Smectite to Illite Conversion Rates: Effects of Solution Chemistry

Roberson, Herman E.

doi:10.1346/ccmn.1981.0290207

Cited by 154 publications

(88 citation statements)

References 9 publications

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“…Temperature is the most important factor in the smectite-to-illite transition, but the reaction is affected by many other internal and external variables, such as hydraulic and differential burial pressures, host-rock porosity and permeability, water-rock ratios, pore-water chemistry, abundance of specific interlayer cations in the smectite, bulk host-rock mineralogy, the nature of lithologic interbedding, chemical composition of the precursor smectite, content of organic matter, and reaction time Eberl and Hower, 1977;Eberl, 1978;Roberson and Lahann, 1981;Bruce, 1984;ColtenBradley, 1987;Yau et al, 1987;Velde and Iijima, 1988;Velde and Espitalie, 1989;Whitney, 1990). Empirical correlations of I/S ratios with burial temperature and heating time suggest that the progress of reactions can be modeled according to kinetic rate laws (Eberl and Hower, 1976;Pytte and Reynolds, 1989).…”

Section: Smectite-illite Diagenesismentioning

confidence: 99%

Sediment Geochemistry, Clay Mineralogy, and Diagenesis: A Synthesis of Data from Leg 131, Nankai Trough

Underwood¹,

Pickering²,

Gieskes³

et al. 1993

Proceedings of the Ocean Drilling Program

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This paper presents a synthesis of data from X-ray diffraction analyses of clay minerals and X-ray fluorescence analyses of bulk mudstones from Ocean Drilling Program Site 808. The samples come from three closely spaced holes drilled through the toe of the Nankai accretionary prism offshore Shikoku, Japan. Detrital assemblages of clay minerals are unusually uniform throughout the Nankai trench-wedge facies. Illite is the most abundant detrital clay mineral, followed by chlorite, smectite, and traces of kaolinite. Relative percentages of smectite increase within the upper subunit of the Shikoku Basin stratigraphy. This subunit contains abundant layers of volcanic ash, and the corresponding change in clay mineralogy probably was caused by synvolcanic weathering in source areas during the Pliocene, together with in-situ alteration of disseminated glass shards within the Shikoku Basin.At a depth of ~555 mbsf, the detrital and/or authigenic smectite component begins its transformation to illite/smectite mixed-layer clay. With increasing depth below this horizon there is a monotonic increase in illite interlayers. The onset of illitization occurs at an estimated temperature of ~65°C. Ordered (R = 1) illite/smectite interlayering first appears at depths of -1220 mbsf (<2-µm size fraction) and -1100 mbsf (<0.2-µm size fraction). The depth interval of the smectite-to-illite transformation coincides with a reduction in pore-water chlorinity; however, the absolute abundance of smectite appears to be insufficient to account for the changes in aqueous chemistry via in-situ dehydration reactions. Instead, significant volumes of diluted pore water probably were transported to Site 808, either from sources located deeper in the accretionary prism (where bulk mudstone porosities are lower) or from lateral sources where mudstones originally deposited in the Shikoku Basin may contain higher percentages of smectite. Significantly, we did not detect any anomalies in clay mineralogy or clay-mineral diagenesis within or near the décollement zone (945-964 mbsf).X-ray fluorescence analyses show that hemipelagic muds and mudstones at Site 808 are chemically uniform throughout most of the section. There are no geochemical perturbations, for example, within the décollement zone. Data from interbeds of volcanic ash demonstrate that the chemical effects of mud/ash dissemination and/or in-situ alteration of pyroclastic material are limited. In addition, ash layers are chemically heterogeneous within Unit III and Subunit IVa, which indicates that tephra was transported from a variety of andesitic to rhyolitic sources on the Japanese Islands during the Pliocene. In contrast, Miocene rocks of Unit V display a clear chemical divergence (little mixing) between rhyolitic tuffs and interbeds of multicolored mudstone.The most significant geochemical anomaly at Site 808 occurs well below the décollement zone between 1087 and 1111 mbsf. Variegated mudstones in this interval contain unusually high ratios of MgO/Al 2 O 3 , Fe total /Al 2 O 3 , Mn...

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Section: Smectite-illite Diagenesismentioning

confidence: 99%

Sediment Geochemistry, Clay Mineralogy, and Diagenesis: A Synthesis of Data from Leg 131, Nankai Trough

Underwood¹,

Pickering²,

Gieskes³

et al. 1993

Proceedings of the Ocean Drilling Program

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“…The kinetics of the smectite to illite reaction during shale diagenesis have been studied extensively using experimental techniques (Eberl and Hower, 1976;Roberson and Lahann, 1981;Inoue, 1983;Howard and Roy, 1983;Whitney and Northrop, 1988;Whitney, 1990). Huang et al (1991) have shown that illite/smectite composition versus depth profiles can be calculated using an experimentally derived kiCopyright 9 1993, The Clay Minerals Society netic model assuming knowledge of pore fluid K concentration.…”

Section: Introductionmentioning

confidence: 99%

Experimental Determination of the Rates of Precipitation of Authigenic Illite and Kaolinite in the Presence of Aqueous Oxalate and Comparison to the K/Ar Ages of Authigenic Illite in Reservoir Sandstones

Small

1993

Clays and clay miner.

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Abstract--The importance of precipitation rate as an effective control on illite and kaolanite formation during diagenesis has been examined by measuring precipitation rates, from A1 fluid concentration, in a Dickson fluid-sampling vessel at 160~ ~ and 500 bars (50 MPa). These experiments are considered to be analogues of the precipitation of clays in sandstones from porewaters containing dissolved carboxylic acids, which have a transient stability and may influence aluminosilicate solubility. Precipitated illite had a lath-shaped morphology and its composition was consistent with authigenic iUite in sandstones. Kaolinite formed tabular rather than vermicular shaped crystals. Kaolinite precipitation rate was two orders of magnitude faster than iUite precipitation and was rate-limited by the decomposition of oxalate; kaolinite formation should be equilibrium-controlled at virtually all stages of burial. Extrapolation of illite precipitation rate to burial temperatures indicates that the first appearance of illite in a burial sequence may be kinetically controlled. A model of illite precipitation based on these experimental results has been used to predict the time required to precipitate illite during burial of a sandstone, taking into account temperature changes during burial. For northern North Sea examples, a predicted illitization threshold of -60~ occurring at 60-80 Ma corresponds to the observed initiation of authigenic illite precipitation. Times of around 2-5 Ma would be required to reach a 98% approach to equilibrium at this threshold. The main phase of illite precipitation in the northern North Sea basin is a later, hydrologically controlled event (30-50 Ma). Equilibrium would be approached in around 0.1 Ma during this phase, which is consistent with the narrow illite K/Ar age range (1-5 Ma) recorded for some sequences.

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“…During the transformation, exchangeable cations such as Na + and Ca 2 § in the interlayer of montmorillonite are replaced by K § from the pore solution, and the K + is gradually fixed. Eberl and Hower (1976) and Roberson and Lahann (1981) studied the structural change from smectite to illite in the laboratory from a kinetic point of view. The effects of interlayer cations on the reaction of montmorillonite to interstratified phases were also examined Copyright 9 1983, The Clay Minerals Society by Eberl (1978aEberl ( , 1978b.…”

Section: Introductionmentioning

confidence: 99%

Potassium Fixation by Clay Minerals during Hydrothermal Treatment

Inoue

1983

Clays and clay miner.

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Abstract--The amount of K fixed in K-and Ca-saturated montmodUonite, vermiculite (trioctahedral), rectorite-type and IMII-ordered mica/montmorillonites was measured as a function of time (1-64 days), temperature (25~176 pH (6.0, 9.7, and 10.7), and K-concentration (0.02 and 1.0 M) in solution. The amount of K fixed by the clays generally increased with increasing temperature, pH, and K-concentration and reached saturation in response to each experimental condition in 5 or 6 days. The K-montmorillonite and K-vermiculite fixed considerable amounts of K even at 25~ Fixed K in moutmoriUonite increased with an increase of the layer charge which is also influenced significantly by the interlayer cation, In detail, the behavior in K-fixation was specific to each clay.The type of structural transformation with K-fixation was different for each clay. In montmorillonite, especially, the type of transformation was related to the cationic composition of the system; in K homoionic system, montmorillonite transformed rapidly into iUite/montmorillonite with about 40% expandable layers at 300~ and in a mixed cation system with Ca and K, it reacted gradually to random illite/montmorillonites with increasing temperature. These data indicate that the cation-exchange process of a natural pore solution plays an important role in the gradual transformation of detrital montmoriUonite to illite.

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Smectite to Illite Conversion Rates: Effects of Solution Chemistry

Cited by 154 publications

References 9 publications

Sediment Geochemistry, Clay Mineralogy, and Diagenesis: A Synthesis of Data from Leg 131, Nankai Trough

Sediment Geochemistry, Clay Mineralogy, and Diagenesis: A Synthesis of Data from Leg 131, Nankai Trough

Experimental Determination of the Rates of Precipitation of Authigenic Illite and Kaolinite in the Presence of Aqueous Oxalate and Comparison to the K/Ar Ages of Authigenic Illite in Reservoir Sandstones

Potassium Fixation by Clay Minerals during Hydrothermal Treatment

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