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The ratio of 18O to 16O in cherts and other chemical sediments has increased by about 15‰ over geological time, but the cause of this increase is debated. Here, we provide a 1D sediment-column model designed to investigate the role of diagenesis, and specifically the heat flow through marine sediments, in setting the chert oxygen isotope ratios. The model simulates the transformation of amorphous silica (opal-A) to crystalline quartz via an intermediate phase by using a silicon mass balance that is driven by the kinetics and thermodynamics of silica phase dissolution and (re)precipitation. The model demonstrates that heat flow through marine sediments influences the rate, and therefore depths, temperatures, and oxygen isotope compositions, at which cherts form. The implication is that because global heat flow from the solid Earth has decreased through geological time, heat flow is an important contributing factor to the long-term trend in chert oxygen isotope composition. The model is provided as a set of Matlab scripts (".m" files) and assorted input datasets provided as standard plain text files. The model is described in full in the manuscript "Chert oxygen isotope ratios are driven by Earth's thermal evolution" by Michael Tatzel, Patrick J. Frings, Marcus Oelze, Daniel Herwartz, Nils K. Lünsdorf, and Michael Wiedenbeck, and in the online Supporting Information associated with the manuscript. Once downloaded and unzipped, the files should be added to the local Matlab search path. The parameters of interest can be changed in the first few lines of 'chertKineticModel.m'. No other files need to be opened or modified. These files have been tested in Matlab R2020a running on Mac OS X 12.2.1 and in Matlab R2022b on Mac OS X 12.6.1.

The melting relations of the CaCO3 MgCO3 system are investigated and trace element partition coefficient of Li, Na, K, Mn, Fe, Sr, Ba, Pb, Nb, Y and rare earth elements (REEs) between carbonates (Mg-calcite, Ca-magnesite) and dolomitic melt are established from high pressure (6 and 9 GPa) and temperature (1300 1800 ℃) experiments utilizing a rocking multi anvil press. We show that Ca Mg carbonates are stable within the subducting slab beyond ~300 km (9 GPa) but will (partial) melt beneath mid ocean ridges and in upwelling plumes. In contrast to previous studies, we report incongruent melting of carbonates producing a carbonate melt and periclase between 4 and 9 GPa. Partial melting of carbonates produces dolomitic melts whereby the trace element signature largely depends on the Ca/Mg-ratio of the bulk system. For instance, REE will be fractionated by two orders or magnitude between Ca magnesite and dolomitic melt. In contrast, melting of Ca rich carbonates will not lead to a significant REE fractionation. The here published data set includes all chemical analysis (major and trace elment composition) of run products and starting materials. From this data set we obtained the melting relations and partition coefficients reported in Sieber et al. (2020); Sieber et al. (under review).

We provide geochemical data for three sites that define a gradient of erosion rates – an “erodosequence”. These sites are the Swiss Central Alps, a rapidly-eroding post-glacial mountain belt; the Southern Sierra Nevada, USA, eroding at moderate rates; and the slowly-eroding tropical Highlands of central Sri Lanka. Specifically, we provide silicon isotope ratios and germanium/silicon ratios and the major element composition of 1) rock, 2) saprolite, 3) soil, 4) plants, 5) river dissolved loads, 6) the soil and saprolite amorphous silica fraction (accessed with a NaOH leach), and 7) the soil and saprolite clay-size fraction (isolated with a differential settling protocol). These data serve two purposes. First, they allow us to improve understanding of the controls on silicon isotopes and germanium/silicon ratios in the 'Critical Zone'. Specifically, we can quantify the fractionation factors (for silicon isotopes) and the exchange coefficients (for germanium/silicon ratios), for secondary mineral precipitation and for biological uptake. Secondly, we can use mass-balance approaches to quantify the partitioning of silicon - a nutrient, and a major rock-forming element - among secondary minerals, plant material, and solutes. All samples are assigned with International Geo Sample Numbers (IGSN), a globally unique and persistent Identifier for physical samples. The IGSNs are provided in the data tables and link to a comprehensive sample description. This dataset consists of five tables: S1. Analyses of soil, saprolite, and rock from the Swiss Alps study site S2. Analyses of soil, saprolite, and rock from the Sierra Nevada study site S3. Analyses of soil, saprolite, and rock from the Sri Lanka study site S4. Analyses of stream water from the Swiss Alps, Sierra Nevada, and Sri Lanka study sites S5. Analyses of plant material from the Swiss Alps, Sierra Nevada, and Sri Lanka study sites

Situated in the western Erzgebirge metallogenetic province (Vogtland, Germany) the Eichigt prospect is associated with several hydrothermal quartz veins that are exposed at surface. Bulk-rock geochemical assays of colloform Fe- and Mn-oxide aggregates associated with these veins yield high concentrations of Li (0.6-4.1 kg/t), Co (0.6-14.7kg/t) and Ni (0.2-2.8 kg/t), as well as significant quantities of Mn, Cu and light rare earth elements, a very unusual metal tenor closely resembling the mixture of raw materials needed for Li-ion battery production. This study reports the results of a first detailed investigation of this rather unique polymetallic mineralization style, including detailed petrographic and mineralogical studies complemented by bulk rock geochemistry, electron microprobe analyses and laser-ablation inductively-coupled massspectrometry. The mineralized material comprises of an oxide assemblage of goethite and hematite, hollandite and lithiophorite that together cement angular fragments of vein quartz. Lithiophorite is the predominant host of Li (3.6-11.1 kg/t), Co (2.5-54.5 kg/t) and Ni (0.2-8.9 kg/t); Cu is contained in similar amounts in hollandite and lithiophorite whereas LREE are hosted mostly in microcrystalline rhabdophane and florencite finely intergrown with the Mn oxyhydroxides. 40Ar/39Ar ages (~40-34 Ma) of manganomelane link the polymetallic oxyhydroxide mineralization to geothermal activity associated with Cenozoic opening of the Eger rift system. A low temperature hydrothermal overprint of pre-existing base metal sulfide-quartz mineralization on fault structures that were reactivated during continental rifting is thus identified as the most likely origin of the polymetallic oxyhydroxide mineralization at Eichigt. A mixture of metal remobilization from precursor metal sulfide mineralization and/or leaching of crustal rocks may have given rise to the unusual metal tenor.

Global epidemiological studies reported a shift from maternal/infectious communicable diseases to chronic non-communicable diseases and a major part is attributable to atherosclerosis and metabolic disorders. Accordingly, ischemic heart disease was identified as a leading risk factor for global mortality and morbidity with a prevalence of 128 million people. Almost 9 million premature deaths can be attributed to ischemic heart disease and subsequent acute myocardial infarction and heart failure, also representing a substantial socioeconomic burden. As evidenced by typical oxidative stress markers such as lipid peroxidation products or oxidized DNA/RNA bases, the formation of reactive oxygen species by various sources (NADPH oxidases, xanthine oxidase and mitochondrial resperatory chain) plays a central role for the severity of ischemia/reperfusion damage. The underlying mechanisms comprise direct oxidative damage but also adverse redox-regulation of kinase and calcium signaling, inflammation and cardiac remodeling among others. These processes and the role of reactive oxygen species are discussed in the present review. We also present and discuss potential targets for redox-based therapies that are either already established in the clinics (e.g. guanylyl cyclase activators and stimulators) or at least successfully tested in preclinical models of myocardial infarction and heart failure (mitochondria-targeted antioxidants). However, reactive oxygen species have not only detrimental effects but are also involved in essential cellular signaling and may even act protective as seen by ischemic pre- and post-conditioning or eustress – which makes redox therapy quite challenging. © 2020 Elsevier Inc.

We provide geochemical background data on the partitioning and cycling of elements between rock, saprolite, soil, plants, and river dissolved and solid loads from at three sites along a global transect of mountain landscapes that differ in erosion rates – an “erodosequence”. These sites are the Swiss Central Alps, a rapidly-eroding post-glacial mountain belt; the Southern Sierra Nevada, USA, eroding at moderate rates; and the slowly-eroding tropical Highlands of Sri Lanka. The backbone of this analysis is an extensive data set of rock, saprolite, soil, water, and plant geochemical data. This set of elemental concentrations is converted into process rates by using regolith production and weathering rates from cosmogenic nuclides, and estimates of biomass growth. Combined, they allow us to derive elemental fluxes through regolith and vegetation. The main findings are: 1) the rates of weathering are set locally in regolith, and not by the rate at which entire landscapes erode; 2) the degree of weathering is mainly controlled by regolith thickness. This results in supply-limited weathering in Sri Lanka where weathering runs to completion, and kinetically-limited weathering in the Alps and Sierra Nevada where soluble primary minerals persist; 3) these weathering characteristics are reflected in the sites’ ecosystem processes, namely in that nutritive elements are intensely recycled in the supply-limited setting, and directly taken up from soil and rock in the kinetically settings; 4) contrary to common paradigms, the weathering rates are not controlled by biomass growth; 5) at all sites we find a deficit in river solute export when compared to solute production in regolith, the extent of which differs between elements but not between erosion rates. Plant uptake followed by litter erosion might explain this deficit for biologically utilized elements of high solubility, and rare, high-discharge flushing events for colloidal-bound elements of low solubility. Our data and the new metrics have begun to serve for calibrating metal isotope systems in the weathering zone, the isotope ratios of which depend on the flux partitioning between the compartments of the Critical Zone. We demonstrate this application in several isotope geochemical companion papers with associated datasets from the same samples. All samples are assigned with International Geo Sample Numbers (IGSN), a globally unique and persistent Identifier for physical samples. The IGSNs are provided in the data tables and link to a comprehensive sample description in the internet.

Situated in the western Erzgebirge metallogenetic province (Vogtland, Germany), the Eichigt prospect is associated with several quartz-Mn-Fe-oxyhydroxide veins that are exposed at surface. Bulk-rock geochemical assays of vein material yield high concentrations of Li (0.6–4.1 kg/t), Co (0.6–14.7 kg/t), and Ni (0.2–2.8 kg/t), as well as signifcant quantities of Mn, Cu, and light rare earth elements, a very unusual metal tenor closely resembling the mixture of raw materials needed for Li-ion battery production. This study reports on the results of a frst detailed investigation of this rather unique polymetallic mineralization style, including detailed petrographic and mineralogical studies complemented by bulk rock geochemistry, electron microprobe analyses, and laser ablation inductively coupled mass spectrometry. The mineralized material comprises an oxide assemblage of goethite hematite, hollandite, and lithiophorite that together cement angular fragments of vein quartz. Lithiophorite is the predominant host of Li (3.6–11.1 kg/t), Co (2.5–54.5 kg/t), and Ni (0.2–8.9 kg/t); Cu is contained in similar amounts in hollandite and lithiophorite whereas light rare earth elements (LREE) are mainly hosted in microcrystalline rhabdophane and forencite, which are fnely intergrown with the Mn-Fe-oxyhydroxides. 40Ar/39Ar ages (~40–34 Ma) of coronadite group minerals coincide with tectonic activity related to the Cenozoic Eger Graben rifting. A low-temperature hydrothermal overprint of pre-existing base metal sulfde-quartz mineralization on fault structures that were reactivated during continental rifting is proposed as the most likely origin of the polymetallic oxyhydroxide mineralization at Eichigt. However, tectonically enhanced deep-reaching fracture-controlled supergene weathering cannot be completely ruled out as the origin of the mineralization.

Deportment data is essential for the planning of mining and minerals processing operations. This need is particularly tangible for deposits of noble metals, such as gold and silver. Therefore, the current paucity of published gold and silver deportment data for individual ore deposits and districts – and the concomitant lack of understanding how this relates to salient geological and mineralogical features of these deposits – is surprising. In the present study, we apply a combination of bulk geochemistry, laser ablation-inductively coupled plasma-mass spectrometry, electron microprobe analysis, and mineral liberation analysis to gold- and silver-rich samples from the epithermal Freiberg Ag-Pb-Zn district, to investigate variability in gold and silver deportments, as well as the corresponding geological/mineralogical controls. The results show that the main carriers of gold are electrum and arsenopyrite, whereas silver is mostly hosted by Ag-sulfosalts (pyrargyrite, miargyrite, polybasite) and fahlore (freibergite). Deportments vary greatly between samples. These variations can be related to the relative abundances of different minerals within the samples, which in turn reflect their spatio-temporal position within the district. Comparisons with other epithermal Ag-Pb-Zn districts similar to Freiberg indicate that the results presented here are of general significance.

International audience; Understandingdegassing processesof magmatic systemsis crucial for the prediction and risk assessmentof volcanic eruptions.Lithium and boron are light elements,moderately incompatibleto silicate minerals,and both have two stable isotopes. Over the past two decades, Li and B have been widely used to detect subduction-related processes, but they may also be considered as volcanic geospeedometers.During magmatic decompression, thesolubility of volatile phases(mainly H2O and CO2)decreases, causing volatile exsolution and bubble formation.As Li and B are fluid-mobile elements, their abundance and distribution in the melt will be strongly affected by magma degassing. Therefore, we have measured the concentrationsof the two elements in erupted matrix glassesand olivine-bearing melt inclusionsof several natural samples;namelythe 1944 and AD 79 eruptions of Mt. Vesuvius (Italy), the 2007 eruption and other historic lavas from Piton de la Fournaise(La Réunion), the Minoaneruption of Santorini (Greece),andthe 1902 eruption of Mt.Pelée (Martinique). Major elements have beenmeasured by electron microprobe, while Li and B elemental concentrations were analyzed by LA-ICP-MS.Natural melt inclusions showverylowLi and B values(average contents are 12.3ppm and 7.6ppm, respectively). While the naturally erupted and degassed matrix glasseshave Li and B contents in the range of 20-60ppm. Additionally, sets of decompression and diffusion-couple experimentson synthetic water-bearing rhyolitic glasses are currently being performed inan internally heated pressure vesselat elevated pressures and temperatures. This will allow us to comparethe results of our natural samplesto the experimental data, findingpotential correlationsbetween the decompression rate and the Li and B elemental and isotopic behaviour.Preliminary results of element mapping and profile measurements emphasize the fluid mobilty of Li and B during experimental magma degassing.

The precipitation of As-rich pyrite (“fool’s gold”) can scavenge gold from hydrothermal fluids to form giant ore deposits., The giant Carlin-type Au deposits (Nevada, USA) contain gold hosted in arsenic-rich iron sulfide (pyrite), but the processes controlling the sequestration of Au in these hydrothermal systems are poorly understood. Here, we present an experimental study investigating the distribution of Au and As between hydrothermal fluid and pyrite under conditions similar to those found in Carlin-type Au deposits. We find that Au from the fluid strongly partitions into a newly formed pyrite depending on the As concentration and that the coupled partitioning behavior of these two trace elements is key for Au precipitation. On the basis of our experimentally derived partition coefficients, we developed a mass balance model that shows that simple partitioning (and the underlying process of adsorption) is the major depositional process in these systems. Our findings help to explain why pyrite in Carlin-type gold deposits can scavenge Au from hydrothermal fluids so efficiently to form giant deposits.

The trace element distribution in samples from eight VMS deposits which have experienced varying metamorphic grades were investigated by LA-ICP-MS spot analyses and mapping. Gold and the PGE in pyrite can be observed in samples from varying metamorphic grades. They do not show any systematic variation depending on metamorphic pressure or temperature and their presence in the samples indicate that no melt migration has occurred. Samples from deposits at amphibolite metamorphism show a homogeneous distribution of Se, Sb, and Te, while Ag, Rb, Sr, Mo,and Bi are enriched in bornite compared to sphalerite and pyrite. At greenschist metamorphic grade, Se and Sb are heterogeneously distributed among the different sulfide phases with Se being most enriched in pyrrhotite and Sb in chalcopyrite. Tellurium shows a homogeneous distribution between sulfide phases. Some other elements are as well enriched in chalcopyrite compared to pyrite and pyrrhotite, including V, Cr, Mn, Ni, Ga, Ge, Mo, Ag, Cd, In, Sn, and W. Cadmium, In, and Mn are even more enriched in sphalerite compared to chalcopyrite in weakly metamorphosed VMS. Indium concentrations in sphalerite are up to 0.1 wt%. Indium, Mn, and Cd in sphalerite, and Bi in galena are homogenously distributed in trace element maps in two samples from greenschist and epidote-amphibolite facies metamorphosed deposits. Cobalt is observed to occur only at the rim of pyrite grains in the sample from the greenschist facies metamorphosed deposit, while in the sample which experienced higher metamorphic P and T, Co occurs only in the centre of pyrite grains. Germanium and W show a homogeneous distribution in pyrite. Tin is homogeneously distributed in chalcopyrite.

The authors regret that they have to correct the acknowledgement of the above mentioned publication as follows: This article/publication is based upon work from COST Action BM1203 (EU-ROS), supported by COST (European Cooperation in Science and Technology) which is funded by the Horizon 2020 Framework Programme of the European Union. COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. For further information see www.cost.eu. The authors would like to apologise for any inconvenience caused. © 2017 The Author(s)

During the weathering of minerals and rocks elements are released into the ambient solution. The isotope ratios potentially trace the way Si is released from Si-bearing solids into soil and (diagenetic) interstitial solutions. They also trace how silica is precipitated into secondary solids from these solutions. In particular, the partitioning of Si isotopes in the presence of Al has not been explored in detail under controlled laboratory conditions and the related Si isotope fractionation factors need to be determined. The determination of these fractionation factors is so important as in virtually all Earth surface reactions, Si being released from primary silicates is accompanied by variable amounts of Al. Crucial in the understanding of Si isotope fractionation in the presence of Al are two processes: 1.) Si isotope fractionation during adsorption onto Al precipitates and 2.) Si isotope fractionation during Si precipitation from solutions in the presence of variable Al concentrations. Si precipitation experiments reveal that during cyclic freeze-thaw of dissolved Si-containing solutions, Si is removed from the solution. In the absence of appreciable amounts of Al this removal is not accompanied by a fractionation of Si isotopes. In contrast if Al is present in these solutions at high concentrations (here 1 mmol/l), Si removal is faster and accompanied by strong Si isotope fractionation favoring the light isotopes in the solids. The conducted adsorption experiments presented reveal that adsorption of monomeric silicic acid onto gibbsite is accompanied by a significant kinetic Si isotope fractionation and that light Si isotopes are preferentially adsorbed. The calculated Si isotope fractionation factors are dependent on the initial Si concentration. High initial Si concentrations result in a strong kinetic Si isotope fractionation during adsorption. This initial kinetic signature begins to re-equilibrate only after ca. two months. Having established the principle fractionation factors in these experiments also the Si isotopic composition of natural samples have been explored, to investigate the dependence of Si isotope fractionation related to soil processes under different kinetic weathering regimes. The Si isotope measurements of the amorphous and clay fraction extracted from soils and saprolites reveal that a strong relationship between the Si isotopic composition of these pools and the regolith residence time of the three different weathering regimes exists. An increase in regolith residence time leads to lower 30Si/28Si ratios for secondary silicates formed in different weathering regimes. An isotope mass balance model reveal that the proportion of particulate export flux increases over the dissolved import Si flux according to the decrease in regolith residence time. This change is mirrored in the 30Si/28Si ratios of secondary precipitates., Während der chemischen Verwitterung von gesteinsbildenden Mineralen und anstehendem Festgestein werden Elemente in die umgebene Bodenlösung abgegeben. Verhältnisse der stabilen Si Isotope zeigen dabei den möglichen Pfad von Si von der Freisetzung bei der Verwitterung von primären Mineralen und anstehenden Festgestein bis zum anschließenden Einbau in sekundäre Minerale auf. Die Bestimmung von Si Isotopenfraktionierungsfaktoren von Reaktionen zwischen Al und Si sind daher von grundlegender Bedeutung, da es sich mit hoher Wahrscheinlichkeit um die ersten Reaktionen nach der Freisetzung der beiden Elemente handelt. Bei Reaktionen von Al und Si nehmen zwei wesentliche Prozesse eine führende Rolle ein: 1.) Si Isotopenfraktionierung bei der Adsorption von Si an Al Ausfällungen und 2.) Si Isotopenfraktionierung bei der Ausfällung von Si aus wässrigen Lösungen in An- und Abwesenheit von Aluminium. Die durchgeführten Si Ausfällungsexperimete zeigen, dass es beim zyklischen Gefrieren und Auftauen von Si enthaltenen Lösungen zur Ausfällung von Si kommt. Wenn es sich dabei um reine Si Lösungen (ohne Zugabe von Al) handelt, dann findet bei der Ausfällung keine Si Isotopenfraktionierung statt. Im Gegensatz zu den Al freien Si Ausfällungsexperimenten ist die Si Ausfällung bei der Zugabe von Al (hier 1 mmol/l) schneller und geht mit einer Si Isotopenfraktionierung einher, bei der bevorzugt leichtes Si in die Ausfällungen eingebaut wird. Die durchgeführten Si Adsorptionsexperimente zeigen, dass es bei der Adsorption von Monokieselsäure an Gibbsit zu einer signifikanten Si Isotopenfraktionierung kommt, wobei die leichten Si Isotope bevorzugt adsorbiert werden. Die bestimmten Si Isotopenfraktionierungsfaktoren sind stark abhängig von der initialen Si Konzentration. Die initiale kinetische Si Isotopensignatur zeigt Anzeichen einer Reequilibrierung erst nach ca. zwei Monaten Versuchsdauer. Weiterhin wurde die Si Isotopenzusammensetzung von natürlichen Proben und der Zusammenhang zwischen der Si Isotopensignatur und Bodenbildungsprozessen in unterschiedlichen Verwitterungsregimen untersucht. Resultate der Si Isotopenmessungen der amorphen Si Fraktion und der Tonfraktion von Böden und Saprolit zeigen, dass es einen starken Zusammenhang zwischen der Si Isotopenzusammensetzung dieser Phasen und der Verweilzeit im Regolith in den unterschiedlichen Verwitterungsregimen gibt. Längere Regolith--Verweilzeiten führen zu niedrigeren 30Si/28Si Verhältnissen in den sekundär gebildeten Si Ausfällungen. Ein Isotopen--Massenbilanzmodel zeigt, dass das Verhältnis von partikulären Export von Si enthalten in sekundären Phasen zu dem Import von gelösten Si in die Verwitterungszone ansteigt, wenn die Regolith--Verweilzeit abnimmt. Dieser Wechsel wird in den 30Si/28Si Verhältnissen der sekundär gebildeten Si Ausfällungen abgebildet.

International audience; In the Wadi Haymiliyah of the Oman ophiolite (Haylayn block), discordant wehrlite bodies ranging in size from tens to hundreds of meters intrude the lower crust at different levels. We combined investigations on natural wehrlites from the Wadi Haymiliyah section with an experimental study on the phase relations in a wehrlitic system in order to constrain the petrogenesis of the crustal wehrlites of the Oman ophiolite. Secondary ion mass spectrometry analyses of clinopyroxenes from different wehrlite bodies imply that the clinopyroxenes were crystallized from tholeiitic, mid-ocean ridge (MORB)-type melts. The presence of primary magmatic amphiboles in some wehrlites suggests a formation under hydrous conditions. Significantly enhanced Sr-87/Sr-86 isotope ratios of separates from these amphiboles imply that the source of the corresponding magmatic fluids was either seawater or subduction zone-related. The experiments revealed that under wet conditions at relatively low temperatures, a MORB magma has the potential to produce wehrlite in the ocean crust by accumulation of early olivine and clinopyroxene. These show typically high Mg# which is a consequence of the oxidizing effect of the prevailing high aH(2)O. First plagioclases crystallizing after clinopyroxene under wet conditions are high in An content, in contrast to the corresponding dry system. Trace element compositions of clinopyroxenes of those wehrlites from the Moho transition zone are too depleted in HREE to be in equilibrium with present-day MORB, implying a genetic relation to the V2 lavas of the Oman ophiolite, which are interpreted to be the result of fluid-enhanced melting of previously depleted mantle. We present a model on the petrogenesis of the crustal wehrlites in an upper mantle wedge above an initial, shallow subduction zone at the beginning of the intraoceanic thrusting.