This essential reference for graduate students and researchers provides a unified treatment of earthquakes and faulting as two aspects of brittle tectonics at different timescales. The intimate connection between the two is manifested in their scaling laws and populations, which evolve from fracture growth and interactions between fractures. The connection between faults and the seismicity generated is governed by the rate and state dependent friction laws - producing distinctive seismic styles of faulting and a gamut of earthquake phenomena including aftershocks, afterslip, earthquake triggering, and slow slip events. The third edition of this classic treatise presents a wealth of new topics and new observations. These include slow earthquake phenomena; friction of phyllosilicates, and at high sliding velocities; fault structures; relative roles of strong and seismogenic versus weak and creeping faults; dynamic triggering of earthquakes; oceanic earthquakes; megathrust earthquakes in subduction zones; deep earthquakes; and new observations of earthquake precursory phenomena.

The Mechanics of Earthquakes and Faulting

Orogenic gold deposits : A proposed classification in the context of their crustal distribution and relationship to other gold deposit types

Orogenic gold and geologic time: a global synthesis

Structural permeability of fluid-driven fault-fracture meshes

Fluid inclusions in hydrothermal ore deposits

Many mesothermal gold-quartz deposits are localized along high-angle reverse or reverse-oblique shear zones within greenstone belt terrains. Characteristically, these fault-hosted vein deposits exhibit a mixed "brittle-ductile" style of deformation (discrete shears and vein fractures as well as a schistose shear-zone fabric) developed under greenschist facies metamorphic conditions. Many of the vein systems are of considerable vertical extent (>2 km); they include steeply dipping fault veins (lenticular veins subparallel to the shear-zone schistosity) and, in some cases, associated flats (subhorizontal extensional veins). Textures of both vein sets record histories of incremental deposition. We infer that the vein sets developed near the roofs of active metamorphic/magmatic systems and represent the roots of brittle, high-angle reverse fault systems extending upward through the seismogenic regime. Friction theory and field relations suggest that the high-angle reverse faults acted as valves , promoting cyclic fluctuations in fluid pressure from supralithostatic to hydrostatic values. Because of their unfavorable orientation in the prevailing stress field, reactivation of the faults could only occur when fluid pressure exceeded the lithostatic load. Seismogenic fault failure then created fracture permeability within the rupture zone, allowing sudden draining of the geopressured reservoir at depth. Incremental opening of flats is attributed to the prefailure stage of supralithostatic fluid pressures; deposition within fault veins is attributed to the immediate postfailure discharge phase. Hydrothermal self-sealing leads to reaccumulation of fluid pressure and a repetition of the cycle. Mutual crosscutting relations between the two vein sets are a natural consequence of the cyclicity of the process. Abrupt fluid-pressure fluctuations from this fault-valve behavior of reverse faults seem likely to be integral to the mineralizing process at this structural level.

High-angle reverse faults, fluid-pressure cycling, and mesothermal gold-quartz deposits

Gold-quartz vein fields in metamorphic terranes such as greenstone belts provide evidence for the involvement of large volumes of fluids during faulting and may be products of seismic processes near the base of the seismogenic regime. In the Val d'Or district of the Abitibi greenstone belt, Canada, quartz-tourmaline-carbonate veins form a vein field (30 × 15 km) in the hanging wall of a crustal-scale fault zone, which was the main channelway for upward migration of the deeply generated fluids. The veins occur in small high-angle reverse faults and in adjacent horizontal extensional fractures extending up to 75 m in intact rocks. They have formed incrementally during active reverse faulting in response to crustal shortening, at depths corresponding to those at the base of the seismogenic zone in actively deforming crust. Detailed structural and fluid inclusion studies provide evidence for generally lithostatic but fluctuating fluid pressures (ΔPƒ of the order of 200 MPa) and for cyclic stress reversals during vein formation and provide good support for the fault valve model. A comparison of vein characteristics with “standard” earthquake rupture parameters suggests that each slip increment along veins in reverse faults was accompanied by a small earthquake (4 > M > 3 or less). The large vein field thus represents both the extent of fluid dispersion in the hanging wall of a crustal-scale channelway and the distribution of small earthquakes integrated over the lifetime of the hydrothermal system. It is proposed that such small earthquakes along veins in reverse faults are related to large earthquakes (M > 6) nucleating near the base of the seismogenic regime along the nearby crustal-scale fault, either as aftershocks or as a precursory smarm.

Gold‐quartz veins in metamorphic terranes and their bearing on the role of fluids in faulting

Palaeoseismic events recorded in Archaean gold-quartz vein networks, Val d'Or, Abitibi, Quebec, Canada

Fluid inclusions have been studied in a quartz-epidote-actinolite vein within a Proterozoic diabase dike crosscutting the Donalda 1 gold-bearing quartz vein, near Noranda, Quebec. Two types of fluid inclusions were recognized. The first type is represented by two-phase aqueous fluid inclusions characterized by low eutectic ( 200DGC) temperatures. The second type is represented by two- or three-phase (+ or - solid) aqueous fluid inclusions characterized by low eutectic ( 2 O-CO 2 and CO 2 fluid inclusions in Archean gold-bearing quartz veins of the southeastern Abitibi belt and has a chemical composition (Ca-Na-Cl-bearing with variable salinity) comparable to that of brines and ground waters found in the Superior province. This study demonstrates that these low T h aqueous fluids showing variable salinity are unrelated to gold deposition, but should rather be correlated with younger brines and ground waters which percolated downward in the continental crust. In these gold-bearing quartz veins, only the high T h aqueous fluids may be linked to gold-bearing fluids.

François Robert

Papers

High-angle reverse faults, fluid-pressure cycling, and mesothermal gold-quartz deposits

Gold‐quartz veins in metamorphic terranes and their bearing on the role of fluids in faulting

Palaeoseismic events recorded in Archaean gold-quartz vein networks, Val d'Or, Abitibi, Quebec, Canada

On the significance of aqueous fluid inclusions in gold-bearing quartz vein deposits from the southeastern Abitibi Subprovince (Quebec, Canada)

Dating old gold deposits