The results of numerical modelling show that the mechanical stratification of the crust provides the fundamental control on fault spacing and, ultimately, the mode of extension. Macroscopic pre-existing structures and weaknesses are often thought to govern the behaviour of continental crust under extension, and many prior studies have focussed on the effect of heterogeneities in triggering faul...

a r t i c l e i n f o Crust extracted from the mantle in arcs is refined into continental crust in subduction zones. During sediment subduction, subduction erosion, arc subduction, and continent subduction, mafic rocks become eclogite and may sink into the mantle, whereas more silica-rich rocks are transformed into felsic gneisses that are less dense than peridotite but more dense than the uppe...

[1] One process for the formation of continental crust is the accretion of arc terranes at continental margins. A longstanding problem with this model is that although the composition of the continental crust is andesitic, the majority of arc lavas are basaltic. Moreover, those arc lavas that are andesitic tend to be evolved (lower Mg #) compared to the continental crust. Continental crust can ...

There must be a transition from continuous porous flow to transient formation of melt-filled fractures in the region of magma transport below oceanic spreading centers. This transition may occur at permeability barriers that impede porous flow of melt, at the base of the oceanic crust and within the lower crust. We summarize evidence for formation of melt-filled lenses at the base of the crust ...

Seismic structure beneath the contiguous U.S. was imaged with multimode receiver function stacking and inversion of Rayleigh wave dispersion and ellipticity measurements. Crust thickness and elevation are weakly correlated across the contiguous U.S., but the correlation is ~3–4 times greater for separate areas east and west of the Rocky Mountain Front (RMF). Greater lower crustal shear velociti...

We estimate the three-dimensional (3D) P-wave attenuation structure beneath the Niigata–Kobe Tectonic Zone (NKTZ), central Japan, using high-quality waveform data from a large number of stations. The obtained results confirm the segmentation of the NKTZ into three regions, as suggested by 3D seismic velocity models, and reveal characteristic structures related to surface deformation, shallow su...

Intermediate-period Rayleigh and Love waves propagating across Tibet require marked radial anisotropy within the mid-lower crust, consistent with a thinning of it. The anisotropy is largest in the western part of the plateau where the moment tensors of earthquakes indicate active crustal thinning. A preferred orientation of mica crystals resulting from the crustal thinning can account for the o...