Clay Minerals Associated with the Precambrian Gowganda Formation of Ontario

Clay Minerals ◽  
1970 ◽  
Vol 8 (4) ◽  
pp. 471-477 ◽  
Author(s):  
R. W. Tank ◽  
L. McNeely
Keyword(s):  
Clay Minerals ◽  
Mixed Layer ◽  
Low Grade ◽  
High Grade ◽  
X Ray ◽  
Grade Metamorphism ◽  
Layer Material

AbstractX-ray analyses indicate that chlorite, illite and mixed-layer chloritesmectite are present in the < 2μ fraction of the Precambrian Gowganda Formation near Bruce Mines, Ontario. The mixed-layer material is restricted to the porous graywacke sandstones and is epigenetic in origin. The chlorite and illite are ubiquitous and may reflect high-grade diagenesis, low-grade metamorphism or a source rich in these minerals.

Mixed-layer mica-chlorite in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain)

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 307-324 ◽  
Author(s):  
M. D. Ruiz Cruz
Keyword(s):  
Electron Microscopy ◽  
Mixed Layer ◽  
Analytical Electron Microscopy ◽  
Low Grade ◽  
X Ray ◽  
Betic Cordilleras ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Microscopy Data ◽  
Ray Patterns

AbstractMixed-layered phyllosilicates with composition intermediate between mica and chlorite were identified in very low-grade metaclastites from the Malàguide Complex (Betic Cordilleras, Spain), and studied by X-ray diffraction, and transmission and analytical electron microscopy. They occur both as small grains in the rock matrix, and associated with muscovitechlorite stacks. Transmission electron microscope observations revealed a transition from chlorite to ordered 1:1 interstratifications through complex 1:2 and 1:3 interstratifications. Analytical electron microscopy data indicate a composition slightly different from the sum of discrete trioctahedral chlorite and dioctahedral mica. The types of layer transitions suggest that mixed-layer formation included two main processes: (1) the replacement of a brucite sheet by a cation sheet in the chlorite structure; and (2) the precipitation of mica-like layers between the chlorite layers. The strongest diffraction lines in oriented X-ray patterns are: 12.60 Å (002), 7.98 Å (003), 4.82 Å (005) and 3.48 Å (007).

scholarly journals Clay diagenesis and low-grade metamorphism of Tithonian and Berriasian sediments in the Cameros Basin (Spain)

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 325-333 ◽  
Author(s):  
J. F. Barrenechea ◽  
M. Rodas ◽  
M. Frey ◽  
J. Alonso-Azcárate ◽  
J. R. Mas
Keyword(s):  
Clay Mineral ◽  
Mixed Layer ◽  
Sedimentary Facies ◽  
Metamorphic Grade ◽  
Metamorphic Event ◽  
Low Grade ◽  
Grade Metamorphism ◽  
Mineral Assemblages ◽  
Cameros Basin ◽  
Southern Border

AbstractThe clay mineral assemblages of the Tithonian and Berriasian sediments (Tera and Oncala Groups) in the eastern part of the Cameros basin are investigated at seven localities. The lowest-grade assemblage, located on the southern border of the basin, contains calcite + quartz + hematite + kaolinite + mixed-layer illite-smectite (R = 1, 65 85% illite layers) + discrete illite (IC = 0.5 0.65Δ°2θ). Systematic increases in the illite and chlorite crystallinities suggest increasing metamorphic grade from the northwest part of the basin to the southeast. This trend does not follow the pattern previously described for the overlying late Berriasian–early Aptian sediments (Urbión and Enciso Groups), which exhibit a higher metamorphic grade. This may result from local variations in sedimentary facies, as well as the circulation of hot migratory fluids. Tertiary compression occurring long after the main metamorphic event is considered to be responsible for the enhanced illite and chlorite crystallinities measured in the SE extreme of the basin.

Chlorite-mica stacks in low-strain rocks from central Wales

1982 ◽  
Vol 119 (3) ◽  
pp. 243-256 ◽  
Author(s):  
J. Craig ◽  
W. R. Fitches ◽  
A. J. Maltman
Keyword(s):  
New Jersey ◽  
Clay Minerals ◽  
White Mica ◽  
West Germany ◽  
Low Grade ◽  
Controlled Growth ◽  
Common Occurrence ◽  
Grade Metamorphism ◽  
Lower Palaeozoic

SummaryWeakly deformed, low grade, Lower Palaeozoic metasediments from central Wales contain abundant stack-like intergrowths of chlorite and white mica that closely resemble stacks described from the Devonian Hunsruckschiefer of West Germany; the Ordovician Martinsburg Slate, New Jersey, U.S.A.; and elsewhere. Several theories have been proposed to explain the origin of such stacks, including a detrital origin; strain-controlled growth of chlorite on a detrital mica nucleus; and strain-controlled intergrowth during metamorphism. None of these satisfactorily explains the central Wales stacks. A detrital origin is precluded by the presence of many stacks with shapes too delicate to have survived transportation, and a lack of hydrodynamic equivalence between the stacks and the clastic host grains. Features inconsistent with strain-controlled growth are constant alignment parallel to bedding but non-systematic orientation with respect to tectonic cleavage, their common occurrence in undeformed rocks, and petrographic evidence that they precede the tectonic cleavage. It is proposed that the stacks formed during diagenesis and low-grade metamorphism, and before the onset of deformation, through mimetic growth on a primary bedding fabric composed of clay minerals.

scholarly journals Clay minerals in sediments from contact zones with basalt sills

2019 ◽  
pp. 234-247
Author(s):  
V. B. Kurnosov ◽  
B. A. Sakharov ◽  
A. R. Geptner ◽  
Yu. I. Konovalov ◽  
E. O. Goncharov
Keyword(s):  
Phase Composition ◽  
Clay Minerals ◽  
Mixed Layer ◽  
Gulf Of California ◽  
Layered Silicates ◽  
Total Thickness ◽  
Upper Pleistocene ◽  
X Ray ◽  
Diffraction Patterns ◽  
Trioctahedral Smectite

Clay minerals (fraction <0.001 mm) of Upper Pleistocene clayey-sandy-silty sediments recovered by DSDP Holes 481 and 481A in the Northern Trough, Guaymas Basin, Gulf of California, were studied by X-ray based on the modeling of diffraction patterns and their comparison with experimental diffractograms. Terrigenous clay minerals are represented mainly by dioctahedral micaceous varieties (mixed-layer disordered illite-smectites, illite) with the chlorite admixture and by kaolinite in the upper section of unaltered sediments. Intrusion of hot basalt sills (total thickness of the complex is about 27 m) provoked alterations in the phase composition of clay minerals in sediments (7.5 m thick) overlying the sill complex. These sediments include newly formed triooctahedral layered silicates (mixed-layer chlorite-smectites, smectite). Sediments inside the sill complex include trioctahedral mixed-layer mica-smtctite-vermiculite or trioctahedral smectite. The trioctahedral mixed-layer chlorite-smectite coexisting with smectite was found in a single sample of the same complex.

Strain localization mechanism of graphitic carbon-bearing rocks: Constraints from microstructure, texture and graphite geothermometry

2021 ◽  
Author(s):  
Meixia Lyu ◽  
Shuyun Cao
Keyword(s):  
Shear Zone ◽  
Strain Localization ◽  
Carbonaceous Material ◽  
Shear Zones ◽  
Graphitic Carbon ◽  
Maximum Temperature ◽  
Low Grade ◽  
High Grade ◽  
Grade Metamorphism ◽  
Average Temperature

&lt;p&gt;&lt;strong&gt;Abstracts:&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Graphitic carbon-bearing rocks can occur in low- to high-grade metamorphic units. In low-grade matamorphic rocks, graphitic carbon is often associated with brittle fault gouge whereas in middle- to high-grade metamorphic rocks, graphitic carbon commonly occurs in marble, schist or paragneiss. Previous studies showed that carbonaceous material gradually ordered from the amorphous stage, e.g. graphitization, is mainly controlled by increasing thermal metamorphism and has a good correlation with the metamorphic temperature. Besides, this ordered process is irreversible and the resulting structure is not affected by late metamorphism. Subsequently, the degree of graphitization is believed to be a reliable indicator of peak temperature conditions in the metamorphic rock. In this contribution, based on detailed field observations, the variably deformed and metamorphosed graphitic gneisses to phyllites, located within the footwall and hanging-walls unit of the Cenozoic Ailaoshan-Red River strike-slip shear zone are studied. According to lithological features and temperature determined by Raman spectra of carbonaceous material, these graphitic rocks and deformation fabrics are divided into three types. Type I is represented by medium&amp;#8211;grade metamorphism and strongly deformed rocks with an average temperature of 509 &amp;#176;C and a maximum temperature of 604 &amp;#176;C. Type II is affected by low-grade metamorphism and deformed rocks with an average temperature of 420 &amp;#176;C. Type III is affected by lower&amp;#8211;grade metamorphism and occurs in weakly deformed/undeformed rocks with an average temperature of 350 &amp;#176;C. Slip&amp;#8211;localized micro&amp;#8211;shear zone and laterally continuous or discontinuous slip planes constituted by graphitic carbon aggregates are developed in Types I and II. The electron back&amp;#8211;scattered diffraction (EBSD) lattice preferred orientation (LPO) patterns of graphitic carbon grains were firstly observed in comparison with LPO patterns of quartz and switch from basal &lt;a&gt;, rhomb &lt;a&gt; to prism &lt;a&gt; slip systems, which indicate increasing deformation temperatures. According to the graphitic slip&amp;#8211;planes, micro&amp;#8211;shear zones and mylonitic foliation constituted by graphitic carbon minerals, we also propose that the development of fine&amp;#8211;grained amorphous carbon plays an important role in rheological weakening of the whole rock during progressive ductile shearing.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Key Words:&lt;/strong&gt; graphitic carbon, strain localization, graphitic thermometry, slip&amp;#8211;localized micro&amp;#8211;shear zone, rheological weakening&lt;/p&gt;

Weathering of glauconites: reversal of the glauconitization process in a soil profile in western France

Clay Minerals ◽  
1981 ◽  
Vol 16 (3) ◽  
pp. 231-243 ◽  
Author(s):  
C. Courbe ◽  
B. Velde ◽  
A. Meunier
Keyword(s):  
Aqueous Solution ◽  
Clay Minerals ◽  
Mixed Layer ◽  
Electron Microprobe ◽  
Soil Profile ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polarizing Microscope

AbstractPolarizing microscope, electron microprobe and X-ray diffraction examination of minerals in a soil profile developed on a glauconite sand indicate that destabilization of glauconite can be a progressive process which appears to be the reverse of glauconitization. Glauconite in these soils appears to be destabilized into a mixed-layer glauconite-nontronite phase, which crystallizes as a plasma mineral. This material in turn is transformed into smectite+kaolinite+oxides. Loss of K and Fe is evident in whole rock as well as microprobe analyses of the samples. Thus glauconite can lose both Fe and K to aqueous solution during weathering, leaving aluminous clay minerals in the soil.

Clay Mineralogy of Selected Clays from the English Wealden

1962 ◽  
Vol 99 (2) ◽  
pp. 128-136 ◽  
Author(s):  
R. W. Tank
Keyword(s):  
Clay Minerals ◽  
Mixed Layer ◽  
Mineral Assemblage ◽  
Depositional Environment ◽  
Clay Mineralogy ◽  
Source Area ◽  
Parent Material ◽  
X Ray ◽  
Layer Structures ◽  
Clay Mineral Assemblage

AbstractX-ray analyses of selected samples from the argillaceous subdivisions of the English Wealden indicate that illite, kaolinite, and mixed-layer structures are present in variable amounts. The clay mineral assemblage is thought to reflect parent material, weathering conditions in the source area, and possibly some degrading of the illite structure by the action of active waters in the depositional environment. The specific clay minerals are tentatively correlated with the palaeogeographical framework proposed by Allen (1954). It is suggested that the kaolinite was derived mainly from the Palaeozoic uplands, and the bulk of the illite and mixed-layer structures from the marginal Jurassic lowland.

Mineralogy of clay marker seams in some Saskatchewan potash mines

1982 ◽  
Vol 19 (11) ◽  
pp. 2126-2140 ◽  
Author(s):  
D. J. Mossman ◽  
R. N. Delabio ◽  
D. Mackintosh
Keyword(s):  
Clay Minerals ◽  
Mixed Layer ◽  
Potassium Feldspar ◽  
Direct Products ◽  
Red Beds ◽  
X Ray ◽  
Insoluble Material ◽  
Heat Treated ◽  
Central Canada ◽  
Approximate Order

Water-insoluble material is present mainly as thin stratigraphic layers throughout the potash ore zone(s) of the Prairie Evaporite. These clay seams constitute about 6% of the ore as mined. After clay minerals, which make up about one third of the total, the main water-insoluble constituents, in approximate order of decreasing abundance, are anhydrite, dolomite, hematite, quartz, potassium feldspar, hydrocarbon, and sporadic non-diagnostic palynomorphs.Clay mineralogy in the following mines has been studied: Cominco (Vanscoy); Central Canada Potash Co. Ltd. (Colonsay); and Potash Corporation of Saskatchewan (Allan and Lanigan). A total of 49 samples has been examined. In each sample, following concentration of clay minerals by centrifuging, X-ray diffractograms were obtained for untreated, glycolated, and heat-treated material (300, 450, 580, 650, and 725 °C). Additional runs were made on several samples under conditions of controlled humidity.The main clay minerals are Fe–Mg chlorite (14 Å (1.4 nm)), illite, and Mg-septechlorite (7 Å (0.7 nm)). Of the two chlorites, septechlorite is the more thermally stable. One or more of sepiolite, smectite, mixed layer (chlorite–smectite), and possibly traces of vermiculite are also present in some samples. The septechlorite, sepiolite, and vermiculite very likely originated as direct products of evaporation under hypersaline conditions, or are the result of diagenesis. Absence of otherwise ubiquitous septechlorite in a sample from Second Red Beds west of the 0-edge of the evaporite basin supports this concept. The proportions and kinds of clay minerals present in the ore zone(s) seem to reflect the extent to which hypersaline conditions were developed. The illite and 14 Å (1.4 nm) chlorite are of regional (detrital) origin.

scholarly journals Clay Mineralogy of some Lower Tertiary (Paleogene) Sediments from Denmark

1963 ◽  
Vol 4 (9) ◽  
pp. 1-45
Author(s):  
R. W Tank
Keyword(s):  
Clay Minerals ◽  
Mixed Layer ◽  
Physical Environment ◽  
Amorphous Material ◽  
Clay Mineralogy ◽  
Source Area ◽  
Lower Eocene ◽  
X Ray ◽  
Volcanic Material ◽  
Zone Ii

108 samples from the Paleogene rocks of Denrnark were examined by standard X-ray techniques and their clay suites form the basis of the present study. The X-ray data have permitted a three-fold mineralogical zonation of the Danish Paleogene.The oldest zone (Zone I) is characterized by a high montmorillonite content, minor or trace amounts of illite and segregated mixed-layer clay minerals and the absence of kaolinite. The boundaries of Zone I coincide with the Paleocene Series. The clay minerals are detrital and are derived from a carbonate terrain bordering the Fennoscandian massif. Diagenetic changes in the marine environment and segregation by sorting and floculation are important factors accounting for the high montmorillonite content.A middle zone (Zone Il) is characterized by the predominance of amorphous material. Minor amounts of montmorillonite, illite and kaolinite are present and represent alteration produets of volcanic ash. Zone II is restricted to the Mo Clay Formation.The youngest zone (Zone III) contains variable amounts of montmorillonite, illite, kaolinite and random mixed-layer montmorillonite-illite. The boundaries of Zone III appear to extend from the lower Eocene to the Miocene. The clay minerals of Zone III are products of the alteration of the volcanic material of the Fennoscandian massif. Changes in the conditions of the source area and the physical environment of deposition account for the mineralogical variations.

Sign in / Sign up

Export Citation Format

Share Document