In August 2023, a group of 13 iMAGE-CREATE students, along with instructors Dr. Brian Cousens and Dr. Erin Bethell, travelled to Iceland for a 9-day field course. The unique geological setting of Iceland, which is the largest land exposure of the Mid-Atlantic Ridge and current centre of the Iceland Mantle Plume, provides an excellent location to study geodynamic processes operating on the seafloor. The course included stops in the Reykjavik area, south coast, Snæfellsnes Peninsula, and north Iceland (in the vicinity of Lake Mývatn), focusing on modern volcanic and hydrothermal systems.
In addition to the field experience, students were tasked with completing a pre-trip remote predictive mapping project for the inaugural iMAGE-CREATE Terrane Mapping School. Each student used a variety of remotely sensed datasets to produce a 1:100,000 scale geological map of their assigned map area. Each map area corresponded to a location visited in the field, providing the students with a unique opportunity to ground-truth their remote predictive maps. Students gave in-field presentations on their maps, allowing them to integrate the knowledge gained from both remote and field observations.
Included below is a day-by-day summary of the in-field portion course, written by the student attendees.
Wednesday August 9th: Golden Circle Tour
Part 1 – Kerið crater, Gullfoss waterfall (written by Sarah Moriarty)
Our first stop of the trip was to Kerið Crater, which is a crater-lake containing volcanic structure located in Southwest Iceland. The dominant rock type noted by the iMAGE-CREATE group at Kerið Crater was a reddish vesicular, glassy basalt seemingly indicative of explosivity and splatter. It was therefore inferred by the group that the crater was phreatomagmatic, having formed via volcanic explosivity and potentially later geothermal activity. However, the diagrams at the entrance to Kerið Crater suggested that rather than explosivity, the crater formed via emptying of the magma chamber, leading to the inward collapse of the volcanic structure, thereby making Kerið Crater technically a caldera.
Later, we went to Gullfoss, which is a major two-step waterfall located in the Hvítá river canyon, also in Southwest Iceland, sourcing its water from the glacier Langjökull. The two distinctive step-like ledges of Gullfoss are formed by lava flows that are relatively water erosion resistant compared to the other more erosion prone sedimentary lithologies at the site.
Thursday August 10th: Reykjavik to South Coast
Lava and Earthquake Centre, Skogafoss waterfall (written by Ysabèle Rivard)
On August 10th, 2023, participants of the Iceland field course embarked on an educational and awe-inspiring journey that included two remarkable stops: The Lava and Earthquake Centre and the iconic Skogafoss waterfall. The day began with a visit to The Lava and Earthquake Centre, a hub of geological discovery nestled in the heart of Iceland’s volcanic landscape. Here, we were treated to a deep dive into Iceland’s unique geological history and its profound influence on the island’s character.
Inside the Lava and Earthquake Centre, interactive exhibits illuminated the dynamic forces that have shaped Iceland over millennia. We were awed by simulations of volcanic eruptions and earthquakes, offering a visceral sense of the island’s geologic volatility. We learned about plate tectonics and the Mid-Atlantic Ridge, the geological processes responsible for Iceland’s dramatic landscape. The center’s comprehensive displays, multimedia presentations, and knowledgeable guides wove a narrative of Earth’s tectonic processes that unfolded right beneath our feet.
Armed with newfound knowledge, the group continued their adventure to Skogafoss waterfall, where we marveled at the synergy between geological forces and natural beauty. The Lava and Earthquake Centre’s immersive experience served as an enlightening prologue to the wonders of Iceland’s landscapes, making this field course an enriching blend of education and adventure that left lasting impressions on all who attended.
Part 2 – Geysir geothermal field and Þingvellir National Park (written by Jennifer Spalding)
The second half of the classic Golden Circle Tour comprised of visiting Þingvellir National Park, where part of the Atlantic’s mid ocean ridge (MOR) is exposed. Sub-aerial exposure of the MOR is facilitated from buoyancy related to Icelands underlying mantle plume. Þingvellir lies at the triple junction between the Western Volcanic Zone (WVZ), the South Islandic Seismic Zone (SISZ) and Reykjavik Peninsula Oblique Rift (RPOR).
Entering the National Park, the road descends into a steep valley that represents the eastern boundary of the North American tectonic plate and the cliff-faces on the opposing side expose the western margin of the European plate. The park’s main trail consists of a wooden boardwalk through a narrow valley bound by sub-vertical rock faces, representing an extinct rift axis. Meltwater from the nearby Langjökull glacier infiltrates the volcanic rocks and fill deep fractures to form several ravines.
At least five basaltic flows are preserved in Þingvellir. The oldest flow preserved is from the Eemian (interglacial) period, followed by the Weichselian (interglacial) period, that formed characteristic supra-glacial table-top mountains contoured by hyaloclastites at lower elevation, representing their sub-glacial counterparts. These flows are crosscut my olivine tholeiites related to the Skjaldbreiður shield volcano (~9500 y.a) located ~20 km to the NE at an elevation of 1060 m. Subsequent eruptions during the Holocene comprise of Elborgir lava flows, preserved as a NE-SW trending chain of densely spaced craters and characteristic hyaloclastite ridges. Cross-cutting the Elborgir flow are Þjófahraun flows, that also form a NE-SW row of craters. The extent of the flow is dictated by paleo-topography, as they fill the valleys between the hyaloclastite ridges from Elborgir. Crystallization ages from the volcanic rocks in Þingvellir are too young to be dated via traditional radiometric ages. Instead, the timing of volcanism is constrained 14C dating of vegetation preserved at the base of flows.
Iceland is migrating NW relative to its underlying mantle plume, although, the plume is believed to facilitate rifting by crustal weakening. The rift-jump model suggests the Eastern Volcanic Zone (EVZ; located east of the WVZ), represents a new rift axis that overlies the current position of the plume. Stress transfer is evinced by seismicity in the SISZ, which connects the WVS to the EVS (e.g. M=6.6 earthquake in 2000). It is believed that rifting along the WVZ is dying out and will be overtaken by rifting in the ESZ. Volcanism and stress-transfer processes observed in the Þingvellir area serves as an analogue to understand MOR processes that are elsewhere submerged.
Friday August 11th: South Coast
Part 1 – Pakgil lookout over Katla volcanic complex, Hjörleifshöfði tuff cone (written by Jonathan Umbsaar)
Pakgil Lookout: While on route from our previous night’s stay, we stopped at an outlook to read some local infographics about some of the features we were driving over. Low-hanging cloud cover obscured the highlands and Eyjafjallajökull glacier, but the outwash plain from Katla was clearly visible, and evidently very extensive.
The Katla volcano has experienced a series of sub-glacial eruptions, wherein volcanic output is rapidly quenched by the cold glacial cap. The result is a pervasive output of dark black, glassy sediment and ash that is deposited in an outwash plain of deltaic streams. Large pulses of volcanic activity have the capacity to extend the shoreline by several kilometers, as the vast volumes of volcanic sediment are transported to the margins of the island.
Hjörleifshöfði Tuff Cone: This volcanic feature exists on the margins of Iceland, near the ocean, and surrounded by the outwash of volcaniclastic material from the Katla Volcanic Complex. This volcanic mound is composed of steeply dipping beds of poorly-sorted volcanic breccia, with dominant clasts being aphyric basalt and some jointed blocks of basalt. The rock is matrix supported, and is composed of roughly 70-75% matrix material that is dominated by ash and lapilli.
This volcano likely represents a submarine cinder cone which previously erupted beyond the shoreline, but was engulfed by Katla sediment output, creating a phreatomagmatic volcanic feature.
As a group, we wandered inside a cave structure to observe the volcaniclastic features, and to escape from the downpour of rain. Beyond the tuff cone, a flat plain of black outwash sediment derived from Katla extended in all directions.
Part 2 – Eldgja rootless cones, Reynisfjara beach (written by Charles Lapointe)
On August 11th, the group made a stop at one of several rootless cone fields in the Eldgja volcano area resulting from the Eldgja fissure eruption of 934-940 AD. One of the most voluminous eruptions known to have occurred on Earth, it produced just under 20 km3 of lava. The area lies within the East Volcanic Zone of Southern Iceland, one of the most active volcanic areas on Earth (Thordarson & Larson, 2007); indeed, the nearby Laki fissure eruption of 1783-1784 was also exceptionally large, producing nearly 15 km3 of lava (Hamilton et al., 2010a).
Rootless cones are a rare volcanic feature which may occur when a voluminous lava flows over an area of wetlands. The surface of any lava flow cools and solidifies quickly, forming a crust which insulates and seals the rest of the flow, preventing effective degassing. The presence of water leads to vigorous vaporization and overpressure within the advancing flow, resulting in steam explosions. The flow top is breached and lava spatter is ejected, landing atop the solidifying flow and forming a tephra cone. At Eldgja, these cones are almost entirely composed of basaltic spatter, but also contain traces of rhyolitic melt which may have been sourced from the fractional crystallization of a very high fraction of basaltic melt (99%). These are found as centimeter-scale obsidian within basaltic spatter, the high viscosity of rhyolite preventing further mixing and maintaining the rounded shape of the rhyolite bubbles.
In the afternoon, the group visited the famous Reynisfjara black sand beach, which consists of volcanic ash-derived black sand and small pebbles. The beach lies at the foot of the steep sided Reynisfjall mountain, with the impressive Reynisdrangar basalt stacks just off the shore. The slope of Reynisfjall consists of spectacular and varied columnar basalts produced by large lava flows as well as dike intrusions. The group marveled at the many examples of columnar jointing readily observed at the site, while a colony of Atlantic puffins nested atop the many basalt stacks just overhead.
Saturday August 12th: Hekla to Snæfellsnes Peninsula
Hekla volcano lookout and pumice quarry, Gerduberg cliffs (written by Sheila Ballantyne)
On the fifth day of our Icelandic adventure, we travelled north from the town of Vik towards the infamous volcano, Hekla. Known since the Middle Ages as the “Gateway to Hell”, Hekla is a dangerous stratovolcano, erupting frequently with little to no warning and burying the region in ash, tephra, and poisonous levels of fluorine. The 1.4km tall volcano has a unique elongated stratovolcano shape, often compared to an overturned boat. Thanks to great weather and clear skies we frequently had excellent views of Hekla throughout our time touring the southern parts of Iceland. On our first stop this day we stood approximately 10km north of Hekla, amid ~5m deep active pumice quarries exploiting the abundant Hekla tephra deposits. In one quarry, the group observed a layer of black organic material buried by 10-20cm of white, angular tephra. This organic layer may represent the time leading up to the year 1104, when farming flourished in the region for generations before being buried by 1km3 of pumice, preserving the local longhouses and archaeological items of Iceland’s early settlers.
The group learned at the Lava Centre (on August 10) that Hekla is situated where the South Iceland Seismic Zone (SISZ) and Eastern Volcanic Zone (EVZ) meet, at a rift-transform junction. Rifting in Iceland is partitioned, with the Reykjanes Ridge entering the country in the southwest, then jumping towards the east to take advantage of the mantle plume below the centre-east of the island. The SISZ accommodates this left-lateral transfer of rifting with a series of bookshelf faults. Hekla is sited at the western edge of the SISZ and eastern edge of EVS, with the deep ridge-transform faults and associated fissures tapping the magma sources below. The petrology of Hekla is unique with intermediate and felsic eruptions common, creating dangerously explosive events with virtually no pre-eruptive seismic activity. A positive correlation has been well documented between quiescence of Hekla and the silica content and volume of tephra of an eruptive event. The most destructive recorded eruption in 1104 occurred after more than 250 years of dormancy. Hekla last erupted in 2000.
We drove west and then north from the pumice quarries, with views of the west coast of Iceland as we approached Snæfellsnes Volcano. We arrived late in the afternoon at Gerðuberg cliffs, an awesome 500m long, 14m tall wall of perfect columnar jointed basalt. This flow erupted from nearby Ljósufjöll volcano, part of the Snæfellsnes volcanic system. The columns are remarkably uniform, each ~1.5m in diameter with nearly perfect hexagonal shape, suggesting rapid cooling likely associated with a wet environment such as a marsh. The basalt is coarse, with abundant phenocrysts of olivine and plagioclase, and undeformed vesicles throughout. Chisel marks create horizontal lines along the sides of the columns spaced 5-10cm apart, with spacing smaller towards the top of the flow. Looking to the north and east from the cliffs, the group observed red-oxidised spatter cones, a preview of the craters the group visited on the following day.
I finished my day bird-watching on the beach near our guesthouse, with views of the ice-covered Snæfellsnes to the north and the cold northern Atlantic ocean.
Sunday August 13th: Snæfellsnes Peninsula
Part 1 – Eldborg spatter cone, Kirkjufell mountain, Snæfellsjökull volcano lookout (written by Dan Stepner)
The morning of day 6 began with a short drive to Snorrastaðir Farm where we hiked over lava fields towards the Eldborg Crater spatter cone, a ~60 m tall volcano which erupted 5000-8000 years ago now rises above the surrounding farmland. Once the whole group reached the top, we investigated how the morphology of lava changed during the eruption and where evidence of the lava lake spilling over the top of the cone has been preserved.
Our next stop was next to Kirkjufell Mountain, a rare occurrence where glacial sediments and sedimentary rocks are preserved within this volcanic landscape. This mountain captured everyone’s attention and one participant was quick to point out that it is famous as “Arrow Head Mountain” on Game of Thrones. Instead of climbing to the top, the group walked to the nearby Kirkjufellsfoss waterfall where everyone was able to snap a great photo with the mountain in the background.
Continuing along the highway we briefly stopped at a viewpoint for Snaefellsjojull, the glacial capped stratovolcano which dominates the western parts of the Snæfellsnes peninsula. A group photo was quickly arranged before we continued on our way.
Part 2 – Saxhóll scoria cone, Hólahólar crater, Arnarstapi cliffs, Búðahraun lava fields lookout (written by Quan Zhang)
In the sixth day of our Iceland volcanology course, we embarked on an exciting journey through some of the most intriguing geological sites in the Snæfellsnes Peninsula. The Saxhóll crater is a remarkable feature that produced dense basaltic scoria and tephra, rich in olivine, plagioclase, and titanomagnetite phenocrysts. Ascending the walking trail to the top of the cone rewarded us with breathtaking panoramic views, offering a firsthand look at the forces of volcanic activity that shaped this landscape.
Next, we explored the Hólahólar craters, a cluster of craters, with one particularly accessible site allowing us to drive right into the crater itself. The Berudalur crater presented an amphitheatre-like opening, showcasing the dramatic aftermath of volcanic eruptions. As we ventured further, our journey along the Snæfellsnes peninsula revealed the Arnarstapi cliffs, adorned with impressive basalt columns and colonies of seabirds. Here, we learned about the legendary settler Bárður, who played a significant role in the area’s history, and marveled at the volcanic mountain, Stapafell, with its towering presence. Lastly, we stood in awe at the Búðahraun lava fields, remnants of the ancient Búðaklettur volcano, and explored the remarkable caves within the pahoehoe lava formations. These lava fields offered insights into MgO-rich alkaline basalts with distinctive tri-porphyritic characteristics, showcasing the diverse geological wonders of Iceland’s volcanic past.
Monday August 14th: Snæfellsnes Peninsula to Lake Mývatn
Grábrók crater, northwest Iceland geology (written by David Summer)
On Day 6 of the Iceland field course, we visited the Grábrók crater, east of the Snæfellsnes Peninsula. The Grábrók crater is the larger of three craters located at the eastern termination of a 90 km long lineament of volcanoes called the Ljósufjöll system, trending ~110° from the Snæfellsnes Peninsula. The crater is a basaltic spatter cone that erupted along a crustal fissure ~3000 years ago. Breaching of the cone resulted in basaltic flows infilling portions of a nearby river valley. The Grábrók eruption and other related volcanics occur over top of Tertiary basalts that likely formed during NW-SE-directed axial spreading as indicated by prominent glacially exposed NE-SW trending lineaments (fault scarps). Two other volcanic lineaments occur to the south of the Ljósufjöll lineament, together comprising the Snæfellsnes Volcanic Belt (SVB).
The SVB is itself an off-axis system of volcanism. The origin of the of the SVB relates to mid-ocean ridge (MOR) migration over the Iceland hotspot and a subsequent ridge jump. As Iceland formed over the hotspot, the Western Volcanic Belt (WVB) was the subaerial extension of the mid-Atlantic ridge. Throughout the Miocene, the mid-Atlantic ridge migrated westward along with the North American plate. Today, the Iceland hotspot is positioned beneath the eastern part of Iceland. Because of the thermal weakness induced by the hotspot, a ridge jump has caused the formation of the Eastern Volcanic Belt (EVB) and its northern extension, the Northern Volcanic Belt (NVB). The WVB is still active south of the Mid Iceland Belt (MIB), which connects the WVB to the EVB and NVB. North of the MIB, the WVB is inactive. South of the MIB, the cumulative spreading of the WVB and the EVB exceeds that of the spreading along the NVB. The differential spreading rates resulted in the tectonic forcings that reactivated relict fracture zones in the SVB. The SVB, therefore, is a series of transform faults that accommodate dextral motion between northern and southern Iceland.
Tuesday August 15th: Lake Mývatn
Part 1 – Stakholstjorn rootless cones, Dimmuborgir lava complex (written by Martina Boddy)
To kick off the morning of August 15th, we travelled to the Stakholstjorn rootless cones located in the Lake Mývatn locality. At this first stop we realized what mývatn meant in English – gnat! With our bug nets on, we hiked through the second rootless cone field seen on the trip. In contrast to the Eldga rootless cones, these cones were considerably bigger (appearing more like scoria cones) and were composed of smaller lapilli sized fragments. The size of the tephra indicated that this rootless cone field would have formed from a less viscous or more gaseous lava than the lava flow that produced the Eldga field. Unique to the Stakholstjorn cones, an intact piece of root was found near the lake. This large root was ropey, very glassy and had holes, believed to be evidence of bubble conduits. Before leaving the cone field, we stopped into the visitor centre to learn more about what this rootless cone field could tell us about magma generation on other planets, and under the sea.
After a short drive, we arrived at the second stop, the Dimmuborgum lava complex. This complex is an interesting geological and historical site. From the overview, we discussed the tall lava spires visible. These formed from a buildup of gas being released from damp ground and travelling through a tall magma pool. As the cool gas travels through the lava pool, the trails of these bubbles crystallize rock on the way out of the magma pool. These spires also record ‘bathtub rings’, small horizontal accumulations of crystallized lava on the side of spires that correspond to the heigh of the magma pool. The group split up to hike the many trails through the drained magma pool. Hiking down the blue Krokastigur trail, we saw large lava tubes (big enough to walk through), lava stalactites, and cooling joints.
Part 2 – Hverfjall tephra cone and surge deposits, Namafjall geothermal area (written by Victor Garcia)
The Hverfjall tephra cone is located at northern Iceland, east of Mývatn lake and south of Namafjall geothermal area. The tephra cone has around 400 m in elevation and a crater with about 1 km in diameter. The last eruption was ~2500 years ago and is associated with a series of surge and ash fall deposits of dark color that extend north and south of the crater.
The ash fall deposits are typically fine grained and unconsolidated while the surge deposits are finely stratified to massive. Surge deposits can be poorly-sorted, matrix supported lapilli-tuffs to well-sorted, clast supported lapilli-tuffs with individual layers presenting grain sorting. Typically, there is a centimeter scale intercalation between ash fall and surge deposits the extend laterally for several meters with localized cross-bedding stratification. The lava flows in the region are more recent and can partially cover the pyroclastic deposits. The volcanic cone and pyroclastic deposits are an example of phreatomagmatic eruptions dominated by groundwater with minor magma involved.
To the north of the tephra cone is the Namafjall geothermal area. It is a characteristic hydrothermally altered region forming a distinct light-red clay color due to the active hydrothermal activity. Geothermal power plants collect the hot water and use it to generate electricity, pumping back in the ground the cold water keeping a sustainable system. Additionally, the hydrothermal fluids carry significant amounts of sulfur that is mined.
Wednesday August 16th: Krafla
Part 1 – Hlid lava flows, Gaesafjoll rhyolite dome (written by Catherine Suclan)
The day started off with a short stop at the Hlid inflated lava flows along the North shore of Lake Mývatn. Inflation happens when an active lava flow develops a crust, and the molten lava is injected beneath the crust causing uplift. These flows demonstrated classic textures of inflated lava flows such as hornitos, lava rolls and tension cracks. Tension cracks were found in places of high topography. These happen when a lava with a crust reaches an obstacle, causing pressure to build and eventually cracking the surface. Lava rolls develop when lava oozes out of a crack and rolls along the surface. Hornitos are cone like or pipe like structures that are built up by the injection of splatter or lava through cracks.
After a long bumpy ride of chasing sheep of the road, we finally reached the Gæsafjöll rhyolite dome. The base of the dome consisted of dark coloured rhyolite glass that was jointed. Further up the dome towards the pinnacle, the rock composition changed. It was light grey, containing quartz, plagioclase, and pyroxene. Interestingly, garnet and other unknown minerals were found among the students. The actual composition is unknown. This rock was also columnar jointed which was oriented inwards into the dome, indicating a radial cooling surface within the dome. The jointing throughout the rhyolite dome indicates slow cooling. The change in rock composition and orientation of jointing indicates different phases of dome emplacement.
Part 2 – Viti crater, Krafla Fires lava flow complex (written by Thomas Mcloughlin-Coleman)
The third stop for the day was at Viti Crater, a marr or phreatomagmatic eruption. Walking up the trail from the parking lot to the crater we were confronted with just how large of a steam eruption it must have been to create this crater. Looking out from the walking path along the crater rim we could see pipes crossing the landscape carrying a mix of steam and hot water to the Krafla Power Plant just to the south.
The last stop of the trip was to the Krafla Fires lava flow complex. These rift related lava flows last erupted in the 1984, making them an excellent spot to observe flow textures and structures. The lavas in this area erupted as flows or as spatter cones from north-south trending fissures that developed along the Northern Volcanic Rift Zone. As we hiked around these flow we found that fissures has opened up in these latest flows and were venting steam from a heat source below. Fine fumarole minerals were found to be growing out of the steam on the surrounding basalts.
