Novel properties of intercalated layered solids: from graphite to sheet silicates

AbstractThe structure hierarchy hypothesis states that structures may be ordered hierarchically according to the polymerisation of coordination polyhedra of higher bond-valence. A hierarchical structural classification is developed for sheet-silicate minerals based on the connectedness of the two-dimensional polymerisations of (TO4) tetrahedra, where T = Si4+ plus As5+, Al3+, Fe3+, B3+, Be2+, Zn2+ and Mg2+. Two-dimensional nets and oikodoméic operations are used to generate the silicate (sensu lato) structural units of single-layer, double-layer and higher-layer sheet-silicate minerals, and the interstitial complexes (cation identity, coordination number and ligancy, and the types and amounts of interstitial (H2O) groups) are recorded. Key aspects of the silicate structural unit include: (1) the type of plane net on which the sheet (or parent sheet) is based; (2) the u (up) and d (down) directions of the constituent tetrahedra relative to the plane of the sheet; (3) the planar or folded nature of the sheet; (4) the layer multiplicity of the sheet (single, double or higher); and (5) the details of the oikodoméic operations for multiple-layer sheets. Simple 3-connected plane nets (such as 63, 4.82 and 4.6.12) have the stoichiometry (T2O5)n (Si:O = 1:2.5) and are the basis of most of the common rock-forming sheet-silicate minerals as well as many less-common species. Oikodoméic operations, e.g. insertion of 2- or 4-connected vertices into 3-connected plane nets, formation of double-layer sheet-structures by (topological) reflection or rotation operations, affect the connectedness of the resulting sheets and lead to both positive and negative deviations from Si:O = 1:2.5 stoichiometry. Following description of the structural units in all sheet-silicate minerals, the minerals are arranged into decreasing Si:O ratio from 3.0 to 2.0, an arrangement that reflects their increasing structural connectivity. Considering the silicate component of minerals, the range of composition of the sheet silicates completely overlaps the compositional ranges of framework silicates and most of the chain-ribbon-tube silicates.

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Laser probe 40Ar/39Ar and conventional K/Ar dating of illites associated with the McClean unconformity-related uranium deposits, north Saskatchewan, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e87-002 ◽

1987 ◽

Vol 24 (1) ◽

pp. 10-23 ◽

Cited By ~ 17

Author(s):

C. J. Bray ◽

E. T. C. Spooner ◽

C. M. Hall ◽

D. York ◽

T. M. Bills ◽

...

Keyword(s):

Hydrothermal Alteration ◽

Uranium Mineralization ◽

Complete Agreement ◽

Time Interval ◽

Uranium Deposits ◽

Class Interval ◽

Laser Probe ◽

Alteration Halo ◽

Sheet Silicates ◽

Sedimentary Layer

The McClean group of uranium deposits consists of elongate pods of high-grade uranium mineralization (width = ~ 15–40 m) tightly confined to within ±40 m of the basal unconformity. Uraninite–coffinite–sulphide/arsenide–chlorite–siderite mineralization at McClean is surrounded by a muscovite/illite ± haematite hydrothermal alteration halo,which can contain coffinite–pararammelsbergite (NiAs2) – muscovite/illite nodules. Ten laser probe 40Ar/39Ar dates, two of which are step-heat runs showing good plateaus, and 10 conventional K – Ar dates for this material show a distribution with asharp beginning at ~ 1320 Ma, a marked peak in the 1250–1200 Ma class interval, and a tail to dates as young as 1002 ± 33 (1σ) Ma. These determinations are in complete agreement with direct (U–Pb and Sm–Nd) dates on uraninite at the Midwest (e.g., 1328 ± 9 and 1110 ± 28 Ma), Key Lake (e.g., 1350 ± 4 and 1281 ± 6 Ma), and Collins Bay B deposits(e.g., 1281 ± 80 Ma). Since estimated depositional ages for the Athabasca sedimentary sequence are in the 1470 ± 15 to1428 ± 15 Ma range, uranium mineralization and associated hydrothermal alteration started ~ 100–150 Ma after Athabasca sedimentation, a result consistent with fluid-inclusion data, which indicate that mineralization took place at ~ 160–220 °C beneath ~ 3000 m of cover at a relatively advanced stage in the evolution of the basin. It is suggested that the similar initiation dates for uranium mineralization might reflect a widespread faulting event that affected the eastern part of the basin. A muscovite/illite closure temperature calculated from a measured argon diffusion activation energy of 36 ± 4 kcal/mol(1 kcal = 4.1868 kJ) indicates that the base of the Athabasca Basin in the McClean area has not been disturbed by temperatures greater than ~ 140 °C for 1.1–1.0 Ga. It is suggested that mineralization ceased when fracture permeability had been sealed by crystallization of secondary minerals. The duration of mineralization may have been ~ 150 Ma, a relatively long time interval not unreasonable for the base of a sedimentary basin.Secondary illites interstitial to quartz grains from the HLM1 stratigraphic borehole give 40Ar/39Ar ages of 1459 ± 4, 1341 ± 4, and 1113 ± 11 Ma, indicating that formation of diagenetic sheet silicates predated uranium mineralization. Recrystallization or formation of sheet silicates in relict sedimentary layers and in subunconformity altered basement referred to as "regolith" started at approximately the same time, since dates of 1484 ± 55 Ma (sedimentary layer), 1482 ± 49 Ma (regolith), and 1453 ± 49 Ma (regolith) have been obtained. Resetting of interstitial, sedimentary layer, and regolith sheet-silicate dates continued to ages of, for example, 1113 ± 11 Ma (interstitial) and 1038 ± 55 Ma (sedimentary layer), which exactly coincide with the youngest ages obtained for the alteration halo associated with mineralization.The youngest date obtained is a 40Ar/39Ar plateau age of 673 ± 3 Ma. The sample (2045-517) was obtained from within 2 mm of a concentrated pitchblende nodule and may have been disturbed in some way by its proximity to uranium.

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Serpentine and chlorite as effective Ni-Cu sinks during weathering of the Aguablanca sulphide deposit (SW Spain). TEM evidence for metal-retention mechanisms in sheet silicates

European Journal of Mineralogy ◽

10.1127/0935-1221/2011/0023-2084 ◽

2011 ◽

Vol 23 (2) ◽

pp. 179-196 ◽

Cited By ~ 12

Author(s):

Saioa Suárez ◽

Fernando Nieto ◽

Francisco Velasco ◽

Francisco J. Martín

Keyword(s):

Sulphide Deposit ◽

Retention Mechanisms ◽

Metal Retention ◽

Sw Spain ◽

Sheet Silicates

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What steers deformation within fold-and-thrust belts: insights from the carbonate multilayer footwall of the Belluno Thrust, Italian eastern Southern Alps

10.5194/egusphere-egu21-1068 ◽

2021 ◽

Author(s):

Costantino Zuccari ◽

Giulio Viola ◽

Gianluca Vignaroli ◽

Luca Aldega

Keyword(s):

Large Scale ◽

Southern Alps ◽

Strain Localisation ◽

Geometric Framework ◽

Thrust Belts ◽

Cumulative Strain ◽

Fold And Thrust Belts ◽

Sheet Silicates ◽

Slip Planes ◽

Multiple Deformation

<p>Despite significant recent progress in the understanding and quantification of the parameters controlling deformation modes in carbonate multilayers within fold-and-thrust belts, the details of early deformation and faulting during the initial stages of large-scale thrusting remain poorly documented and understood. Aiming to narrow this knowledge gap, we have chosen to study the relatively low-strain carbonate multilayer footwall of the Belluno Thrust (BT), one of the most external and S-vergent thrusts of the eastern Southern Alps (Italy). The BT footwall is composed of a c. 600 m thick Meso-Cenozoic multilayer succession of shallow water carbonate and pelagic sedimentary units characterized by strong mineralogical heterogeneity, with calcite (32-98%), sheet silicates (1-27%), and quartz (1-37%) as principal components. Its structural framework reflects cumulative strain due to multiple deformation events and is defined by the superposition of different structures such as i) south-verging asymmetric folds, ii) faulted folds, cut by slip planes with centimetric to metric throw, iii) SC-C&#8217; fabrics in the marly layers, and iv) cataclastic domains. &#160;Structures recording the early shortening increments are generally well preserved mesoscopic upright folds. Asymmetric folds with gently N-dipping backlimbs and steeply S-dipping (or even overturned N-dipping) forelimbs, record further shortening of the early upright and symmetrical folds. Strain is strongly partitioned within the marly layers, with discrete faults commonly defined by multiple slip surfaces forming duplex geometries and SC-C&#8217; fabrics and exploiting millimetric to centimetric marly beds as detachment layers. Thrusts and diffuse reverse faults not associated with any cataclasite localise along the backlimbs of the asymmetric folds, suggesting dominant layer-parallel shortening. Cataclasites develop instead along the thrust surfaces that cut across the steeply dipping (locally even overturned) forelimbs, where cataclastic flow becomes the dominant deformation mechanism. On the vertical forelimbs, cataclasis and strain localisation are commonly associated with veins, which contributed to harden the rock system. &#160;</p><p>Based on our systematic observations, we propose that deformation progressively evolved from folding and layer-parallel shortening (initial phases) to faulting and cataclasis (final phases) as a function of the dynamic interplay of the following factors: i) the geometrical relationships between fault orientation, fold attitude (forelimb and backlimb domains) and stress field, ii) the lithotype, which we conveniently account for by referring to the ratio between the cumulative thickness of the outcrop marly layers and the total measured stratigraphic thickness, iii) the involvement of fluids during deformation, iv) the mineral assemblage of the involved layers and v) the geometric framework of the domain localising strain with respect to the principal stress axes orientation. We conclude that these parameters play a major role in guiding strain localisation and partitioning during continuous shortening within fold-and-thrust belts. They also govern the transition from overall aseismic creep to coseismic rupturing at the scale of mesoscopic structures and, possibly, of the entire belt.</p>

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A structure hierarchy for silicate minerals: chain, ribbon, and tube silicates

Mineralogical Magazine ◽

10.1180/mgm.2020.13 ◽

2020 ◽

Vol 84 (2) ◽

pp. 165-244 ◽

Cited By ~ 2

Author(s):

Maxwell C. Day ◽

Frank C. Hawthorne

Keyword(s):

Repeat Unit ◽

Structural Connectivity ◽

The Other ◽

Silicate Minerals ◽

One Dimensional ◽

Compositional Range ◽

Repeat Units ◽

Sheet Silicates ◽

Sheet Silicate ◽

Connectivity Degree

AbstractA structure hierarchy is developed for chain-, ribbon- and tube-silicate based on the connectedness of one-dimensional polymerisations of (TO4)n− tetrahedra, where T = Si4+ plus P5+, V5+, As5+, Al3+, Fe3+, B3+, Be2+, Zn2+ and Mg2+. Such polymerisations are described by a geometrical repeat unit (with ng tetrahedra) and a topological repeat unit (or graph) (with nt vertices). The connectivity of the tetrahedra (vertices) in the geometrical (topological) repeat units is denoted by the expression cTr (cVr) where c is the connectivity (degree) of the tetrahedron (vertex) and r is the number of tetrahedra (vertices) of connectivity (degree) c in the repeat unit. Thus cTr = 1Tr12Tr23Tr34Tr4 (cVr = 1Vr12Vr23Vr34Vr4) represents all possible connectivities (degrees) of tetrahedra (vertices) in the geometrical (topological) repeat units of such one-dimensional polymerisations. We may generate all possible cTr (cVr) expressions for chains (graphs) with tetrahedron (vertex) connectivities (degrees) c = 1 to 4 where r = 1 to n by sequentially increasing the values of c and r, and by ranking them accordingly. The silicate (sensu lato) units of chain-, ribbon- and tube-silicate minerals are identified and associated with the relevant cTr (cVr) symbols. Following description and association with the relevant cTr (cVr) symbols of the silicate units in all chain-, ribbon- and tube-silicate minerals, the minerals are arranged into decreasing O:T ratio from 3.0 to 2.5, an arrangement that reflects their increasing structural connectivity. Considering only the silicate component, the compositional range of the chain-, ribbon- and tube-silicate minerals strongly overlaps that of the sheet-silicate minerals. Of the chain-, ribbon- and tube-silicates and sheet silicates with the same O:T ratio, some have the same cVr symbols (vertex connectivities) but the tetrahedra link to each other in different ways and are topologically different. The abundance of chain-, ribbon- and tube-silicate minerals decreases as O:T decreases from 3.0 to 2.5 whereas the abundance of sheet-silicate minerals increases from O:T = 3.0 to 2.5 and decreases again to O:T = 2.0. Some of the chain-, ribbon- and tube-silicate minerals have more than one distinct silicate unit: (1) vinogradovite, revdite, lintisite (punkaruaivite) and charoite have mixed chains, ribbons and/or tubes; (2) veblenite, yuksporite, miserite and okenite have clusters or sheets in addition to chains, ribbons and tubes. It is apparent that some chain-ribbon-tube topologies are favoured over others as of the ~450 inosilicate minerals, ~375 correspond to only four topologically unique graphs, the other ~75 minerals correspond to ~46 topologically unique graphs.

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Sheet and Tube Organosilicon Polymers

MRS Proceedings ◽

10.1557/proc-519-321 ◽

1998 ◽

Vol 519 ◽

Cited By ~ 1

Author(s):

D. E. Katsoulist ◽

T. C.-S. Chaot ◽

E. A. McQuistont ◽

Chenggang Chen ◽

Malcolm E. Kenney ◽

...

Keyword(s):

Mechanical Properties ◽

Solid State ◽

Interlayer Spacing ◽

Heterogeneous Reactions ◽

Naturally Occurring ◽

Pendent Groups ◽

Sheet Silicates ◽

Siloxane Polymers ◽

Organosilicon Polymers

AbstractReaction of chlorosilanes with sheet silicates, such as the naturally occurring apophyllite, [Ca4Si8O2O(F, OH).8H2O] results in the formation of sheet organofunctional siloxane polymers. Similarly, reaction of chlorosilanes with the tube silicate K2CuSi4O10results in the formation of tube organofunctional siloxane polymers. Representative polymers have been characterized by XRD, KR, XPS and solid state 29Si NMR. The interlayer spacing of the sheet polymers varies with the type of the group pendent on the sheet. When the organofunctional pendent groups of the sheet polymers contain reactive sites, further reactivity can be demonstrated with heterogeneous reactions such as hydrosilation. The sheet polymers behave as very effective thickeners of siloxane fluids. Dispersions of them in siloxane fluids exhibit thixotropic properties. The organosilicon polymers have the potential to show useful chemical, thermal, rheological and mechanical properties

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