Please use this identifier to cite or link to this item:
Title: Interaction between Crustal-Scale Darcy and Hydrofracture Fluid Transport: A Numerical Study
Author: de Riese, T.
Bons, Paul D.
Gómez Rivas, Enrique
Sachau, Till
Keywords: Geologia estructural
Structural geology
Issue Date: 5-Nov-2020
Publisher: Wiley Hindawi Publishing
Abstract: Crustal-scale fluid flow can be regarded as a bimodal transport mechanism. At low hydraulic head gradients, fluid flow through rock porosity is slow and can be described as diffusional. Structures such as hydraulic breccias and hydrothermal veins both form when fluid velocities and pressures are high, which can be achieved by localized fluid transport in space and time, via hydrofractures. Hydrofracture propagation and simultaneous fluid flow can be regarded as a 'ballistic' transport mechanism, which is activated when transport by diffusion alone is insufficient to release the local fluid overpressure. The activation of a ballistic system locally reduces the driving force, through allowing the escape of fluid. We use a numerical model to investigate the properties of the two transport modes in general and the transition between them in particular. We developed a numerical model in order to study patterns that result from bimodal transport. When hydrofractures are activated due to low permeability relative to fluid flux, many hydrofractures form that do not extend through the whole system. These abundant hydrofractures follow a power-law size distribution. A Hurst factor of ~0.9 indicates that the system self-organizes. The abundant small-scale hydrofractures organize the formation of large-scale hydrofractures that ascend through the whole system and drain fluids in large bursts. As the relative contribution of porous flow increases, escaping fluid bursts become less frequent, but more regular in time and larger in volume. We propose that metamorphic rocks with abundant veins, such as in the Kodiak accretionary prism (Alaska) and Otago schists (New Zealand), represent regions with abundant hydrofractures near the fluid source, while hydrothermal breccias are formed by the large fluid bursts that can ascend the crust to shallower levels.
Note: Reproducció del document publicat a:
It is part of: Geofluids, 2020, vol. 2020, num. 8891801
Related resource:
ISSN: 1468-8115
Appears in Collections:Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

Files in This Item:
File Description SizeFormat 
708932.pdf1.74 MBAdobe PDFView/Open

This item is licensed under a Creative Commons License Creative Commons