Mixture Of Rocks Research Articles

The Linear Mixing Approximation in Silica–Water Mixtures at Planetary Conditions

The linear mixing approximation (LMA) is often used in planetary models for calculating the equations of state (EOS) of mixtures. A commonly assumed planetary composition is a mixture of rock and water. Here we assess the accuracy of the LMA for pressure–temperature conditions relevant to the interiors of Uranus and Neptune. We perform molecular dynamics simulations using ab initio simulations and consider pure water, pure silica, and 1:1 and 1:4 silica–water molecular fractions at a temperature of 3000 K and pressures between 30 and 600 GPa. We find that the LMA is valid within a few percent (< ∼5%) between ∼150 and 600 Gpa, where the sign of the difference in inferred density depends on the specific composition of the mixture. We also show that the presence of rocks delays the transition to superionic water by ∼70 GPa for the 1:4 silica–water mixture. Finally, we note that the choice of electronic theory (functionals) affects the EOS and introduces an uncertainty of the order of 10% in density. Our study demonstrates the complexity of phase diagrams in planetary conditions and the need for a better understanding of rock–water mixtures and their effect on the inferred planetary composition.

Producing a siliceous ferroalloy from a mixture of amorphous rocks

The main silicon-containing component in a charge during ferrosilicon smelting is quartzite. The carbothermic reduction rate of the crystalline structure SiO2 has a limitation associated with a fixed energy reserve of silicon-oxygen bond. The reactive capacity of silica can be increased by using its amorphous form instead of the crystalline SiO2. The amorphous form of silica has a higher dispersion, greater free surface energy, and, consequently, a more active degree of entering into a reaction. Such silica-containing materials include amorphous rocks: diatomite, opoka, tripoli. The article presents the results of experimental studies of electrothermal ferrosilicon production from a mixture of amorphous rocks (tripoli, opoka, diatomite with a mass ratio of 1:1:1).It is established that when smelting the mixture of amorphous rocks containing 77 % SiO2, 7.9 % Al2O3, 5.2 % Σ CaO and MgO, 4 % Σ K2O Na2O, 3.3 % Fe2O3, 1.3 % CaCO3, 0.9 % CaSO4, 0.4 % others, three ferrosilicon grades are formed: FeSi25 (22–29 % Si), FeSi45 (41–47 % Si), FeSi50 (47–52 % Si) with the extraction degree of 70–87.6 % silicon into the alloy. Moreover, the ferrosilicon grade decreases with an increase in steel shavings in the charge from 21.9-31.4 % to 33–35 %. In comparison with ferrosilicon smelting from a standard charge containing quartzite with the crystalline form of SiO2, steel shavings and coke, ferrosilicon production from the mixture of amorphous rocks allows to increase the process rate by 17.5–21.6 %. It is possible to increase the silicon extraction degree into the alloy from 80-85 %–94.5 % if its final stage is carried out in the resistance mode. Widespread occurrence in nature, favorable conditions of occurrence, low cost, high reactive capacity are favorable factors for using amorphous rocks in the production of ferroalloys.

Efficient Debris-flow Simulation for Steep Terrain Erosion

Erosion simulation is a common approach used for generating and authoring mountainous terrains. While water is considered the primary erosion factor, its simulation fails to capture steep slopes near the ridges. In these low-drainage areas, erosion is often approximated with slope-reducing erosion, which yields unrealistically uniform slopes. However, geomorphology observed that another process dominates the low-drainage areas: erosion by debris flow, which is a mixture of mud and rocks triggered by strong climatic events. We propose a new method to capture the interactions between debris flow and fluvial erosion thanks to a new mathematical formulation for debris flow erosion derived from geomorphology and a unified GPU algorithm for erosion and deposition. In particular, we observe that sediment and debris deposition tend to intersect river paths, which motivates the design of a new, approximate flow routing algorithm on the GPU to estimate the water path out of these newly formed depressions. We demonstrate that debris flow carves distinct patterns in the form of erosive scars on steep slopes and cones of deposited debris competing with fluvial erosion downstream.

TBM excavation of São Paulo Metro Line 6 South in heterogeneous ground in urban area

AbstractThe São Paulo Metro is expanding its network in the São Paulo Metropolitan Area inhabited by 21 million people. Metro Line 6 connects the north of the city to the existing metro network further South. The construction of Line 6 currently represents the largest infrastructure project in Latin America, combining the excavation of tunnel boring machine (TBM) and conventional tunnels, cut‐and‐cover stations and a number of deep emergency exit shafts. This paper presents the main features of the TBM tunnel excavated in the South stretch through the Tertiary soils of the São Paulo Basin and through the challenging Embu Complex, which consists of a mixture of fractured rock, saprolite and residual soils. The alignment runs under the dense urban grid of São Paulo under high‐rise buildings and other infrastructure, such as existing Metro lines.

Computational model for the thermal conductivity of soil-rock mixture

Soil-rock mixture (S-RM) consists of a mixture of soil and crushed rocks, and their thermal conductivity is highly important in underground engineering. Currently, research on thermal conductivity is primarily focused on soil and rock individually, with minimal attention given to S-RM thermal conductivity. This paper aims to develop a model capable of accurately calculating the thermal conductivity of S-RM by conducting an in-depth analysis of the macrostructure of soil and crushed rocks. First, a series-parallel model of S-RM was developed based on the series-parallel concept of resistors. Second, considering that the intermixing of fine-grained soil and coarse-grained crushed rocks during the fabrication of S-RM results in reduced porosity and elevated saturation - factors that influence thermal conductivity - a refinement has been applied to the generalized thermal conductivity model proposed by Côté and Konrad. The proposed modified model of thermal conductivity is applicable to the S-RM. Finally, the modified model was proven to have high accuracy in predicting the thermal conductivity of S-RM through testing.

LITERATUR REVIEW: PENCEGAHAN CEDERA DAN REHABILITASI PADA PELARI TRAIL

Trail running is sports activity that combines two activities, namely mountain climbing and running. Trail running activities are carried out on mountains that have tracks in the form of paths, in the form of ground stones, or a mixture of sand and small rocks. Trail running was first carried out in the United States of America and continues to develop in Indonesia for example Bandung, Probolinggo, Lombok dan Banyuwangi, Which have been associated in the form of ITRA (International Trail Running Association). The majority of trail running injuries occur in the lower legs, especially the knees and ankles. The main mechanisms underlying injury and injury development include inadequate neuromotor control-balance-coordination ,running through fatigue and abnormal kinematics on a variety of terrain. Pre-Rehabilitation programs such as strengthening the kinetic chain consisting of dynamic flexibility, neuromotor strength and balance, plyometrics exercises can encourage stable and also controlled movement on trails. Educating patients about symptoms of early musculoskeletal soreness and training adjustments also proved to help prevent injuries from developing into serious overuse injuries. Regarding to the increasing number of the injury in trail runners, this article was wrote to describe the role of injury prevention and safe training to reduce the risk of injury and also early rehabilitation program for the injured runners. Study by Vincent et all that review the injury prevention, safe training and rehabilitation to return to sport was the main source in the discussion. The review result showed that educating the runners to prevent injury and how to do the safe running shown a positive impact to reduce the numbers of injury. Early rehabilitation program also shown a good impact in promoting healing in injured runners.

Development of novel resistivity-chargeability statistical relationships for subsurface characterization at Langkawi, Kedah.

The significance of resistivity-chargeability relationships has been acknowledged and applied in various geologic terrains and different environmental conditions. However, there remains an underexplored opportunity to fully utilize these methods in complex geological terrains with a mixture of granitic and sedimentary rocks where empirical relationships have not been established. Such discoveries are crucial for accurately delineating petrophysical and geomechanical properties, which are essential in addressing urgent environmental concerns like landslides, foundation collapse, groundwater shortages, and pollution. To address this research gap, a novel approach was employed: resistivity-chargeability data with simple linear regression modeling. The study focused on developing resistivity-chargeability relationships specifically tailored for tropical granitic environments, using a typical example from Kedah Langkawi, Malaysia. The regions are characterized by complex geological features, ruggedness, and irregular progressive weathering and fracturing of subsurface strata, making the task challenging. Despite these complexities, the study successfully derived an efficient resistivity-chargeability empirical relation that correlates resistivity and chargeability. The derived empirical relationship exhibited high accuracy, surpassing 87%, in predicting chargeability from resistivity datasets or vice versa. This achievement holds great promise in promptly and accurately addressing environmental issues specific to the target region under study. By utilizing this novel resistivity-chargeability relationship, geoscientists, engineers, and environmental practitioners can make informed decisions and effectively manage environmental challenges in these regions, especially during the pre-development stage.

Evaluación de la eliminación de carbamazepina de aguas residuales de hospital en un biofiltro no convencional y aplicación de electro-oxidación como pretratamiento

Hospital wastewater (HWW) is characterized by a high drug concentration, which can cause endocrine effects and bacterial resistance, among others. For this study, carbamazepine (CBZ) was selected as a contaminant model to evaluate the removal efficiency from HWW of recalcitrant pharmaceuticals in a non conventional biofilter (BF), packed with a mixture of wood chips (Prosopis) and porous rock (pouzzolane). The effect of electro-oxidation (EO) as pre-treatment was assessed as well. A biofilm adapted to the HWW was developed in the BF. The addition of high concentrations of CBZ (1 000 and 10 000 µg/l) to the influent HWW did not affect the removal efficiency of the BF to remove organic matter (73 %) and ammonia nitrogen (99 %), proving that the biomass was not inhibited by the CBZ’s concentration. The BF showed a significant removal of CBZ by adsorption during the start up. The bed filter showed an adsorption capacity of 19.84 µg/g (Co = 10 000 µg/l). After the bed filter saturation operated in steady state, the BF removed by biotransformation 17.2 ± 7.4 % of CBZ which, in terms of concentration (1 551 ± 664 µg/l), is bigger than the concentration in most of the reports for hospital, pharmaceutical and municipal WW effluents, which are between 0.1 and 890 µg/l. By applying electro-oxidation as a pretreatment, the global removal efficiency of CBZ increased to 55 ± 5.96 %. In the hybrid system, the EO biotransformed the CBZ, and in the BF the nitrogen and the COD were removed and showed CBZ desorption.

Quantifying denudation rates and sediment recycling of low-relief, high-elevation landscapes using in-situ and meteoric cosmogenic nuclides

Quantifying Earth’s surface denudation rates is crucial for estimating sediment flux and its role in regulating global climate change. The inability of in-situ cosmogenic 10Bein to quantify denudation rates in quartz–free environment has prompted the need for a new proxy–the ratio of meteoric 10Bemet to mineral-weathered 9Be in reactive phase (precipitated in or adsorbed onto secondary minerals). This study utilized 10Bein–26Alin, 10Bemet/9Be, and major element analyses of reactive and mineral phases of bedload sediments to infer basin-wide denudation rates and sediment recycling (reworking of deeply buried sediments) in the Three River Source Region (TRSR) of the central Tibetan Plateau. Results from 10Bein-26Alin analysis of bedload sediments and bedrock samples (quartz grain, 250–500 μm) suggest that the sediments underwent burial events since at least 0.54 ± 0.16 million years ago. Combining paleoclimate records in the central Tibetan Plateau, we interpret the “Great Burial” as most likely the result of climate-controlled deglaciation and denudation at the termination of Naynayxungla glaciation during the MIS 13–15 period. This event marks the first widespread deglaciation on the Tibetan Plateau. The 10Bein-26Alin derived paleo–denudation rates range from 4.2-0.8+0.9 to 151-32+37 mm/kyr, consistent with previous 10Bein–derived modern denudation rates of 10–117 mm/kyr in TRSR. These rates show a moderate positive correlation with regional topography, particularly channel steepness, indicating a decrease in both relief and denudation rates from lower to upper streams. This spatial discrepancy is likely due to enhanced river headward incision and active neotectonic activities in the southeast. Denudation rates derived from the 10Bemet/9Be proxy range from 13 to 248 mm/kyr, alongside a chemical weathering intensity ranging from 43 % to 67 %. These denudation rates are strongly correlated with, but about 1.5 times higher than, the 10Bein–26Alin derived paleo–denudation rates from the same watershed. This suggests that the 10Bemet/9Be extracted from fine grains (<64 μm) may reflect a different sediment recycling pattern compared to 10Bein–26Alin in quartz sediments. Alternatively, the 10Bemet/9Be ratio could indicate a mixture of carbonate rock with a high denudation rate and silicate rock with a lower denudation rate, whereas 10Bein–26Alin reflects a single silicate denudation signal.

Mineral dust and pedogenesis in the alpine critical zone

Abstract. The influence of mineral dust deposition on soil formation in the mountain critical zone was evaluated at six sites in southwestern North America. Passive samplers collected dust for 2 years, and representative soil and rock were gathered in the vicinity of each dust sampler. All materials (dust, soil, and rock) were analyzed to determine their mineralogy (with X-ray diffraction), geochemistry (with inductively coupled plasma mass spectrometry (ICP-MS)), and radiogenic isotope fingerprint (87Sr/86Sr and εNd). In addition, the grain size distribution of dust and soil samples was determined with laser scattering, and standard soil fertility analysis was conducted on the soil samples. Results reveal that minerals present in the dust but absent in the local bedrock are detectable in the soil. Similarly, the geochemistry and isotopic fingerprint of soil samples are more similar to dust than to local bedrock. End-member mixing models evaluating soil as a mixture of dust and rock suggest that the fine fractions of the sampled soils are dominated by dust deposition, with dust contents approaching 100 %. Dust content is somewhat higher in soils compared to bedrock types more resistant to weathering. These results emphasize the dominant control that mineral dust deposition can exert on pedogenesis in the mountain critical zone.

Optimal parameters for producing ferrosilicon from a mixture of diatomite and opoka

In view of the limited reactivity of crystalline silica used in the production of ferrosilicon, it is necessary to search for silica-containing raw materials that have this property to a higher degree. The article presents the results of studies on the production of ferrosilicon from a mixture of amorphous silica-containing rocks – opoka and diatomite in a 1:1 ratio in the presence of coke and steel shavings. The studies have included the electric smelting of the charge in a single-electrode arc furnace and using the second-order rotatable designs of experiments (Box-Hunter plans) followed by graphical optimization. The research has established that FeSi25 (24.5-30% of Si), FeSi45 (41-47% of Si), and FeSi50 (47-51% of Si) grades of ferrosilicon can be smelted from a mixture of diatomite and opoka, depending on the amount of coke and steel shavings. The optimal parameters for producing FeSi25 ferrosilicon (with the extraction of 80-82.4% of silicon into the alloy) were 35.0-37.2% of coke and 33.75-35.0% of steel shavings. FeSi45 ferrosilicon (with extraction of 80-84.6% of silicon) was formed with 38.0-45.0% of coke and 29.2-33.2% of steel shavings. At 40.4-45.0% of coke and 29.2-31.1% of steel shavings, FeSi50 ferrosilicon was formed; the extraction of silicon into the resulting alloy was more than 80-81.5%. At the balance electric smelting of the diatomite and opoka mixture in the presence of 45% of coke and 30% of steel shavings, ferrosilicon of FeSi50 grade (51.8-52.6% of Si) was produced with the 82% silicon extraction degree.

Study on the microstructure and soil quality variation of composite soil with soft rock and sand

Abstract Aiming at the remediation of Mu Us Sandy Land, which is one of the four major sandy areas in China, the local soft rock was selected as the remediation material for sand improvement, and the soil quality changes after the compounding of soft rock and sand were analyzed. The results show that the clay minerals in the soft rock are closely cemented to each other, forming a rich pore structure with a high hydrophilic, large specific surface and interlayer space. With the treatment of 1:1 and 1:2 soft rock/sand, there are more attachments on the surface of soil particles, and most of the particles are in contact with each other. The content of polysaccharides in the compound soil after the mixture of soft rock and sand is significantly higher than that of total sand treatment. With 1:1 of soft rock/sand, the content of free ferric oxide increased gradually with the depth of the soil layer. The organic carbon content in the 0–10 and 20–30 cm soil layers showed a good change. After the addition of arsenic sandstone, the soil cementation of compound soil and the content of polysaccharides and organic carbon have been significantly changed. Soft rock is a kind of natural material conducive to the improvement of sandy soil.

Reaction synthesis of porous nano-structured mullite ceramic composites from alumina and zeolite-poor rock with enhanced strength and low thermal conductivity

Porous mullite-based ceramics have been developed using a mixture of zeolite-poor rock and alumina through mechanical activation and reactive sintering. The experimental findings demonstrate that the in-situ mullite growth may develop in a variety of shapes, including whiskers, nanofiber, nanonetwork and diamond-like particles. The XRD examination indicates that the samples sintered at 1500 °C are mostly made of the mullite phase. The SEM photographs show that as the sintering temperature increases, the mullitization process takes place first in zeolite-poor rock particles, and subsequently, alumina combines with the silica-containing phase via a liquid-phase sintering mechanism to produce an interlocking network of extended secondary mullite. The effects of mullite formation and the sintering temperature on various properties of the sintered samples, such as their density, apparent porosity, thermal conductivity, strength, wear resistance, composition, morphologies, and microstructural characteristics of the sintered samples were studied. Increasing the sintering temperature from 1100 to 1500 °C improved the different properties. The density increased from 1.9 to 2.1 g/cm3, thermal conductivity rose from 0.9 to 1.6 W/m.K, compressive strength escalated from 18.9 to 92.1 MPa, and worn material volume decreased from 2444 to 36.9 mm3 after a 5-min abrasion test.

Evaluation of native herbaceous plants for green roof applications in Istanbul

Green roofs are important components by providing several benefits in urban environments. To achieve these benefits, appropriate plant selection is crucial. Therefore, a study was conducted to evaluate the plant diversity of the Istanbul and Marmara Region of Turkey for potential native suitable plants for green roofs. In this regard, suitable plants for extensive green roofs were investigated among international studies. Detected plant species were compared to taxa in the A2 grid square of Flora of Turkey P.H. Davis (1965-1985). At the second stage of the study, among listed plants, specific open field measurements were performed on 5 selected native plant species including Anthemis tinctoria L., Euphorbia myrsinites L., Prunella vulgaris L., Stachys thirkei C.Koch and Veronica chamaedrys L., which were collected from their natural habitats in Marmara region. The selected plants were placed in two different substrates, each comprising a mixture of lava rock or pumice with municipal waste compost in a volume ratio of 8:2. Measurements, including plant growth index, chlorophyll fluorescence, plant coverage ratio, and plant taxa survival, were conducted over a study period of 53 weeks. All the plant species have reached the phenomenological stage of blossoming in the study. The highest survival rate was observed on Veronica chamaedrys grown in pumice substrates treatments. Prunella vulgaris well adapted to the green roof environment. Despite the number of individual losses, Stachys thirkei exhibited a relatively higher revitalization ability, while Euphorbia myrsinites demonstrated greater drought resistance. A.tinctoria failed to adapt to the limited green roof substrate depth.

Anorthositic lunar regolith breccia Dhofar 1769—Clear indications for repeated mixing of impact melt lithologies

AbstractThe lunar regolith breccia Dhofar 1769, which was found in 2012 as a single 125 g piece in the Zufar desert area of Oman, contains a relatively large, dark‐colored impact melt breccia embedded in a fine‐grained clastic matrix. The internal texture of the fragment indicates the repeated melt breccia formation on the lunar surface, their repeated brecciation, and mixing in second, third, and fourth generations of brecciated rock types. The chemical and mineralogical data reveal the incorporation of a feldspar‐rich subophitic crystalline melt within a feldspar‐rich microporphyritic crystalline melt breccia. This lithic paragenesis itself is embedded within a mafic, crystalline melt breccia. The entire breccia with the three different impact melts has been finally incorporated into the whole rock breccia. The three impact melts are mixtures of different source rocks and impact projectiles, based on the obtained minor and trace element compositions (in particular of Ni and the rare earth elements [REE]) of the impact melt lithologies. For all processes of impact melt formation, additional steps of their brecciation and re‐lithification require a minimum number of seven impact processes.

Влияние статической нагрузки от горнотранспортного оборудования на устойчивость уступов, расположенных в скальных породах

Most of the enterprises applying open-pit mining method at deposits face challenges of pit wall steepening when approaching the pit wall to the final position or reducing productivity. The main task when increasing the angle of pit slope is to determine its stability. One of the ways to steepen the open-pit wall is to increase the slope angle of benches composing the open-pit wall. The bench stability is primarily determined by its physical properties and structural uncertainty. The higher the strength properties of rocks, the steeper the slope angle formed in these rocks can be. The "Rules of stability..." provide for the possible accounting the loads from mining equipment when assessing the stability, but this possibility is provided for the calculation of bench stability of open-pits and cuts, formed by semi-hard and dispersed rocks, dumps formed from clay or semi-hard rocks and (or) from a mixture of clay and hard rocks. At the same time, it is of interest to assess the impact of static loading from the located mining transport equipment in a stationary state on the stability of the benches located in hard rocks. It is shown that the load from the track dozer scraping the berms has an impact of no more than 6-7% for a distance of about 15 m from the top crest of a 30-meter long bench with a slope angle of 80° to the edge of the track, which is generally insignificant for maintaining bench stability. The minimum value of the safety factor of the bench with the load from the BELAZ-75306 mining dump truck is at a distance of 8 to 10 m from the top crest to the edge of the wheel. That is, at this distance the mining dump truck has the maximum impact. At 30 m distance from the bench’s top crest, mining dump truck has no impact on the bench stability. The maximum impact of the dump truck on the stability is 22 to 25%.

Thermodynamic Justification of Obtaining Ferroalloy from a Mixture of Chrysotile-Asbestos Waste and Carbonaceous Rock

The results of research on the thermodynamic prediction of obtaining ferroalloys with the reduction and distillation of magnesium from a mixture of chrysotile-asbestos waste produced by Kostanay Minerals JSC and carbonaceous rock are presented. The research was carried out by thermodynamic modelling methods using the HSC-6.0 Chemistry software package of the Finnish metallurgical company Outokumpu based on the principle of the Gibbs minimum energy and a rotatable second-order plan (the Box-Hunter plan). Based on the conducted studies on the distribution of Si, Al, Mg between the condensed and gas phases, it was found that the formation of ferrosilicoaluminum of the FS45A10 brand with a content of 7.5-10.1% Al and 42.5-44% Si occurs in the presence of 25-25.9% iron at 1959-2000°C; ferrosilicon of the FS45 brand with a content of 41.0-44.4% Si and &lt; 2.5% Al is formed in the temperature range of 1800-1877°C in the presence of 25.4-35% iron. In addition to branded ferrosilicon and ferrosilicoaluminum, it is possible to obtain Fe-Si-Al ligatures containing 2.5-10.1% Al and 41.0-44.7% Si from a mixture of chrysotile-asbestos production wastes and carbonaceous rock. In the presence of 25

Submarine landslide susceptibility assessment along the southern convergent margin of the Colombian Caribbean

Submarine landslides are a mixture of rock, sediment, and fluids moving downslope due to a slope's initial event of mechanical failure. Submarine landslides play a critical role in shaping the morphology of the seafloor and the transport of sediments from the continental shelf to the continental rise in the southern margin of the Colombian Caribbean. Two fundamental considerations can be highlighted: first, mass transport complexes produced by submarine landslides encompass significant portions of the stratigraphic record; second, these mass movements could affect underwater infrastructure. The mapping of the Southern Caribbean seafloor using 3D seismic surveys and multibeam bathymetry data in an area encompassing 59,471 km2 allowed the identification of 220 submarine landslides with areas ranging between 0.1 and 209 km2. Distinctive characteristics were found for submarine landslides associated with canyon walls, channel-levee systems, tectonically controlled ridges, and the continental shelf break. The analysis of the relationship between submarine landslides and seafloor morphological features made it possible to estimate a mass movement susceptibility map that suggests the following considerations: first, structural ridges and adjacent intraslope subbasins related to the South Caribbean Deformed Belt are more likely to be submarine landslide hazards; second, the continental shelf break and channelized systems produce a moderate submarine landslide hazard potential; and third, deep marine systems with a slope less than 5° show the lowest submarine landslide hazard potential. This work contributes to the understanding of submarine landslides in the study area through the presentation of conceptual diagrams that provide additional visual elements facilitating the level of abstraction necessary for visualizing bathymetric data. Likewise, the mass movement susceptibility map presented herein gives insights for future studies that seek to evaluate geohazards in the southern Colombian Caribbean margin.

Carbon-rich icy moons and dwarf planets

Density and moment of inertia of icy moons and dwarf planets suggest the presence of a low-density carbonaceous component in their rocky cores. This hypothesis was tested using inner density structure and thermal models. Rocky core densities in dwarf planets and icy moons are found to consist of a mixture of chondritic silicate-sulfide rocks and carbonaceous matter. Carbonaceous matter was originally mixed with ice in a rock-free precursor. In a homogeneous accretion scenario where these components are mixed in solar proportions, ices then differentiated from the carbon-rich refractory core, while hydration of silicates could take place. Thermal models taking into account the presence of carbonaceous matter suggest that originally hydrated silicates are only partially dehydrated in the refractory cores of most moons. Viable scenarios point to a difference in formation or evolution between Ganymede and Titan in spite of their similar size and mass. Fully dehydrated mineralogies, inferred in Europa and possibly the densest dwarf planet Eris, require heterogeneous accretion near the water snow line of the solar or circumplanetary nebula. Progressive gas release from slowly warming carbonaceous matter-rich cores may sustain up to present-day the replenishment of ice-oceanic layers in organics and volatiles. It accounts for the observation of nitrogen, light hydrocarbons and complex organic molecules at the surface, in the atmospheres, or in plumes emanating from moons and dwarf planets. The formation of large carbon-rich bodies in the outer solar system suggests that carbon-rich planets could form at the outskirts of extrasolar systems.

Multi-component avalanches for rock- and ice-falls to potential debris flow transition modelling

Rock/ice avalanches are complex gravitational flows involving three important physicalprocesses: entrainment, phase-changes, and flow transitions. The basic complexity of modelling rock/ice avalanches lies in the fact that the flow is a mixture of rock, ice, water, snow, soil sediments. The interaction of these components can lead to flow transitions which is difficult to model with simplified flow rheologies. For example, a flow initially composed of rocks and ice can transition into a long-runout debris flow, dependent on the entrainment of water, water-saturated sediments and/or snow. The dynamic behaviour of rock/ice avalanches is therefore highly difficult to predict because the flow mixture is dependent on the hydrological and geomorphological properties along the avalanche track. These properties can vary from year to year but even from season to season. The problem is intensified by the fact that frictional shearing can produce enough heat energy to melt ice and snow, leading to additional water in the flow. In this contribution, we present a new RAMMS module specifically designed to simulate single- and multicomponent avalanches of rock, ice, water, snow, and ice. The rheology of the flow is treated by using the concept of component activation energy. The model includes both snow and sediment/water/ice entrainment modules. A unique feature of the model is that it tracks the temperature of the rock, ice and water phases and therefore can treat phase changes. We apply the model on the Chamoli case-study to highlight the potential and present limitations of the model..