Characteristics of a Mg-palygorskite in Miocene rocks, Madrid Basin (Spain)

Romero, Emilia García; Suárez, M.; Revuelta, María Ángeles Bustillo

doi:10.1346/ccmn.2004.0520409

Cited by 63 publications

(4 citation statements)

References 30 publications

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“…The identification of Pal bands before modification was carried out by analogy with other studies conducted previously on similar types of fibrous clay minerals (Blanco et al , 1989; Chahi et al ., 2002; Garcia-Romero et al , 2004; Suarez et al , 2006).…”

Section: Resultsmentioning

confidence: 99%

Effects of clay activation and amine chain length on silica–palygorskite heterostructure properties

2023

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Section: Resultsmentioning

confidence: 99%

Effects of clay activation and amine chain length on silica–palygorskite heterostructure properties

2023

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“…Higher MgO/SiO 2 ratios may reflect a degree of Mg substitution in Al sites as well as an intergrowth of sepiolite (García‐Romero & Suárez, 2010; Suárez & García‐Romero, 2013). A Fe 2 O 3 content of up to ~4 wt% is common within palygorskite, which may be substituted for Al as well as adsorbed onto clay surfaces (del Buey et al, 2018; García‐Romero et al, 2004; García‐Romero & Suárez, 2010; Middea et al, 2013).…”

Section: Resultsmentioning

confidence: 99%

Microbial influence on dolomite and authigenic clay mineralisation in dolocrete profiles of NW Australia

et al. 2023

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Dolomite (CaMg(CO3)2) precipitation is kinetically inhibited at surface temperatures and pressures. Experimental studies have demonstrated that microbial extracellular polymeric substances (EPS) as well as certain clay minerals may catalyse dolomite precipitation. However, the combined association of EPS with clay minerals and dolomite and their occurrence in the natural environment are not well documented. We investigated the mineral and textural associations within groundwater dolocrete profiles from arid northwest Australia. Microbial EPS is a site of nucleation for both dolomite and authigenic clay minerals in this Late Miocene to Pliocene dolocrete. Dolomite crystals are commonly encased in EPS alveolar structures, which have been mineralised by various clay minerals, including montmorillonite, trioctahedral smectite and palygorskite‐sepiolite. Observations of microbial microstructures and their association with minerals resemble textures documented in various lacustrine and marine microbialites, indicating that similar mineralisation processes may have occurred to form these dolocretes. EPS may attract and bind cations that concentrate to form the initial particles for mineral nucleation. The dolomite developed as nanocrystals, likely via a disordered precursor, which coalesced to form larger micritic crystal aggregates and rhombic crystals. Spheroidal dolomite textures, commonly with hollow cores, are also present and may reflect the mineralisation of a biofilm surrounding coccoid bacterial cells. Dolomite formation within an Mg‐clay matrix is also observed, more commonly within a shallow pedogenic horizon. The ability of the negatively charged surfaces of clay and EPS to bind and dewater Mg2+, as well as the slow diffusion of ions through a viscous clay or EPS matrix, may promote the incorporation of Mg2+ into the mineral and overcome the kinetic effects to allow disordered dolomite nucleation and its later growth. The results of this study show that the precipitation of clay and carbonate minerals in alkaline environments may be closely associated and can develop from the same initial amorphous Ca–Mg–Si‐rich matrix within EPS. The abundance of EPS preserved within the profiles is evidence of past microbial activity. Local fluctuations in chemistry, such as small increases in alkalinity, associated with the degradation of EPS or microbial activity, were likely important for both clay and dolomite formation. Groundwater environments may be important and hitherto understudied settings for microbially influenced mineralisation and for low‐temperature dolomite precipitation.

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“…Palygorskite, also known as attapulgite, is a hydrated clay mineral of magnesium and aluminum with microfibrous morphology and low surface charges [28]. The structure of attapulgite is of 2:1 type with two tetrahedral sheets of silicon oxides joined by a central octahedral sheet of magnesium and aluminum oxides [29]. The diffractogram of fresh palygorskite (Fig.…”

Section: X-ray Diffraction Resultsmentioning

confidence: 99%