Study Tour

2013 Geodynamics Program
EXPERIMENTS: Simulating The Earth In THe Lab

The theme of this year's Geodynamics Seminar Series is "Experiments".  For the field trip we will be traveling to Clermont-Ferrand, France to visit the experimental facilities at the Laboratoire Magmas et Volcans which is one of the top high temperature/pressure experimental laboratories in Europe. It also boasts an exceptional location: situated at the foot of the soon-to-be UNESCO World Heritage site “Chaîne des Puys”, comprised of a series on monogenetic volcanoes, formed between 70,000 and 6,000 years ago, as well as the Limagne Fault, which forms the western edge of the Limagne Graben. Led by geologists from the Laboratoire Magmas et Volcans, we will wander the wonders of the Massif Central. In particular, students will learn about the Chaîne des Puys, which hold a prominent place in the history of volcanology because its volcanic features played an important role in settling the late 18th century controversy regarding the origin of basalt (i.e. Abraham Werner and the Neptunists vs James Hutton and the Plutonists). The volcanoes form a N-S-trending chain of basaltic and trachytic cinder cones, basaltic maars, and trachytic lava domes that has been active into the Holocene. Construction of the present-day Chaîne des Puys began about 70,000 years before present (BP), and was largely completed by the beginning of the Holocene. Holocene eruptions constructed lava domes such as the Puy de Dôme, whose growth was accompanied by pyroclastic flows, cinder cones that fed lengthy lava flows, and maars. The latest well-documented activity took place about 6000 years BP near Besse-en-Chandesse and included the powerful explosions that formed the Lac Pavin maar. Students will also learn about the tectonics of the intracontinental rifting that formed the Limagne Graben, which is downthrown from the Massif Central by a series of normal faults. The graben contains about 2 km of sediments, and the amount of crustal stretching is estimated at 1.2–1.3. Rifting began in the Late Eocene and continued into the Late Oligocene. It is part of the European Cenozoic Rift system, which includes the Rhine Graben, which formed in response to compressional deformation of the Alpine foreland.

On the return trip from France on July 1, we will briefly visit Iceland to take a small trip out onto the Reykjanes Peninsula to see where the Mid-Atlantic Ridge rises out of the Atlantic Ocean, and where we can walk across the Leif the Lucky (or Miðlína) Bridge, which spans the Álfagjá rift valley (60 feet wide and 20 feet (6.1m) deep), and marks the boundary of the Eurasian and North American tectonic plates.