hard-rock geology. I found it fascinating that rocks of the mid- to lower-crust have reached high-enough temperatures to ductilely flow, and I was very interested in understanding how orogenic belts rest upon this very weak, ductilely flowing base. In addition, I was (and still am) fascinated that parts of the crust are taken, via subduction, to mantle depths and are brought back to the surface. My undergraduate research advisor was working on some of these high-pressure rocks exposed in Poland, and I was able to do a small project with him on these rocks. Thus, by the end of my undergraduate education, my interest in hard-rock geology was well developed.

Stacia in  Bhutan. (Credit: Stacia M. Gordon)

Stacia in Bhutan. (Credit: Stacia M. Gordon)

At the General Assembly in 2014 you gave an oral presentation about the findings of your research on the Western Gneiss Region, Norway. Could you tells more about the key findings you presented there?

I have been working in the Western Gneiss Region (WGR) since my postdoc. Brad Hacker introduced me to these incredible rocks, and since this time, Donna Whitney, Christian Teyssier, Haakon Fossen and I have been collaborating, with students, on various parts of the WGR. Within this terrane, it is divided into an ultrahigh-pressure portion (i.e., rocks that were exhumed from mantle depths) and a portion that appears to have also undergone high pressures but that also achieved high-temperature conditions. Within both of these portions of the WGR, there are mafic rocks that are hosted by migmatitic gneisses that underwent partial melting. We have been studying the partial melting history for the WGR because when melt is present, it will be very buoyant. This buoyancy may help exhume rocks from mantle depths. In addition, a small percentage of melt (~7%) will drastically decrease the strength of the rocks; therefore, the melt will play a significant role in how the mountain belt is deforming through time. I have dated numerous of the now crystallized melt bodies and have found that many of the dates that record the timing of melting overlap in time with when the mafic rocks were undergoing metamorphism in the mantle. Thus, this suggests and supports field and experimental evidence from other studies/investigators that partial melting began at mantle depths and may have triggered the switch from the mafic rocks residing in the mantle to being exhumed toward Earth’s surface.

In addition, as mentioned above, we have analysed samples from both portions of the WGR, and we find that the timing of the partial melting is consistent across the entire WGR. This represents a significant portion of the central-western coast of Norway shared the same melting history and thus implies that melting was ubiquitous at the end stages of this mountain building event and likely helped to drive the exhumation of these high-grade rocks back to the surface.

 

Generally speaking, what are the main challenges when trying to understand the processes that govern burial and exhumation of rocks?

Probably the hardest part about trying to understand these processes is being able to decipher the different parts of the burial and exhumation history. The laboratory tools that I use to understand the pressure-temperature-deformation-time path uses the chemistry of the minerals found in metamorphic rocks. The chemistry of these minerals can preserve a record of multiple thermal events that have occurred over time, and this allows geoscientists to understand both the burial and exhumation history. However, in some cases, the earlier history can become overprinted or erased so that it is difficult to know what happened prior to the exhumation history of the rocks. I would say this is one of the biggest challenges in understanding these challenging rocks.

Field work in Bhutan. (Credit: Stacia M. Gordon)

Field work in Bhutan. (Credit: Stacia M. Gordon)

 

During field work there are highs and lows, and as your research has taken you to some pretty interesting localities, (Bhutan, Norway, Papua New Guinea) no doubt you’ve had some memorable field work moments whilst at the same time overcoming some tough challenges. Can you tell us more about your field work highs and lows?

The overall high for pretty much all of the places I have worked (besides the rocks) is the scenery: all of these countries are beautiful places. Also, high in the list is the opportunity to meet with local people and see lots of different cultures. Many of these places (e.g., Papua New Guinea and Tajikistan) I would likely have not travelled to as a tourist so I have really enjoyed being able to go there for the geology. In particular, when traveling to countries as a geologist, you likely get off the beaten path very quickly and so I think it is a view of many places that a typical tourist does not see.

There are definitely challenges to working in a variety of these places. In many of the foreign localities, there is a significant communication barrier, where I don’t speak the local language, but we have found some locals who speak English to help with the field work. However, commonly, their English is weak so there is constantly miscommunication about what we want to do, which means that there are constantly evolving plans. This can be very frustrating as typically we want to target very specific rocks that are exposed in very specific geographic locations. It is not until we are in the country that we find out that it is not possible to get to a particular location, which after planning for a trip for multiple months before the field work, can be maddening.

Papua New Guinea (PNG) has definitely been one of the most amazing places to work but also the most frustrating. Most of the people are very kind, but there are also many that assume that as a foreigner from the United States that you have lots of money and are trying to exploit the locals in some way. Thus, we spent many a hours talking to people, explaining what we were doing and trying to get permission to work our way up rivers (where the rocks are exposed). In some cases, the locals would either flat out refuse our request to go up the river or would want a significant amount of money meaning that we would have to turn around and give up on a certain trek. On my two trips to PNG, however, we worked with some fantastic local guides that led us up the rivers. The rocks in the rivers were very slippery, and we would easily fall multiple times throughout the day. The local guides, however, would never slip, carried our heavy back packs, and did it all barefoot! They had the most incredible balance and were extremely savvy with using the local jungle to produce whatever they would need in that moment. For example, at one point, we came to a waterfall that we could not scale. Within 15 minutes, our guides had cut down trees, found vines to use as rope, and built us a ladder to go up and over the waterfall! There were multiple incidents like this that we foreigners would watch in awe!

Field work is definitely one of my favourite parts of the job. I don’t have to sit at a desk all day but instead, get to hike around beautiful mountains. Thus, there definitely many more highs than lows that I have found in all of the places I have worked.

Finally, what does the future hold for you in terms of your research and career plans?

I would like to continue working on some of my current research interests but look forward to developing new skills, investigating new research avenues, mentoring many new graduate students, and collaborating with many new individuals! What I have learned from being a Geoscientist thus far is that there are many questions still to be answered about Earth and that as one researches a topic or chats with a colleague, that new research ideas quickly form.

Imaggeo on Mondays: Gothic Snow Architecture.

Whilst on a family holiday in Norway, Gerrit de Rooij took this incredible photograph of an ice arch. Understandably geoscience is not his top priority whilst taking photographs on holiday, however Gerrit points out that pretty much every picture of a landscape has hydrology in there somewhere”, as he goes on to describe below.

This picture was taken near Balestrand, a village along the Sognefjord in Norway (Norway’s largest fjord and the second largest in the world!). The altitude was approximately 900 m above sea level (asl), and not always does all snow vanish during summer over there (we were there in August 2013). What you can see in the picture are the remnants of a much thicker snow pack that covered the stream that trickles down. On the right hand side you can see a glimpse of the other side of the arch that  must have gradually been carved out by the stream during the snow melt season (as they call spring over there). Once a tunnel was carved out, thaw took over. The black lines of rock dust on the ridges of the snow arch presumably were left behind by water streaming down along them from the top of the melting snow cover. In the top rim the source of this material is still visible.

Gothic Snow Architecture. (Credit: Gerrit de Rooij via imaggeo.egu.eu)

Gothic Snow Architecture. (Credit: Gerrit de Rooij via imaggeo.egu.eu)

Exposed are ancient rocks, heavily eroded by several glaciations and subsequent Holocene freeze-thaw cycles and snow melt flows. The location of the picture is on the west side of Norway’s mountain range. These mountains force western winds from the Atlantic upward, which makes the air cool down and release a lot of its moisture. The very frequent rains (we had 3 rain free days out of 16) create lush vegetation at lower altitudes (the tree line is between 600 and 700 m asl) and sustain extensive moss carpets higher up, as visible in the image. In places where the rock face is too steep to support moss, lichen covers it, which is evidence of very clean air – lichen are highly sensitive to air pollution.

The stream (and many similar streams nearby) feed a small lake that supplies Balestrand with drinking water. The lake can be reached in a day from Balestrand, but hiking further requires an overnight stay, even for most Norwegians, rugged as they may be. There are no huts or any other facilities, so you need to carry your camping gear with you. We camped a little higher without seeing anybody, and from the condition of the trails it was clear that everything beyond the reach of a day trip was used very infrequently. This unperturbed state, the abundant precipitation, and the inertious rocks made the water of the lake crystal clear (several meters of visibility) and very poor in nutrients (hardly any underwater vegetation), making it an excellent source of local drinking water.

In the composition, I liked the two halves of the snow arch mirroring each other, and the fact that the lines and the slope of the large exposed rock face are similar to those in the larger snow arch. The bright green of the moss upslope adds liveliness and draws the eye. I have a relatively simple camera (you want something light when backpacking) and at the time had no software to manipulate my pictures so I had to choose my viewpoint carefully and work with the light that was there. I scooped and stood very close to the snow to create a sense of perspective and have the arch reach over the camera.

By Gerrit de Rooij, Helmholtz Centre for Environmental Research – UFZ, Halle (Saale), Germany

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Imaggeo on Mondays: Trapped air

Can you imagine walking into the depths of an icy, white, long and cavernous channel within a thick glacier? That is exactly what Kay Helfricht did in 2012 to obtain this week’s Imaggeo on Mondays photograph.

Tellbreen Glacier is a small glacier (3.5Km long) in the vicinity of the Longyearbyen valley in the Svalbard region of Norway. Despite its limited size, it is an important glacier. One of the key parameters scientist use to understand how glaciers are affect by a warming climate is how the melt water is transported through to the front of the glacier. The majority of models utilise data from temperate or polythermal glaciers, i.e., glaciers which have free water within the icy matrix. Tellbreen is a cold glacier, meaning the basal layers of ice are frozen to the glacier bed; despite the traditional view that cold glaciers are not able to store, transport and release water, Baelun and Benn, 2011 found Tellbreen does this year round.

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Trapped air. (Credit: Kay Helfricht via imaggeo.egu.eu)

Kay visited Tellbreen whilst at the Artic Glaciology course at the University Centre in Svalbard. ‘Each weak one excursion led us to glaciers in the vicinity of Longyearbyen’ says Kay, ‘this day we visited the glacier Tellbreen. Near the tongue of the glacier the outlet of an englacial channel enabled us to explore the inside of the glacier. We went for some tens of meters into the channel.’

What the group found were that the walls of ice either side of the channel contained impurities, from stones to gravel, as well as mud and also water. The image above shows ‘air trapped in the ice-walls of the conduit at a time when the conduit would have been filled with meltwater of the glacier’ explains Kay. Air accumulated in bubbles at the roof of the conduit. When the water in the conduit started to refreeze along the side-walls, these smooth lenticular bubbles were trapped and stored in the ice. Studying the bubbles and other impurities in the ice can give hints on the history of the glaciers ice flow and its thermal regime over several decades.

References

Baelum. K., Benn. D.I.: Thermal structure and drainage system of a small valley glacier (Tellbreen, Svalbard), investigated by ground penetrating radar, The Cyosphere, 5, 139-149, 2011

Naegeli. K., Lovell. H., Zemp. M., Benn, I. The hydrological system of Tellbreen, a cold-based valley glacier on Svalbard, investigated by using a systematic glacio-speleologicalapproach, Geophysical Research Abstracts, 16, EGU2014-6149, 2014 (conference abstract)

 

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.