The higher pressure reaction by which Mg-sursassite breaks down to form phase A is a fluid-conserving one: The temperatures over which many of these hydrous phases in the MgO–Al2O3–SiO2–H2O system are stable are sufficiently low that they could be present only in cold subducting slabs or cold subcontinental lithosphere, not in ‘ambient’ mantle. In this environment chlorite may be a retrograde metamorphic alteration mineral of existing ferromagnesian minerals, or it may be present as a metasomatism product via addition of Fe, Mg, or other compounds into the rock mass. Figures 1 and 2 show typical clay mineral suites, one from Oregon and one from Alaska, and the criteria used to identify and characterize the various clay minerals. Other 2:1 clay kinds exist along with sepiolite or attapulgite, clays with long water channels inner to their shape. X-ray diffraction patterns of some representative samples taken from hole G runs 1–3 and hole G runs 4–6. The shaded box represents plausible mantle peridotite compositions, with the upper bound being at ∼5 wt.% Al2O3. Initial testing utilized solubility analyses to determine which minerals are affected by acid. Their results (Figure 14) require a steep positive slope to the fo+en+Mg-s=prp+H2O reaction, and define the ability of Mg-sursassite to act as an intermediate water host between chlorite and phase A. Varma, in Shale Gas, 2017. Differences between Fe chlorite and Mg chlorite. Based on microstructural observations, Schleicher et al. (C–D) Samples adjacent to and within the central deformation zone (CDZ). doi:10.1130/0091-7613(2001)029<0503:CTMOOF>2.0.CO;2, Potential role of mantle-derived fluids in weakening the San Andreas fault, Implications of microstructural studies of the SAFOD gouge for the strength and deformation mechanisms in the creeping segment of the San Andreas fault, Fall Meeting supplement, abstract T41A-2100, Diagenetic mineralogy and controls on albitization and laumontite formation in Paleogene arkoses, Santa Ynez Mountains, California, American Association of Petroleum Geologists Memoir 37, Introduction to special sections: Preparing for the San Andreas Fault Observatory at Depth, Structure and composition of the San Andreas fault zone at Parkfield: Results from SAFOD Phases 1 and 2, Fall Meeting supplement, abstract T23E-05, Structure and composition of the San Andreas fault in central California: Recent results from SAFOD sample analyses, Fall Meeting supplement, abstract TT53F-01, Origin, diagenesis, and mineralogy of chlorite minerals in Devonian lacrustrine mudrocks, Orcadian Basin, Scotland, Fault rocks from the SAFOD core samples: Implications for weakening at shallow depths along the San Andreas fault, California, An experimentally derived model for smectite to illite conversion and its use as a geothermometer, Effect of hydration state on the frictional properties of montmorillonite-based fault gouge, On the relation between fault strength and frictional stability, Smectite-to-chlorite transformation in thermally metamorphosed volcanoclastic rock in the Kamikita area, northern Honshu, Japan, Conversion of trioctahedral smectite to interstratified chlorite/smectite in Pliocene acidic pyroclastic sediments of the Ohyu district, Akita Prefecture, Japan, Nanoscale porosity in SAFOD core samples (San Andreas fault), Origin and mechanical significance of foliated cataclastic rocks in the cores of crustal-scale faults: Examples from the Median Tectonic Line, Japan, The nature and importance of phyllonite development in crustal-scale fault cores: An example from the Median Tectonic Line, Japan, Occurrence of mixed-layer illite/smectite at temperature of 285 degrees C in an active hydrothermal system and its significance, Frictional sliding in serpentine at very high pressure, A technique for maintaining texture and permanent expansion of smectite interlayers for TEM observations, Results of elemental, stable isotope, organic matter and fission-track analyses of SAFOD drill-hole cuttings and core material, Fall meeting supplement, abstract T21C-0434, Synthesis of smectite clay minerals: A critical review, Alteration of basaltic rocks by hydrothermal activity at 100–300 C, The internal structure of fault zones: Fluid flow and mechanical properties, Heat flow and energetics of the San Andreas fault zone, Corrensite and chlorite-rich C-S mixed layers in sandstones from the Macigno Formation (northwestern Tuscany, Italy), Low strength of deep San Andreas fault gouge from SAFOD core, The drained residual strength of cohesive soils, Burial diagenesis of illite/smectite in shales and the origin of authigenic quartz and secondary porosity in sandstones, Moisture-related weakening and strengthening of a fault activated at seismic slip rates, Talc bearing serpentinite and the creeping section of the San Andreas fault, X-Ray Diffraction and the Identification and Analysis of Clay Minerals (2nd ed. This means it generally contributes little gamma activity and is unlikely to significantly reduce electrical resistivity. Although this difference is larger than Ulmer and Trommsdorff's estimate as illustrated in Figure 13, their point—that the stability of chlorite in peridotite will not be significantly less than the stability of chlorite in a bulk composition of its own stoichiometry—is still valid. (1999).” As of early 2000s, it appears that this phase is best described as Mg-sursassite, following the usage of Gottschalk et al. Illite origin; Glauconite; Celadonite; Smectite; Chlorite; Vermiculite; Mixed-lader clay; mineral; Attapulgite and palygorskite; Sepiolite; Kaolinite; Dickite and nacrite; Halloysite; Allophane; Trioctahedral 1;1 Clay mineral; Low ... Abbreviations as in Table 1. Calculations are on the basis of 14 oxygens for chlorite. Holdsworth et al. In their chemographic analyses of the MgO–Al2O3–SiO2–H2O system, both Ulmer and Trommsdorff (1999) and Artioli et al. The mineral corrensite, which is a regular interstratification of chlorite and smectite layers in a 1:1 ratio, occurs in reservoir sandstones and, in the same way as chlorite, forms pore lining aggregates where there are an abundance of edge-to-face contacts between individual platy particles, thus forming a cellular, honeycomb-type morphology . “di,trioctahedral chlorite” has a dioctahedral 2:1 layer and a trioctahedral interlayer (e.g., the Li chlorite cookeite). While fluid pressure has the capability to reduce the effective stress state and promote slip, mineralogic properties of fault-related rocks can similarly affect fault behavior by introducing weak mineral phases at interfaces. Program, an effort to evaluate the subsurface secondary mineral distribution and nature of alteration at the active TAG mound, located at 26°N latitude on the Mid-Atlantic Ridge. However, laboratory experiments conducted at appropriate temperatures and pressures on hydrated chlorite-smectite phases will be needed to test this hypothesis, which would require artificial samples rather than naturally exhumed (or shallowly drilled) samples, which have typically been altered since their initial formation. Microstructures and chemistry were investigated on selected samples by SEM, HRTEM, and analytical electron microscopy (AEM). Gouge samples between 3296.6 m and 3299.1 m MD are similar to material occurring in the upper active fault zone area. The last one is considered a very common type of reservoir rock for oil and gas. Clay minerals in the S, P and G reservoirs in it mainly include illite, chlorite (or S/Ch) and small amounts of S/I, occasionally with trace amounts of kaolinite. The terms are seldom used and the ortho prefix is somewhat misleading as the chlorite crystal system is monoclinic and not orthorhombic. The negative charge of the layers is a result of silica . We propose, therefore, that smectite-bearing clay coating, and in particular the chlorite-smectite minerals formed by the dissolution of mafic lithologies, governs brittle fault behavior down to the brittle-plastic transition. Chlorite is a DBP formed with chlorine dioxide treatment, and it is currently regulated at 1.0 mg l−1 in the United States. Chlorites with dioctahedral 2:1 layers and trioctahedral interlayer sheets are called ditrioctahedral chlorite (the reverse, tri-dioctahedral chlorite is unknown). In sandstone acidizing, chlorite clay mineral caused iron hydroxide precipitation inside the cores during treatment with mud acid. The 3191 m MD sample from the southwest deformation zone contains chlorite-smectite minerals that are more Fe-rich than the La Palma rock suite, with a narrow range of MgO/(MgO + FeO) values lying between 0.19 and 0.45. Solid circles are anhydrous phases, open circles are hydrous phases. Despite these difficulties, reliable information about stability, formation mechanisms, and structural features of smectitic clays has been gained from the study of single-phase specimens (Kloprogge et al., 1999). Images and analyses of core samples from phase III core are available in the phase III Core Photo Atlas (www.Earthscope.org/safod), and other recent publications (e.g., Chester et al., 2010; Hadizadeh et al., 2010; Schleicher et al., 2010; Bradbury et al., 2011; Holdsworth et al., 2011; Janssen et al., 2011; Mittempergher et al., 2011). Chlorite schists or less common tremolite schists are present west of Kawtaung in the Tawma Chaung, west of Shwedaung and in the Seywa Chaung, and west of Wuntho. With increasing pressure at lower temperatures, however, a new hydrous magnesium aluminosilicate is stabilized (Mg-s in Figure 21). Chlorite occurs naturally in a variety of locations and forms. Illite can break down and migrates in the cores during the acid injection. It is increasingly recognized that clay minerals play an important role in fault weakening behavior, which increases with the number of water layers stored in interlayer sheets of smectite (e.g., Wu et al., 1975; Saffer and Marone, 2003; Ikari et al., 2007; Morrow et al., 2007; Collettini et al., 2009). They are known as hydrous phyllosilicate having silica, alumina and water with variable amount of inorganic ions like Mg2+, Na+, Ca2+ which are found . A multi-disciplinary investigation into the role of provenance on clay distribution in Ravenglass estuary in North West England employed a range of techniques including clay mineralogy, process sedimentology, surface water and sediment ... Some areas in the fault gouge show characteristic wavy chlorite-smectite particles of 10–30 nm average thickness, surrounding and partly replacing small chrysotile minerals (Fig. More extensive work on a variety of materials has been an important part of evaluating the role of clays in controlling friction (Lupini et al., 1981; Brown et al., 2003; Saffer and Marone, 2003). It occurs along with illite in midwestern soils. They occur as products of hydrothermal alteration of minerals such as biotites, amphiboles, pyroxenes, olivines, and other ferromagnesian . Saccaramb, Romania. Chlorite is a common authigenic mineral lining the pores of sandstones. Accordingly, montmorillonite, beidellite and expandable 2: 1 -type minerals were included into smectite, and chlo- In a small number of chlorites, however, the number of octahedral cations is < 10; these varieties are described as dioctahedral. They are commonly found in low- to medium-grade metamorphic rocks and in altered igneous rocks. Chlorite classification is further complicated by the existence of different stacking polytypes. Brace, Comparison of smectite- and illite-rich gouge frictional properties: Application to the updip limit of the seismogenic zone along subduction megathrusts, Laboratory results indicating complex and potentially unstable frictional behavior of smectite clay, The smectite to chlorite transition in a fossil seamount hydrothermal system: The basement complex of La Palma, Canary Islands, Origin and significance of clay-coated fractures in mudrock fragments of the SAFOD borehole (Parkfield, California), Constraints on mineralization, fluid-rock interaction and mass transfer during faulting at 2–3 km depth from the SAFOD drill hole, On the origin of mixed-layered clay minerals from the San Andreas fault at 2.5–3 km vertical depth (SAFOD drillhole at Parkfield, California), Contributions to Mineralogy and Petrology, Nanocoatings of clay and creep of the San Andreas fault at Parkfield. The rock samples are dark-grayish black and intensely sheared with a wavy foliation and a micro-scaly fabric. Based on rock texture, composition, and the presence of fossils at ∼3360 m MD, these rocks have been identified as the Cretaceous Great Valley Group (K. Mc Dougall, 2006, written commun., inDraper-Springer et al., 2009). This paper presents results of acid stability studies conducted with chlorite, illite, and kaolinite clays. This clay is probably more abundant than either illite or smectite. Clays and Clay Minerals in Natural and Synthetic Systems Once again the chlorites have quite a variable chemical compositions and like glauconite a lot of the aluminium is normally replaced by magnesium and iron (other metals including zinc, manganese and nickel replace aluminium can also do this. This gives the apparently contradictory situation of a sand with high water saturations that produces dry hydrocarbons at prodigious rates. References and Links The crystallite sizes of these clay mineral packs are notably thin (<14 layers), with an average defect-free distance of just 4 layers. Chlorite is a common to abundant mineral in low- to intermediate-grade metamorphosed mafic and ultramafic rocks. Fig. The general formula is (K, H)Al2(Si, Al)4O10(OH)2 - xH2O, where x represents the variable amount of water that this group could contain. van der Pluijm, L.N. This sheet is positively charged because there are fewer than 3 OH− per Al3+ in the sheet. Although the average amount of smectite present in chlorite-smectite close to or within the creep zones typically varies between 20% and 50%, as determined by XRD, there is very strong heterogeneity in the smectite content of individual chlorite-smectite particles within any one given sample (Fig. The topics discussed are: *Clays in industry and the environment *Surface and interlayer reactions *Clay mineral structures and chemistry *Methods of investigation *Clays in geology *Soil mineralogy The emphasis of this book reflects the ... The book chapters have been classified according to their characteristics in topics and applications. Therefore, in the first section five chapters is dedicated to the characterization and utilization of clay minerals in deposits. QUANTITATIVE MICROCHEMICAL ANALYSES OF CHLORITE AND CHLORITE-SMECTITE USING WEIGHT PERCENT OXIDES, CALCULATED BASED ON 14 OXYGENS. These minerals are all apart of the Chlorite Group of minerals. ), Using drill cutting separates to estimate the strength of a narrow shear zone at SAFOD, HRTEM evidence for the process and mechanism of saponite-to-chlorite conversion through corrensite, Fault structure, microearthquake recurrence and deep fault slip surrounding the SAFOD target, Diagenesis and low-grade metamorphism of shale and slates, Minerals and Reactions in Atomic Scale: Transmission Electron Microscopy, Mineralogical Society of America, Reviews in Mineralogy, Considerations and applications of the illite-smectite geothermometer in hydrocarbon-bearing rocks of Miocene to Mississippian age, Compositional end members and thermodynamic components of illite and dioctahedral aluminous smectite solid solutions, A chemical and thermodynamic model of dioctahedral 2:1 layer clay minerals in diagenetic processes: Dehydration of smectite as a function of temperature and depth in sedimentary basin, The calculation of one-dimensional X-ray diffraction patterns of mixed-layered clay minerals: Computer program, Fault stress states, pore pressure distributions and the weakening of the San Andreas fault, Fault Mechanics and the Transport Properties of Rocks: A Festschrift in Honor of W.F. Chlorite-smectite 001 reflections range from 1.42 to 1.45 nm in all samples investigated, which expand to 1.45–1.50 nm after ethylene glycolation. A massive compact variety of clinochlore used as a decorative carving stone is referred to by the trade name seraphinite. Chlorite classification is further complicated by the existence of different stacking polytypes. Figure 13. This prediction was confirmed by the experimental results of Pawley (2003) (solid line, Figure 22). Here, we propose the potential role of other clay mineral phases in the fault zone in terms of their formation conditions and stability at depth, and in particular highlight the implications of the chlorite-smectite mixed-layer minerals for understanding faulting mechanisms down to the brittle-ductile transition zone. R2 (ABA) has not been positively identified. Chlorite can also occur as a result of hydrothermal alteration of any rock type, where recrystallization of clay minerals or alteration of mafic minerals produce chlorite. INrnooucrtow Chlorite occurs commonly as a constituent of soil clays and as an impurity in so-called. Copyright © 2021 Elsevier B.V. or its licensors or contributors. Many illite-smectite packets display a long-range ordering, mostly R1–R3, characterized by the reoccurrence of single smectite layers stacked optically parallel between 2–5 illite layers. Abstract The Devonian-Carboniferous reservoir of the Clair Field contains a complex and variably abundant clay mineral assemblage. We surmise that the surrounding packages of 30–50-nm-thick chlorite-smectite precipitated as a lower-temperature reaction product from chrysotile. D'Alessio and Williams (2007) explored the exhumation history at the SAFOD site using thermochronometry and concluded that the area has experienced less than 1 km of exhumation or burial since the onset of the San Andreas fault activity at ca.
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