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The present overview answers the need of assessing the current state of the art concerning the application of principal components analysis (PCA) to Raman spectroscopy investigations of cultural heritage and related materials. An increment of the employment of this multivariate statistic technique to Raman results in the mentioned field began between 15 and 10 years ago, after a very slow start at the turn of the millennium. A delay of about a decade was observed with respect to PCA applied to elemental quantitative data of archaeometric analyses, likely a consequence of the required spectral pre‐treatment and to results of complex interpretation. Therefore, it is by now the time to summarize this evolution in a comprehensive, yet very specific way. In this overview, painting constituents were considered, both colouring materials and binders, in addition to natural and synthetic glasses, and biogenic and mineral gemmological materials. A marked unbalance between the studies pertaining to the different sections has been noticed, revealing a concentration of the work mainly on painting materials, including the study of ageing and alteration. The different aims of PCA application to Raman spectra, the various approaches and the achievable results, with the possible arising problems, were underlined, too. Special attention was given to the pre‐treatment of the spectra, which was observed to be essential to overcome the influence of several issues concerning bands intensity, spectral noise, background, fluorescence and so on. [ABSTRACT FROM AUTHOR]

In archaeometry, the correct assignment of archaeological artefacts with their original geological sources continues to be an indispensable tool for determining exploitation patterns, trade routes, tool production and the movement of goods in ancient times. Statistically, Mahalanobis distance has been an integral part of the artefact provenance methodology. However, this method presents disadvantages when some of the theoretical assumptions are not fulfilled. In this way and with a focus on the veracity of the correct assignment of archaeological samples to their geological sources, we present a technique that employs a semi‐supervised classification based on finite mixture models. This procedure uses labelled and unlabelled data to assign samples to groups with the advantage that it does not depend on the sample size of the groups as required by Mahalanobis distance. This procedure was first applied in a controlled experiment where the exact origin of the samples is known in order to verify the accuracy of the method; afterwards, it was applied to artefacts recovered from the archaeological site of Xalasco, Tlaxcala (Mexico), from both surface and excavation collections and analysed with a portable X‐ray fluorescence spectrometer. The resulting groups defined that the ancient dwellers of Xalasco exploited six supply sources located in Central Mexico. [ABSTRACT FROM AUTHOR]

This article presents the results of archaeological survey of ice patches in the vicinity of the vast obsidian quarries and artifact scatters found near Goat Mountain and the Kitsu Plateau in Mount Edziza Provincial Park, Tahltan Territory. During the survey, over 50 perishable artifacts were found, including stitched birch bark containers, wooden walking staffs, carved and beveled sticks, an atlatl dart foreshaft, and a stitched hide boot. Radiocarbon ages on 13 of the perishable artifacts reveal that they span the last 7000 years. These finds were made against a massive and stunning backdrop of scattered obsidian artifacts: bifaces, cores, flakes, and raw material nodules. This project collaborated with the Obsidian Discoveries Tahltan Tene Mehodihi Youth Group Hike and the "Our Ancestors' Trail" museum exhibition. This collaboration resulted in connections between the archaeological results presented here, community learning, and artistic inspiration. [ABSTRACT FROM AUTHOR]

We investigated Late Permian Li-rich claystones with up to 1.05 wt% Li2O (average: 0.45 wt% Li2O) in the Pingguo area in Guangxi, southwest China. Our results show that cookeite (chlorite group) is the dominant Li-bearing mineral. Cookeite is intercalated with authigenic illite and detrital kaolinite, which suggests that cookeite formed during burial diagenesis from pre-existing Li-rich kaolinite in the original clay assemblage. The Li-rich claystones were mainly sourced from felsic volcanic rocks of the Emeishan large igneous province (LIP), and the Li-rich kaolinite was likely produced by weathering of felsic volcanic materials (i.e., pyroclastic rocks, tephras, and volcanic glass) deposited on a Permian carbonate platform. We propose that the abundance of precursor kaolinite and its Li content control the degree of Li enrichment in this new potential Li resource. [ABSTRACT FROM AUTHOR]

Copyright of Mexicon is the property of Verlag Anton Saurwein and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The rising concern for the environment and the need for a sustainable economic model has stimulated experimentation in the field of construction materials, notably in replacing certain components from cementitious materials with construction and demolition waste. The main objective of this study is to replace a significant proportion of natural aggregates with glass waste, in the composition of plastering mortars, and to observe the evolution of physical–mechanical characteristics in the fresh state: apparent density, consistency, and segregation tendency, and in the hardened state: apparent density, flexural strength, compression strength, and adhesion to the substrate, across time, at 3, 7, 14, and 28 days. SEM and EDX tests were also performed to observe the microscopical characteristics. The experimental program studied four types of plastering mortars: the reference mortar—CS IV, and three mortars in which aggregates have been replaced with glass waste in the following proportions, by mass: 15%, 30%, and 45%. Results obtained on fresh properties (apparent density and consistency) indicate a decrease in values as the percentage of glass increases, with the exception of the mortar with 30% aggregated glass replacement. The flexural strength and the compressive strength were improved by replacing 30% of the aggregates with glass waste and were not significantly impacted by a replacement of 15%. Mechanical properties decreased at a replacement level of 45%. All glass aggregate mortars had lower adhesion strength to the brick substrate than the reference mortar by up to 70%. SEM and EDX analyses showed the morphology of the studied mortars and the processes taking place to increase mechanical strength. Further research directions are proposed, including studying the glass particles, the occurrence of alkali–silica reactions, durability, and improvement of adhesion to the substrate, for progressing towards the most viable, locally sourced, waste-containing plastering mortar. [ABSTRACT FROM AUTHOR]

This research investigated the physicochemical properties and pozzolanic reactivity of mechanochemically and thermally treated clay, marl, and obsidian as supplementary cementitious materials (SCMs). The results suggest that the mechanochemical treatment of clay and marl resulted in delamination, dehydroxylation, and amorphisation of the mineral components (including calcite); while for obsidian, the main effect was particle size reduction. Among all samples prepared, the mechanochemically treated obsidian exhibited the best performance as a SCM and achieved marginally higher strength performance at 20% cement replacement compared with the CEM I cement mortar (with on SCM). The thermally activated clay and marl exhibited highest pozzolanic reactivity than the mechanochemically treated counterparts owning to the formation of free lime from calcination of calcite. However, the mechanochemically treated clay and marl were still able to achieve over 80% of the strength activity index and performed much better than the untreated materials. These results indicate that mechanochemical treatment can effectively improve the pozzolanic reactivity of clay minerals that contain calcite up to 68% without directly emitting process CO2 to the environment (calcination of carbonates), which can be an alternative activation route to the high-temperature calcination-treatment method. [ABSTRACT FROM AUTHOR]

This study aimed to ascertain the alterations in aging responses of fiber‐reinforced composites, as well as the effects of their natural particle reinforcement, through exposure to acidic and alkaline solutions. Specimens were produced with 0 wt. % (neat), 1 wt. %, 2 wt. % and 3 wt. % particle ratios from acorn and pinecone particles. A particle content of 2 wt. % was determined to yield the best mechanical properties in all mechanical tests conducted for pinecone reinforcement. The highest improvement in strength, observed in 3 wt. % pinecone‐reinforced composites, reached 22.5% at flexural strength. HCl and NaOH diluted in water were chosen as aging solutions. Mechanical tests were repeated at different stages of aging. According to the findings, 1 wt. % particle‐reinforced composites showed better resilience to the mechanical property reduction effect of aging compared to the 2 wt. % and 3 wt. % particle‐reinforced composites. At a particle ratio of 2 wt. %, the acorn‐reinforced specimens exhibit their highest maximum penetration force, which is 5% higher than that of the 0 wt. % composite, consistent with the results of tensile and compressive tests. Highlights: Composite material was manufactured by hand lay‐up and vacuum bagging method.Specimens were aged using acid and base solutions.Tensile, compressive, and bending results were obtained depending on particle type and ratio.Tensile, compressive, and bending strengths of composites were compared according to various aging times. [ABSTRACT FROM AUTHOR]

Ian McDougall was a renowned Earth scientist who gained worldwide distinction for his research in the fields of K-Ar and 40Ar/39Ar geochronology. He was born in Hobart, Tasmania and obtained a BSc (Hons) at the University of Tasmania and a PhD at the Australian National University in Canberra. Following his PhD, he was introduced to the emerging field of K-Ar geochronology during a postdoctoral year at the University of Berkeley in 1961. On his return to Australia, Ian accepted a position in the newly established K-Ar laboratory at the Australian National University. He pioneered the application of the K-Ar dating method to young volcanic rocks and played a pivotal role in developing the geomagnetic timescale. These findings provided crucial evidence in support of the 'hot spot' (mantle plume) model and the emerging theory of plate tectonics. He subsequently established the 40Ar/39Ar geochronology method at the Australian National University and gained an international reputation for meticulous experimental work. In the 1980s, he resolved a significant controversy with regard to the age of hominin fossils and artefacts in the Turkana Basin, Kenya. Over the following four decades, he developed a comprehensive geochronological framework for volcanism across the Turkana Basin, providing the basis for current interpretations of early human evolution in the region. Other notable collaborative accomplishments include the application of the 40Ar/39Ar method to thermal history studies and noble gas geochemistry studies of volcanic glasses and mantle material, which provided insights into the evolution of Earth's atmosphere and interior. Ian's scientific contributions were recognised with numerous honours and awards, including being elected a Fellow of the American Geophysical Union, a Fellow of the Australian Academy of Science, and receiving the Jaeger Medal from the Australian Academy of Science and the Centenary Medal for 'service to Australian society and science in geochronology'. Ian McDougall was an internationally renowned Earth scientist who spent most of his academic career at the Australian National University. This memoir outlines his research achievements in the fields of K-Ar and 40Ar/39Ar geochronology, from his pioneering work on young volcanics that supported the emerging theory of plate tectonics, to the establishment of a comprehensive geochronological framework for hominin evolution in eastern Africa. Photograph by Warren Hudson, ANU Photographic Services. [ABSTRACT FROM AUTHOR]

An anisotropic GIS distance model based on slope and travel time is tested to evaluate travel costs in environments with steep topographies (Lucero et al. 2021). The proposed ranges (local, non-local and extra-regional) are applied to evaluate supply costs and changes in access to obsidian sources: Arroyo Paramillos and Laguna del Diamante. The distribution of artifacts with geochemical analyzes assigned to these sources is evaluated; annual/seasonal availability of the sites from a snow cover analysis with GIS has also been considered. The decrease in obsidian follows the expected trends according to the decrease in sources, although it is asymmetric on both slopes of the Andes. Unexpected spatial trends can be explained by the location of sites at variable thresholds of seasonality and access depending on environmental changes, but also by social changes associated with the territorializing of space. [ABSTRACT FROM AUTHOR]

Perlite is a volcanic glass that, under thermal treatment, expands, producing a highly porous and lightweight granular material which finds application in the construction, horticulture, insulation and other industrial sectors. Proper control of the feed properties and the expansion conditions allows the production of purpose-oriented grades, while the primary evaluation of its appropriateness for use in each sector is performed by the proper characterization of relevant physical, thermal or/and mechanical properties. However, due to its extreme fineness, low density, and friability, most of the available characterization methods either fail in testing or provide erroneous results, while for certain properties of interest, a method is still missing. As a consequence, the way towards the evaluation of the material is rife with uncertainties, while a well-defined methodology for the characterization of the critical properties is of practical importance towards the establishment of a pathway for its proper analysis and assessment. This article presents the available methodology for determining the main properties of interest, i.e., the size and density, water repellency/absorption and oil absorption, the microstructural composition, crushing and abrasion resistance and isostatic crushing strength, and also sampling and size reduction processes. The issues raised by the application of existing methods are analyzed and discussed, ending up to a proper methodology for the characterization of each property, based on the long-term experience of the Perlite Institute. The study is supplemented by updated insights on ore genesis, physicochemical properties, mineralogical composition and the expansion mechanism, as background information for the sufficient comprehension of the nature and properties of perlite. [ABSTRACT FROM AUTHOR]

Surveys carried out in the Javakheti Plateau during the last decade have improved our knowledge of the Bronze Age archaeology of this highland zone of the Lesser Caucasus of Georgia. Surveys have been conducted all over the area surrounding the Mt. Chikiani volcano, along the southern terraces of the Tsalka Reservoir, and some of the north-western slopes of Mt. Paravani. All these territories have yielded impressive evidence of megalithic monuments, stone-walled villages, kurgans , basalt and schist quarries, as well as obsidian extraction and production areas. Among these latter is an important circular platform made of basalt boulders, above which a workshop for the manufacture of obsidian bifacial arrowheads and spearheads was discovered. All the aforementioned features have been GPS-recorded and photographed with the use of a non-professional small drone. They show that the entire region is a monumental landscape, which most probably started to be built around the beginning of the Bronze Age, as many of the lithic finds would suggest. [ABSTRACT FROM AUTHOR]

Copyright of Intersecciones en Antropología is the property of Universidad Nacional del Centro de la Provincia de Buenos Aires, Facultad de Ciencias Sociales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nontuberculous mycobacteria (NTM) are environmentally acquired opportunistic pathogens that can cause chronic lung disease. Within the U.S., Hawai'i shows the highest prevalence rates of NTM lung infections. Here, we investigated a potential role for active volcanism at the Kīlauea Volcano located on Hawai'i Island in promoting NTM growth and diversity. We recovered NTM that are known to cause lung disease from plumbing biofilms and soils collected from the Kīlauea environment. We also discovered viable Mycobacterium avium, Mycobacterium abscessus, and Mycobacterium intracellulare subsp. chimaera on volcanic ash collected during the 2018 Kīlauea eruption. Analysis of soil samples showed that NTM prevalence is positively associated with bulk content of phosphorus, sulfur, and total organic carbon. In growth assays, we showed that phosphorus utilization is essential for proliferation of Kīlauea‐derived NTM, and demonstrate that NTM cultured with volcanic ash adhere to ash surfaces and remain viable. Ambient dust collected on O'ahu concurrent with the 2018 eruption contained abundant fresh volcanic glass, suggestive of inter‐island ash transport. Phylogenomic analyses using whole genome sequencing revealed that Kīlauea‐derived NTM are genetically similar to respiratory isolates identified on other Hawaiian Islands. Consequently, we posit that volcanic eruptions could redistribute environmental microorganisms over large scales. While additional studies are needed to confirm a direct role of ash in NTM dispersal, our results suggest that volcanic particulates harbor and can redistribute NTM and should therefore be studied as a fomite for these burgeoning, environmentally acquired respiratory infections. Plain Language Summary: Nontuberculous mycobacteria (NTM) can cause environmentally acquired lung infections in susceptible individuals. While NTM infections are linked to household exposures, there are likely non‐household routes of acquisition. Hawai'i is a geographic hotspot for NTM lung disease, but the island‐specific environmental niches for NTM remain poorly understood. Thus, a greater knowledge of where susceptible individuals acquire their infections is an important public health endeavor that may lead to actions to mitigate potential sources of NTM exposures. In the current work, we show that particulate matter collected from Kīlauea Volcano on Hawai'i Island harbors Mycobacterium avium, Mycobacterium abscessus, and Mycobacterium intracellulare subsp. chimaera. Microbiologic, environmental, and NTM genetic data demonstrate that volcanic ash may act as a novel vehicle for the dispersal of clinically relevant NTM. Key Points: Long‐range transport of hitch‐hiking infectious agents has never been reported for volcanic eruptions globallyAsh recovered from the 2018 Kīlauea Volcano eruption harbors species of nontuberculous mycobacteria (NTM) known to cause lung diseaseGenomic evaluation reveals Kīlauea‐derived NTM are genetically similar to respiratory isolates identified on other Hawaiian Islands [ABSTRACT FROM AUTHOR]

Critical to the survival of island-based human societies is their resilience and adaptation to volcanic hazards. We here evaluate pre-Hispanic (before 15th century AD) land use patterns on the volcanic island of Tenerife, Canary Islands, Spain using obsidian hydration dating (OHD). The samples studied include archaeological artifacts and natural rock chips from multiple sites of different elevation and micro-climate settings. We systematically collected samples from the southern dry area around Barranco de las Monjas in the Bandas del Sur. These include a total of 28 isolated artifact scatters (here, a scatter is defined as a minimum spatial unit of artifacts distributed spatially limited range on the surveyed surface), one dwelling, and several pyroclastic deposits containing obsidian clasts. We also collected several artifacts adjacent to a large obsidian flow of Tabonal Negro in the Las Cañadas Caldera. Unsystematic surveys in north of Mt. Teide identified large obsidian outcrops located at Tabonal de los Guanches and Charco del Viento. Size differences among surface-derived obsidian artifacts (i.e., Bandas del Sur, Las Cañadas Caldera, Icod Valley) suggest that pre-Hispanic groups utilized obsidian from multiple outcrops over wide areas. Hydration analysis on 136 obsidian flakes collected from both surface and buried contexts showed only minor obsidian hydration rims (5% of total samples) and varied mean rim thicknesses (0.6–3.5μ). The low percentage of hydration rim formation may be caused by environmental factors such as wind erosion, thermal effects from volcanic or natural ground fires, or due to obsidian geochemistry (low SiO 2 and water content of phonolitic obsidian). Surface-collected obsidian flakes from the southern dry area do contain hydration rims along internal fissure. The estimated hydration rates from these samples can provide an approximate age when compared to buried obsidian artifacts with associated radiocarbon dates. [ABSTRACT FROM AUTHOR]

Data from our original database, which includes more than 2 600 000 analyses for 75 elements of mineral-hosted melt inclusions and quench glasses in volcanic rocks, are generalized to calculate the mean concentrations of major, volatile, ore, and trace elements in magmatic melts from the following dominant geodynamic environments: (I) spreading zones of oceanic plates (mid-oceanic ridges), (II) environments affected by mantle plumes in oceanic plates (oceanic islands and lava plateaus), (III, IV) environments related to subduction processes (III is zones of arc magmatism on the oceanic crust, and IV is zones of magmatism in active continental margins in which magma-generating processes involve the continental crust), (V) environments of continental rifts and areas with continental hotspots, and (VI) environments of backarc spreading. A histogram of SiO2 distribution in natural magmatic melts shows a bimodal distribution: one of the maxima falls onto SiO2 concentrations of 50–52 wt % and the other onto 72–76 wt %. The most widely spread melts contain 62–66 wt % SiO2. Mean temperatures and pressures are calculated for each of the environments. The normalized multielemental patterns presented for environments I through VI show the ratios of the mean concentrations of elements in magmatic melts of mafic, intermediate, and felsic composition to the concentrations in the primitive mantle. Mean ratios of incompatible, trace, and volatile components (H2O/Ce, K2O/Cl, Nb/U, Ba/Rb, Ce/Pb, etc.) are evaluated for the melts of each of the environments. The variations in these ratios are calculated, and it is demonstrated that the ratios of incompatible elements are mostly statistically significantly different in the different environments. The differences are particularly significant between the ratios of the most differently incompatible elements (e.g., Nb/Yb) and some ratios involving volatile components (e.g., K2O/H2O). [ABSTRACT FROM AUTHOR]

We present the first record of obsidian from the Meliquina (MQ) geochemical group at Bahía Coique, Los Ríos Region, Chile. This case extends to three the geochemical groups recovered in archaeological contexts and identified by non-destructive techniques, circulating in both slopes of the Andes Mountains, between northern Patagonia and Araucania. [ABSTRACT FROM AUTHOR]

Here we analyze the acquisition and distribution of Yuco obsidian in northern Patagonia, as well as what differentiates it from other obsidian types in the region, particularly near the numerous mountain lakes. The recovery of Yuco obsidian 260 km south of the source, yet absent in intermediate areas such as Traful and Nahuel Huapi, as well as west of the Andes, causes us to reflect on the nature of late human occupation of Patagonian forests. At the same time, we criticize the limitations of analytical techniques used to identify geochemical obsidian groups over the last three decades. In particular, we discuss the implications between destructive and non-destructive analytical methods. [ABSTRACT FROM AUTHOR]

The natural and synthetic fibers are combined in a single composite to achieve a balance between the desired strength and cost considerations. In this study, the vacuum resin transfer moulding process was used to prepare an epoxy‐based composite. The composite consisted of grewia optiva as the natural fiber and glass fiber as the synthetic fiber, both with a fixed weightage of 10 %. Dolomite was used as a filler with varying content (0 %, 5 %, 10 %, and 15 weight %). The physical, mechanical, erosion wear and morphological behavior of the epoxy‐based composite were investigated. The inclusion of dolomite filler significantly increased the composite hardness and impact strength but reduced its tensile and flexural strength. At a dolomite filler content of 10 weight %, the erosive wear was reduced, while it increased at higher dolomite filler contents. The composite was examined using the L16 array, and the minimum wear rate was observed at an impingement angle of 30°, a velocity of 10 m/s, and an erodent size of 150 μm. Morphological studies were conducted to explore the possible mechanism for the variation in erosive wear at different dolomite contents in the hybrid composites. [ABSTRACT FROM AUTHOR]

Portable X‐ray fluorescence (pXRF) geochemical analysis on obsidian from five Formative period (1200 BCE to AC 100) sites from Tlaxcala, Mexico, has revealed that most of the material had similar values to those found in the closest obsidian source, named El Paredón, Puebla. Nevertheless, initial analyses did not resolve whether these materials came from the same caldera or from a specific obsidian deposit. Here we present a methodology that allows the identification of obsidian subsources. The results reveal that Tlaxcalan populations took advantage of a specific obsidian deposit called Tres Cabezas, Puebla, providing valuable new data to identify associated regional exchange networks. [ABSTRACT FROM AUTHOR]

The Gallinas Mountains of west-central New Mexico were home to agriculturalists between ca. a.d. 850 and 1450. Ongoing research of the Lion Mountain Archaeology Project (LMAP) has allowed for in-field analysis of surface obsidian artifacts via portable handheld energy dispersive X-ray fluorescence spectrometry (ED-XRF). Influenced by principles of preservation archaeology and the archaeological repository curation crisis, the LMAP has sought to design and conduct field research to gather the most data with the least amount of impact to sites. Non-destructive in-field analysis via portable handheld ED-XRF subscribes to these goals while also providing answers to significant questions about human behavior. Results show that variable patterns of obsidian source utilization and procurement strategies existed both through time and between contemporaneous populations. These results are indicative of a shifting system of exchange and social interaction between residents of the region and surrounding areas during the Ancestral Pueblo occupation of the area. [ABSTRACT FROM AUTHOR]

By employing kinetic interface sensitive (KIS) tracers, we investigate three different types of glass‐bead materials and three natural porous media systems to quantitatively characterize the influence of the porous‐medium grain‐, pore‐size and texture on the specific capillary‐associated interfacial area (FIFA) between an organic liquid and water. By interpreting the breakthrough curves (BTCs) of the reaction product of the KIS tracer hydrolysis, we obtain a relation for the specific IFA and wetting phase saturation. The immiscible displacement process coupled with the reactive tracer transport across the fluid–fluid interface is simulated with a Darcy‐scale numerical model. Linear relations between the specific capillary‐associated FIFA and the inverse mean grain diameter can be established for measurements with glass beads and natural soils. We find that the grain size has minimal effect on the capillary‐associated FIFA for unconsolidated porous media formed by glass beads. Conversely, for unconsolidated porous media formed by natural soils, the capillary‐associated FIFA linearly increases with the inverse mean grain diameter, and it is much larger than that from glass beads. This indicates that the surface roughness and the irregular shape of the grains can cause the capillary‐associated FIFA to increase. The results are also compared with the data collected from literature, measured with high resolution microtomography and partitioning tracer methods. Our study considerably expands the applicability range of the KIS tracers and enhances the confidence in the robustness of the method. Key Points: The capillary‐associated interfacial area is measured with the kinetic interface sensitive tracer method in six unconsolidated porous mediaIt is found the maximum specific capillary‐associated interfacial area is linearly correlated to the inverse mean grain diametersThe higher capillary‐associated interfacial area is found in natural porous media due to surface roughness and irregular grain shapes [ABSTRACT FROM AUTHOR]

Fault rock petrology exerts an important influence on the permeability structure and mechanical properties of fault zones. Slip‐related deformation on upper‐crustal faults in basaltic rocks is closely associated with fluid‐rock interaction, altering the distribution of physical properties within the fault. Here, we present quantitative descriptions of the geochemical and petrological evolution of basalt‐derived fault rocks from three passively exhumed fault zones in the Faroe Islands. Fault‐rock petrology is determined by optical petrography and automated phase identification based on micrometer‐scale chemical maps from scanning electron microscope X‐ray spectroscopy. Geochemical evolution is assessed from major and trace element composition measured by X‐ray fluorescence. The fault rocks show intense fluid‐mediated alteration from a tholeiitic basalt protolith in the damage zones, and mechanical mixing in the fault cores. Pervasive alteration occurs early during fault zone evolution, with incipient fault damage increasing permeability and allowing along‐fault percolation of carbonated meteoric water, increasing fluid‐rock ratios. Our results suggest that the only mobile species within the fault zones are Ca, Si, and Al, which are leached during the hydrolysis of volcanic glass and plagioclase, and CO2, which is added by percolating waters. These species are transported from the damage zones into the fault cores, where they precipitate as zeolite and calcite cement in veins and hydrothermal breccias. We propose that solutes are replenished by cement dissolution through pressure‐solution during cataclastic creep, during repeated cycles of hydrofracture and cementation. The fault zones are natural reactors for fluid‐mediated alteration by CO2 and water, while other species are redistributed within the fault zones. Key Points: Basalt‐hosted fault petrology records progressive stages of fluid‐rock alteration followed by dissolution‐precipitation cycles of cementThe main mobile elements are Ca, Si, Al, and CO2, which are largely reprecipitated as Ca‐zeolites and calcite within the fault zoneAlternating calcite–zeolite mineralization highlights carbonate activity and metal cation availability feedback during fluid‐rock reaction [ABSTRACT FROM AUTHOR]

Copyright of Black Sea / Karadeniz is the property of Black Sea / Karadeniz and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a glassy borosilicate compound was synthesized using recycled glass and natural clays. Even though glass recycling is the generally accepted standard practice for managing glass waste, fine fractions of container soda-lime glass or cullet of other compositions are still disposed of in landfills. Thus, advanced upcycled products that offer greater economic motivation for implementation in industry may be the key to success, but these are frequently linked to alternative methods of product synthesis. Here, a simple and facile route of borosilicate compound production has been synthesized and characterized. The physicochemical characterization of the compounds was carried out to determine their properties and the antibacterial efficacy of the synthesized compound against Escherichia coli (E. coli) was investigated. The structural and spectroscopic characteristics were identified as a compound that conformed to quartz, cristobalite, and silicon hexaboride (SiB6). For the antibacterial activity, two test types were typically performed; in the first one, the dilutions of the grind were combined with chloramphenicol at a concentration of 20 µg/mL to perform a synergistic action against the bacteria and in the second one, only the amorphous borosilicate compound was tested against E. coli ATCC 25922 strains. The treatments applied considered the dilutions from 8 to 40 µg/mL. The minimum inhibitory concentration (MIC) sensitivity tests began with incubation at 37 °C in the tubes and subsequent seeding in Petri dishes for colony-forming unit (CFU) counting. The results obtained indicated that the samples possessed a productive antibacterial effect, which support their use in various biomedical applications. [ABSTRACT FROM AUTHOR]

The article discusses the uplift of the Puna Plateau in northwestern Argentina and challenges previous interpretations of its geological history. The authors argue that the field observations and paleoaltimetry analysis used to support significant deformation and uplift in the Miocene are flawed. They suggest that the interpretation of deformation in the Eastern Cordillera does not necessarily require synchronous deformation in the Puna Plateau. The authors emphasize the need for a comprehensive approach that considers all available data and acknowledges uncertainties in order to understand the complex uplift and paleoenvironmental history of the region. [Extracted from the article]

Drilled cores of Macusani green obsidian pebbles from Peru were hydrated and melted above their liquidus temperatures at 200 MPa to a single column ~4 cm in length and then undercooled in a thermal gradient >150 °C along the length of the cores. Despite thousands of hours at subliquidus temperatures, the crystallinity of the products ranged from ~30 to ~5 vol%. Mineral assemblages varied along the length of the cores but not in relation to the thermal gradients in all cases. Oscillations in the abundances of plagioclase, K-feldspar, and quartz were observed across the crystallization fronts and along the lengths of the cores. The originally homogeneous melts became heterogeneous in response to crystallization and to thermal gradients. Chemical gradients in the glasses included sharp boundary layer pile-up of F and B adjacent to the crystallization fronts, as well as linear gradients among several of the elements spanning the entire lengths of the melt columns. Values of molar K/(K+Na) in the glasses, plotted as K*, varied positively with Si, inversely with Al and F, and positively with the domains of K-feldspar that formed at maximum distance from the plagioclase-rich regions. Overall, the results are marked by sharply bounded textural domains, by the spatial segregation of mineral assemblages, by oscillations in mineral assemblages at multiple scales, and by monomineralic crystal aggregates that are hallmarks of pegmatite bodies. Temperatures recorded by feldspars closely approached the actual temperature gradient down to ~500 °C, and the solvus on the alkali feldspar join has been delineated for the first time by the simultaneous crystallization of feldspars from an undercooled melt. [ABSTRACT FROM AUTHOR]

We present stable hydrogen-isotope analyses of volcanic glass (δ Dg) and radiometric ages (U-Pb zircon, U-Th calcite, AMS14C) from deformed sedimentary deposits in the vicinity of the intermontane Pocitos Basin in the central Puna of the Andean Plateau at about 24.5°S. Our results demonstrate 2-km surface uplift since the middle to late Miocene and protracted shortening that persists until the present day, while other sectors of the Puna show evidence for tectonically neutral and/or extensional settings. These findings are at odds with previous studies suggesting near-modern elevations (4 km) of the Puna Plateau since the late Eocene and formation of the intermontane Miocene Arizaro-Pocitos Basin associated with gravitational foundering of a dense lithosphere. Geophysical and geochemical data support the removal of continental lithosphere beneath the Puna, but the timing and mechanisms by which this removal occurs have remained controversial. We hypothesize that intermontane basin formation in the central Puna is the result of crustal shortening since about 20 Ma, followed by rapid surface uplift, likely related to lithospheric delamination. [ABSTRACT FROM AUTHOR]

Chemical anomalies in polar ice core records are frequently linked to volcanism; however, without the presence of (crypto)tephra particles, links to specific eruptions remain speculative. Correlating tephras yields estimates of eruption timing and potential source volcano, offers refinement of ice core chronologies, and provides insights into volcanic impacts. Here, we report on sparse rhyolitic glass shards detected in the Roosevelt Island Climate Evolution (RICE) ice core (West Antarctica), attributed to the 1.8 ka Taupō eruption (New Zealand)—one of the largest and most energetic Holocene eruptions globally. Six shards of a distinctive geochemical composition, identical within analytical uncertainties to proximal Taupō glass, are accompanied by a single shard indistinguishable from glass of the ~25.5 ka Ōruanui supereruption, also from Taupō volcano. This double fingerprint uniquely identifies the source volcano and helps link the shards to the climactic phase of the Taupō eruption. The englacial Taupō-derived glass shards coincide with a particle spike and conductivity anomaly at 278.84 m core depth, along with trachytic glass from a local Antarctic eruption of Mt. Melbourne. The assessed age of the sampled ice is 230 ± 19 CE (95% confidence), confirming that the published radiocarbon wiggle-match date of 232 ± 10 CE (2 SD) for the Taupō eruption is robust. [ABSTRACT FROM AUTHOR]

With the recent introduction of handheld instruments for field use, laser-induced breakdown spectroscopy (LIBS) is emerging as a practical technology for real-time in situ geochemical analysis in the field. LIBS is a form of optical emission spectroscopy that is simultaneously sensitive to all elements with a single laser shot so that a broadband LIBS spectrum can be considered a diagnostic geochemical fingerprint. Sets of LIBS spectra were collected for seven obsidian centers across north-central California, with data processed using multivariate statistical analysis and pattern recognition techniques. Although all obsidians exhibit similar bulk compositions, different regional obsidian sources were effectively discriminated via partial least squares discriminant analysis. Obsidian artifacts from seven archaeological sites were matched to their putative sources with a high degree of confidence. [ABSTRACT FROM AUTHOR]

The mineralogical and structural properties of the analcime-bearing rocks from Milići (Bosnia and Herzegovina) have been investigated in this work. The analyzed tuff samples, enriched in natural analcime, were characterized through microscopic, DTA/TGA, SEM, and X-ray powder diffraction analysis. The mineralogical composition of the analcime-bearing rocks consists of analcime, quartz, feldspars, mica, carbonates, volcanic glass, zircon, apatite, rutile, and plant fossils. Quantitative XRD analysis shows that the most abundant mineral is analcime. The representative composite sample of analcime-bearing rocks was refined on tetragonal (I41/acd) unit-cell parameters. Tetragonal unit-cell parameters of analcime yielded the best refinement agreement factors (a = 13.7097 (3), c = 13.6953 (4) Å, V = 2571.32 (5) Ǻ3 – Rw = 14.2, Rp = 12.2, Rexp = 8.7, DW stat. = 1.1, GofF = 1.6). The quantitative amounts of main minerals obtained using the Rietveld method yielded before the following results (wt %): analcime 48.79% (RB = 5.99, RF = 5.95), sanidine 29.20% (RB = 2.55, RF = 2.31), biotite 15.99% (RB = 6.56, RF = 3.94), quartz 6.02% (RB = 4.86, RF = 4.63). [ABSTRACT FROM AUTHOR]

Vitrified high level nuclear waste matrices with Fe as network modifier often get associated with lanthanides produced due to fission reactions within irradiated nuclear fuel. During its service period, Fe-lanthanide associations undergo disruptions due to ongoing self-irradiation as well as recovery due to generated heat. Depending on the heat, short-range-order (SRO)/medium-range-order (MRO) of the glass-network, localized crystallization within the amorphous matrix cannot be ruled out. Under this scheme, we investigated atomic-scale structure and chemistry of (Fe, Y) cations (Y as representative of lanthanides) within natural glass, through (Fe, Y) K -edge XAFS measurement of "metamict" gadolinite mineral (FeBe 2 Y 2 Si 2 O 10). The glass is observed to display structural and chemical stability under natural environment over millions of years. We have logistically attributed this superior stability to the advantageous co-existence of (Fe, Y) atoms [vis-à-vis independent Fe and Y atoms]. The importance of (Fe, Y)-site heterogeneity also emerges from our results. Amorphous structure is found to be better stabilized around Fe than Y. Disparate crystallization rates around (Fe, Y) sites can be utilized for separation and recovery of rare earths (e.g. Y) from waste. These conclusions may be generalized to comprehend the control of generic amorphous structure with co-doping of transition metal and rare earth elements. [ABSTRACT FROM AUTHOR]

In-situ Rb–Sr geochronology using LA-ICP-MS/MS technology allows rapid dating of K-rich minerals such as micas (e.g. biotite, muscovite, phlogopite) and K-feldspar. While many studies have demonstrated the ability of the method, analytical protocols vary significantly and to date no studies have provided an in-depth comparison and synthesis in terms of precision and accuracy. Here we compare four calibration protocols based on commonly used reference materials for Rb–Sr dating. We demonstrate that downhole fractionation trends (DHF) for natural biotite, K-feldspar and phlogopite contrast with that for the commonly used Mica-Mg nano-powder reference material. Consequently, Rb–Sr dates calibrated to Mica-Mg can be up to 5 % inaccurate and the degree of inaccuracy appears to be unsystematic between analytical sessions. Calibrating to Mica-Mg also introduces excess uncertainty that can be avoided with a more consistent primary calibration material. We propose a calibration approach involving NIST-610 glass as the primary reference material (RM) and a natural mineral with similar DHF characteristics to the analysed samples as secondary RM to correct for matrix-dependent fractionation. In this work, MDC phlogopite (the source mineral for Mica-Mg nano-powder) was used as the secondary RM, consistently producing accurate Rb–Sr dates for a series of natural biotites and K-feldspars with well-characterized expected ages. However, biotite from the Banalasta Adamellite, Taratap Granodiorite and Entire Creek pegmatite are also suitable secondary RMs for Rb/Sr ratio calibration purposes with consistently <1.5 % fully propagated uncertainties in our methodological approach. Until calibration using isochronous natural standards as the primary RM becomes possible in data-reduction software, the two-step calibration approach described here is recommended. [ABSTRACT FROM AUTHOR]

We quantified the redox state of magma recorded in volcanic glass particles from an ash-forming eruption at Bromo volcano, Indonesia, to obtain insights into its degassing process. An ash sample was collected by real-time sampling from the ash-forming eruption on 24 March 2011. The ash sample contains juvenile glass particles with a brown-colored, transparent appearance. Detailed observations of texture under a field-emission–electron probe micro analyzer show that the brown glasses lack nanoscale crystals in their groundmass. The compositions of groundmass glass (trachy-andesite) and phenocrysts in the brown glass particles indicate a pre-eruptive magma temperature of 1060 ± 20 °C. The Fe3+/ΣFe ratios of the brown glasses were determined to be 0.15–0.24 using synchrotron-based Fe–K edge micro X-ray absorption near-edge structure spectroscopy. From the chemical composition, temperature, and Fe3+/ΣFe data, the oxygen fugacity of the magma is estimated to be in the range of 10−10.3 to 10−8.9, yielding a redox state of ΔQFM = 0.57 ± 0.70. The redox state of magma estimated from the brown glasses is more reduced than that of volcanic gas emitted during the open-vent degassing phase (~ 700 °C and ΔQFM of 1.8). The low temperature and oxidized condition of the volcanic gas can be explained by closed-system cooling from 1060 to 700 °C in the gas phase after outgassing, suggesting that the magma head was located deeper during the open-vent degassing phase than during the ash-forming eruption. The comparison between the redox states of volcanic glass and gas reported in this study gives valuable insights into the degassing process driving volcanic activity. [ABSTRACT FROM AUTHOR]

Characterization of microstructures and perlitic textures may be carried out by combining volcanological and glass technical concepts, with supporting evidence from image analysis. These methods enable investigation of the mechanisms of protracted fracture formation, propagation, and characterization of fracture networks in silica-rich volcanic glass. Here we present analyses of rhyolitic lava and ignimbrites from different locations and geological ages. Our results allow characterization of the relationship between primary sublinear quench fractures and secondary rounded perlitic fractures, which together form a three-dimensional fracture network. Completely hydrated samples from the pre-Cenozoic show no variations in volatile fluid content within fractured glass but do show differential depletion in alkali contents, suggesting significant fluid-mediated alteration. In contrast, younger samples are incompletely hydrated and may demonstrate a connection between alkali mobility and rock hydration. Formation of primary fractures and a first generation of secondary fractures is caused by thermal shock close to the glass transition temperature. Formation and propagation of subsequent fracture generations is related to intrinsic stresses induced by the continued hydration of volcanic glass. We find that the pore space in rhyolitic rocks is not only influenced by fracture porosity or initial vitric porosity but may increase or decrease during post-emplacement, low-temperature alteration processes. [ABSTRACT FROM AUTHOR]

Chaco Canyon in New Mexico was the center of an extensive regional cultural system. The strength of Chaco's regional interactions has been partly defined by the presence of non–local goods including obsidian. We take a diachronic look at Chaco obsidian use from AD 500–1250 using the largest sample of XRF sourced obsidian available to date and combine this with technological analyses to identify significant changes in where and how Chacoans obtained and used obsidian. In the AD 700s obsidian from the more distant Jemez Mountains began to supplant the closer Mt. Taylor obsidian. The obsidian is of roughly equal quality, suggesting this shift relates to social factors and not raw material constraints. We find more variation over time in obsidian source use and acquisition strategies than previously noted. The patterning appears to relate to regional and local cultural diversity, social and organizational heterogeneity, and the development of new exchange networks. [ABSTRACT FROM AUTHOR]

Portable X-ray fluorescence (pXRF) is a useful geochemical technique employed to explore toolstone procurement strategies in the lithic record, commonly utilized in sourcing obsidians. Non-obsidian volcanic toolstones (e.g., dacites, rhyolites, basalts, and andesites) are abundant in interior Alaskan assemblages yet understudied compared to obsidian. Geochemical analyses of these non-obsidian materials offer the potential to gain new insights into ancient toolstone provisioning behaviors. This paper presents a synthesis of geochemical (pXRF) analyses of rhyolite artifacts, systematic regional raw material surveys, and lithic technological analyses collected from nineteen late Pleistocene and Holocene assemblages from the Nenana valley, interior Alaska. Previous research studies on archaeological rhyolites from the region are replicated, new rhyolite artifact groups are identified, and one new rhyolite source is reported and described here. Ultimately, this paper contributes to a growing body of geochemical research seeking to provide a more nuanced look at the complex late Pleistocene and Holocene record of eastern Beringia. [ABSTRACT FROM AUTHOR]

Wavelength‐dependent mid‐infrared (400–1,800 cm−1; 5.56–25 μm) optical constants (real and imaginary indices of refraction; n and k) are determined using reflectance spectra at a spectral sampling of 4 cm−1 for several silicate glasses of varying SiO2 wt% which include (a) basaltic volcanic glass from Kīlauea, Hawaii, (b) synthetic andesite, (c) two synthetic dacites, (d) obsidian volcanic glass from Mount Lassen, California, (e) synthetic rhyodacite, and (f) rhyolitic volcanic glass from Mexico. Because glasses are optically isotropic, no specific orientation was required for spectral measurements, and polished glass samples were measured at random orientations using micro‐FTIR spectrometer. Lorentz‐Lorenz dispersion theory and Fresnel reflectance model for high symmetry materials were used to model the optical constants by optimizing oscillator parameters in modeled spectra to match laboratory spectra. A genetic algorithm (GA) approach automatically finds the natural oscillators and their parameters for each spectrum, and then uses these parameters in a non‐linear least squares optimization routine. The study compared spectral parameters such as Christiansen feature, reststrahlen bands (RBs), and the peaks centered around 860–1,100 (peak 1) and 400–480 cm−1 (peak 2) of n and k to their respective SiO2 wt% of the glasses. CF, RBs, peak 1 of n and k, and peak 2 of n shift to higher wavenumbers with increased SiO2 wt%, whereas peak 2 of k shifts to lower wavenumbers with increased SiO2 wt%. Derived optical constants of these glasses will improve quantitative abundance mapping of volcanic materials on the surfaces of silicate targets in the Solar System. Plain Language Summary: The effective mapping of minerals and their abundances on a planet's surface from orbit is enabled by understanding the nature of the interaction of light of varying wavelengths with the planetary surface. The reflected/emitted light from the surface directly depends on the optical properties of the materials and their interaction with each other. In this study, we numerically modeled the mid‐infrared optical constants of silicate glasses using a genetic algorithm (GA) approach. The GA allows the model to automatically locate the natural harmonic oscillators and their parameters that are responsible for creating the spectral signals that can be detected by spectrometers on orbital spacecraft. Derived optical constants of the glasses could be used in radiative transfer models for quantitative mineral mapping applications. Glasses on planetary surfaces are common in volcanic and/or impact materials and the mid‐infrared spectral range has been widely used to map the surface mineralogy of planets including the Moon and Mars. Mapping the composition and abundance of these glasses therefore will help us to understand the thermal evolution of the planets themselves. Key Points: MIR optical constants (5.56–25 μm; 400–1,800 cm−1) and their oscillator parameters were modeled for seven silicate glasses of varying SiO2 wt%MicroFTIR reflectance spectra of the glasses studied were measured for the spectral region 5.56–25 μm (400–1,800 cm−1)Genetic algorithm was adopted to automatically find the natural oscillators and their parameters for the glasses studied [ABSTRACT FROM AUTHOR]

The study of lunar magma evolution holds significant importance within the scientific community due to its relevance in understanding the Moon's thermal and geological history. However, the intricate task of unraveling the history of early volcanic activity on the Moon is hindered by the high flux of impactors, which have substantially changed the morphology of pristine volcanic constructs. In this study, we focus on a unique volcanic glass found in the lunar meteorite Northwest Africa 11801. This kind of volcanic glass is bead‐like in shape and compositionally similar to the Apollo‐14 and Apollo‐17 very low‐Ti glass. Our research approach involves conducting a comprehensive analysis of the petrology and mineralogy of the volcanic glass, coupled with multiple thermodynamic modeling techniques. Through the investigation, we aim to shed light on the petrological characteristics and evolutionary history of the glass. The results indicate that the primitive magma of the glass was created at 1398–1436°C and 8.3–11.9 kbar (166–238 km) from an olivine+orthopyroxene mantle source region. Then, the magma ascended toward the surface along a non‐adiabatic path with an ascent rate of ~40 m s−1 or 0.2 MPa s−1. During the magma ascent, only olivine crystallized and the onset of magma eruption occurred at ~1320–1343°C. Finally, the glass cooled rapidly on the lunar surface with a cooling rate ranging between 20 and 200 K min−1. Considerable evidence from petrology, mineralogy, cooling rate, and the eruption rate of the glass beads strongly supports the occurrence of ancient explosive volcanism on the Moon. [ABSTRACT FROM AUTHOR]

• TiO 2 -coated self-cleaning glasses are challenging substrates for trace DNA analysis. • TiO 2 -coated glasses, Bioclean® and SaniTise™, most likely degrade trace DNA via photocatalysis. • Rapid trace DNA sample collection reduces impact of photocatalytic DNA degradation. Titanium dioxide (titania, TiO 2) is frequently used as a coating for a variety of self-cleaning products, such as antifogging vehicle mirrors, ceramic tiles, and glass windows because of its distinct physiochemical features. When exposed to light TiO 2 causes photocatalytic decomposition of organic contaminants, potentially compromising DNA integrity. The impact of TiO 2 -coated commercial glasses, Bioclean® and SaniTise™, on trace DNA persistence, recovery, and profiling was investigated. DNA in saliva and touch samples deposited on self-cleaning glass slides exposed to indoor fluorescent light for up to seven days was more degraded than control samples indicating some degree of fluorescent light-induced photocatalytic activity of the self-cleaning surfaces. When exposed to sunlight, DNA yields from saliva and touch samples deposited on the titania-coated substrates decreased rapidly, with a corresponding increase in DNA degradation. After three days no DNA samples applied to self-cleaning glass and exposed to natural sunlight yielded STR profiles. These results suggest that the photocatalytic activation of TiO 2 is the likely mechanism of action underlying the extreme DNA degradation on the Bioclean® and SaniTise™ glasses. Consequently, rapid sample collection and use may be warranted in casework scenarios involving TiO 2 -coated materials. [ABSTRACT FROM AUTHOR]