Professor of Marine Geology and Geophysics
Oceanic core complexes with large elongate domal edifices (megmamullions), pronounced corrugated surfaces and low-angle detachment faults are a relatively common feature of the inside corners of transform fault/ridge intersections, especially along slow spreading mid-ocean ridge systems. There is much current debate, however, concerning the origin of these features. This essay will review the critical marine geological and geophysical observations, the models and the implications of oceanic core complexes for the evolution of crust and mantle, lithosphere rheology and the structural styles that develop in extensional and compressional settings.
Selected References:
Buck, W. R., L. L. Lavier, and A. N. B. Poliakov (2005), Modes of faulting at mid-ocean ridges, Nature, 434, 719-723.
Canales, J. P., B. E. Tucholke, M. Xu, J. A. Collins, and D. L. DuBois (2008), Seismic evidence for large-scale compositional heterogeneity of oceanic core complexes, Geochemistry Geophysics Geosystems, 9, doi:10.1029/2008GC002009.
MacLeod, C. J., R.C. Searle, B.J. Murton, J.F. Casey, C. Mallows, S.C. Unsworth, K.L. Achenbach and M. Harris (2009), Life cycle of oceanic core complexes, Earth and Planetary Science Letters, 287, 333-344 doi:10.1016/j.epsl.2009.08.016
Schroeder, T., and B. E. John (2004), Strain localization on an oceanic detachment fault system, Atlantic Massif, 30oN, Mid-Atlantic Ridge, Geochemistry Geophysics Geosystems, 5, doi:10.1029/2004GC000728.
Searle, R. C., M. Cannat, K. Fujioka, C. Mevel, H. Fujimoto, A. Bralee, and L. Parson (2003), FUJI Dome : a large detachment fault near 64oE on the very slow spreading southwest Indian Ridge, Geochemistry Geophysics Geosystems, 4, 9105.
Tucholke, B. E., J. Lin, and M. C. Kleinrock (1998), Megamullions and mullion structure defining oceanic metamorphic core complexes on the Mid-Atlantic Ridge, J. Geophys. Res., 103, 9857-9866.