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1
STRIEDER, ADELIR JOSÉ, and ROBERTO HEEMANN. "Structural Constraints on Paraná Basalt Volcanism and their Implications on Agate Geode Mineralization (Salto do Jacuí, RS, Brazil)." Pesquisas em Geociências 33, no. 1 (June 30, 2006): 37. http://dx.doi.org/10.22456/1807-9806.19525.
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The Paraná-Etendeka Continental Flood Basalt province hosts world-class agate and amethyst geode deposits in Rio Grande do Sul (Brazil; Serra Geral Fm.). Salto do Jacuí Mining District (Rio Grande do Sul, Brasil) has different types of agate geode hosted in vesicular basalt. A series of structural features has recently been investigated in the Salto do Jacuí Mining District, and indicates at least two volcanic episodes: i) normal tholeiitic basalt and dacite eruption, and ii) vesicular basalt and dacite intrusions as sills and dikes. These structural features include: basalt and aeolian sandstone xenoliths in vesicular basalts, vesicular basalt apophyses in massive basalts, sandstone and basalt breccias, sandstone dikes cutting across vesicular lavas and connected to mixed sandstone-agate geodes, sandstone assimilation by vesicular lava, and mixed sandstone and agate geodes. These features show that agate geodes were formed by melting of Botucatu sandstone xenoliths. High density contrast between vesicular basalt and Botucatu sandstone melts makes them immiscible during flow. Botucatu sandstone xenoliths melting is favored by degasing of intrusive volatile-rich basalts. The high-silica globs crystallize dynamically in a closed-system environment, giving rise to agate banding and fibrosity.
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Moyen, Jean-François. "Granites and crustal heat budget." Geological Society, London, Special Publications 491, no. 1 (February 6, 2019): 77–100. http://dx.doi.org/10.1144/sp491-2018-148.
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AbstractThe origin of large I-type batholiths remains a disputed topic. One model states that I-type granites form by partial melting of older crustal lithologies (amphibolites or intermediate igneous rocks). In another view, granites are trapped rhyolitic liquids occurring at the end of fractionation trends defining a basalt–andesite–dacite–rhyolite series. This paper explores the thermal implications of both scenarios, using a heat balance model that abstracts the heat production and consumption during crustal melting. Heat is consumed by melting and by losses through the surface (conductive or advective, as a result of eruption). It is supplied as a basal conductive heat flux, as internal heat production or as advective heat carried by an influx of hot basalt into the crust. Using this abstract approach, it is possible to explore the role different parameters play in the balance of granites formed by differentiation of basalts or by crustal melting. Two end-member situations appear equally favourable to generating large volumes of granites: (1) short-lived environments dominated by high basaltic flux, where granites result mostly from basalt differentiation; and (2) long-lived systems with no or minimal basalt flux, with granites resulting chiefly from crustal melting.
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Karyakin, Yu V., G. N. Aleksandrova, and А. М. Никишин. "Early Jurassic Flood Basalt Volcanism on the Franz Josef Land Archipelago: Geological and Palynostratigraphical Data." Стратиграфия 31, no. 1 (January 1, 2023): 27–51. http://dx.doi.org/10.31857/s0869592x23010039.
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Biostratigraphic evidence of the presence of Early Jurassic flood basalts on the Franz Josef Land archipelago is presented. The flood basalts form layered section with two units, which is not discovered for Early Cretaceous basalts. The lower unit is composed by large-columnar basalts (colonnade), and the upper unit by small-columnar (entablature) chaotic-fan basalts. On the Hooker Island, the basalt flow is exposed on the Sedov Plateau, on the Lunacharsky Rock Cape and, possibly, on Al’banov Cape. On the southern slope of the Sedov Plateau, the basalt flow overlaps sands and sandstones, which contain palynoassemblage of the lower Toarcian. In the Lunacharsky Rock Cape outcrop, the underlying basalt sands are of the Pliensbachian to Early Toarcian chronostratigraphic interval. Apart from the Hooker Island, we observed basalts with the “colonnade/entablature” on three other islands: Scott Keltie, May and Leigh-Smith. The most complete section was found in the western part of the Leigh-Smith Island, where basalts are underlain and overlapped by sand units. The underlying sands in contact with basalts have a quenching zone. There is no quenching zone at the contact with the overlapping sands. A palynocomplex from the lower sand unit is early Toarcian in age. The palynocomplex found in the upper sand unit indicates its accumulation in the interval from the lower part of the late Toarcian to the early Aalenian. A palynological study of the underlying and overlying deposits of the basalt flow has shown that the flow is underlain by continental and coastal-marine sediments of the Pliensbachian to the upper part of the early Toarcian age interval. Basalt flow is overlain by the earliest late Toarcian–early Aalenian marine sediments. According to the modern chronostratigraphic scale, the age of the basalt flow can be estimated as approximately 180 million years, which is quite consistent with the earlier obtained 40Ar/39Ar data of 189.1 ± 11.4 million years. These data indicate that the basalt flow was formed during a narrow stratigraphic interval of the uppermost lower–earliest upper Toarcian.
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Fliedner, Moritz M., and Robert S. White. "Seismic structure of basalt flows from surface seismic data, borehole measurements, and synthetic seismogram modeling." GEOPHYSICS 66, no. 6 (November 2001): 1925–36. http://dx.doi.org/10.1190/1.1486760.
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We use the wide‐angle wavefield to constrain estimates of the seismic velocity and thickness of basalt flows overlying sediments. Wide angle means the seismic wavefield recorded at offsets beyond the emergence of the direct wave. This wide‐angle wavefield contains arrivals that are returned from within and below the basalt flows, including the diving wave through the basalts as the first arrival and P‐wave reflections from the base of the basalts and from subbasalt structures. The velocity structure of basalt flows can be determined to first order from traveltime information by ray tracing the basalt turning rays and the wide‐angle base‐basalt reflection. This can be refined by using the amplitude variation with offset (AVO) of the basalt diving wave. Synthetic seismogram models with varying flow thicknesses and velocity gradients demonstrate the sensitivity to the velocity structure of the basalt diving wave and of reflections from the base of the basalt layer and below. The diving‐wave amplitudes of the models containing velocity gradients show a local amplitude minimum followed by a maximum at a greater range if the basalt thickness exceeds one wavelength and beyond that an exponential amplitude decay. The offset at which the maximum occurs can be used to determine the basalt thickness. The velocity gradient within the basalt can be determined from the slope of the exponential amplitude decay. The amplitudes of subbasalt reflections can be used to determine seismic velocities of the overburden and the impedance contrast at the reflector. Combining wide‐angle traveltimes and amplitudes of the basalt diving wave and subbasalt reflections enables us to obtain a more detailed velocity profile than is possible with the NMO velocities of small‐offset reflections. This paper concentrates on the subbasalt problem, but the results are more generally applicable to situations where high‐velocity bodies overlie a low‐velocity target, such as subsalt structures.
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Maresh, Jennifer, Robert S. White, Richard W. Hobbs, and John R. Smallwood. "Seismic attenuation of Atlantic margin basalts: Observations and modeling." GEOPHYSICS 71, no. 6 (November 2006): B211—B221. http://dx.doi.org/10.1190/1.2335875.
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Paleogene basalts are present over much of the northeastern Atlantic European margin. In regions containing significant thicknesses of layered basalt flows, conducting seismic imaging within and beneath the volcanic section has proven difficult, largely because the basalts severely attenuate and scatter seismic energy. We use data from a vertical seismic profile (VSP) from well 164/07-1 that penetrated [Formula: see text] of basalt in the northern Rockall Trough west of Britain to measure the seismic attenuation caused by the in-situ basalts. The effective quality factor [Formula: see text] of the basalt layer is found from the VSP to be 15–35, which is considerably lower (more attenuative) than the intrinsic attenuation measured on basalt samples in the laboratory. We then run synthetic seismogram models to investigate the likely cause of the attenuation. Full waveform 1D modeling of stacked sequences of lava flows based on rock properties from the same well indicates that much of the seismic attenuation observed from the VSP can be accounted for by the scattering effects of multiple thin layers with high impedance contrasts. Phase-screen seismic modeling of the rugose basalt surface at the top-of-basalt sediment interface, with the magnitude and wavelength of the relief constrained by a 3D seismic survey around the well, suggests that surface scattering from this interface plays a much smaller role than internal scattering in attenuating the seismic signal as it passes through the basalt sequence.
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Greenough, John D., and V. S. Papezik. "The petrology of North Mountain basalts from the wildcat oil well Mobil Gulf Chinampas N-37, Bay of Fundy, Canada." Canadian Journal of Earth Sciences 24, no. 6 (June 1, 1987): 1255–60. http://dx.doi.org/10.1139/e87-119.
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Basalts totalling 236 m in thickness were intersected in the wildcat oil well Mobil Gulf Chinampas N-37 in the Bay of Fundy. A 5.5 m section of conventional core retrieved from the middle of the basalt section sampled two fine-grained, phenocryst-poor, amygdaloidal basalt flows. The basalts, though somewhat altered, show concentrations of ferromagnesian elements (e.g., Fe, Mg, Cr, Ni) and immobile elements (e.g., Zr, Nb, Ta, Hf) as well as chondrite-normalized REE patterns typical of high-Ti quartz-normative tholeiites and are identical to more evolved samples of the North Mountain basalts at Digby. These petrographic and geochemical characteristics allow correlation with middle unit flows of the North Mountain basalts. The lower unit of North Mountain basalt may be as thick in the well as in the Digby area (~200 m), but the upper unit is either missing or very thin (< 68 m). A 25 m thick sedimentary section just above the conventional core but within the basalt sequence has not been reported on land and hints at the existence of a basalt unit not present on North Mountain. The conclusion that North Mountain basalts occur in the Chinampas well suggests that the flows underlie most of the Bay of Fundy, originally covered 9400 km2, and had a total volume of 2350 km3.
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K, Rashidova R., Kurbanov Abdirakhim Ahmedovich, Aliyev T, Jiyanov A. B, Turdieva O. J, and Nurmatov J. T. "Heat Processing and Change of Proper Indicators of Basalts." Land Science 2, no. 2 (September 2, 2020): p1. http://dx.doi.org/10.30560/ls.v2n2p1.
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This paper presents the results of the analysis of the quality of basalts, their heat treatment and studies of changes in the chemical composition of basalts, which leads to a change in the external color of partially processed basalt raw materials (hereinafter referred to as semi-finished product). The results of a study of purified basalt from slime, impurities and hydroxides, changes in the chemical composition of basalt rock are presented.
The prospects of heat treatment of a semi-finished product and obtaining multi-colored products from mineral raw materials is shown. It was found that the optimal firing temperature of the semi-finished product, the possible options for changing the external color and the criterion points of the thermal effect at which the basalt semi-finished product changes the external shade.
These statements are of great scientific and practical interest in the fact that during the heat treatment of a semifinished product, basalt easily overheats and gradually acquires a different color, which occurs to a liquids temperature and allows the future to plan to obtain high-quality multi-colored products from basalts, for example, products for design.
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Young, R. W., C. R. Twidale, and J. T. Hutton. "Silcrete and basalt - discussion." Zeitschrift für Geomorphologie 37, no. 1 (April 23, 1993): 113–15. http://dx.doi.org/10.1127/zfg/37/1993/113.
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Abrahamsen, Niels, and Regin Waagstein. "Magnetic logs from the Lopra-1/1A and Vestmanna-1 wells, Faroe Islands." Geological Survey of Denmark and Greenland (GEUS) Bulletin 9 (May 31, 2006): 41–49. http://dx.doi.org/10.34194/geusb.v9.4857.
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Susceptibility measurements from cores (representing basalt, lapilli-tuffs and tuffs) and magnetic logs from the Lopra-1/1A well are presented. The basalts fall into high- and low-susceptibility groups with no overlap. The high-susceptibility basalts (seven cores) have susceptibilities between 4 and 88 ×10–3 SI and consist of basalt with < 1% vesicles from thick massive units. The low-susceptibility basalts are intergranular, intersertal or hypocrystalline and contain no or very little (< 1%) visible magnetite, are generally more altered than the high-susceptibility basalts and have susceptibilities in the range from 0.6 to 1.4 × 10–3 SI (seven cores). The susceptibility of ten volcaniclastites of lapilli-tuff or tuff varies from 0.4 to 3.8 × 10–3 SI. The cores from the Lopra-1/1A well reveal a bimodal distribution of magnetic susceptibility. Low susceptibilities ranging from 0.4 to 4 are characteristic of altered basalts poor in magnetite, lapilli-tuffs and tuffs. Thus single measurements of susceptibility are of little use in discriminating between these three types of rock. Susceptibility logs from the Lopra-1/1A well show that the variation below 3315 m distinguishes clearly between volcaniclastics (hyaloclastites) with low and fairly constant susceptibility and basalt beds of between 5 and 10 m thickness (with high susceptibility). The volcaniclastics comprise some 60–70% of the sequence between 3315 and 3515 m with the maximum continuous sediment layer being 80 m thick. A 1½ m core of solid basalt at 2381 m and sidewall cores of basalt from the Lopra1/1A well have a mean susceptibility of 22.1 ± 3.5 × 10–3 SI (standard deviation (σ) = 23.6, number of samples (N) = 46), while samples of hyaloclastite (lapilli-tuff and tuff) have a mean susceptibility of 0.85 × 10–3 SI (σ = 0.39, N = 17). The mean values of the rock magnetic parameters for 303 basalt plugs from the Vestmanna-1 well are: Qave = 13.3 ± 0.6 (σ = 11), Save = 11.8 ± 0.6 × 10–3 SI (σ = 11) and Jave = 4.64 ± 0.25 A/m (σ = 4.4). The reversely polarised, lowermost (hidden) part of the c. 4½ km thick lower basalt formation correlates with Chron C26r. The upper (exposed) part of the lower basalt formation correlates with Chrons C26n, C25r and C25n and the more than 2.3 km thick middle and upper basalt formations correlate with Chron C24n.3r.
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Streck, Martin J., Vanessa M. Swenton, William McIntosh, Mark L. Ferns, and Matt Heizler. "Columbia River Rhyolites: Age-Distribution Patterns and Their Implications for Arrival, Location, and Dispersion of Continental Flood Basalt Magmas in the Crust." Geosciences 13, no. 2 (January 31, 2023): 46. http://dx.doi.org/10.3390/geosciences13020046.
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Columbia River province magmatism is now known to include abundant and widespread rhyolite centers even though the view that the earliest rhyolites erupted from the McDermitt Caldera and other nearby volcanic fields along the Oregon–Nevada state border has persisted. Our study covers little-studied or unknown rhyolite occurrences in eastern Oregon that show a much wider distribution of older centers. With our new data on distribution of rhyolite centers and ages along with literature data, we consider rhyolites spanning from 17.5 to 14.5 Ma of eastern Oregon, northern Nevada, and western Idaho to be a direct response to flood basalts of the Columbia River Basalt Group (CRBG) and collectively categorize them as Columbia River rhyolites. The age distribution patterns of Columbia River rhyolites have implications for the arrival, location, and dispersion of flood basalt magmas in the crust. We consider the period from 17.5 to 16.4 Ma to be the waxing phase of rhyolite activity and the period from 15.3 to 14.5 Ma to be the waning phase. The largest number of centers was active between 16.3–15.4 Ma. The existence of crustal CRBG magma reservoirs beneath rhyolites seems inevitable, and hence, rhyolites suggest the following. The locations of centers of the waxing phase imply the arrival of CRBG magmas across the distribution area of rhyolites and are thought to correspond to the thermal pulses of arriving Picture Gorge Basalt and Picture-Gorge-Basalt-like magmas of the Imnaha Basalt in the north and to those of Steens Basalt magmas in the south. The earlier main rhyolite activity phase corresponds with Grande Ronde Basalt and evolved Picture Gorge Basalt and Steens Basalt. The later main phase rhyolite activity slightly postdated these basalts but is contemporaneous with icelanditic magmas that evolved from flood basalts. Similarly, centers of the waning phase span the area distribution of earlier phases and are similarly contemporaneous with icelanditic magmas and with other local basalts. These data have a number of implications for long-held notions about flood basalt migration through time and the age-progressive Snake River Plain Yellowstone rhyolite trend. There is no age progression in rhyolite activity from south-to-north, and this places doubt on the postulated south-to-north progression in basalt activity, at least for main-phase CRBG lavas. Furthermore, we suggest that age-progressive rhyolite activity of the Snake River Plain–Yellowstone trend starts at ~12 Ma with activity at the Bruneau Jarbidge center, and early centers along the Oregon–Nevada border, such as McDermitt, belong to the early to main phase rhyolite identified here.
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Kulieva, Dilafruz, and Mavlon Avezov. "Prospects of using basalt fibers in light industry." E3S Web of Conferences 390 (2023): 05016. http://dx.doi.org/10.1051/e3sconf/202339005016.
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The paper considers the use of basalt ore - natural raw materials of volcanic origin - in Uzbekistan, as well as the wide use of basalt fibers in various sectors of the economy and their further prospects. Basalt rocks are raw materials for production of fibers and ultrafine fibers, belong to magmatic rocks and possess high natural chemical and thermal stability. Basalt rocks are single-component raw materials that have been enriched, melted and homogenized by ancient volcanic activity. However, the main energy input for the primary melting of basalts was carried out by nature. Basalt is a natural raw material ready for fiber production. The article describes the technological process from extraction of fibers from basalt rocks to their spinning and weaving, obtaining finished fabrics. Laboratory analyses to determine their resistance to tearing, stretching and compression are conducted. The possibility of sewing work clothes from basalt fabrics is considered.
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Shao, Yumeng, Danping Yan, Liang Qiu, Hongxu Mu, and Yi Zhang. "Late Permian High-Ti and Low-Ti Basalts in the Songpan–Ganzi Terrane: Continental Breakup of the Western Margin of the South China Block." Minerals 12, no. 11 (October 31, 2022): 1391. http://dx.doi.org/10.3390/min12111391.
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Although the Emeishan Large Igneous Province (ELIP) has been thoroughly researched, the role of the ELIP in the tectonics of the Songpan–Ganzi extensional basin in the eastern Tibetan Plateau has long been argued without any corroborated and robust evidence. We have investigated the basalt succession of the Dashibao Formation along Xindianzi and Xuecheng sections in the southeast margin of the Songpan–Ganzi Terrane (SGT). New SIMS zircon U-Pb ages and geochemical features of the Dashibao Formation are reported in this paper. Zircons of basalt sample XDZ02-1 yielded a weighted mean age of 259.1 ± 1.66 Ma, which is in alignment with the period when the main eruption of the ELIP occurred. Zircons from two tuff samples XDZ05-1 and XC05-2, overlying the basalt succession, were dated at 251.8 ± 1.57 Ma and 251.5 ± 0.27 Ma, respectively. These new dating results revealed a ~10 Ma eruption for the Dashibao basalts. The Dashibao basalts are geochemically classified into alkaline basalts (Group 1) and tholeiitic basalts (Group 2), which are a part of the Emeishan basalt. We thus propose that the Dashibao basalts erupted in a continental rift setting, located at the margin of the ELIP. The temporal and spatial coincidence of the Dashibao basalt, ELIP, and continental rifting in the western margin of the South China Block suggest that the continental breakup is a response to the Permian mantle plume that triggered the separation of the SGT in the eastern Tibetan Plateau.
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Lambert, R. StJ, V. E. Chamberlain, and J. G. Holland. "Ferro-andesites in the Grande Ronde Basalt: their composition and significance in studies of the origin of the Columbia River Basalt Group." Canadian Journal of Earth Sciences 32, no. 4 (April 1, 1995): 424–36. http://dx.doi.org/10.1139/e95-036.
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Flows from the Grande Ronde Basalt of the Columbia River Basalt Group include several with the chemical composition of ferro-andesites. These flows have SiO2 > 55%, MgO < 4%, and also have higher Fe/Mg than the average value for Grande Ronde Basalt. They are also distinctly richer in Cs, Rb, K, Ba, La, Ce, Th, and U than the remainder of the Grande Ronde Basalt flows, and possess small negative Eu anomalies. Their Pb isotopic compositions define a mixing line with a negative slope on a 206Pb/204Pb versus 207Pb/204Pb plot. Their Nd isotopic compositions lie between 143Nd/144Nd = 0.51252 and 0.51264, and their Sr isotopic compositions lie between 87Sr/86Sr = 0.7055 and 0.7060. These values define the enriched end of the Columbia River Basalt Group spectrum on a Sr–Nd epsilon diagram (excluding the Saddle Mountains Basalt). These ferro-andesite flows also form a compositional end member of the Columbia River Basalt Group and are sufficiently distinctive to warrant special consideration. We compare them with lavas from other tholeiitic provinces. Petrogenetically, they can be related to the Grande Ronde Basalt low-Mg basalts by plagioclase fractionation, or by clinopyroxene fractionation in partially melted eclogites. However, the situation may not be that simple, as their unique isotopic compositions are closely related to those of parental mantle materials, perhaps thus requiring separate reservoirs and (or) sources. Extending this argument to other parts of the Columbia River Basalt Group suggests that the origin of these basalts may be in a system of comparatively small magma chambers in the uppermost mantle, frequently replenished from a variety of sources.
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Morishita, Tomoaki, Naoto Hirano, Hirochika Sumino, Hiroshi Sato, Tomoyuki Shibata, Masako Yoshikawa, Shoji Arai, Rie Nauchi, and Akihiro Tamura. "Alkali basalt from the Seifu Seamount in the Sea of Japan: post-spreading magmatism in a back-arc setting." Solid Earth 11, no. 1 (January 7, 2020): 23–36. http://dx.doi.org/10.5194/se-11-23-2020.
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Abstract. We present geochemical and 40Ar∕39Ar age data for a peridotite xenolith-bearing basalt dredged from the Seifu Seamount (SSM basalt) in the northeast Tsushima Basin, southwest Sea of Japan. An 40Ar∕39Ar plateau age of 8.33±0.15 Ma (2σ) was obtained for the SSM basalt, indicating that it erupted shortly after the termination of back-arc spreading in the Sea of Japan. The SSM basalt is a high-K to shoshonitic alkali basalt that is characterized by light rare earth element enrichment. The trace element features of the basalt are similar to those of ocean island basalt, although the Yb content is much higher, indicating formation by the low-degree partial melting of spinel peridotite. The Nd, Sr, and Pb isotopic compositions of the SSM basalt differ from those of back-arc basin basalts in the Sea of Japan. The Sr–Nd isotopic composition of the SSM basalt suggests its source was depleted mid-ocean ridge mantle containing an enriched mantle (EM1) component. The SSM basalt was formed in a post-back-arc extension setting by the low-degree partial melting of an upwelling asthenosphere that had previously been associated with the main phase of back-arc magmatism.
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Liu, Jin, Lida Luo, Jiali Xu, Xiaoxu Zhu, Guoying Shi, and Qingwei Wang. "The Impact of the Composition on the Properties of Simulated Lunar Mare Basalt Fibers." Materials 17, no. 9 (April 26, 2024): 2043. http://dx.doi.org/10.3390/ma17092043.
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Lunar mare basalt is recognized as an important in situ resource on the lunar surface. However, the significant compositional variability of lunar mare basalts introduces uncertainties concerning the potential for their use in fabricating fibers and composite materials. This study investigates the impact of different components on the fiber-forming capabilities of mare basalts by simulating the compositions of basalts collected from several well-known lunar missions and then preparing simulated lunar mare basalt fibers. Raman spectroscopy is primarily employed for analysis and characterization, using “peak area normalization” to explore the impact of compositional fluctuations in the simulated lunar mare basalts on the glass network structure. The findings indicate that an increase in the Fe content raises the likelihood of basalt fibers crystallizing. Additionally, Fe3+ is shown to substitute for Si and Al in constructing bridging oxygen bonds in the network structure, albeit reducing the overall polymerization of the network. Meanwhile, Fe2+ acts as a network modifier to enhance the mechanical properties of the fibers.
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Hooper, P. R., B. A. Gillespie, and M. E. Ross. "The Eckler Mountain basalts and associated flows, Columbia River Basalt Group." Canadian Journal of Earth Sciences 32, no. 4 (April 1, 1995): 410–23. http://dx.doi.org/10.1139/e95-035.
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Recent mapping of flows of the Columbia River Basalt Group between Lewiston and Pomeroy, southeast Washington, places the chemically distinctive Shumaker Creek flow as a new member between the Frenchman Springs and Roza members of the Wanapum Basalt. This leaves the Eckler Mountain Formation composed of only the Robinette Mountain and Dodge chemical types, with the Lookingglass flow forming the base of the overlying Wanapum Basalt. One Robinette Mountain flow and five separate flows of Dodge composition are recognized and traced across the Blue Mountains Anticline of southeast Washington and northeast Oregon. The aerial distribution of the flows is used to constrain the onset of deformation in the Blue Mountains area between the Hite and Limekiln faults. A series of open east–west folds formed during late Wanapum and Saddle Mountains time, cut by northeast-trending faults with left-lateral strain. Chemical variations between Eckler Mountain, Grande Ronde, and Wanapum Basalt flows require different source components. But between the Eckler Mountain flows the variation of most chemical parameters is consistent with fractional crystallization in the crust and can be modeled for major and trace elements. An exception is the behaviour of Cr and Zr/Y between the Robinette Mountain and Dodge flows, which suggests variable partial melting or possibly olivine accumulation.
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Kahle, A., B. Winkler, and A. Radulescu. "Small-angle neutron scattering investigation of the effect of a heat-treatment on the microstructure of porous basalt rocks." Mineralogical Magazine 70, no. 6 (December 2006): 689–95. http://dx.doi.org/10.1180/0026461067060355.
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AbstractSmall-angle neutron scattering has been used to study the microstructure of natural porous basalt rocks. The effect of temperature on the rock microstructure has been investigated on ‘as received’ and heat-treated basalts. The magnitudes of α, the power-law scattering exponent were between 3 and 4 for the majority of the rocks, indicating a surface fractal structure between the basalt matrix and the pore space. Heat-treated basalts show higher α values, and therefore a smoother pore surface. Internal surface areas were determined for all basalts depending on the thermal history.
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Bhardwaj, Priyanka, Mainak Mitra, and Pranab Kumar Saha. "Interpreter's Corner." Leading Edge 40, no. 8 (August 2021): 619–25. http://dx.doi.org/10.1190/tle40080619.1.
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Basaltic reservoirs have produced hydrocarbon from Yurihara Field in Japan, Quiko Depression in China, and Padra Field of Cambay Basin and Western Offshore Basin in India. The availability of fractured, altered, and vesicular basalts contributes to reservoir development in this stratigraphic unit. This study is conducted in the Kutch-Saurashtra Basin, located at the western continental margin of the Indian subcontinent wherein, the Deccan basalt, with a thickness range of 200–2500 m, overlies Mesozoic sediments. The Jurassic and Cretaceous sediments constitute the main source rock in the area. Several wells have been drilled through the entire basalt section, and some are hydrocarbon bearing in basalt. The entire basalt section in the study area has been classified into four major units using gamma-ray logs. These units have been further subdivided into individual flows and correlated all over the basin. Analysis shows that the base of an individual basalt flow is massive, and the top is differentially altered. Crossplot analysis of P-impedance and VP/VS ratio carried out on logs delineates a zone of moderately weathered/altered basalt, which is due to spheroidal weathering and calibrated with sidewall cores. These moderately altered zones between two successive flows of basalt are the probable reservoir facies for hydrocarbon accumulation, provided that there is an overlying seal in the form of massive or completely altered basalt. Three-dimensional seismic data in the area show an alternating reflection pattern in the basalt section due to the alternation of massive and weathered basalt. The seismic signature of basalt in the area is similar to that of a sedimentary sequence in any given area. Continuity of the identified individual flows in seismic scale has been propagated over the entire seismic, and subsequent inversion has facilitated the deciphering of the probable hydrocarbon-bearing locales within basalt.
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Kanayama, Kenji. "Basalt Fibers." Seikei-Kakou 33, no. 4 (March 20, 2021): 117–20. http://dx.doi.org/10.4325/seikeikakou.33.117.
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Rakovan, John. "Pillow Basalt." Rocks & Minerals 80, no. 4 (July 2005): 287. http://dx.doi.org/10.3200/rmin.80.4.287-287.
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ELGHAWABI, SAMIR H., RAWIA E. ZEWER, SAMIHA M. IBRAHIM, and SAMIR R. SELIM. "Basalt Pneumoconiosis." Occupational Medicine 35, no. 4 (1985): 131–33. http://dx.doi.org/10.1093/occmed/35.4.131.
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Kurbonov, A., L. Sattorov, B. Kamolov, and O. Rakhimov. "Chemical and mineralogical studies of basalt “Aydarkul”." BIO Web of Conferences 71 (2023): 02040. http://dx.doi.org/10.1051/bioconf/20237102040.
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In the article, the geologic, structural, and mineralogical composition of the “Aydarkul” basalt mine was studied as a result of research, and a complete analysis of the physical and chemical pieces of the basalt rock was given. Based on the results of theoretical and experimental studies, the physical and chemical foundations of pyro- and hydrometallurgical methods of rock processing - basalt raw materials - have been developed. Technological options are proposed that allow obtaining demanded products of various compositions. A schematic diagram of the complex processing of basalt raw materials has been developed, including the processing of waste and by-products, as well as the extraction of accessory materials. The study found that the basalts of the Aydarkul mine can be used in the electric power industry.
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Reidel, Stephen P., and D. Brent Barnett. "Igneous Rock Associations 27. Chalcophile and Platinum Group Elements in the Columbia River Basalt Group: A Model for Flood Basalt Lavas." Geoscience Canada 47, no. 4 (December 18, 2020): 187–214. http://dx.doi.org/10.12789/geocanj.2020.47.166.
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The Columbia River Basalt Group is the youngest and best preserved continental Large Igneous Province on Earth. The 210,000 km3 of basaltic lavas were erupted between 16.6 and 5 Ma in the Pacific Northwest, USA. The peak of the eruptions occurred over a 700,000-year period when nearly 99% of the basalts consisting of the Steens, Imnaha, Picture Gorge, Grande Ronde and Wanapum Basalts were emplaced. In this study we examined the Platinum Group Elements (PGEs) Pt and Pd, and the chalcophile elements Cu and Zn in the Columbia River Basalt Group. The presence of Pt, Pd and Cu in the compositionally primitive Lower Steens, Imnaha and Picture Gorge Basalts suggests that the Columbia River Basalt Group magma was a fertile source for these elements. The PGEs are contained mainly in sulphides in the earliest formations based on their correlation with immiscible sulphides, sulphide minerals and chalcophile elements. Grande Ronde, Wanapum and Saddle Mountains Basalts are depleted in PGEs and chalcophile elements compared to earlier formations. Sulphur was saturated in many flows and much of it probably came from assimilation of cratonic rock from a thinned lithosphere. We propose a model where the presence or absence of PGEs and chalcophile elements results primarily from the interaction between an advancing plume head and the crust/lithosphere that it encountered. The early lavas erupted from a plume that had little interaction with the crust/lithosphere and were fertile. However, as the plume head advanced northward, it assimilated crustal/lithospheric material and PGE and chalcophile elements were depleted from the magma. What little PGE and chalcophile elements remained in the compositionally evolved and depleted Grande Ronde Basalt flows mainly were controlled by substitution in basalt minerals and not available for inclusion in sulphides.
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Zhang, Cheng, Jianping Chen, Yiwen Pan, Shuangshuang Wu, Jian Chen, Xiaoxia Hu, Yue Pang, Xueting Liu, and Ke Wang. "Geomorphology, Mineralogy, and Chronology of Mare Basalts in the Oceanus Procellarum Region." Remote Sensing 16, no. 4 (February 8, 2024): 634. http://dx.doi.org/10.3390/rs16040634.
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Mare basalts on the lunar surface are tangible expressions of the complex thermal evolution and geological processes that have occurred within the lunar interior. These basaltic manifestations are highly important because they provide invaluable insights into lunar geological evolution. Notably, the Oceanus Procellarum region, which is renowned for its extensive and long-lasting basaltic volcanism, is a premier location to investigate late-stage lunar thermal evolution. The primary aim of this research is to elucidate the geomorphological, compositional, and temporal attributes that define the mare basalts within the Oceanus Procellarum region. To achieve this aim, we comprehensively analyzed the geomorphological features present within the region, leveraging Kaguya/SELENE TC images and digital elevation models. Specifically, these geomorphological features encompass impact craters, wrinkle ridges, sinuous rilles, and volcanic domes. Subsequently, we thoroughly examined the mineralogical attributes of basalts in the Oceanus Procellarum region, leveraging Kaguya/SELENE MI data and compositional map products. To more accurately reflect the actual ages of the mare basalts in the Oceanus Procellarum region, we carefully delineated the geological units within the area and employed the latest crater size-frequency distribution (CSFD) technique to precisely determine their ages. This refined approach allowed for a more comprehensive and accurate understanding of the basaltic rocks in the study area. Overall, our comprehensive study included an in-depth analysis of the volcanic activity and evolution of the Oceanus Procellarum region, along with an examination of the correlation between the mineralogical composition and ages of mare basalts. The findings from this exhaustive investigation reveal a definitive age range for basalt units within the Oceanus Procellarum region from approximately 3.69 Ga to 1.17 Ga. Moreover, the latest mare basalts that formed were pinpointed north of the Aristarchus crater. Significantly, the region has experienced at least five distinct volcanic events, occurring approximately 3.40 Ga, 2.92 Ga, 2.39 Ga, 2.07 Ga, and 1.43 Ga, leading to the formation of multiple basalt units characterized by their unique mineral compositions and elemental abundances. Through the application of remote sensing mineralogical analysis, three primary basalt types were identified: low-titanium, very-low-titanium, and intermediate-titanium basalt. Notably, the younger basalt units exhibit an elevated titanium proportion, indicative of progressive olivine enrichment. Consequently, these younger basalt units exhibit more intricate and complex mineral compositions, offering valuable insights into the dynamic geological processes shaping the lunar surface.
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Mills, Andrea, and Hamish Sandeman. "Lithostratigraphy and lithogeochemistry of Ediacaran alkaline basaltic rocks of the Musgravetown Group, Bonavista Peninsula, northeastern Newfoundland, Canada: an extensional volcanogenic basin in the type-Avalon terrane." Atlantic Geology 57 (August 5, 2021): 207–34. http://dx.doi.org/10.4138/atlgeol.2021.010.
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Volcanic rocks of the Ediacaran Musgravetown Group on Bonavista Peninsula, Avalon terrane, Newfoundland, include basal ca. 600 Ma calc-alkaline basalt succeeded by continental tholeiite and alkaline rhyolite of the ca. 592 Ma Plate Cove volcanic belt (Bull Arm Formation), indicating a change from subduction-related to extensionrelated tectonic regimes during that interval. Alkalic basalts on northeastern (Dam Pond area) and southwestern (British Harbour area) Bonavista Peninsula occur below and above, respectively, the ca. 580 Ma glacial Trinity facies. Dam Pond basalt occurs in a structural dome intercalated with and flanked by fine-grained, siliciclastic deposits (Big Head Formation) overlain by Trinity facies. The British Harbour basalt occurs above the Trinity facies, in an upward- coarsening sandstone sequence (Rocky Harbour Formation) overlain by red beds of the Crown Hill Formation (uppermost Musgravetown Group). The Rocky Harbour and Big Head formations are likely stratigraphically interfingered proximal and distal deposits, respectively, derived from erosion of the Bull Arm Formation and older Avalonian assemblages.The Big Head basalts have lower SiO2, Zr, FeOT, P2O5, TiO2 and higher Mg#, Cr, V, Co and Ni contents, and are therefore more primitive than the more FeOT-, TiO2-, and P2O5-rich British Harbour basalts. Large-ionlithophile and rare-earth-element concentrations and ratios indicate that both suites originated from low degree partial melts of deep, weakly garnet-bearing, undepleted asthenospheric peridotite sources, with magma conduits likely focused along regional extensional faults. The protracted and episodic extension-related volcanic activity is consistent with a geodynamic setting that evolved from a mature arc into extensional basins with slowly waning magmatism, possibly involving slab rollback and delamination followed by magmatic underplating. The duration and variation of both volcanism and sedimentation indicate that the Musgravetown Group should be elevated to a Supergroup in order to facilitate future correlation of its constituent parts with other Avalonian basins.
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Nazarov, Sayfulla, Khasan Razzokov, Gayrat Shirinov, Erkin Niyozov, Rano Rashidova, Mirzo Rasulov, and Bakhtiyor Ganiev. "Investigation of thermal properties and composition on basalts of the Aydarkul deposit by methods DTA/DTG and X-ray diffraction." E3S Web of Conferences 389 (2023): 01023. http://dx.doi.org/10.1051/e3sconf/202338901023.
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To study the applicability of the basalt fiber through various experimental works in thermal and chemical environments, lining heat-insulating materials basis on basalt of Aydarkul deposit were compared and discussed. The identification and study phase pert structures lining heat-insulating materials basis on basalt of Aydarkul deposit used X-ray diffraction analysis. The basalt fiber showed better strength retention than the glass fiber at relatively high temperature. The article studies the endothermic effects of the thermolysis process, which appear at a temperature of 80 ÷240 0C. They show the decomposition of clay impurities or the removal of hygroscopic water contained in rocks. The chemical and mineralogical composition of the basalts of the Aydarkul deposit has been studied by such modern methods as X-ray diffraction and differential thermal analysis methods.
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Japsen, Peter, Morten Sparre Andersen, Lars Ole Boldreel, Lars Ole Boldreel, Regin Waagstein, Robert S. White, and Michael Worthington. "Seismic and petrophysical properties of Faroe Islands basalts: the SeiFaBa project." Geological Survey of Denmark and Greenland (GEUS) Bulletin 4 (July 20, 2004): 53–56. http://dx.doi.org/10.34194/geusb.v4.4784.
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Flood basalt-covered basins exist worldwide along continental margins and are now in focus as targets for future hydrocarbon exploration. It is generally difficult to image through the basalt cover by conventional seismic reflection methods, and this is a major challenge to future petroleum exploration offshore the Faroe Islands. Long-offset profiling has proven very successful (White et al. 2003). Surprisingly, however, it is possible to image through kilometre-thick basalt sequences on some conventional profiles. Details of basalt stratigraphy are revealed on old, reprocessed seismic profiles as well as on recently acquired profiles, even though the imaging may be unsuccessful on nearby profiles (e.g. Boldreel & Andersen 1993). This stresses the need for a better understanding of the acoustic and other physical properties of basalt as well as of the degree of three-dimensional heterogeneity. The SeiFaBa project (Seismic and petrophysical properties of Faroes Basalt, 2002–2005) is funded by the Sindri Group as part of the programmes for licensees within the Faroese offshore area, and addresses these issues with special focus on the subaerially extruded flood basalts of the Faroe Islands (cf. Japsen et al. in press).
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Nelson, Faye E., René W. Barendregt, and Mike Villeneuve. "Stratigraphy of the Fort Selkirk Volcanogenic Complex in central Yukon and its paleoclimatic significance: Ar/Ar and paleomagnetic data." Canadian Journal of Earth Sciences 46, no. 5 (May 2009): 381–401. http://dx.doi.org/10.1139/e09-025.
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Brunhes, Matuyama, Kaena, and Mammoth age basaltic lava flows (Tertiary–Quaternary Selkirk Volcanics) were sampled in west-central Yukon. The mean characteristic remanent magnetization (ChRM) direction of the flows sampled in this and previous studies has a declination of 348.7° and an inclination of 70.8° (n = 42, k = 99.6, α95 = 2.2°) (all on lower hemisphere). The time range represented in this study (ca. 3.25 to ca. 0.004 Ma) is great enough to have confidently averaged secular variation. Sediment associated with the basalt has a mean declination of 7.6° and inclination of 78.8° (n = 5, k = 5.6, α95 = 35.7°). A new 40Ar–39Ar date on the reversely magnetized basal basalts at Ne Ch’e Ddhäwa places the eruption in the Mammoth subchron of the Gauss Normal Chron. The newly dated basal basalt at Ne Ch’e Ddhäwa precedes the initial continental glaciation in Yukon and is older than the Fort Selkirk vent (Lower Mushroom), which was previously thought to be the oldest eruption at Fort Selkirk Volcanic Complex (FSVC). This basal flow at Mushroom is dated at 1.82 ± 0.03 Ma and the uppermost flow is reproducibly dated at 1.36 ± 0.04 Ma. Till on the flanks of a subglacial volcanic mound called Ne Ch’e Ddhäwa (informal) is older than previously thought; its reverse magnetization indicates an Early Pleistocene age rather than the Reid glaciation, which falls during the Brunhes Normal Chron. The paleomagnetism of Tertiary–Quaternary Selkirk Volcanics outcrops outside the FSVC was studied for the first time. The ChRM direction of basalt at the northern edge of the northern Cordillera volcanic province agrees with FSVC directions, suggesting that this flow reflects the same period of volcanism. This suggests that an Eocene K–Ar date, previously thought to be unreliable, may well be correct.
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Hussain, M. Faruque, Md Shofiqul Islam, and Mithun Deb. "Petrological and geochemical study of the Sylhet trap basalts, Shillong plateau, N.E. India: Implications for petrogenesis." European Journal of Geosciences 2, no. 1 (February 24, 2020): 01–18. http://dx.doi.org/10.34154/2020-ejgs-0201-1-18/euraass.
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Sylhet Traps exposed along the southern margin of Shillong plateau, Northeast India are subalkaline tholeiitic basalts. The basalts are generally massive but occasionally contain large amygdules of zeolites and chalcedony. Microscopically, some basalts show porphyritic texture with olivine phenocrysts. Phenocryst assemblage of plagioclase ± clinopyroxene ± olivine implies crystallization at shallow level. SEM-EDX analysis shows occurrences of spinel with Ni and Cr within the basalts therefore indicating partial melting of the subcontinental lithospheric mantle as the possible source materials for the basalts. The multi-element plot for the basalts shows two distinct trends: one with significant enrichment of LILE and depletion of HFSE and plot similar to OIB (Type 1) while the other trends are chara cterized by slight enrichment of LILE and negative anomalies at Nb, P and Ti (Type 2). Chondrite-normalized REE patterns for Type 1 basalt shows very high enrichment of LREE and a strong right dip HREE pattern and also plots similar to typical OIB while Type 2 show a slight enrichment of LREE over HREE with small Eu anomaly. The geochemical signatures suggest crustal contamination by plume-derived magma produced by low degree of partial melting for Type 1 basalt. Type 2 basalt was produced by partial melting of subcontinental lithospheric mantle, which may be triggered by plume upwelling.
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Kadyrova, Zulayho, Shokhista Niyazova, Munira Kazakova, and Aman Purkhanatdinov. "Physico-chemical studies of Arvaten basalt for the production of mineral fiber." E3S Web of Conferences 431 (2023): 06027. http://dx.doi.org/10.1051/e3sconf/202343106027.
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The article carried out complex studies to determine the chemical, chemical-mineralogical composition, acidity and viscosity modules of basalt from the Arvaten deposit. It has been established that the basalts of this deposit can be used as a raw material for the production of stone casting materials, in the form of mineral wool, as well as basalt fiber with corrective additives.
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Landing, Ed, Georgia Pe-Piper, William SF Kidd, and Karem Azmy. "Tectonic setting of outer trench slope volcanism: pillow basalt and limestone in the Taconian orogen of eastern New York." Canadian Journal of Earth Sciences 40, no. 12 (December 1, 2003): 1773–87. http://dx.doi.org/10.1139/e03-076.
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The only pillow basalt in synorogenic sedimentary rocks at the exterior margin of the Taconic orogen in eastern North America is at Stark's Knob in eastern New York. Earlier reported as extrusive into allochthonous Ordovician slope and rise facies, this small lens (ca. 125+ m long, 39 m thick) is a fault-bounded block in Upper Ordovician melange under the Taconian frontal thrust. Its N-MORB (normal mid-ocean ridge basalt) basalt geochemistry and spinel composition are characteristic of oceanic ridge settings at a water depth of 2 km or more. Abundant limestone lenses on pillows and lava shelves within pillows yielded a middle Late Ordovician gastropod. The limestones are reconciled with this extrusion depth and with limited early Paleozoic pelagic carbonate production by lime mud transport from the Laurentian platform or abiotic carbonate precipitation with sea-water heating during basalt extrusion. A genetic relationship between the parautochthonous Stark's Knob basalts and the allochthonous Jonestown volcanics in slope and rise facies of the Hamburg klippe, eastern Pennsylvania, is likely. Both are Ordovician MORB basalts that reflect volcanism on the subducting outer trench slope prior to the Taconic arc Laurentia collision. Taconic orogenesis may have led to basalt production on the subducting plate by (1) the setting up of orogen-parallel, predominantly strike-slip motion on the subducting slab with MORB basalt generated at offsets in a setting analogous to the Gulf of California or (2) development of faults in a flexure-induced extensional regime. By either process, mafic volcanism appears to be a rare but tectonically significant process on outer trench slopes as continental margins or oceanic plates enter subduction zones.
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Kahn, Maureen, Annia K. Fayon, and Basil Tikoff. "Constraints on the post-orogenic tectonic history along the Salmon River suture zone from low-temperature thermochronology, western Idaho and eastern Oregon." Rocky Mountain Geology 55, no. 1 (July 1, 2020): 27–54. http://dx.doi.org/10.24872/rmgjournal.55.1.27.
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ABSTRACT The abrupt boundary between accreted terranes and cratonic North America is well exposed along the Salmon River suture zone in western Idaho and eastern Oregon. To constrain the post-suturing deformation of this boundary, we assess the cooling history using zircon and apatite (U–Th)/He thermochronology. Pre-Miocene granitic rocks, along a regional transect, were sampled from accreted terranes of the Blue Mountains Province to cratonic North America (Idaho batholith). Each sample was taken from a known structural position relative to a paleotopographic surface represented by the basal unit of the Miocene Columbia River basalts. An isopach map constructed for the Imnaha Basalt, the basal member of the Columbia River Basalt Group (CRBG), confirms the presence of a Miocene paleocanyon parallel to the northern part of Hells Canyon. The (U–Th)/He zircon dates indicate mostly Cretaceous cooling below 200°C, with the ages getting generally younger from west to east. The (U–Th)/He apatite dates indicate Late Cretaceous–Paleogene cooling, which post-dates tectonism associated with the western Idaho shear zone (WISZ). However, (U–Th)/He apatite dates younger than the Imnaha Basalt, with one date of 3.4 ± 0.6 Ma, occur at the bottom of Hells Canyon. These young (U–Th)/He apatite dates occur along the trend of the Miocene paleocanyon, and cannot be attributed to local exhumation related to faults. We propose that burial of Mesozoic basement rocks by the Columbia River basalts occurred regionally. However, the only samples currently exposed at the Earth’s surface that were thermally reset by this burial were at the bottom of the Miocene paleocanyon. If so, exhumation of these samples must have occurred by river incision in the last 4 million years. Thus, the low-temperature thermochronology data record a combination of Late Cretaceous–Paleogene cooling after deformation along the WISZ that structurally overprinted the suture zone and Neogene cooling associated with rapid river incision.
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Kislov, Evgeniy V., Anna V. Aseeva, Vladislav V. Vanteev, Anton Yurievich Sinyov, and Olga A. Eliseeva. "Naryn-Gol Creek Sapphire Placer Deposit, Buryatia, Russia." Minerals 12, no. 5 (April 20, 2022): 509. http://dx.doi.org/10.3390/min12050509.
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A new gem corundum occurrence has been discovered in the Naryn-Gol Creek placer of the Dzhida volcanic field (Russia). In this placer deposit, sapphire associates with large crystals of garnet, spinel, augite, olivine, enstatite, ilmenite, Ti-magnetite, and alkali feldspar. Such a combination of minerals is typical for the placer deposits associated with alkali basalts widely distributed in Southeastern Asia and Australia. We have also found sapphire crystals in phonotephrites of the nearby Cenozoic alkali-basalt paleovolcano Barun Khobol Pravyi, and in basalt sample and trachybasalt from the valley flood basalts. The chemical composition of sapphire is generally typical for ‘basalt’ corundum: it is rich in Fe, and depleted in Ti and Cr. The δ18O SMOW values of corundum and related megacrysts range from 4.6 to 6.8 ‰, thus corresponding to the isotopic signature of igneous rocks. Etched and corroded surfaces of sapphire and other megacrysts indicate that they are in non-equilibrium with their host alkali basalts. Volatile components, CO2 in particular, played a significant role during sapphire formation as gas inclusions reveal.
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Nicholson, Suzanne W., Klaus J. Schulz, Steven B. Shirey, and John C. Green. "Rift-wide correlation of 1.1 Ga Midcontinent rift system basalts: implications for multiple mantle sources during rift development." Canadian Journal of Earth Sciences 34, no. 4 (April 1, 1997): 504–20. http://dx.doi.org/10.1139/e17-041.
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Magmatism that accompanied the 1.1 Ga Midcontinent rift system (MRS) is attributed to the upwelling and decompression melting of a mantle plume beneath North America. Five distinctive flood-basalt compositions are recognized in the rift-related basalt succession along the south shore of western Lake Superior, based on stratigraphically correlated major element, trace element, and Nd isotopic analyses. These distinctive compositions can be correlated with equivalent basalt types in comparable stratigraphic positions in other MRS localities around western Lake Superior. Four of these compositions are also recognized at Mamainse Point more than 200 km away in eastern Lake Superior. These regionally correlative basalt compositions provide the basis for determining the sequential contribution of various mantle sources to flood-basalt magmatism during rift development, extending a model originally developed for eastern Lake Superior. In this refined model, the earliest basalts were derived from small degrees of partial melting at great depth of an enriched, ocean-island-type plume mantle source (εNd(1100) value of about 0), followed by magmas representing melts from this plume source and interaction with another mantle source, most likely continental lithospheric mantle (εNd(1100) < 0). The relative contribution of this second mantle source diminished with time as larger degree partial melts of the plume became the dominant source for the voluminous younger basalts (εNd(1100) value of about 0). Towards the end of magmatism, mixtures of melts from the plume and a depleted asthenospheric mantle source became dominant (εNd(1100) = 0 to +3).
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Lutter, William J., Rufus D. Catchings, and Craig M. Jarchow. "An image of the Columbia Plateau from inversion of high‐resolution seismic data." GEOPHYSICS 59, no. 8 (August 1994): 1278–89. http://dx.doi.org/10.1190/1.1443685.
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We use a method of traveltime inversion of high‐resolution seismic data to provide the first reliable images of internal details of the Columbia River Basalt Group (CRBG), the subsurface basalt/sediment interface, and the deeper sediment/basement interface. Velocity structure within the basalts, delineated on the order of 1 km horizontally and 0.2 km vertically, is constrained to within ±0.1 km/s for most of the seismic profile. Over 5000 observed traveltimes fit our model with an rms error of 0.018 s. The maximum depth of penetration of the basalt diving waves (truncated by underlying low‐velocity sediments) provides a reliable estimate of the depth to the base of the basalt, which agrees with well‐log measurements to within 0.05 km (165 ft). We use image blurring, calculated from the resolution matrix, to estimate the aspect ratio of imaged velocity anomaly widths to true widths for velocity features within the basalt. From our calculations of image blurring, we interpret low velocity zones (LVZ) within the basalts at Boylston Mountain and the Whiskey Dick anticline to have widths of 4.5 and 3 km, respectively, within the upper 1.5 km of the model. At greater depth, the widths of these imaged LVZs thin to approximately 2 km or less. We interpret these linear, subparallel, low‐velocity zones imaged adjacent to anticlines of the Yakima Fold Belt to be brecciated fault zones. These fault zones dip to the south at angles between 15 to 45 degrees.
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He, Hua Nan, and Wei Dong. "Study on Damaged Reinforced Concrete Beams Strengthened with Basalt Fiber Polymer Sheets." Advanced Materials Research 446-449 (January 2012): 2941–44. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2941.
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In practical concrete structures, once reinforced concrete beams serve in case of over cracking or are even damaged due to sudden overloading, it is necessary to repair or strengthened the damaged members for purpose of restoring the structural capacities and keeping the structures working well. At present FRP strengthening technique is one of the most accepted methods available in civil engineering. This paper particularly presents a new FRP material，basal fiber, which is applied to strengthen flexural behaviors of reinforced concrete beams suffering from different amplitudes of cracking damage. Herein, total 4 reinforced concrete beams were tested including one reference beam and three beams strengthened with basalt fiber polymer sheets. The three strengthened beams were preloaded to an expected load and then strengthen by basalt fibers under loading. The test parameters are involved in different pre-loads and layers of basalt fiber sheets. During test some flexural behaviors were obtained in terms of variation of strain in concrete, steel bar and basalt fiber sheet, flexural deflection, collapse loads and the failure modes as well as cracking properties of R.C beams strengthened with basalt fiber sheets. The results of test indicated that flexural behaviors of the beams strengthened under loading with basalt fiber polymer could be improved in different degree with varied initial flexural moment and numbers of basalt fiber.
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O’HARA, M. J. "Flood Basalts, Basalt Floods or Topless Bushvelds? Lunar Petrogenesis Revisited." Journal of Petrology 41, no. 11 (November 1, 2000): 1545–651. http://dx.doi.org/10.1093/petrology/41.11.1545.
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Linthout, K. "Provenance of the Roman basalt stone at Kotterbos (Lelystad, the Netherlands): A geoarchaeological study based on petrographic and geochemical analysis, and comparison with a synthesis of basalt stones along the northern Limes." Netherlands Journal of Geosciences - Geologie en Mijnbouw 94, no. 4 (February 4, 2015): 387–97. http://dx.doi.org/10.1017/njg.2014.45.
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AbstractA solitary unprocessed, 26-cm basalt stone recently found at the Roman (69 AD) site at Kotterbos (Lelystad, the Netherlands), situated 40 km north of the Limes, has been examined petrographically and geochemically. The rock is similar to previously investigated Roman basalt stones and blocks from the Limes in the province of Utrecht. All are alkali olivine basalts and basanites, which are also the dominant rock types in the nearby volcanic hinterland in Germany. On the basis of 23 criteria, including all major and minor elements plus a selection of trace elements, the Kotterbos stone correlates with a distinctive subgroup of Limes basalts. This subgroup is characterised by relatively high Mg# and low TiO2 wt% values, as opposed to the other subgroup with lower Mg# and higher TiO2 wt% values. It is argued that the high Mg#–low TiO2 subgroup and the Kotterbos basalt have common geological provenance(s). Five basalt bodies in the hinterland match the criteria of this subgroup, and might be considered as locations of provenance. Of these five, only Rolandsbogen, located next to an ideal anchorage on the west bank of the Rhine, about 12 km upstream from Bonn, can also conform to sensible Roman demands concerning effective logistics and military safety. Consequently, Rolandsbogen is the most likely site of provenance for the high Mg#–low TiO2 subgroup, which includes the Kotterbos basalt. It is argued that the Kotterbos stone is not a rock that somehow got separated from a shipment of building stones to the northern Limes; rather, it is speculated that the stone was picked up as a stray cobble near the basalt body and taken onboard a Roman vessel moored at the Rolandsbogen anchorage.
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Mathews, W. H. "Neogene Chilcotin basalts in south-central British Columbia: geology, ages, and geomorphic history." Canadian Journal of Earth Sciences 26, no. 5 (May 1, 1989): 969–82. http://dx.doi.org/10.1139/e89-078.
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An extensive but generally thin mantle of basalt flows, the Chilcotin Group, covers much of the Interior Plateau of south-central British Columbia. It provides material for dating and for reconstructing the original form of the paleosurface on which it was deposited. K–Ar whole-rock dates demonstrate that several ages of basalt are represented, from Early Miocene (or even Late Oligocene?) to Early Pleistocene, with particularly abundant eruptions about 14–16, 9–6, and 1–3 Ma ago.Basalts of Middle Miocene and later ages, if not the Early Miocene relics as well, clearly rest on land surfaces of low local relief. In places the low-relief surfaces had been incised to depths of 100–200 m and the valleys backfilled with mid-or late Cenozoic sediments prior to burial by the basalts. The low-relief surfaces throughout the area are believed to have been developed close to a common base level, and regional differences in their present elevation are thus largely a product of post-basalt deformation. This is recorded by Miocene or later uplift of the southern Coast Mountains and gentle flexing in parts of the Interior Plateau.Major stream incision to depths of up to 1000 m following uplift provides a convenient, but not infallible, means of distinguishing Chilcotin basalts from mid-Pleistocene and younger "valley basalts."The Chilcotin Group is, for the most part, a small-scale counterpart of the roughly contemporaneous Columbia River basalt group of Washington and Oregon.
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Mirdarsoltany, Mohammadamin, Alireza Rahai, Farzad Hatami, Reza Homayoonmehr, and Farid Abed. "Investigating Tensile Behavior of Sustainable Basalt–Carbon, Basalt–Steel, and Basalt–Steel-Wire Hybrid Composite Bars." Sustainability 13, no. 19 (September 27, 2021): 10735. http://dx.doi.org/10.3390/su131910735.
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One of the main disadvantages of steel bars is rebar corrosion, especially when they are exposed to aggressive environmental conditions such as marine environments. One of the suggested ways to solve this problem is to use composite bars. However, the use of these bars is ambiguous due to some weaknesses, such as low modulus of elasticity and linear behavior in the tensile tests. In this research, the effect of the hybridization process on mechanical behavior, including tensile strength, elastic modulus, and energy absorbed of composite bars, was evaluated. In addition, using basalt fibers because of their appropriate mechanical behavior, such as elastic modulus, tensile strength, durability, and high-temperature resistance, compared to glass fibers, as the main fibers in all types of composite hybrid bars, was investigated. A total of 12 hybrid composite bars were made in four different groups. Basalt and carbon T300 composite fibers, steel bars with a diameter of 6 mm, and steel wires with a diameter of 1.5 mm were used to fabricate hybrid composite bars, and vinyl ester 901 was used as the resin. The results show that, depending on composite fibers used for fabrication of hybrid composite bars, the modulus of elasticity and the tensile strength increased compared to glass-fiber-reinforced-polymer (GFRP) bars by 83% to 120% and 6% to 26%, respectively. Moreover, hybrid composite bars with basalt and steel wires witnessed higher absorbed energy compared to other types of hybrid composite bars.
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Kazakova, M. N., A. A. Eminov, and I. K. Shokоsimov. "CHEMICAL-MINERALOGICAL STUDY OF BASALT AND SERPENTINITE FOR OBTAINING MINERAL FIBER." Steklo i Keramika, no. 16 (April 2023): 40–45. http://dx.doi.org/10.14489/glc.2023.04.pp.040-045.
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The article presents the results of studies on the chemical-mineralogical composition, acidity and viscosity moduli of basalt and serpentinite of the Arvaten deposit. It has been established that the basalts and serpentinites of this deposit can be used as a raw material for the production of stone casting materials, in the form of mineral wool, and with corrective additives are suitable for the production of basalt fiber.
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Ren, Qiubing, Mingchao Li, Shuai Han, Ye Zhang, Qi Zhang, and Jonathan Shi. "Basalt Tectonic Discrimination Using Combined Machine Learning Approach." Minerals 9, no. 6 (June 22, 2019): 376. http://dx.doi.org/10.3390/min9060376.
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Geochemical discrimination of basaltic magmatism from different tectonic settings remains an essential part of recognizing the magma generation process within the Earth’s mantle. Discriminating among mid-ocean ridge basalt (MORB), ocean island basalt (OIB) and island arc basalt (IAB) is that matters to geologists because they are the three most concerned basalts. Being a supplement to conventional discrimination diagrams, we attempt to utilize the machine learning algorithm (MLA) for basalt tectonic discrimination. A combined MLA termed swarm optimized neural fuzzy inference system (SONFIS) was presented based on neural fuzzy inference system and particle swarm optimization. Two geochemical datasets of basalts from GEOROC and PetDB served as to test the classification performance of SONFIS. Several typical discrimination diagrams and well-established MLAs were also used for performance comparisons with SONFIS. Results indicated that the classification accuracy of SONFIS for MORB, OIB and IAB in both datasets could reach over 90%, superior to other methods. It also turns out that MLAs had certain advantages in making full use of geochemical characteristics and dealing with datasets containing missing data. Therefore, MLAs provide new research tools other than discrimination diagrams for geologists, and the MLA-based technique is worth extending to tectonic discrimination of other volcanic rocks.
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Cahoon, Emily B., Martin J. Streck, Anthony A. P. Koppers, and Daniel P. Miggins. "Reshuffling the Columbia River Basalt chronology—Picture Gorge Basalt, the earliest- and longest-erupting formation." Geology 48, no. 4 (January 31, 2020): 348–52. http://dx.doi.org/10.1130/g47122.1.
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Abstract The Columbia River Basalt Group (CRBG) is the world’s youngest continental flood basalt province, presumably sourced from the deep-seated plume that currently resides underneath Yellowstone National Park in the northwestern United States. The earliest-erupted basalts from this province aid in understanding and modeling plume impingement and the subsequent evolution of basaltic volcanism. We explore the Picture Gorge Basalt (PGB) formation of the CRBG, and discuss the location and geochemical significance in a temporal context of early CRBG magmatism. We report new ARGUS-VI multicollector 40Ar/39Ar incremental heating ages from known PGB localities and additional outcrops that we can geochemically classify as PGB. These 40Ar/39Ar ages range between 17.23 ± 0.04 Ma and 16.06 ± 0.14 Ma, indicating that PGB erupted earlier and for longer than other CRBG main-phase units. These ages illustrate that volcanism initiated over a broad area in the center of the province, and the geochemistry of these early lavas reflects a mantle source that is distinct both spatially and temporally. Combining ages with the strongest arc-like (but depleted) geochemical signal of PGB among CRBG units indicates that the shallowest metasomatized backarc-like mantle was tapped first and concurrently, with later units (Steens and Imnaha Basalts) showing increased influence of a plume-like source.
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Francis, P. E., P. Lyle, and J. Preston. "A tholeiitic andesite flow unit among the Causeway Basalts of North Antrim in Northern Ireland." Geological Magazine 123, no. 2 (March 1986): 105–12. http://dx.doi.org/10.1017/s0016756800029769.
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AbstractA tholeiitic andesite flow unit occurs in tholeiitic basalt lava in the Giant's Causeway region of North Antrim, Northern Ireland. It is the first example of an intermediate differentiate to be found among these quartz-normative basalts. Separate magma batches for the preceding and succeeding basalt formations are indicated by their Zr/P2O5 ratios, and by the differing fractionation trends shown by molecular proportion ratio plots. The tholeiitic andesite was probably extruded in a superheated condition with few crystal nuclei, and subsequent undercooling produced an unusual fasciculate/spherulitic texture in contrast to the very fine and even grain of the host basalt. A liquid–liquid interface between the flow units shows small-scale lava mixing.
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Kara, Jaakko, Markku Väisänen, and Hugh O'Brien. "Zircon dating of the basalt and felsic dyke in Haveri, SW Finland." Bulletin of the Geological Society of Finland 94, no. 2 (December 27, 2022): 109–18. http://dx.doi.org/10.17741/bgsf/94.2.001.
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The E-MORB type Haveri basalt differs from the volcanic arc type rocks in the Tampere belt showing no subduction signature. It is considered to have formed in a marginal basin prior to the volcanic arc. We present here zircon U-Pb dating on two samples. The basalt and the felsic dyke yielded 207Pb/206Pb ages of 1902 ± 5 Ma and 1891 ± 2 Ma, respectively, interpreted as crystallisation ages. The basalt also contains older 1.98 Ga grains while the felsic dyke contains older 1.92 Ga, 1.94 Ga, 1.98 Ga and 2.0 Ga grains, which are inferred as inherited. The age dating of E-MORB type basalts can be used to identify the extensional episodes of the accretionary Svecofennian orogeny.
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Hodych, Joseph P., and Richard A. Cox. "Ediacaran U–Pb zircon dates for the Lac Matapédia and Mt. St.-Anselme basalts of the Quebec Appalachians: support for a long-lived mantle plume during the rifting phase of Iapetus opening." Canadian Journal of Earth Sciences 44, no. 4 (April 1, 2007): 565–81. http://dx.doi.org/10.1139/e06-112.
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It has been suggested that the rifting phase of Iapetus Ocean opening in Quebec involved a long-lived mantle plume centered near the Sutton Mountains whose dominant magmatism was first of continental flood basalt composition and later of ocean-island basalt (OIB) composition. We dated the Lac Matapédia and Mt. St.-Anselme basalts, which are thought to have originated from this plume and have dominant OIB-like composition. The U–Pb dating was done on individual zircon crystals using a laser ablation microprobe linked to an inductively coupled plasma – mass spectrometer. Zircons from two basalt flows at Lac Matapédia yielded ages of 565 ± 6 and 556 ± 5 Ma. Zircons from a basalt flow at Mt. St.-Anselme yielded an age of 550 ± 7 Ma. Although the basalts are allochthonous, these should be their ages of extrusion onto Laurentia, as shown by Grenvillian ages yielded by inherited zircons in both Lac Matapédia flows and by zircons in a granitic pebble from the Mt. St.-Anselme Formation. Our dating supports the hypothesis of a long-lived (~615 to ~550 Ma) Sutton Mountains mantle plume involved in Iapetus rifting. It does so by closing a possible gap of ~10 Ma between the end of flood basalt and the beginning of OIB magmatism, and by supporting ~540 (rather than ~570) Ma for the rift-to-drift transition in Quebec. Because plumes move slowly, this hypothesis implies that Laurentia moved slowly from ~615 to ~550 Ma. This is consistent with paleomagnetic evidence, although very rapid true polar wander at ~590 Ma may need to be invoked.
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Larsen, L. M., W. S. Watt, and M. Watt. "Geology and petrology of the Lower Tertiary plateau basalts of the Scoresby Sund region, East Greenland." Bulletin Grønlands Geologiske Undersøgelse 157 (January 1, 1989): 1–164. http://dx.doi.org/10.34194/bullggu.v157.6699.
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The early Tertiary plateau basalts in East Greenland are situated on a continental margin and were erupted during continental break-up and initiation of sea-floor spreading in the North Atlantic. In the region stretching from Scoresby Sund southward to 69°N 40 000 km2of basalts with an average thickness of 1.5 km have been investigated by measuring and flow-to-flow sampling of 130 profiles, followed by major element geochemical analysis and microprobe analysis, trace element analysis and some Sr isotope data. The basalts rest on Mesozoic sediments in the east and on Precambrian gneiss in the west. Six basalt formations are defined: the Magga Dan, Milne Land and Geikie Plateau Formations form a lower regional sequence erupted in one volcanic episode from sites in the NW part of the region; the Rømer Fjord and Skrænterne Formations form an upper regional sequence erupted in a subsequent volcanic episode in which eruption sites moved SE to centres east of the present Atlantic coast; the Igtertivâ Formation and a coast-parallel dyke swarm formed in a third volcanic episode only recorded at the Atlantic coast. The lavas are essentially flat-lying; a narrow strip along the Atlantic coast is extensively block faulted. Single lava flows are extensive (max. 11 000 km2) and voluminous (max. 300 km3). They are well preserved, with metamorphism of the low zeolite facies. All the lavas and most of the dykes are fractionated tholeiitic basalts with Mg/(Mg+Fe2+) ratios of 0.66-0.39 and TiO2 = 1.2-4.5%. The major part (the 'main basalts', 96% by volume) have Mg ratios of 0.56-0.39, while only 4 vol.% are Mg-rich basalts with Mg ratios of 0.66-0.57. A nephelinitic tuff layer occurs at the base of the second sequence. A few dykes are alkaline. The Mg-rich basalts have microphenocrysts of olivine (FO90-70) and chromite, while the main basalts comprise both aphyric and porphyritic sequences. Phenocrysts of plagioclase (An88-37) are abundant, of olivine (FO80-57) are sparse but ubiquitous, and of augite (FS9-20) sparse and often absent. Groundmass phases are olivine (to FO3737), plagioclase (to An13, augite (to FS62), pigeonite (Fs26-50), titanomagnetite and ilmenite. All rocks contain several per cent fine-grained mesostasis. The phenocrysts frequently show disequilibrium textures and a wide range of compositions within one sample. Extrusion temperatures are calculated to 1280-1110°C, and densities to 2.68-2.78 g/cm3, increasing with fractionation. The volcanic episodes are demonstrated in systematic compositional variations with height in the basalt sequence. Each of the two major episodes started with a variety of lava compositions including Mg-rich basalts, followed by a thick sequence of 'main basalts' showing a systematic decrease of TiO2 and other incompatible elements with height, and ending with a reversal to higher TiO2 values. The third episode is not cyclic, and its products have changed incompatible element ratios. The Mg-rich basalts comprise depleted MORB type basalts, relatively enriched olivine tholeiites, and very enriched tholeiites (Mikis type basalt). Sr isotopes show 87Sr/86Sr ratios of 0.7034 in most basalts and 0.7045 in the Mikis type basalt, while some Si-rich basalts have ratios up to 0.7079. The East Greenland basalts are 'initial rifting' basalts very similar to those in Deccan. The magmas have equilibrated at low pressures in crustal magma chambers. The main basalts have fractionated ol + pl + cpx no matter whether they are aphyric or porphyritic. Simple crystal fractionation can account for sub-trends but not for the complete compositional variation of the main basalts. This is considered as resulting from fractionation in open magma chambers which were repeatedly filled, mixed and tapped. The decrease in TiO2 with height in each volcanic episode indicates increasing magma input rate and shorter residence time in the chamber, while the final reversal indicates the decline and cessation of activity. There is evidence for widespread crustal contamination (1-4%) in the magma chambers of the two lowest formations. Crustal contamination of magmas on the way to the surface occurred sporadically throughout both sequences. One case of magma mixing occurred when a Mg-rich basalt magma invaded the regional main basalt magma chamber. The Mg-rich basalts cannot be directly related to each other or to the main basalts. A petrogenetic scheme is suggested where the Mikis type basalt originated in, or contains an addition from, an undepleted or enriched mantle source. All the other magma types originated in a depleted mantle source by varying degrees and possibly depths of melting. Increasing degrees of melting are indicated for the types nephelinite - enriched olivine tholeiite – main basalt parent – MORB type basalt. The MORB type basalt may also be produced by melting of a residuum. The basalts of the third volcanic episode include another component of mantle or basaltic crust. The three recorded volcanic episodes are related to rifting events during the break-up of the North Atlantic continent, viewed as repeated attempts to straighten out a bend in the original line of opening. The two first rifting events failed while the third for a short while produced oceanic crust. Compared to other regions of the North Atlantic volcanic province the Scoresby Sund basalts are similar to basalts from Kangerdlugssuaq, northern East Greenland, West Greenland, the Faeroes, the Vøring Plateau and some basalts on lceland. The main magma source for the North Atlantic province was similar to that of the lceland hotspot, but enriched subcontinental lithosphere may also have participated in the stage of initial rifting. A correlation for the volcanic episodes throughout East Greenland and the Faeroes is proposed.
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Wang, Xiao, Jinggan Shao, Junchao Wang, Minghao Ma, and Bing Zhang. "Influence of Basalt Fiber on Mechanical Properties and Microstructure of Rubber Concrete." Sustainability 14, no. 19 (September 30, 2022): 12517. http://dx.doi.org/10.3390/su141912517.
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The utilization of waste rubber in concrete will reduce pollution and improve the efficiency of resource utilization. The effects of rubber particles and basalt fibers on the compressive strength and splitting tensile strength of concrete were investigated. In addition, the influence of basalt fibers on the mechanical properties and micropore structure of rubber concrete (RC) were analyzed using scanning electron microscopy (SEM) and X-ray computed tomography (CT). The distribution of rubber particles in concrete was also studied. The results indicate that the effects of basalts fibers on the mechanical properties of rubber concrete were significant. The rubber particles were evenly distributed in the concrete. Compared with normal concrete (NC), rubber concrete with 10% rubber particles had lower compressive strength and splitting tensile strength. Compared with rubber concrete, basalt fiber rubber concrete (BFRC) with 2% basalt fibers had no obvious effect on the compressive strength, while significantly improving the splitting tensile strength, refining the pores of rubber concrete, and reducing the porosity of the matrix. The effects of basalt fiber on the properties and pore distribution of RC should be considered in future applications.
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Hoareau, Jean-Luc, Eric Nicolini, Bertrand Fritz, and Eric Delcher. "Geochemical signatures of underground waters in a basaltic tropical environment. Experimental approach." Bulletin de la Société Géologique de France 176, no. 3 (May 1, 2005): 257–67. http://dx.doi.org/10.2113/176.3.257.
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Abstract Introduction The Reunion Island is an oceanic basaltic island (2500 km2) located in the Indian Ocean under tropical climate (fig. 1). It comprises two shield volcanoes (i) the Piton des Neiges (3069 m omsl), active between 2.1 Ma and 12,000 y and now inactive; (ii) the Piton de la Fournaise (2631 m omsl), active still 1 Ma. This volcanic system presents the complete alkaline magmatic series from the most alkaline end-members to the most differentiate ones: oceanite, aphyric basalt, cotectic basalt, zeolitic basalt, plagioclase-rich basalt and mugearite (fig. 2). The humid climate, with a maximum annual rainfall around 12,000 mm on the eastern coast, favours an intense weathering of rocks and probably the formation of impermeable deep levels in the massif [Courteaud et al., 1997], originating a large number of springs in altitude. The chemical composition of these spring waters indicates a variable chemical signature as a function of the lithology of the concerned drainage basins [Join et al., 1997; Hoareau, 2001] : the Mg/Ca ratio in natural waters is respectively 0.3 and 4.3 for plagioclase-rich basalt aquifer and oceanite aquifer (tab. I). This study is therefore devoted to an experimental approach of the origin of these geochemical signatures. Method Experimental weathering was conducted in double, in closed systems (batch) during 200 hours per experiment, at 20oC, using pure water (750 ml). The reacting rock samples had a given parallelepipedic shape (12 mm x 3 mm x 57 mm) and represented the six types of basalts mentioned above for the complete magmatic differentiated series (fig. 2). CO2 gas was bubbled through each reactor in order to simply reproduce (i) natural conditions in soils or (ii) possible deep CO2 contaminations [Nicolini et al., 1991], without studying in detail the effect of a variable CO2 partial pressure. The aqueous samples were collected during each experiment when a significant variation of electrical conductivity was detected. Results The analytical results clearly show that each type of basaltic rock produces in the aqueous reacting fluid a specific geochemical signature (fig. 4b). This signature reflects first the mineralogical composition of the weathered rock and secondly the distribution of the chemical elements in the different mineral phases of the rocks (particularly between crystalline or vitreous phases). The aqueous solutions produced by experimental weathering reach the domain of composition of natural waters, having altered similar rocks, after about thirty five hours when they reach a quasi steady state of concentration for major cations and anions (fig. 3), while the silica concentration still increases (fig. 5). Discussion The intensity of weathering, illustrated first by the electrical conductivity of natural waters (fig. 3), decreases significantly in the following order of reacting basalts: mugearite (112 μS.cm−1), zeolitic basalt (90 μS.cm−1), cotectic basalt (40 μS.cm−1), and the three remaining basalts (30 μS.cm−1). This gives an idea of the total salts (TDS) dissolved by experimental weathering. The potential weathering sequences have been confirmed by a geochemical modelling of the basalt-water interaction [Hoareau, 2001] using a computer code based on thermodynamic options [the KINDIS code, Madé et al., 1994] without using here kinetic laws not enough documented for basaltic rock-forming minerals. These results allowed to suggest what are the possible geological environments for the underground major water circulation pathways, deduced from the characteristics of natural solutions in springs on the volcano. Such an approach can also be used as an indirect prospecting approach of the geology of aquifers in complex geological environments, sometimes very difficult to approach in the field of the Reunion Island, because of their depth. Conclusion The experimental weathering of basaltic rocks representative from the basaltic underground environments in the Reunion Island has shown interesting results: – the hydrolysis seems to be more important in differentiated basalts. As an example, mugearite alteration produced the solutions with the highest total dissolved salts (TDS); – the transfer of sodium and potassium from basalts to solutions is highest when these elements are located in the crystals (fig. 6) more than in the glass fraction. In this way the percentage of sodium in plagioclasic rich basalt (crystal) reaches 16.43% and only 10.86% in the lixiviating solution. In the case of mugearite (glass fraction) the percentages are respectively 42.88% and 5.21%; – the extraction of calcium and magnesium from the basalts is the highest when these elements are located in the vitreous part (mesostase) of the rock, as in mugearite and oceanite (fig. 6). The results underline the fact that the ability of a rock to liberate some elements is strongly related to its petrology. This study also allows to precise more in detail the geochemical signature of the solutions produced by weathering of the basalt as a function of the basalt-forming mineral phases for a given type of basalt : the differentiation of rocks and the proportion of phenocrysts, microlites and glass play obviously an important role in the control of the chemical composition of weathering solutions. Basalt dissolution is clearly incongruent and dependent on the distribution of chemical elements in the different phases of the rock: (glass, mesostase, crystals) as shown by Crovisier et al. [1990] and Legal [1999]. The comparison between computed chemical compositions of weathering solutions (fig. 4b) and compositions of natural spring waters (fig. 4d) is very encouraging and validate the geochemical model for the interpretation of these geochemical signatures, even without using kinetic laws in a first approach. However some discrepancies still exist, probably due to the fact that the reacting rocks in the experiments represent only one type of basalt, while the natural solutions are generally reacting with different types of basalts in complex hydrogeological systems in large drainage basins. The study of these mixing phenomena is now an interesting perspective for future studies. This study may also be completed using geochemical computer codes combining thermodynamic and kinetic approaches of solutions-basalts interactions in coupled mass-transfer models. This is now under development.
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Jati Widiatama, Angga, Happy Christin Natalia, Rinaldi Ikhram, Lauti Dwita Santy, Joko Wahyudiono, Lanang Rangga Setia Wiguna, and Syifa Faranabila. "Various sources of rare earth element enrichment at Manamas volcanic rock, Timor Island." IOP Conference Series: Earth and Environmental Science 882, no. 1 (November 1, 2021): 012044. http://dx.doi.org/10.1088/1755-1315/882/1/012044.
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Abstract Manamas volcanic rock formed due to crustal thinning in fore arc setting. This research aims to provide information and the enrichment process of rare earth elements in Manamas Formation on the Timor Island and their tectonic implication. Manamas volcanic rock exposed in Bihati River, Baun, Timor consists of two different types of basalts, namely alkaline basalt and sub alkaline basalt. Analysis using ICP-MS method shows enrichment in large ion lithophile element and high field strength element. Subalkaline basalt has N-MORB patterns and alkaline basalt have OIB patterns. The Nb element is relatively impoverished that indicates influence of subduction activities. Thorium and uranium elements also show significant enrichment, due to sedimentary rocks contamination or continental crust or directly from the asthenosphere due to magma upwelling. The two distinctive patterns interpreted due to slab tear phenomenon beneath Timor Island during Australia oceanic plate subduction and recycled oceanic crust beneath Banda Arc.