Silica activity and the smectite-illite reaction

Abercrombie, Hugh J.; Hutcheon, Ian; Bloch, John; Caritat, Patrice de

doi:10.1130/0091-7613(1994)022<0539:saatsi>2.3.co;2

Cited by 101 publications

(59 citation statements)

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“…High activity of silica is required for crystallization of clinoptilolite relative to illite. Abercrombie et aL (1994) noted that the rate of illitization is controlled by silica activity, which in turn is controlled by the rate of precipitation of silica. I-S formation parallels that of maturation of organic material (e.g., Lindgreen et al, 1991).…”

Section: Comparison Of Illitization Rates In Coeval Bentonites and Shmentioning

confidence: 99%

“…The sequences of phases from smectite to illite involve metastable clays, which react following the Ostwald step rule (e.g., Essene and Peacor, 1995). The rate of transformation may therefore be affected by many variables, including temperature, fluid/rock ratio, and fluid composition (Small, 1993;Velde and Vasseur, 1992;Aja et al, 1991;Huang et al, 1993;Abercrombie et al, 1994), i.e., by any variable affecting reaction rate which promotes reaction of a metastable system toward the stable system.…”

Section: Introductionmentioning

confidence: 99%

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Transmission Electron Microscopy Study of Conversion of Smectite to Illite in Mudstones of the Nankai Trough: Contrast with Coeval Bentonites

Masuda

Peacor

Dong

2001

Clays and clay miner.

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Abstract~lay minerals in shales from cores at Site 808, Nankai Trough, have been studied using X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), and analytical electron microscopy (AEM) to compare the rates and mechanisms of illitization with those of coeval bentonites, which were described previously. Authigenic K-rich smectite having a high Fe content (--7 wt. %) was observed to form directly as an alteration product of volcanic glass at a depth of --500 meters below seafloor (mbsf) with no intermediate precursor. Smectite is then largely replaced by Reichweite, R, (R = 1) illitesmectite (I-S) and minor illite and chlorite over depths from --550 to --700 mbsf. No further mineralogical changes occur to the maximum depth cored, -1300 m. Most smectite and I-S in shales are derived from alteration of glass, rather than being detrital, as is usually assumed. Discrete layer sequences of smectite, I-S, or illite coexist, indicating discontinuities of the transformation from smectite to (R = 1) I-S to illite. Authigenic Fe-rich chlorite forms concomitantly with I-S and illite, with the source of Fe from reactant smectite.Smectite forms from glass with an intermediate precursor in coeval bentonites at approximately the same depth as in shales, but the smectite remains largely unchanged, with the exception of exchange of interlayer cations (K ---) Na ~ Ca) in response to formation of zeolites, to the bottom of the core. Differences in rates of illitization reflect the metastability of the clays. Temperature, structure-state, and composition of reactant smectite are ruled out as determining factors that increase reaction rates here, whereas differences in water/rock ratio (porosity/permeability), Si and K activities, and organic acid content are likely candidates.

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Section: Comparison Of Illitization Rates In Coeval Bentonites and Shmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transmission Electron Microscopy Study of Conversion of Smectite to Illite in Mudstones of the Nankai Trough: Contrast with Coeval Bentonites

Masuda

Peacor

Dong

2001

Clays and clay miner.

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“…The species included Fe(II), total HCO 3 -and Eh. SiO 2 (aq) was set at saturation with respect to opal-CT, which is characteristic of many shallow groundwaters (Abercrombie et al, 1994;Apps, 2004). Total HCO 3 -was calculated from the entered "free" HCO 3 -or alkalinity, see Section 3.4.3 below.…”

Section: Concentration Of Major Constituents In Potable Groundwatermentioning

confidence: 99%

Research Project on CO2 Geological Storage and Groundwater Resources: Water Quality Effects Caused by CO2 Intrusion into Shallow Groundwater

Birkhölzer¹,

Apps²,

Zheng³

et al. 2008

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“…Finally, the chemical properties of porewater, with which the clays interact, seldom can be characterized fully. Yet, if mineral reaction mechanisms and controls are to be unraveled, the whole bulk-rock system must be documented and the variables within the system assessed for their contribution to the control on mineral reaction mechanisms (Abercrombie et al 1994;Pollastro 1994).…”

Section: Background and Approachmentioning

confidence: 99%

Comparison of the Mineralogical and Chemical Composition of 2 Shales from the Western Canada Sedimentary Basin and the United States Gulf Coast

Caritat

Bloch²,

Hutcheon

et al. 1997

Clays and clay miner.

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Abstract--The mineralogy and geochemistry of shales reflect the composition of the initially deposited precursor mud, subsequently modified by diagenetic processes. To see if significant geochemical differences exist between shales that mainly owe their present-day composition to either deposition or diagenesis, we compare the published mineralogical, bulk and clay-fraction geochemical, and clay-fraction O-isotopic compositions of 2 shales. One shale is from the Western Canada Sedimentary Basin (WCSB), and its composition mainly reflects primary (depositional) chemical and mineralogical variations (smectitic to illitic illite/smectite) within this unit. The other shale is from the United States Gulf Coast (USGC), and its composition mainly reflects mixed-layer illite/smectite (US) diagenesis of deposited smectitic clay material. The chemical and mineralogical trends of WCSB and USGC shales, including one of increasing illite content in US with depth or maturity, are essentially indistinguishable, in both bulk shale and clay fraction, despite the contrasting genetic interpretations for the origin of the contained US. Thus, similar mineralogical and chemical trends with depth or temperature can result either from inherited depositional compositional heterogeneity of the sediment, from burial metamorphism of shale or a combination of both. Interestingly, the O-isotopic compositions of the clay fractions from the WCSB and USGC are significantly different, a fact that reflects original clay formation from source material and water of quite different isotopic compositions. The discrimination between depositional and diagenetic contributions to shale composition continues to pose challenges, but a combination of bentonite, illite polytype, clay isotopic and trace and rare earth elemental analyses together with illite age analysis holds promise for future work;

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Silica activity and the smectite-illite reaction

Cited by 101 publications

References 0 publications

Transmission Electron Microscopy Study of Conversion of Smectite to Illite in Mudstones of the Nankai Trough: Contrast with Coeval Bentonites

Transmission Electron Microscopy Study of Conversion of Smectite to Illite in Mudstones of the Nankai Trough: Contrast with Coeval Bentonites

Research Project on CO2 Geological Storage and Groundwater Resources: Water Quality Effects Caused by CO2 Intrusion into Shallow Groundwater

Comparison of the Mineralogical and Chemical Composition of 2 Shales from the Western Canada Sedimentary Basin and the United States Gulf Coast

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