Basaltic Environment Research Articles

Vertical Electrical Sounding Technique as an Efficient and Rapid Tool for Groundwater Investigation in a Basaltic Environment at Kodana Station for the Shami goats. Case Study from Southern Syria

Geoelectrical survey was conducted by using vertical electrical sounding technique (VES) with adapting Schlumberger configuration, to locate and drill a borehole for groundwater extraction in the Kodana station for the Shami goats, Southern Syria. An integrated approach is proposed to increase the efficacy of the VES technique and to reduce the uncertainties and the high failures in locating and drilling a successful groundwater borehole. The approach is essentially based on analyzing the Dar-Zarrouk (D-Z) parameters with constraining several conditions to obtain the optimum hydro-geophysical model.The 1D inversion quantitative interpretation of twelve VES sounding points and the (D-Z) parameters allowed the characterization of the study area in terms of depth and the Neogene pyroclastic basalt aquifer. The result showed that VES point (V6) has the optimum and favorable properties for drilling a successful borehole in the area. The V6 has GPS coordinates of E: 3589614, N: 3301961 and Z: 770835m. The Neogene (fractured pyroclastic layer with rocks of basaltic composition) aquifer at this V6 point is characterized by a thickness (h) of 217m, a resistivity (ρ) of 227Ωm, a transverse resistance (R) of 49259 Ωm2, and an anisotropy parameter (λ) of 1.15. The advantages of the proposed approach are well proven and documented, in comparing with other techniques that require the combination of VES technique with other available geophysical techniques. The VES technique within the proposed approach is therefore recommended to be easily applied for groundwater investigations, and locating the suitable positions for drilling boreholes in similar worldwide basaltic environments.

Spectroscopic comparisons of two different terrestrial basaltic environments: Exploring the correlation between nitrogen compounds and biomolecular signatures

Life detection in the solar system relies on the unambiguous identification of signatures of life and habitability. Organic molecules are essential to life as we know it, and yet many organic compounds are ubiquitous in the solar system and can be synthesized abiotically; thus, their presence alone is not indicative of life. On Earth, chemical signatures of life's processes are often left behind in minerals through the biologically induced formation of secondary minerals or intermediary organic complexes. In natural rocks biomolecules and organic species often co-occur with minerals, and their overlapping peaks can create difficulties in interpretation. In the process of identifying the minerals and organic species in our basaltic samples we noticed signatures for cyanates co-occurring with organic molecules. Cyanates are an overlooked group of nitrogen compounds in which C is bonded to N (e.g., OCN− or SCN−) that often co-occur with urea and ammonium in environments where microorganisms are present. These compounds are common in many terrestrial and oceanic environments and play an important role in biogeochemical nitrogen cycling. In natural systems, these compounds form as the result of multiple biogeochemical pathways, often from the interaction of microbes with a chemically active environment. These interactions leave behind signatures in the form biotic breakdown products such as urea or ammonium and organic reaction byproducts that are observable with spectroscopic methods. To explore these relationships, we used field-portable Raman spectrometers and laboratory micro-Raman imaging to characterize and compare samples collected from two different terrestrial basaltic environments, a lava tube on Mauna Loa, Hawaii, dominated by the precipitation of sulfate minerals and a geothermal stream at Hveragil, Iceland dominated by the precipitation of carbonate minerals. The Raman (RS) measurements were complemented by laser induced breakdown spectroscopy (LIBS), Long-wave Infrared (IR) LIBS, with the addition of gas chromatograph mass spectrometry (GC–MS) and inductively coupled plasma-mass spectrometry (ICP-MS) to identify cyanate compounds, biomolecules, and other nitrogenous compounds related to the breakdown or production of cyanate in host basalts and secondary precipitates. The RS data suggest that the reason for RS cyanate signatures in the carbonate samples could be due to luminescence artifacts while those detected in the host basalts may be due to hydrolysis chemistry. The cyanate signatures detected in the lava tube samples dominated by sulfates do not seem to be luminescence artifacts but may in fact be evidence of an active microbial nitrogen cycle. Our results inform the spectroscopic detection of cyanates in planetary analog environments and the challenges in their identification. Further work is needed to understand their potential as biosignatures on other planetary bodies.

Natural Gamma Ray Borehole Logging Technique for Estimating Radiogenic Heat Production in Basaltic Environment, Case study from Kodana region, Southern Syria

Con el propósito de evaluar la producción de calor radiactivo (HP, por sus siglas en inglés) se han utilizado dos técnicas nucleares en un entorno basáltico de Kodana, en el sur de Siria. Estos son: sondeo de pozos para el registro de rayos gamma de origen natural (Ra) y espectrometría de rayos gamma. Las medidas de Ra se convierten a valores HP con base a la relación de Bucker y Rybach. La subestimación de los valores HP en el caso de estudio del sondo de pozos en Kodana señala la necesidad de una modificación de las constantes de la relación de Bucker y Rybach (0.0158 y 0.8). Por ello se propone establecer una nueva ecuación de la siguiente forma: HP (μW/m3) = 0.037 (Ra(API)+ 4.35, más adecuada para caracterizar HP en ambientes basálticos continentales. Además, su eficacia se ha validado con la estimación y análisis del HP en tres pozos adicionales en la región de estudio. El análisis de 377 puntos medidos a lo largo del pozo Kodana muestra que el Ra varía entre 4.93API y 9.31API, con un valor promedio de 6.83API, mientras que el HP corregido y calibrado varía entre 0.32 y 0.51 μW/m3, con un valor promedio de 0.42 μW/m3 . Utilizando multifractales número-concentración y gráficas log-log se distinguen cuatro rangos de valores de HP calibrados en la región de estudio. El primer rango (<0.354μW/m3) está relacionado con basalto denso y masivo; el segundo (0.354–0.41μW/m3) con basalto sólido; el tercero (0.41–0.44μW/m3) con basalto piroclástico, y el cuarto (>0.44μW/m3) con productos de alteración del basalto y arcillas.

Oceanic Core Complex or not? When bathymetric structures challenge seafloor spreading models

We use regional magnetic and local multibeam bathymetric data to investigate the geological nature of a prominent high located off-axis near the junction between the Mohns and the Knipovich ridges, in the Norwegian-Greenland Sea. Given the location of this hill, near the bend marking the junction between these two ultraslow spreading centers and the bathymetric asymmetry on both sides of the ridge, an Oceanic Core Complex, corresponding to the outcropping part of an underlying detachment, was proposed as a possible interpretation. Nevertheless, the magnetization distribution over this hill is compatible with a basaltic environment and magnetic gradients are also identical to those existing in basaltic contexts, pointing towards a similar geology. Finally, a combined plate and magnetic reconstruction reveals that this hill has a conjugate structure and that regional magnetic anomalies are symmetric. These observations rule out the Oceanic Core Complex hypothesis, as detachment surfaces are often associated with a marked spreading asymmetry. We therefore propose that this protruding bathymetric feature should rather be seen as a basaltic hill and the depth asymmetry likely results from seafloor subsidence triggered by the massive accumulation of sediments from the Bear Island Fan, on the eastern flank of the ridge axis.

Geochemical bio-signatures in Martian analogue basaltic environments using laboratory experiments and thermochemical modelling

The identification of geochemical bio-signatures is important for assessing whether life existed on early Mars. In this paper, experimental microbiology and thermochemical modelling were combined to identify potential inorganic bio-signatures for life detection on early Mars. An analogue mixed microbial community from an analogue terrestrial fluvio-lacustrine environment similar to an ancient lacustrine system at Gale Crater was used to study microbial dissolution of a basalt regolith simulant and the formation of bio-signatures over a short time frame (1°month) at 14°C, 2 bar. Microbial growth influenced element dissolution (Mg, Fe, Mn, Ca and K) and the formation of morphologies and Fe-Si amorphous layers on mineral surfaces. Thermochemical models were performed at 14°C, 2 bar; the results were compared with experimental data to predict bio-signatures that would occur over geological timescales. The pH was varied to simulate abiotic and biotic experimental conditions. Model results suggest that, at water to rock ratios of 100 to 38, a less complex secondary mineral assemblage forms during biotic dissolution compared to abiotic weathering. Carbonates, quartz, pyrite and hydroxyapatite form under biotic conditions, whereas in the abiotic system magnetite and phyllosilicates would also precipitate. These results could be used to distinguish between abiotic and biotic basalt weathering processes, aiding the interpretation of data from Mars exploration missions.

Basaltic Lava Tube Hosts a Putative Novel Genus in the Family Solirubrobacteraceae.

ABSTRACTWe report the draft genome sequence of a putative new genus and species, Siliceabacter maunaloa, in the family Solirubrobacteraceae. The members of this family of Actinobacteria are generally Gram positive and mesophilic. Found within a Hawaiian lava tube, this microbe illuminates the types of prokaryotes inhabiting secondary minerals in subsurface basaltic environments.

Geological and structural characterizations of a basaltic environment by vertical electrical soundings and multifractal modeling techniques in Deir El-Adas Area, Yarmouk Basin, Syria

Concentration-number (C-N) fractal modeling technique is adapted and newly proposed to interpret vertical electrical sounding (VES) measurements. This proposed technique is practiced herein on a case study taken from Deir El-Adas, Southern Syria, where four VES geoelectrical profiles (Pro-1, Pro-2, Pro-3, and Pro-4) are interpreted. The general targeting concept of this technique is to use the threshold break points determined by the use of C-N log–log plots to indicate the passage from geoelectrical layer to another one. Different apparent resistivity population ranges are accordingly well determined for the treated geoelectrical data. Those apparent resistivity ranges are consequently used to establish 2D and 3D semi quantitative interpretations of the studied geoelectrical profiles for different fixed spacings AB/2. The established geoelectrical sections clarified the subsurface geological structures and contributed in distinguishing and classifying lateral and vertical different type of basaltic features in the study area. The fractal C-N model can be therefore used to calibrate the ID traditional inversion VES interpretation, particularly in basaltic environments, characterized by sharp and rapid resistivity variations. This calibration is one of the advantages of this fractal technique. This technique is therefore recommended to be applied in other similar basaltic environments.

Self organizing map neural networks approach for lithologic interpretation of nuclear and electrical well logs in basaltic environment, Southern Syria

An approach based on self organizing map (SOM) artificial neural networks is proposed herewith oriented towards interpreting nuclear and electrical well logging data. The well logging measurements of Kodana well in Southern Syria have been interpreted by applying the proposed approach. Lithological cross-section model of the basaltic environment has been derived and four different kinds of basalt have been consequently distinguished. The four basalts are hard massive basalt, hard basalt, pyroclastic basalt and the alteration basalt products- clay. The results obtained by SOM artificial neural networks are in a good agreement with the previous published results obtained by other different techniques. The SOM approach is practiced successfully in the case study of the Kodana well logging data, and can be therefore recommended as a suitable and effective approach for handling huge well logging data with higher number of variables required for lithological discrimination purposes.

Cryogenic Minerals in Hawaiian Lava Tubes: A Geochemical and Microbiological Exploration

ABSTRACTThe Mauna Loa volcano, on the Island of Hawaii, has numerous young lava tubes. Among them, two at high altitudes are known to contain ice year-round: Mauna Loa Icecave (MLIC) and the Arsia Cave. These unusual caves harbor cold, humid, dark, and biologically restricted environments. Secondary minerals and ice were sampled from both caves to explore their geochemical and microbiological characteristics. The minerals sampled from the deep parts of the caves, where near freezing temperatures prevail, are all multi-phase and consist mainly of secondary amorphous silica SiO2, cryptocrystalline calcite CaCO3, and gypsum CaSO4·2H2O. Based on carbon and oxygen stable isotope ratios, all sampled calcite is cryogenic. The isotopic composition of falls on the global meteoric line, indicating that little evaporation has occurred. The microbial diversity of a silica and calcite deposit in the MLIC and from ice pond water in the Arsia Cave was explored by analysis of ∼50,000 small subunit ribosomal RNA gene fragments via amplicon sequencing. Analyses reveal that the Hawaiian ice caves harbor unique microbial diversity distinct from other environments, including cave environments, in Hawaii and worldwide. Actinobacteria and Proteobacteria were the most abundant microbial phyla detected, which is largely consistent with studies of other oligotrophic cave environments. The cold, isolated, oligotrophic basaltic lava cave environment in Hawaii provides a unique opportunity to understand microbial biogeography not only on Earth but also on other planets.

Determination of Geochemical Bio-Signatures in Mars-Like Basaltic Environments.

Bio-signatures play a central role in determining whether life existed on early Mars. Using a terrestrial basalt as a compositional analog for the martian surface, we applied a combination of experimental microbiology and thermochemical modeling techniques to identify potential geochemical bio-signatures for life on early Mars. Laboratory experiments were used to determine the short-term effects of biota on the dissolution of terrestrial basalt, and the formation of secondary alteration minerals. The chemoorganoheterotrophic bacterium, Burkholderia sp. strain B_33, was grown in a minimal growth medium with and without terrestrial basalt as the sole nutrient source. No growth was detected in the absence of the basalt. In the presence of basalt, during exponential growth, the pH decreased rapidly from pH 7.0 to 3.6 and then gradually increased to a steady-state of equilibrium of between 6.8 and 7.1. Microbial growth coincided with an increase in key elements in the growth medium (Si, K, Ca, Mg, and Fe). Experimental results were compared with theoretical thermochemical modeling to predict growth of secondary alteration minerals, which can be used as bio-signatures, over a geological timescale. We thermochemically modeled the dissolution of the basalt (in the absence of biota) in very dilute brine at 25°C, 1 bar; the pH was buffered by the mineral dissolution and precipitation reactions. Preliminary results suggested that at the water to rock ratio of 1 × 107, zeolite, hematite, chlorite, kaolinite, and apatite formed abiotically. The biotic weathering processes were modeled by varying the pH conditions within the model to adjust for biologic influence. The results suggested that, for a basaltic system, the microbially-mediated dissolution of basalt would result in “simpler” secondary alteration, consisting of Fe-hydroxide and kaolinite, under conditions where the abiotic system would also form chlorite. The results from this study demonstrate that, by using laboratory-based experiments and thermochemical modeling, it is possible to identify secondary alteration minerals that could potentially be used to distinguish between abiotic and biotic weathering processes on early Mars. This work will contribute to the interpretation of data from past, present, and future life detection missions to Mars.

Porosity and hydraulic conductivity estimation of the basaltic aquifer in Southern Syria by using nuclear and electrical well logging techniques

An alternative approach using nuclear neutron-porosity and electrical resistivity well logging of long (64 inch) and short (16 inch) normal techniques is proposed to estimate the porosity and the hydraulic conductivity (K) of the basaltic aquifers in Southern Syria. This method is applied on the available logs of Kodana well in Southern Syria. It has been found that the obtained K value by applying this technique seems to be reasonable and comparable with the hydraulic conductivity value of 3.09 m/day obtained by the pumping test carried out at Kodana well. The proposed alternative well logging methodology seems as promising and could be practiced in the basaltic environments for the estimation of hydraulic conductivity parameter. However, more detailed researches are still required to make this proposed technique very performed in basaltic environments.

Heterogeneidad de la vegetación en ambientes basálticos del centro de Argentina.

Se decribe la flora y la vegetación de pasiajes basálticos de la Sierra de Los Cóndores, Córdoba, Argentina. La vegetación se estudió según criterios de la escuela de Braun-Blanquet; la matriz de 98 inventarios × 272 spp. fue clasificada a través del método ISOPAM. El análisis discrimina tres comunidades correspondientes respectivamente a las tres geoformas relevadas en estos paisajes: Islas rocosas (inselbergs), la Matriz Natural que rodea a las Islas y la Matriz Agrícola que circunda al complejo de paisajes basálticos. Las tres comunidades difieren en su composición florística: las Islas rocosas son los sitios menos perturbados, más ricos en especies, con mayor diversidad, mayor número de especies endémicas y su fisonomía está dominada por formas arbustivas. En el otro extremo, la Matriz Agrícola es la más pobre en especies, la de menor diversidad y endemicidad, y predominan las hierbas perennes y anuales. Las Islas rocosas y la Matriz Natural registran bajos números de especies exóticas en su composición, mientras cerca del 50% de la flora de la matriz agrícola se compone de especies adventicias. Los resultados de este estudio revelan la importancia de las islas rocosas basálticas para laconservación del patrimonio natural de la provincia de Córdoba.

Fractal theory modeling for interpreting nuclear and electrical well logging data and establishing lithological cross section in basaltic environment (case study from Southern Syria)

Fractal theory modeling technique is newly proposed in this research for interpreting the combination of nuclear well logging, including natural gamma ray, density and neutron-porosity, and the electrical well logging of long and short normal, for establishing the lithological cross section in basaltic environments. The logging data of Kodana well, localized in Southern Syria are used for testing and applying the proposed technique. The established cross section clearly shows the distribution and the identification of four kinds of basalt which are hard massive basalt, hard basalt, pyroclastic basalt and the alteration basalt products, clay. The concentration- Number (C-N) fractal modeling technique is successfully applied on the Kodana well logging data in southern Syria, and can be used efficiently when several wells with much well logging data with a high number of variables are required to be interpreted.

1D sequential inversion of portable multi‐configuration electromagnetic induction data

ABSTRACTWe present an algorithm that performs sequentially one‐dimensional inversion of subsurface magnetic permeability and electrical conductivity by using multi‐configuration electromagnetic induction sensor data. The presented method is based on the conversion of the in‐phase and out‐of‐phase data into effective magnetic permeability and electrical conductivity of the equivalent homogeneous half‐space. In the case of small‐offset systems, such as portable electromagnetic induction sensors, for which in‐phase and out‐of‐phase data are moderately coupled, the effective half‐space magnetic permeability and electrical conductivity can be inverted sequentially within an iterative scheme. We test and evaluate the proposed inversion strategy using synthetic and field examples. First, we apply it to synthetic data for some highly magnetic environments. Then, the method is tested on real field data acquired in a basaltic environment to image a formation of archaeological interest. These examples demonstrate that a joint interpretation of in‐phase and out‐of‐phase data leads to a better characterisation of the subsurface in magnetic environments such as volcanic areas.

Similar Microbial Communities Found on Two Distant Seafloor Basalts.

The oceanic crust forms two thirds of the Earth’s surface and hosts a large phylogenetic and functional diversity of microorganisms. While advances have been made in the sedimentary realm, our understanding of the igneous rock portion as a microbial habitat has remained limited. We present the first comparative metagenomic microbial community analysis from ocean floor basalt environments at the Lō’ihi Seamount, Hawai’i, and the East Pacific Rise (EPR; 9°N). Phylogenetic analysis indicates the presence of a total of 43 bacterial and archaeal mono-phyletic groups, dominated by Alpha- and Gammaproteobacteria, as well as Thaumarchaeota. Functional gene analysis suggests that these Thaumarchaeota play an important role in ammonium oxidation on seafloor basalts. In addition to ammonium oxidation, the seafloor basalt habitat reveals a wide spectrum of other metabolic potentials, including CO2 fixation, denitrification, dissimilatory sulfate reduction, and sulfur oxidation. Basalt communities from Lō’ihi and the EPR show considerable metabolic and phylogenetic overlap down to the genus level despite geographic distance and slightly different seafloor basalt mineralogy.

English

English

Mesophilic Mineral-Weathering Bacteria Inhabit the Critical-Zone of a Perennially Cold Basaltic Environment

The weathering of silicate in the world's critical-zone (rock-soil interface) is a natural mechanism providing a feedback on atmospheric CO2 concentrations through the carbonate-silicate cycle. We examined culturable bacterial communities from a critical-zone in western Iceland to determine the optimum growth temperature and their ability to solubilize phosphate-containing minerals, which are abundant within the critical-zone area examined here. The majority of isolated bacteria were able to solubilize mineral-state phosphate. Almost all bacterial isolates were mesophilic (growth optima of 20–45°C), despite critical-zone temperatures that were continuously below 15°C, although all isolates could grow at temperatures associated with the critical-zone (−2.8–13.1°C). Only three isolates were shown to have thermal optima for growth that were within temperatures experienced at the critical-zone. These findings show that the bacteria that inhabit the western Icelandic critical-zone have temperature growth optima suboptimally adapted to their environment, implying that other adaptations may be more important for their long-term persistance in this environment. Moreover, our study showed that the cold basaltic critical-zone is a region of active phosphate mineral-weathering.

Geochemical exploration for platinum-group element deposits in Miyi County, Sichuan Province, Southwestern China

A large Pt–Pd geochemical province within the Emeishan basalt province has been identified previously and was considered as an exploration target for platinum-group element (PGE) mineralization. To evaluate thoroughly the prospect of economic Pt–Pd mineralization in this region, a series of geochemical surveys was conducted in a selected area, with an exploration strategy involving the progressive reduction of the target area and stepwise increase in the sampling density. A regional Pt and Pd geochemical anomaly was delineated by a stream sediment survey at a sampling density of 1 sample km −2 over an area of mafic intrusive bodies and basalts in Miyi County, Sichuan Province. In a follow-up phase, three local Pt and Pd geochemical anomalies were defined by data from a stream sediment survey with a density of 4 samples km −2 . Finally, PGE mineralization within a gabbroic rock was discovered in the geochemical anomalies delineated by the following more detailed survey, namely a soil survey with a 100 m × 20 m sampling grid. The level of Pt+Pd mineralization was 0.33 μg g −1 . A new concealed mafic–ultramafic intrusive body containing PGE mineralization was predicted.The success of this case has provided an excellent example of how to identify possible PGE target areas in the basalt environment using geochemical surveys at various scales.

GEOCHEMICAL AND MINERALOGICAL CHARACTERIZATION OF NATASH VOLCANICS, SOUTH EASTERN DESERT, EGYPT

The two ring structures of Western Ghurfa and Gaziret Khashm Natash as well as the ring dyke, G.El Ghurfa have extruded through the volcanic flows. The three rings range in composition from volcanicflows, represented by trachybasalt, trachyandesite, normal trachyte and alkaline trachyte and pyroclasticrocks (agglomerates, tuffs, pumice and scoria). The rings are semicircular to circular in outline range from1 km to 0.6 km.The high contents of uranium in the studied rocks are due to the presence of secondary uranium mineralssuch as meta-autunite and kasolite as well as the accessory minerals bearing uranium such as monazite,xenotime, zircon and allanite.The geochemical studies of the volcanic rocks revealed that the rock samples fall in the trachyte,trachyandesite , trachybasalt and basalt fields. These rocks were originated from alkaline magma, anddeveloped in continental basalt environment. The enrichment of the LREEs (182 - 391 ppm) is most due tothe presences of garnet in the source.

Statistical factor analysis technique for characterizing basalt through interpreting nuclear and electrical well logging data (case study from Southern Syria)

Factor analysis technique is proposed in this research for interpreting the combination of nuclear well logging, including natural gamma ray, density and neutron-porosity, and the electrical well logging of long and short normal, in order to characterize the large extended basaltic areas in southern Syria. Kodana well logging data are used for testing and applying the proposed technique. The four resulting score logs enable to establish the lithological score cross-section of the studied well. The established cross-section clearly shows the distribution and the identification of four kinds of basalt which are hard massive basalt, hard basalt, pyroclastic basalt and the alteration basalt products, clay. The factor analysis technique is successfully applied on the Kodana well logging data in southern Syria, and can be used efficiently when several wells and huge well logging data with high number of variables are required to be interpreted.