Two large-scale north-dipping, low-angle normal faults cut the Everest massif at the top of the High Himalayan slab in Nepal. The upper fault the Qomolangma Detachment, follows the north slope of Everest from above the ‘Yellow Band’ at c. 8500 m on the Southwest Face down to the Rongbuk glacier. On the south side of Everest this fault places unmetamorphosed Ordovician mudstones and limestones a...

Sahagian et al. (2002a, 2002b) have developed a methodology for determining paleoelevations of highlands using observed vesicularities of lava flows. Since vesicular lavas preserve a record of paleoatmospheric pressure during the time of emplacement, they can be used to directly infer paleoelevations. Their model could act as a powerful tool, particularly in view of the uncertainties induced by...

Felsic magma commonly pools within shallow mushroom-shaped magmatic intrusions, so-called laccoliths or cryptodomes, which can cause both explosive eruptions and collapse of the volcanic edifice. Deformation during laccolith emplacement is primarily considered to occur in the host rock. However, shallowly emplaced laccoliths (cryptodomes) show extensive internal deformation. While deformation o...

Pumices, ashes, and tuffs from Mt. St. Helens and from Novarupta contain two principal forms of titanomagnetite: homogeneous grains with Curie temperatures in the range 350–500 C and oxyexsolved grains with similar bulk composition, containing ilmenite lamellae and having Curie temperatures above 500 C. Thermomagnetic analyses and isothermal annealing experiments in combination with stratigraph...

The mechanisms by which Cordilleran plutons are emplaced vary widely. However, the present authors have examined a series of plutons ranging from 2–35 km emplacement depth that have many common features, which suggest that downward transport of host rock is the most important mechanism during magma ascent and pluton emplacement. Many of these Cordilleran plutons preserve gently dipping, unfault...

At low temperatures (<750 °C at moderate to high crustal pressures), the production of suffi cient melt to reach the melt connectivity transition (~7 vol%), enabling melt drainage, requires an infl ux of aqueous fl uid along structurally controlled pathways or recycling of fl uid via migration of melt and exsolution during crystallization. At higher temperatures, melting occurs by fl uid-absent...

Magmatic stoping is discussed to be a main mechanism of magma emplacement. As a consequence of stoping, abundant country-rock fragments should occur within, and at the bottom of, magma reservoirs as "xenolith graveyards", or become assimilated. However, the common absence of sufficient amounts of both xenoliths and crustal contamination have led to intense controversy about the efficiency of st...

In analogy with hydrothermal processes on Earth’s seafloor, Martian hydrothermal systems may provide a mechanism for transporting water, chemicals, and energy to the surface. We model magmatic dike driven hydrothermal systems in which we consider changes to the surrounding permeability resulting from the emplacement of the dike (Craft, 2010) and calculate water fluxes to the surface. When compa...

Double-layered ejecta (DLE) craters are distinctive among the variety of crater morphologies observed on Mars, but the mechanism by which they form remains under debate. We assess two ejecta emplacement mechanisms: (1) atmospheric effects from ejecta curtain-induced vortices or a base surge and (2) ballistic emplacement followed by a landslide of ejecta assisted by either surfaceor pore-ice. We...