Chang'E-5 samples provide unique insights into the composition of the lunar interior similar to 2 billion years ago, but geochemical models of their formation show a significant degree of discrepancy. Trace element abundance measurements in olivine grains in Chang'E-5 sub-sample CE5C0600YJFM002GP provide additional constraints on the basalt source. Geochemical modeling indicates that low-degree (4 %) batch melting of an olivine-pyroxenite lunar magma ocean cumulate, incorporating high levels of trapped lunar magma ocean liquid and plagioclase, can reproduce the rare earth element, Sr, Rb, Sc, Co and Ni abundances in our and previously reported Chang'E-5 samples, as well as observed Rb-Sr and Sm-Nd isotope systematics. Overall, these results strengthen the direct geochemical links between lunar magma ocean evolution and basaltic volcanism occurring similar to 2.5 billion years later. Additionally, Chang'E-5 high-Fo olivine is enriched in the volatile element Ge (1.38-3.94 mu g/g) by similar to 2 orders of magnitude compared to modeled results (< 0.02 mu g/g). As Ge is a mildly compatible element with bulk Ge partition coefficients close to 1, a Ge-depleted initial LMO proposed by previous research cannot yield a high-Ge mantle source for Chang'E-5 basalt, even when invoking assimilation of high-Ge LMO cumulates. The overabundance of Ge requires either a high-Ge, volatile rich initial bulk Moon with chondritic composition or a late Ge chloride vapor-phase metasomatism.

The H2O concentration and H2O/Ce ratio in olivine-hosted melt inclusions are high in lunar pyroclastic sample 74220 (H2O up to 1410 ppmw; H2O/Ce up to 77) but lower (H2O 10 to 430 ppmw; H2O/Ce 0.3 to 9.4) in all other lunar samples studied before this work. The difference in H2O concentration and in H2O/Ce ratio is absent for other volatile elements (F, S, and Cl) in melt inclusions in 74220 and other lunar samples. Because H2O (or H) is a critical volatile component with significant ramifications on the origin and evolution of the Moon, it is important to understand what causes such a large gap in H2O/Ce ratio between 74220 and other lunar samples. Two explanations have been advanced. One is that volcanic product in sample 74220 has the highest cooling rate and thus best preserved H2O in melt inclusions compared to melt inclusions in other samples. The other explanation is that sample 74220 comes from a localized heterogeneity enriched in some volatiles. To distinguish these two possibilities, here we present new data from two rapidly cooled lunar samples with glassy melt inclusions: olivine-hosted melt inclusions (OHMIs) in 79135 regolith breccia (unknown cooling rate but with glassy MIs similar in texture with those in 74220), and pyroxene-hosted melt inclusions (PHMIs) in 15597 pigeonite basalts (known high cooling rate, second only to 74220 and 15421). In addition, we also investigated new OHMIs in sample 74220. If the gap is due to the difference in cooling rates, samples with cooling rates between those of 74220 and other studied lunar samples should have preserved intermediate H2O concentrations and H2O/Ce ratios. Our results show that melt inclusions in 79135 and 15597 contain high H2O concentrations (up to 969 ppmw in 79135 and up to 793 ppmw in 15597) and high H2O/Ce ratios (up to 21 in 79135 and up to 13 in 15997), bridging the big gap in H2O/Ce ratio among 74220 and other lunar samples. Combined with literature data, we confirm that H2O/Ce ratios of different lunar samples are positively correlated to the cooling rates and independent of the type of mare basalts. We hence reinforce the interpretation that the lunar sample with the highest cooling rate best represents pre-eruptive volatiles in lunar basalts due to the least degassing. Based on Ce concentration in the primitive lunar mantle, we estimate that H2O concentration in the primitive lunar mantle (meaning bulk silicate Moon) is 121 +/- 15 ppmw. Our new data also further constrain F/P, S/Dy and Cl/Ba ratios in lunar basalts and the lunar mantle. Estimated F, P, and S concentrations in the lunar primitive mantle are 4.4 +/- 1.1 ppmw, 22 +/- 8 ppmw, and 67+67 33 ppmw, respectively.

As anthropogenic forcing continues to rapidly modify worldwide climate, impacts on landscape changes will grow. Olivine weathering is a natural process that sequesters carbon out of the atmosphere, but is now being proposed as a strategy that can be artificially implemented to assist in the mitigation of anthropogenic carbon emissions. We use the landscape evolution model Badlands to identify a region (Tweed Caldera catchment in Eastern Australia) that has the potential for naturally enhanced supply of mafic sediments, known to be a carbon sink, into coastal environments. Although reality is more complex than what can be captured within a model, our models have the ability to unravel and estimate how erosion of volcanic edifices and landscape dynamics will react to future climate change projections. Local climate projections were taken from the Australian government and the IPCC in the form of four alternative pathways. Three additional scenarios were designed, with added contributions from the Antarctic Ice Sheet, to better understand how the landscape/dynamics might be impacted by an increase in sea level rise due to ice sheet tipping points being hit. Three scenarios were run with sea level held constant and precipitation rates increased in order to better understand the role that precipitation and sea level plays in the regional supply of sediment. Changes between scenarios are highly dependent upon the rate and magnitude of climatic change. We estimate the volume of mafic sediment supplied to the erosive environment within the floodplain (ranging from similar to 27 to 30 million m(3)by 2100 and similar to 78-315 million m(3)by 2500), the average amount of olivine within the supplied sediment under the most likely scenarios (similar to 7.6 million m(3)by 2100 and similar to 30 million m(3)by 2500), and the amount of CO(2)that is subsequently sequestered (similar to 53-73 million tons by 2100 and similar to 206-284 million tons by 2500). Our approach not only identifies a region that can be further studied in order to evaluate the efficacy and impact of enhanced silicate weathering driven by climate change, but can also help identify other regions that have a natural ability to act as a carbon sink via mafic rock weathering.

Titanium dioxide (TiO2) is one of the most studied oxides in photocatalysis, due to its electronic structure and its wide variety of applications, such as gas sensors and biomaterials, and especially in methane-reforming catalysis. Titanium dioxide and olivine have been detected both on Mars and our Moon. It has been postulated that on Mars photocatalytic processes may be relevant for atmospheric methane fluctuation, radicals and perchlorate pro-ductions etc. However, to date no investigation has been devoted to modelling the properties of TiO2 adsorbed on olivine surface. The goal of this study is to investigate at atomic level with electronic structure calculations based on the Density Functional Theory (DFT), the atomic interactions that take place during the adsorption processes for formation of a TiO regolith. These models are formed with different titanium oxide films adsorbed on olivine (forsterite) surface, one of the most common minerals in Universe, Earth, Mars, cometary and interstellar dust. We propose three regolith models to simulate the principal phases of titanium oxide (TiO, Ti2O3 and TiO2). The models show different adsorption processes Le. physisorption and chemisorption. Our results suggest that the TiO is the most reactive phase and produces a strong exothermic effect. Besides, we have detailed, from a theoretical point of view, the effect that has the adsorption process in the electronic properties such as electronic density of states (DOS) and oxide reduction process (redox). This theoretical study can be important to understand the formation of new materials that can be used as support in the catalytic processes that occur in the Earth, Mars and Moon. Also, it may be important to interpret the present day photochemistry and interaction of regolith and airborne aerosols in the atmosphere on Mars or to define possible catalytic reactions of the volatiles captured on the Moon regolith.

How water could affect thermal transport properties is a key question that needs to be quantified experimentally when it is incorporated as structurally bound hydroxyl groups in the lattice of mantle minerals. In this study, thermal diffusivity (D) and thermal conductivity (kappa) of San Carlos olivine aggregates with various water contents (up to 0.2 wt.% H2O) were measured simultaneously using transient plane-source method up to 873 K and 3 GPa. Experimental results demonstrate that water content can significantly reduce the thermal diffusivity (D) and thermal conductivity (kappa) of olivine aggregate. With the increase of H2O content from 0.08 to 0.2 wt.%, the absolute values of D and kappa for olivine samples decrease by 5-13% and 17-33% and by 3-8% and 14-21%, respectively. D and kappa of olivine aggregate decrease with temperature but increase with pressure. Heat capacity is influenced by pressure negatively. Combining the present data with surface heat flow of the Moon as well as heat production, the calculated temperature profiles provide new constraints on the lunar geotherm and possible H2O content in the lunar interior.

While it is now recognized that the Moon has indigenous water and volatiles, their total abundances are unclear, with current literature estimates ranging from nearly absent to Earth-like levels. Similarly unconstrained is the source of the Moon's water, which could be cometary, chondritic, or the primordial nebula. Here we measure H2O and D/H in olivine-hosted melt inclusions in lunar mare basalts 12018, 12035, and 12040, part of the consanguineous suite of Apollo 12 olivine basalts that differ primarily because of cooling rate (Walker et al., 1976). We find that the water contents are higher in the more rapidly cooled 12018 (62-740 ppm H2O) compared to the more slowly cooled basalts 12035 (28-156 ppm H2O) and 12040 (27-90 ppm H2O), suggesting that lunar basalts may have been dehydrating during slow cooling. D/H is similar in the olivine-hosted melt inclusions in all three samples, and indistinguishable from terrestrial water (dD = -183 +/- 212% to + 138 +/- 61%). When we compare the D/H of olivine-hosted melt inclusions to D/H of apatite in the same samples, the evolution of dD and water content can be better constrained. We propose that lunar magmas first exchange hydrogen with a low D/H reservoir during cooling, and then ultimately lose their water during extended subsolidus cooling. Due to high diffusion rates of hydrogen in olivine, it is likely that all basaltic olivine-hosted melt inclusions from the Moon exchanged hydrogen with a low D/H reservoir in near-surface magma chambers or lava flows. The most likely source of the low D/H reservoir on the Moon is the lunar regolith, which is known to have a significant solar wind hydrogen component.