Seismic pumping—a hydrothermal fluid transport mechanism

Abstract

A consequence of the dilatancy/fluid-diffusion mechanism for shallow earthquakes is that considerable volumes of fluid are rapidly redistributed in the crust following seismic faulting. This is borne out by the outpourings of warm groundwater which have been observed along fault traces following some moderate (M5–M7) earthquakes. The quantities of fluid involved are such that significant hydrothermal mineralisation may result from each seismically induced fluid pulse, and the mechanism provides an explanation for the textures of hydrothermal vein deposits associated with ancient faults, which almost invariably indicate that mineralisation was episodic.

Genesis of Syntectonic Hydrothermal Veins in the Igneous Rock of Teschenite Association (Outer Western Carpathians, Czech Republic): Growth Mechanism and Origin of Fluids

“…The fluid movement was mainly driven by the tectonic suction pump which continuously supplied ions into the fluid. The vein-forming components were transported mainly by diffusion to their deposition site (Sibson et al 1975). Similarly, fibrous crystals growing in small cracks (due to prevention of the growth of competition) do not favour large-scale fluid conduits.…”

The role of the fluid phase during regional metamorphism and deformation

“…5, ductile deformation at high strain rate and at high P, is likely to induce microcracking and therefore enhance permeability. The resultant dilatancy also gives rise to gradients in PI, drawing fluids into the deforming zone, somewhat analogous to the dilatancy or seismic pumping mechanisms at higher crustal levels (Scholz, Sykes & Aggarwal, 1973;Sibson, Moore & Rankin, 1975). However, there is substantial evidence for Pf > P, within ductile shear zones (Beach, 1976;Kerrich & Allison, 1978), and we believe that permeability enhancement by ductile deformation is the more important cause for fluid channelling in such zones.…”

Depósitos de Pb-Zn-Cu-Ba-F-Sr epigenéticos estratoligados en series sedimentarias en relación con salmueras de cuenca: depósitos de tipo “Mississippi Valley” (MVT) y similares en México

“…Existe un conjunto de modelos de movilización de fl uidos propuestos hasta la fecha, entre los que cabe destacar fl ujo por compactación de sedimentos (Jackson y Beales, 1967); fl ujo por bombeo sísmico (Sibson et al, 1975); fl ujo debido a procesos diagenéticos (Sharp, 1978); fl ujo debido a gradientes topográfi cos ("gravity-driven fl ow"; Garven y Freeze, 1984a, 1984b; y fl ujo debido a movimientos tectónicos ("tectonically-driven fl ow"; Oliver, 1986).…”

“…El fl ujo por bombeo sísmico (Sibson et al, 1975) es un mecanismo que puede generar grandes velocidades de fl ujo de hasta decenas de metro por año y que, a pesar de que el volumen de fl uido movilizado a escala de cuenca puede no ser muy elevado, si que localmente puede ser un factor importante para la formación de depósitos minerales. Este tipo de mecanismo fue invocado por Tritlla y Cardellach (1997) en relación con los depósitos de Hg encajonados en carbonatos de la Sierra de Espadan (Castellón, España).…”