The mechanism of the reaction 1 tremolite+3 calcite+2 quartz =5 diopside+3 CO2+1 H2O: results of powder experiments

Dachs, Edgar; Metz, Paul

doi:10.1007/bf00371382

Cited by 23 publications

(16 citation statements)

References 21 publications

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“…Mineral powders are commonly used to determine reaction rates experimentally (Dachs and Metz 1988;Heinrich et al 1986Heinrich et al , 1989Kase and Metz 1980;Kridelbaugh 1973;Lüttge andMetz 1991, 1993;Schramke et al 1987;Tanner et al 1985). Mineral powder reactants, though, have much greater surface areas than rocks do, resulting in fast reaction rates.…”

Section: Discussionmentioning

confidence: 99%

“…Kinetic models of metamorphic reactions generally fall within three broad categories: heat-fl ow controlled, surface controlled, or diffusion controlled (Fisher 1978;Walther and Wood 1984;Rubie and Thompson 1985;Lasaga 1986Lasaga , 1998Ridley and Thompson 1986;Dachs and Metz 1988). Since all these experiments were conducted at constant temperature, changes in heat fl ow were not a consideration.…”

Section: Extent Of Reaction With Timementioning

confidence: 99%

“…Laboratory studies of reaction rates are generally performed with the use of mineral powders to approximate rock assemblages (e.g., Dachs and Metz 1988;Heinrich et al 1986Heinrich et al , 1989Kase and Metz 1980;Kridelbaugh 1973;Lüttge and Metz 1991;Schramke et al 1987;Tanner et al 1985). Those studies were successful in describing mechanisms and rates of reactions, but the large porosities and surface areas of powders in direct contact with an abundant fl uid phase differ considerably from low-permeability rocks (Lüttge and Metz 1993).…”

Section: Introductionmentioning

confidence: 98%

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Experimental investigation of the breakdown of dolomite in rock cores at 100 MPa, 650-750 C

DeAngelis

Labotka

Cole

et al. 2007

American Mineralogist

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The kinetics of the breakdown reaction dolomite = periclase + calcite + CO 2 were investigated using cores of dolomitic marble. Two samples of Reed Dolomite from southwestern Nevada were cut into cylinders approximately 4 × 6 mm in size. The cores were sealed in gold capsules with isotopically enriched water (H 2 18 O or HD 18 O 0.5 16 O 0.5 ). The samples were heated in a cold-seal hydrothermal apparatus to 650-750 °C at 100 MPa for durations ranging from 2-59 days. The cores were then sectioned and examined by EPMA, XRD, and SIMS techniques. All experiments showed some amount of reaction regardless of duration or temperature. Reaction products occurred mainly along grain boundaries, fractures within grains, and along sample edges. Ion images and isotope-ratio analysis indicated that reaction products exchanged with infi ltrating fl uids. Reaction rates were calculated from measured extents of reaction, which were determined from automated EPMA modes. At 700 °C, we measured reaction rates ranging from 3.8 × 10 -14 to 2.3 × 10 -12 mol/mm 2 ·s. The extent of reaction is proportional to the square root of time, suggesting a diffusion-controlled process. A shrinking-core model for the dolomite breakdown reaction fi ts the grain-size data, suggesting that diffusion of H 2 O and CO 2 through the mantle of reaction products controlled the rate. Apparent activation energies for that diffusion are ~283 ± 32 kJ/mol for coarse-grained samples and ~333 ± 36 kJ/mol for fi ne-grained samples. Initial reaction occurred relatively fast near the surface of dolomite grains, but continued diffusion through the reaction products ultimately controlled the rate of dolomite breakdown.

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Section: Discussionmentioning

confidence: 99%

Section: Extent Of Reaction With Timementioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Experimental investigation of the breakdown of dolomite in rock cores at 100 MPa, 650-750 C

DeAngelis

Labotka

Cole

et al. 2007

American Mineralogist

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“…Chemo‐mechanical damage models [e.g., Arson and Pereira , ; Arson et al , ; Chadam et al , ; Dewers and Ortoleva , ; Ortoleva et al , ; Pereira and Arson , ; Zhu and Arson , , ] are limited to ideal microstructures. Studies of reaction mechanisms and kinetics focused on mineral powders, which allowed understanding the influence of pressure, temperature, and fluid composition [ Heinrich et al , ; Tanner et al , ] as well as that of reactant surfaces and nucleation processes on reaction kinetics [ Dachs and Metz , ; Schramke et al , ; Lüttge and Metz , ]. However, models were not applicable to natural systems, due to the large porosities of the powders, the large surface areas of the mineral reactants, and the abundant fluid phases [ Lüttge and Metz , ].…”

Section: Introductionmentioning

confidence: 99%

Chemomechanical evolution of pore space in carbonate microstructures upon dissolution: Linking pore geometry to bulk elasticity

Arson

Vanorio

2015

JGR Solid Earth

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One of the challenges faced today in a variety of geophysical applications is the need to understand the changes of elastic properties due to time‐variant chemomechanical processes. The objective of this work is to model carbonate rock elastic properties as functions of pore geometry changes that occur when the solid matrix is dissolved by carbon dioxide. We compared two carbonate microstructures: porous micrite (“mudstone”) and grain‐supported carbonate (“packstone”). We formulated a mathematical model that distinguishes the effects of microporosity and macroporosity on stiffness changes. We used measures of mechanical and chemical porosity changes recorded during injection tests to compute elastic moduli and compare them to moduli obtained from wave velocity measurements. In mudstones, both experimental and numerical results indicate that bulk moduli change by less than 5%. The evolution of elastic moduli is controlled by macropore enlargement. In packstones, model predictions underestimate changes of elastic moduli with total porosity by 10% to 80%. The total porosity variation is 60% to 75% smaller than the chemical porosity variation, which indicates that pore expansion due to dissolution is counterbalanced by pore shrinkage due to compaction. Packstone elastic properties are controlled by grain sliding. The methodology presented in this paper can be generalized to other chemomechanical processes studied in rocks, such as dislocations, glide, diffusive mass transfer, recrystallization, and precipitation.

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“…Such extrapolations of laboratory-based kinetic data for high temperature (300°-700°C) metamorphic reactions (for example Wood and Walther, 1983;Helgeson and others, 1984;Matthews, 1985;Rubie and Thompson, 1985;Tanner and others, 1985;Lasaga, 1986;Schramke and others, 1987;Dachs and Metz, 1988;Heinrich and others, 1989;Kerrick and Others, 1991;Lüttge andMetz, 1991, 1993;Hacker and others, 1992;Jove and Hacker, 1997;Lüttge and others, 1998;Winkler and Lüttge, 1999, and references therein) are subject to large uncertainties because the reaction mechanisms (see Dachs and Metz, 1988;Metz, 1991, 1993;Hacker and others, 1992; Barnett and Bowman, 1995;Jove and Hacker, 1997;Mosenfelder and Bohlen, 1997;Ganor and Lasaga, 1998;Penn and Banfield, 1999;Zheng and others, 1999;Lasaga and Lüttge, 2001) and controlling parameters (for example affinity for reaction, and reactive surface area) are variable and may not be consistent between the lab and nature. Thus, while the theory of reaction rates and chemical transport in fluid-rock systems has been the topic of extensive study (Aagaard and Helgeson, 1982;Walther and Wood, 1984;Lasaga, 1989Bickle and McKenzie, 1987;Richter and DePaolo, 1987;Baumgartner and Rumble, 1988;Blattner and Lassey, 1989;Lassey and Blattner, 1988;Knapp, 1989;Bickle, 1992;Lasaga and Rye, 1993;…”

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confidence: 97%

Field measurement of high temperature bulk reaction rates I: Theory and technique

Baxter¹,

DePaolo²

2002

American Journal of Science

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Knowledge of metamorphic reaction rates is crucial to accurately interpret rock and mineral chemistry. The local equilibrium assumption, used in geochronology, geothermobarometry, and material flux estimates, requires that local reaction rates among system phases are fast relative to local rates of P-T-X change. Natural metamorphic reaction rates are essentially unknown and difficulties and disagreements exist regarding extrapolations of existing laboratory data to natural conditions. Growing recognition of natural effects that could be attributed to slower reaction rates justifies the need for a field-based quantification of reaction rates to assess the accuracy of lab-based predictions. We describe in detail the theory and methodology of a technique for extracting bulk reaction rates directly from isotopic data derived from natural samples (Baxter and DePaolo, 2000). Reaction rates measured using this technique may be judiciously applied to isotopic exchange or net reaction kinetics in other natural systems. The technique requires collection of whole rock and garnet 87 Sr/ 86 Sr data along a sampling traverse normal to a lithologic contact where there was, prior to metamorphism, a sharp isotopic discontinuity. Garnet data provide information on syn-metamorphic conditions and the time interval for the exchange process. Forward modeling of the reactive transport process using numerical methods and the equations for diffusive reactive transport allow determination of the reaction rate and bulk Sr diffusivity that provides the best fit to the data. Measurement of reaction rates is best constrained if an isotopic step is preserved at the contact, the size of which is directly proportional to the bulk reaction rate. This contribution is intended to serve as a template for future use and development of this technique to acquire natural reaction rate data from metamorphic systems.

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The mechanism of the reaction 1 tremolite+3 calcite+2 quartz =5 diopside+3 CO2+1 H2O: results of powder experiments

Cited by 23 publications

References 21 publications

Experimental investigation of the breakdown of dolomite in rock cores at 100 MPa, 650-750 C

Experimental investigation of the breakdown of dolomite in rock cores at 100 MPa, 650-750 C

Chemomechanical evolution of pore space in carbonate microstructures upon dissolution: Linking pore geometry to bulk elasticity

Field measurement of high temperature bulk reaction rates I: Theory and technique

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