Mineral Fragments Research Articles

Shallow Moonquake Mechanisms Illuminated by Rheologic Characteristics of Basaltic Gouges

AbstractThe projected evolutionary history of the Moon and observed occurrence of moonquakes suggest that brittle faulting is present in the shallow lunar crust. The main component of the lunar crust, plagioclase, shows velocity‐strengthening behavior in the range of crustal temperatures. Chang'e 5 samples of lunar regolith show a mineral composition almost identical to basaltic bedrock. We measured the friction‐stability characteristics of dry synthetic gouges representative of basaltic faults assumed to be present in the lunar crust. Frictional strengths are ∼0.7 and exhibit an overall velocity‐strengthening response but transition to velocity‐weakening at intermediate temperatures (∼200–300°C) and stresses (∼25–100 MPa). Bounding temperature profiles representative of the lunar crust suggest that moonquakes are feasible in the lunar crust. The rheological heterogeneity of mineral fragments in basalt is a potential cause of unstable sliding on faults with the related steady‐state stress drop close to the minimum of the estimated dynamic stress drop. This suggests that some events with small stress drops are associated with the instability of mature basalt faults. However, observations of shallow moonquakes with high stress drop but merely moderate magnitude suggest that high degrees of healing on immature faults, small seismic nucleation lengths, or the failure of intact crust are present. We emphasize that moonquakes may arise from stress transfer and accumulation due to processes such as cooling contraction.

Pore structure evolution of organic-rich shale induced by structural deformation based on shale deformation experiments

The effect of structural deformation on shale pore structure is a key scientific problem in the development of shale gas resources in structurally complex areas. In this study, we investigated the evolution rules and mechanisms of pore structures in organic-rich shale subjected to structural deformation of varying mechanisms and intensities, by conducting whole-aperture pore structure characterization on experimentally deformed shale rather than naturally deformed shale. Results showed that brittle deformed samples developed more mesopores, macropores, and fracture pores. The inter-granular pores between mineral fragments and the inter-layer pores and micro-fractures were the primary sources of the increased pore structures. The ductile deformation of shale promoted large-aperture transitional pores, mesopores, and small-aperture macropores but was adverse to small-aperture transitional pores, large-aperture macropores, and fracture pores. The primary contributors to the enhanced pore structures were inter-granular pores and inter-layer micro-fractures formed during crumpled deformation and inter-layer sliding of clay minerals, and inter-granular pores caused by the grinding, rounding, and rotation of mineral fragments under the flow deformation of the shale matrix. The irreversible compression of organic matter pores, mineral-related pores, and pre-existing large-aperture pores and fractures was the main reason for the reduction in small-aperture transitional pores, large-aperture macropores, and fracture pores.

Snow survey within the copper ore deposits in the mining regions of the Urals

The paper presents the results of studies of dust residues of snow cover within various climatic zones and copper deposits of the Ural region. Snow cover research is one of the methods for environmental assessment of territories. This concerns the study of dust residues from snow cover samples, as shown by the example of the territories of the Northern and Southern Urals at different stages of work on copper deposits. The initial stage of study and development is considered using the example of porphyry copper deposits in the Chelyabinsk region, where snow samples reveal organic matter in dust residues, typical birch seeds, a small amount of minerals at a low dust load (P ˂ 100 kg/day per km2). For the deposits of the Ivdel region (Northern Urals), the dust residues largely contain organic dust, fragments of ore minerals (pyrite, chalcopyrite) and minerals of volcanic rocks and metasomatic rocks. The maximum value of the dust load is set for the Novo-Shemurskoye deposit currently being developed. A study of dust residues in the zone of influence of the Karabash copper smelter (before its reconstruction) has shown that in some parts of the sanitary protection zone the level of snow cover pollution is very high with dust load values up to 12,633 kg/day per km2, which is determined primarily by the widespread use of crushed copper smelting slag. In general, the study of dust residues of snow cover provides information about both the ecological state of the territories and the mineral composition of the residues, which must be used for practical purposes.

Petrological, chemical, and chronological study of breccias in the Chang'e‐5 soil

AbstractWe carried out a petrological, mineralogical, and geochemical study of fragmental and regolith breccia clasts separated from two Chang'e‐5 (CE‐5) soil samples, CE5C0000YJYX03501GP and CE5C0400, which provide an opportunity to investigate the compositional change of regolith at the landing site through time. Fragmental breccia CE‐5‐B3 contains a diverse range of basaltic clasts and basaltic mineral fragments, and some rare Mg‐suite‐like minerals. Regolith breccias CE‐5‐B006, CE‐5‐B007, CE‐5‐B010‐08, CE‐5‐B010‐09, CE‐5‐B011‐07, and CE‐5‐B016‐03 contain mare basaltic fragments, mare vitrophyric clasts, rare Mg‐rich fragments possibly derived from the Mg‐suite rocks, and impact‐derived glass spherules. Pb‐isotope data obtained for baddeleyite grains found both inside some of the basaltic clasts identified in breccia fragments and in the breccia matrices yield Pb/Pb dates similar to the 2 Ga crystallization age of the CE‐5 basalt fragments, extracted directly from the soil sample. Seventy‐four Pb isotope analyses of Ca‐phosphate grains also indicate that the majority of these grains have Pb/Pb dates of 2 Ga, suggesting that they originate from the CE‐5 basalts. In addition, a Pb–Pb isochron drawn through analyses of four Ca‐phosphates in breccia CE5‐B006 yielded an intercept corresponding to a date of 3871 ± 46 Ma, which is the best possible estimate of the formation age of these four grains. Electron probe microanalysis shows that the breccias contain components similar to CE‐5 mare basalt fragments extracted directly from the soil sample, implying that the fragmental and regolith breccia fragments are mostly composed of material sourced from the underlying basalts. The general absence of impact melt breccia clasts, along with the general lack of Fe–Ni metal and absence of added meteoritic debris all suggest that the regolith at the CE‐5 landing site is immature and dominated by material mixed together by small local impact cratering events. Trace element analyses show that the glass beads in the regolith breccias have a Th abundance of 4.06–5.28 μg g−1. This is similar to the Th content of the regolith above the Em4 unit at the landing site as measured from orbit, as well as the estimated bulk Th content of CE‐5 basalts, suggesting that Th of the local regolith is predominantly sourced from the underlying mare basalts, without significant Th addition from Th‐rich exotic clasts sourced from evolved lunar lithologies.

HED zircons as a window into the solar system’s first crust: Decoupling primordial differentiation, metamorphism and impact events through textural and chemical studies

The study of Howardite-Eucrite-Diogenite (HED) meteorites provides unique insights into early planet formation and the impact events that shaped the early Solar System. However, unraveling the complex history of the HED parent body (hypothesized to be the asteroid 4 Vesta) from whole-rock samples is challenging since most HEDs are impact-related breccias comprising mixed lithic and mineral fragments that experienced variable deformation and alteration. Combining U-Pb geochronology, trace element geochemistry, and microstructural analysis of zircon can unravel magmatic, metamorphic and impact processes through time to decipher the HED parent body evolution. Here we present textural (EBSD), geochronological (207Pb/206Pb SIMS dating) and geochemical data (Th/U, REE, Ti-in-zircon thermometry) on 61 zircon grains from melt breccia eucrites, unbrecciated/monomict/polymict eucrites, howardites and diogenites. Diverse textures indicate variable histories of impact deformation and high-temperature recrystallization. Undeformed, fractured zircons preserve primary zoning (CL, Th/U, REE) indicating magmatic and metamorphic origins. At least three magmatic zircon grains (Th/U > 0.3) give 207Pb/206Pb ages of 4558–4565 Ma, suggesting primary differentiation in the parent body first million years. Twenty metamorphic zircon grains (Th/U < 0.3) date to 4420–4568 Ma, indicating prolonged thermal metamorphism from impact heating and/or crustal cooling. Impact-recrystallized granular zircon grains reveal major impacts during and just after the parent body differentiation (4500–4560 Ma), plus later events potentially linked to synchronous impacts in the Solar System (e.g. the Moon). Similarity of metamorphic and shocked zircon ages (circa 4550–4450 Ma) suggests impacts occurred for ≥100 million years after the parent body formed.

Study on the formation of PM10 from high-sodium coal under gasification conditions in a flat-flame burner reactor

The deposition of fly ash is a key problem during utilization of high-sodium coal. A flat-flame burner reactor was used to investigate PM10 formation during high-sodium coal entrained flow gasification. The results showed that all particle size of PM10 at different gasification stages exhibits bimodal distributions. It transforms from irregular soot and char particles to square NaCl, spherical aluminosilicate and irregular char particles as gasification proceeds. As gasification time increases, Na and Cl in PM0.1 increases from 20.39 % to 57.61 %, Ca and Mg in PM0.1–1 increases from 22.51 % to 38.74 %, Si and Al in PM0.1–10 increases from 36.87 % to 71.60 %. Besides, a model is established to reveal the formation mechanism of PM10. It well-predicts the PM10 yields, and demonstrates that PM0.154, PM0.154–2.47, and PM2.47–10 come from the nucleation-collision-coagulation of vaporized Na and Cl etcetera, fragmentation of Ca, Mg-contained minerals, and fragmentation and gasification of char, respectively. The results provide valuable information for understanding of PM10 formation during high-sodium coal gasification.

The efficient applications of native flora for phytorestoration of mine tailings: a pan-global survey.

Mine tailings are the discarded materials resulting from mining processes after minerals have been extracted. They consist of leftover mineral fragments, excavated land masses, and disrupted ecosystems. The uncontrolled handling or discharge of tailings from abandoned mine lands (AMLs) poses a threat to the surrounding environment. Numerous untreated mine tailings have been abandoned globally, necessitating immediate reclamation and restoration efforts. The limited feasibility of conventional reclamation methods, such as cost and acceptability, presents challenges in reclaiming tailings around AMLs. This study focuses on phytorestoration as a sustainable method for treating mine tailings. Phytorestoration utilizes existing native plants on the mine sites while applying advanced principles of environmental biotechnology. These approaches can remediate toxic elements and simultaneously improve soil quality. The current study provides a global overview of phytorestoration methods, emphasizing the specifics of mine tailings and the research on native plant species to enhance restoration ecosystem services.

The Spectral Characteristics of Lunar Agglutinates: Visible–Near‐Infrared Spectroscopy of Apollo Soil Separates

AbstractThe lunar surface evolves over time due to space weathering, and the visible–near‐infrared spectra of more mature (i.e., heavily weathered) soils are lower in reflectance and steeper in spectral slope (i.e., darker and redder) than their immature counterparts. These spectral changes have traditionally been attributed to the space‐weathered rims of soil grains (and particularly nanophase iron therein). However, understudied thus far is the spectral role of agglutinates—the agglomerates of mineral and lithic fragments, nanophase iron, and glass that are formed by micrometeoroid impacts and are ubiquitous in mature lunar soils. We separated agglutinates and non‐agglutinates from six lunar soils of varying maturity and composition, primarily from the 125–250 μm size fraction, and measured their visible–near‐infrared reflectance spectra. For each soil, the agglutinate spectra are darker, redder, and have weaker absorption bands than the corresponding non‐agglutinate and unsorted soil spectra. Moreover, greater soil maturity corresponds to darker agglutinate spectra with weaker absorption bands. These findings suggest that agglutinates (rather than solely the space‐weathered rims) play an important role in both the darkening and reddening of mature soils—at least for the size fractions examined here. Comparisons with analog soils suggest that high nanophase iron abundance in agglutinates is likely responsible for their low reflectance and spectrally red slope. Additional studies of agglutinates are needed both to more comprehensively characterize their spectral properties (across size fractions and in mixing with non‐agglutinates) and to assess the relative roles of agglutinates and rims in weathering‐associated spectral changes.

The lithologic diversity of the Moon recorded in lunar meteorites Northwest Africa 7611 and 10480

AbstractNorthwest Africa (NWA) 7611/10480 are lunar regolith breccia meteorites, composed of mineral fragments and various clasts including mare basalts, volcanic glasses, gabbroic lithologies, and a diverse variety of highland materials (ferroan anorthosite, Mg‐suite, magnesian anorthosite, and alkali suite rocks) as well as different subvarieties of impact melt breccia. The Apollo two‐component mixing model calculation reveals that the NWA 7611 source region contains 58 wt% mare materials and 42 wt% highland components, but the estimated mare components in NWA 10480 have a higher abundance (66 wt%). The predominantly very low‐Ti (VLT) composition in both fine‐grained basaltic and coarse‐grained gabbroic lithologies indicates a provenance associated with a thick lava flow or a single magmatic system. The co‐occurrence of zoning patterns and fine‐scale exsolution lamellae in pyroxene debris supports a cryptomare deposit as the best candidate source. Phosphate Pb–Pb ages in matrix fragments, impact melt breccia, and basaltic clast indicate that the breccia NWA 7611 records geological events spanning approximately 4305–3769 Ma, which is consistent with the ages of ancient lunar VLT volcanism and the products of basin‐forming impacts on the lunar nearside. The youngest reset age at ~3.2 Ga is potentially related to the strong shock lithification process of breccia NWA 7611. Moreover, the similar petrology, texture, geochemistry, cosmic‐ray exposure data, and crystallization ages support that basaltic component in Yamato (Y)‐793274, and Queen Alexandra Range (QUE) 94281, NWA 4884, and NWA 7611 clan came from the same basalt flow.

Lunar Evolution in Light of the Chang'e-5 Returned Samples

The Chinese spacecraft Chang'e-5 (CE-5) landed on the northern Ocean Procellarum and returned 1,731 grams of regolith. The CE-5 regolith is composed mostly of fragments of basalt, impact glass, agglutinates, and mineral fragments. The basalts could be classified as of a low-Ti and highly fractionated type based on their TiO2 content of ∼5.3 wt% and Mg# of ∼28. Independent of petrographic texture, the CE-5 basalts have a uniform eruption age of 2,030 ± 4 Ma, demonstrating that the Moon remained volcanically active until at least ∼2.0 Ga. Although the CE-5 landing site lies within the so-called Procellarum KREEP [potassium (K), rare earth elements (REE), and phosphorus (P)] Terrane, neither the CE-5 basalts nor the mantle source regions of those basalts were enriched in KREEP components, such as incompatible elements, water, sulfur, or chlorine. Therefore, it would be a new and stimulating task in the future to look for the triggering mechanism of the young volcanism on the Moon. ▪The CE-5 spacecraft returned 1,731 grams of lunar regolith in December 2020. It was the first new lunar sample since the last collection in August 1976.▪CE-5 regolith is basaltic in chemical composition, with only ∼1% highland materials of anorthosite, Mg suite, alkali suite, and KREEP.▪The CE-5 basalt is low Ti and highly differentiated. It was extruded at ∼2.0 Ga, being the youngest lunar basalt identified so far from the Moon.▪The triggering mechanism of the ∼2.0 Ga lunar volcanism is not clearly understood because its mantle source was dry and contained low abundances of KREEP elements.

Provenance analyses of silted sediments in Shenzhen Bay: Insights based on rare earth elements and stable isotopes

Shenzhen Bay (SZB) in southern China is a typical eutrophic area, with internal pollution from its sediments representing an important nutrient source. However, the transport paths and sources of sediments in SZB remain unclear, making it difficult to analyze the nutritional budget and propose effective sediment management strategies. To address this, we linked a sediment fingerprinting technique to a Bayesian mixing model (MixSIAR) and conducted provenance analyses. We collected particle samples from SZB sediment and surrounding areas, including the Shenzhen River (SZR), Pearl River Estuary (PRE), and the northern South China Sea (SCS). Two groups of natural tracers were measured to trace different phases of sediments: (1) C and N parameters for the fates of the organic phase of sediments, and (2) rare earth element (REE) patterns for the provenance of mineral fragments. The results showed that the concentrations of total organic C and total N were 0.89–1.44 % and 0.05–0.13 %, respectively. MixSIAR suggested that fluvial inputs from SZR and PRE contributed 46.6 % and 30.3 % of organic matter, respectively. The organic matter in the PRE mainly originated from sewage and the upper reaches of the Pearl River. The concentration range of REEs in SZB sediments was 153.12–480.09 mg/kg with clear enrichment for light REE. MixSIAR results showed that the mineral fragments mainly originated from the outer bay (SCS and PRE, which contributed 57.2 % and 32.7 %, respectively). These results indicate that organic pollution follows a different path from the inorganic base, which is mainly related to anthropogenic input from land. This study highlights that complex sediment transport processes and pollution intrusions from the Pearl River are the issues that must be considered for eutrophication restoration in SZB.

Petrogenesis of Chang'E‐5 young mare low‐Ti basalts

AbstractThe regolith samples returned by the Chang'E‐5 mission (CE‐5) contain the youngest radiometrically dated mare basaltic clasts, which provide an opportunity to elucidate the magmatic activities on the Moon during the late Eratosthenian. In this study, detailed petrographic observations and comprehensive geochemical analyses were performed on the CE‐5 basaltic clasts. The major element concentrations in individual plagioclase grain of the CE‐5 basalts may vary slightly from core to rim, whereas pyroxene has clear chemical zonation. The crystallization sequence of the CE‐5 mare basalts was determined using petrographic and geochemical relations in the basaltic clasts. In addition, both fractional crystallization (FC) and assimilation and fractional crystallization models were applied to simulate the chemical evolution of melt equilibrated with plagioclase in CE‐5 basalts. Our results reveal that the melt had a TiO2 content of ~3 wt% and an Mg# of ~45 at the onset of plagioclase crystallization, suggesting a low‐Ti parental melt of the CE‐5 basalts. The relatively high FeO content (&gt;14.5 wt%) in melt equilibrated with plagioclase could have resulted in extensive crystallization of ilmenite, unlike in Apollo low‐Ti basalts. Furthermore, our calculations showed that the geochemical evolution of CE‐5 basaltic melt could not have occurred in a closed system. On the contrary, the CE‐5 basalts could have assimilated mineral, rock, and glass fragments that have higher concentrations of KREEP elements (potassium, rare earth elements, and phosphorus) in the regolith during magma flow on the Moon's surface. The presence of the KREEP signature in the CE‐5 basalts is consistent with literature remote sensing data obtained from the CE‐5 landing site. These KREEP‐bearing fragments could originate from KREEP basaltic melts that may have been emplaced at the landing site earlier than the CE‐5 basalts.

The Beacon Heights “Tinguaite” (Phonolite): A recrystallised agpaitic ignimbrite in the Mesoproterozoic Pilanesberg alkaline complex, South Africa

AbstractAn extrusive rock unit in the Mesoproterozoic Pilanesberg alkaline complex that has been referred to as the “Beacon Heights Tinguaite” since the work of Shand (1928) has been reexamined in the field and studied by petrographic microscopy, scanning electron microscopy, and whole-rock major and trace element analysis. The new observations indicate that the unit (here informally renamed the “Beacon Heights Phonolite” to comply with current petrographical nomenclature) is a laminated, volcanic rock in which mafic layers rich in sodic pyroxene alternate on any scale with discontinous, felsic layers consisting of alkali feldspar, nepheline, sodalite and their alteration products natrolite and analcime. Highly strontian apatite, fluorite, a manganiferous pectolite-group mineral, sphalerite and pyrrhotite are minor to accessory minerals. In addition, the rock carries indicator minerals typical of agpaitic rocks (including lamprophyllite and eudialyte-group minerals and their replacement products). The rock contains abundant crystal fragments of felsic minerals (alkali feldspar, nepheline and sodalite), fragments and elongated lenses of nepheline syenite, some of which contain primary magmatic lamprophyllite, and rare armoured lapilli. The overall structure of the rock is that of a welded ashflow tuff (igmimbrite) affected by post-magmatic recrystallisation processes. Whole-rock major and trace element compositions suggest a compositional affinity with members of the agpaitic, intrusive Green Foyaite Suite of the Pilanesberg Complex, and probably also a genetic relationship. The Beacon Heights Phonolite is a rare, possibly unique, example of an ashflow deposit of agpaitic, highly silica-undersaturated composition.

PETROLOGICAL and GEOCHEMICAL CHARACTERISATION of the KGWEBE VOLCANIC FORMATION in the ghanzi-chobe BELT PORTION of the KALAHARI COPPER BELT, western Botswana.

A combination of petrography and geochemistry was utilised to investigate the magma sources, magma evolution and petrogenesis of the Kgwebe Volcanic Formation (KVF) rock units. Based on their texture, the KVF rock units comprise amygdaloidal rocks, porphyritic mafic flows, pyroclastic rocks, porphyritic subvolcanic bodies, quartz-feldspar porphyries and clastic sedimentary rocks, that are intercalated with amygdaloidal rocks. The amygdaloidal rocks are commonly crosscut by calcite veins and characterised by amygdales (filled vesicles) set in the hyalopilitic groundmass. The porphyritic mafic flows are composed of plagioclase laths set in an aphanitic groundmass. The pyroclastic rocks are generally characterised by up to 75% of both mineral and lithic fragments originating from explosive volcanic activities. Porphyritic subvolcanic bodies are characterised by high content of subrounded epidote (after plagioclase) set in a microcrystalline groundmass. The quartz-feldspar porphyries are characterised by quartz and feldspar phenocrysts in variable proportions set in a fine-grained groundmass of variable colour. Rock units of the KVF represent two geochemically contrasting series that are not co-genetic and are derived from different geotectonic settings. The amygdaloidal rocks, porphyritic mafic flows, pyroclastic rocks and porphyritic subvolcanic bodies are sub-alkaline and basaltic in composition, whereas the quartz-feldspar porphyries span from the rhyolite/dacite (mostly) to the andesite/andesite basalt (accessorily) field compositions. Likewise, while quartz-feldspar porphyries are consistently high-K calc-alkaline bodies, their spatially associated amygdaloidal rocks, porphyritic mafic flows, pyroclastic rocks and porphyritic subvolcanic bodies counterparts are calc-alkaline. Similarly, quartz-feldspar porphyries are within plate bodies, whereas the more mafic KVF units are arc-related. Furthermore, the ferroan quartz-feldspar porphyries generated from the crust and the magnesian amygdaloidal rocks, porphyritic mafic flows, pyroclastic rocks and porphyritic subvolcanic bodies are mantle-derived, with however, significant crustal contamination fingerprints. Textural evidence (resorbed, embayed and rounded phenocrysts) and the inferred high-water content (as supported by the abundance of plagioclase phenocrysts) also suggest a rapid magma ascent and magma mingling occurred during the KVF eruption, which was both effusive and explosive. Concomitant volcanism and sedimentary processes likely occurred as supported by the intercalation of clastic sedimentary rocks within volcanics of the KVF.

Petrographic and Geochemical Inferences for Genesis of Terra Rossa: A Case Study from the Apulian Karst (Southern Italy)

Terra rossa is a reddish clay soil which is often present on the surface of limestone in regions with a Mediterranean-type climate. Its genesis is a controversial subject in terms of the origin of the parent material, from the residuum of underlying (carbonate/dolomite) bedrock in the absence/presence of an external silicate contribution (e.g., aeolian dust). Within this context the main goal of the present work was the understanding of the geochemical processes leading to the formation of the terra rossa starting from the carbonate bedrock. We report the results of a multi-method analysis on a terra rossa deposit occupying the bottom of a Quaternary karst depression on Mesozoic limestones exposed in the Murge area (Apulia Foreland, southern Italy). Geological, petrographic, textural, and chemical data were collected on karst products (reddish calcite incrustations and nodules, and fine-grained portion of terra rossa) by a detailed field mapping, optical microscopy, XRF and fusion ICP/MS analyses and by scanning electron microscope. New collected data show that the mineralogical composition of reddish incrustations and nodules is comparable, consisting of fibrous and impure calcite, detrital fragments of quartz, K-feldspar, zircon and authigenic minerals as (Mn, Ba, Ca) phases, (Al, Si, Mn, Fe, Mg, Ba, Ca) minerals, Fe-kaolinite and anatase. The prevailing minerals, instead, in the fine-grained portion of terra rossa are hematite, kaolinite, and goethite. Based on the chemical composition, and especially on REE patterns, a progressive interaction of silicate aqueous solutions (with Al, Si, Fe), containing pelite material, with the calcareous bedrock, as a source of carbonic acid, was the process driving the formation of terra rossa. Obtained results add new elements to the definition of the long-lasting question about the genetic processes responsible for the formation of terra rossa, corroborating their polygenetic origin, as result of limestone alteration in conjunction with the chemical interaction with allochthonous siliciclastic material.

Exotic mineral products from the Chupa gneisses of the Belomorides

Exotic mineral products (EМP) in the Chupa paragneisses of the Belomorian rock complex occur as an association of submicroscopic “spherules”, “pipes”, “chips” and their combined varieties. EМPs were derived by multi-stage allochemical stress-metamorphism of host gneisses at high pressure in temperature regimes typical of amphibolite (in the Late Archean) and epidote-amphibolite (in the Early Proterozoic) facies. One distinctive feature of EMPs is the presence of carbon in all of their mineral phases. The metal-like substance of “chips” and the cores of “spherules” and “pipes” is comparable in chemical composition and the Ме/С index (Ме = Fe + impurity elements) with known iron carbides, and is similar in composition to terrestrial minerals, such as chalypite, yarlongite, cohenite, and haxonite. The average bulk carbon content of core-free EMPs and core margin substance (at.%) is 7 for Archean and 7-11 for Proterozoic rocks. The average carbon content of iozite, a mineral phase prevalent in “spherules” and “pipes”, is 11 at.% for Archean and 14 at.% for Proterozoic units. The carbon content of the mineral fragments of host rocks (quartz, plagioclase, garnet, and kyanite), which form inclusions in EMPs, is 7-20 to 46 at. %. The distinctive characteristics of the EMPs, publications on the gas composition and soluble carbonaceous endogenic material of gas-liquid inclusions in the rock-forming minerals of Chupa gneisses, and the presence of graphite therein provide evidence for the significant, yet poorly understood contribution of carbon and its chemical compounds as fluid constituents to the highgrade metamorphism of the Belomorides.

The Early Cretaceous Tsagaangol formation sandstone provenance and paleoclimate

Early Cretaceous Tsagaangol formation refers to Zoolen terrain. This study attempts to make classification of the sandstones of the formation, define its sources and identify its alteration and paleoclimate condition. The sandstones of the formation are rich in mineral fragments, especially, quartz (comprising 70-75% of the entire content) and the composition is identified to be varying from subarcose to lithic arcose. As plotted on the source defining diagrams, they have been identified to be of continental block and mixed orogen and to get intensely altered or weathered under warm humid climate condition.

Subsolidus breakdown of armalcolite: Constraints on thermal effects during shock lithification of lunar regolith

Abstract Shock lithification of regolith breccias is a ubiquitous process on the surfaces of airless planetary bodies and may induce thermal effects, including melting on regolith breccia minerals. However, potential thermal effects on lithic and mineral clasts in regolith breccias have seldom been quantitatively constrained. Here, we report two types of micro-textures of armalcolite [(Mg,Fe2+)Ti2O5] in an Mg-suite lithic clast from lunar regolith breccia meteorite Northwest Africa 8182. One type of armalcolite contains oriented fine-grained ilmenite grains; the other occurs as an aggregate of ilmenite, rutile, spinel, and loveringite. We propose that the two types of micro-textures formed through subsolidus breakdown of armalcolite by different processes. The formation of ilmenite inclusions in armalcolite is related to slow cooling after the solidification of its source rock, whereas the ilmenite-rutile-spinel-loveringite aggregates probably formed during the shock lithification event of NWA 8182. The results indicate that the temperature at the margin of lithic clasts could be raised up to at least 600 °C during strong shock lithification of lunar regolith and has profound thermal effects on the mineralogical and isotopic behaviors of lithic and mineral fragments in lunar regolith breccias.

Effect of kaolinite additive on water-soluble sodium release and particle matter formation during Zhundong coal combustion

Zhundong coal causes serious slagging problems and particle matter (PM) pollution due to its high sodium content. In this paper, sodium release and PM formation experiments were carried out in tube and laboratory dropper furnaces using three types of coal in Zhundong. The effects of kaolinite additives on sodium release and PM formation, as well as the mechanism of different types of sodium release and PM formation, were investigated. The results showed that compared with water-soluble sodium, most organic sodium was released after a series of complex complexation reactions, such that kaolinite exhibited a better adsorption effect on water-soluble sodium. Furthermore, the concentration of different types of Na in PM emitted differed as a result of different coals, which would lead to different collision frequencies between particles and kaolinite. The PM2.5 stemmed from the homogeneous condensation of volatile elements and the fragmentation of minerals in the combustion, while the PM10 originated from the coalescence of the fine fragments of fly ash. Moreover, the kaolinite additive intensified the heterogeneous condensation reaction with gaseous sodium to form larger particles, due to the reaction effect of kaolinite for water-soluble sodium of PM2.5 being stronger than organic sodium and the organic sodium of PM10 being stronger than water-soluble sodium.

XENOLITHS OF POLYMICTIC BRECCIAS FROM KIMBERLITES OF THE YAKUTIAN DIAMONDIFEROUS PROVINCE

The polymictic breccias, extremely rare mantle conglomerates being the fragments of rocks and large mantle minerals cemented with fine-grained mass have been long provoking interest of petrologists worldwide. This work provides a comparative analysis of two xenoliths of polymictic rocks from kimberlite pipes of different age and productivity occurring in the Siberian craton. The similarity of the chemical composition of some minerals of polymictic breccias from kimberlites within different parts of the Siberian craton assumes possible formation of these minerals caused by the same factors in the prekimberlite period of these parts of the lithospheric mantle. A wide range of compositions and chaotic zoning of minerals, the presence of exsolution textures in orthopyroxene, ilmenite, sulfide, and kelyphite rims on garnet suggest that the fragments of the studied xenoliths are unbalanced. Sample SH18/20 is the first polymictic breccia showing asthenospheric melt-fluids sampling shallow depths of the spinel facies.