Layer-By-Layer Mechanism of Smectite Illitization and Application to a New Rate Law

Bethke, Craig M.

doi:10.1346/ccmn.1986.0340204

Cited by 129 publications

(55 citation statements)

References 43 publications

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“…For illitization, however, they underestimate the amount of time required for conversion, usually because smectite reacts more slowly as it becomes progressively more illitic. A kinetic rate law introduced by Bethke and Altaner (1986) takes this phenomenon into account and is consistent with illitization rates observed from a number of basins. Adopting the same formulation and estimating the amount of time required to convert smectite to >95% illite at 0 o C, this approach yields a time estimate of ~9.2 Ga.…”

Section: Smectite Clayssupporting

confidence: 68%

“…The thermal history of this formation is well constrained, yielding time-temperature integral curves Using reaction kinetics to estimate TTI thresholds for illitization is more difficult because of the nature of the reaction mechanism. The temperature dependence of illitization has been investigated experimentally and derived by fitting kinetic equations to illite/smectite mineralogy in terrestrial sedimentary basins (Eberl and Hower, 1976;Bethke and Altaner, 1986;Velde and Vasseur, 1992). As is the case for opal-CT conversion, high temperature experimental reaction kinetics do not extrapolate well to low temperature.…”

Section: Smectite Claysmentioning

confidence: 99%

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Juvenile chemical sediments and the long term persistence of water at the surface of Mars

Tosca

Knoll

2009

Earth and Planetary Science Letters

133

124

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Chemical sediments and the aqueous alteration products of volcanic rocks clearly indicate the presence of water, at least episodically, at the martian surface. Compared to similar materials formed on the early Earth, however, martian deposits are juvenile, or diagenetically under-developed. Here we examine the role of water in facilitating various diagenetic reactions and evaluate the predicted effects of time and temperature for aqueous diagenesis on Mars.Using kinetic formulations based on terrestrial sedimentary geology, we quantify the integrated effects of time and temperature for a range of possible burial and thermal histories of precipitated minerals on Mars. From this, we estimate thresholds beyond which these precipitates should have been converted to the point of non-detection in the presence of water. Surface water has been shown to be at least episodically present in recent times. Nonetheless, the integrated duration of aqueous activity recorded over geologically long intervals by hydrated amorphous silica, smectite clays and Fe-sulfate minerals suggest that where these minerals occur water did not persist much beyond their initial deposition. This geochemical conclusion converges with geomorphologic studies that suggest water limitation during the late Noachian-Hesperian peak of potentially habitable environments on Mars should address the timescales on which liquid water has persisted and the timing of aqueous episodes relative to major planetary events.

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Section: Smectite Clayssupporting

confidence: 68%

Section: Smectite Claysmentioning

confidence: 99%

Juvenile chemical sediments and the long term persistence of water at the surface of Mars

Tosca

Knoll

2009

Earth and Planetary Science Letters

133

124

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“…Several factors contribute to this relationship. First, higher abundance of expandable (smectite) layers in illite-smectite results in higher rates of illitization (Bethke and Altaner, 1986). Second, the 42% smectite layer abundance value is the "magic number": above this threshold the rate of illitization dramatically increases because less fixed potassium is required to transform illite-smectite into illite (Środoñ, et al, 1986).…”

Section: Sediment Mineralogy From Xrd Analysis and Indices Of Weathermentioning

confidence: 99%

Climate in continental interior Asia during the longest interglacial of the past 500 000 years: the new MIS 11 records from Lake Baikal, SE Siberia

et al. 2010

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Abstract.A synthesis of paleoclimate responses from Lake Baikal during the MIS 11 interglacial is presented based on proxy records from two drill sites 245 km apart. BDP-99 is located in vicinity of the delta of the major Baikal tributary, whereas the BDP-96 site represents hemipelagic setting distant from riverine influence. The comparison of thicknesses of interglacial intervals in these contrasting depositional settings confirms the extended ca. 33-kyr duration of the MIS 11 interglacial. The new BDP-99 diatom biostratigraphic record matches that of the BDP-96-2 holostratotype and thus allows establishing establishes robust correlation between the records on the same orbitally-tuned timescale.The first detailed MIS 11 palynological record from the BDP-99 drill core indicates the dominance of boreal conifer (taiga) forest vegetation in the Baikal region throughout the MIS 11 interglacial, since at least 424 ka till ca. 396 ka. The interval ca. 420-405 ka stands out as a "conifer optimum" with abundant Abies sibirica, indicative of climate significantly warmer and less continental than today. The closest Baikal analog to this type of vegetation in the history of the current Holocene interglacial is at ca. 9-7 ka. The warm conifer phase lasted for ca. 15 kyr during MIS 11 interrupted by two millennial-scale cooling episodes at ca. 411-410 and 405-404 ka. Reconstructed annual precipitation of 450-550 mm/yr during the MIS 11 interglacial is by ca. 100 mm higher than during the Holocene; regional climate was less continental with warmer mean temperatures both in summer and in winter.Correspondence to: A. A. Prokopenko (sasha@geol.sc.edu) At both drill sites, the two-peak structure of the MIS 11 diatom abundance profiles reflects the orbital signature of precession in the interglacial paleoclimate record of continental Eurasia. MIS 11 interglacial was characterized by the sustained high level of primary production and accumulation of autochthonous organic matter at both study sites. The responses of paleoclimate-sensitive indices in the mineralogy of the MIS 11 sediments in BDP-96-2 are consistent with those during the Holocene. Illitization of secondary clay minerals in the Baikal watershed was an important process, but it appears to have been subdued during the first half of the MIS 11, apparently due to elevated humidity and muted seasonality of regional climate. Past interglacials as potential analogs to modern and future climatesThe ability to predict future changes in global climate is essential for policymaking today and for human well-being in future, it relies on the ability to successfully model climatic conditions known to have existed in the past. Instrumental and even historic records of past climates do not extend beyond the very late portion of the current Holocene interglacial, which lasted since ca. 11.7 ka. To gain a better understanding of the climate of earlier periods, different geologic archives are studied for paleoclimate proxy records.The dominant paradigm in paleoclimate research recognizes...

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“…Illitization appears to be gradual and progressive, however, and the intermediate products of the transformation consist of illite-smectite (I/S) mixed-layer clays (Dunoyer de Segonzac, 1970;Reynolds and Hower, 1970;Ahn and Peacor, 1986). I/S mixed-layer crystallites normally reach proportions of 70%−80% illite at temperatures of 90°−140°C Freed and Peacor, 1989b), but the socalled completion temperature (100% illite) can extend beyond 200°C if kinetic factors are appropriate (Eberl and Hower, 1976;Hoffman and Hower, 1979;Bethke and Altaner, 1986;Velde and Vasseur, 1992;Huang et al, 1993).…”

Section: Thematic Backgroundmentioning

confidence: 99%

Clay mineralogy and clay geochemistry in the vicinity of the décollement zone, northern Barbados Ridge

Underwood¹,

Deng²

1997

Proceedings of the Ocean Drilling Program, 156 Scientific Results

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Fine-grained sediments recovered during Leg 156 of the Ocean Drilling Program contain assemblages of clay minerals that change considerably with depth. Key structural and stratigraphic features within the toe of the northern Barbados accretionary prism include the basal décollement and a sharp boundary between lithologic Units II and III; this lithologic boundary occurs within the décollement zone. We analyzed three size fractions (4−8 µm, 1−4 µm, and <1 µm) by X-ray diffraction and obtained chemical data from the <1-µm size fractions by scanning electron microscopy coupled with energy dispersive spectroscopy. Relative proportions of expandable clay minerals increase significantly, but erratically, near the top of the décollement zone. Proportions of discrete smectite and smectite-rich illite/smectite (I/S) mixed-layer clays decrease steadily down the décolle-ment zone. The base of the décollement zone is characterized by unusually high concentrations of illite. These changes in clay mineralogy influence the shear strength of claystones at the deformation front and help control the position of the décollement.Relative abundances of illite within all lithofacies units increase in coarser size fractions, and this trend is consistent with a detrital source. Kaolinite does not display any systematic partitioning within Unit II, but its proportions increase in the finer size fractions within Unit III. The smectite content of Unit II increases with decreasing grain size; Unit III shows the opposite trend between particle size and % smectite. Bentonite-like samples probably originated through in situ alteration of disseminated volcanic ash, but we believe that the pyroclastic material was mixed into a background sediment that already contained abundant detrital smectite. Illitic mixed-layer clays within the underthrust domain (Unit III) also appear to be detrital in origin. Correlations among both % smectite and % kaolinite and most major-element oxides are statistically significant, but correlations for illite are not. Expandable clays vary considerably in their chemical make-up; the most common type appears to be a Mg-poor, K-rich, Fe-Al-beidellite. We rely upon actualistic provenance connections for late Quaternary clays to guide our interpretations of Miocene and Oligocene sediment dispersal. If these analogues are valid, then the proto-Orinoco and protoAmazon Rivers were the most important detrital sources for the older hemipelagic and turbidite deposits of Barbados Ridge.

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Layer-By-Layer Mechanism of Smectite Illitization and Application to a New Rate Law

Cited by 129 publications

References 43 publications

Juvenile chemical sediments and the long term persistence of water at the surface of Mars

Juvenile chemical sediments and the long term persistence of water at the surface of Mars

Climate in continental interior Asia during the longest interglacial of the past 500 000 years: the new MIS 11 records from Lake Baikal, SE Siberia

Clay mineralogy and clay geochemistry in the vicinity of the décollement zone, northern Barbados Ridge

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