Cascades Field Trip: A Volcanic Blast!

Sept 30th: Dr. Helge Gonnermann’s Volcanic, Magmatic, and Hydrothermal Processes class set off dark and early Wednesday morning from Houston to the Cascades of California, Oregon, and Washington. We ventured across this varied volcanic terrain interpreting and learning about local and regional geologic events. The Cascades are an active continental volcanic arc resulting from the subduction of the Farallon plate beneath North America. Our first day consisted mostly of driving from Portland to Mt. Shasta and setting up at our lodging, a sweet house called Falconhurst (I still can’t get over the Bronte-ness of that name).

Oct 1st: Thursday, we drove through Mt. Shasta’s expansive debris flow deposits; these volcanic remains used to be mapped as glacial due to their poor sorting and extensive coverage. This is the largest subaerial debris flow on earth with an expanse of 450 km2. The huge hills we saw at every roadside stop were bits of ancestral Mt. Shasta’s flanks, deposited during the landslide 300,000-360,000 years ago.

Mt. Shasta and hummocks, pieces of its ancestral edifice deposited during a landslide.

 

Helge lectures on Mt. Shasta and debris flows

After dinner, several trip members were feeling peaky, so I made some medicinal grade ginger honey lemon maple tea, which was said to have “quite a kick”, and to be “reviving” (kind euphemisms for how spicy it was). The official recipe is as follows, but may be adjusted to taste.

Water                      1500 mL
Peeled ginger        150 g
Lemons                   2
Honey                    45 mL
Maple syrup         45 mL

Crush ginger and boil for 20 minutes. Squeeze lemons and strain into a jug. Add honey and syrup to your liking. (Personal notes: more ginger and longer boiling time results in a stronger, spicier brew.)

Nightly discussion featured vibrant political debate. Dr. Thomas Giachetti, who was Helge’s post-doc at Rice and is now a professor at the University of Oregon, joined us for dinner.

Oct 2nd: I awoke Friday morning to the dulcet tones of the smoke alarm wailing as the breakfast bacon burned. If you can’t handle thermodynamics, stay out of the kitchen! As we embarked, Sriparna noticed that every person in our car was from a different country (India, China, Iran, France, Brazil, USA), which I think is unique almost anywhere.

We hiked up Mount Lassen at Lassen Volcanic National Park. Lassen Peak is a dacitic dome, with pyroclastic dacite deposits containing phenocrysts and mafic enclaves, and dacitic pumice away from the peak. From the top, you can see Mount Shasta and the U shaped valleys carved out by glaciers in the last ice age.

View from Lassen Peak with Mt. Shasta in the background. Photo credit Thomas Giachetti.

View from Lassen Peak with Mt. Shasta in the background. Photo credit Thomas Giachetti.

Andesitic enclave within dacitic matrix at Lassen Peak

Andesitic enclave within dacitic matrix at Lassen Peak

We continued on to an a’a flow! I could hear the stratification of bubbles within the solidified flow as we trod over it, from the deep clunk of fragments of the dense inner core to the high-pitched glassy crunch of the sharp and vesicular upper crust. The flow had angular shards, round bubbly blobs, and solid dark fragments with visible feldspar phenocrysts.

At 8:15 pm we pulled the cars onto a side road on the way back to Mt. Shasta in the pitch dark to see the stars. The Milky Way was a full, bright arc directly above us, all the way across the sky. Satellites and shooting stars burned tiny white trails through the dark velvety firmament. I made a wish. It seemed impossible to take pictures of the sky, and we all decided it was best to experience the moment without needing to take it back home to show anyone else.

Oct 3rd: Our first stop Saturday was a basaltic pahoehoe and a’a lava flow, featuring a network of lava tubes. Flow direction was evident in the ropy pahoehoe sections by concentric surface flow features. Across the road was a scoria deposit; its clasts had smaller vesicles on the outside, smoothed from air fall, while their insides had larger bubbles where bubbles had enough time to coalesce.

Scoria airfall clast. Note the small vesicles on the outside (from airfall smoothing) and the larger ones inside (due to bubble consolidation).

Scoria airfall clast. Note the small vesicles on the outside (from airfall smoothing) and the larger ones inside (due to bubble consolidation).

We ate lunch at one of the highest points in the Medicine Lake volcanic area, with a great view of Little Glass Mountain (which is not so little) and Mt. Shasta’s head in the clouds. LGM is an effusive (non-explosive volcanic) obsidian rhyolite flow from 1000-1100 years ago. It is pancake-shaped with steep sides and a small dome in the middle near the vent.

Little Glass Mountain . Mt. Shasta in the clouds in the background. Photo credit: Thomas Giachetti.

Little Glass Mountain . Mt. Shasta in the clouds in the background. Photo credit: Thomas Giachetti.

Our next stop was Big Glass Mountain, another obsidian dome featuring glossy black volcanic glass banded with reticulite (a frothy, lace-like obsidian glass) in complex folds and beautiful flows. The banded textures are thought to result from magma exsolving dissolved gases; during eruption the shearing motion and pressure causes concentration of the gas in some layers but not others, or, alternately, shearing causes volatile exsolution and concentration. It was impossible to take enough pictures. We found beautiful folds that looked almost like fabric, and red layers intermingled with black obsidian. We discussed whether the reddish colors are iron oxidation, sericite from plagioclase microlite alteration, or some other alteration product.

Exsolution bubbles and textures at Big Glass Mountain, CA

Exsolution bubbles and textures at Big Glass Mountain, CA. Photo credit: Thomas Giachetti.

Josh with obsidian
My carmates were exceedingly kind about my eclectic music taste, with only minimal teasing about how ridiculously miscellaneous it is.

Oct 4th: Sunday morning we drove up to Portland via the magnificent volcanic Crater Lake and Mt. Mazama. The ash flow tuffs at the bottom of Mt. Mazama’s flanks are from the climactic eruption; their composition changes stratigraphically, indicating compositional changes of the magma chamber from which they erupted. This climactic event produced 40 times the eruptive volume of Mt. St. Helens. We estimated that the lake in the caldera could fit about 45 Rice campuses on its surface.

The layered flows on the cusp of the crater tell stories of the cataclysmic eruption. A red, weathered dacite lava flow on bottom is overlain by an orangey layered welded tuff flow, with a white pumice air fall deposit on top. Volcanic glass is not stable at atmosphere temperature and pressure, so it has begun to devitrify, crystallizing into spherulites over time.

Layered flow deposits on the rim of the Mazama caldera. Photo credit: Thomas Giachetti

Layered flow deposits on the rim of the Mazama caldera. Photo credit: Thomas Giachetti.

Volcanic glass alteration. Photo credit: Thomas Giachetti

Volcanic glass devitrification (spherulites). Photo credit: Thomas Giachetti.

Today in the car, while sharing music, we learned that the word ‘zindagi’ means life in both Hindi (जिंदगी) and Persian (زندگی). Persia and India have previously shared a border and continue to share culture, which persists in the language. Further north we began to see the Columbia River Flood Basalts, thick and hilly due to erosion, and golden from the grain fields covering each surface.

Columbia River Flood Basalts, eroded and with a splash of alpenglow.

Columbia River Flood Basalts, eroded and with a splash of alpenglow.

Oct 5th: Monday we had breakfast on the road; Helge told us stories of growing up on a farm in Germany with his favorite dairy calf, Sputnik.

We had uncommonly clear weather for our visit to Mount St. Helens. Small rock falls in the crater released bright dust clouds visible from kilometers away. Dr. Mike Poland, geophysical researcher for the USGS and expert on remote deformation measurement, was our guide. Mt. St. Helens is a member of the Cascades, famous for its catastrophic 1980 eruption. A cryptodome of pressurized magma began to build, pushing up the rock above it. When the rock above became gravitationally unstable, it fell, depressurizing the magma and causing the eruption and pyroclastic surge. All was quiet until 2004-2008 when a spine of hot crystalline rock, called the “whale back,” emerged within the crater.

As Dr. Poland discussed the things we can and cannot explain about eruptions, I’m struck again by a recurring thought of how young geology is as a science. People have been observing natural phenomena for millennia, but really understanding what they mean is an art. Seeing eruptive phenomena in person clarifies processes that are otherwise obfuscated by time or preservation bias. One can piece together that hummocks downhill of Mt. Shasta are pieces of the edifice, but until you see Mt. St. Helens erupt and move material in the same way, you can only guess. Geologists have time working both for and against us; eons are preserved in the rock record, but we only have our own perceptions, experiences, and conceptual limitations to guide us.

Mt. St. Helens. Slight dust visible at the top of MSH from gravitationally unstable rockfall.

Mt. St. Helens. Slight dust visible at the top of MSH from gravitationally unstable rockfall.

Our group in front of Mt. St. Helens with Dr. Mike Poland, who was kind enough to guide us. Photo credit: Thomas Giachetti.

I get the sense that losing volcanologists to volcanoes still stings. The way Mike and Helge reminisced about Dr. David Johnston, a geologist who died in the 1980 eruption, and Gerry Martin, the radio operator on the ridge behind him, there was a persistence of loss, and a solemnity underlying the oft-retold stories. Volcanology is scientifically fascinating, which draws us to it, but its dangers must be taken seriously. Sometimes curiosity comes at a price.

Thanks so much for a fantastic day, Mike!

Thanks so much for a fantastic day, Mike!

Monday night we ate at Beaches, a beach-themed (not Bette Midler themed?!) restaurant on the water in Portland. Our waitress was sweet and bubbly. At the end of our meal, she gave us saltwater taffy, and handed us packages of stick-on mustaches, telling us to get crazy and have fun. We took a group photo wearing them, and I think we all looked very distinguished.

Distinguished and also possessed. You CAN have it all! Photo credit: Julin Zhang

Distinguished and also possessed. You CAN have it all! Photo credit: Julin Zhang

Oct 6th: Tuesday morning we left the house at 4 am to get to the airport. When we all arrived home and unpacked, the TSA had searched each of our bags. I guess there’s something suspicious about carrying home pounds and pounds of rocks as souvenirs? This trip greatly expanded my understanding of volcanic processes, and was a wonderful experience overall.

Turkey Field Trip May 2015

Mw 8.3 September 16, 2015 Illapel, Chile Earthquake

On September 16, 2015, a magnitude 8.3 earthquake occurred offshore of Illapel, Chile along the interface between the subducting Nazca and overriding South America plates. Here I’ve used seismic data recorded in North America to image the source distribution of high-frequency energy radiated during this event using a method called back-projection.  The initial 60 seconds of the rupture propagates near the Chilean coast and is the likely source of strong ground shaking in the region.  In contrast, the second half of the rupture that propagates near the Peru-Chile trench likely generated the tsunami waves observed following this event.

Movie Caption: Warm colors represent high energy release at a given time (upper left corner).  The star is the epicenter of the event and the white dots are aftershocks on Sept. 16 and 17.  The white line is the coastline of Chile and the black line with white sawteeth is the Peru-Chile trench.

Working for the Government: Nisqually Wildlife Refuge 2015

This summer, I left the warm embrace of Houston and embarked to work for the U.S.G.S. as part of a Field Intensive Summer Internship program at the Nisqually National Wildlife Refuge in Olympia, Washington. For three months, I experienced life in the northwest, and even got to try my hand at being an ecologist.

The project I was hired on as a field technician for was called the “ESRP” project, which was just one of many many acronyms I became familiar with over my time at Nisqually. ESRP stands for Estuary Salmon Restoration Project. Nestled in the Puget Sound, just south of Seattle, the refuge was established after privately owned farm land, which had been diked off to enable crops and livestock to grow, was given to the government. Part of the dike was then removed, in order to allow for the estuary to reestablish and the native wildlife to repopulate the area! The refuge was full of beautiful migratory birds and otters and, in the delta, harbor seals and even dolphins.On the refuge, the U.S.G.S. was given the opportunity to track one of these species — the Chinook Salmon.

Partnering with the Nisqually Indian Tribe, the U.S.G.S. conducted field surveys of different aspects of the Chinook Salmon ecosystem. We collected benthic cores to sample some of the invertebrates contributing to the Chinook food source, we did Neuston Net towing in order to collect water column plankton, we tracked vegetation growth near water sources and set up fallout traps to catch the flies that were flying and dying, (this was the quantitative equivalent from which we could extrapolate the flies that were falling into the river feeding the estuary, which the Salmon could eat). The Nisqually Indian Tribe, who has exclusive rights to the harvesting and sale of adult Chinook salmon, took samples of juvenile Chinook. The point of the project was to comparing the contents of the juvenile fish guts and the bugs that we collected, and create a map of the feeding habitats and behaviors of the salmon.

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The field work was beautiful and a lot of fun. Most days our work on the estuary involved driving around a little Alumaweld boat loaded up with our sampling gear. Though I was around a bunch of ecologists all summer, I found out that they aren’t really that different from geologists (although I still maintain that geologists have more fun). And working as a field technician definitely has its perks. Not only do you get paid for being outside (every selfish scientist’s dreams!!) but the hours were flexible and we got to do everything in teams. Having a partner in anything makes it more meaningful, and a better learning experience, and about 20x more enjoyable. Most field technicians are usually bachelor-degree level, and scientists with a higher degree are the ones who are responsible for actually interpreting and preparing the information about the samples collected.

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My only regret of the summer is I didn’t get to focus much on the geology of the area I was working. However, I did highly value the chance to expand my comfort zone (moving to a new city where I didn’t know anybody and creating a community for myself there), being expected to come up with creative solutions to unexpected problems (such as dropping our equipment in the water and having to fish it out, or yanking out water level loggers from sediment-clogged PVC housing, or jerry-rigging a way to measure water volume flow, all the way down to having to wedge mouse traps in our trucks on the refuge to get rid of the infestation). I look forward to how this summer will prepare me for the long hours and personal sacrifices of grad school, or for working a job after graduation. Anybody who is interested in getting paid for field work should look into working for the U.S.G.S! Feel free to shoot me an email or ask me more if this sounds like something you’d like to hear more about!

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Cambrian Stromatolites in Central Texas – video!

Watch Andre Droxler and his students talk about their research on Cambrian stromatolites out in Central Texas!

Rice Earth Scientists at CIDER 2015 Summer Program

Several Rice Earth Scientists (PhD students Laura Carter, Shuo Ding, Michael Farner, and Lacey Pyle, post-doc Julia Ribiero, and Professor Helge Gonnermann) have just returned from the month-long CIDER workshop hosted at UC Berkeley in California. CIDER (Cooperative Institute for Dynamic Earth Research) is a FESD-funded grant tasked with the ambitious goals of: 1) providing an optimal environment for transformative studies requiring a concerted effort of leading researchers from different areas of Earth Sciences: high pressure material science, geodynamics, seismology, geochemistry and geomagnetism, and 2) educating a new generation of Earth scientists with breadth of competence across the disciplines contributing to understanding of the deep earth.

This summer’s theme was “Solid Earth Dynamics and Climate—Mantle Interactions with the Hydrosphere and Carbosphere,” (http://www.deep-earth.org/summer15.shtml) focusing on interactions between the mantle and the major surface reservoirs of water and carbon influence sea level, icesheet dynamics, the volume of the ocean, magma production, the volcanic flux of CO2 to the atmosphere, and the loss of carbon via subduction into the mantle. The first 2 weeks were lecture-based. Lectures were given by various renowned senior scientists in various disciplines from all over the world, with topics including solid Earth dynamics, ocean/glacial loading driving volcanism, paleoclimate models and sensitivity. In afternoon tutorials, we learned how to use various computational, laboratory, and field based tools, including ASPECT (convection software),  SEATREE (seismic tomography software), MELTS (melting/crystallization software), cheese deformation (hands-on lab about rheology, see picture with Shuo and Mike in the upper left corner), and CO2 diffusive degassing (in-the-field measuring with CO2 IR sensor). The last 2 weeks we were broken up into student-run groups, each focusing on a different research question relating to what we’d learned in the first 2 weeks. Shuo was part of a group investigating the transport of carbon between atmosphere/ocean and the Earth’s interior in the Archean, Laura and Lacey calculated CO2 fluxes in the Eocene to explain anomalous global temperature curves, Mike and Helge explored the effects of glacial melting on Mount Mazama eruptions, and Julia looked into the fate of water in bend faulting during subduction.

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We all thoroughly enjoyed our experience. We learned a lot about various aspects and in diverse disciplines within Earth Science, and networked with colleagues and well-established senior scientists. We presented our own research in poster sessions, and look forward to continuing collaborations started with CIDER projects. California was also a beautiful location, and many of us took advantage of the local mountains and ocean on the weekend, for example hiking at Yosemite National Park (see picture with Laura Carter and Lacey Pyle).

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Students in the Rice Earth Science department have a long-running tradition of attending this workshop each year. If interested, you can find more information about the fully-funded summer 2016 program, titled Flow in the Deep Earth at http://www.deep-earth.org/summer16.shtml  (applications end February 1, 2016). Additionally, CIDER hosts a 1-day pre-AGU workshop where summer 2015 participants will present their projects, and invited speakers will introduce the theme for summer 2016 (sign up to attend here: http://www.deep-earth.org/preagu2015.shtml).

Uranium, dinosaur bones and agates in the Western Interior Seaway

ESCI 322 – Going Across Southern California

Mafic enclaves in the Bernasconi Hills Pluton in southern California. Emily Pain for scale.

Mafic enclaves in the Bernasconi Hills Pluton in southern California. Emily Paine for scale.

Students in 322 go on a geology trip across southern California led by their professor Cin-Ty Lee and graduate student Hehe Jiang.  This is a mid-term field trip that the department has used to give a students a chance to apply some of their classroom knowledge to the field.  When it comes to looking at rocks and minerals, there is nothing better than going to the field where one has context.  It makes learning about rocks much more meaningful and more memorable. 

So this year, the class did a transect across southern California.  We arrived Friday afternoon in Ontario, California.  Our first stop was in the northern Peninsular Ranges Batholith, part of a continental volcanic arc that extended from Mexico all the way up through Canada during the Cretaceous.  This volcanic arc would form the backbone for much of our trip, so-to-speak.  We visited the Bernasconi Hills pluton, where we examined outcrops showing extensive mafic-felsic mingling in the form of mafic xenolith swarms and highly attenuated schlieren.  We then made our way across the San Jacinto Valley, a late Miocene-Pliocene graben formed by extension in the vicinity of the San Jacinto Fault, a splay of the San Andreas Fault. Around us, rising above the valley floor were large knobs of Cretaceous granitoids.  We made our way down to Green Acres, where we had a chance to examine olivine-gabbros, examples of cumulates in a shallow mafic magma chamber. 

We found ourselves the next morning in San Diego.  After a quick breakfast at McDonald’s, we headed out to Point Loma to examine the Point Loma and Cabrillo formations.  We picked the perfect place to look at these outcrops because we were right along the ocean, with waves crashing, sea gulls squawking, pelicans diving and the cool breeze blowing against us.  These are late Cretaceous sediments. We examined them under our hand lens and discovered that they consisted of quartz, feldspars, and lots of fresh biotite and hornblende. Normally, biotite and hornblende don’t last long in the weathering regime, so their presence suggests a very juvenile sediment.  These sediments, it turns out, were being shed off the Cretaceous volcanic arc, most likely while the arc was still active, given its age.  Yesterday, we were looking at the eroded plutons and today, we are seeing their eroded tops in an ancient basin!

Cretaceous fore-arc sediments at Point Loma, California.

Cretaceous fore-arc sediments at Point Loma, California.

It was hard to pry ourselves from the ocean, but we had to because we a schedule to stay on.  Our goal was to head east.  On the way, we stopped by some Eocene forearc sediments exposed in a roadcut. These sediments were completely devoid of biotite and hornblende and were formed by the erosion of deeply weathered surfaces of the batholith, well after magmatism and mountain building had ended.  A few of the students found some shell fossils in the sediments, indicating a shallow marine origin.  After our brief foray into the Eocene, our drive along I-8 took us back into the Cretaceous plutons.  We turned north to Cuyama Valley, where we looked at more olivine-gabbro cumulates along the shore of Lake Cuyama. But our excitement quickly turned to a large area of exposed migmatites.  Here, the metasediments had been metamorphosed, deformed, and recrystallized to such a degree that they looked like a gneiss and in some cases looked like a highly foliated granite, but the tell-tale signs of migmatization were the abundant quartz- and feldspar-rich veins and dikes that appear to have formed during ductile deformation.  This was the birth place of some of the granites that contributed to the Cretaceous batholith.  There were a lot of mortar holes on the outcrop, left behind by Native Americans. How nice it must have been to grind food on migmatites!

Lunch

Lunch

Our next stop on Saturday was high up in the San Jacinto Mountains, just above Palm Springs. We stopped specifically at the top of Deep Canyon, where if one looked south, we could see a large dip slope composed of late Cretaceous mylontinized granites and tonalites.  We crawled all over the mylonites in search of two things: pseudotachylites and titanites.  Pseudotachylites are melts of the rock generated by intense frictional heating during an earthquake.  These melts were everywhere, some in foliation and many crosscutting.  The titanites, aka sphene, were large pistachio-green porphyroblasts formed during ductile deformation.   All of these deformational features are associated in intra-arc thrusting and exhumation during the late Cretaceous and early Paleogene.  Our day was soon coming to an end.  We descended into the Coachella Valley, but not before stopping at a vista point to look at the San Andreas Fault and the Salton Sea.  We ended our day in Palm Desert with a big Italian dinner!

We started Sunday morning with some unfortunate news. One of our students had his camera bag, tootbrush, and some clothes stolen out of his room, which had been inadvertently left slightly ajar in the chaos of organizing 18 students.  We spent several hours searching for the bag, looking at security videos, and calling the police, but deep down, we knew that we weren’t going to see his bag again. The good thing, if there was a good thing, was that he still had his wallet and identification.  So we moved on, but being a few hours behind, we decided to skip some of the stops.  We ended up driving down the west side of the Salton Sea, stopping briefly at North Shores to touch the sea and to talk about the opening of the Gulf of California.  The sea keeps receding each year as water supplies to agriculture have been steadily declining, so each year, we seem to have to walk further out across the barnacle beach to reach the water. 

After we got our fix of dead fish, we drove another hour south and found ourselves at the mud volcanoes.  The high water table and high heat flow here is what causes these mud volcanoes to form. Geothermal power plants have taken advantage of this combination.  The mud volcanoes gave us an analog for many of the different volcanoes and lava flows we talked about in class: spatter cones, pahoehoe, aa, etc.  It was great to see some of these mud volcano eruptions in action!  Our next stop was Obsidian Butte, a Pleistocene rhyolitic lava flowwhich generated a large obsidian dome.  We marveled at all the beautiful flow banding and we discussed why obsidian flows tend to be big blobs rather than long, thin lava flows. Viscosity!

Talking about mud volcanoes in the Salton Sea. Emily Paine, Detao He, Cin-Ty Lee, Josh Crozier.

Talking about mud volcanoes in the Salton Sea. Emily Paine, Detao He, Cin-Ty Lee, Josh Crozier.

The rest of the day was spent getting from the Salton Sea into the Mojave Desert.  We stopped briefly at Salt Creek, where we crossed over the railroad tracks to look at the San Andreas Fault up close and personal.  Unfortunately, while we were on the other side, the longest train in the world came up and decided to park itself there.  We decided it was too dangerous for us to climb through the train back to our cars as there was no telling when the train might start up again.  The only way was to go around or, in this case, we knew there was a bridge we could go under, but the bridge was quite a ways to the north. Should we wait or walk? We had no idea how long the train was going to stay, so we decided to do the long hike.  By the time we got back to our cars, delayed by an additional hour, the train still had not moved, so it was a good decision. 

Re-energizing with a good dose of fluids, we drove up out of the Salton trough, crossing the San Andreas Fault to the north and passing through Pliocene deltaic sediments, variably deformed and tilted.  We stopped here to look at a wonderful assortment of textbook sedimentary structures (sorting, cross-bedding, soles, soft-sediment deformation), and then further up the canyon, we found the contact between these sediments and the basement, only here the basement was a new rock for the trip – Pelona greenschists associated with subducted sediments or basaltic crust during the Cretaceous.  We ended our long Sunday trip in Joshua Tree National Park, with the students climbing up and down the giant quartz monzonite boulders.

On top of a boulder in Joshua Tree National Park. L to R: Detaho He, Michale Farner, Evan Neustater, Kate Nicholson, Elizabeth Finlay.

On top of a boulder in Joshua Tree National Park. L to R: Detaho He, Michale Farner, Evan Neustater, Kate Nicholson, Elizabeth Finlay.

students examining pebble lag deposits in the Mecca Hills. Yunong Xu, Beineng Zhang, Stephanie Zou, Farah Ashraf.

students examining pebble lag deposits in the Mecca Hills. Yunong Xu, Beineng Zhang, Stephanie Zou, Farah Ashraf.

Monday would be our last day out in the field.  Our first stop would be Amboy Crater in the Mojave Desert on the North American plate. This was our opportunity to discuss why basaltic lava flows can flow much further than rhyolitic flows. Close inspection of the lava flows revealed tiny euhedral crystals of olivine and lots of vesicles! Off in the distance, we could see a pristine cinder cone.  This must have been quite the sight when it was erupting.  After our Amboy Crater stop, our goals were to look for xenoliths at Dish Hill and then trilobites in the Marble Mountains, but due to all the rains and flash floods that had happened earlier in the season, the highways were all closed.  We had no choice but to change our plans on the fly.  Our professor, Cin-Ty, decided then to try a place he had never been to before.  Off in the distance, one could see limestones jutting up against some granitic basement, so we parked our cars and walked across the alluvial plain.  We had no idea what to expect, so we were told to fan out and just explore.  With 18 pairs of eyes, we were bound to see something, and soon, students were coming up with little fragments of Vesuvianite, a clear indicator mineral for skarns!  But where was the actual skarn?  So we fanned out again, falling the trail of bread crumbs and looking around for the contact.  And there it was, all the vesuvianite was forming right up against the contact!

Vesuvianite with Elizabeth Finlay and Sarah Gerenday

Vesuvianite with Elizabeth Finlay and Sarah Gerenday

With our pockets filled with new minerals, we continued north, deep into the Mojave.  We stopped briefly at the Kelso Sand Dunes and then had lunch at the Kelso train depot, a nice green spot in the middle of the desert.  We then headed to the Cima Volcanic field, where there are numerous cones, all erupted in the Late Miocene to present.  We stopped at well-known but difficult to find lava tubes, and then we drove a little further up a rough road to look for xenoliths. Normally, we don’t do this latter part because the road is so rough, but since our plans at Dish Hill were diverted, we thought it would be a nice way to end the trip.  Unfortunately, the road became far too rough to continue further, so we hiked the last stretch.  And xenoliths we did find!  Peridotites everywhere!

Hunting xenoliths in Cima. L to R: Cin-Ty Lee (hideen), Evan Neustater, Kate Nicholson, Yunong Xu, Farah Ashraf.

Hunting xenoliths in Cima. L to R: Cin-Ty Lee (hideen), Evan Neustater, Kate Nicholson, Yunong Xu, Farah Ashraf.

Our luck, however, would not hold out.  As we turned our cars around and headed back down the slope, one of our cars hit a rock hard, twisting its axle. Definitely not good because it made it hard to drive.  What to do now?  The sun had set, the students were tired and hungry, and we had early flights out the next morning, but all the way back in Ontario, a three hour drive with a good car.  We convened at the Mad Greek in Baker and it was decided that the everyone would pile into the other working cars and just go back to Ontario so they could get a good night’s sleep.  Our professor and a couple of visiting grad students would drive the disabled vehicle back, slowly.   It took the five hours and a tire blow out in the last 20 miles, but they arrived home safely.

Earth Science ESCI 334 Field Trip

2015-March-ESCI334-NMESCI 334 is one of the Earth Science department’s capstone undergraduate courses. The field trip takes us to a location near San Ysidro, New Mexico, because of the easy access to phenomenal rock exposures, which span approximately one billion years of geological time. Students map in detail rocks that were folded and faulted during the late Cretaceous Period (approximately 70 million years ago), as a consequence of the intense mountain building along the western margin of North America during that time.

During the field campaign, students integrate and apply knowledge they acquired throughout their undergraduate earth science core curriculum. The goal is for students to achieve their full potential in exploring and discovering the geology underfoot. Throughout the field trip students build their confidence in working independently. They make their own scientific observations, which culminate in an interpretive report that transforms their observations into geological understanding.

During the field trip students form bonds and friendships with one another that often extend beyond their studies at Rice. This sort of camaraderie and friendship is in part facilitated by our lodging arrangement. This year the group of students was rather large, but we were able to find a vacation rental on the outskirts of Albuquerque, which had two houses on a single property. Although quarters were tight, this allowed us to share meals and socialize in the evenings, after a hard day’s work in the field.

RUGS Students Visit 1 Billion-year-old Serpentinite

2015-Feb21-RUGS-Serpentine

1 Gy serpentinite. From left to right: Elli Ronay, Xun Yu, Detao He (behind Xun), Larisa LaMere, Sriparna Saha, Michael Farner, Lexi Malouta, Rachel Marzen, Jackie Rios, Adeen Denton, Tierra Moore, Emily Paine, and Cin-Ty Lee (taking the picture!).

How do you get water back into the mantle?  Serpentinites, of course!  The main source of water in magmatic arcs like the Cascades comes from altered oceanic lithosphere.  Interaction of the seafloor results in extensive hydration of the crust and lithospheric mantle, resulting in the conversion of olivine-rich rocks (peridotite) to a green phyllosilicate-bearing rock known as serpentinite.  Studying serpentinites is the key to understanding the global water cycle, at least on million year timescales. What were subduction zones like billions of years ago?  There are many examples of Phanerozoic serpentinites, but really old serpentinites are rare.  It turns out that we have some ancient serpentinites right here in Texas, in the one billion year Grenvillian orogenic belt that cuts across our state.

Green, green olivine
Peridot is when you’re on show.
Drops of water,
Sooner or later,
You become serpentine.

So the Rice Undergraduate Geology Society (RUGS) organized a one day trip out to central Texas today to look at these 1 billion year old serpentinites. We started out at 6 am in the morning and hightailed out to the Coal Creek serpentinite. We met one of our professors Cin-Ty Lee out there – he had arrived several hours earlier to search for a rare Mexican bird called a Striped Sparrow. A couple of faculty from UT Austin also joined us. The day turned out to crystal clear, with mild temperatures. We could not have asked for a better day weather-wise.


We arrived at the serpentinite outcrop. We immediately noticed that the quarried sections were light green, but the weathered surfaces were red, a common feature of ultramafic terranes. There was almost no vegetation growing on the serpentinite surfaces, in stark contrast to the surrounding amphibolite rocks, which had small live oaks growing on them. We spent a couple hours scrambling over the quarry, trying not to roll our ankles, all the while pondering what type of peridotite protolith this was. Was it oceanic lithosphere, fore-arc lithosphere, sub-arc lithosphere, or back-arc lithosphere? How would we tell? Does the serpentinite represent a suture between the collision of two continents? What we all agreed upon was that this serpentinite looked old! No hints of fresh olivine anywhere, but everywhere, there were hints of serpentinizing fluids in the form of syndeformation veins. We also found a couple of local samples that appeared as if they were originally troctolites based on relic cumulate texture.

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Serpentinites with magnetite-rich veins


After having lunch on these green rocks, we decided to head to Enchanted Rock to look at granites up close and personal. Unfortunately, when we arrived, the park had reached its capacity for the day and they were not letting in anymore visitors until 3 PM. So we went back towards where we had just come from and stopped to look at an unconformity where Proterozoic granites and migmatites were overlain by Paleozoic limestones. A hundred million years missing beneath our feet! We spent a half hour crawling over some beautiful exposed migmatites and discussed what conditions are needed to melt the lower crust.

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Syn-magmatic diking in migmatite


Daylight was running out, so we thought we would take one more shot at getting into Enchanted Rock State Park. We arrived there with only about 2 hours left of sunlight and a long line of cars inching their way through the entrance. We eventually got in with enough time to climb to the top of one of the granite domes. It was a nice way to end the day! Participants (see our group shot above) included from left to right: Elli Ronay, Xun Yu, Detao He (behind Xun), Larisa LaMere, Sriparna Saha, Michael Farner, Lexi Malouta, Rachel Marzen, Jackie Rios, Adeen Denton, Tierra Moore, Emily Paine, and Cin-Ty Lee (taking the picture!).

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running up Enchanted rock.