Presence Of Volcanic Glass Research Articles

Identification and Description of a Silicic Volcaniclastic Layer in Gale Crater, Mars, Using Active Neutron Interrogation

AbstractThe Dynamic Albedo of Neutrons instrument aboard the Mars Science Laboratory rover, Curiosity, has been used to map a stratigraphically conformable layer of high‐SiO material in Gale crater. Previous work has shown that this material contains tridymite, a high‐temperature/low‐pressure felsic mineral, interpreted to have a volcanic source rock. We describe several characteristics including orientation, extent, hydration, and geochemistry, consistent with a volcaniclastic material conformably deposited within a lacustrine mudstone succession. Relationships with widely dispersed alteration features and orbital detections of hydrated SiO suggest that this high‐SiO layer extends at least 17 km laterally. Mineralogical abundances previously reported for this high‐SiO material indicated that hydrous species were restricted to the amorphous (non‐crystalline) fraction, which is dominated by SiO . The low mean bulk hydration of this high‐SiO layer (1.85 0.13 wt.% water‐equivalent hydrogen) is consistent with silicic glass in addition to opal‐A and opal‐CT. Persistent volcanic glass and tridymite in addition to opal in an ancient sedimentary unit indicates that the conversion to more ordered forms of crystalline SiO has not proceeded to completion and that this material has had only limited exposure to water since it originally erupted, despite having been transported in a fluviolacustrine system. Our results, including the conformable nature, large areal extent, and presence of volcanic glass, indicate that this high‐SiO material is derived from the product of evolved magma on Mars. This is the first identification of a silicic volcaniclastic layer on another planet and has important implications for magma evolution mechanisms on single‐plate planets.

Physicochemical Modeling and Experimental Study of the Si–Al–Ti–Fe–Mg–Ca–Na–K–O System

The melting and crystallization of the natural system Si–Al–Ti–Fe–Mg–Ca–Na–K–O, which represents andesite-basalt, an effusive medium rock that contains 35–95% glass, were studied by physicochemical modeling and experimentally. The presence of volcanic glass and the non-equilibration of phenocrystal minerals with the major andesite-basalt composition hamper the obtainment of data on the mineral compositions of such rocks and on the behavior of their melts. The methods described, based on chemical analysis data, make it possible to calculate the melt compositions obtainable in various atmospheres, thereby making it possible to select the most rational use of igneous rocks in the production of mineral fiber, stone ceramics, and cast-stone articles.

Mineralogical and Chemical Records of Icelandic Dust Sources Upon Ny-Ålesund (Svalbard Islands)

This work aims to identify the geochemical and mineralogical markers of Icelandic dust and to differentiate it from the dust of local origin deposited at the Ny-Alesund station. We characterized representative sediment samples from Iceland and Svalbard and compared them to a set of aerosol samples collected in Ny-Alesund to check the existence and type of the mineralogical markers. The sediment samples were analyzed by X-ray diffraction (XRD) to detect the mineralogical constrain of the geochemical markers. Both aerosol and sediment samples were examined by scanning electron microscopy coupled with EDS microanalysis (SEM-EDS) and image analysis to detect and to provide a morpho-chemical characterization of the mineralogical markers of dust provenance. Comparison between local and Icelandic sediments reveals the metal oxide particles as the most representative and distinguishing mineralogical/phase markers for Iceland dust sources. In particular, we have considered the magnetite-chromite and the magnetite-ulvospinel associations as marker facies of the tholeiitic magmatic series and the presence of volcanic glass as a further indicator of provenance from Iceland. The morphochemical characteristics of the metal oxide particles in the aerosol samples compared to those of the sediment samples have proved to be a powerful tool to separate Icelandic dust from other sources for dust. In particular, the small size, higher grain boundary complexity and lower Fe/Cr ratios suggest the influence of anthropogenic sources, well in accordance with the results of air mass backward trajectories which reveal a main contribution from industrialized areas in Eurasia. This study shows the reliability of the geochemical characterization of the metal oxide particles for the identification of the source regions of dust. In addition it provides an evidence that Icelandic dust can be transported long range to Svalbard confirming the importance of High Latitude Dust sources.

Role of weathering of pillow basalt, pyroclastic input and geomorphic processes on the genesis of the Monte Cerviero upland soils (Calabria, Italy)

In this paper we present new data on weathering and soil formation processes affecting alkaline pillow basalts on the summit of Mt. Cerviero (Calabria, southern Italy). We investigated two representative soil profiles using an integrated approach, including pedological, petrographic, mineralogical and geochemical investigations. We distinguished the main features inherited from the hydrothermal alteration of the pillow basalts in a submarine environment from the chemical weathering processes under meteoric conditions. Irregular geochemical patterns and chemical index of alteration values across the soil profiles indicate a lithological discontinuity between the bedrock and the upper soil horizons, as a response to soil rejuvenation, in turn controlled by erosive processes and an allochthonous pyroclastic input. The soil profiles display poor horizonation and an incipient to intermediate degree of weathering, in line with the clay mineralogy (chlorite or hydroxy-interlayered vermiculite, illite, kaolinite and varying mixed-layers). The degeneration microtextures of clay and iron-manganese coatings in one soil profile suggest their relict genesis, with an emplacement under warm-humid conditions during the last interglacial. A Late Pleistocene to Holocene age of soil development is supported by the trachytic composition of volcanic micropumices, correlated to explosive eruptions from the Campania Province or the Aeolian Islands, in both soil profiles. Geochemical indices obtained from selective extractions of pedogenetic Al, Fe and Si pools point to poor andic properties with humus-Al-complexes prevailing over short-range order minerals. Nonetheless, the latter are consistent with the presence of volcanic glass, an optically isotropic pedogenic matrix and the Andosol-like field features of the soil profiles, even if they developed in a non-volcanic area. This should lead to a partial reassessment of the volcanic versus non-volcanic origin of certain Andosols worldwide and claims a good field work as a basis for choosing the best-suited laboratory methods to fill the gap between ordinary lab and field results.

Volcanic Aggregates from Azores and Madeira Archipelagos (Portugal): An Overview Regarding the Alkali Silica Reactions

Alkali-silica reaction (ASR) is a type of deterioration that has been causing serious expansion, cracking and durability/operational issues in concrete structures worldwide. The presence of sufficient moisture, high alkali content in the cement paste and reactive forms of silica in the aggregates are the required conditions for this reaction to occur. Reactive aggregates of volcanic nature have been reported in different countries such as Japan, Iceland and Turkey, among others. The presence of silica minerals and SiO2-rich volcanic glass is regarded as the main cause for the reactivity of volcanic rocks. In Portugal, volcanic aggregates are mainly present in Azores and Madeira Archipelagos and, for several years, there was no information regarding the potential alkali-reactivity of these rocks. Since the beginning of this decade some data was obtained by the work of Medeiros (2011) and Ramos (2013) and by the national research projects ReAVA, (Characterization of potential reactivity of the volcanic aggregates from the Azores Archipelago: implications on the durability of concrete structures) and IMPROVE (Improvement of performance of aggregates in the inhibition of alkali-aggregate reactions in concrete), respectively. In order to investigate the potential alkali-reactivity of aggregates from both archipelagos, a total of sixteen aggregates were examined under the optical microscope and, some of them, also under the Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy. A set of geochemical analyses and laboratory expansion tests were also performed on those volcanic aggregates. The main results showed that the presence of volcanic glass is rare in both archipelagos and that the samples of Madeira Archipelago contain clay minerals (mainly from scoria/tuff formations inter-layered with the lava flows), which can play a role in concrete expansion. The results of the laboratory tests showed that one of the samples performed as potentially reactive in the accelerated mortar-bar test (ASTM C 1260) and that the majority of the Azores samples started to show some expansion just after one year of testing in the concrete prism test (CPT) at 38°C.

Petrological and geochemical characteristics of Palaeogene low-rank coal on the Faroe Islands: Restricted effects of alteration by basaltic lava flows

The first combined petrographic and geochemical investigation of coal from the Faroe Islands was performed as a case study to understand thermal effects from basaltic lava flows on immature coal. The samples were divided into two distinct groups: “normal” coal (xylite and detroxylite) and “altered organic matter” (charcoal and organic particles dispersed in samples rich in altered clastic mineral components or enriched via hydrothermal fluids). The “normal” coal consists primarily of huminite-group material dominated by ulminite. The proportions of material from inertinite and liptinite groups vary from sample to sample. The studied macerals are anisotropic with no observed reaction rims or vacuoles. According to the mean ulminite reflectance in combination with ultimate and proximate analyses, the coal reached the lignite and subbituminous stages. The maceral compositions together with coal palynology indicate a predominance of gelified wood-derived tissues and demonstrate that the coal evolved in wet forest swamps under limno-telmatic to telmatic conditions.Alteration effects on immature coals from overlying basalt flows were relatively limited. Due to relatively rapid heat loss from the basaltic lava, as verified by the presence of volcanic glass (tachylyte), its imposed thermal effects resulted only in development of a thin “anthracite-like” crust on samples with no elevated coal rank. Associated hydrothermal fluids induced coal hydrofracturing with subsequent mineral precipitation and decomposition of the ambient feldspar-rich volcaniclastic sediments. Altered organic matter is enriched in SiO2, Al2O3 and FeOtot, as well as in trace elements such as Ni and Cr. In contrast, these samples are depleted in Hg (<10ppb).

Petrography and geochemistry of Basic Dokhan Volcanics from the Eastern Desert of Egypt and their use as aggregates in concrete mixes

The present paper deals with the petrography and geochemistry of the Basic Dokhan Volcanics, Eastern Desert, Egypt. The basalts from Gabal Wassif, Atalla volcanics, and Gabal Esh Mellaha were tested for use as aggregates in concrete mixes. The representative 12 samples were collected from areas. These samples were examined by using a petrographic microscope to evaluate sample texture, degree of alteration, and the presence of volcanic glass in the matrix. The results obtained indicate that basalt can be used successfully for preparing concrete, but some attention should be paid to the choice of suitable types of basalt. A general improvement in concrete mix properties has been found by using basalt aggregates in the mix.

Magnetic and mineralogical characteristics of rocks at the Mezmaiskaya cave Paleolithic site (Northern Caucasus)

The results of magnetic and microprobe studies of the rock sequences in the Mezmaiskaya cave at the unique multilayer Paleolithic site are discussed. The magnetic properties of rocks are analyzed for 17 lay� ers (upwards from layer 4 to layer 1\1) dated from over 73 ka ago to recent times. The rocks of layer 1C (Early Upper Paleolithic, ~38 ka) are found to have the highest magnetic susceptibility (K) (up to 2500 × 10 -6 SI), which is related to the intensive activity of (Homo sapiens). The minimum K corresponds to the rocks of layer 2, which is overlain by layer 1D. The sizes of magnetic grains vary throughout the rock section. The largest grains are found in the middle part of the section in the Middle Paleolithic layers 2B3, 2B2, 2B1, 2A, and 2. The superparamagnetic fraction is identified in all layers. This fact supports the view that the cave was open as early as the formation of layer 4. According to the thermomagnetic data on the saturation magnetization and the temperature curves of magnetic susceptibility, magnetite is the main carrier of the rock magnetiza� tion; some samples contain iron hydroxides. Samples with iron sulfides (pyrite) are abundant. The study of the hysteresis parameters of rocks showed that the question on whether sulfidebearing rocks are suitable for reliable paleomagnetic determinations requires further laboratory research into the origin of magnetite in the rocks. The chemical composition of rocks composing layer 2B3 and layers 1D (~39 ka) and 2B1 (~45 ka), in which the presence of volcanic ash has been previously established according to the presence of volcanic glass, was determined by detailed microprobe analysis. A wide variety of chemical elements (up to 18 items) was recognized in layers 1D and 2B1. The iron, titan, chrome, manganese content, and concentrations of other components vary from grain to grain. The microprobe analysis of samples from layers 1D and 2B1 revealed a set of magnetic particles with compositions characteristic of volcanic rocks, which supports the ash origin of these layers. Layer 2B3 is established not to be volcanic ash. The results on the volcanic glass in the rocks of layers 1D and 2B1 were published by Golovanova and her colleagues in Current Anthropology in October 2010 (Golovanova et al., 2010).

Possible detrital, diagenetic and hydrothermal sources for Holocene sediments of the Andaman backarc basin

Three sediment cores near the spreading axis in the Andaman backarc basin (ABB) were studied for bulk and clay mineralogy, major, trace and rare earth element (REE) geochemistry in bulk and three selective leaches, to identify sediment sources to this region and to decipher probable hydrothermal contribution. REE and other geochemical data suggest a strong influence of the Irrawaddy River as a major continental source to the ABB sediments. Low carbonate content in the sediments is due to dilution by higher detrital input as well as reduced foraminiferal carbonate contribution because of low sea surface salinity. The contribution from local volcanic sources was identified from the presence of volcanic glass in the sand-sized sediment fraction; higher smectite content in the clay fraction and the trace element data. Mn concentrations in the upper 12 cm are well above those found in pelagic carbonate-free sediments. Mn distribution pattern and oxide nature suggest a hydrothermal source. Other discriminants such as Eu anomaly and Y/Ho ratio also suggest the role of hydrothermal activity. In addition, the association of Mo with Pb, Zn and Cu in the HCl-insoluble residue suggests the presence of sulfidic material probably of hydrothermal origin.

The presence of vanadium in groundwater of southeastern extreme the pampean region Argentina: Relationship with other chemical elements

Changes in the quality of groundwater resources are related to the presence and concentration of contaminants, especially trace elements such as arsenic, boron, fluoride and vanadium. Vanadium is a rare element naturally abundant, generally found in combination with other elements. Vanadium pentoxide is known to have aneugenic effects. Thus, a study was carried out to assess the presence of vanadium in the groundwater of the southeastern pampean region of Argentina, which constitutes the main water supply for the local population. Statistical and correlational analyses were applied to identify possible interrelationships between vanadium and another chemical elements. Vanadium was found in all groundwater samples. The minimum and maximum vanadium concentrations found were 0.05 mg/l and 2.47 mg/l, respectively. Vanadium is significantly correlated with other trace elements such as arsenic, fluoride and boron. The interrelationship between vanadium and the presence of volcanic glass in sediments is not significant as expected.

Quantification of Mixed-Layer Illite-Smectite in Glass Matrices by Fourier-Transform Infrared Spectroscopy

The Fourier-transform infrared (FTIR) technique has been used for both qualitative and quantitative determination in mineral species (McMillan et al., 1988; Pandya et al., 1992; Schroeder, 1992; Yanagisawa et al., 1997; Zhang et al., 1997). The method presents a number of important advantages: simple preparation, high sensitivity, and rapid analysis. The quantitative determination of minerals in the presence of glass is an interesting problem in mineralogy because X-ray diffraction (XRD) methods do not provide accurate results, especially for small mineral components. In this paper, we present a method for quantitative analysis of Al-rich smectite, mixed-layer illite-smectite (I-S), or illite in the presence of volcanic glass using FTIR. A series of hydrothermal-alteration reactions were made on volcanic tuff from the Cabo de Gata region, southeast Spain. The glass was crushed, ground, and calcined at 900°C for 2 h. After calcination, the fraction of 10–200 μm in size was selected. XRD and differential thermal and thermogravimetric analysis did not detect any phase other than glass. The glass chemical composition is: 72.89% SiO2, 14.47% Al2O3, 1.25% Fe2O3, 1.44% MgO, 0.86% CaO, 3.34% Na2O, 4.97% K2O. The hydrothermal reactions were made at 80, 120, and 160°C, for 60, 90, 180, and 360 d, in both deionized water and in solutions with K/Na ratios of 0.01, 0.1, 1, 10, and 100. The total ion concentrations were 1.01, 0.33, 0.20, 0.33, and 1.01 M. Five grams of glass were placed in 25 mL of solution for each reaction. The products of reaction were separated from the solutions and washed repeatedly with deionized water by centrifugation. The fraction of <2 μm in size was separated also by centrifugation (further analysis refers to this fraction). The samples were Ca-exchanged with …

97/04369 National coal resource assessment: Pennsylvanian age coal of the Illinois basin: Hatch, J. R. Proc. Annu. Int. Pittsburgh. Coal Conf., 1996, 13, (1), 178–181

The first combined petrographic and geochemical investigation of coal from the Faroe Islands was performed as a case study to understand thermal effects from basaltic lava flows on immature coal. The samples were divided into two distinct groups: “normal” coal (xylite and detroxylite) and “altered organic matter” (charcoal and organic particles dispersed in samples rich in altered clastic mineral components or enriched via hydrothermal fluids). The “normal” coal consists primarily of huminite-group material dominated by ulminite. The proportions of material from inertinite and liptinite groups vary from sample to sample. The studied macerals are anisotropic with no observed reaction rims or vacuoles. According to the mean ulminite reflectance in combination with ultimate and proximate analyses, the coal reached the lignite and subbituminous stages. The maceral compositions together with coal palynology indicate a predominance of gelified wood-derived tissues and demonstrate that the coal evolved in wet forest swamps under limno-telmatic to telmatic conditions.Alteration effects on immature coals from overlying basalt flows were relatively limited. Due to relatively rapid heat loss from the basaltic lava, as verified by the presence of volcanic glass (tachylyte), its imposed thermal effects resulted only in development of a thin “anthracite-like” crust on samples with no elevated coal rank. Associated hydrothermal fluids induced coal hydrofracturing with subsequent mineral precipitation and decomposition of the ambient feldspar-rich volcaniclastic sediments. Altered organic matter is enriched in SiO2, Al2O3 and FeOtot, as well as in trace elements such as Ni and Cr. In contrast, these samples are depleted in Hg (<10 ppb).

Recognition and Implications of Volcanic Glass Detritus in the Fluvial Deposits of the Middle Frio Formation, South Texas

ABSTRACT Detrital volcanic glass has been identified in fluvial deposits of the middle Frio Formation of South Texas. Petrographic analysis of core samples from Seeligson and Stratton fields reveals abundant unabraded to slightly abraded, very fine sand- to silt-sized glass shards. Gamma-ray log response correlates with the presence of volcanic glass. Volcanic glass and API unit counts markedly increase through the medial third of the middle Frio and diminish toward the upper third of the middle Frio. The stratigraphic and aerial distribution of volcanic glass detritus in middle Frio sandstones and mudstones suggests that volcanic ash was deposited rapidly on the Oligocene coastal plain of South Texas. Ash was apparently also deposited in the catchment basin of fluvial systems delivering sand to the Stratton area. Given the regional biostratigraphic constraints of middle Frio fluvial deposits, the interval containing volcanic glass is regarded as representing the 30- to 34-mya eruptive event in the Trans-Pecos region.

The presence of volcanic glass in soils on the West Coast, South Island, New Zealand

Abstract Soil profiles at 7 of 8 sites studied on the West Coast of the South Island, New Zealand, contain small amounts of volcanic glass in their sand fractions. It is assumed the glass originated from 1 of the more widespread late Quaternary eruptions of the Taupo Volcanic Zone. On the basis of other known occurrences in the South Island, the glass is considered to be from the Kawakawa Tephra (20 550 ± 300 years old).