Oxygen isotopic transport and exchange during fluid flow; one-dimensional models and applications

Bowman, John R.; Willett, Sean D.; Cook, Stephen J.

doi:10.2475/ajs.294.1.1

Cited by 116 publications

(113 citation statements)

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“…In this analysis we assume that the composition of vein calcite differs only from that of the fluid by the isotope fractionation factor of 3.8% and that the veins are representative of the composition of the latest fluids, an assumption supported by the observation that vein composition does not appear to vary systematically with vein age or type (Figure 6b). The model solution that best fits the data in a least squares sense is represented by the solid curve in Figure 13 for ductile fault zones throughout the world [Dipple and Ferry, 1992a;Bowman et al, 1994;Cartwright and Buick, 1999] (see Table 3). Thus the volume of fluid necessary to cause the observed alteration falls within the range of global values recorded in fault zones but well exceeds that calculated for pervasive flow through low-grade metamorphic terranes.…”

Section: Modeling Results and Interpretationmentioning

confidence: 99%

“…In some instances, the zone of depletion is a distinct trough bounded on the downstream side by a sharp geochemical front, but in many natural occurrences the geochemical front is broadened and rounded by a variety of physical and chemical processes that are collectively referred to as hydrodynamic dispersion (Figure 12). Dispersion in crustal environments has been attributed to sluggish reaction kinetics between rock and fluid (kinetic dispersion [e.g., Lassey and Blattner, 1988;Bickle, 1992]), heterogeneous fluid flow (kinematic dispersion [e.g., Bowman et al, 1994]) or to simultaneous chemical reactions with coupling between chemical systems (reaction dispersion [Dipple, 1998]). Dispersive effects of diffusion are typically limited to length scales of a few meters or less [Bickle and McKenzie, 1987].…”

Section: Model-derived Constraints For Time-integrated Fluid Flux Andmentioning

confidence: 99%

“…18 O values downward [Dipple and Ferry, 1992b;Bowman et al, 1994]. The magnitude of these shifts is a function of the time-integrated fluid flux and the profile of the geothermal gradient.…”

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confidence: 99%

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New evidence for syntectonic fluid migration across the hinterland‐foreland transition of the Canadian Cordillera

2002

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[1] Oxygen isotope data from syntectonic veins, thrust faults, and wall rocks suggest that fluids infiltrated the Western Ranges of the Rocky Mountain foreland from deeper rocks of the Dogtooth Range during Mesozoic contraction. This signifies the first such evidence for kilometerscale fluid migration at the hinterland-foreland transition of the Canadian Cordillera. Fluid infiltration resulted in isotopic depletion in wall rocks and isotopic disequilibrium between veins (fluid) and their host rocks downstream of a lithologic, structural, and isotopic shift between predominantly siliciclastic (Dogtooth Range) and calcareous (Western Ranges) sequences. The shift corresponds with an average d 18 O that is 3.0% higher in the Western Ranges. In the Dogtooth Range, atypically low carbonate values (15.6% ± 0.8% (VSMOW)), and the consistency with which vein signatures approach the average bulk rock d18 O of individual outcrops indicate fluid buffering by a siliciclastic reservoir and outcrop-scale (10 -100 m) fluid circulation. In contrast, rocks and veins in the Western Ranges exhibit a gradational increase in d18 O that extends !14 km eastward and up section from the isotopic shift and possess values that are below or at the low end of typical carbonate compositions (16.2 -20.9% (VSMOW)). Furthermore, veins systematically exhibit lower oxygen values than their host rocks; this implies that the fluids that entered the Western Ranges were in modest disequilibrium with the rocks through which they flowed. We use a one-dimensional reactive transport model to infer that rocks in the Western Ranges experienced a time-integrated fluid flux of 1.1 Â 10 5 mol H 2 O cm À2 (%2.4 Â 10 6 cm 3 cm À2 ) and sluggish reaction kinetics during the flow event.

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Section: Modeling Results and Interpretationmentioning

confidence: 99%

Section: Model-derived Constraints For Time-integrated Fluid Flux Andmentioning

confidence: 99%

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New evidence for syntectonic fluid migration across the hinterland‐foreland transition of the Canadian Cordillera

2002

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“…The vein containing the grossular-rich garnet in gneiss samples ps157-159 is interpreted to have resulted from advection as in sample 42224(ii), but the X Grt against distance profile is more typical of hydrodynamic dispersion during infiltration (e.g., Bowman et al 1994). Proximal to the vein, Ca alteration of D 2 -related garnet is greatest where plagioclase is in contact with garnet ( Fig.…”

Section: And D 2 Metasomatismmentioning

confidence: 99%

VEIN AND SKARN FORMATION AT THE CANNINGTON Ag Pb Zn DEPOSIT, NORTHEASTERN AUSTRALIA

Roache¹,

Williams²,

Richmond³

et al. 2005

The Canadian Mineralogist

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Synchronous deformation and metamorphism at the Cannington Ag-Pb-Zn deposit, in northeastern Australia, involved a phase of Ca and Mn mobilization that accounts for the distribution of pyroxene-and garnet-bearing rocks, which were preferentially overprinted by sulfide mineralization. Garnet composition and its textural association in relation to three generations of planar fabric (S 1 to S 3 ) show that skarn-related grossular-rich garnet formed in the last garnet-stable event, D 3 . The D 3 Cl-rich biotite in the gneiss is intergrown with garnet in veins, and within skarn rocks is continuous along strike with veins of garnet ± pyroxmangite, hedenbergite or amphibole, which indicates a period of anhydrous through to hydrous metasomatism. Compositional maps show that infiltration extended from alteration fronts through fractures, which indicates the high permeability of S 3 ; these maps and X Grt profiles across skarn-gneiss contacts show that there was large-scale transport of mass by infiltration and varying degrees of hydrodynamic dispersion. Precipitation of oscillatory Ca-and Mn-zoned grossular-rich garnet in veins parallel to veins filled with Cl-rich biotite, in conjunction with the distribution of biotite-filled veins across the deposit, suggest that the mass transfer during D 3 may be responsible for deposit-scale Ca-Mn skarn-like zoning.Keywords: garnet, zoning, metasomatism, skarn, shear zones, veins, Cannington, Australia. SOMMAIREUne déformation et une recristallisation métamorphique synchrones dans le gisement à Ag-Pb-Zn de Cannington, dans le nord-est de l'Australie, a impliqué une mobilisation de Ca et de Mn qui rend compte de la distribution de roches à pyroxène et grenat, qui sont devenues par la suite les hôtes ciblés d'une minéralisation en sulfures. La composition et l'association texturale du grenat aux trois générations de foliation (S 1 à S 3 ) montrent que le grenat lié à la formation du skarn, riche en grossulaire, s'est formé lors du dernier épisode de déformation où le grenat était stable, D 3 . La biotite de la génération D 3 dans le gneiss, riche en Cl, montre une intercroissance avec le grenat en veines, et dans les roches du skarn, montre une continuité le long de la gneissosité avec des veines à grenat ± pyroxmangite, hedenbergite ou amphibole, indications d'une période de métasomatose anhydre à aqueuse. Des cartes de répartition d'éléments montrent que l'infiltration s'est propagée à partir de fronts d'altération le long de fissures, indication d'une grande perméabilité le long de S 3 ; ces cartes et les profils de X Grt perpendiculaires aux contacts skarngneiss montrent qu'il y a eu transfert important de masse par infiltration et par dispersion hydrodynamique à divers degrés. D'après la précipitation de cristaux de grenat à zonation oscillatoire en Ca et Mn dans des veines parallèles aux veines remplies de biotite riche en chlore, ainsi que la distribution de telles veines de biotite de part et d'autre du gisement, le tranfert de masse au cours de l'événement D 3 aurait...

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“…However, sluggish reactions require addition of a term to represent kinetic dispersion effects on the transport process and geochemical fronts tend to be broadened. Such effects on isotope fronts were presented soon after the first papers on combined diffusiveadvective transport, first by Blattner and Lassey (1989), followed up by important contributions from Bickle (1992), Bowman et al (1994) and others. An initially abrupt concentration front (step function) travelling from left to right with advection and diffusion but without reaction.…”

Section: Sharpening Of Reaction Frontsmentioning

confidence: 99%

Sculpting of Rocks by Reactive Fluids

Jamtveit¹,

Hammer²

2012

Geochem Persp

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Oxygen isotopic transport and exchange during fluid flow; one-dimensional models and applications

Cited by 116 publications

References 0 publications

New evidence for syntectonic fluid migration across the hinterland‐foreland transition of the Canadian Cordillera

New evidence for syntectonic fluid migration across the hinterland‐foreland transition of the Canadian Cordillera

VEIN AND SKARN FORMATION AT THE CANNINGTON Ag Pb Zn DEPOSIT, NORTHEASTERN AUSTRALIA

Sculpting of Rocks by Reactive Fluids

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