October 13, 2016
Sometimes you have to build the field in the laboratory. At the Virginia Tech Active Tectonics and Geomorphology Lab they do just that. This is the latest in a series of posts shared from their blog. More of their posts can be found here.
By Phil Prince
If this rock was metamorphosed 25 km deep, why am I holding it now? How did it get back up here? This is a reasonable question for students to ask, and requires them to consider the combined effects of rock uplift and erosional removal of overburden. This is a small and simple model, but it offers a direct explanation of the process of exhumation with movement of hypothetical rock particles indicated by colored dots. Burial, uplift and exhumation, and erosional transport to deposition and re-burial are illustrated. An interesting aspect of this simple model is its resemblance to early orogeny-scale interpretations of the European Alps, particularly Argand (1916). This basic structural style has repeatedly been described in subsequent works (Ford et al., 2006 for example), and can readily be illustrated for students by compressing weak strata between two rigid, and sloped, “buttresses.” The lack of decollements and underplating/duplexing within the model keeps it very simple, but the idea of erosional removal working with uplift to bring deep rock to the surface is clearly represented.
References and Further Reading:
Argand, E., 1916. Sur l’arc des Alpes Occidentales. Eclogae geologicae Helveticae (Lausanne), 14, p. 145-192.
Ford, M., Duchene, S., Gasquet, D., Vanderhaeghe, O., 2006. Two-phase orogenic convergence in the external and internal SW Alps, Journal of the Geological Society, London, 163, p. 815-826
This post was originally posted on 29 April 2016 at The Geo Models blog.