Hasil untuk "Mineralogy"

T. Matschei, B. Lothenbach, F. Glasser

C. Feller, M. Beare

Gengying Li, Pei-ming Wang, Xiaohua Zhao

E. Slessarev, Yang Lin, N. Bingham et al.

Ahmed Khalifa, Ö. Cizer, Y. Pontikes et al.

Abstract To future-proof alkali-activation technology, there is a need to look beyond well-established precursors such as fly ash and blast furnace slag, due to resource competition, geographical distribution and technical limitations. Clay minerals are abundant and diverse aluminosilicate resources available around the world. However, due to the mineralogical complexity amongst the most common 1:1 (kaolinite, halloysite) and 2:1 (montmorillonite, illite) clay minerals, and practical issues such as workability, their use has been more limited. Recent advances have improved understanding both of pre-activation treatments (thermal, mechanical, chemical), and of the factors influencing clay reactivity, phase assemblages and properties of final products. This opens new opportunities for the exploitation of these resources to produce sustainable cements. A one-size-fits-all approach for processing and activating clay minerals is not viable. Instead, activation routes need to be tailored according to the clay mineralogy to achieve the binder properties required for key applications.

J. Mustard, S. Murchie, S. Pelkey et al.

F. Rajabipour, Eric R. Giannini, C. Dunant et al.

A. Borst, Martin P. Smith, A. Finch et al.

Global resources of heavy Rare Earth Elements (REE) are dominantly sourced from Chinese regolith-hosted ion-adsorption deposits in which the REE are inferred to be weakly adsorbed onto clay minerals. Similar deposits elsewhere might provide alternative supply for these high-tech metals, but the adsorption mechanisms remain unclear and the adsorbed state of REE to clays has never been demonstrated in situ. This study compares the mineralogy and speciation of REE in economic weathering profiles from China to prospective regoliths developed on peralkaline rocks from Madagascar. We use synchrotron X-ray absorption spectroscopy to study the distribution and local bonding environment of Y and Nd, as proxies for heavy and light REE, in the deposits. Our results show that REE are truly adsorbed as easily leachable 8- to 9-coordinated outer-sphere hydrated complexes, dominantly onto kaolinite. Hence, at the atomic level, the Malagasy clays are genuine mineralogical analogues to those currently exploited in China. Global resources of heavy Rare Earth Elements (REE) are dominantly sourced from Chinese regolith-hosted ion-adsorption deposits, yet the adsorption mechanisms remain unclear. Here, the authors find that heavy REE are adsorbed as easily leachable 8-coordinated outer-sphere hydrated complexes, dominantly onto kaolinite, in clays from both China and Madagascar.

L. Tauxe, R. Butler, R. Voo et al.

1. THE PHYSICS OF MAGNETISM 2. THE GEOMAGNETIC FIELD 3. INDUCED AND REMANENT MAGNETISM 4. MAGNETIC ANISOTROPY AND DOMAINS 5. MAGNETIC HYSTERESIS 6. MAGNETIC MINERALOGY 7. HOW ROCKS GET AND STAY MAGNETIZED 8. APPLIED ROCK (ENVIRONMENTAL) MAGNETISM 9. GETTING A PALEOMAGNETIC DIRECTION 10. PALEOINTENSITY 11. FISHER STATISTICS 12. BEYOND FISHER STATISTICS 13. PALEOMAGNETIC TENSORS 14. THE ANCIENT GEOMAGNETIC FIELD 15. THE GPTS AND MAGNETOSTRATIGRAPHY 16. TECTONIC APPLICATIONS OF PALEOMAGNETISM

A. Keneti, B. Sainsbury

Abstract Through a review of selected published case study data from around the world, in situ conditions that contribute to rockburst events have been identified. This review was carried out to assist research associated with developing numerical modelling techniques to reproduce rockbursting within a large-scale (mine models) for predictive purposes. Contributing factors identified through the case study review include unfavourable stress states, excavation geometry (size and orientation in relation to the principal stresses) and rate and direction of advance. Factors also incorporated unfavourable rock mass characteristics that included mineralogy, contrasts in geomechanical properties, and geological intensifiers (dykes, faults, etc.).

Tomoki Nakamura, T. Noguchi, Masahiko Tanaka et al.

Paul L. Younger

Martin J. S., Kobus J., Varga J. et al.

Context. The physical conditions and processes taking place in the innermost regions of protoplanetary disks are essential for planet formation and general disk evolution. In this context, we study the T-Tauri type young stellar object RY Tau, which exhibits a dust-depleted inner cavity characteristic of a transition disk. Aims. The goal of this study is to analyze spectrally resolved interferometric observations in the L, M, and N bands of the RY Tau protoplanetary disk obtained with MATISSE. We aim to provide constraints on the spatial distribution and mineralogy of dust in the inner few astronomical units by producing synthetic observations fitting the interferometric observables. Methods. We employed a 2D temperature gradient disk model to estimate the orientation of the inner disk. Successively, we analyzed the chemical composition of silicates depending on spatial region in the disk. Finally, we sampled the parameter space of a viscous accretion disk model via Monte Carlo radiative transfer simulations to investigate the actual 3D dust density distribution of RY Tau. Results. We constrained the orientation of the inner disk of RY Tau, finding no evidence of significant misalignment with respect to its outer disk. We identified several silicate species commonly found in protoplanetary disks and observed a depletion of amorphous dust grains toward the central protostar. By simultaneously considering the observed visibilities and the spectral energy distribution (SED), we found that an accretion disk and an optically thin envelope enshrouding the protostar fits the observations best. Radiative transfer simulations show that hot dust close to the protostar and in the line of sight (LOS) to the observer, either in the uppermost disk layers of a strongly flared disk or in a dusty envelope, is necessary to model the observations. The shadow cast by a dense innermost disk midplane on the dust further out explains the observed closure phases in the L band and (to some extent) in the M band. However, the closure phases in the N band are underestimated by our model, hinting at an additional asymmetry in the flux density distribution that is not visible at shorter wavelengths.

J. Mohren, J. Mohren, H. Wiesel et al.

<p>Loss of soil organic matter (SOM) from arable land poses a serious threat to soil fertility and crop yields, and it thwarts efforts to conserve soils as carbon sinks to mitigate global warming. Wind erosion can be a major factor in the redistribution of soil fines including SOM, but assessments of its impact have typically been limited by short observation periods of a few years at most. Longer time frames, extending back to the mid-20th century, may however be probed using the concentrations of radionuclides that were globally distributed by nuclear weapon tests conducted during the 1950s and early 1960s. The basic concept is that differences in fallout radionuclide (FRN) activities between undisturbed and arable soils can be used to infer soil particle redistribution. In the present work, we have measured activities of <span class="inline-formula">¹³⁷Cs</span> and <span class="inline-formula">^239+240Pu</span> in soils from three agricultural regions of the plains of the South African Highveld. The three regions represent distinct agroecosystems, and within each region the temporal length of cultivation varies from 0 (i.e. native grassland) to almost 100 years. Wind erosion has previously been shown to play a dominant role in soil particle loss from agricultural sites in the Highveld, and the level plots we investigate here did not show any evidence of fluvial erosion. Hence, we interpret the fate of soil fines, including SOM, to be governed by wind erosion. For the cultivated soils, radionuclide activities are found to be less than in adjacent native grassland, and the magnitude of the reduction is strongly correlated with the duration of cultivation. Specifically, the original inventories of both <span class="inline-formula">¹³⁷Cs</span> and <span class="inline-formula">^239+240Pu</span> are approximately halved after <span class="inline-formula">∼20</span>–40 <span class="inline-formula">years</span> of cropping. The initial rate loss relative to the undisturbed soils is, however, considerably higher, with <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M7" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>∼</mo><mn mathvariant="normal">6</mn><mspace width="0.125em" linebreak="nobreak"/><mrow class="unit"><mi mathvariant="normal">%</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">yr</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="50pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="18a9b47a1387db42b5129f30f943d719"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-22-1077-2025-ie00001.svg" width="50pt" height="15pt" src="bg-22-1077-2025-ie00001.png"/></svg:svg></span></span> recorded during the first year after native grassland is converted to arable land. We correlate our radionuclide data with previously published SOM contents from the same sampled material and find that the radionuclides are an excellent indicator of SOM decline at the sites we investigate. We conclude that wind erosion can exert a dominant control on SOM loss in arable land of South Africa.</p>

Anant Aishwarya Dubey, Pelina Toprak, Allan Pring et al.

Abstract Bacterial mineralisation of calcium carbonates (CaCO3) has become a focal point of interest in the scientific community owing to their versatile applications as biomaterials. However, despite extensive research, the knowledge on factors influencing biogenic CaCO3 polymorph (calcite, vaterite or aragonite) selection in nature remains obscure. Bacterial mineralisation happens in nature on diverse substrates by different pathways, often in the presence of organic matter such as biofilm and extracellular polymeric substances (EPS) secreted with the regular metabolic activities of microbes. This study examines the bacterial CaCO3 mineralisation process by two distinct pathways on different natural substrates with advanced analytical techniques, including Time of Flight- Secondary Ions Mass Spectrometry (ToF-SIMS). A high EPS-producing microbe (Bacillus subtilis, BS) was compared with the standard ureolytic strain (Sporosarcina pasteurii, SP). Natural geological minerals, including apatite, calcite and quartz, were selected as substrates. This study demonstrates that SP favours the precipitation of rhombohedral calcite crystals (2 to 40 μm in size), regardless of the mineral substrate. In contrast, the EPS-producing BS culture induced the formation of significantly larger vaterite structures (20 to 100 μm in size) in spheroid and hexagonal shapes. The mineralogy of precipitates was confirmed with Raman spectroscopy. ToF-SIMS enabled the spatial tracking of organic macromolecules and the adsorption of calcium ions on them. The functional groups of the EPS involved in these interactions were characterised by Fourier Transform Infrared Spectroscopy (FTIR). This study reveals that microbial activity dominates over substrate mineralogy in selecting the phase and shaping the morphology of biogenic CaCO3, with EPS playing a crucial role in promoting the aggregation of small nanocrystals into large vaterite structures and their stabilisation.

Peng-Fei Zhang, Mei-Fu Zhou, Paul T. Robinson et al.

Abstract Ophiolites, mostly formed via subduction initiation at proto-forearcs, exhibit a unique variation of mantle-derived magmatism from MORB-like to low-Ti tholeiitic and boninitic-like affinities. Such variation was suggested to form chromite deposits spanning high-Al to high-Cr types. Nevertheless, the origin of diverse magmatism during subduction initiation and their linkages to different chromite deposits has long been enigmatic. Here we show elemental and Os isotopic compositions of different chromitites from the Zambales ophiolite, Philippines. Combined with data from ophiolites worldwide, high-Al and high-Cr chromitites are revealed to result from low-Ti tholeiitic and boninitic-like magmatism, respectively. Proto-forearc mantle had few chromitites generated during MORB-like magmatism, but afterwards, it was modified first by slab fluids and later by continuous asthenospheric upwelling in the context of slab densification and rollback. The latter modification elevated the geothermal gradient and replenished fertile components in the proto-forearc mantle progressively, inducing increasingly higher degrees of mantle melting and Cr-richer magmatism and chromitites.

حمید گرانیان

برگه 1:100.000 پرنگ در استان خراسان جنوبی به دلیل دارا بودن سنگ‌های ولکانیکی و پلوتونیکی حد واسط تا فوق ‌بازیک و تنوع سنگ‌های رسوبی، مستعد کانی‌سازی‌های اسکارنی، ماسیوسولفیدی و رسوبی است. در این مقاله ضمن معرفی روش تحلیل مختصات اصلی (PCoA)، از این روش به همراه روش تحلیل مولفه‌های اصلی (PCA) و تحلیل تطبیقی (CA) برای شناسایی نوع کانی‌سازی محتمل در این برگه استفاده شده است. برای این منظور داده‌های زمین‌شناسی و معدنی به همراه نتایج تجزیه 25 عنصر بر روی 314 نمونه‌ رسوبات آبراهه‌ای از منطقه مورد مطالعه به کار رفته است. نتایج تحلیل داده‌ها نشان می‌دهد که نقشه‌های مختصات نمونه‌ها در بعد D1، امتیاز نمونه‌ها در مولفه‌ PC1 و موقعیت نمونه‌ها در خوشه اول با کانی‌سازی در سنگ‌های اولترابازیک، بازیک و لیستونیت‌ها به عنوان محتمل‌ترین پتانسیل ارتباط دارند. پس از آن نقشه‌های بعد D2 و D3، مولفه‌ PC2 و PC5 و نمونه‌های خوشه پنجم مرتبط با سنگ‌های رسوبی بیشترین احتمال را به کانی‌سازی‌های رسوبی به ویژه از نوع Mn و Fe در منطقه نسبت می‌دهند. کمترین احتمال کانی‌سازی مرتبط با کانی‌سازی‌های اسکارنی و ماسیوسولفیدی است که نقشه‌های بعد D4، مولفه‌ی PC3 و نقشه موقعیت نمونه‌های خوشه‌های دوم، سوم و چهارم محدوده آنها را پیش‌بینی می‌کند. همچنین مقایسه نتایج تحلیل داده‌ها با روش‌های آمار چندمتغیره نشان می‌دهد که در کاهش یافتن بعد داده‌های اولیه، روش مولفه‌های اصلی نسبت به روش بعدهای اصلی تغییرپذیری بیشتری را پوشش می‌دهد. در حالی که ارتباط دادن نقشه‌های مختصات نمونه‌ها در بعدهای اصلی نسبت به نقشه‌های امتیاز نمونه‌ها در مولفه‌های اصلی و نمونه‌های هر خوشه با کانی‌سازی راحت‌تر و با اعتبار بالاتری صورت می‌گیرد، بنابراین پیشنهاد این مقاله استفاده همزمان از دو روش PCoA و PCA در کنار سایر روش‌های آمار چندمتغیره برای تحلیل داده‌های ژئوشیمیایی در یک منطقه است.

Soultana Kyriaki Kovaiou, Anastasia Kokkari, George Floros et al.

In recent years, the number of available chemical pesticides has been dramatically reduced, urging the need for the discovery of alternatives to chemical pesticide products such as, among others, natural zeolites (zeolitic rocks). We determined the mineralogical and chemical composition of a specific and continuous layer of zeolitic rock sample (ZeotP) from Petrota, Evros, Greece, and evaluated its oviposition-deterrent effect on the olive fruit fly <i>Bactrocera oleae</i> Gmelin (Diptera: Terphritidae). The tested natural zeolite contained 70 wt. % clinoptilolite, 18 wt. % amorphous material, 7 wt. % feldspars, 4 wt. % cristobalite, and 1 wt. % quartz. We tested the oviposition-deterrent effect of ZeotP mixed or not with an emulsifier adjuvant, NU-FILM-P^®, in water and applied it to the surface of olive fruits. The ZeotP oviposition-deterrent effect on the olive fly was very high under a series of tested temperatures (17 °C, 20 °C, 25 °C, and 30 °C) and RHs (23%, 33%, 55%, 75%, and 94%). In addition, the ZeotP residual deterrent effect after equable water spraying was high, like the respective effect of the pyrethroid insecticide Decis^® (deltamethrin). Our results may contribute to the effective control of the olive fruit fly using an alternative to chemical pesticides: natural zeolite (zeolitic rocks) products.

W. M. van der Meij, A. J. A. M. Temme, S. A. Binnie et al.

<p>Understanding long-term soil and landscape evolution can help us understand the threats to current-day soils, landscapes and their functions. The temporal evolution of soils and landscapes can be studied using geochronometers, such as optically stimulated luminescence (OSL) particle ages or radionuclide inventories. Also, soil–landscape evolution models (SLEMs) can be used to study the spatial and temporal evolution of soils and landscapes through numerical modelling of the processes responsible for the evolution. SLEMs and geochronometers have been combined in the past, but often these couplings focus on a single geochronometer, are designed for specific idealized landscape positions, or do not consider multiple transport processes or post-depositional mixing processes that can disturb the geochronometers in sedimentary archives.</p> <p>We present ChronoLorica, a coupling of the soil–landscape evolution model Lorica with a geochronological module. The module traces spatiotemporal patterns of particle ages, analogous to OSL ages, and radionuclide inventories during the simulations of soil and landscape evolution. The geochronological module opens rich possibilities for data-based calibration of simulated model processes, which include natural processes, such as bioturbation and soil creep, as well as anthropogenic processes, such as tillage. Moreover, ChronoLorica can be applied to transient landscapes that are subject to complex, non-linear boundary conditions, such as land use intensification, and processes of post-depositional disturbance which often result in complex geo-archives.</p> <p>In this contribution, we illustrate the model functionality and applicability by simulating soil and landscape evolution along a two-dimensional hillslope. We show how the model simulates the development of the following three geochronometers: OSL particle ages, meteoric <span class="inline-formula">¹⁰</span>Be inventories and in situ <span class="inline-formula">¹⁰</span>Be inventories. The results are compared with field observations from comparable landscapes. We also discuss the limitations of the model and highlight its potential applications in pedogenical, geomorphological or geological studies.</p>

Michael I. Ojovan, Sergey V. Yudintsev

We briefly overview the utilisation of glasses, ceramics and glass crystalline materials (GCMs) composed of both vitreous and crystalline phases focusing on nuclear waste immobilisation and potential use of some advanced waste forms for incorporation of the rare earth elements (REE) and minor actinide (MA: Am, Cm) fraction of high-level waste (HLW).