ERIC C. FERRE
Office: 301B Parkinson Lab
My main research interest is the deformation of the lithosphere. I use and develop new magnetic approaches to quantify anisotropy, mineral fabrics and finite strain in rocks. Current projects cover a broad spectrum from seismic deformation and collateral magnetic effects in pseudotachylytes to ductile flow and kinematics in the lower continental crust and upper mantle. Most of these projects address problems of mechanical coupling between different lithospheric layers (clutch tectonics). My students and myself enjoy both research in the field and in the laboratory. Our field areas are located in California, the Italian Alps, SW Japan, New Caledonia, Minnesota, Montana and South Africa.
Dynamics of mafic layered magmatic intrusions
Mafic layered intrusions are thought to represent fossil mafic magma chambers. Such intrusions occur in different geologic settings at different times in the Earth history. In the Archean-Proterozoic, they formed very large anorogenic tabular bodies such as the Bushveld, Great Dike, Duluth complexes. In the Phanerozoic, they tend to form smaller extension-related intrusions such as the Skaergaard or the Rum complexes. These intrusions display compositional layering at a scale from a few centimeters up to several hundreds of meters. The origin of this layering is still problematic. Convective flow, cumulative processes and static recrystallization processes should produce different types of fabrics in such systems. We use magnetic techniques to evaluate the role of several layering-forming processes.
Flow and rheology of the partially molten continental crust
Continental collision results in substantial lithospheric and crustal thickening which, in turns, leads to partial melting at lower and mid crustal levels. The presence of a partially molten layer under collision zones such as the Tibet Plateau has been documented by both seismic data and magneto-telluric experiments. One of the key issues to understand the evolution of orogenic belts is to find out if the molten material flows parallel to the convergence direction (i.e. parallel to plate motion) or if it flows laterally (i.e. parallel to the orogen). These models are currently highly debated and prompted us to develop new petrophysical methods to investigate flow and kinematics of the partially molten lower crust. Thus far, we have concentrated on migmatites because they are representative of the anatectic continental crust. The anisotropy of magnetic susceptibility (AMS) proved to be a unique tool to obtain reliable information on flow fabrics in migmatites. The methodological developments were carried out on migmatites exposed in the Morton quarries in Minnesota. Although we continue to refine and develop the magnetic techniques we also combine them with original structural analysis investigations (e.g. image analysis). A tomographic study of leucosome distribution, conducted on large cut slabs of rocks, suggests that the leucosomes form a network of cigar shaped pockets of melt.
In most migmatites, kinematic analysis is limited by the lack of a well developed mineral lineation. The low-field AMS provides a rapid measurement of the flow direction. The obliquity between the low-field and high-field AMS allows in most cases to determine the sense of shear during non coaxial flow. Magnetic fabrics offer a quick way of quantifying anisotropy and strain. Two new and very well exposed field areas have been selected, the Okanagan dome (Washington) and the Naxos dome (Greece), to test the new methodology on regional scale problems.
Origin of high magnetic remanence in fault pseudotachylytes
Frictional heating during coseismic deformation may lead to melting of the fault rocks and formation of pseudotachylite if slip is important. The increasingly reported existence of earthquake lightning shows that transient coseismic electric currents of large intensity are associated with large magnitude earthquakes (M > 6.0). Such currents are likely to follow pseudotachylite veins because their electric conductivity, being melts, is considerably larger than that of the unmolten rocks. All previous and preliminary results on fault-related pseudotachylites show that they have an anomalously high remanent magnetization. Their remanent magnetic properties are similar to those of lightning struck rocks, which suggests that large electric pulses were involved in the magnetization. This project aims at demonstrating that remanence anomalies in pseudotachylites are generally observed and that coseismic electric currents are responsible for it. We propose to test the hypothesis on three young pseudotachylites from seismically active zones (California, Japan and Western Alps) by collecting oriented samples for paleomagnetic studies. Samples collected at various points with respect to the main fault plane enable us to test the coseismic current hypothesis. The geometry and the characteristics of the magnetizing field are compared with the Earth's magnetic field at the time of pseudotachylite formation. This provides an independent second test for the coseismic current hypothesis. A series of experiments will generate artificial pseudotachylites using the friction welding method. The artificial and natural pseudotachylites will be compared to assess the possible causes of anomalous magnetization in natural specimens. The direct study of coseismic currents is made difficult by their transient nature. This problem can be solved by using the remanent magnetic record of rocks affected by the electrical phenomenon. This research will open new directions of investigation on coseismic electric currents in fault rocks and should contribute to a better understanding of coseismic electric phenomena.
Selected Recent Publications:
Ferré, E.C., Chou, Y.-M., Kuo, R.-L., Yeh, E.-C., Leibovitz, N.R., Meado, A. L., Campbell, L., and Geissman, J.W. (2016). Deciphering viscous flow of frictional melts with the mini-AMS method. Journal of Structural Geology, 90, 15-26, doi:10.1016/j.jsg.2016.07.002.
Ferré, E.C., Yeh, E.-C., Chou, Y.-M., Kuo, R.-L., Chu, H.-T., and Korren, C.S. (2016) Brushlines in fault pseudotachylytes: a new criterion for coseismic slip direction. Geology, doi:10.1130/G37751.1.
Korren, C.S., Ferré E.C., Yeh, E.-C., Chou Y.-M., and Chu, H.-T. (2016). Seismic rupture parameters deduced from a Pliocene fault pseudotachylyte in Taiwan. AGU Monograph “Evolution of Fault Zone Properties and Dynamic Processes during Seismic Rupture”, edited by Marion Y. Thomas, Harsha S. Bhat, Thomas M. Mitchell, in press.
Trela, J., Ferré, E.C., Launeau, P., Bartz, D.M., and Morris, A. (2015). Magmatic accretion and thermal convection at the sheeted dikes-gabbros boundary in superfast spreading crust, ODP Hole 1256D. Tectonophysics, doi: 10.1016/j.tecto.2015.08.023.
Ferré, E.C., Geissman, J.W., Chauvet, A., Vauchez, A. and Zechmeister, M.S. (2015). Focal mechanism of prehistoric earthquakes deduced from pseudotachylyte fabric. Geology, doi:10.1130/G36587.1.
Ferré, E.C., Geissman, J.W., Gattacceca, J., Demory, F., Zechmeister, M.S. and Hill, M.J. (2014). Coseismic magnetization of fault pseudotachylytes: 1. Thermal demagnetization experiments. Journal of Geophysical Research: Solid Earth, 119, doi:10.1002/2014JB011168.
Ferré, E.C., Gébelin, A., Till, J.L., Sassier, C., and Burmeister, K.C. (2014). Deformation and magnetic fabrics in ductile shear zones: A review. Tectonophysics, doi: 10.1016/j.tecto.2014.04.008.
Friedman, S.A., Feinberg. J.M., Ferré, E.C., Demory, F., Martín-Hernández, F., Conder, J.A., and Rochette, P. (2014). Cratons vs. rift uppermost mantle contributions to magnetic anomalies in the United States interior. Tectonophysics, doi: 10.1016/j.tecto.2014.04.023.
Ferré, E.C., Gébelin, A., Conder, J.A., Christensen, N, Wood, J.D., and Teyssier, C. (2014). Seismic anisotropy of the Archean crust in the Minnesota River Valley, Superior Province. Geophysical Research Letters, 41, 5, 1514-1522. doi:10.1029/2013GL059116.
Ferré, E.C., Friedman, S.A., Martín-Hernández, F., Feinberg, J.M., Till, J.L., Ionov, D.A., and Conder, J.A. (2014). Eight good reasons why the uppermost mantle could be magnetic. Tectonophysics, http://dx.doi.org/10.1016 /j.tecto.2014.01.004.
Ferré, E.C., Friedman, S.A., Martín-Hernández, F., Feinberg, J.M., Conder, J.A. and Ionov, D.A. (2013). The magnetism of mantle xenoliths and potential implications for sub-Moho magnetic sources. Geophysical Research Letters, 40, doi:10.1029/2012GL054100.
Ferré, E.C., Michelsen, K.J., Ernst, W.G., Boyd, J.D. and Canon-Tapia, E. J. (2012). Vertical zonation of the Mount Barcroft granodiorite, White Mountains, California: implications for magma chamber processes. American Mineralogist, 97, 1049-1059.
Ferré, E.C., Geissman, J.W. and Zechmeister, M.S. (2012), Magnetic properties of fault pseudotachylytes in granites. Journal of Geophysical Research: Solid Earth, 117, B01106, doi:10.1029/2011JB008762.
Ferré, E.C., Galand, O., Montanari, D. and Kalakay, T.J. (2012). Granite magma migration and emplacement along thrusts. International Journal of Earth Science, doi:10.1007/s00531-012-0747-6.
GEOL 302 Fundamentals of Structural Geology I
GEOL 454 Field Geology
GEOL 466 Tectonics
GEOL 535 Advanced Topics: Rock Magnetism and Paleomagnetism