Illite from the Potsdam Sandstone of New York: A Probable Noncentrosymmetric Mica Structure

Reynolds, Robert C.; Thomson, C. H.

doi:10.1346/ccmn.1993.0410107

Cited by 33 publications

(19 citation statements)

References 21 publications

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“…For illite, the most common polytypes are the 1 M d , 1M and 2M 1 (e.g. Reynolds and Thomson 1993). With raising temperature, illite shows irreversible polytype transformation of 1 M d ?…”

Section: Mineralogy and K-ar Dating Of Fault Gougesmentioning

confidence: 99%

Exhumation and uplift of the Sierras Pampeanas: preliminary implications from K–Ar fault gouge dating and low-T thermochronology in the Sierra de Comechingones (Argentina)

Löbens

Bense

Wemmer

et al. 2010

Int J Earth Sci (Geol Rundsch)

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The Sierras Pampeanas in central and northwestern Argentina constitute a distinct morphotectonic feature between 27°S and 33°S. The last stage of uplift and deformation in this area are interpreted to be closely related to the Andean flat-slab subduction of the Nazca plate beneath the South American plate. K-Ar fault gouge dating and low-temperature thermochronology along two transects within the Sierra de Comechingones reveal a minimum age for the onset of brittle deformation about 340 Ma, very low exhumation rates since Late Paleozoic time, as well as a total exhumation of about 2.3 km since the Late Cretaceous. New Ar-Ar ages (7.54-1.91 Ma) of volcanic rocks from the San Luis volcanic belt support the eastward propagation of the flat-slab magmatic front, confirming the onset of flat-slab related deformation in this region at 11.2 Ma. Although low-temperature thermochronology does not clearly constrain the signal of the Andean uplift, it is understood that the current structural relief related to the Comechingones range has been achieved after the exhumation of both fault walls (circa 80-70 Ma).

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“…For illite, the most common polytypes are the 1 M d , 1M and 2M 1 (e.g. Reynolds and Thomson 1993). With raising temperature, illite shows irreversible polytype transformation of 1 M d ?…”

Section: Mineralogy and K-ar Dating Of Fault Gougesmentioning

confidence: 99%

Exhumation and uplift of the Sierras Pampeanas: preliminary implications from K–Ar fault gouge dating and low-T thermochronology in the Sierra de Comechingones (Argentina)

Löbens

Bense

Wemmer

et al. 2010

Int J Earth Sci (Geol Rundsch)

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“…Drits et al (1993) noted that the 3T and cv-lM structures produce similar diffraction effects. However, Reynolds and Thomson (1993) found that in determining the structure of the Potsdam illite, the d values of the Potsdam illite could not be reconciled with a hexagonal structure (e.g., 337) and these values are (1984). Indexing was possible because the Potsdam illite has sharp diffraction maxima.…”

Section: Introductionmentioning

confidence: 98%

“…Oblique-texture electron diffraction (OTED) work by Tsipursky and Drits (1984) showed that dioctahedral smectites have a wide range of proportions of cv and tv layers. Reynolds and Thomson (1993) showed that the illite from the Potsdam sandstone of New York has the cv structure and Drits et al (1993) described another occurrence. Reynolds (1992), McCarty (1993), McCarty and Reynolds (1995), and Drits et al (1998) demonstrated that cv structures exist in I-S exhibiting the 1M and 1Md stacking sequences, and that cv 2:1 layers are commonly interstratified with tv layers.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 1 shows a comparison between random powder X-ray diffraction patterns for the cv Potsdam illite-lM (Reynolds and Thomson, 1993) and a tv 1M hydrothermal illite from Silverton Caldera, Colorado (Ebed et al, 1987). The differences in their diffraction patterns between 20 = 20-35 ~ are evident, which demonstrates that these two structures can be confidently identified.…”

Section: Introductionmentioning

confidence: 99%

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Three-Dimensional Crystal Structures of Illite-Smectite Minerals in Paleozoic K-Bentonites from the Appalachian Basin

McCarty¹,

Reynolds

2001

Clays and clay miner.

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Abstract--The three-dimensional crystal structures of illite-smectite (I-S) in K-bentonite samples from the Appalachian Basin are characterized by rotational disorder in the stacking sequence of 2:1 illite layers, different proportions of n60 ~ rotations (as opposed to n120 ~ in the rotated layers, and layers with centrosymmetric trans-vacant (tv) octahedral sites that are randomly interstratified with noncentric cis-vacant (cv) layers. The proportion of cv interstratification in the I-S increases with tetrahedral A1 and decreases with octahedral Mg and Fe content. The I-S minerals in the northern Appalachian basin K-bentonites are characterized by high (79% average) proportions of cv (Pcv) layers. In contrast, I-S from equivalent Kbentonites from the southern Appalachian basin has low Pcv values (38% average). These values do not correlate with expandability or rotational disorder. The geographic distribution of these I-S structural parameters may have resulted from possibly short-term, hot, and advective fluid migrations that differed in Mg concentrations and/or other physical and chemical parameters.

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“…Drits et al (1984a) formulated structural and diffraction criteria to distinguish between dioctahedral 1M micas consisting of cis-vacant (cv 1M) or trans-vacant (tv 1M) 2:1 layers. Based on these criteria, cv 1M illites were found in different geological environments (Zvyagin et al, 1985;Drits et al, 1993a;Reynolds & Thompson, 1993). Conversely, Sakharov et al, (1990) andDrits et al (1993b) studied a large collection of glauconites differing in chemical composition, age, location and structural perfection.…”

mentioning

confidence: 99%

Isomorphous cation distribution in celadonites, glauconites and Fe-illites determined by infrared, Mössbauer and EXAFS spectroscopies

et al. 1997

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AB S TRACT: Celadonite, glauconite and Fe-illite samples were studied by XRD, EXAFS, IR and M6ssbauer spectroscopy. The samples were monomineralic and corresponded to IM polytype. In the OH-stretching region of the IR spectra the content of each definite pair of cations bonded to OH groups was determined. The number of heavy (Fe) and light (AI, Mg) octahedral cations nearest to Fe was found by the EXAFS technique. The predicted quadrupole splitting values for each definite arrangement of cations nearest to Fe 3+ were used to interpret the M6ssbauer spectra. After the fitting procedure, the intensity of each doublet corresponded to a definite set of local cation arrangements around Fe 3+ and to a definite occurrence probability of these arrangements. Computer simulation and the experimental data obtained were used to reconstruct the distribution of isomorphous octahedral cations in the 2:1 layers. For all samples, R 2+ cations prefer to occupy one of the two symmetrically independent cis-sites and RZ+-R 2+ and/or AI-Fe 3+ were prohibited in the directions forming _+ 120 ~ with the b axis. Therefore, octahedral sheets of the samples revealed domain structure, in which domains differ in size, in the nature of predominant cation and/or by cation ordering.One of the characteristic features of phyllosilicates and, in particular, dioctahedral micas, is a wide variation of chemical compositions. Different samples of the same mineral may differ not only in octahedral and tetrahedral cation contents of 2:1 layers, but also in their long-and short-range ordering in isomorphous cation distribution. Determination of the actual cation distribution in dioctahedral micas is a complex problem. X-ray diffraction (XRD) yields data only on the averaged composition of cations in the unit-cell sites, ignoring a possible short-range ordering. For finely dispersed minerals containing stacking faults, even this information is often difficult to obtain.Spectroscopic methods are, therefore, especially useful, since they probe local atomic environments and have a potential to determine short-range cation ordering. Utilization of spectroscopic methods, however, often meets certain difficulties. One of the main problems is that most of these methods are indirect, that is, they provide indirect structural information about a sample under study. For this reason, interpretation of spectroscopic data is not always feasible or properly based.One of the effective ways to determine the actual cation distribution consists of the application of complex diffraction and spectroscopic methods to the same sample. Obviously, the greater the number of methods involved, the more comprehensive the structural information obtained. Each method, however, has its own advantages and limitations and therefore provides only a partial solution to a 9 1997 The Mineralogical Society 154 K A. Drits et al.general problem of cation order/disorder in dioctahedral mica structures. Therefore, even if unambiguous interpretation of experimental data is provided, the actual ca...

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Illite from the Potsdam Sandstone of New York: A Probable Noncentrosymmetric Mica Structure

Cited by 33 publications

References 21 publications

Exhumation and uplift of the Sierras Pampeanas: preliminary implications from K–Ar fault gouge dating and low-T thermochronology in the Sierra de Comechingones (Argentina)

Exhumation and uplift of the Sierras Pampeanas: preliminary implications from K–Ar fault gouge dating and low-T thermochronology in the Sierra de Comechingones (Argentina)

Three-Dimensional Crystal Structures of Illite-Smectite Minerals in Paleozoic K-Bentonites from the Appalachian Basin

Isomorphous cation distribution in celadonites, glauconites and Fe-illites determined by infrared, Mössbauer and EXAFS spectroscopies

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