Mineral physics observations suggest that distinct density and rheological differences exist between the crustal component of oceanic lithosphere and the underlying mantle. We have conducted numerical experiments to investigate the influence of both density and viscosity on the effectiveness of recycling of oceanic crust into the lower mantle. Confirming previous results, the density inversion ...

Structural and tectonic patterns mapped in Fortuna Tessera are interpreted to reflect a change in the style and intensity of deformation from east to west, beginning with simple tessera terrain at relatively low topographic elevations in the east and progressing through increasingly complex deformation patterns and higher topography to Maxwell Montes in the west. These morphologic and topograph...

The exact solutions for the isotopic compositions and the concentrations of the two-reservoir model for mantle-crust evolution are given for arbitrary rates of crustal growth and of back flow to the mantle. The critical parameters are the chemical fractionation factors for crustal growth and refluxing and the integrated fractional mass-removal rates from the crust and the mantle. For the case w...

Prior to large earthquakes (e.g. 1995 Kobe earthquake, Japan), an increase in the atmospheric radon concentration is observed, and this increase in the rate follows a power-law of the time-to-earthquake (time-to-failure). This phenomenon corresponds to the increase in the radon migration in crust and the exhalation into atmosphere. An irreversible thermodynamic model including time-scale invari...

[1] Mercury exhibits long-wavelength topography which has probably survived for 4 Ga. Assuming Airy compensation, the survival of the topography indicates that only certain combinations of crustal thickness and thermal structure are allowable. A dry diabase rheology allows a thicker crust than a dry plagioclase rheology. The existence of ancient faults places some constraints on the thermal str...

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...

Simultaneous Mars Atmosphere and Volatile EvolutioN mission (MAVEN) plasma and magnetic field observations reveal a detached magnetic flux rope in the Martian induced magnetosphere. The flux rope was identified by an increase in the magnetic field amplitude accompanied by smooth vector rotations. In addition, MAVEN observed a pronounced ion composition change across the structure, with solar wi...

The Precambrian geological record shows peak of activity at 1.1, 1.9–2.1, 2.7 and 3.5 Ga, often associated with massive crustal production, orogenesis and supercontinent cycles. It has been suggested that these bursts of tectonic activity are due to mantle avalanche events, where accumulating subducted slabs periodically penetrate the 670 km discontinuity, and subsequent upwelling counterflow a...

We describe a model of crustal deformation and thermal structure across the Nepal Himalaya over the last 20Myr. The model assumes that, throughout this period, shortening across the range has been entirely taken up by slip along a single thrust fault, the Main Himalayan Thrust (MHT) Fault, and that the growth of the Himalayan wedge has resulted from the development of a duplex at mid-crustal sc...

We evaluate the parameters that control the thickness of ductile shear zones that are generated by viscous heating. We employ two-dimensional thermomechanical numerical models to simulate shear zone development under compression. Results show that the shear zone thickness is essentially independent on the numerical resolution and the initial size of a weak inclusion that triggers shear localiza...