Mica Content Research Articles

Source, tectonic setting, and facies distribution of the Silurian Sharawra Formation, the Old Qusaiba village, central Saudi Arabia

Three outcrops of the Silurian Sharawra Formation at its type locality in Old Qusaiba Village in Central Saudi Arabia were studied for lithofacies distribution, petrographical, and geochemical characteristics. The outcrops were logged and nine different lithofacies were identified in the field. Petrographic analysis shows the Sharawra Formation to be mainly subarkosic associated with increasing mica content near to its contact with the underlying Qusaiba Shale Formation. Major and trace element geochemistry indicates that the sediments of the formation were deposited in a passive continental margin. The source area discriminating plots reveal acidic or felsic rocks such as granites as the probable provenance of the Sharawra sediments. The Chemical Index of Alteration (CIA) and Chemical Index of Weathering (CIW) indicate a moderate degree of weathering in the source area of these Silurian sediments. This study provides a baseline for future characterization studies of Paleozoic siliciclastic formations in Saudi Arabia and neighbouring countries.

Three dimensional shape analysis of concrete aggregate fines produced by VSI crushing

We studied the 3-D shape of concrete aggregate fines with particle sizes between 3μm and 250μm produced by high-speed vertical shaft impact (VSI) crushing of rock types from 10 different quarries representing a wide range of local Norwegian geology with respect to mineralogy and mechanical properties. This included igneous (intrusive and extrusive), metamorphic, and sedimentary rocks that were both mono- and multi-mineralic. VSI crushing seems to be able to generate concrete aggregate fines of very similar equidimensional mean shape characteristics for the whole analysed size range, independent of the mineralogical composition of the rocks included in the study. The effect on normalising the average particle shape was somewhat lower for the particle size range smaller than about 15μm, where there seems to be a greater influence of the crystallographic structure of the individual minerals. Particles of the rock type containing the highest mica content (5.5%, by mass) had the least equidimensional shape. The most equidimensional shape in a given particle size range was found for both limestone rock types that were analysed. A new shape parameter, the micro-Flakiness Index (μFI), has been proposed to characterize the shape of the fine crushed concrete aggregate particles to enable practical use of shape parameters.

Structural study of mullite based ceramics derived from a mica-rich kaolin waste

Mullite-based ceramics have been synthesized by reactive sintering of a mixture containing kaolin and a mica-rich kaolin waste. Samples fired in the temperature range from 1300 to 1500°C were characterized by X-ray diffraction (XRD). The quantitative phase analysis and unit cell parameters of the mullite were determined by Rietveld refinement analysis of the XRD data. Mullite-based ceramics with 1.2wt% quartz, 56.3wt% glass (amorphous phase), 2.64g/cm3 of apparent density, and 35±1.2MPa of flexural strength were obtained after firing at 1500°C. A liquid phase sintering mechanism activated by a total mica content of 13.3wt% allowed to increase the mullite content to 47.6wt% (2.3wt% quartz and 50.1wt% glass phase) and improve the flexural strength (70±3.9MPa) after firing at 1400°C.

Synthesis, characterisation and enhanced properties of polyimide/mica hybrid films

ABSTRACTPolyimide/mica (PI/mica) hybrid films were prepared from pyromellitic dianhydride/4,4-bis(3-aminophenoxy)biphenyl (PMDA/4,3-BAPOBP) and mica in a solution of N,N-dimethylacetamide. The structure–property relationships of the composites were studied by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible spectroscopy and differential scanning calorimetry. FTIR indicated successful preparation of PI/mica hybrid films. XRD and SEM results indicated that the mica was well dispersed in the PI matrix. The dependence of morphology, glass transition temperatures (Tg), dielectric properties and mechanical properties at room temperature of the hybrid films on the content of mica was discussed. It was observed that Tg, the breakdown strength and tensile strength of the hybrid films, could be simultaneously increased when the mica content was lower than 8 wt-%. Meanwhile, the dielectric constant and dielectric loss of PI/mica hybrid films increased with the increase in the mica content.

How is strain localized in a meta-granitoid, mid-crustal basement section? Spatial distribution of deformation in the central Aar massif (Switzerland)

This study investigates strain distribution in granitoid rocks formerly in the middle crust in the Central Aar massif, Switzerland and places the deformation behavior in the tectonic framework of the Alpine orogeny. Strain is heterogeneously distributed in terms of strain partitioning forming several hundreds of closely spaced shear zones (SZ) (>80 SZ/km with SZ thicknesses <10 cm; about 10 SZ/km with SZ thicknesses of 0.5–10 m) separating 3D bodies of low to moderate background strain. Both the degree of background-strain intensity as well as the number of shear zones increases from granitic to granodioritic host rocks and is controlled by primary variations in the mica content between 10 and 15 vol% (granodiorite) and <8 vol% (granite). Shear zones evolved from ductile shearing in granodiorites, whereas they often nucleated from fractures in the stronger granites.The majority of the steep shear zones preferentially accommodated upward motion by the southern block leading to an increase in peak metamorphic conditions from 250 °C in the North to 450 °C in the South of the Aar massif. The shear zones initiated at about 18–20 km depths during a stage of crustal thickening (Handegg phase). Subsequent deformation reactivated some shear zones with a gradual transition from reverse dip-slip over oblique-slip to strike-slip shear zones under local transpressional conditions (Oberaar phase).

Preparation of mullite based ceramics from clay–kaolin waste mixtures

Mullite based ceramics were prepared by reaction sintering of mixtures containing kaolin clay and kaolin waste. Phase composition, apparent density, apparent porosity, and modulus of rupture were investigated as a function of sintering temperature and kaolin waste content (varied from zero to 50wt%). The sintering shrinkage behavior was monitored by dilatometry. The results showed that samples derived from formulations containing kaolin waste were composed of acicular mullite and glass phases at 1500°C. Ceramic bodies prepared with kaolin waste (25 or 50wt%) showed better physico-mechanical properties (for sintering up to 1400°C) than the ones of pure kaolin clay. The evidence seems to suggest that this behavior can be due to a liquid phase assisted sintering mechanism associated with a content of mica ranging from 13.3 to 22.4wt%.

Nanocomposites of Polyethylene Blends Using Organomica

SummaryThis study aims to incorporate LLDPE into HDPE in order to improve its processability, as well as to employ a nanoclay for maintaining the HDPE stiffness. Thermal, dynamic‐mechanical and rheological properties of polyethylene composites were investigated. Muscovite mica was treated with lithium nitrate for seven cycles, followed by exchange with quaternary ammonium salt to produce organomica. Initially, organomica was added to HDPE at 2% wt. using a tween‐screw mini‐extruder. The blend HDPE/LLDPE (1:1 by weight) was also evaluated at the same mica content, with and without the introduction of maleated polyethylene (PEMA) as compatibilizer in order to increase adhesion of polymers with the mineral clay. The samples were evaluated by thermogravimetry (TGA), while melting and crystallization temperatures, and the degree of crystallinity were measured by differential scanning calorimetry (DSC). Rheological properties were evaluated during blending using viscosity and torque curves as a function of processing time. The results showed that stability to thermal degradation of the polyethylene blend with mica increased with the addition of 2% wt. PEMA, where the temperature of maximum degradation rate overcame that of HDPE. The melting endotherm remained narrow in the mixture HDPE/LLDPE/mica, showing good miscibility of the polymer blend; and there was a slight decrease in the melting temperature. The reduction in viscosity during blending revealed improved processing conditions.

Geochemistry of the sandstones of Punagarh basin: Implications for two source terranes and Arabian - Nubian connection of Aravalli craton?

Sandstones of Punagarh basin of Trans Aravalli region, NW Indian shield were analyzed for their major and trace element contents in conjunction with petrographic modes. The Punagarh basin comprises four formations (Sojat, Bambolai, Khamal and Sowania), amongst which the Sojat Formation in uncoformable contact with overlying formations, is significantly older and enjoys separate status as rest of the formations constitute Punagarh Group. Petrographic attributes suggest that Sojat sandstones contain distinct modal abundances like high content of quartz and low content of feldspar, mica, matrix, rock fragments and cement. In general there is a decrease in the average modal abundance of quartz and mica with concomitant increase of feldspar, chert and rock fragments from base to top in Punagarh sandstones. Sojat sandstones are also geochemically distinct as they possess high SiO2/Al2O3, Th/U and Cr/Th ratios coupled with lowest Na2O/K2O ratio and Zr content, least fractionated LREE, more fractionated HREE and largest Eu* anomaly compared to Punagarh sandstones. The weathering indices suggest intense chemical weathering for Sojat sandstones and low to moderate for Punagarh sandstones. Compositionally all the sandstones of the Punagarh basin come under the category of quartzarenite. Compared to PAAS and UCC, both suite of sandstones are generally depleted in REE, HFSE (with exception of Zr, Hf and Ta), and enriched in ferromagnesian trace elements particularly Cr and Co. The chemical data indicate that the sediments were derived from the source(s) of mixed felsic - mafic composition, with the former being dominant. The source rocks were granites, TTG, basalts, and rhyolites. The Sojat sandstones owe their source form Archean crust while Punagarh sandstones got detritus from Mesoproterozic crust. Immobile element ratios and REE abundances of Sojat sandstones closely match with Paleoproterozoic metagreywackes of Ghana of African craton while Punagarh sandstones show near geochemical characteristic with Gogunda, Kumbalgarh and Vindhyan quartzites of Aravalli craton. This geochemical similarity of Sojat sandstones provides credence to the hypothesis that Trans–Aravalli region of India had been an integral part of Arabian - Nubian shield. The chemical data advocate the deposition of these sandstones in a tectonic setting comparable to modern back arc setting.

Microstructural, modal and geochemical changes as a result of granodiorite mylonitisation – a case study from the Rolovská shear zone (Čierna hora Mts, Western Carpathians, Slovakia)

Abstract Strong tectonic remobilisation and shear zone development are typical features of the easternmost part of the Veporicum tectonic unit in the Western Carpathians. The granodiorite mylonites in the area of the Rolovská shear zone (Čierna hora Mts) underwent a complex polystage evolution during the Hercynian and Alpine orogenies. Deformation during the latter reached greenschist facies under metamorphic conditions. Mylonites are macroscopically foliated rocks with a stretching lineation and shear bands. Structurally different mylonite types, ranging from protomylonites to ulramylonites with typical grainsize reduction from the margins towards the shear zone centre, have been assessed. The modal mineralogy of the different mylonite types changes considerably. Typical is a progressive decrease in feldspar content and simultaneously the quartz and white mica content increases from protomylonites towards the most strongly deformed ultramylonites. The deformation had a brittle character in less deformed rocks and a ductile one in more deformed tectonites. Obvious chemical changes occur in mesomylonites and ultramylonites. During mylonitisation, the original biotite granodiorite was depleted of Mg, Fe, Na, Ca and Ba, while K, Rb and mainly Si increased considerably. Other (major and trace) elements reflect erratic behaviour due to lateral mobility. Chemical changes indicate the breakdown and subsequent recrystallisation of biotite and feldspars and, in turn, the crystallisation of albite and sericite. REE decrease in ultramylonites due to the breakup of accessory minerals during deformation and alteration.

Engineering Rock Mass Evaluation for a Multi-purpose Hydroelectric Power Plant: Case of Genale Dawa (GD-3), Ethiopia

In engineering projects such as tunnels, dams, foundations, and slope stability, the strength and elastic properties of the intact rock affect both the project design and the construction operation. Geological, geophysical and geotechnical study have been carried out for construction of multipurpose hydroelectric power plant at Genale–Dawa (GD-3) on the Genale River with the goal of generating 254 MW of hydroelectric power and providing irrigation water for downstream agriculture. The dam site is located on massive pegmatoidal granites with minimal foundation excavations and minimal grouting requirements. Weathering at the dam site is generally less than about 5 m. In general the Lugeon tests have shown that the rock mass at the dam site is generally tight below 6 m but this could extend to 10 m or possibly more in places. In the power house area weathering extends to about 15 m on the ridge and about 9 m in proximity to the river. This deeper weathering is probably due to the presence of schists within the granites as the foliated schists with significant mica content are more prone to weathering. Point load test, laboratory UCS tests and correlation of P-wave velocity with UCS is considered in assigning the reliable value of rock strength. Combined three input parameters RMR, Q system and RMi system were used for the assessment of the rock mass strength of tunnel and dam foundation. The tunnel will be excavated largely in the pegmatoidal granites with a Rock Mass Classification of “Very Good” to “Good” This is largely due to the massive, relatively un-jointed rock mass of high strength. There is a section of headrace tunnel, of uncertain length and at the surge shaft in proximity to the outlet portal, where significant proportions of the pegmatoidal granites contain remnants of feldspathic and biotite schists, the Rock Mass Classification of this unit is “Fair” to “Good”. The proposed hydropower project is situated in a geologically favorable environment with very suitable foundation and tunneling conditions. The study lists recommendations in relation to testing and rock classification procedures, which are indirectly related to the safety and quality of the hydropower infrastructure.

Rheological properties and curing features of natural rubber compositions filled with fluoromica ME 100

This work aims at studying not only the rheological behavior of natural rubber-based compositions by making use of different contents of fluoromica or ME 100 synthetic mica in a natural rubber (NR) matrix, but also the different filler-filler and matrix-filler interactions before and after curing. The ME 100 content in NR varied from 0 to 10 phr (parts per hundred parts of resin) and the results enabled to conclude on the influence of the mineral filler on the curing parameters, as well as on the limit amount of ME 100 for the best performance resulting from the best filler distribution/interaction in the polymer matrix. All data were compared with those of the unfilled composition. Based on complex viscosity, curing parameters, dynamic modulus and Payne effect tests it was concluded that the mica content limit for the best performance was 7 phr.

Mud-Dominated Basin-Margin Progradation: Processes and Implications

Abstract The accretion of coarse-grained material at the shelf-edge rollover has been emphasized in studies of basin-margin progradation, despite fine-grained sediment (clay and silt) representing a volumetrically more significant component of subaqueous clinothems. The timing and processes of fine-grained sediment transport across the shelf and onto the slope remains an understudied facet of sedimentary-basin stratigraphy. Three exhumed basin-margin-scale clinothems of the Permian Waterford Formation, in the Karoo Basin, South Africa, offer outcrop examples of margin development through the accretion of mud during flooded shelf conditions. The progradation of wave-influenced sandy shelf topset deposits over a thick mudstone succession and beyond a previously established sand-rich shelf-edge rollover suggests that some periods of basin-margin progradation took place exclusively via dilute mud-rich gravity flows. Detailed outcrop and core study of offshore mudstones reveals a high content of organic debris and mica. Individual beds show normal and inverse grading, internal erosion surfaces, and moderate to low bioturbation, reflecting relatively stressed conditions in frequently supplied outer-shelf to upper-slope regions. The estimated low gradient (< 0.7°) of the Karoo Basin margin and prevailing wave and/or storm conditions facilitated prolonged suspension of fluid mud and transport across the shelf and beyond the shelf-edge rollover in sediment gravity flows. This study represents a rare example of mudstone-dominated shelf-edge rollover deposits documented at outcrop and core, and demonstrates how accretion of fine-grained sediment can play a significant role in basin-margin progradation. Conventional depositional models do not adequately account for progradation of basin margins in the absence of sand supply, which implies potential risks in the identification of shelf-edge rollover positions and application of trajectory analysis in strongly progradational margins.

The reclamation of mica flakes from tailing disposal using gravity separators and flotation

A sample from the small-sized tailing pile of an Iranian mica processing plant was subjected to a series of mica recovery experiments. Mineralogical and microscopic investigations indicated that the dominant mica mineral was phlogopite which was accompanied by plagioclase feldspars. Before beneficiation studies, the particle size distribution of the representative sample was obtained, and the specifications of each size fraction were investigated in detail. It was observed that the largest portion of mica (31%) is accumulated in the size range of 0.3 to 2.0 mm. Afterward, gravity concentration and flotation experiments were carried out. Results proved that shaking table could produce a mica concentrate with grade of 74%. Also, according to the flotation tests, it seemed the best size fraction was -150+75, and after that, -100+150. Flotation in combination with attrition scrubbing produced a concentrate with 92% mica content and 70% recovery. Finally, with respect to the results of all implemented experiments, a processing flow sheet was proposed for mica reclamation from the mentioned waste disposal.

Mica-dominated seismic properties of mid-crust beneath west Yunnan (China) and geodynamic implications

Measurements of crystallographic preferred orientations (CPO) and calculations of P- and S-wave velocities (Vp and Vs) and anisotropy were conducted on three quartz–mica schists and one felsic mylonite, which are representative of typical metamorphic rocks deformed in the middle crust beneath the southeastern Tibetan plateau. Results show that the schists have Vp anisotropy (AVp) ranging from 16.4% to 25.5% and maximum Vs anisotropy [AVs(max)] between 21.6% and 37.8%. The mylonite has lower AVp and AVs(max) but slightly higher foliation anisotropy, which are 13.2%, 18.5%, and 3.07%, respectively, due to the lower content and CPO strength of mica. With increasing mica content, the deformed rocks tend to form transverse isotropy (TI) with fast velocities in the foliation plane and slow velocities normal to the foliation. However, the presence of prismatic minerals (e.g., amphibole and sillimanite) forces the overall symmetry to deviate from TI. An increase in feldspar content reduces the bulk anisotropy caused by mica or quartz because the fast-axis of feldspar aligns parallel to the slow-axis of mica and/or quartz. The effect of quartz on seismic properties of mica-bearing rocks is complex, depending on its content and prevailing slip system. The greatest shear-wave splitting and fastest Vp both occur for propagation directions within the foliation plane, consistent with the fast Pms (S-wave converted from P-wave at the Moho) polarization directions in the west Yunnan where mica/amphibole-bearing rocks have developed pervasive subvertical foliation and subhorizontal lineation. The fast Pms directions are perpendicular to the approximately E-W orienting fast SKS (S-wave traversing the core as P-wave) directions, indicating a decoupling at the Moho interface between the crust and mantle beneath the region. The seismic data are inconsistent with the model of crustal channel flow as the latter should produce a subhorizontal foliation where vertically incident shear waves suffer little splitting.

Graphite‐schist blocks in the Franciscan Mélange, San Simeon, California: Evidence of high‐P metamorphism

AbstractThe seacliff exposure at San Simeon, California, contains graphite‐schist blocks in a shale‐matrix, an undocumented lithology within the Franciscan mélange. Thirty graphite‐schist blocks were studied to discover all the varieties in this classic locality of mélange. Based on their mineralogical assemblage and composition, and textural characteristics the graphite‐schists in San Simeon are subdivided into two main types (Type I and II) with two subdivisions each (A and B). Type IA and IIA blocks are the most abundant. Type IA graphite‐schists are siltstone/fine greywacke‐like, preserve sedimentary textures, and lack lawsonite. Type IB graphite‐schists are mineralogical and texturally similar to Type IA schists, but are finer grained siltstone and shale. Type IIA graphite‐schists are compositionally layered and contain quartz‐ and albite‐rich layers and dark graphite‐ and intergrown mica/chlorite‐rich layers. Nine out of the 15 Type IIA blocks contain lawsonite. Two Type IIA blocks also contain aragonite (+calcite) in veins. Type IIB graphite‐schists are mostly composed of quartz and minor graphite, intergrown chlorite and white mica, and white mica pseudomorphs after lawsonite. The phengite content of mica in Type IIA blocks is higher than that of mica in Type IA graphite‐schists, confirming they were metamorphosed under high‐P/low‐T conditions. Type IA blocks were recrystallized between 200 and 250 °C at &lt;~3 kbar; whereas, Type IIA blocks were metamorphosed under higher pressure conditions, probably at 250–300 °C and 3–5 kbar. Most likely both types of graphite‐schists were derived from a similar layered siltstone/fine greywacke/shale protolith. Organic matter‐rich sediments deposited in the trench axis were subducted along with oceanic crust during Franciscan subduction. Type I graphite‐schists were subducted to depths &lt;10 km, whereas Type II graphite‐schists were subducted to depths ~15 km where they were underplated under high‐P conditions. The graphitic metasedimentary rocks were juxtaposed with mafic lithologies from the subducted oceanic crust that were metamorphosed to blueschist facies and retrograded to greenstone as they returned to the surface in the subduction channel shear zone.

Mineral chemistry and magnetic petrology of the Archean Planalto Suite, Carajás Province – Amazonian Craton: Implications for the evolution of ferroan Archean granites

The Planalto Suite is located in the Canaã dos Carajás subdomain of the Carajás Province in the southeastern part of the Amazonian Craton. The suite is of Neoarchean age (∼2.73 Ga), ferroan character, and A-type affinity. Magnetic petrology studies allowed for the distinction of two groups: (1) ilmenite granites showing low magnetic susceptibility (MS) values between 0.6247×10−3 and 0.0102 × 10−3 SI and (2) magnetite-ilmenite-bearing granites with comparatively higher but still moderate MS values between 15.700×10−3 and 0.8036 × 10−3 SI. Textural evidence indicates that amphibole, ilmenite, titanite, and, in the rocks of Group 2, magnetite also formed during magmatic crystallization. However, compositional zoning suggests that titanite was partially re-equilibrated by subsolidus processes. The amphibole varies from potassian-hastingsite to chloro-potassian-hastingsite and shows Fe/(Fe + Mg) > 0.8. Biotite also shows high Fe/(Fe + Mg) ratios and is classified as annite. Plagioclase porphyroclasts are oligoclase (An25-10), and the grains of the recrystallized matrix show a similar composition or are albitic (An9-2). The dominant Group 1 granites of the Planalto Suite were formed under reduced conditions below the FMQ buffer. The Group 2 granites crystallized under more oxidizing conditions on or slightly above the FMQ buffer. Pressures of 900–700 MPa for the origin and of 500–300 MPa for the emplacement were estimated for the Planalto magmas. Geothermometers suggest initial crystallization temperatures between 900 °C and 830 °C, and the water content in the magma is estimated to be higher than 4 wt%. The Neoarchean Planalto Suite and the Estrela Granite of the Carajás Province reveal strong mineralogical analogies, and their amphibole and biotite compositions have high total Al contents. The latter characteristic is also observed in the same minerals of the Neoarchean Matok Pluton of the Limpopo Belt but not in those of the Proterozoic rapakivi A-type granites. On the other hand, in terms of the degree of magma oxidation, the Planalto and Estrela granites approach the reduced Mesoproterozoic rapakivi granites and the reduced to moderately oxidized Paleoproterozoic granites of the Velho Guilherme and Serra dos Carajás Suites, respectively, and differ from the oxidized granites (Jamon Suite) of the Carajás Province as well as those of Matok pluton. The high total Al content of amphibole and mica could be caused by crystallization at high pressures that, in turn, can be a reflex of the association of the studied granites and Matok with charnockitic rocks.

Petrographic characteristics of intrusive rocks as an evaluation tool of their technical properties

Abstract The main petrographic variables of intrusive rocks that influence the technical test methods common used within the aggregate industry were identified and evaluated, the aim being to investigate whether petrographic description could be used as a tool for the preliminary quality evaluation of different rock groups. Evaluation of the dependence of the technical test methods on petrographic variables covered 26 intrusive rocks, including some of their altered varieties (orthogneisses), divided into two groups: 17 granitoids and 9 gabbroids. The selective designated samples were analysed to determine their petrographic characteristics and resistance to fragmentation, wear and wear by abrasion from studded tyres. In order to identify the complicated associations between the petrographic and technical properties, multivariate statistical evaluation was performed. The results of statistical evaluation highlighted that mean grain size of mica minerals, grain size distribution, content of mica minerals and mean grain size were the main variables influencing the technical properties of granitoid rocks, while for gabbroid rocks, the main influences were the frequency of microcracks, mica content, grain size distribution and mean grain size.

Geochemical and Petrogenetic Study of Proterozoic Sewariya and Govindgarh Granitoids from South Delhi Fold Belt

The present study reports the geochemical composition of Sewariya two-mica granites (SG) and Govindgarh granites (GG) intruding rocks of Delhi Supergroup along the western margin of South Delhi Fold Belt in Rajasthan, India. Both granite varieties are highly evolved possessing high SiO 2 , Al 2 O 3 , low MgO, CaO, Fe 2 O 3 , Ni, Cr and V and are calc-alkaline in nature. In chondrite normalized REE diagrams, SG are characterized by highly fractionated REE patterns (avg La N / Yb N = 21.45) and sharp negative Eu* anomaly (Eu/Eu* = 0.25), whereas GG do not show significant REE fractionated patterns (avg La N /Yb N = 3.31) and have variable Eu anomalies. From primitive mantle normalized multi-element diagrams, crustal signatures (low Nb, Ti and high Pb, U, Th) can be inferred for both the granitoid varieties. Also, strong peraluminous nature, high A/CNK, normative corundum and abundant mica content point towards a (meta)sedimentary protolith for them. An arc setting is indicated by their calc-alkaline nature; volcanic arc or syncollisional affinities in tectonic discriminant diagrams (Nb versus Y; Rb versus Nb + Y). They are peraluminous leucogranites derived from crustal melts with little mantle contribution as is evident from their mineralogy and geochemical characteristics. The anatectic conditions prevalent during the formation of these granites differed with SG being formed under dehydration conditions, while the formation of GG involved fluid-present melting reactions.

Effect of Mica Content on Mechanical Properties of Regenerated Cellulose Nanocomposites via Ionic Liquids

A series of regenerated cellulose (RC) nanocomposites which were incorporated with the layered silicate mica were successfully prepared via ionic liquid. The effect of the mica loadings was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties which were investigated via tensile testing indicated that upon the introduction of the mica displayed a significant enhancement on the mechanical stability of the RC. The results showed the potential of mica to reinforce the RC polymers matrix.

Seismic properties and mineral crystallographic preferred orientations from EBSD data: Results from a crustal-scale detachment system, Aegean region

The crystallographic preferred orientations (CPOs) were measured on a suite of samples representative of different structural depths along the West Cycladic Detachment System, Greece. Electron backscatter diffraction (EBSD) analyses were conducted on calcitic and mica schists, impure quartzites, and a blueschist, and the average seismic properties of the rocks were calculated with the Voigt–Reuss–Hill average of the single minerals' elastic stiffness tensor. The calcitic and quartzitic rocks have P- and S-wave velocity anisotropies (AVp, AVs) averaging 8.1% and 7.1%, respectively. The anisotropy increases with depth represented by the blueschist, with AVp averaging 20.3% and AVs averaging 14.5%, due to the content of aligned glaucophane and mica, which strongly control the seismic properties of the rocks. Localised anisotropies of very high magnitudes are caused by the presence of mica schists as they possess the strongest anisotropies, with values of ~25% for AVp and AVs. The direction of the fast and slow P-wave velocities occurs parallel and perpendicular to the foliation, respectively, for most samples. The fast propagation has the same NE–SW orientation as the lithospheric stretching direction experienced in the Cyclades since the Late Oligocene. The maximum shear wave anisotropy is subhorizontal, similarly concordant with mineral alignment that developed during extension in the Aegean. Radial anisotropy in the Aegean mid-crust is strongly favoured to azimuthal anisotropy by our results.