Mineral Suite Research Articles

Quantification of modal mineralogy in molybdenite-bearing drill-core samples by laser-induced breakdown spectroscopy.

Quantification of modal mineralogy in drill-core samples is crucial for understanding the geology and metal deportment in a mining operation. This study assesses conventional procedures to quantify modal mineralogy, that includes an initial drill-core logging, followed by petrographic descriptions and SEM-based automated mineralogy analyses performed in selected regions of interest, against a novel approach using laser-induced breakdown spectroscopy (LIBS). Our proposed methodology aims to quantify the modal mineralogy directly in a drill-core sample, avoiding previous stages of selection and preparation of samples. The novelty of our methodology lies in the simultaneous selection of spectral signals corresponding to a group of elements that are interrelated within a mineral species. The resulting signal combination is strongly correlated with a mineral found in the sample. Our proof of concept combines previously described mineralogy with a detailed spectroscopic and principal component analysis. The selected spectral signals are defined as "mineralogical patterns", which are processed using supervised chemometrics methods, such as artificial neural networks, to enable an automated mineral classification. We implemented our workflow in three molybdenite-bearing drill-core samples, yielding results comparable to operational characterization, based on petrographic studies, and validated by QEMSCAN analyses, for a suite of ore and gangue minerals, including molybdenite, pyrite, hematite/magnetite, quartz, and aluminosilicates. In brief, we demonstrate how the LIBS-ANN technique can perform automated mineral quantification directly in selected drill-core regions of interest, minimizing previous sample preparation and without expert judgment.

Application of pre-magnetic separation to address grinding classification density effects and enhance iron-copper separation in deep polymetallic magnetite ores

This study investigates the challenges faced in the grinding and classification process of a polymetallic magnetite ore from Anhui, particularly focusing on low classification efficiency, significant over-grinding, and decreased metal recovery rates. By analyzing the mineralogical properties of the ore, specifically mineral composition, intergrowth relationships, intergrowth particle size, and liberation degree, with an emphasis on magnetite, chalcopyrite, cobalt minerals, and precious metal minerals, this research aims to identify the underlying causes of these issues. Subsequent single-factor experiments were conducted to assess the effects of magnetic field strength and grinding parameters on the enrichment of magnetite and chalcopyrite. Under optimal processing conditions, with a magnetizing current of 0.25 A and a grinding fineness of 65% passing through a 200-mesh sieve, the application of butyl xanthate as a collector during mixed rough flotation achieved a copper recovery rate of 89.54%. Building on these findings, the study further discusses the impact of various process flow optimizations on grinding, classification operations, and the recovery of target minerals. Additionally, it evaluates the advantages and disadvantages of different processing methods in practical applications and ultimately proposes a suitable mineral processing flow for intermediate to deep ore deposits.

Analyzing the role of coastal geomorphology on heavy mineral distribution along a coastal tract of Kerala, southwest India

A multitemporal morphological and heavy mineral study was conducted on the coastal area of the southwest coast of Kerala, India between two major rivers namely Chandragiri River and Karingotte River. The study revealed an interesting distribution pattern of heavy minerals in the area. An offshore fault and a minor river, Chithari River on land, divided the area into two sectors, namely sector-1 and sector-2. Sector-1, located north of the river, is characterized as a submerging coast and exhibits erosion, while sector-2, located south of the river, is characterized as an emerging coast and exhibits accretion. The study found that the total heavy mineral concentration in the area ranged from 2.9 wt.% to 37 wt.%, with an average of 13.65 wt.% in sector-2 and 7.38 wt.% in sector-1. This difference in heavy mineral concentration is reflected in the iso-concentration map, which shows that sediment in sector-2 is more enriched with heavy minerals. Furthermore, the mineralogy of the heavy mineral suite also differs between the two sectors, with sector-1 dominated by ilmenite-garnet-sillimanite suite and sector-2 dominated by garnet-ilmenite-sillimanite suite. Though the unique distribution of heavy mineral placers in the two sectors is influenced by factors such as geology, geomorphology, and surface and subsurface structural features in the area, the distribution and concentration of heavy minerals in the area were found to be influenced more by coastal geomorphology. Hence this study highlights the importance of considering coastal geomorphology in understanding the distribution and concentration of heavy mineral placers.

Calorimetry and structural analysis of uranyl sulfates with rare topologies

Abstract Uranyl sulfate minerals are the most rapidly expanding group of uranium minerals, with dozens of species described in the past decade from the localities of White Canyon, U.S.A. and Jáchymov, Czech Republic. Synthetic analogs of a suite of uranyl sulfate minerals were crystallized, characterized, and the standard-state enthalpies of formation (ΔHfo) were determined. Synthetic lussierite is monoclinic, space group Cc, a = 9.2896, b = 28.685, c = 9.6155 Å, β = 93.504°. Synthetic geschieberite is ortho-rhombic, space group Pna21, a = 13.7408, b = 7.2713, c = 11.5844 Å. The standard-state enthalpies of formation from the binary oxides for lussierite, péligotite, shumwayite, geschieberite, and bluelizardite are –3214 ± 78, –2026 ± 33, –587 ± 22, –966.1 ± 10.9, and –2084 ± 21 kJ/mol, respectively, while the standard-state enthalpies of formation of each phase from its elements are –9743 ± 78, –7220 ± 33, –5255 ± 22, –3916 ± 20, and –7117 ± 21 kJ/mol, respectively. The ΔHfo of péligotite was accurately estimated using the ΔHfo of lussierite, bluelizardite, and literature values of the oxide components of each phase. This implies that estimates can be made accurately of the ΔHfo of uranyl sulfates of minerals without synthetic analogs.

Heavy Minerals Distribution and Provenance in Modern Beach and Fluvial Sands of the Betic Cordillera, Southern Spain

This study uses heavy detrital minerals to determine actualistic fluvial and beach sand provenance across the Betic Cordillera (Spain), along the coast from Almeria to Marbella. The Betic Cordillera, primarily composed of metamorphic rocks to the east, supply an assemblage dominated by almandine and graphite, with a longshore dispersal from Almeria to Malaga. Buergerite and hypersthene indicate the provenance of calcalkaline lavas east of Cabo de Gata. The western part of the Betic Cordillera, which comprises the Ronda Peridotite Complex, supplies a chromite and diopside assemblage, with a dispersal from Marbella to Algeciras. Considering these mineralogical suites, the effects of source rock compositions and weathering are evaluated. The heavy mineral species mirror the mineralogy of the source rocks of local outcrops and wider source terranes. The fluvial heavy mineral suites do not differ significantly from those in the beaches except for some unstable species. Unstable species such as olivine, pyroxene, and amphibole do not show evidence of loss because of elevated topography and semiarid climate, which do not affect heavy minerals. This contribution also evaluates the potential of some heavy detrital species as ideal pathfinders in searching for diamonds.

Phytochemical and Mineral contents of Croton Sparsiflorus in Bahawalpur

Although a huge quantity of plants has been studied for their medicinal importance, there is still a large number of plant species that have never been subjected to systematic phytochemical studies, proximate or mineral contents analysis. In this study, a phytochemical analysis, proximate, and mineral contents investigations have been carried out on indigenous medicinal plant of Pakistan namely Croton sparsiflorus Morong (syn. Croton bonplandianum Baill.) The proximate and phytochemical compositions of Croton sparsiflorus were investigated following standard procedures. The mineral composition was determined by atomic absorption spectrophotometer and a flame photometer. The result indicated the healthy mineral level of Croton sparsiflorus. It showed a considerable amount of Zinc (49.2 ppm), Iron (333.6 ppm), Manganese (7.6 ppm), and Copper (23.14 ppm). Phytochemical studies of Croton sparsiflorus confirmed the presence of alkaloids, flavonoids, saponins, phenols, proline, and carbohydrates in varying concentrations. The proximate analysis showed that the dry contents of Croton sparsiflorus were 98.95%. The moisture content in the dry sample was found to be 0.73%. The crude protein (crude protein included both true protein and nonprotein nitrogen) content was 10.63%. This study is another confirmation of the earlier stated facts that this plant is a good source for bio-prospecting. The study further revealed that the plant, Croton sparsiflorus used has substantiated to be very essential in medical research and development, because of the phytochemicals that are contemporaneous and can be utilized in the medical field. Twigs, leaves, roots, stem, and inflorescence of Croton sparsiflorus seem to have good nutritious, and suitable mineral elements worth crucial to preserve good well-being.

Geology and genesis of the Aqishan Pb-Zn deposit, NW China: Insights from mineralogy, geochemistry, and in situ U-Pb geochronology

The unique ore-forming processes and the key factors responsible for formation of skarn deposits are still obscure, and challenges exist in the determination of timing of Pb-Zn skarns owing to lacking suitable mineral chronometers. Here we present detailed paragenesis, bulk geochemistry, in situ U-Pb dating of zircon and garnet, and garnet oxygen isotopes together with in situ zircon Hf-O isotopes from the newly discovered Aqishan Pb-Zn deposit in the southern Central Asian Orogenic Belt (CAOB), northwest China. This comprehensive data set revealed a Late Carboniferous subduction-related distal Pb-Zn skarn system associated with the granitic magmatism. Pre-ore stage garnets are generally subhedral to euhedral with oscillatory zoning and show slightly fractionated rare earth element patterns with positive Eu anomalies that point to an infiltration metasomatism origin under high water/rock ratios. The syn-ore stage sphalerite is typically enriched in Mn and Cd and has moderate Zn/Cd ratios (337–482), with a formation temperature of 265 °C to 383 °C, which indicate magmatic-hydrothermal signatures. The isocons defined by P2O5 decipher that the principal factors for skarn formation were elevated activities of Fe, Ca, and Si species, where remobilization of Pb metals, meanwhile, contributed to ore-forming budgets to mineralizing fluids. SIMS U-Pb dating of zircons from granite porphyry that occurs distal to the skarns and Pb-Zn orebodies shows that these intrusions emplaced at ca. 311.3–310.6 Ma, recording the subduction of the Paleo-Tianshan oceanic plate. Hydrothermal garnets in close textural association with Pb-Zn sulfides yield indistinguishable in situ LA-ICP-MS U-Pb ages of 310.5 ± 4.1 Ma. Whole-rock geochemistry and in situ zircon Hf-O isotopes (δ18O = 4.6‰–6.0‰) indicate that the granite porphyry was derived from partial melting of juvenile crust and influenced by subducted oceanic crust. Oxygen isotope compositions of garnets (δ18O = 8.0‰–9.0‰) demonstrate that the equilibrated ore fluids were inherited from fluid-rock interactions between a primary magmatic water and host tuff rocks. Our study highlights the application of garnets as a potential robust U-Pb geochronometer and isotopic tracer of ore fluids in skarn mineralizing systems in subduction-related arc environments.

A speleogenetic history of Novoafonskaya Cave in the Western Caucasus

Speleogenesis in hypogene karst settings may be closely tied to regional tectonic dynamics and concomitant hydrochemical evolution of karst waters. However, placing temporal constraints on these processes can require a wider array of field observations and techniques than for typical karst systems. Herein, we present a comprehensive study of Novoafonskaya Cave (Western Caucasus, Abkhazia). The updated speleogenetic history of the cave comprises four stages: (1) the most ancient, a low-T hydrothermal (ca. 40–50°C) priming stage; (2) the main stage enabled by mixing of upwelling thermomineral and locally recharged common karst waters; (3) the late sulfuric-acid speleogenesis (SAS) stage, which left significant mineralogical overprint (gypsum and a suite of minerals resulting from the alteration of silicate sediments) but did not alter the morphology of the cave appreciably; and (4) the contemporary stage, occurring predominantly in the phreatic and epiphreatic zones. Ages of speleogenetic stages were constrained by radiometric dating (230Th-U and 40Ar/39Ar) and paleomagnetic data, alongside the Quaternary geological history of the region and paleodynamics of the Black Sea level. Conditions for the low-T hydrothermal karstification occurred from Miocene – Middle Pliocene. The main stage, which created the main volumes of the cave, took place from Late Pliocene – Middle Pleistocene. The cave emerged from the phreatic into the vadose zone after ca. 400 ka ago, due to the combined effect of the Black Sea regression and intensification of tectonic uplift in the Caucasus. The presence of sulfidic waters during dewatering led to the development of transient SAS processes during Middle to Late Pleistocene. Dating of calcite underlying SAS-associated overgrowths constrains the cessation of this SAS activity to within the last 147 ka. In its present state, the cave has no connection with thermomineral waters; however, such waters are found deeper in the southern parts of the karst massif (based on the hydrochemistry of Psyrtskha spring), implying that hypogene karstification, primarily driven by mixing corrosion, may still be active deep in the phreatic zone.

Manufacture of Low-Na White Soft Brined Cheese: Effect of NaCl Substitution with a Combination of Na-K Salts on Proximate Composition, Mineral Content, Microstructure, and Sensory Acceptance.

All over the world, especially in Western societies, table salt intake that is inordinately higher than the acceptable level has been observed. An excess of Na in the human diet, mostly from processed foods, is becoming the "number one killer", leading to increased blood pressure. Therefore, the food industry is faced with a need to reduce Na in human nutrition in an effort to raise public health protection to a higher level. In this study, a commercially available combination of Na/K salts (COMB) at different concentrations was used as a NaCl substitute in the production of a modified, healthier, Na-reduced cheese. Samples of the modified low-Na white soft-brined cheese (WSBC) were produced by adding four different concentrations of COMB to production lots PL-1 to PL-4, and the control (CON) samples were prepared by salting with the usual, non-reduced concentration of NaCl. The effects of NaCl replacement on the physical-chemical parameters, major- and micro-elements, and microstructural and sensory properties of the WSBC were investigated. The obtained results indicated that there was no significant influence on the ash content, pH, and aw. The Na and K levels differed among treatments (p < 0.001). The lowest Na level in this study was recorded in PL-4 (only COMB was added) and was 334.80 ± 24.60 mg/100 g. According to the Na content, WSBC PL4 can be labeled with the nutrient claim "reduced amount of Na". A significant difference (p < 0.05) was noticed in overall acceptance between the CON and PL-4, with no statistically significant difference found amongst other WSBC production lots. The replacement of NaCl resulted in a slightly greater firmness of the WSBC. The results confirm the possibility of producing low-Na WSBC when optimal amounts of a suitable mineral salt are used as a substitute for NaCl, thus reducing the risk of high Na intake in the human body through the consumption of evaluated cheese.

Strontium-Doped Bioglass-Laden Gelatin Methacryloyl Hydrogels for Vital Pulp Therapy.

This study aimed to develop gelatin methacryloyl (GelMA)-injectable hydrogels incorporated with 58S bioactive glass/BG-doped with strontium for vital pulp therapy applications. GelMA hydrogels containing 0% (control), 5%, 10%, and 20% BG (w/v) were prepared. Their morphological and chemical properties were evaluated by scanning electron microscopy/SEM, energy dispersive spectroscopy/EDS, and Fourier transform infrared spectroscopy/FTIR (n = 3). Their swelling capacity and degradation ratio were also measured (n = 4). Cell viability (n = 8), mineralized matrix formation, cell adhesion, and spreading (n = 6) on DPSCs were evaluated. Data were analyzed using ANOVA/post hoc tests (α = 5%). SEM and EDS characterization confirmed the incorporation of BG particles into the hydrogel matrix, showing GelMA's (C, O) and BG's (Si, Cl, Na, Sr) chemical elements. FTIR revealed the main chemical groups of GelMA and BG, as ~1000 cm-1 corresponds to Si-O and ~1440 cm-1 to C-H. All the formulations were degraded by day 12, with a lower degradation ratio observed for GelMA+BG20%. Increasing the concentration of BG resulted in a lower mass swelling ratio. Biologically, all the groups were compatible with cells (p > 0.6196), and cell adhesion increased over time, irrespective of BG concentration, indicating great biocompatibility. GelMA+BG5% demonstrated a higher deposition of mineral nodules over 21 days (p < 0.0001), evidencing the osteogenic potential of hydrogels. GelMA hydrogels incorporated with BG present great cytocompatibility, support cell adhesion, and have a clinically relevant degradation profile and suitable mineralization potential, supporting their therapeutic potential as promising biomaterials for pulp capping.

Textural Attributes and Mineralogy of River Forcados Floodplain Sediments along Patani and Environs

River Forcados floodplain sediments were collected along Patani and environs from five locations at depths 0 m, 5 m, 10 m and 15 m in order to study their textures and mineralogy. Textural attributes were derived from grain size analysis using mechanical sieving and graphical determination of statistical parameters. Oxide analysis from the bulk chemistry using XRF was used to study the mineralogy of the sediments. The grain size range from very coarse sand to clay deposits with the modal class in the fine silt grade in all the locations. The sediment load represents traction, saltation and suspension modes of transportation deposited during several cycles of flooding by fluctuating high and low energy regimes. The average mean (M) is 4.89 (very coarse silt size grade), the average median is 5.27 (coarse silt grade), the average sorting (σ) is 1.86 (poorly sorted), they are negatively skewed on the average with a value of -0.29 and are very leptokurtic with an average value of 1.80. The sediment is enriched in SiO2, Al2O3, Fe2O3, K2O, TiO2, CaO and Cl with values 75.39%, 9.98%, 5.09%, 4.20%, 1.44%, 1.26% and 1.02% respectively. The SiO2/Al2O3 ratio has an average value of 8.281 which shows the sediment is rich in silica and has an acid igneous rock source. The enrichment in K2O also corroborates an acid igneous source. The mineral suite indicates the soil in the studied floodplain is rich in nutrients and is fertile for use by both plants and animals

In situ U-Pb isotopic dating method on titanite, and application to determine REE-Fe-Cu mineralization age of the Sin Quyen deposit, Lao Cai province

Titanite (CaTiSiO5) is an important common accessory mineral in hydrothermal deposits, with appreciable amounts of U and Th incorporated into their structures for age dating. Titanite crystals are usually larger than zircon and monazite and may have zoning in texture and geochemistry which represent different parageneses likely related to multiple hydrothermal or mineralization events. In line with the development of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) that has high sensitivity and spatial resolution, in-situ U-Pb isotopic dating method on titanite has become a powerful tool to investigate the ages of different zones from a mineral. Titanite typically accommodates a significant amount of Rare Earth Elements (REEs) and High Field Strength Elements (HFSEs) and the titanite generated from different origins exhibits distinct trace element geochemistry. Therefore, the trace element geochemistry of titanite can serve as an indicator of its formation environment. Titanite occurred in different mineralization stages of the Sin Quyen deposit, making it a suitable mineral for investigating the timing of mineralization. In this paper, we present the U-Pb age of titanite from different stages of the Sin Quyen deposit used to constrain the timing and origin of such events. The hydrothermal titanites are dated by in situ LA-ICP-MS technique and have U-Pb ages of 873±12 Ma and 844±12 Ma which indicate two mineralization/hydrothermal events at the same time, respectively. These ages from the Sin Quyen deposit are well correlated with regional tectono-thermal events during the long-lived Neoproterozoic subduction in the western Yangtze Block.

Barite, Anhydrite and Gypsum Reference Materials for In Situ Oxygen and Sulfur Isotope Ratio Measurements

Secondary ion mass spectrometry was used to test the δ18O and δ34S nanogram‐scale homogeneity of a suite of candidate sulfate minerals, ultimately selecting three barite, two anhydrite, and two gypsum samples from the Royal Ontario Museum that have repeatabilities for their SIMS measurements of better than ±0.39‰ and ±0.37‰ (1s) for oxygen and sulfur isotope ratios, respectively. Metrological splits of each of the seven materials were sent to multiple gas source isotope ratio mass spectrometry laboratories in order to establish their absolute 18O/16O and 34S/32S ratios. The inter‐laboratory results of GS‐IRMS analyses yielded reasonably narrow ranges in δ18OVSMOW, whereas larger variations in δ34SVCDT values were found between the results from the gas source laboratories. All samples have good reproducibility within laboratories of GS‐IRMS 103δ18O values of between ±0.24‰ and ±0.44‰ (1s). The reproducibility within laboratories of GS‐IRMS 103δ34S values range from ±0.07‰ to ±0.99‰ (1s). Here we also discuss some of the current analytical limitations affecting these isotope‐mineral systems. A total of 256 metrological splits have been prepared from each of these seven materials; these aliquots will be made available to the global geochemical community.

Interpreting siliciclastic sedimentation in the upper Paleozoic Mulargia-Escalaplano Basin (Sardinia, Italy): influence of tectonics on provenance

Late to post-Variscan molassic basins of Late Pennsylvanian-Permian age are exposed in Sardinia (Italy). Here, the compositional and stratigraphic evolution of the Mulargia-Escalaplano sedimentary basin (central Sardinia) has been investigated to highlight how the tectono-magmatic processes have influenced the sedimentation. Ruditic and arenitic samples were collected along well-characterized stratigraphic sections to provide a new insight into the impact of the tectono-magmatic processes on siliciclastic sedimentation. As a result, the conglomerates are mainly clast-supported, petromictic, and thus immature, with no defined maturity trend upwards. Nevertheless, pebble composition changes in times from Variscan basement pebble-rich to volcanic rock-rich, as a consequence of the basin widening and the dismantling and reworking of the coeval volcanic activity. The sandstone composition clearly changes from quartzolithic to feldspatholithic upwards, as a response to the same change of feeding and reworking of the volcanic rocks. Occasionally, interbedded quartzolithic arenites suggest exceptional floods carrying debris from the far borders of the basin. Also, the immature sandstone composition has been interpreted as being controlled by a continuous supply of fresh debris and to a rapid burial rate. In addition, the disappearance of metaradiolarite (lydite AA) Paleozoic grains in the sandstone mineral suite could represent a distinctive marker of a progressive unroofing of the Variscan chain and a clastic supply from deeper tectonic units.

Recent Trends in Cereal- and Legume-Based Protein-Mineral Complexes: Formulation Methods, Toxicity, and Food Applications

Minerals play an important role in maintaining human health as the deficiency of these minerals can lead to serious health issues. To address these deficiencies, current research efforts are actively investigating the utilization of protein-mineral complexes as eco-friendly, non-hazardous, suitable mineral fortifiers, characterized by minimal toxicity, for incorporation into food products. Thus, we reviewed the current challenges in incorporating the cereal-legume protein-inorganic minerals complexes’ structure, binding properties, and toxicity during fortification on human health. Moreover, we further reviewed the development of protein-mineral complexes, characterization, and their food applications. The use of inorganic minerals has been associated with several toxic effects, leading to tissue-level toxicity. Cereal- and legume-based protein-mineral complexes effectively reduced the toxicity, improved bone mineral density, and has antioxidant properties. The characterization techniques provided a better understanding of the binding efficiency of cereal- and legume-based protein-mineral complexes. Overall, understanding the mechanism and binding efficiency underlying protein-mineral complex formation provided a novel insight into the design of therapeutic strategies for mineral-related diseases with minimal toxicity.

Constraining the elemental stoichiometry of early marine life

Abstract The relative proportions of carbon, nitrogen, and phosphorus, commonly referred to as the Redfield ratio (106:16:1), have likely varied dramatically through Earth’s history in response to changes in oceanic redox state and nutrient availability. However, there have been few attempts to track long-term secular patterns in the elemental stoichiometry of marine life. We use a sediment reactive-transport (diagenetic) modeling approach to provide new constraints on the elemental stoichiometry of marine ecosystems during Earth’s early history, by simulating environmental conditions associated with the formation and deposition of suites of Archean sedimentary iron and phosphorus-bearing minerals. Our results suggest that siderite formation in porewaters linked to dissimilatory iron reduction but limited formation of authigenic P phases can only be reproduced when C to P ratios in marine biomass are at least 500 (mol/mol), approximately five times higher than the values that characterize the modern ocean. This constraint indicates that Archean oceans were strongly nutrient-limited.

Fluid Flow, Alteration, and Timing of Cu-Ag Mineralization at the White Pine Sediment-Hosted Copper Deposit, Michigan, USA

Abstract White Pine, located in Michigan’s Upper Peninsula, is an archetypal sediment-hosted stratiform copper deposit. The Midcontinent rift system is one of only seven basins globally that host a giant sediment-hosted stratiform copper deposit. Despite many similarities with other deposits of this type, White Pine displays some important differences, including the late Mesoproterozoic age, a thick basalt sequence, an apparent lack of evaporites, and a lacustrine depositional setting. This study analyzes paleofluid flow related to the formation of White Pine and places a particular emphasis on structural and diagenetic fluid pathways. Most of the ore is located in a 30-m-wide zone spanning the Copper Harbor Formation red beds and the overlying Nonesuch Formation shales. Sedimentation of these units was accompanied by subtle synsedimentary faulting. Premineralization phases include calcite concretions and nodules, illite and hematite grain coatings, isopachous chlorite rims, emplacement of liquid petroleum (now pyrobitumen), and bleaching. Mineralization introduced native copper into the footwall sandstones and a zoned suite of native copper and sulfur-poor copper sulfide minerals across a migrating redox front in the overlying shales where copper minerals nucleated on authigenic and detrital chlorite grains. Postmineralization phases include quartz cement, calcite cement, and calcite veins that partially overlapped inversion of synsedimentary faults. Contrary to previous studies, we identified evidence for only one phase of mineralization. An Re-Os chalcocite age of 1067 ± 11 Ma places mineralization 11 to 17 m.y. after host-rock deposition. Sulfide δ34S values of –14.0 to 29.9‰ suggest an important contribution from sour gas and thermochemical sulfate reduction of seawater. Carbon (δ13C) and oxygen (δ18O) isotope compositions of five calcite generations range from –15.1 to –1.3‰ and 10.4 to 41.3‰, respectively, and record early meteoric pore water displaced by later seawater. White Pine is both a sediment-hosted stratiform copper deposit and a paleo-oil field. Synsedimentary faults controlled the sedimentological character of the upper Copper Harbor Formation, and together these imparted a strong control on fluid flow and later diagenetic processes. Early oxidized meteoric fluids were displaced by liquid petroleum and sour gas, which were in turn succeeded by metal-rich but sulfate-poor oxidized seawater. Burial compaction during deposition of the overlying Freda Formation drove fluids through White Pine due to its situation on a paleotopographic high near the basin margin. Mineralization occurred at ~125°C at depths of ~2.0 km and spanned incipient basin inversion related to the distal effects of Grenvillian orogenesis. The hightenor copper mineral assemblage is the product of an abundant supply of metal from basaltic volcanic detritus in the Copper Harbor Formation and low seawater sulfate concentrations in late Mesoproterozoic oceans. This demonstrates that viable sediment-hosted stratiform copper systems can form when a readily leachable metal source rock is present, even if hypersaline and sulfate-rich brines are not.

Reconstructing formation processes at the Canary Islands indigenous site of Belmaco Cave (La Palma, Spain) through a multiproxy geoarchaeological approach

AbstractThe indigenous populations of La Palma (Canary Islands), who arrived on the island from Northwest Africa ca. 2000 years B.P., were predominantly pastoralists. Yet, many aspects of their subsistence economy such as the procurement, management, and use of wild plant resources remain largely unknown. To explore this, we studied the 600–1100‐year‐old archaeological site of Belmaco Cave, which comprises a stratified sedimentary deposit representative of a fumier. Here, we present a high‐resolution, multiproxy geoarchaeological study combining soil micromorphology, lipid biomarker analysis, X‐ray diffraction, μ‐X‐ray diffraction, μ‐X‐ray fluorescence, Fourier transform infrared spectroscopy, and μ‐Fourier transform infrared spectroscopy, to characterize formation processes and explore plant sources. Recurrent goat/sheep habitation and maintenance activities are represented by interstratified layers of unburned dung, charcoal‐rich sediment, and dung ash. Lipid biomarker data show a herd diet mainly composed of herbaceous plants, which is key to understanding the mobility of indigenous shepherds. Our results also revealed an unusual suite of authigenic minerals including hazenite, aragonite, and sylvite, possibly formed through diagenetic processes involving interaction between ash, dung, urine, volcanogenic components, and bacterial activity, coupled with arid and alkaline conditions. Our study shows the potential of a multiproxy approach to a fumier deposit in a volcanogenic sedimentary context.

The Platinum-Group Minerals of the River Ko Watershed, Sisim Placer Zone, Eastern Sayans, Russia, and the Differentiation of Multicomponent Melts

Abstract The textures and chemical compositions (based on the results of over 1000 analyses) of a suite of platinum-group minerals obtained from concentrates collected along the River Ko watershed in the Sisim placer zone, Eastern Sayans, Russia, have been analyzed and described. Detrital grains of Ir–Os alloy, considered to have been derived from the Lysanskiy layered ultrabasic complex, are interpreted to be domains of melt in the interstices of olivine–chromian spinel cumulates. This melt fractionated before crystallization of the alloys; some domains show a core-to-rim enrichment in Ir. The incompatible behavior of lithophile elements, base metals, S, semimetals, and H2O in the melt now represented by the alloy led to the crystallization of a broad range of ore minerals in multicomponent globules of residual melt. In this way, laurite and cuproiridsite developed in the melt and now are in a symplectitic intergrowth with the alloy. A spherule of laurite with a core of anthophyllite-rich amphibole and a mantle of irarsite shows that H2O and lithophile components were also present in the PGE-rich melt. Rhodium-rich pentlandite-related minerals, likely including oberthürite, postdate the crystallization of laurite; these may be Ru-enriched and may contain lamellar grains of torryweiserite or ferrotorryweiserite, both of which may represent exsolution products. These two species, and the related kuvaevite, which locally replace the Rh-rich pentlandite-related minerals, appear to be paragenetically later. The new data provide valuable insight on the evolution of late, multicomponent melts in basic–ultrabasic complexes.

Muscovite 40Ar-39Ar and cassiterite U-Pb dating of the Indosinian Aotou quartz-vein type tin deposit, southern China and its geological significance

The determination of deposit age is fundamental in economic geology, while the result is often disappointing because of the difficulties in selection of suitable minerals. In this study, on the base of detailed field investigation, we successfully combined the muscovite 40Ar-39Ar dating and cassiterite LA-ICP-MS U-Pb dating in the Aotou tin deposit, Jiangxi province, South China. The result of the muscovite 40Ar–39Ar plateau ages (228.7 ± 1.5 Ma) and the cassiterite U-Pb lower intercept ages (227.4 ± 6.9 Ma) are consistent, accurately defined that the Aotou tin deposit was formed during late Indosinian. With the gradual discovery of another Indosinian W-Sn deposit, we have taken this opportunity to discuss the prospecting index of the Indosinian granite by compiling data of relevant plutons. The result reflects that the Indosinian metallogenic plutons are mainly acidic rocks and produced in the form of small rock mass, with index minerals of muscovite and volatile-rich minerals such as tourmaline and fluorite. Geochemically, they show that the higher SiO2 content (71.51–78.14%), A/CNK (1.13–1.66), Rb/Sr (21.94 in average), but lower Nb/Ta (4.03 in average) and ΣREE (85 ppm in average), which could be useful indexes for identifying the metallogenic pluton. Furthermore, the negative correlation between SiO2 and ΣREE, K2O and Na2O can be used as important ore-prospecting indexes, as a result of they indicate the differentiation of ore-bearing hydrothermal fluids.