Comparison of Measured and PTF Predictions of SWCCs for Loess Soils in China

There are significant advantages in using indirect pedo-transfer functions, (PTFs) for the estimation of unsaturated soil properties. The pedo-transfer functions can be used for the estimation of the soil–water characteristic curve (SWCC) which in turn is used for the estimation of other unsaturated soil properties. The accuracy of the indirect pedo-transfer function method for the estimation of the SWCC depends on the PTF and the equation used to best-fit the particle-size distribution (PSD) data. The objectives of this study are to: (1) evaluate the performance of the Fredlund et al. (Can Geotech J 37:817–827, 2000) equation for best-fitting the particle-size distribution, (PSD) data, and, (2) compare the predictions made by two of the commonly used PTFs; namely, Arya and Paris (Soil Sci Soc Am J 45:1023–1030, 1981) and Fredlund et al. (Can Geotech J 39:1103–1117, 2002), for estimating the SWCC from the PSD. The authors used 258 measured PSDs and SWCC datasets from the Loess Plateau, China, for this study. The dataset consisted of 187 silt–loam soils, 41 loam soils, 11 silt–clay–loam soils, 10 sand–loam soils, 6 silt–clay soils, and 3 loam–sand soils. The SWCC and PSD datasets were measured using a Pressure Plate apparatus and the pipette method, respectively. The comparison between the estimated and measured particle-size distribution curves showed that the Fredlund et al. (Can Geotech J 37:817–827, 2000) equation closely prepresented the PSD for all soils in the Loess Plateau, with a lower root mean square error (RMSE) of 0.869%. The comparison between the estimated and measured water contents at the same suction showed that the Fredlund et al. (Can Geotech J 39:1103–1117, 2002) PTF performed somewhat better than the Arya and Paris (Soil Sci Soc Am J 45:1023–1030, 1981) function. The Fredlund et al. method had RMSE value of 0.039 cm³ cm⁻³ as opposed to 0.046 cm³ cm⁻³ for the Arya and Paris (Soil Sci Soc Am J 45:1023–1030, 1981) method. The Fredlund et al. (Can Geotech J 39:1103–1117, 2002) PTF produced the closest predictions for sand–loam, loam–sand, and loam soils, with a lower RMSE for gravimetric water content ranging from 0.006 to 0.036 cm³ cm⁻³. There were consistent over-estimations observed for silt–loam, silt–clay–loam, and slit–clay soils with RMSE values for gravimetric water content ranging from 0.037 to 0.043 cm³ cm⁻³. The measured and estimated air-entry values were closest when using the Fredlund et al. (Can Geotech J 39:1103–1117, 2002) PTF. The measured and estimated maximum slopes on the SWCC were closest when using the Arya and Paris (Soil Sci Soc Am J 45:1023–1030, 1981) PTF.     

Residual and Fully Softened Strength Evaluation of Soils using Artificial Neural Networks

A backpropagation artificial neural network (ANN) model is developed to predict the secant friction angle of residual and fully softened soils, using data reported by Stark et al. (J Geotech Geoenviron Eng ASCE 131:575–588, 2005). In the ANN model, index properties such as liquid limit, plastic limit, activity, clay fraction and effective normal stress are used as input variables while secant residual friction angle is used as output variable. The model is verified using data that were not used for model training and testing. The results also indicate that the secant residual friction angle of cohesive soils can be predicted quite accurately using liquid limit, clay fraction and effective normal stress as input variables with R ² = 0.93. The sensitivity analysis results indicate that plastic limit and activity have no appreciable effect on ANN predicted secant friction angles. The secant friction angle predictions of the ANN model were also compared with those of Stark’s et al. (2005) curves and the empirical formulas suggested for the same data sets by Wright (Evaluation of soil shear strengths for slope and retaining wall stability with emphasis on high plasticity clays, 2005). The comparison shows that the ANN model predictions are very close to those suggested by the Stark et al. (2005) curves but much better than the prediction of Wright’s (2005) empirical equations. The results also show that ANN is an alternative powerful tool to predict the secant friction angle of soils.     

Oxygen isotope heterogeneity of the mantle beneath the Canary Islands: a discussion of the paper of Gurenko et al.

Gurenko et al. (Contrib Mineral Petrol 162:349–363, 2011) report laser-assisted fluorination (LF) and secondary ionization mass spectrometry (SIMS) ¹⁸O/¹⁶O datasets for olivine grains from the Canary Islands of Gran Canaria, Tenerife, La Gomera, La Palma and El Hierro. As with prior studies of oxygen isotopes in Canary Island lavas (e.g. Thirlwall et al. Chem Geol 135:233–262, 1997; Day et al. Geology 37:555–558, 2009, Geochim Cosmochim Acta 74:6565–6589, 2010), these authors find variations in δ¹⁸O_ol (~4.6–6.0 ‰) beyond that measured for mantle peridotite olivine (Mattey et al. Earth Planet Sci Lett 128:231–241, 1994) and interpret this variation to reflect contributions from pyroxenite-peridotite mantle sources. Furthermore, Gurenko et al. (Contrib Mineral Petrol 162:349–363, 2011) speculate that δ¹⁸O_ol values for La Palma olivine grains measured by LF (Day et al. Geology 37:555–558, 2009, Geochim Cosmochim Acta 74:6565–6589, 2010) may be biased to low values due to the presence of altered silicate, possibly serpentine. The range in δ¹⁸O_ol values for Canary Island lavas are of importance for constraining their origin. Gurenko et al. (Contrib Mineral Petrol 162:349–363, 2011) took a subset (39 SIMS analyses from 13 grains from a single El Hierro lava; EH4) of a more extensive dataset (321 SIMS analyses from 110 grains from 16 Canary Island lavas) to suggest that δ¹⁸O_ol is weakly correlated (R ² = 0.291) with the parameter used by Gurenko et al. (Earth Planet Sci Lett 277:514–524, 2009) to describe the estimated weight fraction of pyroxenite-derived melt (Xpx). With this relationship, end-member δ¹⁸O values for HIMU-peridotite (δ¹⁸O = 5.3 ± 0.3 ‰) and depleted pyroxenite (δ¹⁸O = 5.9 ± 0.3 ‰) were defined. Although the model proposed by Gurenko et al. (Contrib Mineral Petrol 162:349–363, 2011) implicates similar pyroxenite-peridotite mantle sources to those proposed by Day et al. (Geology 37:555–558, 2009, Geochim Cosmochim Acta 74:6565–6589, 2010) and Day and Hilton (Earth Planet Sci Lett 305:226–234, 2011), there are significant differences in the predicted δ¹⁸O values of end member components in the two models. In particular, Day et al. (Geochim Cosmochim Acta 74:6565–6589, 2010) proposed a mantle source for La Palma lavas with low-δ¹⁸O (<5 ‰), rather than higher-δ¹⁸O (c.f. the HIMU-peridotite composition of Gurenko et al. in Contrib Mineral Petrol 162:349–363, 2011). Here we question the approach of using weakly correlated variations in δ¹⁸O_ol and the Xpx parameter to define mantle source oxygen isotope compositions, and provide examples of why this approach appears flawed. We also provide reasons why the LF datasets previously published for Canary Island lavas remain robust and discuss why LF and SIMS data may provide complementary information on oxygen isotope variations in ocean island basalts (OIB), despite unresolved small-scale uncertainties associated with both techniques.     

Heat capacity,entropy and phase equilibria of stishovite

The low-temperature heat capacity (C _P) of stishovite (SiO₂) synthesized with a multi-anvil device was measured over the range of 5–303 K using the heat capacity option of a physical properties measurement system (PPMS) and around ambient temperature using a differential scanning calorimeter (DSC). The entropy of stishovite at standard temperature and pressure calculated from DSC-corrected PPMS data is 24.94 J mol⁻¹ K⁻¹, which is considerably smaller (by 2.86 J mol⁻¹ K⁻¹) than that determined from adiabatic calorimetry (Holm et al. in Geochimica et Cosmochimica Acta 31:2289–2307, 1967) and about 4% larger than the recently reported value (Akaogi et al. in Am Mineral 96:1325–1330, 2011). The coesite–stishovite phase transition boundary calculated using the newly determined entropy value of stishovite agrees reasonably well with the previous experimental results by Zhang et al. (Phys Chem Miner 23:1–10, 1996). The calculated phase boundary of kyanite decomposition reaction is most comparable with the experimental study by Irifune et al. (Earth Planet Sci Lett 77:245–256, 1995) at low temperatures around 1,400 K, and the calculated slope in this temperature range is mostly consistent with that determined by in situ X-ray diffraction experiments (Ono et al. in Am Mineral 92:1624–1629, 2007).     

Comparison of aquifer vulnerability assessment techniques. Application to the Néblon river basin (Belgium)

Five different methods for assessing intrinsic aquifer vulnerability were tested in a case study and their results compared. The test area was a slightly karstified district in the Condroz region of Belgium. The basin covers about 65 km² and the karst aquifer provides a water-supply of about 28,000 m³d^-1. The methods tested were: EPIK (Doerfliger et al. 1999), DRASTIC (Aller et al. 1987), 'German method' (von Hoyer and Söfner 1998), GOD (Foster 1987) and ISIS (Civita and De Regibus 1995). The results are compared and critically examined. From the analysis, it seems that reducing the number of parameters is unsatisfactory, due to the variety of geological conditions. The various methods produce very different results at any given site. As only physically-based methods can be checked for their reliability, it is clear that future vulnerability mapping techniques must incorporate such methods.     

Computation of influence functions for automatic mining subsidence prediction

This paper presents a computer tool that automatically predicts mining subsidence using the generalized n-k-g influence function detailed in (González Nicieza et al. Int J Rock Mech Min Sci 42(3):372–387, 2005). This function depends on two physical concepts: the first is gravity, which characterizes the forces acting on the ground, and the second, the convergence of the roof and floor of the mine workings due to the stress state of the ground. The developed tool also allows other influence functions to be used to predict subsidence, namely the spatial influence function (Ramírez Oyanguren et al. 2000) and the normal-type classical (Knothe, Arch Gór Hut 1, 1952) and modified (González Nicieza et al. Bull Eng Geol Environ 66(3):319–329, 2007) time functions. Moreover, the inputting and periodic updating of data from subsidence monitoring surveys is controlled by one of the tool’s modules using a method that minimizes errors resulting from time discontinuities in landmarks measurements. In addition, when actual landmarks measurements exist, the developed tool allows calibration of the subsidence parameters, minimizing the errors between actual measurements and those obtained by prediction. The tool includes a viewer, developed using OpenGL, which enables the results of the calculations carried out to be viewed, allowing the point of view to be varied. It also includes the option of viewing and saving the results of the calculations carried out over the original topographic plane defined in the AutoCAD DXF data file format. The efficacy of the tool is demonstrated via its application to a real case of mining work carried out in a village in the Principality of Asturias, Spain.     

Recognising early Archaean mantle: a reappraisal

This paper examines 3.8 Ga peridotites from Greenland and Labrador to test claims that these samples are unmodified early Archaean mantle. Geochemical criteria were applied in which samples were compared to the mantle array in Mg/Si versus Al/Si (wt%) space, their REE patterns were compared to those of different mantle types and their chromite compositions were compared to mantle chromite compositions as expressed by their cr# and fe#. Geochemical data were used from the previously published works of Friend et al. (2002) and Bennett et al. (2002). Only two samples, from the region south of Isua satisfied all criteria, indicating that the area south of the Isua Greenstone Belt in west Greenland is a suitable place to search for early Archaean mantle. This study also confirms the observation by Friend et al. (2002) that early Archaean mantle from south of Isua is of a different character from Archaean mantle from the subcontinental lithosphere. Calculations presented here show that some mantle fragments from south of Isua experienced a lower degree of melt extraction and were probably more oxidising than early Archaean mantle preserved in the subcontinental lithosphere. Elemental concentrations of Os in early Archaean mantle are lower than the new estimate for the primitive upper mantle of Becker et al. (2006). Peridotites from the Isua greenstone belt are not mantle, but have an affinity with the layered intrusions found south of Isua.     

Reply to “Oxygen isotope heterogeneity of the mantle beneath the Canary Islands: a discussion of the paper of Gurenko et al.”

The comment by Day et al. (Contrib Mineral Petrol, 2012) (1) discusses the validity of the previously obtained oxygen isotope data for El Hierro and La Palma (Canary Island) olivines, (2) questions the approach by Gurenko et al. (Contrib Mineral Petrol 162:349–363, 2011) of using weakly correlated variations of δ¹⁸O_olivine values with X _px (proportion of pyroxenite-derived melt in the parental magma), and (3) provides reasons why oxygen isotope data by secondary ion mass spectrometry (SIMS) “offer sensitive means for detecting melt-crust interactions.” We respond these comments and report a new set of oxygen isotope measurements performed by SIMS and single-grain laser fluorination methods. These measurements confirm our previous data and conclusions and demonstrate the ability of the SIMS technique to analyze O isotopes in terrestrial samples with 2-sigma uncertainty better than ±0.25 ‰.     

Crossover of cation partitioning in olivines: a combination of ab initio and Monte Carlo study

We report studies based on a combination of ab initio electronic structure and Monte Carlo (MC) technique on the problem of cation partitioning among inequivalent octahedral sites, M1 and M2 in mixed olivines containing Mg²⁺ and Fe²⁺ ions. Our MC scheme uses interactions derived out of ab initio, density functional calculations carried out on measured crystal structure data. Our results show that there is no reversal of the preference of Fe for M1 over M2 as a function of temperature. Our findings do not agree with the experimental findings of Redfern et al. (Phys Chem Miner 27:630–637, 2000), but are in agreement with those of Heinemann et al. (Eur J Mineral 18:673–689, 2006) and Morozov et al. (Eur J Mineral 17:495–500, 2005).     

Prediction of the thermodynamic properties of metal–arsenate and metal–arsenite aqueous complexes to high temperatures and pressures and some geological consequences

The standard thermodynamic properties at 25°C, 1 bar (ΔG _f^o, ΔH _f^o, S ^o, C _P^o, V ^o, ω) and the coefficients of the revised Helgeson–Kirkham–Flowers equations of state were evaluated for several aqueous complexes formed by dissolved metals and either arsenate or arsenite ions. The guidelines of Shock and Helgeson (Geochim Cosmochim Acta 52:2009–2036, 1988) and Sverjensky et al. (Geochim Cosmochim Acta 61:1359–1412, 1997) were followed and corroborated with alternative approaches, whenever possible. The SUPCRT92 computer code was used to generate the log K of the destruction reactions of these metal–arsenate and metal–arsenite aqueous complexes at pressures and temperatures required by the EQ3/6 software package, version 7.2b. Apart from the AlAsO₄^o and FeAsO₄^o complexes, our log K at 25°C, 1 bar are in fair agreement with those of Whiting (MS Thesis, Colorado School of Mines, Golden, CO, 1992). Moreover, the equilibrium constants evaluated in this study are in good to fair agreement with those determined experimentally for the Ca–dihydroarsenate and Ca–hydroarsenate complexes at 40°C (Mironov et al., Russ J Inorg Chem 40:1690, 1995) and for Fe(III)–hydroarsenate complex at 25°C (Raposo et al., J Sol Chem 35:79–94, 2006), whereas the disagreement with the log K measured for the Ca–arsenate complex at 40°C (Mironov et al., Russ J Inorg Chem 40:1690, 1995) might be due to uncertainties in this measured value. The implications of aqueous complexing between dissolved metals and arsenate/arsenite ions were investigated for seawater, high-temperature geothermal liquids and acid mine drainage and aqueous solutions deriving from mixing of acid mine waters and surface waters. Electronic Supplementary Material The online version of this article () contains supplementary material, which is available to authorized users.     

Reply to Oczlon’s (2006) comment

The comment of Martin Oczlon contains some significant contributions to the topics discussed in the article of Huckriede et al. (Int J Earth Sci 93:414–431, 2004). Contrary to Oczlon’s comment, the central results of Huckriede et al. (Int J Earth Sci 93:414–431, 2004) are clearly different from the tectonic model of Oczlon (Geol Rundsch 83:20–31, 1994). Additionally, there is no reason for a new interpretation of the ⁴⁰K/⁴⁰Ar muscovite cooling-ages from allochthonous units.     

Coupling of oceanic and continental crust during Eocene eclogite-facies metamorphism: evidence from the Monte Rosa nappe,western Alps

High precision U–Pb geochronology of rutile from quartz–carbonate–white mica–rutile veins that are hosted within eclogite and schist of the Monte Rosa nappe, western Alps, Italy, indicate that the Monte Rosa nappe was at eclogite-facies metamorphic conditions at 42.6 ± 0.6 Ma. The sample area [Indren glacier, Furgg zone; Dal Piaz (2001) Geology of the Monte Rosa massif: historical review and personal comments. SMPM] consists of eclogite boudins that are exposed inside a south-plunging overturned synform within micaceous schist. Associated with the eclogite and schist are quartz–carbonate–white mica–rutile veins that formed in tension cracks in the eclogite and along the contact between eclogite and surrounding schist. Intrusion of the veins at about 42.6 Ma occurred at eclogite-facies metamorphic conditions (480–570°C, >1.3–1.4 GPa) based on textural relations, oxygen isotope thermometry, and geothermobarometry. The timing of eclogite-facies metamorphism in the Monte Rosa nappe determined in this study is identical to that of the Gran Paradiso nappe [Meffan-Main et al. (2004) J Metamorphic Geol 22:261–281], confirming that these two units have shared the same Alpine metamorphic history. Furthermore, the Gran Paradiso and Monte Rosa nappes underwent eclogite-facies metamorphism within the same time interval as the structurally overlying Zermatt-Saas ophiolite [∼50–40 Ma; e.g., Amato et al. (1999) Earth Planet Sci Lett 171:425–438; Mayer et al. (1999) Eur Union Geosci 10:809 (abstract); Lapen et al. (2003) Earth Planet Sci Lett 215:57–72]. The nearly identical P–T–t histories of the Gran Paradiso, Monte Rosa, and Zermatt-Saas units suggest that these units shared a common Alpine tectonic and metamorphic history. The close spatial and temporal associations between high pressure (HP) ophiolite and continental crust during Alpine orogeny indicates that the HP internal basement nappes in the western Alps may have played a key role in exhumation and preservation of the ophiolitic rocks through buoyancy-driven uplift. Coupling of oceanic and continental crust may therefore be critical in preventing permanent loss of oceanic crust to the mantle.     

Temporal Variations of Submillennial Periodicities in Sedimentary Endogenic Calcite from Lake Edward (Central Africa) During the Late Holocene

Sedimentary records of Lake Edward in Central Africa from the late Holocene era exhibit submillennial-scale periodicities in magnesium (Mg) and stable isotope compositions of endogenic calcite. Using multitaper spectral analysis, Russell et al. (Geology 31(8):677–680, 2003) detected a 725-yr cycle in the Mg data. We have analyzed the Mg data using a continuous wavelet transform and observed temporal variations in the submillennial periodicities. These temporal variations can be discerned from a time-period representation of the wavelet power spectrum by visual inspection. The multi-taper spectral analysis is based on the traditional Fourier transform, which is a purely frequency domain technique, and therefore cannot detect temporal variability of the spectrum, if any. In contrast, wavelet analysis offers a spectral-temporal approach by which both the dominant periodicities and their time variations can be identified. In this regard, the results of our wavelet analysis extend those of Russell et al. (Geology 31(8):677–680, 2003). Our analysis reveals dominant periodicities around the 785-yr and 660-yr cycles, but these cycles persist over different time spans within the late Holocene era. The 725-yr period identified by Russell et al. (Geology 31(8):677–680, 2003) with multitaper spectral analysis is very close to the average of the periods of these two cycles. For the purpose of accurately reconstructing the climate history in Central Africa using Mg as a proxy, it would be important to take into consideration the temporal variations of the submillennial periodicities.     

Experimental Validation of an Method for In Situ Estimation of Hydraulic Conductivity of Water Treatment Granular Materials

Domestic wastewater-treatment system is today a widely held technique. In order to evaluate the efficiency of these systems, it is necessary to determinate the in situ hydraulic conductivity of the water-treatment granular materials constituting them. The in situ measurement of the hydraulic conductivity of soils has proven to be imprecise, take a long time. Empirical equations based on the physical properties of soil have been proposed to overcome these difficulties. In this context, the originality of this paper is to propose an in situ method to obtain reliable input parameters for the predictive equations of Chapuis (Can Geotech J 41(5): 787–795, 2004) and Carrier (J Geotech Geoenviron Eng 129(11): 1054–1056, 2003) by using both a penetrometer and a geoendoscope. This method is described in the first part of this paper. Then, the validation of the method based on laboratory tests performed under controlled conditions for three kinds of soils is presented. Hydraulic conductivity obtained when applying the method is compared to that measured by a Darcy permeameter. The difference between these two hydraulic conductivities is less than 25%. Finally, the precision of the results is discussed.     

Basanite–nephelinite suite from early Kilauea: carbonated melts of phlogopite–garnet peridotite at Hawaii’s leading magmatic edge

A basanite–nephelinite glass suite from early submarine Kilauea defines a continuous compositional array marked by increasing concentrations of incompatible components with decreasing SiO₂, MgO, and Al₂O₃. Like peripheral and post-shield strongly alkalic Hawaiian localities (Clague et al. in J Volcanol Geotherm Res 151:279–307, 2006; Dixon et al. in J Pet 38:911–939, 1997), the early Kilauea basanite–nephelinite glasses are interpreted as olivine fractionation products from primary magnesian alkalic liquids. For early Kilauea, these were saturated with a garnet–phlogopite–sulfide peridotite assemblage, with elevated dissolved CO₂ contents responsible for the liquids’ distinctly low-SiO₂ concentrations. Reconstructed primitive liquids for early Kilauea and other Hawaiian strongly alkalic localities are similar to experimental 3 GPa low-degree melts of moderately carbonated garnet lherzolite, and estimated parent magma temperatures of 1,350–1,400°C (olivine–liquid geothermometry) match the ambient upper mantle geotherm shortly beneath the base of the lithosphere. The ~3 GPa source regions were too hot for stable crystalline carbonate and may have consisted of ambient upper mantle peridotite containing interstitial carbonate–silicate or carbonatitic liquid, possibly (Dixon et al. in Geochem Geophys Geosyst 9(9):Q09005, 2008), although not necessarily, from the Hawaiian mantle plume. Carbonate-enriched domains were particularly susceptible to further melting upon modest decompression during upward lithospheric flexure beneath the advancing Hawaiian Arch, or by conductive heating or upward drag by the Hawaiian mantle plume. The early Kilauea basanite–nephelinite suite has a HIMU-influenced isotopic character unlike other Hawaiian magmas (Shimizu et al. in EOS Tran Amer Geophys Union 82(47): abstr V12B-0962, 2001; Shimizu et al. in Geochim Cosmochim Acta 66(15A):710, 2002) but consistent with oceanic carbonatite involvement (Hoernle et al. in Contrib Mineral Petrol 142:520–542, 2002). It may represent the melting products of a fertile domain in the ambient upper mantle impinged upon and perturbed by the sustained plume source that feeds later shield-stage magmatism.     

Arching within hydraulic fill stopes

Arching is a well known phenomenon, which effects stress developments which were investigated and compared using analytical and numerical solutions. Marston’s (1930) solution was extended to a generalised 3-dimensional rectangular stope and later modified for square and circular stopes for comparison with FLAC results. Aubertin et al. (2003) & Li et al. (2003) models were improved significantly by placing the backfill within narrow stopes as lifts or layers in numerical modelling where the normal stress variation with depth were found to be more realistic. The FLAC results were compared with analytical solutions which were developed by previous researchers and modified by the authors to evaluate the arching effects in backfilled placed in narrow and circular stopes. It appeared from the investigation herein that δ = 0.67 ϕ and K = K _o condition gives a very close match with the numerical model solutions obtained from FLAC. Many laboratory tests were conducted to find out friction angles for four Australian mines, which were between 30 and 49 degrees.     

The quantitative analysis of OH in vesuvianite: a polarized FTIR and SIMS study

A well-characterized suite of vesuvianite samples from the volcanic ejecta (skarn or syenites) from Latium (Italy) was studied by single-crystal, polarized radiation, Fourier-transform infrared (FTIR) spectroscopy and secondary-ion mass-spectrometry (SIMS). OH-stretching FTIR spectra consist of a rather well-defined triplet of broad bands at higher-frequency (3,700–3,300 cm^–1) and a very broad composite absorption below 3,300 cm^–1. Measurements with E//c or Ec show that all bands are strongly polarized with maximum absorption for E//c. They are in agreement with previous band assignments (Groat et al. Can Mineral 33:609, 1995) to the two O(11)–H(1) and O(10)–H(2) groups in the structure. Pleochroic measurements with changing direction of the E vector of the incident radiation show that the orientation of the O(11)–H(1) dipole is OHc~35°, in excellent agreement with the neutron data of Lager et al. (Can Mineral 37:763, 1999). A SIMS-based calibration curve at ~10% rel. accuracy has been worked out and used as reference for the quantitative analysis of H₂O in vesuvianite by FTIR. Based on previous SIMS results for silicate minerals (Ottolini and Hawthorne in J Anal At Spectrom 16:1266, 2001; Ottolini et al. in Am Mineral 87:1477, 2002) the SiO₂ and FeO content of the matrix were assumed as the major factors to be considered at a first approximation in the selection of the standards for H. The lack of vesuvianite standards for quantitative SIMS analysis of H₂O has been here overcome by selecting low-silica elbaite crystals (Ottolini et al. in Am Mineral 87:1477, 2002). The resulting integrated molar absorption FTIR coefficient for vesuvianite is _i=100.000±2.000 l mol^–1 cm^–2. SIMS data for Li, B, F, Sr, Y, Be, Ba REE, U and Th are also provided in the paper.     

Discrete-Element Computation of Averaged Tensorial Fields in Sand Piles Consisting of Polygonal Particles

This work is a contribution to the understanding of the mechanical properties of non-cohesive granular materials in the presence of friction and a continuation of our previous work (Roul et al. 2010) on numerical investigation of the macroscopic mechanical properties of sand piles. Besides previous numerical results obtained for sand piles that were poured from a localized source (“point source”), we here consider sand piles that were built by adopting a “line source” or “raining procedure”. Simulations were carried out in two-dimensional systems with soft convex polygonal particles, using the discrete element method (DEM). First, we focus on computing the macroscopic continuum quantities of the resulting symmetric sand piles. We then show how the construction history of the sand piles affects their mechanical properties including strain, fabric, volume fraction, and stress distributions; we also show how the latter are affected by the shape of the particles. Finally, stress tensors are studied for asymmetric sand piles, where the particles are dropped from either a point source or a line source. We find that the behaviour of stress distribution at the bottom of an asymmetric sand pile is qualitatively the same as that obtained from an analytical solution by Didwania and co-workers (Proc R Soc Lond A 456:2569–2588, 2000).     

On the Use of Skempton’s Compression Index Equation

In this study, an alternate approach to establish the e-log p relationships for clayey soils within a vertical pressure range of 10–1,000 kPa is discussed. Skempton’s compression index equation correlating the liquid limit, w _L, and the compression index, C _c, and the reported equation correlating the void ratio at liquid limit, e _L, and the void ratio at a vertical pressure of 100 kPa, e ₁₀₀, by Burland (1990), were used to establish the e-log p relationships for several reconstituted normally consolidated clayey soils. Consolidation test results of 13 clayey soils covering a sufficiently wide range of liquid limit were selected from the literature. Also, consolidation tests were carried out on two highly expansive soils in this study. A comparison of the experimental consolidation test results with the calculated e-log p relationships in the current study indicated that in general, the agreements between the calculated relationships and the experimental results are good. The agreements were found to be slightly better for soils with liquid limits less than about 70%. A comparison of the calculated e-log p relationships in the current study with that determined following methods suggested by Nagaraj and Srinivasa Murthy (1983) and Burland (1990) showed that all the three methods yielded very similar results for soils with liquid limit less than 70%. For soils with liquid limits greater than 70%, the difference between the e-log p relationships calculated in this study and that following Burland (1990)’s method was insignificant, whereas Nagaraj and Srinivasa Murthy (1983)’s method slightly over-predicted the void ratios at larger vertical stresses.     

Morphological signatures of fault lines in an earthquake prone zone of southern Baromura hill, north-east India: a multi source approach for spatial data analysis. A critical review

In a recent work, Dey et al. (Environ Earth Sci 59:353–361, 2009) presented some new observations on the southern part of one of the anticlinal ridges of Tripura, viz. the Baromura range. The work incorporated a number of irregularities and misinterpretations that need to be addressed to avoid future confusion. The present article critically reviews Dey et al.’s paper to bring out its inaccuracies.