Mechanism and kinetics of the reaction: 1 dolomite + 2 quartz = 1 diopside + 2 CO2: a comparison of rock-sample and of powder experiments

Lüttge, Andreas; Metz, Paul

doi:10.1007/bf00321217

Cited by 28 publications

(25 citation statements)

References 12 publications

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“…Reduction of the fluid/solid ratios in a closed-capsule environment might slow the reaction rate by limiting the amount of reactants transported through the fluid, but Luttge and Metz (1993) could not observe any difference in the dissolutionprecipitation reaction mechanism for dolomite + quartz decarbonation with a fluid/solid ratio of 1 : 37 compared to an earlier study with a fluid/solid ratio of 1:4 (Luttge and Metz, 1991).…”

Section: Discussioncontrasting

confidence: 65%

Hydrothermal Synthesis of Corrensite: A Study of the Transformation of Saponite to Corrensite

Roberson

Reynolds

Jenkins

1999

Clays and clay miner.

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Abstraet~Hydrothermal synthesis experiments were conducted to study the transition from smectite to corrensite. A mixture of oxides with the bulk composition of corrensite--Na0~4(Si6.aAll.6)(Mg7.sA11:)-O20(OH)~0--was sealed in platinum capsules with 29-37 wt. % water. One set of samples was treated in cold-seal vessels at 500~ and 2 kbar for durations of 2, 3, 6, 12, and 24 h; the other set was treated at 350~ and 2 kbar for periods of 12 to 89 d. X-ray diffraction patterns (XRD) of oriented aggregates from treated products were obtained from ethylene glycol-solvated and air-dried preparations. Samples were also heated to 350~ either in a calibrated muffle furnace, removed and quickly placed in a nitrogen filled chamber on the diffractometer, or were heated at 350~ by using a calibrated heating stage mounted on the diffractometer.Initial mineral assemblages at both temperatures contained only saponite and serpentine. In experiments at 500~ saponite u'ansformed to corrensite within 6 h; in experiments at 350~ the transformation occurred as early as 22 d. Increased experiment times at both temperatures produced increasing amounts of well-crystallized corrensite, as indicated by several well-defined XRD peaks. No evidence of a randomly interstratified chlorite-smectite (C-S) precursor to corrensite was found. The identification of pure smectite, as opposed to highly-expanded randomly interstratified C-S, was possible only when clays were dehydrated on a heating stage on the diffractometer.These results call for a new examination of hydrothermally-altered basalt that has been reported to contain randomly interstratified C-S as an intermediate step in the reaction of smectite to corrensite or chlorite. These results also strengthen the view held by increasing numbers of investigators that corrensite should be regarded as a single phase, not as a mixed-layered phyllosilicate.

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Section: Discussioncontrasting

confidence: 65%

Hydrothermal Synthesis of Corrensite: A Study of the Transformation of Saponite to Corrensite

Roberson

Reynolds

Jenkins

1999

Clays and clay miner.

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“…Nucleation and precipitation rates may have strongly influenced the evolution of the fluid composition in both the inner capsule and the external tube in our experiments. Indeed, it is the balance between dissolution and crystallization rates that determines the shape of the reaction path (Lü ttge and Metz, 1991). However, the concentration oversteps required for nucleation (Petrov et al, 1969;Lü ttge and Metz, 1991) are not well known and may depend on parameters such as temperature, local energy variations or presence of impurities (e.g., heterogeneous nucleation on the gold tube), which were not modeled here.…”

Section: Dissolution Kineticsmentioning

confidence: 98%

“…Indeed, it is the balance between dissolution and crystallization rates that determines the shape of the reaction path (Lü ttge and Metz, 1991). However, the concentration oversteps required for nucleation (Petrov et al, 1969;Lü ttge and Metz, 1991) are not well known and may depend on parameters such as temperature, local energy variations or presence of impurities (e.g., heterogeneous nucleation on the gold tube), which were not modeled here. Growth rate constants for gibbsite (Nagy and Lasaga, 1992), kaolinite (Carroll and Walther, 1990;Nagy et al, 1991), and some other minerals are available in the literature.…”

Section: Dissolution Kineticsmentioning

confidence: 98%

Experimental study and modeling of fluid reaction paths in the quartz–kyanite±muscovite–water system at 0.7GPa in the 350–550°C range: Implications for Al selective transfer during metamorphism

Verlaguet

Brunet

Goffé

et al. 2006

Geochimica et Cosmochimica Acta

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“…The experimental design is similar to that of Lüttge and Metz (1993) in their study of dolomite + quartz stability. Small cores, approximately 4 mm in diameter and 5-7 mm in length, were drilled from each marble sample.…”

Section: Experimental Techniquesmentioning

confidence: 98%

“…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). To investigate kinetic processes under more realistic conditions, we conducted an experimental study that used dolomitic marble as starting material to determine the reaction textures and rates.…”

Section: Introductionmentioning

confidence: 99%

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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Mechanism and kinetics of the reaction: 1 dolomite + 2 quartz = 1 diopside + 2 CO2: a comparison of rock-sample and of powder experiments

Cited by 28 publications

References 12 publications

Hydrothermal Synthesis of Corrensite: A Study of the Transformation of Saponite to Corrensite

Hydrothermal Synthesis of Corrensite: A Study of the Transformation of Saponite to Corrensite

Experimental study and modeling of fluid reaction paths in the quartz–kyanite±muscovite–water system at 0.7GPa in the 350–550°C range: Implications for Al selective transfer during metamorphism

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

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