Understanding the patterns of marine microbial diversity (Bacteria + Archaea) is essential, as variations in their alpha- and beta-diversities can affect ecological processes. Investigations of microbial diversity from global oceanographic expeditions and basin-wide transects show positive correlations between microbial diversity and either temperature or productivity, but these studies rarely captured seasonality, especially in polar regions. Here, using multiannual alpha-diversity data from eight time series in the northern and southern hemispheres, we show that marine microbial community richness and evenness generally correlate more strongly with daylength than with temperature or chlorophyll a (a proxy for photosynthetic biomass). This pattern is observable across time series found in the northern and southern hemispheres regardless of collection method, DNA extraction protocols, targeted 16S rRNA hypervariable region, sequencing technology, or bioinformatics pipeline.

The geochemistry of asteroidal magmas provides fundamental clues to the processes involved in the origin and early evolution of planetary bodies. Although sulfides are important reservoirs for a diverse suite of major and trace elements, it is currently unclear whether the interiors of asteroid Vesta and the Angrite Parent Body were sulfide liquid saturated during petrogenesis of non-cumulate eucrites and volcanic angrites. To assess the potential of sulfide liquid saturation in the interiors of these bodies, high pressure (P) - temperature (T) experiments were used to quantify the sulfur concentrations at sulfide saturation (SCSS) for volcanic angrites and non-cumulate eucrites. The sulfide-silicate partitioning behavior of various trace elements was simultaneously quantified to study their geochemical behavior at sulfide liquid saturation.

The Earth may have formed at very reducing conditions through the accretion of (a) large reduced and differentiated impactor(s). Segregation of Fe-S liquids within these bodies would have left a geochemical mark on the mantles of reduced impactors and on the proto-Earth's mantle. Here, we study the geochemical consequences of highly reduced accretion of the Earth by large impactors. New insights into the partitioning of trace elements between Fe-S liquid and silicate melt at (highly) reduced conditions (Delta IW = -5 to +1) were obtained by performing 21 high pressure experiments at 1 GPa and 1683-2283 K. The observed Fe-S liquid-silicate melt partitioning behavior is in agreement with thermodynamic models that predict a significant role for 0 in Fe-S liquid and S in the silicate melt.

To assess the viability of sulfide liquid saturation during crystallization of the lunar magma ocean (LMO), we present a new data set describing both the sulfur (S) concentration at sulfide liquid saturation (SCSS) and sulfide liquid-silicate melt partition coefficients of many trace elements for various differentiated lunar magmas at lunar-relevant conditions. Using these parameterizations, we model the SCSS and the distribution of the most chalcophile elements with progressive LMO crystallization in the absence and presence of sulfide liquids. Modeling results for different modes of LMO crystallization show that for proposed lunar mantle S abundances FeS sulfide liquid saturation is expected to occur between 96% and 98% of LMO crystallization. This is decreased to >91% for Fe-S liquids with 30% Ni or Cu. Saturation of S-poor sulfide liquids can occur at >75% of LMO crystallization. The timing of sulfide liquid saturation depends most strongly on the assumed S content of the lunar mantle following formation of the lunar core and on the sulfide liquid composition. Modeled abundances of chalcophile elements indicate that sulfide-liquid saturation during late-stage LMO crystallization would yield much lower abundances of Ni and Cu than observed in KREEP basalts and estimated for the urKREEP reservoir, as well as lower Ni/Co than observed in the latter. Sulfide liquids therefore did not affect moderately siderophile and chalcophile element fractionation within the LMO, supporting the hypothesis that the nonvolatile, siderophile element abundances of the lunar mantle reflect a phase of core formation and/or the addition of a meteoritic late veneer.

Meteoritical Bulletin 109 contains the 2790 meteorites approved by the Nomenclature Committee of the Meteoritical Society in 2020. It includes 17 falls (Al Farciya, Auckland, Cavezzo, Flensburg, Gatuto, Kolang, Mahadeva, Matarka, Narashino, Novo Mesto, Oslo, Saint-Ouen-en-Champagne, Santa Filomena, Tarda, Tiros, Wad Lahteyba, Zhob), with 2336 ordinary chondrites, 131 carbonaceous chondrites (including 8 ungrouped ones), 123 HED achondrites, 41 Martian meteorites, 35 lunar meteorites, 23 iron meteorites, 21 ureilites, 17 primitive achondrites, 13 ungrouped achondrites, 12 mesosiderites, 12 Rumuruti chondrites, 9 enstatite chondrites, 8 pallasites, 4 unclassified meteorites (identified at the surface of Mars), 3 enstatite achondrites, 1 angrite, and 1 ungrouped chondrite. One thousand five hundred and forty-one are from Antarctica, 763 from Africa, 297 from South America, 127 from Asia, 31 from North America, 11 from Europe, 10 from Oceania, 9 from Mars, and 1 from an unknown location.

Deciphering the evolution of ecological interactions among the metabolic types during the early diversification of life on Earth is crucial for our understanding of the ancient biosphere. The stromatolites from the genus Conophyton cylindricus represent a datum for the Proterozoic (Meso to Neoproterozoic) on Earth. Their typical conical shape has been considered a result of a competition between microorganisms for space, light and nutrients. Well-preserved records of this genus from the "Paleontological Site of Cabeludo ", Vazante Group, Sao Francisco Craton (Southern Brazil) present in situ fossilized biofilms, containing preserved carbonaceous matter. Petrographic and geochemical analyses revealed an alternation between mineral laminae (light grey laminae) and fossilized biofilms (dark grey laminae). The dark grey laminae comprise three different biofilms recording a stratified microstructure of microbial communities. These three biofilms composing the dark grey laminae tend to be organized in a specific pattern that repeats through the stromatolite vertical section. Iron and manganese are distributed differently along the dark and light grey laminae; X-ray absorption and luminescence data showed possible different areas with authigenic iron and iron provided from diagenetic infiltration. Cryptocrystalline apatite in the lowermost biofilms in each dark grey laminae may suggest past metabolic activity of sulfide-oxidizing bacteria. These findings suggest that the microorganisms reached a complex metabolic diversification in order to maintain an equilibrium situation between the three different biofilms along the vertical section of the structures, thus benefiting the whole microbial community. This means that the stromatolites from the Conophyton genus may have formed as a result of a greater complexity of interactions between microorganisms, and not only from competition between photosynthesizers.

Estimates of the oxidation states of magmas are important to current investigations of the geochemical characteristics of their source regions and of evolved magmatic series created during differentiation. One means of achieving such estimates is to capitalize on compositions of coexisting cubic and rhombohedral Fe-Ti oxides determined by electron microprobe. A combination of experimental calibration points and thermodynamic modeling provides a basis for translating such compositions into T-f(O2) values. This has been done until recently by estimating Fe3+/Sigma Fe on the basis of charge balance and stoichiometry by the method of Droop (1987), after matrix corrections of X-ray intensity data have been performed, as EPMA cannot be used routinely to distinguish different elemental valence states, much less accurately quantify abundances of Fe3+ and Fe2+. The traditional approach of undertaking post-data-reduction calculations falls short of attaining the best possible quantitative results. The tactical choice of not accounting for light elements that have not been explicitly analyzed prior to matrix corrections of X-ray intensity data leads to systematic errors in reported oxide abundances for measured elements. This article addresses one such issue, the oxygen associated with Fe3+ (hereafter "excess oxygen"), on the basis of coexisting Fe-Ti oxides from Andean lavas. A new software routine in probe for EPMA (PFE) uses an iterative calculation scheme to calculate amounts of excess oxygen that would not be considered if all iron were assumed to be ferrous and then applies this excess oxygen during matrix corrections. The PFE approach reveals that Fe-concentrations have been underestimated, universally, in these minerals because O atoms absorb FeKa radiation: discrepancies increase as total Fe and Fe3+/Fe2+, hence excess oxygen, increase. Analyses of the most Fe-rich cubic oxide compositions in this data set have similar to 6 wt% excess oxygen and similar to 1 wt% more FeO+Fe2O3 than would be reported without incorporating the impact of excess oxygen in matrix corrections. Minor to negligible differences in other elements are also observed. These effects are not because excess oxygen is directly attributed to these elements, although some may be present in multiple valence states, as matrix corrections are undertaken on the basis of the conventional assumptions that they occur as Cr3+, V3+, Mn2+, Mg2+, Ca2+, and Si4+. Rather, variably small increases in total Fe propagate through the matrix corrections for other elements, and these differences may be recorded as minor increases or decreases in some concentrations, depending on the particular element and the amount of change in Fe-concentration. Fe3+/Sigma Fe in analyses produced with the PFE routine are essentially identical to those determined in the traditional mode, as cation proportions calculated on the basis of charge balance and stoichiometry, with the method of Droop (1987), is a necessary step. The new method: (1) provides more accurate concentrations, mainly for Fe and Ti; (2) is applicable to any mineral containing ferric iron (subject to stoichiometric constraints); (3) provides more accurate analytical totals, which can be advantageous for evaluating analytical quality; and (4) does not impact estimates of oxidation state.