Authigenic trioctahedral smectites controlling pH, alkalinity, silica and magnesium concentrations in alkaline lakes

Darragi, Fadila; Tardy, Yves

doi:10.1016/0009-2541(87)90074-x

Cited by 66 publications

(62 citation statements)

References 26 publications

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“…This process seems to proceed better in highly saline and alkaline environments (Darragi and Tardy, 1987;Hay et al, 1991). This authigenic mechanism is in agreement with the predominance of multiphase mixtures rather than true solid-solutions belonging to the smectite group minerals (Vali et al, 1993;Petit et al, 1992).…”

Section: Introductionsupporting

confidence: 64%

Chemistry of Mg Smectites in Lacustrine Sediments from the Vicalvaro Sepiolite Deposit, Madrid Neogene Basin (Spain)

Cuevas

Villa

Ramı́rez

et al. 2003

Clays and clay miner.

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The chemical and structural properties of Mg smectites in the Vicálvaro sepiolite deposit have been studied in detail. The characterization was performed on different size-fractions of selected smectitic samples (5À2 mm; 2À1 mm; 1À0.5 mm; <0.5 mm and <0.1 mm). The chemical compositions of individual particles (5À1 mm) and of bulk undifferentiated fine fractions (1À<0.1 mm) were determined by energy dispersive spectroscopy-scanning electron microscopy and interpreted with the aid of X-ray diffraction (XRD) and infrared spectroscopy (IR) methods. The XRD and IR data demonstrate that all of the Mg smectite materials studied are mainly composed of a complex mixture of stevensite, saponite and micatype minerals. Although the presence or absence of saponite cannot be confirmed absolutely, stevensite is a significant component of these Mg smectites. This is proven by the calculated layer charge reduction after the Hofmann-Klemen effect. The results are in close agreement with the suggested mechanism of topotactic overgrowth of stevensite on pre-existing phyllosilicate templates. This characterizes clay diagenesis in saline-lake systems.

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Section: Introductionsupporting

confidence: 64%

Chemistry of Mg Smectites in Lacustrine Sediments from the Vicalvaro Sepiolite Deposit, Madrid Neogene Basin (Spain)

Cuevas

Villa

Ramı́rez

et al. 2003

Clays and clay miner.

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“…Such environments range from wetlands in Brazil (Barbiero et al, 2002;Barbiero et al, 2008), northern Spain (Armenteros et al, 1995) and California (Lee et al, 2004), to lakes and wetlands in central and east Africa (Gac et al, 1977;Darragi and Tardy, 1987;Chamley, 1989;Hover et al, 1999;Hover and Ashley, 2003;Liutkus and Ashley, 2003). In such settings, clay neoformation is commonly associated with CaCO 3 and silica precipitation.…”

Section: Clay Mineral Neoformationmentioning

confidence: 97%

Sediment geochemistry, mineral precipitation and clay neoformation on the Mkuze River floodplain, South Africa

et al. 2010

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“…Geochemical tools were used to identify the source of elements necessary to the formation of the stevensite. Our revised model for stevensite genesis is then compared with other models for lacustrine stevensite in ancient and modern lakes, which are: (1) transformation of detrital minerals into stevensite (Jones and Weir 1983;Jones 1986;Brell et al 1985;Banfield et al 1991), (2) direct primary precipitation of stevensite (Tardy et al 1974;Gac et al 1977;Darragi and Tardy 1987) or stevensite with interlayered kerolite Khoury et al 1982;Hay et al 1986), and (3) the formation of stevensite by epigenesis of diatom frustules (Badaut and Risacher 1983;Risacher 1992).…”

Section: Introductionmentioning

confidence: 98%

Diagenetic transformation of dolomite into stevensite in lacustrine sediments from Jbel Rhassoul, Morocco

Chahi¹,

Duringer²,

Ais³

et al. 1999

Journal of Sedimentary Research

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Stevensite in the Tertiary lacustrine basin of the Jbel Rhassoul in Morocco is used as fuller's earth. Observations of the structure and textures of the deposits provide evidence of diagenetic replacement of sedimentary lacustrine dolomite by stevensite. Carbon and oxygen isotopic compositions confirm the precipitation of primary sedimentary dolomite and the diagenetic formation of secondary stevensite. According to thermodynamic calculations, stevensite is stable at the expense of dolomite in a silica-rich and CO 2 -poor environment. Under such conditions, destabilized detrital illite, chlorite, and palygorskite release Al, Fe, Li, and trace elements, which are incorporated into the structure of stevensite. Compared with other lacustrine stevensite occurrences, the Jbel Rhassoul deposit seems to correspond to a new mode for the formation of diagenetic stevensite after dolomite.

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Authigenic trioctahedral smectites controlling pH, alkalinity, silica and magnesium concentrations in alkaline lakes

Cited by 66 publications

References 26 publications

Chemistry of Mg Smectites in Lacustrine Sediments from the Vicalvaro Sepiolite Deposit, Madrid Neogene Basin (Spain)

Chemistry of Mg Smectites in Lacustrine Sediments from the Vicalvaro Sepiolite Deposit, Madrid Neogene Basin (Spain)

Sediment geochemistry, mineral precipitation and clay neoformation on the Mkuze River floodplain, South Africa

Diagenetic transformation of dolomite into stevensite in lacustrine sediments from Jbel Rhassoul, Morocco

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