Implications of a highly convective lunar magma ocean: insights from phase equilibria modeling

The Moon's internal structure was largely defined within the first 200 million years following the initial Moon-forming impact. During this period, the lunar magma ocean (LMO) lost most of its heat through early vigorous convection, crystallizing and forming an initial cumulate stratigraphy through, potentially, robust equilibrium crystallization followed by fractional crystallization once the LMO became sufficiently viscous. This rheological transition is estimated to have occurred at 50 % to 60 % LMO solidification, and although the petrological effects of the regime switch have been frequently investigated at the lower value, such effects at the upper limit have not been formally examined until now. Given this scenario, we present two new internally consistent, high-resolution models that simulate the solidification of a deep LMO of Earth-like bulk silicate composition at both rheological transition values, focusing on the petrological characteristics of the evolving mantle and crust. The results suggest that increasing the volume of early suspended solids from the oft-examined 50 % to 60 % may lead to non-trivial differences. The appearance of minor mantle garnet without the need to invoke a refractory-element enriched bulk silicate Moon composition, a bulk mantle relatively richer in orthopyroxene than olivine, a lower density upper mantle, and a thinner crust are shown to change systematically between the two models, favoring prolonged early crystal suspension. In addition, we show that late-stage, silica-enriched melts may not have sufficient density to permit plagioclase to continue building a floatation crust and that plagioclase likely sinks or stagnates. As the ability of a lunar magma ocean to suspend crystals is directly tied to the Moon's early thermal state, the degree of early LMO convection – and the immediate Solar System environment that drives it – require as much consideration in LMO models as more well-investigated parameters such as bulk silicate Moon composition and initial magma ocean depth

Pre-eruptive magmatic processes re-timed using a non-isothermal approach to magma chamber dynamics

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Acute Toxicity of the Antifouling Compound Butenolide in Non-Target Organisms

Butenolide [5-octylfuran-2(5H)-one] is a recently discovered and very promising anti-marine-fouling compound. In this study, the acute toxicity of butenolide was assessed in several non-target organisms, including micro algae, crustaceans, and fish. Results were compared with previously reported results on the effective concentrations used on fouling (target) organisms. According to OECD's guideline, the predicted no effect concentration (PNEC) was 0.168 µg l−1, which was among one of the highest in representative new biocides. Mechanistically, the phenotype of butenolide-treated Danio rerio (zebrafish) embryos was similar to the phenotype of the pro-caspase-3 over-expression mutant with pericardial edema, small eyes, small brains, and increased numbers of apoptotic cells in the bodies of zebrafish embryos. Butenolide also induced apoptosis in HeLa cells, with the activation of c-Jun N-terminal kinases (JNK), Bcl-2 family proteins, and caspases and proteasomes/lysosomes involved in this process. This is the first detailed toxicity and toxicology study on this antifouling compound

A nickel for your planet's thoughts

International audienceVariability of iron isotopes among planetary bodies may reflect their accretion or differentiation histories. Experiments suggest nickel may be the ingredient controlling iron isotope signatures, supporting fractionation during core formation