Tuff Samples Research Articles

Rifting evolution of the Malvinas basin, offshore Argentina: New constrains from zircon U–Pb geochronology and seismic characterization

The Malvinas basin, emplaced offshore southern Patagonia, is an asymmetric extensional basin formed by NNW-striking faults. In this contribution we present a review and updated structural framework for the Malvinas basin, together with two new U–Pb zircon ages for the synrift series. By extrapolation from the neighboring Austral basin, the Middle Jurassic Serie Tobífera unit has typically been interpreted as the synrift infill of the Malvinas basin and correlated to the V2 event of the Chon Aike Magmatic Province. A tuff sample recovered from Serie Tobífera in a well in the Malvinas basin, confirmed this correlation and yielded a crystallization age of 169.6 ± 2 Ma (U–Pb in zircon). Furthermore, a volcanic breccia obtained from a deeper section within the synrift, yielded a Late Triassic age (215 Ma, U–Pb in zircon). This is the first Triassic age in the Malvinas basin and allowed correlation of these deposits with the El Tranquilo basin in the Deseado Massif (onshore Patagonia). The synextensional emplacement of the retroarc Chon Aike Magmatic Province is associated with trenchward migration of the coetaneous volcanic arc. To explain the rotational extension observed in the Chon Aike structural fabric at continental plate-scale, we follow the differential rollback model for the Jurassic evolution of southern Patagonia and introduce a vertical slab tear between Patagonia and Antarctica. The slab tear model provides a border condition for the differential rollback and explains the lateral displacement between Eastern and Western Gondwana during the Mozambique Channel opening. Moreover, the asthenospheric window opened by the slab tear would have produced a thermal anomaly that triggered the opening of the Weddell Sea in the Late Jurassic between Eastern and Western Gondwana.

Sorption of Pb(II) from Aqueous Solutions by Acid-Modified Clinoptilolite-Rich Tuffs with Different Si/Al Ratios

The removal of Pb(II) from aqueous solutions by acid-modified clinoptilolite-rich tuff was investigated in this work. Clinoptilolite-rich tuff samples were treated using H2SO4 at different concentrations. Prior to and following acid treatment, the samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). The pH of the point of zero charge (pHPZC) was also determined as part of this characterization. Batch studies were studied to investigate Pb(II) removal as a function of contact time, initial Pb(II) concentration, adsorbent dosage, and solution pH. The results of the XRD and SEM techniques showed that clinoptilolite is the main mineral of the non- and acid-treated natural zeolite samples. However, EDS analysis indicated that the Si/Al ratio increases as the exchangeable ions decrease with increasing acid concentrations. The optimum conditions for Pb(II) removal for samples with 4.37 ≤ Si/Al ≤ 7.9 were found to be as follows: Contact time of 60–360 min, pH: 6–8, and adsorbent dose of 6 mg g−1; whereas for acid-modified clinoptilolite-rich tuffs with 9.01 ≤ Si/Al ≤ 9.52, these conditions were as follows: Contact time of 1440 min, pH: 8–10, and adsorbent dose of 10 mg g−1. The experimental data were analyzed by kinetic and isotherms models. The results showed that the sorption of Pb(II) on samples with Si/Al ratios of 4.37, 5.31, and 7.91 were in agreement with the pseudo-second order and Langmuir isotherm with qm = 48.54, 37.04, and 14.99 mg g−1, respectively, while the kinetic data and isotherm for samples with 9.01 ≤ Si/Al ≤ 9.52 were found to fit the pseudo-first order and Freundlich model.

Late Carboniferous seismic and volcanic record in the northwestern margin of the Junggar Basin: Implication for the tectonic setting of the West Junggar

The northwestern margin of the Junggar Basin is a transition zone between the Zaire-Hala'alate mountains and the Junggar Basin in West Junggar, which developed a large amount of volcanic rocks in the late Carboniferous. An investigation of the tectonic evolution of this area will be helpful for understanding the accretionary process of West Junggar. Here, we selected well-preserved drill core samples of andesite and andesitic tuff for detailed petrogenesis and geochemical studies, while high-quality seismic and resistivity prospecting cross-sections were also used to reveal the tectonic setting. Zircon U-Pb dating results of three andesite and andesitic tuff samples show that these rocks were erupted at ca. 312 Ma. The results of the geochemical and isotopic analyses of seven samples are characterized by relatively high MgO (1.84–5.52 wt%), Cr (26.19–246.61 ppm), Ni (16.53–82.85 ppm) contents, Ba/La (14.19–218.48) ratios, and high positive ɛHf(t) (+4.8 to +14.2) values, but low TiO2 (0.68–1.25 wt%) contents, FeOT/MgO (1.18–2.81), Sr/Y (5.63–27.40), and Th/Yb (0.19–2.18) ratios, which are similar to the Bieluagaxi sanukitoids of West Junggar. LREEs are enriched in all samples, while Nb and Ta are significantly depleted. All the evidence suggests the volcanics were most likely derived from partial melting of oceanic slab that was contaminated by the overlying mantle wedge during the magma ascent. The seismic and resistivity cross-sections show apparent southeastward-vergent imbricate thrust fault systems, implying northwestward subduction in the late Carboniferous. Together with previous studies and our geochemical and geophysical data, we suggest that the formation of these late Carboniferous volcanic rocks is probably related to a northwestward ridge subduction process.

Age, composition and tectonic implications of late Ordovician-early Silurian igneous rocks of the Loel Volcanic Belt, NW Laos

ABSTRACTVolcanic rocks preserved in the Houay kham area, Loei Fold Belt are important components of the giant Paleo-Tethyan igneous belt. These magmatic rocks, previously mapped as Triassic-Jurassic in age, are composed of dacitic tuff, brecciated rhyolite tuff and a small number of dioritic dikes. In this study, LA-ICP-MS zircon U-Pb dating results show that brecciated rhyolite tuff, dacitic tuff, and dioritic dyke samples have ages of 419.8 ± 1.6 Ma, 449.6 ± 2.6 Ma and 417 ± 4.9 Ma. These are the first documented Late Ordovician to Late Silurian volcanic rocks in the Loei Volcanic Belt or in Southeast Asia. Geochemical analyses of these rocks show that all are calc-alkali to high K, formed in a subduction-related, back-arc basin and are intermediate-acid igneous rocks. Dacitic and brecciated rhyolite tuff samples originated from partial melting of mafic crust with medium to strong crustal contamination and weak to medium fractional crystallization. Dioritic dyke samples originated from simultaneous partial melting of gabbroic and metasedimentary rocks with weak to no crustal contamination or fractional crystallization. In the early Ordovician the eastern branch of the Rheic ocean opened and the Indochina terrane drifted away from NE Gondwana and subsequently an Ordovician–Silurian Palaeo-Tethyan Ocean opened.

Constraints on the onset age of the Sturtian glaciation from the Southeast Yangtze Block, South China

ABSTRACTThe Neoproterozoic glaciations represent a milestone in the Earth evolution due to their influence on atmosphere, biosphere and hydrosphere. Evidence for the Sturtian glaciation, the early stage of Cryogenian, has been recorded worldwide, but the precise timing and synchroneity of its counterpart, the Chang’an glaciation, in South China have been controversial. As such, new zircon U–Pb ages from the pre-Sturtian Gongdong Formation and the overlying the Chang’an Formation in southeastern Yangtze Block were reported. The youngest U–Pb zircon age from a tuff sample of the topmost Gongdong Formation was 716.8 ± 6.8 Ma, and that from a sandstone sample of the lower Chang’an Formation was 725.9 ± 4.4 Ma. The zircon weighted mean age of 716.8 ± 6.8 Ma was interpreted as the maximum depositional age of the termination of the Danzhou Group. This age, along with the ages reported from the bottom of the Danzhou Group, constrains deposition of the Danzhou Group to between ca. 820 Ma and ca. 715 Ma. The age of 716.8 ± 6.8 Ma from the top of the Gongdong Formation is consistent with the SIMS U-Pb age of 715.9 ± 2.8 Ma from the Sibao section, as well as ages from the Banxi Group, Liantuo Group, and Kaijianqiao Formation in the Yangtze Block, which further constrain the onset time of the Sturtian glaciation in South China at ca. 715 Ma. It is also, with uncertainties, consistent with ages from pre-Sturtian strata in Laurentia and Oman, which indicates a global synchroneity and extent for the Sturtian glaciation.

Microwave Treatment of Stone Surfaces for the Devitalization of Biodeteriogens

The experimental work described in this paper is aimed at evaluating the possibility of applying microwave heating to a restoration project. The technique involves the application of microwaves to stone surfaces affected by biodeterioration. Results showed that the pests were completely devitalised. The materials chosen for the survey were yellow and grey tuff. Samples of both tuffs were taken in the area of agro nocerino-sarnese and samples of lime mortar and brick were taken from a ruin located in Saint Eustachio (AV). The methodology consists of two phases: in the first, samples of material are placed in a reverberation chamber and treated by varying the parameters of power and exposure time; in the second, they underwent chemical-physical analysis aimed at establishing whether the treatment had induced aesthetic and/or structural alterations. The procedure was performed both on intact samples and on powdered samples for further analysis. Specifically selected and treated samples were subjected to colorimetric analysis, thermogravimetric analysis, of x-ray diffraction, infrared spectroscopy, SEM, and analysis of transport properties and compressive strength. Results from the chemical and structural analyses relating to the samples treated with the protocol showed no differences between the treated and untreated material. The only difference between the two types of material used related to the absorption capacity of water after treatment. From this, it can be deduced that the heating of stone materials using microwaves devitalizes pests, while leaving the substrate unaltered and the microstructure unaffected by any change.

Partitioning and isotopic fractionation of lithium in mineral phases of hot, dry rhyolites: The case of the Mesa Falls Tuff, Yellowstone

Studying the inventory and distribution of lithium (Li) in rhyolitic magmas, and the potential Li isotope fractionation during progressive crystallisation is crucial to understand the formation of economic Li deposits. Lithium concentrations and isotopic compositions of co-existing groundmass glass, quartz, sanidine, plagioclase, clinopyroxene, fayalite, and orthopyroxene from the Mesa Falls Tuff (Yellowstone) were determined using LA-ICP-MS and MC-ICP-MS. The highest Li contents were obtained from quartz-hosted melt inclusions (avg. 244 ppm) and groundmass glass (avg. 43 ppm). Lithium concentrations are lower in mineral phases, decreasing from quartz (avg. 18 ppm), plagioclase (avg. 17 ppm), fayalite (avg. 16 ppm), clinopyroxene (avg. 11 ppm), orthopyroxene (avg. 8 ppm) to sanidine (avg. 6 ppm). Lithium isotopic compositions of bulk tuff samples and major mineral phases reveal a range in δ7Li values (per mil deviation of 7Li/6Li ratio relative to L-SVEC reference material), spanning ~10‰ between the co-existing phases and decreasing from groundmass glass (6.5–7.5‰) to feldspars (plagioclase from −2.3 to −1.4‰; sanidine from −0.6 to −0.1‰). Lithium concentration profiles across sanidine and plagioclase crystals show a decrease towards the crystal rims, which is not observed in the other mineral phases of the Mesa Falls Tuff. The variations identified in feldspar are decoupled from both the major and all other trace element compositions, precluding an origin related to mafic recharge and magma mixing. We propose that they result from Li loss from the melt to a vapour or fluid phase taking place immediately prior to, or synchronously with, eruption. This is supported by the observation that Li contents in quartz-hosted melt inclusions are a factor of six greater than those found in groundmass glass while the concentrations of immobile trace elements are identical. The low-Li rims on sanidine and plagioclase crystals observed in the high-silica Mesa Falls Tuff rhyolite are potential candidates to preserve Li isotopic disequilibrium as has been observed in less evolved systems. The variation in Li abundances within feldspar crystals hints at the potential for kinetic isotopic fractionation to play a role in the reported isotopic compositions of bulk separates. The large elemental database of Li concentrations from the MFT allows us to calculate apparent partition coefficients between groundmass glass and co-existing minerals. These data are compared to fifteen other ignimbrites from the Yellowstone-Snake River Plain province to provide a coherent picture of Li partitioning in hot and dry rhyolites with Li most compatible in quartz and olivine, and least compatible in sanidine.

The organic stratigraphy of Ontong Java Plateau Tuff correlated with the depth-related presence and absence of putative microbial alteration structures.

Structures in geological samples are often interpreted as fossilised life; however, such interpretations are equivocal, as abiotic processes can be invoked to explain their presence. Thus, additional lines of chemical evidence are invaluable in confirming or refuting such morphological evidence. Glass shards in tuff from the Ontong Java Plateau (OJP) contain microtubular structures that are in close proximity to functionalised nitrogen substituted aromatic compounds that may be indicative of the chemical remnants of biological activity. The organic composition of the OJP tuff containing microtubular alteration structures was compared with tuff without such features. In addition, organic matter associated with horizons with compacted remnants of woody material buried in the OJP tuff and overlying pelagic calcareous foraminifer sediment were also characterised, to ascertain the provenance of the organic matter found in the OJP tuff. As a further control, the organic material in submarine and terrestrial basalts from other locations were also characterised providing further evidence to support the view that the organic matter in the OJP tuff is authigenic. Carbon-nitrogen chemistry was detected across all OJP tuff samples irrespective of the presence or absence of microtubular features, but was not detected in either the wood material, the overlying pelagic sediments or in the basalts from other locations. The results indicate no direct link between the OJP nitrogenous organic compounds and the presence or absence of microtubular features.

Detrital geochronology of the Gondwana sequence of the Lesser Himalaya of the Nepal Himalaya

Detrital age relationship between major lithounits of the orogeny and foreland basin strata can elucidate orogenic events. However, analyses of some selected samples of a certain time interval from a sedimentary basin can lead to misjudgement. We present detrital zircon U–Pb age analyses of some older sedimentary strata of the Tansen Group, a renowned basin for the explanation of the Himalayan Orogeny. Sandstone and tuff samples of the Permian and Cretaceous Periods from the Gondwana sequence of the Lesser Himalaya of eastern Nepal and western Nepal were subjected to U–Pb age analyses, and the results were compared with available younger strata of the same basin along with the major lithotectonic units of the Himalaya. The detrital zircon age population of different units enables us to propose a new stratigraphic framework for the eastern Nepal Gondwana sequence and correlate them with the well‐established Gondwana sequence of the western Nepal Lesser Himalaya. This study reveals that the source region for the Gondwana sequence (Permian to Cretaceous) and post‐Gondwana sequence (Eocene to Miocene) is alternating and casts doubt upon the famous implications for the India and Asia collision and metamorphic core exhumation made from the basin analysis of these sedimentary basins of the southern part of the Himalayan Thrust Fold Belt (HTFB). Furthermore, we argue that these basins cannot be used for the reconstruction of collision and exhumation history of the Himalaya as being used. Alternatively, the results are more consistent with the possibilities of recent unconventional hypotheses of sediment contribution of the Greater Himalaya to the Permian strata of the Lesser Himalaya and the Cretaceous rifting of the Tibetan–Himalayan Microcontinent followed by the accretion of the microcontinent before collision of India and Asia.

Removal of Selenium (Se) and Zinc (Zn) inWater by Using Natural Zeolitic Tuff as Adsorbent from Tegalrejo Area, Gedangsari District, Gunungkidul Regency, Special Province Yogyakarta, Indonesia

Heavy metals are one of the most hazardous pollutant in the water. Thereare many methods for heavy metals remediation such as precipitation, oxidation, reverseosmosis, ion exchange and sorption by reactive materials. Zeolite is one of reactive materials have been used for water remediation. Therefero, in this the capability of zeolite from Gedangsari District, Gunung Kidul Regency, Special Province of Yogyakarta, Indonesia, will be invetigated to remidiate contaminated water by selenium (Se) and Zinc (Zn). To answer this objective, several samples of natural zeolitic tuff were taken and charaterized. Laboratory experiment was done by batch test. The results showed that natural zeolitic tuff is an effective adsorbent of Se and Zn and holds great potential material to remove heavy metals in water. The sorption isotherms of Se and Zn confirmed to type of Langmuir or Freundlich isotherms.

Zircon U-Pb geochronology of crystal tuff on Lingshan Island and its geological implications for magmatism, stratigraphic age and geological events

Due to the unique location in the Ludong region, geochronological study of this area is essential for the understanding of the Cretaceous tectonic evolution of Eastern China. Sedimentary sequences interbedded with tuff layers unconformably overlay metamorphic rocks in the Sulu Orogen. This research presents a more reliable geochronological dataset of a tuff layer on Lingshan Island in Qingdao. A total of 103 valid age values from 216 zircon grains were obtained in three fresh tuff samples. Approximately 87% of these zircon ages are dated as the Early Cretaceous, and their peak ages shift from the Aptian stage to the Albian stage. The spatial-temporal relationship between the tuff and the Mesozoic igneous rocks of Eastern China indicate the impact of the Pacific Plate subduction beneath the Asian continent. Six Albian single detrital zircons have a weighted average age of 103.8 ± 1.4 Ma, with the youngest age (103.4 ± 1.4 Ma) constraining the maximum depositional age of the tuff layer. The age sequence of four sections on Lingshan Island is defined in this study: sections A and B belong to the Laiyang Group, and sections C and D are considered the Qingshan Group and were deposited in the Late Cretaceous. Two pre-Cretaceous zircon age peaks were also observed. These age peaks coincide with the magmatic and metamorphic ages preserved in the Sulu Orogen; thus, the Sulu Orogen is the provenance of the sedimentary rocks on Lingshan Island.

The effect of salt crystallization on degradation of volcanic building stones by sodium sulfates and sodium chlorides

Volcanic rocks cropping out in the north-northeast of Afyonkarahisar (Turkey) are extensively used as building stones for the construction of historical buildings with structural and architectonic purposes. Three building stones, including two tuffs and an andesite, were examined in the current research. The scope of this article was to study the decay mechanisms of these porous building stones by salt. For this purpose, laboratory studies were carried out in two stages. First, the main characterization analysis of the tested building stones was performed. The main technical values and parameters such as mineralogical–petrographic (polarizing microscope, XRD and SEM), chemical (XRF) and mechanical–physical properties were studied. Moreover, this study also included pore size distribution and capillary water absorption of the building stones, while their durability was investigated by means of salt crystallization tests according to TS EN 12370. Weathering tests were carried out by applying immersion–drying cycles with water containing sodium sulfate or sodium chloride. The structural changes of the building stones after the salt crystallization tests were investigated by SEM observations and ultrasonic wave measurements, while the strength properties were determined by uniaxial compressive strength tests. The highest values of dry weight loss were observed in the Ayazini tuff sample and andesite whereas the Seydiler tuff had the lowest value. The uniaxial compressive strength was 16.37% lower in the weathered samples (sodium sulfate test) compared to the fresh samples of andesite. As a result, only the Ayazini tuff was not durable and deteriorated in the environment containing sodium sulfate.

Synthesis of ZrO2 nanoparticles on pumice and tuff for sonocatalytic degradation of rifampin

ZrO2-pumice and ZrO2-tuff nanocomposites were synthesized via a modified sol–gel method and used as efficient catalysts for sonocatalytic degradation of rifampin (RIF). The physico-chemical properties of the prepared catalysts were examined using XRF, SEM, EDX, FT-IR and BET analyses and compared to pure pumice and tuff samples. Subsequently, the efficacy of catalysts in degradation of RIF was assessed under various experimental conditions. Both ZrO2-pumice and ZrO2-tuff (1.5 g L−1) exhibited promising catalytic activity for sonocatalytic degradation of RIF at its initial concentration of 20 mg L−1, natural pH and under ultrasonic irradiation power of 300 W. In this condition, about 95% and 83% of RIF was removed through US/ZrO2-pumice and US/ZrO2-tuff processes, respectively. Furthermore, the influence of the addition of a number of scavengers, enhancers and gases on the degradation of RIF was studied. The pronounced degradation effectiveness of the catalysts under ultrasound irradiation could be assigned to their synergetic ability to produce reactive species and subsequent radical reactions. The intermediate products formed in the solution from degradation of RIF were also identified and a decomposition pathway was proposed using GC–MS, COD, TOC and IC analyses.

Picrite “Intelligence” from the Middle-Late Triassic Stikine arc: Composition of mantle wedge asthenosphere

Primitive, near-primary arc magmas occur as a volumetrically minor ≤100 m thick unit in the Canadian Cordillera of northwestern British Columbia, Canada. These primitive magmas formed an olivine-phyric, picritic tuff near the base of the Middle-Late Triassic Stuhini Group of the Stikine Terrane (Stikinia). A new 40Ar/39Ar age on hornblende from a cross-cutting basaltic dyke constrains the tuff to be older than 221 ± 2 Ma. An 87Sr/86Sr isochron of texturally-unmodified tuff samples yields 212 ± 25 Ma age, which is interpreted to represent syn-depositional equilibration with sea-water. Parental trace element magma composition of the picritic tuff is strongly depleted in most incompatible trace elements relative to MORB and implies a highly depleted ambient arc mantle. High-precision trace element and Hf-Nd-Pb isotopic analyses indicate an origin by mixing of a melt of depleted ambient asthenosphere with ≤2% of subducted sediment melt. Metasomatic addition of non-conservative incompatible elements through melting of subducted Panthalassa Ocean floor sediments accounts for the arc signature of the Stuhini Group picritic tuff, enrichment of light rare earth elements (LREE) relative to heavy rare earth elements (HREE) and high field strength elements (HFSE), and anomalous enrichment in Pb.The inferred Panthalassan sediments are similar in composition to the Neogene-Quaternary sediments of the modern northern Cascadia Basin. The initial Hf isotopic composition of the picritic tuff closely approximates that of the ambient Middle-Late Triassic asthenosphere beneath Stikinia and is notably less radiogenic than the age-corrected Hf isotopic composition of the Depleted (MORB) Mantle reservoir (DM or DMM). This suggests that the ambient asthenospheric mantle end-member experienced melt depletion (F ≤ 0.05) a short time before picrite petrogenesis. The mantle end-member in the source of the Stuhini Group picritic tuff is isotopically similar to the mantle source of enriched mid-ocean ridge basalts (E-MORB) erupted today at the southern end of the Explorer Ridge in northeastern Pacific Ocean. The isotopic similarity between the Middle-Late Triassic ambient mantle under Stikinia, and mantle presently tapped at the southern Explorer Ridge suggests that enriched domains in the northeastern Pacific mantle are long-lived (≥222 million years).

Spectroscopic examinations of hydro- and glaciovolcanic basaltic tuffs: Modes of alteration and relevance for Mars

Hydro- and glaciovolcanism are processes that have taken place on both Earth and Mars. The amount of materials produced by these processes that are present in the martian surface layer is unknown, but may be substantial. We have used Mars rover analogue analysis techniques to examine altered tuff samples collected from multiple hydrovolcanic features, tuff rings and tuff cones, in the American west and from glaciovolcanic hyaloclastite ridges in Washington state and in Iceland. Analysis methods include VNIR-SWIR reflectance, MWIR thermal emissivity, thin section petrography, XRD, XRF, and Mössbauer spectroscopy. We distinguish three main types of tuff that differ prominently in petrography and VNIR-SWIR reflectance: minimally altered sideromelane tuff, gray to brown colored smectite-bearing tuff, and highly palagonitized tuff. Differences are also observed between the tuffs associated with hydrovolcanic tuff rings and tuff cones and those forming glaciovolcanic hyaloclastite ridges. For the locations sampled, hydrovolcanic palagonite tuffs are more smectite and zeolite rich while the palagonitized hyaloclastites from the sampled glaciovolcanic sites are largely devoid of zeolites and relatively lacking in smectites as well. The gray to brown colored tuffs are only observed in the hydrovolcanic deposits and appear to represent a distinct alteration pathway, with formation of smectites without associated palagonite formation. This is attributed to lower temperatures and possibly longer time scale alteration. Altered hydro- or glaciovolcanic materials might be recognized on the surface of Mars with rover-based instrumentation based on the results of this study.

A ductile to brittle shear zone–hosted Cu mineralization: Geological, geochronological, geochemical and fluid inclusion studies of the Lingyun Cu deposit, southern Tianshan, NW China

The Lingyun Cu deposit is located at the northern margin of the South Tianshan Accretionary Complex, NW China. In the Lingyun mine area, the rocks are cut by a NW–trending Yanxingshan ductile to brittle shear zone. All orebodies are hosted in crystal tuff. The sulfide mineralization in the Lingyun Cu deposit can be divided into early (E) and late (L) paragenetic stages. The E-stage is characteristic of fault-controlled sulfide assemblages (chalcopyrite + bornite+chalcocite)–quartz veins in the foliation fabric of the crystal tuff with albite + sericite ± epidote ± biotite assemblages. In the L-stage, the assemblages of ankerite + chalcopyrite + bornite + chalcocite are present in veinlets that cut the E-stage assemblages. The sulfide assemblages in the Lingyun deposit are characterized by striations in the metamorphosed crystal tuff. Ribbon-like silicate minerals in the crystal tuff share common deformation features with the sulfide assemblages.The host rock of the Lingyun Cu deposit yields a concordia age of ca. 405 Ma, indicating that the Aerbishibulake Formation formed during southward subduction of the South Tianshan Ocean beneath the Tarim Block. Moreover, crystal tuff samples show well developed negative Sr anomaly and positive Rb, Th, U, Nd and P anomalies, which are common in arc-related volcanic rocks. The ca. 297 Ma Re–Os isochron age yielded by sulfides is much younger than the host rock, which implies that the Lingyun Cu deposit is a typical epigenetic deposit. Both similar REE fractionated patterns between sulfide ores and crystal tuff and the high initial 187Os/188Os ratio (18.54 ± 0.67) indicate significant crustal materials input. The 40Ar/39Ar plateau age of ca. 292 Ma from the ribbon-like sericite in crystal tuff is coeval with the mineralization occurrence in the Lingyun Cu deposit. By contrast, diorite dikes that crosscut the crystal tuff formed at ca. 221 Ma, which is much younger than the sulfide mineralization. Thus, the mineralization in the Lingyun deposit is likely to have been generated by shear zone activity rather than the intrusion of diorite dikes.Three types of fluid inclusions have been identified in the Lingyun Cu deposit: Aqueous (W-type), mixed aqueous–carbonic (M-type) and pure carbonic (C-type) inclusions. These three types of fluid inclusions are all found in the E-stage quartz whereas only the W-type fluid inclusions have been observed in L-stage ankerite. Fluid inclusions from the E-stage commonly contain CO2 and H2O, locally with N2 with low salinity, which are common in orogenic deposits. By contrast, L-stage fluid inclusions show low CO2 concentrations and salinity, indicating a significant inflow of meteoric water. Given the regional geology, ore geology, coeval ore-forming and deformation and fluid inclusion features, the Lingyun Cu deposit may be associated with the orogenic class of mineral systems.

Sorption of benzene derivatives onto a humic acid-zeolitic tuff adduct

The sorption of some benzene derivatives: o-xylene, toluene, phenol, benzyl alcohol, resorcinol and hydroquinone onto a zeolitic tuff-humic acid adduct (PCT-ImHA) was analysed by batch technique at 25°C and neutral pH. PCT-ImHA was prepared by binding leonardite-extracted humic acids (HA) to a zeolitic tuff sample rich in phillipsite and chabazite and enriched with Ca2+ by cation exchange (Ca-PCT). The HA calcium salts were gently mixed with wet Ca-PCT; then, the mixture was heated at 330°C for 1.5h. An adduct with almost 2% of HA was obtained. The experimental data were well fitted by the Langmuir adsorption isotherm and showed that saturation capacity (qMax) increased with the octanol-water repartition coefficient (KO-W). The comparison with previous data on sorption onto immobilised HA highlights that qMax values for PCT-ImHA are far higher than the sum of the contributions of the two separate components.

Characterization of the zeolitic tuff from the “Igros-Vidojevici” deposit regarding geological and technological aspects

This study presents investigations of zeolitic tuff samples from the ?Igros- -Vidojevici? deposit. The aim of the research was to determine the quality of samples taken from all deposit parts. Thus, samples were taken from the footwall (?Zeolit 1?), and four samples from the central deposit part (?Zeolit 2?, ?Zeolit 3?, ?Zeolit 4? and ?Zeolit 5?). Characterization of the samples included chemical analysis, determination of the adsorption coefficient for methylene blue dye and cation-exchange capacity (CEC), X-ray powder diffraction analysis (XRPD), differential thermal and thermogravimetric analysis (DTA and TGA), and Fourier transform Infrared spectroscopic analysis (FTIR). Results have shown that the footwall consists mostly of clays, whereas zeolite minerals dominate in the rest of the deposit. XRD analysis of the ?Zeolit 1? sample confirmed presence of smectite and kaolinite clays, while zeolite of analcime type and quartz are present as smaller fractions. Chemical composition analysis and determination of heavy metal contents showed a significant amount (7.58%) of Fe2O3 in this sample. Therefore, further research can be pursued to find a method for removal of magnetic impurities in this deposit portion in order to utilize the clay fraction. On the other hand, according to XRD, FTIR, DTA/TGA and SEM/EDS analyses, samples which belong to the central deposit part (?Zeolit 2?5?) consist of clinoptilolite zeolite type, while clays are present in less than 10%. Thus, clays (smectites and kaolinite) accompanied with analcime and quartz are the most abundant footwall minerals while central deposit parts contain predominantly clinoptilolite accompanied with small amounts of clays. Mineragenetically, zeolites are most abundant in the ?Zeolit 2? and ?Zeolit 3? samples. The smallest value of CEC was determined for the ?Zeolit 1? sample (46.98 mmol/100g). According to CEC values determined for ?Zeolit 2? and ?Zeolit 3? (141.99 and 121.01 mmol/100 g, respectively) these samples are of the best quality, and could be utilized as adsorbents of inorganic pollutants from contaminated waters. Moreover, they could be potentially used for removal of mycotoxins from cattle feed. ?Zeolit 4? and ?Zeolit 5? samples have shown slightly lower CEC values (89.48 and 83.75 mmol/100 g, respectively), which implies lower quality, and, therefore, could be used for soil quality improvement. Finally, determination of the external CEC has revealed a significant difference between ?Zeolit 1? and ?Zeolit 5? samples (17.9 and 5.31 mmol/100 g, respectively).

Preliminary assessment, by means of Radon exhalation rate measurements, of the bio-sustainability of microwave treatment to eliminate biodeteriogens infesting stone walls of monumental historical buildings.

The main purpose of the work described in this paper has been to establish the protocol for a new non-disruptive technique of intervention, based on microwave treatment, for cleaning operations on monumental historical buildings, to eliminate biodeteriogens infesting stones. Non-destructive methods in the cleaning operations, should not only preserve the physical integrity, the chemical-mineralogical and structural identity of materials, but, when the exhalation of pollutant agents (like for example Radon gas) from building materials is considered, also, make the indoor air quality (IAQ) levels healthy. Therefore, one of the main steps of the protocol proposed in this paper is concerned with the assessment of the Radon exhalation rate in order to verify that microwave treatments do not increase the Radon naturally exhalated by building materials. In this paper, the preliminary results of the Radon measurements performed on two different type of tuff samples (grey tuff and yellow tuff), typical of the Italian traditional construction heritage, with the E-PERM passive technique at the Environmental Radioactivity Laboratory (Amb.Ra.), University of Salerno, Italy, ISO 9001:2008 certified, are summarized.

Stratigraphy, geochronology, and paleoenvironments of Miocene - Pliocene boundary of San Fernando, Belén (Catamarca, northwest of Argentina)

The Santa María-Hualfín Basin was proposed as a regional synchronous lithostratigraphic depocenter in the geological province of Northwestern Pampean Ranges, Northwestern Argentina. However, new 40Ar–39Ar dating indicates that deposits toward the east, in Santa María Valley (Santa María Department), are younger than the western depocenter in San Fernando (Belén Department). Therefore, it would be more appropriate to study these valleys as separate basins, each one with its own tecto-sedimentary features. The east basin, named in this paper Villavil-Quillay, constitutes an elongated independent basin that developed along the front of the eastern Puna bordering with Papachacra and Durazno Ranges. This basin is composed of more than 3000 m of mudstone, sandstone, conglomerates, volcaniclastic and pyroclastic deposits. Villavil-Quillay basin develops onto a peneplain of Precambrian and lower Cambrian rocks, most of which are metamorphic and granites rocks. The sedimentary fill consists of Cretaceous? and Cenozoic continental deposits. The Cenozoic record is composed of a) the Santa María Group (Miocene-Pliocene), formed by Las Arcas, Chiquimil, Andalhuala and Corral Quemado Formations, and b) the Punaschotter unit (Puna's Gravels in German, Pleistocene). This study involves the Andalhuala, Corral Quemado and Punaschotter deposits cropping out in San Fernando area. The set of identified facies assemblage corresponding to the Andalhuala Formation shows a vertical variation of fluvial sub-environments, varying from permanent sandy braided rivers to gravel rivers and aeolian dunes culminating in an alluvial dry cycle. While facies assemblages of the Corral Quemado Formation allow inferring the development of ephemeral water bodies from secondary channels on the floodplain, the Punaschotter conglomerates indicate the development of gravel channels and bars. Three samples of tuffs interbedded in the sedimentary levels of Andalhuala Formation were dated indicating that the Miocene-Pliocene boundary is represented in this area. The lower tuff beds, outcropping at the southwest of San Fernando Sur, provided an age of 5.59 ± 0.04 Ma (late Miocene, Messinian). The others tuffs beds, both outcropping at the west-northwest of San Fernando Norte and overlaying the first one, gave an age of 4.79 ± 0.15 Ma and 4.72 ± 0.08 Ma (early Pliocene, Zanclean), respectively. These absolutes ages, together with the results of a sedimentological analysis, indicate that westward from San Fernando River, much of the areas mapped as Corral Quemado Formation correspond to the Andalhuala Formation; while part of the area considered as Punaschotter unit must be assigned to Corral Quemado Formation. Also, a thick tuff bed, recognized at the contact of Corral Quemado and Punaschotter, was considered as the previous one dated in 3.66 Ma, in Puerta de Corral Quemado locality.