Mantle-hosted granitoids (MHG) from the supra-subduction Samail ophiolite in Oman and the United Arab Emirates exhibit diverse compositions, highlighting variations in petrogenesis and source contributions. Previous isotopic data indicate these MHG originated through the interaction of sediment-derived with basaltic melts from an underthrust oceanic plate within the mantle wedge. The sedimentary contribution was attributed to the partial melting of pelitic to siliceous (bio-siliceous) material atop the subducted plate based on elevated zircon delta O-18 values (similar to 14-28 parts per thousand). To further evaluate this hypothesis on Samail MHG petrogenesis and source contribution, we present new and compiled radiogenic (Sr-Nd-Hf-Pb) and stable (O-Li-H) isotopes, along with zircon trace element analyses. The variable Sr and Pb isotopic signature support a mixed origin involving altered mafic and sedimentary sources in the formation of the MHG. Negative whole-rock epsilon Nd, coupled with elevated delta Li-7 in muscovite suggest the involvement of sedimentary sources and particularly those resembling deep-sea ferromanganese-rich sediments. We propose a new model identifying ferromanganese sediments as a potential source given their widespread distribution across the ocean floor, broad range of delta O-18 (up to 29.5 parts per thousand), slightly positive Hf values, seawater-like delta Li-7 signatures (median of similar to 27 parts per thousand), and zircon trace element compositions lacking a signature of monazite co-precipitation, which match the signatures required for the genesis of the Samail MHG. Preservation of oceanic lithosphere in the geological record is limited, and MHG in ophiolites are uncommon. Therefore, the Samail MHG are key examples of crustal materials transported to the mantle, with implications for mantle heterogeneity and arc mantle redox budget.

A combined laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and energy dispersive Xray spectroscopy (EDS) study was used to map 49 elements in four Fe-Mn - Mn precipitates produced from three different genetic processes (hydrogenetic, hydrothermal, and mixed-type hydrogenetic-hydrothermal) in samples obtained from the southern Mariana Arc. Results show Mn-oxide minerals are consistently found to be associated with Ba, Mo, Sb, V, Zn, and the rare earth elements and yttrium (REY), excluding Ce, whereas Fe-oxyhydroxide minerals are primarily associated with Ti, Co, Cr, Cu, Nb, and Pb. Element distributions in Fe-Mn - Mn precipitates from the southern Mariana Arc differ from deposits formed in other environments; notably, there is a decoupling of As and Sb, and redox-sensitive elements are more variable than non-redox-sensitive elements. Samples previously classified as either hydrogenetic or hydrothermal in origin, based on bulk geochemical data, show characteristics of both at higher resolution. Combining high resolution in-situ data with genetic classification discrimination diagrams reveals more ambiguity in metal and metalloid origin than previously thought. Mariana Arc Fe-Mn - Mn precipitates can be separated into two formation sub-types (hydrothermal or mixed hydrothermal/ hydrogenetic) based on textural and compositional differences, e.g., differences in Ce/Ce and Y/Ho values and relative variations in (Zr + Y + Ce) versus (Co + Ni) versus (Mn + Fe). Improved classification and knowledge of how fast-growing hydrothermal Fe-Mn - Mn precipitates form may help us identify a relatively renewable critical metal resource.

At the Grimlock laterite deposit (Northern Territory, Australia), Co and Ni mineralization occurs mainly in the Mn-oxide rich layers of the ferromanganese (Fe-Mn) crust overlying ultramafic bedrock. Groundwater-associated Fe-Mn crusts consist of mineral (e.g. Mn-oxide, Fe-oxyhydroxide and silicate) groups suitable for studying triple oxygen isotopes and present unique interpretative challenges (e.g. small Mn-oxide fractions relative to Fe-Mn precipitates from other formation environments and extensive weathering). We evaluate triple oxygen isotopes within the context of changes to properties (i.e. mineralogy, major and trace element geochemistry, and degree of weathering) of a lateritic profile. We use pre-existing mineral-water fractionation factors, meteoric water δ 18 O and temperature data to calculate δ 18 O values of fully altered mineralogical endmembers, then, using mass balance, discuss scenarios to elucidate measured whole-rock δ 18 O values. The δ ′ 18 O (′ denotes linearized notation) and Δ ′ 17 O of near-surface samples (0–8 m) are generally lower (mean of 8.892‰) and higher (mean of −0.141‰), respectively, than the δ ′ 18 O (mean of 12.767‰) and Δ ′ 17 O (mean of −0.176‰) of samples from greater depths (19–22 m). At 16–17 m depth, δ ′ 18 O and Δ ′ 17 O are relatively high (means of 17.509 and −0.118‰, respectively). The measured whole-rock δ 18 O values are explainable by substituting lower δ ′ 18 O values for the Mn-oxide and Fe-oxyhydroxide fractions, and higher δ ′ 18 O values for the aluminosilicate fraction, changes coinciding with greater alteration. These results suggest that mineral weathering is primarily responsible for observed variations in the triple oxygen isotopes of groundwater-associated Fe-Mn crusts, rather than variation in the initial source of oxygen incorporated into Mn-oxide. Supplementary material: Grimlock sample photographs, XRD patterns and supplementary figures and tables are available at https://doi.org/10.6084/m9.figshare.c.7071907

Few studies have focused on the application of the Tl isotopic system for geochemical exploration. We report ε 205 Tl values of rock samples from the TL Deposit, British Columbia, Canada – a sediment-hosted massive sulfide (SHMS) deposit with characteristics of a Broken Hill-type deposit – and investigate relationships with major and trace element geochemistry. Maps generated using Tl isotope and trace element data indicate that ε 205 Tl values can potentially be used to fingerprint ore mineralization at the TL Deposit. The sources of Tl and other metals (Ag, Pb, Zn) are assessed using Tl isotope data. Measured ε 205 Tl values exhibit positive correlations with Pb, sedimentary exhalative metal index (Zn + 100*Pb + 100*Tl), and the redox proxy, U/Th, and negative correlations with Be, Cd, Ce, La, Ni and Th. Individual lithologies have distinct Tl isotopic compositions. Metal-rich heavily altered samples have relatively high ε 205 Tl values (−5.0 to −2.5 ε -units) reflecting the euxinic conditions of the global Paleoproterozoic ocean and hydrothermal influence. Samples with lower ε 205 Tl values (−15 to −7.6 ε -units) reflect a combination of their mineralogy (phyllosilicate minerals such as biotite and clinochlore), Tl from sediments reflecting the Tl isotopic composition of modern seawater, and possible low-temperature alteration processes. Samples with high Pb and Ag contents have high ε 205 Tl values, indicating a hydrothermal origin of these metals, whereas Zn is highest in samples with low ε 205 Tl values, indicating a low-temperature or sedimentary origin. Thallium isotopes, paired with conventional geochemical data, show promise as a useful tool for exploration of SHMS deposits with Broken Hill-type characteristics. Supplementary material: Major, minor and trace element contents of samples and reference materials, blank values, correlation coefficient values, and XRD patterns are available at https://doi.org/10.6084/m9.figshare.c.6370671 Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits

Sveite, KAl7(NO3)4(OH)16Cl2·8H2O, is a rare, water-soluble mineral with an undetermined atomic structure. New major, minor, and trace element data for sveite from three localities (Cerro Autana Cave, Venezuela; San Joaquin Valley, USA; Ponta Grossa, Brazil) are reported using modern analytical techniques (inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and ion chromatography). Powder X-ray diffraction, micro-X-ray diffraction, and scanning electron microscopy-energy dispersive X-ray spectroscopy are used to characterize the identity of residues following digestions of different strengths, i.e., ultrapure H2O, 2%, 20%, and concentrated HCl acid. Sveite from Venezuela has approximately 3 wt.% more K and 5 wt.% less Al than reported by Martini (1980), and that from California has 20 wt.% less Al than was reported by Graham et al. (1988). Sveite from California has higher N (∼8 wt.%) and lower K (4.5 wt.%), Al (∼12 wt.%), and Cl (∼0.5 wt.%) contents compared to that from Venezuela (∼6 wt.% N, ∼7 wt.% K, ∼15 wt.% Al, and ∼10 wt.% Cl contents). Sveite from Brazil has extremely low K (<0.1 wt.%) and high N (∼24 wt.%) contents with respect to those from the other localities. To inhibit formation of aluminum chloride on dissolution, which can subsequently impact results from geochemical analyses, it is recommended that ultrapure H2O be used to digest sveite. Geochemical and spectroscopic evidence suggests that sveite from different localities may represent distinct mineral species within a potentially larger group of sveite-type minerals. A revised chemical formula for sveite from Venezuela is K2.73Al7.97(NO3)6O8.27Cl4.1·35H2O, Z = 2, leading to a more general formula of (K3−x□x) Al8(NO3)6O8Cl4·nH2O, Z = 2. The lack of K and Cl in material from other localities that shows similar powder diffraction patterns would require a more general formula.

Interactions between a cyanide leach used for Au extraction and cinnabar-bearing gossan tailings at the Murray Brook mine have led to the development of an Hg-enriched contaminated groundwater plume that discharges to the nearby Gossan Creek. Naturally occurring cinnabar in the area poses a challenge in distinguishing mining-related contamination from background Hg concentrations. Surface water data from throughout the Bathurst Mining Camp was used to establish interelement relationships compared to pH and the spatial distributions of Hg, SO42−, Cl, Cu, NO3−, Zn, Pb, and Ca/HCO3− values. Statistical significance of anomalous measurements was evaluated to assess geogenic versus anthropogenic contributions of mining associated elements. Watershed analysis indicated that the Murray Brook tailings facility may sit on a basinal divide with potential for tailings leachate-impacted groundwater and surface water migration toward the northeast as well as northwest toward Gossan Creek. Elevated NO3− was detected in two streams south-west of Gossan Creek alongside greater than normal Hg concentrations. Other locations in the study area away from the Murray Brook area show little geochemical evidence for impact of mining on surface waters despite Hg concentrations as high as 0.019 µg L-1. Points with geogenic Hg concentration on the order of 0.01 µg L-1 were observed throughout the study area, particularly in the Upsalquitch River tributaries south-west of Gossan Creek and in the surface waterbodies west of the Restigouche deposit, indicating weathering of cinnabar-bearing gossan.

Ferromanganese precipitates - crusts, nodules, and hydrothermal deposits – typically exhibit negative Δ'17O values. These deviations are thought to reflect partial incorporation of dissolved atmospheric O2, a component with strongly negative Δ'17O values, seawater oxygen, and deep sea O2 into Mn-oxide minerals, in combination with the other major mineralogical endmember components (Fe-oxyhydroxide and silicate minerals), and kinetic processes such as oxidation at mineral surfaces and biological respiration. Our understanding of the triple oxygen isotope systematics of these materials are limited, however; in the current body of literature, triple oxygen isotope data has only been generated for marine hydrogenetic (i.e., metals accrete directly from seawater) Fe-Mn crusts and Mn nodules. This study evaluates the underlying chemical and environmental factors contributing to the bulk triple oxygen isotopic composition of Fe-Mn precipitates of different genetic types (i.e., hydrothermal, hydrogenetic, mixed-type) from a variety of formation environments (e.g., volcanic arc, pull-apart basin, hotspot, freshwater lake). To improve our understanding of the triple oxygen isotope systematics of natural Fe-Mn precipitates and better constrain the endmember components, we isolate and measure close approximations of the Mn-oxide, Fe-oxyhydroxide, and silicate fractions. Hydrothermal Fe-Mn deposits show greater variation in δ'18O and Δ'17O values (6.0 to 29.6 ‰ and −0.286 to 0.007 ‰, respectively) than hydrogenetic Fe-Mn crusts (5.1 to 11.9 ‰ and −0.200 to −0.086 ‰, respectively). Lacustrine Mn nodule δ'18O and Δ'17O values (5.1 to 8.8 ‰ and −0.230 to −0.090 ‰, respectively) are similar to marine hydrogenetic Fe-Mn crusts, primarily reflecting tropospheric O2. The triple oxygen isotope ratios of nearly pure Mn-oxide samples cluster into distinct groups based on oxygen source, and mass-balance mixing models suggest a significant proportion of incorporated oxygen was photosynthetic in origin. The layered Fe-Mn precipitates in this study show irregular to rhythmic patterns of δ'18O and Δ'17O values depending on formation environment that mostly do not correlate with Mn, Fe, and Si contents. Shale-normalized rare earth element and yttrium (REYSN) patterns and anomalies (CeSN/CeSN*, EuSN/EuSN*, and YSN/HoSN), which can provide insight on formation conditions (e.g., redox, oxygen fugacity, and REY speciation of fluids), are compared with the triple oxygen isotope data. The REYSN anomalies increase from the bottom to the top of the profile of the layered marine sample, suggesting conditions became more oxic over time. Although the triple oxygen isotope ratios correlate with the Eu anomaly in most Fe-Mn precipitates, hydrothermal input can limit their utility as indicators of oxygen fugacity. The triple oxygen isotope ratios of Fe-Mn precipitates reflect complex processes and mixing of multiple sources. Constraining these oxygen sources will assist future studies in interpreting paleoenvironmental conditions (e.g., the saturation state and triple oxygen isotope ratios of dissolved O2 in bottom water) at the time of Fe-Mn precipitate formation.

On June 12, 2004, a meteorite passed through Earth's atmosphere and landed under the television in the living room of a house in Auckland, New Zealand. Textural characteristics, the chemistry of olivine (Fa(23-24)) and orthopyroxene (Fs(20.7)), and the bulk rock triple oxygen isotopes (delta O-17 + 3.1; delta O-18 + 4.2 parts per thousand) from the interior of the completely unweathered (W0) 1.3 kg meteorite, hereafter referred to as Auckland, suggest it to be a strongly metamorphosed fragment from the interior of a low iron ordinary chondrite (L6) parent asteroid. The occurrence of maskelynite but shock fracturing of olivine and pyroxene indicates Auckland experienced extreme shock metamorphism (S5), likely during Ordovician fragmentation of the asteroid parent. The fusion crust consists of three zones: (1) an innermost zone containing narrow Fe-Ni-S-bearing veins that migrated along pre-existing shock fractures in olivine and pyroxene; (2) a middle zone in which the meteorite partially melted to form a silicate glass and immiscible blebs of metal and troilite, and is accompanied by unmelted silicate minerals; and (3) an approximately 0.1 mm wide vesicular-rich outermost layer that largely melted, volatilizing sulfides, before quenching to form glass and olivine. Oxygen isotope values of the bulk rock and/or maskelynite of melted rim and modified substrate are 2-3 parts per thousand greater than the meteorite interior and indicate that up to 19% of terrestrial atmospheric O-2 was incorporated into the fusion crust during the formation. The fusion crust migrated inwards as ablation occurred, enabling melting, migration, and re-precipitation +/- loss of sulfide and metal components, with the prominent glassy rim therefore forming from an already chemically modified zone.

In hydrogeochemical studies, samples are commonly filtered to limit the fraction of analyte that is adsorbed or structurally bound to suspended particles, ensuring that only the dissolved fraction is analysed, and thereby reducing analytical bias during measurement. The standard filter size that has been adopted is 0.45 μ m; however, ultrafiltration can be used to remove colloidal particles two orders of magnitude smaller. In the following, we investigate the effect that standard filtration (0.45 μ m) and ultrafiltration (0.004 μ m) have on the hydrogeochemistry of groundwaters from a volcanogenic massive sulfide (VMS) deposit at the Bathurst Mining Camp, New Brunswick, Canada. Groundwater samples were collected from six monitoring wells at the Nigadoo Mine tailings facility, and major and trace geochemistry were determined using a combination of inductively coupled plasma optical emission spectrometry, inductively coupled plasma mass spectrometry and ion chromatography. Waters at the Nigadoo deposit are generally enriched in Ca and SO 4 , relative to other major cations and anions. Some element contents – including those associated with VMS deposits – differ depending on the filtration technique used (e.g. As, Fe, Pb, rare earth elements and yttrium (REY)), some are equally affected by both techniques (e.g. Cu, Ni, Zn), and some are unaffected by filtration (e.g. Ba, Ca, Mn, Cl − ). Shale-normalized REY anomalies (Ce SN /Ce SN *, Eu SN /Eu SN * and Y SN /Ho SN ) and overall patterns can differ greatly (e.g. changing the sign of the anomaly) depending on the filtration technique used. We observe previously undocumented and, at this time, unexplainable fractionation of Ho and Yb (non-redox sensitive REY, unaffected by the tetrad effect) in unfiltered waters from the Nigadoo deposit. Differences in groundwater geochemistry induced by filtration technique can result in false positive and negative anomalies during environmental and exploration projects and must therefore be carefully considered. At the Nigadoo site, oxidation of sulfide minerals can occur, resulting in the formation of relatively unstable oxide minerals. Away from the tailings, where carbonate minerals are scarce and can no longer act as a pH buffer, the unstable oxide minerals break down and release metals and metalloids into the surrounding environment. The filtration methods used in this study can provide insight into where the specific metals and metalloids are hosted and how they are likely to behave under different redox conditions. Because VMS deposit pathfinder elements are enriched in unfiltered water, and differ by degree of filtration, geochemical analysis of the filtride material may also make an effective exploration tool. Thematic collection: This article is part of the Hydrochemistry related to exploration and environmental issues collection available at: https://www.lyellcollection.org/cc/hydrochemistry-related-to-exploration-and-environmental-issues

The Mariana intraoceanic volcanic arc system in the western Pacific Ocean hosts abundant ferromanganese (Fe-Mn) precipitates. A suite (n = 22) of Fe-Mn precipitates were collected from the southern portion of the arc and their mineralogies and chemical compositions were determined. These results were used to decipher their genetic assemblage, assess their potential as a source of trace metals, and place them into context with respect to Fe-Mn precipitates sampled at higher latitudes in the Mariana arc and from other locations, globally. Minerals identified include vernadite, birnessite, 10 angstrom manganate, manganite, hematite, goethite, maghemite, calcite, rhodochrosite, quartz, phillipsite, various feldspar, pyroxene, and clay minerals. Element discrimination diagrams indicate that the samples are predominantly of hydrothermal and hydrogenetic-hydrothermal (i.e., mixed) origin, with most reflecting some influence of both. Rare earth element and Y (REY) profiles are distinguished by negative Ce and Y anomalies and positive Eu anomalies. Together, the samples form a continuum from the hydrogenetic to hydrothermal endmembers. Samples with the largest hydrogenetic component are friable with branching oxide/oxyhydroxide growth structures, contain mostly vernadite, and have the greatest concentrations of most metals (including the REY elements). Hydrothermal input produces denser, cemented deposits that contain more 10 A and 7 A manganate minerals and lower minor-metal contents. Calculated growth rates range from 6 mm to >190 m Ma(-1). Average metal contents of Fe-Mn precipitates from the southern Mariana arc are low relative to hydrogenetic Fe-Mn crusts and hydrothermal Fe-Mn deposits from the northern Mariana arc and elsewhere, globally, and are therefore unlikely to be viable exploration targets.

Manganese nodules are a type of ferromanganese chemical precipitate containing a plethora of economically important metals increasingly being used in the high- and green-technology sectors. By measuring oxygen isotope ratios in these materials, we can increase our understanding of how they form, and constrain which metals are likely to be present in them. There is a lack of suitable reference materials for use in oxygen isotopic studies of samples dominated by Mn oxide minerals (i.e., Mn nodules and crusts) and, therefore, a need for their development. The samples NOD-A-1 and NOD-P-1 (United States Geological Survey), Mn nodules from the Atlantic and Pacific oceans, respectively, provide the best opportunity for such a reference material but their application has been hampered by their incomplete mineralogical characterization and lack of consensus on how to pre-treat (if at all) these type of samples for delta O-18 analysis. We have performed a detailed mineralogical study using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), powder X-ray diffraction (PXRD), and Raman spectroscopy on these reference materials. In sample NOD-A-1 todorokite, goethite and/or hematite, Mg-calcite, phillipsite or chabazite, quartz and barite were identified. The minerals todorokite, birnessite, asbolane, vernadite, goethite, pyrochroite, quartz, phillipsite or chabazite, anorthite, kaolinite and barite were identified in NOD-P-1. We conducted experiments to assess the effect on delta O-18 and mineralogy resulting from acidification with hydrochloric acid (HCl), pre-fluorination with bromine pentafluoride (BrF5) at ambient temperature, or both acidification and pre-fluorination treatments. Results from samples given both treatments were deemed most meaningful to the study of Mn crusts and nodules, and therefore nodule research in general, by providing delta O-18 values representative of the relatively pure oxide-silicate fraction only. We report a delta O-18 value of 11.0 +/- 1.0 parts per thousand for the oxide-silicate fraction of NOD-A-1, and a value of 11.1 +/- 0.7 parts per thousand for the same fraction in NOD-P-1, with results showing a delta O-18 shift of up to 10.3 parts per thousand, as a function of nodule and the pre-treatment used. The delta O-18 values of samples given both treatments converge and are substantially O-18-depleted relative to that of corresponding untreated material, which was found to contain various O-18-enriched phases such as carbonate minerals and non-stoichiometric water. Based on our results, we recommend that for all future analyses of Mn nodules and crusts, the samples receive both treatments to ensure accurate and consistent results.