The Weird Tectonics of Play Sand and Silly Putty
Bruno C. Vendeville, Ph.D.
The first example deals with the onset of wrenching (i.e., strike-slip) movement within a tectonic plate. It is commonly assumed that intraplate wrenching occurs because of the presence of preexisting structural fabric or planes of weakness that are reactivated by strike-slip. Using physical models, I will show that a preexisting fabric is not required for strike-slip to occur. In a tectonic plate undergoing compression, the presence of weak areas, such as former extensional basins, is enough to trigger wrenching, depending on the basins' location. Experiments also show that the structural style of the wrench zone varies greatly (from a Dead Sea-style to a classic Riedel type), depending on slight changes in the imposed boundary conditions.
The second example deals with the origin of curved fold belts, such as the Jura and the Sierra Madre Oriental. Arcuate fold belts are traditionally attributed to the presence of an indenter in the hinterland, and/or of the curvature of the detachment pinch-out in the foreland. Experiments suggest that an unexpected other parameter is sufficient to promote the growth of arcuate folds, the curvature of the detachment on the hinterland side. This curvature in itself is enough to produce highly arcuate fold trains.
Bruno C. Vendeville received his Masterís degree from the University of Paris XI in 1984 and his Ph.D. from the University of Rennes, France, in 1987. He was a postdoctoral Fellow at the Center for Tectonophysics (Texas A&M University) from 1987 to 1988 before joining the Bureau of Economic Geology in 1989, where he is now a Senior Research Scientist.
Bruno specializes in salt tectonics, faulting analysis, and experimental modeling of tectonic processes, including salt tectonics, extensional tectonics, fold-and-thrust belts, magmatic intrusions, and gravity instabilities. He manages the experimental tectonics laboratory at the BEG.