Transport phenomena in hydrothermal systems; the nature of porosity

Norton, D.; Knapp, Richard B.

doi:10.2475/ajs.277.8.913

Cited by 283 publications

(146 citation statements)

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“…Appropriate horizontal permeabilities of F and C are from 10 −12 to 10 −11 m 2 that are higher than the general permeabilities of fractured rocks (e.g. Norton and Knapp, 1977). This result indicates that a sufficient water supply by a lateral flow is needed for the magma-hydrothermal system of Usu volcano.…”

Section: Time-dependent Permeability-models 3 and 4-mentioning

confidence: 70%

Mathematical simulation of magma-hydrothermal activity associated with the 1977 eruption of Usu volcano

Matsushima

2014

Earth Planet Sp

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During the 1977 eruption of Usu volcano, magma was emplaced at shallow crust. This intrusion induced fumarole activity immediately after the eruption. Based on the repeated thermal observations, the amount of heat discharged by this thermal activity is estimated to be 2 × 10 17 J. The corresponding volume of the intrusion is 6 × 10 7 m 3 . The inferred intrusion volume is comparable to the volume of the resistive block beneath the major faults formed by this eruption, which was interpreted as a cooled intrusion on the basis of recently conducted MT surveys. The heat discharge rate is a surface boundary condition for an underlying magma hydrothermal system. A mathematical simulation, which accounts for multiphase mass and heat transport within a porous media, is conducted to reproduce the thermal activity of Usu volcano. The simulation incorporates the supply of latent heat by solidifying magma and heat transfer by degassing. Permeability conditions are important factors to fit the simulated heat discharge rate with the observation. Increased permeability of surrounding formations causes early appearance and high amplitude of surface heat discharge rate and reduced permeability causes opposite effect. The intrusion permeability has a strong influence on the surface thermal activity. High permeability is needed for the early appearance of the surface heat discharge rate, although it results in the maximum intrusion temperature that is much lower than the observed fumarolic temperature. To avoid the inconsistency, temperature dependent permeability is used in the simulation. The inside of the intrusion with the temperature dependent permeability that has low initial values and the high permeable margin are supposed to satisfy the conditions of the observed surface heat discharge rate and fumarolic temperature.

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Section: Time-dependent Permeability-models 3 and 4-mentioning

confidence: 70%

Mathematical simulation of magma-hydrothermal activity associated with the 1977 eruption of Usu volcano

Matsushima

2014

Earth Planet Sp

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“…Such estimates can provide constraints on permeability of uncemented crust, such as might be present in very young crust at spreading axes. Norton and Knapp (1977) gave a model that assumes infinite planar fractures in an ideal system and does not take into account fracture continuity, tortuosity, or wall roughness. In this model, permeability (K) is a function only of fracture spacing (n) and aperture (d), where K = ncP/12.…”

Section: Permeability and Permeability Evolutionmentioning

confidence: 99%

Ridge-Flank Alteration of Upper Ocean Crust in the Eastern Pacific: Synthesis of Results for Volcanic Rocks of Holes 504B and 896A

Alt¹,

Teagle²,

Laverne³

et al. 1996

Proceedings of the Ocean Drilling Program, 148 Scientific Results

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The lithostratigraphy and alteration of volcanic basement from Holes 504B and 896A, located in different parts of a ridge flank circulation cell, are summarized and compared. The 290-m-thick volcanic section of Hole 896A is located on a basement high that coincides with high heat flow and upwelling fluids. The 571.5-m-volcanic section of Hole 504B is located ~l km away in an area of ambient heat flow. Subtle differences in lithostratigraphy include slightly greater proportions of massive units and fewer pillow basalts in Hole 896A than in Hole 504B. The volcanic sections are geochemically similar, but there is no direct correlation of lithologic or geochemical units between the two sites. Veins are comparable in abundance in the two sections (-30 veins/m, mean vein width < 1 mm), but carbonate veins and thick (>2 mm) saponite and carbonate veins are more abundant in Hole 896A than in Hole 504B. Permeabilty values of the upper basement sections in Holes 896A and 504B are similar (~IO~1 3 to 10~1 4 m 2 ), suggesting that the upper -200 m of basement is sufficiently permeable on a regional scale to support circulation of seawater through basement.Alteration effects in basement from Hole 896A are similar to those in the upper 320 m of volcanic rocks in Hole 504B. These include celadonitic phyllosilicates in fractures and alteration halos and reddish, Fe-oxyhydroxide-rich alteration halos along fractures. Dark gray rocks, characterized by the presence of saponite ± carbonate ± pyrite occur throughout Hole 896A and the entire Hole 504B volcanic section. Alteration reflects evolution from open circulation of cold, oxidizing seawater, to more restricted circulation of seawater caused by burial of the crust by sediments and sealing of fractures with saponite. Latestage carbonates and minor zeolites formed in veins throughout both holes from reacted seawater fluids (decreased fluid Mg/ Ca). Oxygen and strontium isotopic evidence indicate an early generation of carbonates in both holes that formed at relatively low temperatures (~25°-35°C) during open circulation, whereas later carbonates in Hole 896A formed at slightly higher temperatures (~50°-70°C) during more restricted circulation, possibly similar to the present ridge flank hydrothermal upflow conditions (~50°-80°C).Chemical changes in altered upper crust include oxidation, increased alkalis, Mg, CO 2 , and H 2 O; local uptake of P; elevated δ l8 θ, δD, δ"B, and 87 Sr/ 86 Sr; and lower S contents and δ 34 S. The greatest chemical changes occur in alteration halos and breccias, and the smallest chemical changes occur in the lower volcanic section of Hole 504B. Secondary minerals filling fractures and cementing breccias are sites of uptake of Mg, CO 2 , and H 2 O, in addition to changes occurring in altered rocks.

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“…The terms effective porosity (ηE as the dominant mode of fluid transport through flow), diffusion porosity (ηD as the dominant mode of aqueous diffusion) and residual porosity (ηR where not flow takes place due to lack of inter-pore connection) are described by Norton and Knapp (1977), whereas Tullborg and Larson (2006) employ connected porosity (ηC which are pores available for water saturation) and unconnected porosity (ηN = total porosity minus connected porosity). These parameters are placed in context in Eq.…”

Section: Connectivity Of Porositymentioning

confidence: 99%

Porosity Reviewed: Quantitative Multi-Disciplinary Understanding, Recent Advances and Applications in Vadose Zone Hydrology

Dippenaar¹

2013

Geotech Geol Eng

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Porosity -one of the most basic mechanical properties of a mediumhas implications in a vast range of disciplines and used for a similar vast range of applications. These include, for instance, the storage and flow of water; the compressible component of earth materials, which can be subjected to consolidation under loading; the variable parameter in the swelling and shrinkage of clays; and possibly a governing parameter in the formation of wetlands and perched water tables. This review notes the relevance of a fourfold quantification of porosity for vadose zone studies, viz. (1) type (matrix or structure), (2) scale (submicro to macro scale), (3) connectivity, and (4) water saturation. This is followed by a review of recent advances in the quantification and description of porosity in porous media (visual and remote sensing methods, porosimetry, geometrical approaches, empirical estimations, densest packing simulations, etc.), the applications to quantification of hydrological parameters, and a brief glimpse into the significance of porosity in a temporary hillslope wetland underlain by Archaean Lanseria gneiss in South Africa. Final comments are made regarding areas where quantification of porosity is problematic.Keywords: porosity; void ratio; vadose zone; effective porosity; fractal; microstructure; porosimetry; ferricrete; temporary hillslope wetland IntroductionAlbeit a straightforward concept (how hard can determining the ratio of voids to solids possibly be?), quantification of porosity is often significantly simplified. The importance of porosity in hydrology as a primary input parameter in almost all subsequent calculations is overlooked and the parameter is estimated without any validation, resulting in significant unquantifiable errors in hydraulic parameters. However, the simple percentage value of porosity is only one such aspect. The importance of type, scale and connectivity of porosity is commonly understood, but rarely evaluated in significant detail.A detailed discussion in Miller and Gray (2002) on the status of groundwater research accentuates a number of aspects requiring more research and where our understanding is often not sufficient. Reference is made particularly to preferential flow paths such as fractures and the resulting complicated accounting of interactions between these fractures and the flow through the primary pore space. They continue to elaborate on the difficulty of accounting for scale ranging from molecular to regional field problems. Fractured systems are singled out due to the difficulty in characterising and modelling fractures with available methods and because of their interaction with the porous matrix.As this is a review paper, basic concepts will be described concisely for the sake of cross-disciplinary agreement. It is impossible to cover the whole range of methods applicable to porosity. The purpose of this paper is primarily to summarise considerations in the quantification of porosity, to review recent advances in the quantification of porosity, to ap...

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Transport phenomena in hydrothermal systems; the nature of porosity

Cited by 283 publications

References 0 publications

Mathematical simulation of magma-hydrothermal activity associated with the 1977 eruption of Usu volcano

Mathematical simulation of magma-hydrothermal activity associated with the 1977 eruption of Usu volcano

Ridge-Flank Alteration of Upper Ocean Crust in the Eastern Pacific: Synthesis of Results for Volcanic Rocks of Holes 504B and 896A

Porosity Reviewed: Quantitative Multi-Disciplinary Understanding, Recent Advances and Applications in Vadose Zone Hydrology

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