Green Tuff Research Articles

Solid–liquid separation by sonochemistry: A new approach for the separation of mineral suspensions

The effect of sonochemistry to acidify solutions was applied for the solid–liquid separation of three kinds of mineral suspensions. At first, the relationship was measured between zeta-potential and pH in these suspensions to find pH levels correspondent to the isoelectric points. Then sonication (200 kHz or 28 kHz) was applied to adjust pH to the isoelectric points and separated particles from solutions by still-standing and spontaneous precipitation. Compared to the conventional methods using filters and chemical agents, the advantage of this sonochemical separation is two-fold. First, it does not require the maintenance of filters. Second, separated particles are easy to use since they are not mixed with pH adjusters and chemical flocculants. Isoelectric zone (ion strength 0.01, concentration 0.001 wt.%) of green tuff, andesite and titanium dioxide suspensions tested in this study were pH 1.1–3.7, 0.8–3.4, 2.7–5.7, respectively. The sonication of green tuff and andesite suspensions at 200 kHz changed the pH to the isoelectric zone despite the pH buffering effect of eluted alkali earth metals, and successfully precipitated the particles. On the contrary, the sonication of these suspensions at 28 kHz failed to adjust pH to the isoelectric zone, and the particles did not precipitate. In addition, the degradation of particles was observed in the SEM photographs of particles sonicated at 28 kHz, whereas no significant change was detected in particles sonicated at 200 kHz. Thus, it is concluded that the optimal frequency is about 200 kHz because its strong chemical effect can easily adjust the pH while its relatively weak physical effect prevents the degradation of particles.

Felsic tuff from Rutland Island — A pyroclastic flow deposit in Miocene-sediments of Andaman-Java subduction complex

The bedded felsic tuff exposed in Rutland Island, Andaman, consists of two facies: white massive tuff with ill-defined bedding contacts (facies-A) and dominantly green tuff exhibiting well-developed turbidite sequence with up-section change from a massive unit to plane laminated units to ripple drift lamination (facies-B). The felsic tuff is vitric to crysto-vitric in nature and contains broken crystals of quartz, feldspar, biotite and glass shards of different shapes and sizes. The bulk chemistry indicates trachyte to dacite compositional range, and high values of Zr relative to Nb and Y suggest convergent margin tectonic setting of the tuff. Dominance of cuspate shards rather than blocky shards in both the facies indicates subaerial eruption of the pyroclasts. Recurrence of turbidites as well as good sorting of crystals and glass suggest that subaerially erupted ash was transported in subaqueous condition. The bed pattern supports rapid deposition of facies-A from high concentration turbidity flow whereas facies-B could be produced by decrease in grain size and suspended-load fallout rate of turbidity current. Regional correlation suggests that felsic volcanism in Sumatra was the source for such early Miocene to middle Miocene tuff.

2P-35 Improvement in efficiency of iron leaching from green tuff using sonication and oxalic acid(Poster Session)

2P-35 Improvement in efficiency of iron leaching from green tuff using sonication and oxalic acid(Poster Session)

A Study on Alteration of Miocene Green Tuffs in the Kuroko-Type Mineralization Area in Odate Basin, Akita Prefecture

A Study on Alteration of Miocene Green Tuffs in the Kuroko-Type Mineralization Area in Odate Basin, Akita Prefecture

Hydrothermal solidification of green tuff / tobermorite composites

Mesoporous green tuff / tobermorite composites were synthesized by hydrothermal treatment of powder compacts consisting of waste green tuff and slaked lime. XRD results showed that chlorite, the mineral responsible for the green coloration of green tuff, remained after hydrothermal treatment. Tobermorite formed as a result of a reaction between the quartz inherent in green tuff and slaked lime. The formation of tobermorite led to an increase in bending strength, reaching 12 MPa after 10 h of hydrothermal treatment, as well as to an increase in specific surface area and mesopore volume. The composite adsorbed a greater quantity of water vapour and ammonia gas than waste green tuff.

Research on the New Method to Precipitate Hinai Green Tuff Suspension using Ultrasound Irradiation

Hinai green tuff is quarried in Odate-shi, Akita prefecture in Japan and used for architectural materials. Hinai green tuff suspension is generated from the cutting and the grinding process and it is necessary to treat the solution with precipitants. A chemical flocculant has been used as a precipitation agent for fine particles in the suspension. However, using a chemical flocculant agent produces a wasteful mixture of particles and flocculants, which are impossible to be used as a resource. Therefore, it is necessary to develop a new precipitation method without using precipitants for green tuff particles. In this study, the zeta potential of Hinai green tuff particles in suspension was measured to gain the basic electrochemical properties of the colloidal suspension. We then developed a new precipitation method using sonochemical reaction at 200 kHz, 200 W. From results of the zeta potential measurement using an electrophoresis method, the particles exhibited −50 mV at pH 7.0 and 0 mV at below pH 4.0. Sonochemical reaction was applied to control the pH of the suspension to precipitate the Hinai green tuff particulate. When ultrasonic irradiation was applied to the Hinai green tuff suspension, the pH decreased to 4.0 in 80 min and finally reached 3.3 in 180 min. We successfully extracted pure Hinai green tuff particles as precipitates from the suspension using ultrasonic irradiation.

A13 超音波を利用した比内緑色凝灰岩懸濁液の沈殿処理に関する研究(口頭発表)

A13 超音波を利用した比内緑色凝灰岩懸濁液の沈殿処理に関する研究(口頭発表)

The addition of geotechnical properties to a geological classification of coarse-grained alluvium in apediment zone

The city of Tehran is founded on Quaternary alluvium, which has been geologically classified by Rieben. The city is located at the foot of the Alborz Mountain Range, which is basically composed of Eocene pyroclastic deposits (green tuff) and other volcanic rocks. The geology and the morphology of the Tehran region is similar to that for other cities located at the foot of mountains. Rieben divided the Tehran alluvia into four categories, identified as A, B, C and D (from oldest to youngest). In the Rieben geological classification system, which is widely used in Iran, the age and general geological characteristics of alluvia are considered, rather than engineering properties. The Rieben and other geological classification systems are described in this paper and geological factors that affect the geotechnical characterization of the Tehran alluvium are discussed. Because of the nature of the Tehran soils, undisturbed samples for laboratory testing are difficult to obtain and the execution of large-scale in situ tests is difficult, expensive and not practical for the majority of construction sites. Accordingly, a geological–geotechnical classification system is required to assess the engineering properties of coarse-grained soils for use in small to medium-sized construction projects. To determine the geotechnical properties of the Tehran alluvia, a number of in situ tests have been undertaken. The test results have been compared with published research results and the Rieben classification system has been extended to cover geotechnical properties. A similar framework could be used to create local geotechnical–geological classification systems of other coarse alluvia in other locations.

The Sorption of Thorium and Americium onto Fresh and Degraded Ordinary Portland Cement and onto Green Tuff

ABSTRACTThe sorption of thorium and americium has been measured onto crushed samples of freshordinary Portland cement (OPC), degraded OPC (DOPC) and green tuff under a range of aqueous conditions as part of research into the disposal of TRU waste in Japan. Sorption onto OPC was measured from deionised water,3 mol dm−3sodium nitrate solution and simulated seawater, and onto DOPC from demineralised water; all solutions were pre-equilibrated with the relevant cement. Sorption onto tuff was measured from pre-equilibrated deionised water, 3 mol dm−3sodium nitrate solution, simulated seawater, OPC leachate and 1 mol dm−3ammonium hydroxide solution. RDvalues were determined from the amount of thorium or americium remaining in solution after centrifugation, 0.45 μm filtration and 10,000 nominal molecular weight cut-off (NMWCO) filtration. Centrifugation gave lower RDvalues than filtration. MeanRDvalues for sorption onto OPC and DOPC were in the range 4 × 104to ≥1 × 106cm3g−1for thorium, and 3 ×103to ≥1 × 105cm3g−1for americium, after filtration through 10,000 NMWCO filters. Mean RDvalues for thorium sorption onto tuff increased from2 × 103cm3g−1in tuff-equilibrated deionised water, to ≥ 4 × 106cm3g−1from ammonium hydroxide solution (10,000 NMWCO-filtration). A similar trend was seen for10,000 NMWCO-iltered americium samples where mean RDvalues increased from 4 × 103cm3g−1in deionised water to 1 × 105cm3g−1in ammonium hydroxide solution.

比内緑色凝灰岩のｐＨ調整作用と微生物活性化効果に関する検討

The green tuff from Hinai town, Akita is popular for architectural materials because of its beautiful pale green color and thermal and moisture retaining properties. When this stone is quarried and grinded for making products, approximately 60% of all quarried stone becomes the waste stone and it is required to be utilized effectively. Hinai-Green tuff is a porous media and it has abilities to neutralize acids and elute some minerals. These abilities may be effective for growth of microbes and our research group carries out the development of effective utilizations of Hinai-Green tuff as microbial activator. In this paper, the effects of Hinai-Green tuff on pH adjustment and microbial activities are described.Hinai-Green tuff had an ability to neutralize both acid and alkaline water and especially neutralized acids effectivelly. For example, acid water of initial pH3 was neutralized to pH7 by adding 10(w/v)% Hinai-Green tuff into the acid water. Therefore, Hinai-Green tuff can neutralize acid soil and water and adjust acid environments to adaptable environments for microbes. Moreover, Hinai-Green tuff could buffer decrease in pH. The pH of water containing Hinai-Green tuff did not decrease rapidly with adding drops of 0.1M HCl, and especially the buffer action was strongly observed at pH 7 to 8. Hinai-Green tuff is very helpful to maintain pH appropriate for microbes for long time against decrease in pH caused by acid rain and/or acid metabolites of microbes. And pH adjustment effects of Hinai-Green tuff were caused by the ion exchange between Ca2+ leached from the stone and H+.Consequently, microbes grew actively in a medium containing Hinai-Green tuff because of its pH adjustment effects. However, microbes did not grow in a medium containing natural zeolite from Futatsui town, Akita. The effects of Futatsui-Zeolite on pH adjustment for acid were low compared with Hinai-Green tuff.

Pyroclastic deposits of Mio-Pliocene age in the Arakan Yoma-Andaman-Java subduction complex, Andaman Islands, bay of Bengal, India

A thick sequence of bedded tuff alternated with non-volcanogenic turbidites is present in the Archipelago Group of rocks (Mio-Pliocene age) of the Andaman Islands. The tuff occurs in three different facies: a) Facies A, white massive tuff with ill defined bedding contacts; b) Facies B, dominantly green and white tuff with ill defined turbidite Tabc, Tab Bouma sequence; and c) Facies C, well defined ash turbidites of Tabc, Tab, Tabc, Tacde sequence. Dominance of cuspate shards with no pervasive alteration and absence of blocky shards are features of subaerial eruption for the pyroclastic rocks. Absence of glass welding and plastic deformation together with the presence of good sorting and recurrence of ash turbidites indicate that subaerially-erupted ash landed in water and behaved as a cold subaqueous flow. Field features show change of flow character from subaqueous debris flow (for Facies A) to recurrent high to low concentration turbidity current (for Facies B), and ultimately to low particle concentration turbidity current (for Facies C). All the tuff varieties are vitric to crystovitric in character, and contain broken crystals of quartz, plagioclase, mica, and glass shards of delicate shape (crescent, cuspate, curved) without any welding features. The tuffs do not contain any lithic fragments of volcanic rocks. Petrography as well as XRD studies show that glass alteration is common in Facies A and is least in green tuff of Facies B. Alteration of glass to clinoptilolite and analcime has been linked to burial diagenesis. The similarity of chemical composition of glass shards (mainly dacite) and bulk rocks, however, indicates negligible chemical change during diagenesis. The origin of Andaman tuff in a convergent margin tectonic setting is assumed as the basis of high Zr/Nb and Zr/Y.

U–Pb Geochronology of VMS mineralization in the Iberian Pyrite Belt

A geochronology study using U–Pb isotope dilution TIMS analyses of zircon has been conducted to determine the ages of volcanic-associated massive sulfide (VMS) deposits in the Iberian Pyrite Belt (IPB), the world's most prolific VMS province. Ages have been determined for host rocks to four VMS systems that span the IPB: the giant Rio Tinto and Aljustrel districts in the central region, Lagoa Salgada to the west, and Las Cruces to the east. A sample of chloritized quartz porphyritic dacite/rhyolite in the footwall of the San Dionisio massive sulfide deposit of the Rio Tinto district is 349.76±0.90 Ma. This is taken as the best age estimate of the mineralization in the Rio Tinto district, probably the world's largest volcanogenic massive sulfide system. Two xenocrystic zircons from the same sample yielded 207Pb/206Pb ages of 414 and 416 Ma, which provide a minimum estimate for the age of the inherited component. A biotite tonalite from the Campofrio area, 3.5 km north of the center of the Rio Tinto district, is chemically similar to the felsic host rock protolith at Rio Tinto. The Campofrio sample has an age of 346.26±0.81 Ma, slightly younger and outside of the 2σ error for the Rio Tinto age; therefore, this phase of this intrusion was not a heat source for the hydrothermal system that formed the deposits of the Rio Tinto district. The Campofrio sample also has three zircon analyses with 207Pb/206Pb minimum ages of 534, 536, and 985 Ma, indicating inheritance from Ordovician and Neoproterozoic sources. In the Aljustrel VMS district, a U–Pb zircon age of 352.9±1.9 Ma characterizes the altered Green Tuff host rock of the Algares deposit, which is slightly older than the Rio Tinto age. Two zircons with 207Pb/206Pb ages of 531 and 571 Ma from this sample indicate inheritance from a Cambrian or older source. The age of mineralization at Lagoa Salgada is given by essentially identical ages of 356.21±0.73 and 356.4±0.8 Ma, for footwall and hanging wall samples, respectively. The hanging wall sample has two zircon analyses with 207Pb/206Pb ages of 464 and 466 Ma, indicating inheritance from an Ordovician or older source. The age for an altered dacite tuff sample from the hanging wall of the Las Cruces deposit is 353.97±0.69 Ma. One zircon analysis from the Las Cruces sample has a 207Pb/206Pb age of 1048 Ma, indicating inheritance from a Neoproterozoic source. These U–Pb ages refine the IPB geochronology provided by previous studies, and they suggest that either volcanism progressed toward the center of the IPB, or that volcanism was broadly static and the strata were progressively rifted to the margins during transtensional basin formation. The zircon inheritance provides direct evidence for Proterozoic to Ordovician sources, reflecting either basement rocks beneath the Phyllite–Quartzite Group during VMS formation in late Tournaisian times, or a Proterozoic to Ordovician detrital component in Phyllite–Quartzite Group source rocks. The presence of an older crustal component is consistent with VMS formation during rift development at a continental margin.

An Early Dynastic Quarry for Stone Vessels at Gebel Manzal El-Seyl, Eastern Desert

The quarry that supplied two of the stones used for vessels during the Early Dynastic Period, green tuff and tuffaceous limestone, has been found on Gebel Manzal el-Seyl in Egypt's Eastern Desert. Scattered across this 3 km long ridge are about 200 excavations, and littering the ground around them are hundreds of roughed-out vessel blanks, several of which are inscribed with the sign ∩. The blanks were carried across the desert at least 200 km to the Nile Valley where the final carving and polishing was done.

Geomorphological and Geological Causes of theTertiary Landslde

The “Green Tuff” region is defined as existence of abundant submarine volcanic rocks of Early Miocene and overlying oil-bearing pelitic clastic sediments of Late Miocene-Pliocene age. The region, which covers the western half of the Tohoku District in Northern Japan, is also characterized by predominant distribution of Tertiary landslides recognized by interpretation through aerophotographs.In this entire region, reserches on the relations between geological and geomorphological conditions and the distribution of landslides are very few. In this paper, the features of Tertiary landslides distribution are especially discussed from geological and geomorphological point of view.The areas of high distribution density of the landslides coincide with the areas where rapid upheaval movement occured during the Quaternary age. Geologically, a large number of the landslides occured in the areas dominated mainly by mudstone and tuff, and in the areas where has been intensively folded since Late Pliocene age.It is a remarkable fact that the distribution pattern of the landslides is conformable with the characteristics of the late Cenozoic crustal movements. This suggests that the occurrence of the landslides is based on the tectonic history, specifically on its latest one of the region. Problems on prediction of landslides should be considered from such a point view.

Evaluation of Some Commercial Ethylene Absorbents and Natural Materials for their Efficiency

Some commercial ethylene absorbents and natural materials were evaluated for their ethylene removal efficiency at different moisture conditions. Among the 13 commercial ethylene absorbents, 6 of them had some deficiencies in the ethylene removal rate or efficiency even under dry conditions. Three of the ethylene absorbents such as artificial zeolite lost their efficiency at high humid conditions. Five of the absorbents released the absorbed ethylene when they were moistened with water. Four of the commercial ethylene absorbents, for example, activated carbon with palladium chloride and molecular sieve treated with potassium bromate, were effective at all moisture conditions. No significant ethylene removal effect was found in natural materials such as green tuff (Oyaishi) and rice hulls. Packed broccoli with polyethylene film was stored at 10°C with or without ethylene absorbents, and the chrolophyll, ascorbic acid and surface color were analyzed. The activated carbon with palladium chloride showed the better effect on the retention of freshness than the activated carbon or artificial zeolite. The results obtained by the evaluation of ethylene absorbents and the effect of ethylene absorbents on the retention of freshness of broccoli were well correlated.

新潟県東頚城地域の比抵抗構造の石油地質学的解釈 ＭＴ法と基礎試錐のデータに基づいて

Magnetotelluric (MT) data were obtained along a line which is almost perpendicular to the strike of the geologic structure in the Higashi-Kubiki area, Niigata prefecture, Japan. The resistivity structure analyzed from a two dimensional inversion of the MT data is consistent with the geologic structure estimated from other survey results. We interpreted the resistivity structure in comparison with the MITI Higashi-Kubiki well data such as resistivity, porosity, temperature, vitrinite reflectance and altered-mineral contents. The results are as follows.(1) Resistive layers at or near surface correspond to the Uonuma formations, which were not altered.(2) Very conductive layers of about 1 to 3Ωm at a depth range from 1 to 3km correspond to the Nishiyama and the Shiiya formations. The low resistivity is primarily due to high contents of smectites which were produced by diagenesis. Because the permeability of rocks containing plenty of smectites is generally low, the conductive layers may form cap rocks.(3) Below the conductive layers, resistivity increases with depth. The relatively resistive zone of about 3 to 100Ωm corresponds to the Upper Teradomari, the Lower Teradomari, the Nanatani formations and the Green Tuffs. According to the logging data of some nearby wells, this resistivity range agrees with a vitrinite reflectance range from 0.5 to 1.2%. Therefore the resistive zone is interpreted as source rocks of this area.(4) Very resistive layers of more than 300Ωm at deeper than about 10km are probably pre-Tertiary basement rocks or intrusive rocks, which contain probably no oil and gas.

Application of a fluorescent technique to the study of the weathering process

Processes and rates of weathering in representative tuff obtained from a Green Tuff region were directly examined using a new fluorescent approach. This approach was developed to visualize microscopically the microcracks and micropores that contribute to deterioration. The following observations were made. Progression of tuff weathering is caused by a delicate balance between chemical alteration and physical disintegration. Weathering occurs in many hidden microcracks and micropores not detected under natural light, but which can be clearly visualized under ultraviolet light. Water pathways, such as microcracks and cavities, accelerated the chemical alteration by increasing the effective surface area of rocks in contact with water. As the reaction proceeds, the constituent materials loosen and alteration products become widespread in the matrix. Secondary amorphous to poorly crystallized materials, such as iron hydroxide and aluminosilicate, precipitate on the fracture surfaces, slowing the progress of weathering. At the ultimate stage of weathering in tuff, all cracks and most of the micropores are filled with secondary materials. These observations on a microscopic scale during tuff weathering agree with the assessment of weathering obtained by measuring porosity, P-wave velocity and tensile strength.

Characteristics of Landslide Configurations and Recent Slope Disasters in the Shiretoko Peninsula, East Hokkaido, Japan

In the Shiretoko Peninsula, totally 645 landslide configurations were identified through aerial photographs. The total area of landslide mass was counted at approximately 10, 000 hectares, and corresponds to 10% of the whole area of the Shiretoko Peninsula. The characteristics of landslide configurations in the Shiretoko Peninsula are summarized as follows:1) Small landslide configurations are found concentrically in the area underlain by Miocene strata. They consist mainly of “green tuffs” and shales interbedded with thin layers of tuff. Large and very large landslide configurations are arranged on the margins of Quaternary subaerial lavas overlying landslideprone Miocene strata, and both of them are found on the flanks of Quaternary stratovolcanoes.2) The landslide configurations are identified as debris slump, rock slump, debris slide, rock slide, earthflow, collapse (debris/rock fall) and debris avalanche types. Although debris slump and rock slump types predominate in this area, bedrock geology and caprock structures make difference in frequency of the type and scale of landslide configurations.3) In the Miocene area, most landslide configurations are debris slump type or debris fall type. Moreover, also recognized are large rock slump and rock slide types.4) On the margins of Quaternary subaerial lavas, making up caprock structures, large landslide configurations are rock slump, collapse and debris avalanche types.5) In the flank of Quaternary stratovolcanoes, there are large rock slumps and slides, giant collapses, and debris avalanches, which are so huge as to change remarkably the shape of volcanoes.Recently, partial sliding in old landslide mass and falling from old landslide scars were triggered by heavy rainfall and earthquakes. Therefore, paticular attention should be paid to landslide configurations near houses and roads from the viewpoint of landslide damage prevention.

爆破地震動観測による甲府盆地の地下構造

Seismic refraction and bore hole data are used to study the structure of the Kofu Basin, which is located in the South Fossa Magna. Observing seismic waves at 33 stations which were aligned along N-S and E-W profiling lines in the basin, we obtained clear seismic signals from the shot, which was detonated near the crossing point of the two lines. There is considerable complexity of the structure throughout the basin. The main features of the basin structure are as follows. The basement with a P-wave velocity of about 5.8km/s is a granitic layer and tilted to the southwestwards. The depth of the layer is more than 2km at the shot point and the basement is overlain by thick sediments from the late Pliocene to the Holocene with relatively low velocities of 3.0-2.1km/s. Only in the western part of the basin, the so-called “Green tuff” layer with a velocity of about 5km/s is distributed at the depth of about 1km.

熱水フラックスとグローバル海洋組成

Hydrothermal flux from mid-oceanic ridges and back arc basins influences global seawater chemistry. For instance, Mg problem (Dreyer, 1974) can be solved by taking into account of Mguptake from seawater due to the interaction of seawater with oceanic crust under hydrothermal conditions. SO42-also removes considerably from seawater to oceanic crust. Ca, Si and K transfer from oceanic crust to seawater. This interaction takes place not only at mid-oceanic ridge axis, but also at mid-oceanic ridge flank system. The influence of hydrothermal flux from present-day back arc basins on seawater chemistry is small, compared with that of midoceanic ridges. However, hydrothermal flux from back arc basins in Circum Pacific region during middle Miocene (25-15 Ma)(e. g. Green tuff activity) is large. Especially, hydrothermal fluxes of volatile elements (S, As, Sb, Bi, Cl) from back arc basins are large, compared with the hydrothermal fluxes from mid-oceanic ridges. It is concluded that global seawater chemistry is controlled not only by exogenic processes (e. g. river input, sedimentation) but also by endogenic processes (e. g. hydrothermal activity).