Volatile production and transport in regional metamorphism

Walther, John V.; Orville, Philip M.

doi:10.1007/bf00371516

Cited by 322 publications

(143 citation statements)

References 5 publications

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“…thermexcell.com). Figure 9 compares profiles in T max obtained for three different country rocks, all other parameters being equal: (1) a dry sediment; (2) a sediment with water locked in hydrous minerals and dehydration between 400 and 600 • C absorbing 160 kJ/kg (Walther and Orville, 1982); (3) a watersaturated sediment as described above. The effect of heat being absorbed by water volatilization is to decrease temperatures and the thickness of aureoles.…”

Section: Water In the Country Rockmentioning

confidence: 99%

Factors Affecting the Thickness of Thermal Aureoles

Annen

2017

Front. Earth Sci.

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Intrusions of magma induce thermal aureoles in the country rock. Analytical solutions predict that the thickness of an aureole is proportional to the thickness of the intrusion. However, in the field, thermal aureoles are often significantly thinner or wider than predicted by simple thermal models. Numerical models show that thermal aureoles are wider if the heat transfer in the magma is faster than in the country rock due to contrasts in thermal diffusivities or the effect of magma convection. Large thermal aureoles can also be caused by repeated injection close to the contact. Aureoles are thin when heat transfer in the country rock is faster than heat transfer within the magma or in case of incrementally, slowly emplaced magma. Absorption of latent heat due to metamorphic reactions or water volatilization also affects thermal aureoles but to a lesser extent. The way these parameters affect the thickness of a thermal aureole depends on the isotherm under consideration, hence on which metamorphic phase is used to draw the limit of the aureole. Thermal aureoles provide insight on the dynamics of intrusions emplacement. Although available examples are limited, asymmetric aureoles point to magma emplacement by over-accretion for mafic cases and by under-accretion for felsic cases, consistent with geochronological data.

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Section: Water In the Country Rockmentioning

confidence: 99%

Factors Affecting the Thickness of Thermal Aureoles

Annen

2017

Front. Earth Sci.

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“…At this scale the average rock hydraulic behavior is well described using the Darcy law: (Walther and Orville, 1982), and P is the fluid pressure (Pa). The pressure gradient depends on driving forces such as buoyancy, topography and pressuredriven fluid expulsion caused by either transient changes of porosity or fluid production (i.e., magmatic and/or metamorphic).…”

Section: Multiscale Fluid Flow Analysismentioning

confidence: 99%

Estimating the local paleo-fluid flow velocity: New textural method and application to metasomatism

Sizaret

Branquet

Gloaguen

et al. 2009

Earth and Planetary Science Letters

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Estimating the local paleo-fluid flow velocity: New textural method and application to metasomatism. Earth and Planetary Science Letters, Elsevier, 2009, 280 (1-4) Finally, a two-stage tectono-hydrodynamic model is proposed for the metsomatism. The first stage is genetically linked to the sill injection, and the second is characterized by a wider event with hydrothermal flow passing along the leucogranite sills.

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“…However, in recent years, the ubiquity of a metamorphic fluid phase in time and space has been questioned using physical, petrological and geochemical arguments (Hoernes and Friedrichsen, 1978;Walther and Orville, 1982;Thompson, 1983;Yardley and Baltatzis, 1985;Heinrich, 1986). These arguments have led to the alternative view that a free fluid phase is only present for limited periods of time, i.e.…”

Section: Copyright the Mineralooical Societymentioning

confidence: 99%

“…Thus equation (2) can only be applied to fluid films with a thickness exceeding 50 nm 5 #m (depending on the exact value of 2). Using this range of limiting values, the maximum value of apparent viscosity which can be calculated from equation (2) is r/f ~_ 3r/b for typical metamorphic conditions [e = 20 (Helgeson and Kirkham, 1974), ( --15 mV for a quartz-water interface (Lidstr6m, 1968, p. 101), x = 10 -6 ohmcrn-a, and qb = 10-3 Poise (Walther and Orville, 1982)]. Developments in the theory of electrokinetic flow now enable the viscosity of fluid films with widths as low as the Debye double layer thickness to be predicted (fif/2 >~ 1) (Rice and Whitehead, 1965;Levine et al, 1975a, b;Olivares et al, 1980).…”

Section: Diffi4sion In Fluid Filmsmentioning

confidence: 99%

The catalysis of mineral reactions by water and restrictions on the presence of aqueous fluid during metamorphism

1986

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ABSTRACT, The problems of characterizing intergranular regions and of estimating rates of intergranular diffusion in metamorphic rocks are discussed. Intergranular regions can be anhydrous, hydrated but undersaturated with H20, or saturated with H20, but only in the latter case can a free aqueous fluid phase be present. Estimates of intergranular diffusion coefficients (D mR) at 550 ~ derived from a variety of published experimental work, vary from ~ 10 -8 m 2 s -1 for diffusion of species through an intergranular fluid film to ~< 4 • 10-24 m 2 s 1 for diffusion of SiO2 or O in anhydrous grain boundaries in quartzite. Estimates of D mR for hydrated grain boundaries vary from ~ 10 -13 m 2 s -1 to ~ 10 -zl m 2 s 1; the concentration of H20 in the grain boundaries and the identity of the diffusing species (generally unknown) may be important controlling factors, and there exists the possibility of a spectrum of values between these two extremes.Using available kinetic data it is shown that a free aqueous fluid could never have been present in parts of the basement terrane of the Sesia Zone (Western Alps) during uplift from the eclogite facies, except possibly late in the cooling history. The breakdown of sodic pyroxene+ quartz occurred in response to the localized infiltration of catalytic aqueous fluid, possibly over a time interval as short as 6-6000 a, and possibly under conditions remote from equilibrium. H20-present conditions during a dehydration reaction in metapelites of the Adula nappe (central Alps) could also have been of short duration. These examples are consistent with a model in which basement rocks at deep crustal levels are dry for long periods of time and in which the development of equilibrium mineral assemblages and microstructures generally occurs over relatively short periods of time under transitory fluid-present conditions (caused by devolatilization and/or infiltration).

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Volatile production and transport in regional metamorphism

Cited by 322 publications

References 5 publications

Factors Affecting the Thickness of Thermal Aureoles

Factors Affecting the Thickness of Thermal Aureoles

Estimating the local paleo-fluid flow velocity: New textural method and application to metasomatism

The catalysis of mineral reactions by water and restrictions on the presence of aqueous fluid during metamorphism

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