Elia Scudiero, Elia Scudiero, Michael P. Schmidt
et al.
In specialty crops, water and nutrient management may be optimized using accurate, high-resolution soil maps, especially in resource-constrained farmland, such as California. We evaluated the use of soil apparent electrical conductivity (ECa) and gamma-ray spectrometry (GRS) to map particle size fraction across three micro-irrigated non-saline citrus orchards in California. Our research showed that ECa was a reliable predictor of soil texture, particularly sand and silt contents, with Pearson correlation coefficients (r) as high as -0.92 and 0.94, respectively, at the field level. Locally-adjusted analysis of covariance (ANOCOVA) regressions using ECa data returned accurate sand, silt, and clay content estimations with mean absolute errors (MAE) below 0.06, even when calibrated with a limited dataset (n=5 per field). On the other hand, we observed mixed results with GRS. We observed negative correlations between GRS total counts and sand content over the entire dataset (r = -0.55). However, one site (Strathmore) showed a field-scale positive correlation (r = 0.88). Clay content significantly correlated with gamma-ray total counts (TC) over the entire dataset (r = 0.37) but not at the field scale. Additional soil data analyses using GRS radionuclide ratios and soil laboratory analyses using diffuse reflectance infrared Fourier transform spectroscopy and acid ammonium oxalate extractable elements indicated unique geochemical and mineralogical characteristics in Strathmore, suggesting that factors such as soil mineralogy influenced the GRS measurements. This inconsistency prevented the development of a multi-field GRS-based soil texture ANOCOVA model. These findings confirm that ECa is highly effective for soil texture mapping in non-saline soils using linear modeling, while GRS may require field-specific calibration due to variations in local mineralogy. Integrating multi-sensor data is a viable means for reducing ground-truthing requirements and related costs, and improving the quality and accuracy of soil maps in agriculture.
Suffusion is the process defined as the migration of relatively small soil particles through the pores of a soil matrix composed of relatively large particles, driven by substantial hydrodynamic forces and weak attraction energies. This study investigates the influence of flow direction (upward and downward) on suffusion induced by interaction energies in sand-clay mixtures under both saturated and unsaturated conditions. The impact of clay mineralogy (kaolinite, illite, and montmorillonite), sand-grain size, and ionic concentration (IC) gradient were discussed based on the observed breakthrough curves (BTCs) and relative saturation rate (Sr) during injection (particularly for unsaturated conditions). Under saturated conditions, higher susceptibility to suffusion was observed in sand-kaolinite and sand-illite mixtures under downward flow compared to upward flow, whereas the suffusion of montmorillonite was more significant under upward flow than under downward flow. In contrast, for unsaturated conditions, more substantial suffusion of kaolinite and illite particles occurred under upward flow compared to downward flow, whereas the opposite trend was observed in sand-montmorillonite mixtures. In addition, the impact of sand-grain size (or the size ratio between sand and clay) on the suffusion of kaolinite and illite under unsaturated conditions suggests a reduced size ratio that leads to relatively significant suffusion under downward flow compared to upward flow. The findings presented in this study contribute to a comprehensive understanding of the influence of flow direction on suffusion in sand-clay mixtures under both saturated and unsaturated conditions.
Engineering geology. Rock mechanics. Soil mechanics. Underground construction
Mamta Kumari, Rajkishore Kumar, Rajeev Padbhushan
et al.
Abstract Intensive mono-cropping and abiotic stresses in the tea (Camellia sinensis L.) growing areas caused soil nutrient degradation and low crop productivity. Site-specific management requires understanding the mechanism of the geographical setting and its variability that plays a pivotal role in the growth and quality of tea crops. The present study targeted the tea-growing soils of India to determine their nutrient status as well as profile mineralogical composition to establish soil and land use management strategies for the region. Collected surface soil samples were analyzed for soil parameters. Soil profile sampling was done for clay mineral characterization of the area by using X-ray diffraction method. The Geo-statistical approach was used in this study—A method for analyzing geographical distribution and variability that is evolved from classical statistics. Study revealed that soil reaction was acidic to normal (3.95–6.80); non-saline (0.05–0.47 dS m−1) and soil organic carbon (SOC) range was low to medium (0.06–0.62%). Macronutrients, available nitrogen (N) status was low (62.5–237 kg ha−1), whereas available phosphorus (P) (3.0–59 kg ha−1) and potassium (K) (100–403 kg ha−1) levels were low to high. Micronutrients, iron (Fe) and manganese (Mn) was deficient to sufficient, whereas, zinc (Zn) and copper (Cu) were sufficient in range. Descriptive statistics and geostatistical methods of the analysis revealed that soil pH, electrical conductivity (ECe), SOC, available K, Fe and Mn were strongly spatial dependent, whereas N, Zn, and Cu, were moderately spatial dependent, caused by both random factors as well as structural factors (soil texture, soil type, fertilization, and local ecological restoration management). Clay mineralogical characterization of soil profile (surface and subsurface) revealed the dominance of illite clay minerals followed by kaolinite and smectite and less concentration of chlorite and quartz showing greater forms of K presence in the soils. Therefore, the recommendation is that, application of balance fertilizers with combination of inorganic (macro and micronutrients) and organic sources of nutrients might be beneficial for sustainable tea production in this region. It will ultimately improve soil fertility, enhance tea yield and support the socio-economic well-being of tea growers.
Co and Ni minerals are described in ores of the Mikheevskoe porphyry copper deposit (South Urals, Russia). Minerals of the cobaltite–gersdorfte series (CoAsS–NiAsS), violarite (FeNi2S4), millerite (NiS), pentlandite (Ni5.5Fe3.4)8.9S8.0 and melonite (NiTe2) are identifed. They overgrow pyrite, chalcopyrite and bornite and belong to late low-temperature assemblages. Cobalt and Ni are also incorporated in pyrite. The latter, being the most widespread mineral of the deposit, is a major carrier of these metals. The variability of Co and Ni minerals is determined by the presence of serpentinites, which replaced ultramafc rocks.
Shavekina Alfiia, Bortnikova Svetlana, Gaskova Olga
et al.
The paper presents the results of studies of the composition of secondary Fe, Pb, Cu minerals, formed in contrasting physico-chemical conditions of the stockpiled tailings from the enrichment of Salair barite-polymetallic ores (West Siberia, Russia). The complex mineral composition of ores containing pyrite, chalcopyrite, sphalerite, galena, fahlore, and long-term chemical weathering contributed to the formation of monomineral and zonal secondary rims and fillings of the intergranular space, which were identified using modern research methods. Plumbojarosite, anglesite, cerussite, and iron hydroxides are predominant among them; pyromorphite, hinsdalite, and covellite are less abundant. Thermodynamic modeling was used to solve the inverse problem of restoring the composition of solutions that led to a sequence change in associations of secondary minerals. The observed processes are determined not only by chemical interaction, but also by electrochemical reactions in the systems under consideration, where various mineral components act as galvanic couples. These two processes, combined with the physicochemical parameters of the environment (pH, Eh, ionic composition of solutions), lead to stepwise or incomplete oxidation of the original minerals, followed by selective deposition of the secondary compounds.
Abstracts: Steam injection is commonly used for production of viscous crude oil. Reservoir rock often contains clay minerals. Reactive nature of steam and clay minerals may lead to formation damage. This work investigates oil recovery and changes in petrophysical properties as a function of the mineralogy. Sandpacks with quartz, calcite, feldspar, kaolinite, smectite, and illite were prepared for steam injection experiments. Permeability of the steamed sandpacks was determined using coreflood experiments. Chemical composition of the produced aqueous samples was determined using ICP-OES (inductively coupled plasma-optical emission spectroscopy). Morphology of the rock samples was studied using SEM-EDS (scanning electron microscope-energy dispersive X-ray spectroscopy). Mineralogy and elemental content of the solid samples were determined using XRD (X-ray diffraction) analysis and XRF (X-ray fluorescence) respectively. It was found that aqueous phase samples produced from clay-rich sandpacks tend to have higher pH than samples produced from samples without clay minerals. Oil recovery factors for 100% quartz case was determined to be 65 wt%. Calcite- and feldspar-rich sandpacks produced 56 and 61 wt% of oil respectively. Sandpacks with clay fractions have shown the lowest oil recovery – 39, 29, and 28 wt% for kaolinite-, smectite-, and illite-rich samples respectively. Mineral dissolution and precipitation were the dominant damaging mechanism for quartz and calcite cases. Feldspar-rich sandpack demonstrated signs of structural destruction of the mineral and fines release. Kaolinite's effect on oil recovery was found to be associated with fines migration. Smectite hydration and swelling in presence of steam was the dominant formation damage effect on the oil production. Steam interaction with illite-rich sandpack caused formation of amorphous silica. This paper presents oil recovery factors as a function of injected pore volume (PV) of steam for sandpacks of different mineralogy. Obtained results characterize petrophysical changes caused by steam interaction with minerals in presence of oil. This data provides insights into effects of steam on minerals with different structures and properties.
Oils, fats, and waxes, Petroleum refining. Petroleum products
Mineral physics emerged as an independent discipline of Earth sciences in the middle of the 20th century, drawing together geophysics and mineralogy. Using the principles of condensed matter physics and solid-state chemistry, it focuses on exploring how physical properties of minerals depend on atomic structure. With the advent of new experimental tools (e.g., automated X-ray diffractometers, electron microscopes, various spectrometric techniques, digital computers and synchrotron X-radiation sources) in the past 70 years, geophysicists and mineralogists began to talk with one another.
Vassily Mikhaltsevitch, Maxim Lebedev, Rafael Chavez
et al.
In presented paper, we describe the technical and physical aspects of the application of a low-frequency (LF) apparatus based on a longitudinal type of forced oscillations. In particular, we investigate the influence of the strain gauge position on a tested sample on measurement results, we also examine the creep effect associated with the mineralogy of rocks, as well as the dispersion and attenuation in a liquid-saturated rock sample caused by the presence of the volume of pore fluid exterior to the sample (dead volume). The effect of the position of the strain gauges is investigated using a cylindrical acrylic sample and two pairs of strain gauges fixed in the middle and at one of the sample ends under a uniaxial pressure of 15 MPa. The obtained results demonstrate that elastic and anelastic parameters of the tested sample are independent from the location of the strain gauges. The impact of the creep phenomenon on elastic moduli was studied using three room-dry samples of Savonnieres limestone, Berea sandstone and Eagle Ford shale. The measurements were conducted for 120 h at a frequency of 2 Hz under a uniaxial pressure of 10 MPa and demonstrated that the LF moduli of all rocks were noticeably reduced with time. The effect of dead volume was investigated at seismic frequencies using limestone saturated with n-decane. It was found that the Young’s and bulk moduli exhibit strong dispersion at frequencies above 10 Hz if the dead volume is close to or greater than the pore volume of the sample. We also found that the characteristic frequency of dispersion corresponding to the attenuation peak is independent of the size of the dead volume and determined only by the physical parameters of the sample and pore fluid. We present also the results of the Young’s modulus and attenuation measurements conducted at seismic frequencies on vertical and horizontal shale samples saturated with water. It was shown that the relationship between the extensional attenuation and the Young’s modulus dispersion observed in the samples saturated at a relative humidity of 97.5% is consistent with the Kramers–Kronig relation.
The paper discusses the physico-chemical formation conditions of minerals-phenocrysts in basaltic complexes, which host massive sulfide deposits of the Urals and Siberia. It is found as a result of study of melt inclusions that clinopyroxene from basalts of the Valentorka (North Urals) and Kyzyl-Tashtyg (South Siberia) deposits crystallized from melts with similar temperature (1165–1130 and 1210–1085 °С, respectively) and chemical parameters. In both cases, the compositions of basalt-andesite magmas (with features of igneous island arc and back-arc basin systems) evolved with a decrease in FeO, MgO, and CaO contents and increase in K2 O and SiO2 contents. Modeling, which is based on the compositions of inclusions and clinopyroxene, showed that minerals-phenocrysts crystallized from intermediate magma chambers of different depth, the parameters of which are consistent with each other and with data on present-day suprasubduction magmatism: Valentorka deposit – 33–27, 23–13, and 10–3 km, 1185–1090 °C; Kyzyl-Tashtyg deposit – 27–20, 15.0–6.7, and 5.0–1.7 km, 1215–1105 °С. Calculations using compositions of melt inclusions show a consistent change of melts from basalts to rhyolites, indicating that the combination of contrasting volcanic complexes of the deposits studied are a result of the evolution of initial basaltic magmas during their uplift to the upper crustal horizons. Our studies of rocks, clinopyroxene and melt inclusions indicate that the basaltic complexes of the Valentorka and Kyzyl-Tashtyg deposits formed in an ancient suprasubduction island arc – back-arc basin system.
Mishrif Formation (Late Cenomanian) has been studied in four oilfields in southern Iraq, and studied samples were examined by mineralogy and geochemistry analysis using XRF and XRD techniques.
The mineralogical study reveals that dolomite and calcite are the main minerals in the rock formation in studied oil fields, whereas quartz and clay minerals (kaolinite, montmorillonite and illite) represent secondary minerals composition. For geochemical classification of Mishrif rock, Ca/Mg ratio was applied and this reveals that Calcitic Limestone is a major type in studied samples.
The paleo - salinity has been examined by using Ca/Mg and Mg/Ca ratios and they referred to moderate salinity during deposition. Mg/Ca and Mn/Ca ratios have been applied to measure paleo-temperature, so infer a moderate paleo-temperature for Mishrif Formation in studied samples. Based on the comparison between low Sr/Ca and the relatively high Ca/Mg ratios, infer that a dolomitization process played the main role among diagenesis processes.
Ventini Roberta, Flora Alessandro, Lirer Stefania
et al.
As well known, rockfill behaviour is strongly influenced by both intrinsic (mineralogy and size of particles, grain shapes, soil grading etc.) and state parameters (relative density, stress state, relative humidity). To investigate their mechanical response to stresses and relative humidity (RH) loadings, a large size triaxial device (H = 410 mm, D = 200 mm) has been developed at the University of Naples Federico II (Italy), including modifications required to impose partially saturated conditions in the specimen by means of the vapour equilibrium technique. In order to evaluate local axial and radial strains and global volumetric strains in partially saturated conditions, a magnetic shape detector device has been designed and installed. The accuracy of this system has been evaluated in some isotropic compression triaxial tests on compacted sandy-gravel specimens. The experimental data clearly show the effectiveness of the magnetic system in the measurement of axial displacements while the measurement in radial direction appear to be strongly affected by the non-linearity of the complex magnetic field generated during the test and requires further checking tests.
Rafael Schäffer, Ingo Sass, Claus-Dieter Heldmann
et al.
A borehole heat exchanger array was installed in an Alpine karst aquifer for the first time in Europe. It is composed of nine 400 m deep boreholes in the dolomitic marble of the Hochstegen Formation. New approaches were developed for this unprecedented application and potential risks were checked throughout the sinking of the initial exploratory wellbore. As Finkenberg is located in a tourist area, drilling operations had to be executed within only a few weeks. Several springs downstream from the drilling site are sources of drinking water and tap water supply. Given that the degree and distribution of the Hochstegen Formation karstification was unknown, a spring monitoring program was mandatory in order to obtain drilling permission from public authorities. A practicable and affordable spring monitoring program including several physical and chemical parameters was developed and implemented to document the potential impact of the drilling activities on the spring water. A temporary and locally limited impact of the drilling works on groundwater quality was detected by turbidity measurements. This paper reports the implementation of geothermal drilling in a karst aquifer with a focus on karstification as well as planning, implementation and the results of the spring monitoring program. Such a program can be recommended for comparable projects or questions, adapting the characteristic parameters to be collected and the measurement intervals in consultation with the relevant authorities. It might also increase the chances of gaining approval for geothermal projects in karst and could enhance public acceptance.
Key words: Pneumatic down hole hammer drilling, Borehole heat exchanger, Groundwater monitoring, Turbidity, Hochstegen Formation.
Geotermalno vrtanje v alpskem kraškem vodonosniku in njegov vpliv na dolvodne izvire - študija primera Finkenberg, Tirolska, Avstrija
V alpskem kraškem vodonosniku je bilo prvič v Evropi vzpostavljeno polje geosond. Vključuje devet 400 m globokih vrtin, izvrtanih v dolomitnem marmorju Hochstegenove formacije. Razvili smo nove pristope za to aplikacijo brez primere in potrdili morebitna tveganja v času potopitve prvotne raziskovalne vrtine. Ker je študijsko območje Finkenberg na turističnem območju, je bilo treba opraviti vrtanje v samo nekaj tednih. Več izvirov od mesta vrtanja so viri oskrbe s pitno vodo. Glede na to, da stopnja in porazdelitev zakraselosti Hochstegenove formacije nista bili znani, je bilo treba za pridobitev dovoljenja za vrtanje nujno opazovati izvire. Da bi dokumentirali vpliv vrtanja na izvirsko vodo, je bilo pri spremljanju izvirov treba upoštevati več fizikalnih in kemijskih parametrov. Zaznali smo občasen in lokalno omejen vpliv vrtanja na kakovost podzemne vode. V prispevku smo predstavili izvajanje geotermalnega vrtanja v kraškem vodonosniku s poudarkom na identifikaciji zakraselosti ter načrtovanju ter na izvedbi in spremljanju kakovosti voda na izviru. Tak program se lahko uporabi pri primerljivih projektih ali iskanju odgovorov na podobna vprašanja s prilagojenim programom opazovanih parametrov in intervalov merjenja. Prav tako bi lahko povečal možnosti za pridobitev soglasja za geotermalne projekte na krasu in povečal ozaveščenost javnosti.
Ključne besede: vrtanje s pnevmatskim kladivom, geosonda, spremljanje podzemne vode, motnost, Hochstegenova formacija.
A borehole heat exchanger array was installed in an Alpinekarst aquifer for the first time in Europe. It is composed of nine400 m deep boreholes in the dolomitic marble of the HochstegenFormation. New approaches were developed for thisunprecedented application and potential risks were checkedthroughout the sinking of the initial exploratory wellbore. AsFinkenberg is located in a tourist area, drilling operations hadto be executed within only a few weeks. Several springs downstreamfrom the drilling site are sources of drinking water andtap water supply. Given that the degree and distribution of theHochstegen Formation karstification was unknown, a springmonitoring program was mandatory in order to obtain drillingpermission from public authorities. A practicable and affordablespring monitoring program including several physical andchemical parameters was developed and implemented to documentthe potential impact of the drilling activities on the springwater. A temporary and locally limited impact of the drillingworks on groundwater quality was detected by turbidity measurements.This paper reports the implementation of geothermaldrilling in a karst aquifer with a focus on karstification aswell as planning, implementation and the results of the springmonitoring program. Such a program can be recommended forcomparable projects or questions, adapting the characteristic
Biomineralised hard parts form the most important physical fossil record of past
environmental conditions. However, living organisms are not in thermodynamic
equilibrium with their environment and create local chemical compartments
within their bodies where physiologic processes such as biomineralisation
take place. In generating their mineralised hard parts, most marine
invertebrates produce metastable aragonite rather than the stable polymorph
of CaCO<sub>3</sub>, calcite. After death of the organism the physiological
conditions, which were present during
biomineralisation, are not sustained any further and the system moves toward
inorganic equilibrium with the surrounding inorganic geological system. Thus,
during diagenesis the original biogenic structure of aragonitic tissue
disappears and is replaced by inorganic structural features.
<br><br>
In order to understand the diagenetic replacement of biogenic aragonite to
non-biogenic calcite, we subjected <i>Arctica islandica</i> mollusc shells
to hydrothermal alteration experiments. Experimental conditions were between
100 and 175 °C, with the main focus on 100 and 175 °C,
reaction durations between 1 and 84 days, and alteration fluids simulating
meteoric and burial waters, respectively. Detailed microstructural and
geochemical data were collected for samples altered at 100 °C (and
at 0.1 MPa pressure) for 28 days and for samples altered at 175 °C
(and at 0.9 MPa pressure) for 7 and 84 days. During hydrothermal alteration
at 100 °C for 28 days most but not the entire biopolymer matrix was
destroyed, while shell aragonite and its characteristic microstructure was
largely preserved. In all experiments up to 174 °C, there are no
signs of a replacement reaction of shell aragonite to calcite in X-ray
diffraction bulk analysis. At 175 °C the replacement reaction
started after a dormant time of 4 days, and the original shell microstructure
was almost completely overprinted by the aragonite to calcite replacement
reaction after 10 days. Newly formed calcite nucleated at locations which
were in contact with the fluid, at the shell surface, in the open pore
system, and along growth lines. In the experiments with fluids simulating
meteoric water, calcite crystals reached sizes up to 200 µm, while
in the experiments with Mg-containing fluids the calcite crystals reached
sizes up to 1 mm after 7 days of alteration. Aragonite is metastable at all
applied conditions. Only a small bulk thermodynamic driving force exists for
the transition to calcite. We attribute the sluggish replacement reaction to
the inhibition of calcite nucleation in the temperature window from ca. 50 to
ca. 170 °C or, additionally, to the presence of magnesium.
Correspondingly, in Mg<sup>2+</sup>-bearing solutions the newly formed calcite
crystals are larger than in Mg<sup>2+</sup>-free solutions. Overall, the
aragonite–calcite transition occurs via an interface-coupled
dissolution–reprecipitation mechanism, which preserves morphologies down to
the sub-micrometre scale and induces porosity in the newly formed phase. The
absence of aragonite replacement by calcite at temperatures lower than
175 °C contributes to explaining why aragonitic or bimineralic
shells and skeletons have a good potential of preservation and a complete
fossil record.
The subject of investigations were rodingites, whose outcrops were recently found inTaukha terrane of the Sikhote-Alin. The contents of the rock-forming oxides in rodingites were determined using the methods of chemical analysis as well as the gravimetry (SiO2, H2O, and Loi) and atomic-emission spectrometry with the induction-bound plasma at the iCAP 6500Duo spectrometer (Thermo Scientific Corporation, USA) (other oxides). The contents of the secondary elements were determined with the method of mass-spectrometry with the induction-bound plasma at the Agielent 7500 с spectrometer (Agielent Technologies, USA). Analyses of minerals were done using the JXA8100 microanalyser with three wave spectrometers and the INCAx-sight power-dispersion spectrometer. The contents of precious metals were determined with the atomic-absorption method. The paper presents the results of investigations of the geological conditions of occurrence, petrochemistry, geochemistry, and mineralogy of rodingites and the Au-Pd-Pt mineralization in them. The rock-forming minerals of rodingites of the Sikhote-Alin’ are pyroxene, garnet, vesuvian, epidote, prehnite, amphibole, chlorite, plagioclase, potassium-feldspar, apatite, zircon, titanite, and others. In rodingites of the Sikhote-Alin’ there were found the relatively high contents of Au, Ag, Pt, and Pd and the typical of such rocks “copper gold” and native forms and intermetallic compounds of diverse metals. The investigations carried out allowed the substantiation of the conclusion about the genetic relation of rodingites with the Paleocene ultrabasic-intermediate and alkaline-subalkaline complex of the Sikhote-Alin’. The rodingites were formed by metasomatic way on the basic and ultrabasic rocks of the vent and intrusive phases. They have preserved some geochemical characteristics of protoliths, in which they clearly differ from skarns with the boron, polymetal, and iron mineralization of the Dalnegorsky and Olginsky ore districts and from the contact-metamorphosed Triassic metal-bearing sediments of the Sikhote-Alin’. The Paleocene magmatic complex of the Sikhote-Alin’ is of a special interest because with it the precious-metal mineralization is genetically related that is localized not only in rodingites but also in other rocks of the Paleocene explosive structures and in the alluvium of the springs draining them.
Engineering geology. Rock mechanics. Soil mechanics. Underground construction
In the area of Denmark Strait (~66° N), the two modes of the North
Atlantic Oscillation (NAO) and Arctic Oscillation (AO) are expressed in
changes of the northward flux of Atlantic water and the southward advection
of polar water in the East Iceland current. Proxies from marine cores along
an environmental gradient from extensive to little or no drift ice, capture
low frequency variations over the last 2000 cal yr BP. Key proxies
are the weight% of calcite, a measure of surface water stratification and
nutrient supply, the weight% of quartz, a measure of drift ice transport,
and grain size. Records from Nansen and Kangerlussuaq fjords show variable
ice-rafted debris (IRD) records but have distinct mineralogy associated with
differences in the fjord catchment bedrock. A comparison between cores on
either side of the Denmark Strait (MD99-2322 and MD99-2269) show a remarkable
millennial-scale similarity in the trends of the weight% of calcite with a
trough reached during the Little Ice Age. However, the quartz records from
these two sites are quite different. The calcite records from the Denmark Strait
parallel the 2000 yr Arctic summer-temperature reconstructions; analysis of
the detrended calcite and quartz data reveal significant multi-decadal–century periodicities superimposed on a major environmental shift occurring
ca. 1450 AD.