Aluminum Phosphate Sulfate Research Articles

Mineralogical and geochemical constraints on the origin of alunite and APS minerals from advanced argillic alteration systems: A case study from Kuh-e-Lakht Au-Ag-Cu mineralization, NE Isfahan, Iran

A significant association of alunite supergroup minerals commonly associated with quartz and pyrite is found in the Kuh-e-Lakht district of NE Isfahan, Iran. These minerals occur as pervasive alterations and within hydrothermal quartz veins. Based on field observations, microscopic studies, and geochemical analyses, the alunite subgroup exhibits noticeable variations in morphology, composition, and geochemical signatures between areas with moderate to high mineralization and those with poor mineralization. Poorly mineralized regions contain aluminum-phosphate-sulfate (APS)-free minerals of the alunite subgroup formed from steam-heated acid or supergene processes at an estimated temperature of about 200 °C, with a higher K2O than Na2O content. These crystals exhibit pseudocubic or acicular habits and zoned formations with rhythmic bands and lack APS minerals. Moderately to highly mineralized areas in Kuh-e-Lakht host tabular to platy and bladed alunite subgroup crystals with a hypogene origin, formed at around 250 °C, characterized by a higher or equal Na2O content compared to K2O. These areas also feature APS minerals with different modes of occurrence. In the southwestern, north-central, and northwestern parts, a strong genetic link with high-sulfidation minerals like pyrite, enargite, and chalcopyrite is observed. Alunite subgroup crystals with the highest Na2O/K2O ratio or equal values, as well as APS minerals with svanbergite-woodhouseite composition, occur within alunite crystals or as individual euhedral crystals exhibiting complex oscillatory zoning. These characteristics confirm a close association with the ore formation period and also the influence of higher-temperature fluids with magmatic-hydrothermal components, likely originating in closer proximity to intrusive sources. The estimated temperature for the alunite subgroup and associated ore minerals in these areas falls in the range of approximately 250 °C to 300 °C.

Marine Aluminum Phosphate–Sulfate Authigenesis as a Phosphorus Sink During Mid‐Proterozoic Oxygenation

AbstractEnhanced continental phosphorus input into the ocean has been suggested as a potential trigger for the transient oxygenation events during the mid‐Proterozoic; however, the response of phosphorus cycling to these marine oxygenations remains unclear. Here, we report the changes in phosphorus cycling associated with a ∼1.7 Ga transient oxygenation. Abundant authigenic aluminum phosphate–sulfate mineral svanbergite (SrAl3(PO4) (SO4) (OH)6; 8.02 ± 4.92 wt%) is identified within the ∼1.7 Ga Yunmengshan ironstones from the Xiong'er Basin, North China and other contemporaneous basins. This observation provides new evidence to support the suggestion that early diagenetic aluminum phosphate‐sulfate minerals could have represented a critical sink of marine phosphorus during the Proterozoic. We suggest that atmospheric oxygenation and concomitant changes in porewater redox chemistry may have enhanced the formation of early diagenetic phosphates, leading to a negative feedback on the oceanic phosphorus reservoir and atmospheric oxygen levels.

REE-bearing minerals in sediment-hosted stratiform pyrite mineralization zones of the Wiśniówka area (Holy Cross Mts., Poland)

There are two arsenical pyrite (As-FeS 2 ) mineralization zones cropping out in the Podwiśniówka and Wiśniówka Duża quarries where quartzites and quartzitic sandstones have been extracted for over a century. A large amount of pyrite in the Wiśniówka siliciclastics is unusual in the hard rock mining throughout the world. The pyritiferous beds contain a variety of REE-bearing minerals, including a crandallite series of aluminum-phosphate-sulfate (APS) minerals, e.g., predominant goyazite SrHAl 3 [(PO 4 ) 2 (OH) 6 ] with subordinate gorceixite BaHAl 3 [(PO 4 ) 2 (OH) 6 ] and very occasional crandallite CaHAl 3 [(PO 4 ) 2 (OH) 6 ]. By contrast, the other REE-phosphate minerals, e.g., xenotime YPO 4 , bur particularly monazite CePO 4 occur in a lesser amount. Goyazite prevails somewhat in the Podwiśniówka beds whereas xenotime in the Wiśniówka Duża beds. Of the other REE-bearing minerals, bastnäsite REECO 3 (F,OH), florencite (REE)Al 3 (PO 4 ) 2 (OH) 6 and synchysite CaCe[CO 3 ] 2 F occur in trace amounts. Interestingly, the quite common phosphate minerals, i.e., wavellite (Al 3 [(OH,F) 3 |(PO 4 ) 2 ]×5H 2 O and variscite Al[PO 4 ]×2H 2 O) are depleted in REEs with only Ce attaining 0.09 wt.% as documented by an electron-probe microanalysis. In contrast to quartzites/quartzitic sandstones, carbonaceous clayey-silty shales and bentonites/tuffites are distinctly enriched in REE-bearing minerals. This diversity is also mirrored in the mean total REE concentrations varying from 204 to 314 mg/kg, in clayey-silty shales and bentonites, attaining 457 mg/kg in some Podwiśniówka shale beds. Results of this and the previous petrographic, mineralogical and geochemical studies have indicated that REE-bearing minerals formed generally along with As-rich pyrite, nacrite/dickite and probably TiO 2 polymorphs as a result of multiphase hydrothermal vent activity that took place in the Wiśniówka Late Cambrian sedimentary basin. This evidence is also backed up by the values of LREE NASC /HREE NASC (1.44–1.75) and Eu/Eu NASC (1.24–1.30) coefficients in the clayey-silty shales. This positive Eu anomaly (³1.20) points to the formation of REE-bearing minerals in a reducing environment.

Mineralogical mosaics from the Carpathian-Pannonian region 5

Further mosaic-like data were recorded on the mineral occurrences of the Carpathian–Pannonian region in this fifth member of the series arranged by countries and localities. Each “mosaic” contains a concise mineral description, mainly based on XRPD, SEM-EDX and EPMA measurements and a concise description of the mineral paragenesis. Some minerals are first-time descriptions from the entire discussed region, but all are newly documented occurrences for at least the described locality. From Hungary humboldtine and weddellite are described from the coalbed of Csordakút (Bicske), and data from Sr-rich and other Aluminium Phosphate Sulphate (APS) minerals from the ore mineralization of the Lahóca Hill at Recsk are also reported. Chemical data of Mg-rich tourmaline from the Harghita volcanic ridge are given, and also kyrgyzstanite is described from the ore mineralization of Baia Sprie, Romania. From Slovakia Na-containing sulphates (kröhnkite, ferrinatrite, tamarugite) from the ore mineralization of Farbište (Poniky) and an arsenate (bariopharmacosiderite) from the ore mineralization of Rožňava are also introduced.

Hydrothermal TiO2 polymorphs in a pyrite stratiform deposit: Lessons from a mineralogical and geochemical multiproxy record

This paper presents results of mineralogical and geochemical study of TiO2 polymorphs that occur within two hydrothermal stratiform zones of the Wiśniówka area (south-central Poland). These two mineralized zones consist primarily of alternating pyritiferous and REE-bearing sedimentary quartzites, quartzitic sandstones and silty-clayey shales. Of the TiO2 phases, anatase is a predominant type (mean of 56%) with a lesser amount of rutile (30%) and mixed rutile-anatase phases (11%) as well as rare rutile-brookite (2%) and brookite (1%) as evidenced by laser Raman microspectrometry. TiO2 polymorphs typically form interstitial euhedral to anhedral or skeleton-like grains and aggregations averaging 30–50 μm in diameter occasionally attaining 110 μm. Extremely scarce pyritiferous microfossils are infilled with needle- and lath-like anatase. Under backscattered electron microscope images, TiO2 grains are generally homogenous, in places with tiny inclusions of zircon, monazite, niobium oxide and palladium telluride. In addition, some rutile grains show oscillatory zonation or zonal-brecciated and patchy patterns. Results derived from electron microprobe examinations show enrichments of most TiO2 phases in niobium (up to 4.98 wt%), zirconium (up to 0.58 wt%) and tantalum (up to 0.57 wt%) substituting titanium in the TiO2 crystal structure. The TiNb pair shows the highest correlation (r2 = 0.98). Concentrations of these and other elements vary substantially within individual anatase/rutile grains. The lack of other potential Ti-bearing rock-forming or oxide minerals (e.g., biotite, pyroxene, hornblende, titanite, ilmenite, titanomagnetite, titanohematite) in sedimentary siliciclastic rocks of the study area also indicates that anatase and rutile may have crystallized along with prevailing pyrite, xenotime, aluminum-phosphate-sulfate (APS) minerals and most monazite directly from hydrothermal fluids at relatively low temperatures, presumably around 200 °C (range of 150 to 300 °C). Among these ore minerals, only goyazite and mixed goyazite-gorceixite aggregations contain up to 20.07 wt% Ti and 24.09 wt% Ti, respectively. Mineral and microtextural relationships show that TiO2 polymorphs may have formed in two phases under reducing and subsequently oxidizing conditions of the Wiśniówka Late Cambrian depositional basin.

Indicator mineral analyses of stream-sediment samples using automated mineralogy and mineral chemistry: Applicability to exploration in covered terranes in eastern Alaska, USA

In the past two decades, significant research efforts have been devoted to porphyry copper indicator mineral (PCIM) identification and mineral chemistry to assist exploration. Such studies are important in the Yukon-Tanana upland region of eastern Alaska because well-established geochemical exploration techniques, such as the geochemistry of stream-sediment samples, are less effective in the search for mineral resources owing to cover materials that subdue geochemical signatures. The unglaciated Yukon-Tanana upland region is well-endowed with mineral resources, including porphyry Cu-Mo-Au deposits at Taurus, Bluff, Dennison, and Oreo. Using automated scanning electron microscope (SEM) techniques, numerous PCIMs have been identified in rocks and stream-sediment samples that would likely not have been observed using visual binocular microscope methods. Sulfide minerals such as chalcopyrite, chalcocite, covellite, bornite, molybdenite, and pyrrhotite were identified in rock samples, and more than half of the stream-sediment samples from drainages containing known porphyry mineral occurrences contain chalcopyrite with or without bornite. Many drainages without known occurrences also contain these minerals, which suggests potential for additional occurrences. Svanbergite, an aluminum phosphate sulfate (APS) mineral [SrAl3(PO4)(SO4)(OH)6], was identified in some of the altered or mineralized rock samples from Taurus, and in stream drainages containing porphyry occurrences and may represent the best indicator mineral for Taurus-like porphyry deposits. Apatite chemistry has great potential as a tool for assessing the presence of porphyry mineralization. Grains from rock and stream-sediment samples that contain high Cl (>∼0.4 wt%), Fe (>0.4 wt%), and Mn (>2000 ppm) clearly distinguish apatite from other sources (metamorphic, unmineralized igneous rocks). This study is one of the first to document new streamlined indicator mineral sample collection and processing methods and to combine automated SEM techniques and chemistry of minerals derived from both bedrock and surficial (stream) sediments as they apply to porphyry exploration.

LA-ICP-MS Mapping of Barren Sandstone from the Proterozoic Athabasca Basin (Canada)—Footprint of U- and REE-Rich Basinal Fluids

The Proterozoic Athabasca Basin hosts a large number of high-grade, large-tonnage unconformity-related uranium (U) deposits, many of which are also enriched in rare earth elements (REE). The basin also contains hydrothermal REE mineralization unassociated with U. Previous studies postulated that U and REE were derived from either the basin or the basement; however, the exact source of the metals remains ambiguous. This study provides evidence of U- and REE-rich fluids throughout the Athabasca Basin through laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) mapping of barren sandstone distal to mineralized areas. The results indicate that elevated U and REE concentrations mainly occur in the matrix; there are strong positive correlations between U and REE, Th, P and Sr, and moderate positive correlations between U and Zr, Ba, Fe, Al, K and Ca, but the few spots with the highest U are unrelated to these elements. Quantitative evaluation of the element correlations, together with scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) analysis, suggests that most of the elevated U and REE are hosted in aluminum phosphate sulfate (APS) minerals rather than apatite and monazite. As the APS minerals are of diagenetic-hydrothermal origin, the results testify to the presence of U- and REE-rich fluids within the Athabasca Basin. The elevated Th/U ratio (~10) and REE pattern (strong heavy rare earth element (HREE) depletion) are consistent with a model in which large amounts of U and REE (especially HREE) were leached from the sandstone within the Athabasca Basin and contributed to U and REE mineralization near the unconformity between the sedimentary rocks in the basin and underlying basement rocks. This study demonstrates that LA-ICP-MS mapping can be effectively used to evaluate microscale distribution of elements and their mobility in sedimentary rocks to address mineralization related problems.

Heterogeneity of mineral chemistry and sulfur isotopic composition of alunite in the Mankayan lithocap, northern Luzon, Philippines

The lithocap at Mankayan is a contiguous zone of alunite + quartz + pyrite that occur as pervasive alteration of the metavolcanic basement and dacitic pyroclastic rocks. Alunite + quartz + pyrite assemblage also occurs within hydrothermal gold-bearing veins and breccias. Several high-sulfidation epithermal gold orebodies have been previously delineated in the Lepanto Main Enargite orebody, and in the Northwest, Carmen, Florence West and Florence East quartz-pyrite-gold (QPG) veins. This study presents new data of mineral composition and sulfur isotopic ratios of alunites from different zones of the lithocap at Mankayan. Elemental composition maps and point analysis of alunites indicate compositional heterogeneity within a single alunite crystal. Common substituents to the K+ site are Na+ and H3O+, with few Ca2+ substitution in some sites. Limited occurrences of PO43- substitution to SO42- were also documented. Sulfur isotopic ratios (δ34SCDT) of alunite range from + 13 ‰ to + 24 ‰, which are typical of hypogene alunite. Sulfur isotopic ratios of coexisting pyrite are mostly negative, ranging from −5.4 to −1.0 ‰. Few samples of alunite from the Northwest and Florence West quartz-pyrite-gold veins have sulfur isotopic ratios similar to the values of its coexisting pyrite. The estimated temperature of formation using sulfur isotope geothermometry of alunite-pyrite pairs ranges from 197 °C to 364 °C, with most of the samples varying within 220 to 270 °C. The calculated bulk δ34S of the hydrothermal fluid was found to be + 5 to + 6 ‰ for the different mineralization events in Mankayan.The alunite crystals are heterogeneous even in the microscopic scale. Compositional maps show that K and Na concentration vary within single crystals, as well as among different crystals of a sample. The variations of K and Na content mostly follow the crystal growth structure, however, some alunite crystals with irregular variations are also present. Some samples contain aluminum-phosphate-sulfate (APS) minerals intergrown with alunite. Electron probe microanalysis of the alunite crystals showed a generally wide range of composition between the alunite – natroalunite solid solution.Using thermodynamic functions, a relationship between temperature and K+/Na+ of the hydrothermal fluids was determined across the range of alunite-natroalunite solid solution system. The model curves suggest that at temperatures less than ∼ 250 °C a slight change in fluid composition and/or temperature can vary the number of Na atoms per formula unit by 0.3 units. At higher temperatures, a more significant change in the physicochemical conditions is required for a substitution to occur. This explains the wide range of Na content in the alunites from the different parts of the lithocap.The characteristics compiled in this study reflect the fluctuations in temperature and fluid compositions that occurred during the multiple hydrothermal events in the Mankayan District.

Alteration mineralogy and pathfinder element inventory in the footprint of the McArthur River unconformity-related uranium deposit, Canada

ABSTRACTPathfinder elements associated with the exploration footprint of the McArthur River unconformity-related U deposit include U, radiogenic Pb, V, Ni, Co, Cu, Mo, As, Zn, and rare earth elements. In this study, the mineralogical and paragenetic context for their occurrence was established by integrating in situ mineral chemistry and laser ablation mass spectrometry chemical mapping of interstitial assemblages, detrital grains, and cements with whole-rock analyses of drill core samples from the diagenetically altered background and the hydrothermally altered sandstone host rocks. Diagenetically altered background sandstones contain a matrix assemblage of illite and dickite, with trace to minor aluminum-phosphate-sulfate (APS) minerals, apatite, and Fe-Ti oxide minerals. Aluminum-phosphate-sulfate minerals account for the majority of the Sr and light rare earth element concentrations, whereas early diagenetic apatite, monazite, and apatite inclusions in detrital quartz and detrital zircon contribute significant U and heavy rare earth elements to samples analyzed with an aggressive leach (partial digestion) such as aqua regia. Hydrothermally altered sandstone host rocks also contain variable assemblages of Al-Mg chlorite (sudoite), alkali-deficient tourmaline, APS minerals, kaolinite, illite, Fe-oxide, and sulfide minerals. Late pre-mineralization chlorite accounts for a significant portion of the observed Ni concentrations, whereas Co, Cu, Mo, and Zn occur predominantly in cryptic sub-micron sulfide and sulfarsenide inclusions within clay mineral aggregates and in association with Fe-Ti oxides. Elevated concentrations of U were observed in cryptic micro-inclusions associated with sulfides in quartz overgrowths, with Fe-Ti oxide micro-inclusions in kaolinite, and in post-mineralization Fe-oxide veins. The distribution of pathfinder elements throughout the deposit footprint appears to be less related to the primary dispersion of alteration minerals from the hydrothermal system than to the secondary dispersion of elements post-mineralization. Their occurrence throughout pre-, syn-, and post-mineralization assemblages further demonstrates the limitations to defining geochemical footprints from pathfinder element concentrations expressed in lithogeochemical data sets without structural, lithological, and mineralogical context.

A novel separation method of the valuable components for activated clay production wastewater

Abstract The acidic wastewater produced by the wet production of activated clay contains valuable components such as iron and aluminum. The precipitation method was successfully introduced to separate iron and aluminum from the activated clay production wastewater step by step, which can not only recover the valuable components, but also avoid environmental pollution. In the separation process, gypsum, iron aluminum phosphate, alumina, and sodium sulfate were prepared, and the phase compositions of separation products were analyzed by XRD and IR. The main influencing factors in the separation of iron and aluminum components were studied by single factor experiment. The results show that at the optimized conditions, phosphorus/iron molar ratio 6.0, the system pH 3.0, the reaction temperature 343 K, and the reaction time 90 min, the iron(iii) ion in the system can form a sodium-containing aluminum iron phosphate double salt, and the filtrate after separating Fe3+ and part of Al3+ can meet the requirements for forming high-purity Al2O3. During the phosphate precipitation process, the hypothesis should be correct that Al3+ reacts with PO 4 3 − {\text{PO}}_{4}^{3-} to form an AlPO4 skeleton, Fe3+ isomorphically replaces Al3+ in the [AlO4] tetrahedron, and adsorption occurs simultaneously, with Na+ occupying the terminal acid sites, P(Al)–OH.

Gradual changes in the Olenekian-Anisian continental record and biotic implications in the Central-Eastern Pyrenean basin, NE Spain

Abstract This work focuses on the Olenekian-Anisian (Early-Middle Triassic) continental record of the Central-Eastern Pyrenean basin (NE Spain), a near-equator (10°-14°N) basin located in the western peri-Tethys margin, inside the Variscan fold-belt. Due to the mass mortality of the end-Permian and the subsequent Smithian-Spathian Boundary (SSB) crisis, the Early Triassic and its transition to the Middle Triassic was a time period with intermittent stages of environmental instability that affected fauna and flora intensely. Compared to other crisis, a remarkable feature is the longer time required to achive life recovery during this time-interval and the fact that continental environments have been less globally studied than their marine counterparts. Furthermore, in SW Europe there is almost no sedimentary continental record from the beginning of the Triassic. This multidisciplinary study, embracing sedimentology, mineralogy, palaeontology, palaeopedology and palaeogeography, of 10 complete and well dated Early-Middle Triassic field sections has allowed (1) the location and characterization of the oldest Mesozoic sedimentary record in the basin, which is of late Smithian age and overlies the late-middle Permian continental rocks and of (2) the Smithian-Spathian transition (SST), (3) the timing of life recovery during the late Spathian-Anisian, (4) the characterization of the first incursion of the Tethys sea into the basin, and (5) the comparison of the evolution of this basin with other basins of the same age in SW Europe. The SST coincides with hyper-arid climate conditions, evolving to semi-arid in the late Spathian and semi-arid to semi-humid in Anisian times. Poorly sorted breccias and conglomerate alluvial sheets with aeolian reworking dominate the SST, as a result of these environmental changes and tectonicsA broader comparison, based on stratigraphic studies by other authors, indicates less aridity in the basin studied compared to other SW Europe basins in the same period, maybe due to its greater proximity to the equator. Sedimentary characteristics changed during the late Spathian, when sandy braided fluvial systems developed and the first dispersed plants, pollen assemblages and paleosols appeared. Well-developed floodplains and associated paleosols and plants developed during the early Anisian, when more humid conditions prevailed. The occurrence of aluminium phosphate-sulphate (APS) minerals might be considered as evidence of environmental acidification during the Olenekian with an amelioration during the early Anisian, as described in neighboring basins, although in the Pyrenean basin this acidification was probably less intensive. The first incursion of the Tethys sea reached the Central-Eastern Pyrenean basin during the Anisian-Ladinian transition, about 3 My later than in neighbouring Southwestern Europe basins. General comparison with other Early-Middle Triassic continental records of Western Europe basins indicates contrasting trends of climate and sedimentary evolution, probably related to the still prevailing great paleorelief of the Variscan foldbelt, where part of the study basin could constitute an elevated area during some time-intervals, possibly related to the so-called Ebro High.

Mineralogy and genesis of rare Al-phosphate minerals in weathered itabirite and iron ore from the Quadrilátero Ferrífero, Minas Gerais, Brazil

Phosphorus is a major deleterious element in iron ore where it occurs as primary apatite in hypogene ore, and adsorbed into Mn-, Fe-hydroxides and forming secondary phosphates in supergene ore. Secondary phosphate minerals have been formed during a long history of weathering of itabirite and hypogene iron ore in the Quadrilátero Ferrífero (QF), ongoing since the end of the Cretaceous (~70 Ma). The distribution and genesis of these secondary phosphates are poorly documented in the literature. The purpose of this study was to investigate the mineralogy, mineral chemistry and formation of rare secondary phosphate minerals found in P-bearing concretions hosted in the iron ore at the Serra do Curral, QF. Detailed mineralogical investigation revealed that three generations of secondary phosphates were formed by weathering of carbonate veins hosted within fracture zones of itabirite and iron ore. Turquoise, augelite and senegalite comprise the bulk of the secondary phosphates whereas remnants of Ca-, Ba-, Ce- and Sr-bearing minerals (crandallite, gorceixite, florencite and goyazite) are subordinated. Sulphate members of aluminium-phosphate-sulphate (APS) minerals are absent, likely due to low SO42− activities in the weathering solution. Apatite hosted within unweathered itabirite and carbonate veins was the source of P to the weathering solutions whereas Cu, Zn and Ba were released from sulphides hosted in carbonate veins and Al2O3 from country rocks. The link between the secondary phosphates to hydrothermal breccias and carbonate veins highlights the significance of hydrothermal fluids as a source of P in iron ore deposits. Furthermore, it brings attention to the structural control imposed on P-bearing minerals in these deposits. Geochemical modelling shows that the secondary phosphates were formed in response to changes in pH of the weathering fluids, providing an additional example to the literature about the application of secondary phosphate minerals as valuable trackers of paleoenvironmental weathering conditions.

Could acidity be the reason behind the Early Triassic biotic crisis on land?

In recent years there is growing evidence of the importance of the Smithian-Spathian (Early Triassic) ecological crisis to explain the delayed recovery of life after the Permian-Triassic Boundary mass extinction. This study focuses on sedimentary continental rocks of middle Permian to Middle Triassic age from four different Peritethys basins in subequatorial latitudes. Similar distribution patterns of aluminum phosphate-sulfate (APS) minerals contents in these rocks in the four studied basins provide evidence of increased acidity during the Smithian-Spathian transition, coinciding with a lack of indicators of organic activity in the same interval. Thus, this period of high acidity on land, may have been one of the causes of this biological crisis. Based on the quantification of APS minerals in the studied sedimentary sequences, we propose that it was not until acidity in the environment diminished, that biotic recovery was possible. APS data may also be useful to interpret other past biotic crises.

Mineralogical Study of the Advanced Argillic Alteration Zone at the Konos Hill Mo–Cu–Re–Au Porphyry Prospect, NE Greece

The Konos Hill prospect in NE Greece represents a telescoped Mo–Cu–Re–Au porphyry occurrence overprinted by deep-level high-sulfidation mineralization. Porphyry-style mineralization is exposed in the deeper parts of the system and comprises quartz stockwork veins hosted in subvolcanic intrusions of granodioritic composition. Ore minerals include pyrite, molybdenite, chalcopyrite, and rheniite. In the upper part of the system, intense hydrothermal alteration resulted in the formation of a silicified zone and the development of various advanced argillic alteration assemblages, which are spatially related to N–S, NNW–SSE, and E–W trending faults. More distal and downwards, advanced argillic alteration gradually evolves into phyllic assemblages dominated by quartz and sericite. Zunyite, along with various amounts of quartz, alunite, aluminum phosphate–sulfate minerals (APS), diaspore, kaolinite, and minor pyrophyllite, are the main minerals in the advanced argillic alteration. Mineral-chemical analyses reveal significant variance in the SiO2, F, and Cl content of zunyite. Alunite supergroup minerals display a wide compositional range corresponding to members of the alunite, beudantite, and plumbogummite subgroups. Diaspore displays an almost stoichiometric composition. Mineralization in the lithocap consists of pyrite, enargite, tetrahedrite/tennantite, and colusite. Bulk ore analyses of mineralized samples show a relative enrichment in elements such as Se, Mo, and Bi, which supports a genetic link between the studied lithocap and the underlying Konos Hill porphyry-style mineralization. The occurrence of advanced argillic alteration assemblages along the N–S, NNW–SSE, and E–W trending faults suggests that highly acidic hydrothermal fluids were ascending into the lithocap environment. Zunyite, along with diaspore, pyrophyllite, and Sr- and Rare Earth Elements-bearing APS minerals, mark the proximity of the hypogene advanced argillic alteration zone to the porphyry environment.

Optimized preparation of PPFAS and removal of heavy metals

The basification method was used for the optimized preparation of a new flocculant, poly‐ferric aluminum phosphate sulfate (PPFAS). The Ferron method was used to analyze the distributions of the Fe and Al forms in PPFAS. The conditions of the optimized preparation of PPFAS were as follows: the n(OH)/n(Fe) ratio of 0.6, the n(P)/n(Fe) ratio of 1/5, and the reaction temperature of 60°C. After each addition of NaOH and Na3PO4, the reaction was allowed to proceed for 10 min, and then, the reaction continued on the shaking table for 1 h; the aging process continued for 60 h at 25°C. Under these conditions, the content of the effective component, [Fe + Al]b, could reach up to 60%. The order of the removal rates of the mixed heavy metals by PPFAS is Cu(II)> Cr(III)> Pb(II)> Zn(II)> Cd(II). The order of the removal rates of the mixed complex heavy metals is EDTA‐Cd(II)> EDTA‐Zn(II)> EDTA‐Pb(II)> EDTA‐Cu(II)> EDTA‐Cr(III). © 2017 American Institute of Chemical Engineers Environ Prog, 37: 240–248, 2018

Climatic instability before the Miocene Climatic Optimum reflected in a Central European lacustrine record from the Most Basin in the Czech Republic

The work investigates the extensive freshwater lacustrine deposits of the Most Formation, which formed in the period between 17.7Ma and ca. 15.9Ma, in order to describe climate changes just before the Miocene Climatic Optimum (MCO). The Most Basin, an incipient rift within the European Cenozoic Rift System, exhibited a sedimentary environment that was sufficiently stable to preserve orbital signatures of environmental changes. Changes in the mineral composition of the sediments were characterised in terms of variations in their elemental composition, particularly their Al/Si and K/Ti element ratios and Fe, Sr, and Zr elemental abundances, which were efficiently obtained using X-ray fluorescence spectroscopy with a density of 3–4 samples per metre of core (approximately 15–20 samples per precession cycle). The sediments are distinguished by the presence of distinct and correlated horizons (1–10cm thick) containing Sr, Ba-rich crandallite, a mineral from the aluminium-phosphate-sulphate (APS) group. Chemo-, magneto-, and cyclostratigraphy were used to correlate eight cores with lengths up to 240m and to date the sediment; discrepancies at scales of up to two precession cycles (each ca. 20kyr, typically ~4m per cycle) were observed. The primary age model was based on magnetic polarity analysis (5 reversals) and later refined at the metre scale using cyclostratigraphy. We interpret the onset of the basin-wide lacustrine phase in the Most Basin as being a consequence of the enhanced input of fluvial clastic sediment to the former peat swamps during the high-eccentricity period at 17.7–17.55Ma, i.e., immediately after the initial decay of the East Antarctic ice sheet according to Levy et al. (2016). The most important environmental change recorded by the lacustrine interval in the Most Basin occurred at 16.44Ma during an eccentricity maximum and is nearly coeval with further shrinkage of the East Antarctic ice sheet. The second stage of monotonous lacustrine deposition, which exhibited enhanced precession-controlled compositional variability in 16.1–16.0Ma witnessed the onset of the MCO. Sediments younger than 15.9Ma are missing due to erosional removal after subsequent basin inversion. The sediments of the Most Formation represent an archive of environmental change in central Europe during the early stages of the MCO and have a temporal resolution ca. 5kyr.

Geochemistry of advanced argillic altered rocks in the area of Breznik, Western Srednogorie Unit (Bulgaria)

The distribution and behaviour of major and trace elements in the main zones of hydrothermal alteration (propylite, sericite and advanced argillic) in the area of Breznik Town have been studied, coupled with the chemical composition of alunite group minerals and their isotope geochemistry. The content of Sr decreases in propylite and especially in sericite rocks, and increases significantly in advanced argillic altered (AAA) rocks, which is connected with the formation of aluminium phosphate-sulphate (APS) minerals. Rubidium has high content in sericitic rocks, whereas the element is almost depleted in AAA rocks. The Rb/Sr ratio increases in sericitic rocks and strongly decreases in AAA rocks. Zirconium, Ti, Cr, V, Ga, Hf, Nb, Ta, Th, U and partially Sn and Ba have comparatively inert behaviour during alteration. Manganese, Zn, Ni, Co, Cs and Y are mobile in different degree, with a trend toward complete extraction in the most altered rocks. Arsenium concentrates in AAA rocks, while Li is concentrated only in kaolinite AAA rocks. LREE are comparatively inert in AAA rocks, while MREE and HREE are very mobile, especially in alunite rocks. Alunite has Na-K composition, with permanent admixtures of Ca, Sr, Ba and LREE. APS minerals themselves are woodhouseite and svanbergite-woodhouseite solid solutions (s.s.). Stable isotopes of alunite are characteristic for magmatic-hydrothermal alunite, whereas δ34S of jarosite is intermediate between δ34S of alunite and sulphides, which confirms its supergene origin. All these features define a high-sulphidation epithermal environment, and a possible porphyry mineralization at deeper part of the system is suggested.

Characterizing fluids associated with the McArthur River U deposit, Canada, based on tourmaline trace element and stable (B, H) isotope compositions

The origin and nature of fluids responsible for U deposits of the Athabasca Basin have been in debate. This study presents the trace element abundances and stable isotope ratios (D/H and 11B/10B) of well characterized tourmaline samples determined by in situ analytical techniques, in order to evaluate the nature of fluids during the mineralization of the McArthur River U deposit, the world's largest high-grade U deposit. Magnesio-foitite, an alkali-deficient Mg-rich tourmaline, is abundant along the 13-km long P2 fault, a reverse structure that controls the location of the McArthur River deposit. Magnesio-foitite contains variable concentrations of rare earth elements (REEs, up to 46ppm in total) and Y (up to 35ppm). Chondrite normalized patterns indicate low light REEs (LREEs) relative to heavy REEs (HREEs) (CeN<YN, Y as a proxy for HREEs) and slight negative Eu anomalies, similar to those of uraninite from the deposit. The data combined with textural evidence suggest that magnesio-foitite and uraninite co-crystallized with LREE-rich aluminum phosphate sulfate minerals. Relatively high REE contents of magnesio-foitite in the ore zone indicates the incursion of a REE-rich basement fluid. Low values of δD (−98 to −41‰) for magnesio-foitite suggests that the mineralizing fluid originated from groundwater. Variably high values of δ11B (+13.1 to +23.2‰) are explained by the dissolution of B from carbonate or evaporitic rocks and preferential removal of 10B by the crystallization of illite and kaolinite. The results of this study support the ascent of a REE-rich basement fluid during mineralization and extensive modification of basinal fluids through the crystallization of clay minerals.

Zonation of Sulfate and Sulfide Minerals and Isotopic Composition in the Far Southeast Porphyry and Lepanto Epithermal Cu–Au Deposits, Philippines

AbstractThe world‐class Far Southeast (FSE) porphyry system, Philippines, includes the FSE Cu–Au porphyry deposit, the Lepanto Cu–Au high‐sulfidation deposit and the Victoria–Teresa Au–Ag intermediate‐sulfidation veins, centered on the intrusive complex of dioritic composition. The Lepanto and FSE deposits are genetically related and both share an evolution characterized by early stage 1 alteration (deep FSE potassic, shallow Lepanto advanced argillic‐silicic, both at ~1.4 Ma), followed by stage 2 phyllic alteration (at ~1.3 Ma); the dominant ore mineral deposition within the FSE porphyry and the Lepanto epithermal deposits occurred during stage 2. We determined the chemical and S isotopic composition of sulfate and sulfide minerals from Lepanto, including stage 1 alunite (12 to 28 permil), aluminum–phosphate–sulfate (APS) minerals (14 to 21 permil) and pyrite (−4 to 2 permil), stage 2 sulfides (mainly enargite–luzonite and some pyrite, −10 to −1 permil), and late stage 2 sulfates (barite and anhydrite, 21 to 27 permil). The minerals from FSE include stage 2 chalcopyrite (1.6 to 2.6 permil), pyrite (1.1 to 3.4 permil) and anhydrite (13 to 25 permil). The whole‐rock S isotopic composition of weakly altered syn‐mineral intrusions is 2.0 permil.Stage 1 quartz–alunite–pyrite of the Lepanto lithocap, above about 650 m elevation, formed from acidic condensates of magmatic vapor at the same time as hypersaline liquid formed potassic alteration (biotite) near sea level. The S isotopic composition of stage 1 alunite–pyrite record temperatures of approximately 300–400°C for the vapor condensate directly over the porphyry deposit; this cooled to &lt;250°C as the acidic condensate flowed to the NW along the Lepanto fault where it cut the unconformity at the top of the basement. Stage 1 alunite at the base of the advanced argillic lithocap over FSE contains cores of APS minerals with Sr, Ba and Ca; based on back‐scattered electron images and ion microprobe data, these APS minerals show a large degree of chemical and S‐isotopic heterogeneity within and between samples. The variation in S isotopic values in these finely banded stage 1 alunite and APS minerals (16 permil range), as well as that of pyrite (6 permil range) was due largely to changes in temperature, and perhaps variation in redox conditions (average ~ 2:1 H2S:SO4). Such fluctuations could have been related to fluid pulses caused by injection of mafic melt into the diorite magma chamber, supported by mafic xenoliths hosted in diorite of an earlier intrusion.The S isotopic values of stage 2 minerals indicate temperatures as high as 400°C near sea level in the porphyry deposit, associated with a relatively reduced fluid (~10:1 H2S:SO4) responsible for deposition of chalcopyrite. Stage 2 fluids were relatively oxidized in the Lepanto lithocap, with an H2S:SO4 ratio of about 4. The oxidation resulted from cooling, which was caused by boiling during ascent and then dilution with steam‐heated meteoric water in the lithocap. This cooling also resulted in the sulfidation state of minerals increasing from chalcopyrite stability in the porphyry deposit to that of enargite in the lithocap‐hosted high‐sulfidation deposit. The temperature at the base of the lithocap during stage 2 was ≥300°C, cooling to &lt;250°C within the main lithocap, and about 200°C towards the limit of the Lepanto orebody, approximately 2 km NW of the porphyry deposit. Approximate 300°C and 200°C isotherms, estimated from S isotopic and fluid inclusion temperatures during stage 1 and stage 2, shifted towards the core of the FSE porphyry deposit with time. This general retreat in isotherms was more than 500 m laterally within Lepanto and 500 m vertically within FSE as the magmatic–hydrothermal system evolved and collapsed over the magmatic center. During this evolution, there is also evidence recorded by large S isotopic variations in individual crystals for sharp pulses of higher temperature, relatively reduced fluid injected into the porphyry deposit.

Composition of Large Zoned Aluminum Phosphate Sulfate Minerals: Implications For Fluid Evolution In the Centennial Uranium Deposit Area, Athabasca Basin, Saskatchewan, Canada

Abstract Aluminum phosphate sulfate (APS) minerals associated with the Athabasca Basin are compositionally part of the alunite group. Typically 5–20 μm in size, they accompany the regional diagenetic-hydrothermal illite-kaolinite-dickite assemblage in the Athabasca Group sandstones, the illite-sudoite assemblage of the altered paleo-regolith, and alteration zones surrounding uranium deposits. In the vicinity of the Centennial deposit, where illite and sudoite replace coarse-grained aluminosilicate porphyroblasts in the basement phyllitic pelites, cubic APS crystals are as large as 80 μm. Detailed petrography indicates that the APS crystals form broadly coeval to illite. Backscattered electron imaging, elemental mapping, and compositional analysis reveal complex zoning as well as later hydrothermal alteration of the APS crystals. Growth-zoned crystals are a solid solution between crandallite-goyazite-svanbergite [Sr 0.17–0.32 Ca 0.0.18–0.28 LREE 0.0.25–0.46 (Al 2.78–2.92 Fe 0.01–014 )(PO 4 ) 1.82–2.03 (SO 4 ) 0.14–0.35 (OH) 6 ], whereas the later alteration of the APS minerals results in a compositional shift to endmember florencite [Sr 0.15 Ca 0.11 LREE 0.57 (Al 2.86 Fe 0.02 )(PO 4 ) 1.98 (SO 4 ) 0.15 (OH) 6 ]. Fluids responsible for the alteration of APS to florencite are paragenetically linked to late hydrothermal fluids associated with mafic Mackenzie dikes and do not appear to be related to proximity to uranium mineralization. Both zoned and altered portions of the crystals have bulk compositions that overlap with APS minerals in other areas of the basin suggesting a common genetic origin. However, it is critical to link the paragenetic context to observed compositional changes. An increase in MREE from early to late stages of zoned crystal growth correlates with the greatest concentration of REE found in uraninite from unconformity-related uranium deposits. This could be a link between broader APS growth and uraninite precipitation.