Plagioclase Research Articles

МИГРАЦИЯ ТЕХНОГЕННЫХ РАДИОНУКЛИДОВ (137CS, 152EU, 60CO) В ДОННЫХ ОТЛОЖЕНИЯХ Р. ЕНИСЕЙ (БЛИЖНЯЯ ЗОНА ВЛИЯНИЯ КРАСНОЯРСКОГО ГХК)

The distribution nature of the artificial gamma-emitting radionuclides (137Cs, 152Eu, 154Eu, 155Eu, 60Co) in vertical columns of the Yenisei River bottom sediments selected in the near zone of influence of the Krasnoyarsk MCP was revealed. It is shown that the mineral composition of bottom sediments does not change with the depth and is mainly represented by quartz, plagioclase and potassium feldspar, with a small amount of amphibole, chlorite, mica. It was found that the exchangeable and carbonate forms contain, on average, 16% of 152Eu, 22% of137Cs and 15% of 60Co being found in bottom sediments. Radionuclides presented in these forms can pass into an aqueous solution and be involved in secondary migration under stable, natural conditions. Other fractions of the absorbing complex in the absence of catastrophic changes in physico-chemical conditions in the river ecosystem do not pass into an aqueous solution, and the redistribution of radionuclides associated with them can occur only with mechanical transfer of the matter.

Identifying Shocked Feldspar on Mars Using Perseverance Spectroscopic Instruments: Implications for Geochronology Studies on Returned Samples

The Perseverance rover (Mars 2020) mission, the first step in NASA’s Mars Sample Return (MSR) program, will select samples for caching based on their potential to improve understanding Mars’ astrobiological, geological, geochemical, and climatic evolution. Geochronologic analyses will be among the key measurements planned for returned samples. Assessing a sample’s shock history will be critical because shock metamorphism could influence apparent sample age. Shock effects in one Mars-relevant mineral class, plagioclase feldspar, have been well-documented using various spectroscopy techniques (thermal infrared reflectance, emission, and transmission spectroscopy, Raman, and luminescence). A subset of these data will be obtained with the SuperCam and SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) instruments onboard Perseverance to inform caching decisions for MSR. Here, we review shock indicators in plagioclase feldspar as revealed in Raman, luminescence, and IR spectroscopy lab data, with an emphasis on Raman spectroscopy. We consider how this information may inform caching decisions for selecting optimal samples for geochronology measurements. We then identify challenges and make recommendations for both in situ measurements performed with SuperCam and SHERLOC and for supporting lab studies to enhance the success of geochronologic analyses after return to Earth.

An evaluation of the heat test for the ice-nucleating ability of minerals and biological material

Abstract. Ice-nucleating particles (INPs) are atmospheric aerosol particles that can strongly influence the radiative properties and precipitation onset in mixed-phase clouds by triggering ice formation in supercooled cloud water droplets. The ability to distinguish between INPs of mineral and biological origin in samples collected from the environment is needed to better understand their distribution and sources. A common method for assessing the relative contributions of mineral and biogenic INPs in samples collected from the environment (e.g. aerosol, rainwater, soil) is to determine the ice-nucleating ability (INA) before and after heating, where heat is expected to denature proteins associated with some biological ice nucleants. The key assumption is that the ice nucleation sites of biological origin are denatured by heat, while those associated with mineral surfaces remain unaffected; we test this assumption here. We exposed atmospherically relevant mineral samples to wet heat (INP suspensions warmed to above 90 ∘C) or dry heat (dry samples heated up to 250 ∘C) and assessed the effects on their immersion mode INA using a droplet freezing assay. K-feldspar, thought to be the dominant mineral-based atmospheric INP type where present, was not significantly affected by wet heating, while quartz, plagioclase feldspars and Arizona Test Dust (ATD) lost INA when heated in this mode. We argue that these reductions in INA in the aqueous phase result from direct alteration of the mineral particle surfaces by heat treatment rather than from biological or organic contamination. We hypothesise that degradation of active sites by dissolution of mineral surfaces is the mechanism in all cases due to the correlation between mineral INA deactivation magnitudes and their dissolution rates. Dry heating produced minor but repeatable deactivations in K-feldspar particles but was generally less likely to deactivate minerals compared to wet heating. We also heat-tested biogenic INP proxy materials and found that cellulose and pollen washings were relatively resistant to wet heat. In contrast, bacterially and fungally derived ice-nucleating samples were highly sensitive to wet heat as expected, although their activity remained non-negligible after wet heating. Dry heating at 250 ∘C leads to deactivation of all biogenic INPs. However, the use of dry heat at 250 ∘C for the detection of biological INPs is limited since K-feldspar's activity is also reduced under these conditions. Future work should focus on finding a set of dry heat conditions where all biological material is deactivated, but key mineral types are not. We conclude that, while wet INP heat tests at (>90 ∘C) have the potential to produce false positives, i.e. deactivation of a mineral INA that could be misconstrued as the presence of biogenic INPs, they are still a valid method for qualitatively detecting very heat-sensitive biogenic INPs in ambient samples if the mineral-based INA is controlled by K-feldspar.

The early Eocene (48\xa0Ma) Qaladeza trondhjemite formed by wet partial remelting of mafic crust in the arc-related Bulfat Igneous Complex (Kurdistan, Iraq): constraints on the timing of Neotethys closure

Events in the tectono-magmatic framework of the Eocene Bulfat Igneous Complex in the Kurdistan region of northeastern Iraq are revealed through the integrated field, petrographic, geochemical and zircon petrography and U–Pb geochronology of the Qaladeza trondhjemite sheets that cut gabbros of the complex. The trondhjemite sheets are variably deformed, with the cataclasis of large plagioclase feldspars. The trondhjemites are albitic, and geochemical features such as strong enrichment of the light REE relative to the heavy REE and low Ti and REE content show that they did not form as late differentiates of a MORB-like source, but instead by hydrous partial melting of mafic rocks, possibly also involving some more evolved crustal source as well. Qaladeza trondhjemite oscillatory-zoned magmatic zircon has an age of 48.0 ± 0.6 Ma (95% confidence). These domains have been etched to form voids in the zircons, the walls of which have thin coatings of Th- and Ca-bearing species. Subsequent partial recrystallization of the zircons obliterated the voids and increased the Th/U of the recrystallized zircon, which mostly formed at 38.74 ± 0.74 Ma. The 48 Ma domains relate to recycling of mafic crust in a proto-arc tectonic setting and are congruent with Eocene proto-arc magmatic activity within the Neotethyan oceanic basin. The 39 Ma domains relate to later tectonic-induced recrystallisation events coeval with the closure of Neotethys resulting from the late Eocene collision between the Arabian plate and Eurasia in Kurdistan.

A2-Type Granites from the Bastar Craton, South-Central India, and Their Implication in Archean-Paleoproterozoic Tectonics in Indian Peninsula

Abstract This communication reports novel geochemical and geochronological data of granite from the southeastern part of the Bastar Craton, Central India. The studied samples are leucocratic in appearance and composed of quartz, K-feldspar, plagioclase feldspar, and biotite in decreasing order of abundances. Apatite, sphene, and zircon occur as accessory minerals. The SiO2 and Al2O3 content of the studied sample varies between 61 and 69 wt.% and 13 and 15 wt.%, respectively. The alkali oxides, K2O, and Na2O content ranges between 3 and 6 wt.% and 2 and 3 wt. %, respectively. In the primitive mantle normalized spider diagram, the granites exhibit a negative Nb–Ti, Sr anomaly, and a positive Pb–Th anomaly. Similarly, in the REE normalized spider plot, the granites exhibit a strongly fractionated trend La/YbCN=10.90−28.4 with a negative Eu anomaly (0.42-0.70). The zircon saturation in silicate melt yields crystallization temperature (Tzr) ~650 to 800°C for the Eastern Bastar Craton rocks. The P-T pseudosection modeling implies EBC granites which are crystallized at 700-750°C, at 0.4 to 0.6 GPa. The SHRIMP U-Pb ages from magmatic zircon yield an upper intercept at ~2470 Ma and a lower intercept at ~2100 Ma. When combined with the results of P-T pseudosection modeling, the geochemical and geochronological data classifies the Eastern Bastar Craton rocks as A2 granites that were emplaced during the amalgamation of Archean blocks leading to extended Ur formation. The ~2100 Ma age is correlated with mafic dyke emplacement and the Bastar Craton–Yilgarn Craton block disintegration before Paleoproterozoic Columbia supercontinent assembly.

Can long-term fertilization accelerate pedogenesis? Depicting soil processes boosted by annual NPK-inputs since 1928 on bare loess Luvisol (INRAE-Versailles)

Human activities worldwide menace beneficial soil ecosystem services, but long-term anthropogenic impacts on soil properties and processes are often difficult to assess in field conditions. Here we exploited INRAE’s patrimonial ‘42-plots’ bare-fallow experiment, an unique long term experiment in the world created in 1928 in Versailles (France), to emphasize long-term impacts of annual inputs of NPK fertilizers (ammonium, phosphate, potassium salts) and basic amendments (lime, basic slag) on loess Luvisols. We selected plots receiving monovalent (Na+, K+), acid (NH4+), basic (Ca2+) and non-amended (reference) plots, thus embracing the today widely diverging physicochemical surface soils conditions. Temporal changes of soil characteristics were studied on historical archived topsoil samples, whereas soil-depth impacts were studied on samples from subsurface horizons collected in 2015 until 120-cm depth. Bare-fallow management caused a rapid organic matter (OM) decay, soil acidification, CEC reduction and lixiviation of cations. With reduced OM-buffering capacities, specific fertilizer-induced physicochemical conditions enhanced the development of several soil-forming processes. NH4-fertilizers amplified soil acidification (pH < 4), lixiviation (i.e. 1.5 kg m−2 of Ca), aluminization of the exchange complex, and weathering of ferromagnesian minerals and plagioclase feldspars. Under (NH4)2HPO4 fertilization, a quasi-total dissolution of chlorite and hornblende occurred, pointing to an acidocomplexolysis process in which the PO43- anion likely plays the role of complexing organic acids in Podzols. Ammonium fertilizers also affected E, B and C horizons. In reference plots, similar but lower effects remained restricted to the surface horizon. Na/K-fertilizers favoured substantial clay translocation (i.e. 10–15 kg m−2) from the Ap to underlying E and E/Bt horizons. Liming amendments counteracted acidifying effects of OM-depletion, and raised the pH to 8–8.5 and exchangeable Ca to >95%. It may be clear that the initial design specifications do not allow a direct comparison with current conditions of agricultural soils. However, in the view of global climate change, foreseeing a lowering of organic carbon contents in soils, the 42-plots trial acts like an “alert launcher”, forecasting risks of soil degradation with respect to mineral soil phases, parameters and processes, generally buffered and masked by the presence of organic matter. The 42-plots experiment forms a high-valued playing field for experimental research, offering a unique centennial time-span of differing physicochemical properties in a soil context with close initial pedogenetic connexion.

The production technology of mineral soda alumina glass: A perspective from microstructural analysis of glass beads in Iron Age Taiwan.

Mineral soda alumina (m-Na-Al) glass is a common glass production group found around the Indo-Pacific region. In Iron Age Taiwan, its presence dates back to the early 1st millennium AD. This research discusses m-Na-Al glass beads excavated from Iron Age sites in Taiwan. No production sites for m-Na-Al have been found, but microstructural analysis suggests m-Na-Al glass appears to originate around South Asia and is exchanged widely. SEM-EDS and EPMA were used to analyse red, orange, yellow, green and blue m-Na-Al glass. The microstructure of the glass shows the presence of plagioclase and alkali feldspar relics in the glass, suggesting a low manufacturing temperature. Copper-based colourants are identified in red, orange, blue and green glass, while lead tin oxide is used in yellow and green glass. It appears that various types of copper-containing raw materials were procured by craftspeople, and a self-reduction process for producing red and orange glass is tentatively proposed. Additionally, the microstructure of yellow glass reveals different colouring paths were used. These results increase our understanding of the selection of raw materials, and provide an impetus for further research on the cross craft interaction between glass and copper production.

Thermal impact of dykes on ignimbrite and implications for fluid flow compartmentalisation in calderas

Ignimbrites within calderas host intrusions with hazardous and/or economically significant hydrothermal systems. The Hvítserkur ignimbrite at Breiðuvík caldera, north-eastern Iceland, is intruded by basaltic dykes. Our data show that the ignimbrite immediately adjacent to the dyke is hard, dark-coloured, recrystallised quartz, plagioclase, and alkali feldspar with a low permeability and porosity and frequent macrofractures. At 1-2 m from the dyke, the ignimbrite is hard, dominantly glassy with pervasive perlitic microfractures, has high permeability, but low porosity and frequent macrofractures. A narrow zone of pervasive unlithified clay exists 2 m from the dyke. Beyond this, the ignimbrite is soft and zeolite-rich, has low permeability, high porosity and fewer macrofractures. The dyke intrusion promoted a narrow zone of welding, fracturing and perlitisation in the ignimbrite resulting in high permeability and focussed alteration. Our study shows how intrusions and their thermal aureoles create vertical pathways for, and horizontal barriers to, geothermal fluid flow.

Color effects of Cu nanoparticles in Cu-bearing plagioclase feldspars

Abstract The optical properties (scattering, absorption, and extinction) of spheroidal Cu particles embedded in intermediate plagioclase feldspar are computed for various sizes and shapes using the Mie theory and T-matrix method. The observed color for Cu-bearing plagioclase, as a function of particle size and shape, is also calculated from the computed extinction spectra. The colors and pleochroism observed in natural and treated Cu-bearing plagioclase can be explained from the computational results. The enigmatic green colors in some precious Oregon sunstones result from red light being scattered away by Cu nanoparticles of certain sizes. The UV-VIS spectra are collected on Cu-bearing plagioclase samples for comparison with the computational results, which are shown to match the optical observations. The results from this work may be used to quantify the concentration of colloidal Cu in plagioclase or glass with a similar refractive index. Particle sizes and shapes can also be characterized using extinction and scattering spectra, which can be collected with different optical configurations. New materials with special color effects and optical characteristics may be designed and engineered by applying the unusual properties of metal colloids.

Lead isotope geochemistry of plagioclase in the Skaergaard intrusion by LA-ICP-MS: Assessing the effects of crustal contamination and link with East Greenland flood basalts

The Skaergaard intrusion of East Greenland is one of the best studied layered intrusions on Earth and preserves an exceptional rock record produced during low-pressure, closed-system crystallization of Fe-rich tholeiitic magma. The lead isotope compositions of plagioclase feldspar in cumulates and related igneous rocks of the Skaergaard intrusion were determined directly from single spot analyses in thin section by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) (n = 757). Plagioclase primocrysts, typically with <2 ppm Pb, and feldspar in interstitial pockets from the Layered Series and from most of the Marginal Border Series have the same Pb isotope compositions within analytical uncertainty (208Pb/206Pb = 2.20 ± 0.06; 207Pb/206Pb = 0.889 ± 0.028). There are no significant Pb isotope differences between cores and rims of individual plagioclase primocrysts or between different types of interstitial pockets (e.g., interstitial granophyre, symplectites). These Pb isotope compositions are less radiogenic than those from most of the contemporaneous East Greenland flood basalts indicative of crustal contamination at deeper crustal levels prior to emplacement. Plagioclase from three samples of the Marginal Border Series adjacent to host gneisses (<5 m from the contact) have higher 208Pb/206Pb (2.30 ± 0.06, 2.35 ± 0.02, 2.51 ± 0.21) compared to the rest of the intrusion. These results confirm that crystallization of the Skaergaard intrusion occurred under essentially closed-system conditions with localized minor incorporation of “amphibolitic” gneiss. Hydrothermal alteration occurred at near-solidus to subsolidus conditions by circulating meteoric fluid that had equilibrated with the overlying flood basalts. This alteration resulted in albitized interstitial granophyre and rare spot analyses from plagioclase primocrysts characterized by Pb isotope compositions comparable to those of the flood basalts. Granophyres of different origins (e.g., transgressive granophyre, granophyric segregation) have variable Pb isotope compositions (208Pb/206Pb = 2.09–2.51; 207Pb/206Pb = 0.844–1.013) that are distinct from the Skaergaard cumulates. Based on Pb isotope systematics, combined with published SrNd isotopic compositions and 40Ar/39Ar geochronology from East Greenland and Faroe Island basalts, the Skaergaard intrusion is linked to eruption of the earliest of the Plateau Basalts in East Greenland (Milne Land Formation) during continental breakup and opening of the North Atlantic Ocean. This microanalytical study highlights the ability to conduct rapid Pb isotopic measurements in low-Pb concentration materials (e.g., <2 ppm Pb in plagioclase) at high spatial resolution by LA-ICP-MS with precision sufficient to constrain a range of magmatic processes in layered intrusions and other feldspar-bearing rocks preserved in the geological record.

Solar Wind Ion Sputtering of Sodium from Silicates Using Molecular Dynamics Calculations of Surface Binding Energies

Abstract For nearly 40 yr, studies of exosphere formation on airless bodies have been hindered by uncertainties in our understanding of the underlying ion collisional sputtering by the solar wind (SW). These ion impacts on airless bodies play an important role in altering their surface properties and surrounding environment. Much of the collisional sputtering data needed for exosphere studies come from binary collision approximation (BCA) sputtering models. These depend on the surface binding energy (SBE) for the atoms sputtered from the impacted material. However, the SBE is not reliably known for many materials important for planetary science, such as plagioclase feldspars and sodium pyroxenes. BCA models typically approximate the SBE using the cohesive energy for a monoelemental solid. We use molecular dynamics (MD) to provide the first accurate SBE data we are aware of for Na sputtered from the above silicate minerals, which are expected to be important for exospheric formation at Mercury and the Moon. The MD SBE values are ∼8 times larger than the Na monoelemental cohesive energy. This has a significant effect on the predicted SW ion sputtering yield and energy distribution of Na and the formation of the corresponding Na exosphere. We also find that the SBE is correlated with the coordination number of the Na atoms within the substrate and with the cohesive energy of the Na-bearing silicate. Our MD SBE results will enable more accurate BCA predictions for the SW ion sputtering contribution to the Na exosphere of Mercury and the Moon.

The Effect of Mineral Composition, Microstructure on Physical Properties of Aggregate from River Punjkora and Kunai, Dir (Lower), Khyber Pakhtunkhwa, Pakistan

Aggregate is a worldwide raw material used for various construction purposes which are obtained from geological material through drilling, blasting, mining, and river derived. This study has been focused on river Panjkora and Kunai-derived aggregates which are natural sources of aggregate used for various construction purposes in Dir (Lower). Field observation and detailed petrographic studies of representative samples reveal that rivers Panjkora and Kunai pass from different lithological units of granite, gabbroic, and amphibolite. Petrographically, the granitic rocks of the study area are consisting of alkali feldspar, quartz, and plagioclase feldspar. Minor accessory minerals in granite were hornblende, biotite, epidote, rutile, zircon, and ore minerals. The gabbroic rocks are consisting of pyroxene, plagioclase, and minor to accessory minerals including biotite, sphene, rutile, epidote, and ore minerals. The main mineral phases in amphibolites are hornblende, plagioclase, and a minor amount of quartz, sphene, and ore minerals. Gneissose fabric has developed in amphibolite refers to its banded nature. The minor mineral phases of amphibolite include epidote, ore minerals, and garnet. The feldspar alteration in granite is in the form of sericitization and normal zoning. The physical properties of river Panjkora and Kunai float i.e., water absorption, specific gravity, fine modulus, loss Angeles and soundness were within the range. Both petrographic and geotechnical properties suggested that these aggregates are suitable to be used as coarse aggregate in concrete. These must be present in the recommendation section at the end.

PETROGRAPHIC STUDIES AND PHYSICO-MECHANICAL PROPERTIES OF BIRIMIAN GRANITOIDS – A CASE STUDY OF OYOKO GRANITOIDS COMPLEX IN KOFORIDUA

The study investigated the physico-mechanical and petrographic properties of the basin-type granitoids of the Oyoko granitoid complex, to establish their strengths for engineering properties. The results obtained from this work will therefore be necessary in knowing the competences of the rocks for various engineering construction works. The purpose of this research is to determine the physico-mechanical and microstructural features of the granitoid suites of rocks at Oyoko. Thin sections were prepared and microscope used for the petrological studies of the rocks, whilst UCS test was conducted for the strength of the rocks. The Oyoko granitoid complex rocks were petrologically identified to be biotite gneisses, pegmatite and migmatite. The rocks at the study area have received little attention in mechanical and petrographic studies. These granitoid rocks have preserved porphyritic textures and consist of mineral assemblage such as biotite, quartz, plagioclase feldspar, alkali feldspar, amphibole, clino-pyroxene, chlorite, etc. The recrystallization of the plagioclase feldspar imply that these rocks have experienced some level of deformations. The foliated granitic gneisses intruded the older rock units, some of which had been subjected to earlier tectonism. The migmatite defines the area to be closer to a contact zone. The major structural features in the migmatite rocks were ptygmatic folds. The UCS value for the biotite gneiss of 91.6 N/mm2 gives a more representation of the general rock strength of the study area. The biotite gneisses at the study area may be classified to be mechanically strong and recommended for road construction and engineering works.

PETROGRAPHIC AND GEOCHEMICAL CONSTRAINTS ON TECTONIC SETTINGS OF THE BIRIMIAN SUPERGROUP VOLCANIC ROCKS, EVIDENCE FROM NEW DROBO ENVIRONS SOUTH OF JAMAN DISTRICT IN THE BONO REGION OF GHANA

The petrographic and geochemical studies of Birimian Supergroup meta-volcanic rocks in the New Drobo environs in Ghana help to decipher the tectonic settings at the study area. Twenty thin sections were prepared with rock samples from the field at the KNUST Geological Engineering Laboratory and petrographic microscope used to determine the different types of minerals in the samples and also the rock type. Whole rock geochemical analysis was done, using both X-Ray Fluorescence and Inductively Coupled Plasma Mass Spectrometer methods at Australian Laboratory Services in Canada. The main volcanic rock types at the study area comprise of basalt, andesite, dacite and rhyo-dacite with porphyritic mineralogical composition such as plagioclase feldspar, augite, olivine, hornblende, biotite, quartz, rutile, chlorite. The average concentrations of Zr &lt; 150 ppm, TiO2 &lt; 1.5 % and P2O5 &lt; 0.25 % and the ratios of Nb/Y &lt; 1.2 and Y/Nb &gt; 1 reveal the magma type in the study area to be continental tholeiitic basalt in nature. The mafic volcanic basalt is from a plate margin tectonic setting and thus of normal MORB and volcanic arc basalts. Also, the low basaltic values of the ratios of Ti/Y and Nb/Y confirm the tectonic setting of the area to be of plate margin. Zr is highly incompatible with respect to Ti and renders the ratio of Zr/TiO2 to be influenced by partial melting and causes heterogeneity in the mantle. The heterogeneity in the source of the mantle can be confirmed with the high value of the ratio of Zr/Y.

Geochemistry and mineral chemistry of pelitic gneiss of Ikare area, southwestern Nigeria

This study conducts Electron Probe Microanalysis (EPMA), X-ray Fluorescence (XRF) and Laser Ablation Inductively Coupled Plasma Spectrometry (LA-ICP-MS) analysis on the pelitic gneiss of the Basement complex of Nigeria. Phase equilibrium modeling was undertaken in the MnO–Na2O–CaO–K2O–FeO–MgO–Al2O3–SiO2–H2O–TiO2–O2 (MnNCKFMASHTO) chemical system using THERMOCALC. The rock comprises of sillimanite + biotite + garnet + K-feldspar + quartz + ilmenite + plagioclase ± cordierite. Garnet has inclusions of sillimanite, biotite, and quartz. There is a very close association between biotite and sillimanite. Fibrolitic and prismatic sillimanite are both present. Fibrolitic sillimanite surrounding biotite could have possibly formed through melt-residue back reactions involving crystallization of melt. Garnet has almandine higher than 60 % and pyrope less than 33 %. Plagioclase feldspar has anorthite content between 29 and 39 %, comprising of both oligoclase and andesine. Microtextures such as cordierite corona round garnet, symplectite and kinked biotite were observed. The textural association indicates that cordierite was formed at the expense of garnet and sillimanite; garnet + sillimanite + plagioclase => cordierite + melt/fluid. Metamorphic peak conditions of 770–840 °C and 5.5–7 kbar were obtained for the mineral assemblage garnet-biotite-sillimanite-K-feldspar-quartz indicating medium-pressure granulite facies metamorphism.

Microstructural analysis and characterization of lime mortar of seventeenth century Raigad hill fort from western India

The hill fort of Raigad is a massive historical structure constructed with basaltic stone blocks and cemented together with lime mortar. The lime mortar samples from the fort were examined using a petrological microscope, grain size distribution, X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope coupled with energy dispersive x-ray analysis (SEM–EDX). The mineralogical and compositional characteristic of the mortar was analyzed to provide a compatible repair mix for large scale restoration. Aggregates derived from weathering of basaltic rocks of Sahyadri hills were sourced from the vicinity of the fort. Non-hydraulic aerial lime of moderate porosity was specifically used in India's highly rain-fed Western Ghats for rapid evaporation of water and to prevent the build-up of salts. Thin section analysis and FTIR results indicate the use of organic proteinaceous material during the preparation of lime. FTIR analysis also showed the disorder in the man-made calcite crystals while XRD and SEM–EDX analysis elucidated the mixing of quartz and plagioclase feldspar derived from basaltic aggregates in the calcite matrix. The present study gives a holistic approach to prepare a compatible mortar for restoration.

Characterizing a weathering profile over the Kuantan Basalt

Three broad morphological zones can be differentiated; the top pedological soil (Zone I) being 3.60 m thick and comprising brown, soft to stiff, clays. The intermediate saprock (Zone II) is 1.12 m thick and consists of brown, very stiff, sandy silt with many lateritic concretions, whilst the bottom bedrock (Zone III) is an outcrop of vesicular olivine basalt with weathering along joints. Constant volume samples show the saprolite (sub-zone IC) to have dry unit weights of 11.78 to 12.80 kN/m3, whilst the solum (sub-zones IA and IB), and saprock, have values ranging from 10.65 to 11.09, and from 11.35 to 11.50, kN/m3, respectively. Porosities are variable; the saprolite with the lowest values of 52 to 56% and the solum and saprock with values of 57 to 60%. Clay and silt contents increase up the profile with a corresponding decrease in sand and gravel contents. Colloid (&lt;1 μm size) contents especially increase up the profile from 10 to 15% in saprock through 30 to 40% in saprolite and exceeding 57% in the solum, These increasing colloid contents point to the increasing effects of pedological processes. Thin-sections of weathered rims (1-2 cm thick) show alteration of basalt to start with formation of micro-cracks (Stage 1) that become stained by secondary iron oxides and hydroxides. Decomposition of the essential minerals then occurs in the order: olivine (Stage 2), augite (Stage 3), and plagioclase feldspar (Stage 4). An increase in apparent porosity, but a decrease in unit weights and specific gravity, reflect these stages of weathering; the boundary between ‘rock’ and ‘soil’ material occurring when all olivine and augite crystals have decomposed. It is concluded that the weathering profile results from in situ alteration of basalt due to lowering of an unconfined groundwater table; pedological processes giving rise to further alteration.

Study of Radioactivity in Bajaur Norite Exposed in the Himalayan Tectonic Zone of Northern Pakistan

Radioactivity in Granites of Pakistan systematically increases from south to north. The Ambella Granite found at the northern edge of Pakistan is highly radioactive. Radioactivity measurements made on, so called, Bajaur Granite, located in northern Pakistan, have been found to be lowest among all the granitic rock of the area. In order to find out the exact nature of Bajaur rocks, mineralogical studies were carried on rock chips and powdered samples. The Bajaur Norite contains plagioclase feldspar more than 45% as the chief constituent. Orthopyroxene and clinopyroxene are 27% and 18%. Quartz, biotite, and some opaque minerals are also found in accessory amounts. Bajaur Granite is in fact not a granite but Norite, which is rich in Na-Ca plagioclase series of feldspars. The plagioclase feldspar rich in Na-Ca are low in radioactivity. Moreover, the average gamma activities of 226Ra, 232Th, and 40K (4.98 ± 0.13 Bqkg −1, 4.03 ± 0.31 Bqkg −1, 204.40 ± 4.72 Bqkg −1 and a total of all three radionuclides are 214.00 ± 5.39 Bqkg −1) for Bajaur Norites are found too be much less than the average of the world’s Granites. Indoor and outdoor hazard indices of Bajaur Norite are much below building materials used throughout the world and largely beneath their criterion restrictions. As per radiations’ hazards are concerned, the Bajaur Norite as a building stone may be considered as the safest material available in the area that does not pose any radiological hazard.

Carbon Mineralization with North American PGM Mine Tailings—Characterization and Reactivity Analysis

Global efforts to combat climate change call for methods to capture and store CO2. Meanwhile, the global transition away from fossil energy will result in increased production of tailings (i.e., wastes) from the mining of nickel and platinum group metals (PGMs). Through carbon mineralization, CO2 can be permanently stored in calcium- and magnesium-bearing mine tailings. The Stillwater mine in Nye, Montana produces copper, nickel, and PGMs, along with 1 Mt of tailings each year. Stillwater tailings samples have been characterized, revealing that they contain a variety of mineral phases, most notably Ca-bearing plagioclase feldspar. Increases in inorganic carbon in the tailings and ion concentration in the tailings storage facilities suggest carbonation has taken place at ambient conditions over time within the tailings storage facilities. Two experiments were performed to simulate carbon mineralization at ambient temperature and pressure with elevated CO2 concentration (10% with N2), revealing that less than 1% of the silicate-bound calcium within the tailings is labile, or easily released from silicate structures at low-cost ambient conditions. The Stillwater tailings could be useful for developing strategies of waste management as production of nickel and PGM minerals increases during the global transition away from fossil energy, but further work is needed to develop a process that can realize their full carbon storage potential.

Raman study of shock effects in lunar anorthite from the Apollo missions

AbstractEarth’s moon is a primary exploration target for space agencies around the world. The Moon records and preserves key information about fundamental processes that shape planetary crusts such as impact cratering. Understanding shock effects in lunar anorthite (Ca‐rich endmember of plagioclase feldspar), the principal component of anorthosite and the most common crustal mineral on the Moon, is key to the early evolution of the Moon and terrestrial planets in the solar system. However, there has not been a systematic study of shock effects in lunar anorthite using modern analytical techniques that could be used in future lunar surface exploration, such as Raman spectroscopy. This study examined 23 polished thin sections from all six Apollo missions using optical and Raman spectroscopy. We documented a variety of shock features recording low to moderate shock levels, including fractures, deformed twins, undulatory extinction, planar features, and partially isotropic plagioclase. A notable nonobservation was the absence of planar deformation features (PDFs) or completely isotropic (i.e., diaplectic glass) in this suite of samples. Raman spectroscopy results of the observed shock features show similar progressive changes in terrestrial samples: As shock level increases, band broadening, reduction of intensities, and peak loss were observed. Our Raman data are efficient in identifying shock levels and distinguishing planar features from PDFs and deformed twins, and differentiating amorphous areas from crystalline plagioclase, suggesting Raman spectroscopy as a useful tool for purposely selecting moderately to strongly shocked samples to return in future lunar missions. Our study can also help the interpretation of Raman data of impact materials from the past and future exploration missions and demonstrate the utility of Raman spectroscopy for documenting and selecting samples for future lunar missions.