The source and nature of carbon on Mars have been a subject of intense speculation. We report the results of confocal Raman imaging spectroscopy on 11 martian meteorites, spanning about 4.2 billion years of martian history. Ten of the meteorites contain abiotic macromolecular carbon (MMC) phases detected in association with small oxide grains included within high-temperature minerals. Polycyclic aromatic hydrocarbons were detected along with MMC phases in Dar al Gani 476. The association of organic carbon within magmatic minerals indicates that martian magmas favored precipitation of reduced carbon species during crystallization. The ubiquitous distribution of abiotic organic carbon in martian igneous rocks is important for understanding the martian carbon cycle and has implications for future missions to detect possible past martian life.

Samoan shield-stage lavas (from the islands of Ta'u, Savai'i, and Ofu and the seamounts of Vailulu'u and Malumalu) with Os concentrations >30 ppt have Os-187/Os-188 ratios that exhibit a narrow range of values between 0.128 and 0.132. Lavas with <= 30 ppt Os show more radiogenic Os-187/Os-188 ratios, in some cases as high as 0.191, suggesting that the Os-187/Os-188 ratios of the extreme Samoan EM2 (enriched mantle 2) lavas likely have been compromised by assimilation of altered oceanic crust. The Os-187/Os-188 ratios for rejuvenated-stage lavas from Savai'i are lower than shield lavas, and they exhibit some of the lowest Os-187/Os-188 ratios in the global ocean island basalt database (Hauri and Hart, 1993). The difference may owe to contamination of the rejuvenated lavas with unradiogenic Os from disaggregated xenoliths from the mantle lithosphere, and their low Os isotopic composition does not reflect the EM2 mantle source of magmas. The limited range in (OS)-O-187/(OS)-O-188 ratios of the higher Os-abundance shield lavas (0.128-0.132), coupled with a tremendous range of Sr-87/Sr-86 (0.7045-0.7114), are characteristics of the EM2 source that can be explained by mixing a continental crustal sediment characterized by a high Sr/Os (similar to 10(7)) with a mantle peridotite that has low Sr/Os (similar to 10(4)).

Minerals containing chromium (Cr) as an essential element display systematic trends in their diversity and distribution. We employ data for 72 approved terrestrial Cr mineral species (http://rruff. info/ima, as of 15 April 2016), representing 4089 mineral species-locality pairs (http://mindat. org and other sources, as of 15 April 2016). We find that Cr-containing mineral species, for which 30% are known at only one locality and more than half are known from three or fewer localities, conform to a Large Number of Rare Events (LNRE) distribution. Our model predicts that at least 100 +/- 13 (1s) Cr minerals exist in Earth's crust today, indicating that 28 +/- 13 (1s) species have yet to be discovered-a minimum estimate because our model assumes that new minerals will be found only using the same methods as in the past. Numerous additional Cr minerals likely await discovery using micro-analytical methods.

A fundamental goal of mineralogy and petrology is the deep understanding of mineral phase relationships and the consequent spatial and temporal patterns of mineral coexistence in rocks, ore bodies, sediments, meteorites, and other natural polycrystalline materials. The multi-dimensional chemical complexity of such mineral assemblages has traditionally led to experimental and theoretical consideration of 2-, 3-, or n-component systems that represent simplified approximations of natural systems. Network analysis provides a dynamic, quantitative, and predictive visualization framework for employing "big data" to explore complex and otherwise hidden higher-dimensional patterns of diversity and distribution in such mineral systems. We introduce and explore applications of mineral network analysis, in which mineral species are represented by nodes, while coexistence of minerals is indicated by lines between nodes. This approach provides a dynamic visualization platform for higher-dimensional analysis of phase relationships, because topologies of equilibrium phase assemblages and pathways of mineral reaction series are embedded within the networks. Mineral networks also facilitate quantitative comparison of lithologies from different planets and moons, the analysis of coexistence patterns simultaneously among hundreds of mineral species and their localities, the exploration of varied paragenetic modes of mineral groups, and investigation of changing patterns of mineral occurrence through deep time. Mineral network analysis,

Single sulfides from abyssal peridotites have been analyzed for Pb and Re-Os to constrain the evolution of oceanic mantle composition. These represent the first analyses of Pb and Os isotopic compositions in the same sulfide grain. The sulfides are from Gakkel and Southwest Indian ridge peridotites, occur at < 0.1% modal abundances, and contain 0.001-0.4 ppm Re, 0.003-5 ppm Os, and 0.12-12 ppm Pb. Sulfide Pb isotopic compositions extend from depleted (e.g., Pb-206/Pb-204=17.0) to enriched (19.6), covering a larger range than associated basalts. The Os isotopic range of sulfides is more restricted, but extends from depleted (Os-187/Os-188 = 0.116) to enriched (0.150). Pb and Os concentrations and isotopic compositions co-vary, with correlation coefficients of 0.76-0.94. Both Pb and Re-Os isotopic data follow similar to 2 Ga isochrons, with isotopic compositions varying down to small ( << 1 km) length-scales and some sulfides containing supra-chondritic Re-187/Os-188 and Os-187/Os-188. These observations are best explained by long-term recycling of oceanic lithosphere combined with melt extraction and refertilization at ancient ocean ridges, rather than a specific event at 2 Ga.

Planets and minor bodies such as asteroids, Kuiper-Belt objects, and comets are integral components of a planetary system. Interactions among them leave clues about the formation process of a planetary system. The signature of such interactions is most prominent through observations of its debris disk at millimeter wavelengths where emission is dominated by the population of large grains that stay close to their parent bodies. Here we present ALMA 1.3 mm observations of HD. 95086, a young early-type star that hosts a directly imaged giant planet b and a massive debris disk with both asteroid-and Kuiper-Belt analogs. The location of the Kuiper-Belt analog is resolved for the first time. The system can be depicted as a broad (Delta R/R similar to 0.84), inclined (30 degrees +/- 3 degrees) ring with millimeter emission peaked at 200 +/- 6 au from the star. The 1.3 mm disk emission is consistent with a broad disk with sharp boundaries from 106 +/- 6 to 320 +/- 20 au with a surface density distribution described by a power law with an index of -0.5 +/- 0.2. Our deep ALMA map also reveals a bright source located near the edge of the ring, whose brightness at 1.3 mm and potential spectral energy distribution are consistent with it being a luminous star-forming galaxy at high redshift. We set constraints on the orbital properties of planet b assuming coplanarity with the observed disk.

It has been more than two decades since diamond ages have proven to be up to billions of years older than their host magmas of kimberlite or lamproite. Since then, there have been significant advances in the analysis of diamonds and their mineral inclusions, in the understanding of diamond-forming fluids in the mantle, and in the relationship of diamonds to the deep geology of the continents and the convecting mantle. The occurrence of natural diamonds is remarkable and important to earth studies. This article reviews current thinking of where, how, when, and why natural diamonds form.

The Mars Science Laboratory Curiosity rover has been traversing strata at the base of Aeolis Mons (informally known as Mount Sharp) since September 2014. The Murray formation makes up the lowest exposed strata of the Mount Sharp group and is composed primarily of finely laminated lacustrine mudstone intercalated with rare crossbedded sandstone that is prodeltaic or fluvial in origin. We report on the first three drilled samples from the Murray formation, measured in the Pahrump Hills section. Rietveld refinements and FULLPAT full pattern fitting analyses of X-ray diffraction patterns measured by the MSL CheMin instrument provide mineral abundances, refined unit-cell parameters for major phases giving crystal chemistry, and abundances of X-ray amorphous materials. Our results from the samples measured at the Pahrump Hills and previously published results on the Buckskin sample measured from the Marias Pass section stratigraphically above Pahrump Hills show stratigraphic variations in the mineralogy; phyllosilicates, hematite, jarosite, and pyroxene are most abundant at the base of the Pahrump Hills, and crystalline and amorphous silica and magnetite become prevalent higher in the succession. Some trace element abundances measured by APXS also show stratigraphic trends; Zn and Ni are highly enriched with respect to average Mars crust at the base of the Pahrump Hills (by 7.7 and 3.7 times, respectively), and gradually decrease in abundance in stratigraphically higher regions near Marias Pass, where they are depleted with respect to average Mars crust (by more than an order of magnitude in some targets). The Mn stratigraphic trend is analogous to Zn and Ni, however, Mn abundances are close to those of average Mars crust at the base of Pahrump Hills, rather than being enriched, and Mn becomes increasingly depleted moving upsection. Minerals at the base of the Pahrump Hills, in particular jarosite and hematite, as well as enrichments in Zn, Ni, and Mn, are products of acid-sulfate alteration on Earth. We hypothesize that multiple influxes of mildly to moderately acidic pore fluids resulted in diagenesis of the Murray formation and the observed mineralogical and geochemical variations. The preservation of some minerals that are highly susceptible to dissolution at low pH (e.g., mafic minerals and fluorapatite) suggests that acidic events were not long-lived and that fluids may not have been extremely acidic (pH > 2). Alternatively, the observed mineralogical variations within the succession may be explained by deposition in lake waters with variable Eh and/or pH, where the lowermost sediments were deposited in an oxidizing, perhaps acidic lake setting, and sediments deposited in the upper Pahrump Hills and Marias Pass were deposited lake waters with lower Eh and higher pH. Published by Elsevier B.V.

Proterozoic anorthosites from the 1630-1650 Ma Mealy Mountains Intrusive Suite (Grenville Province, Canada), the 1289-1363 Ma Nain Plutonic Suite (Nain-Churchill Provinces, Canada) and the 920-949 Ma Rogaland Anorthosite Province (Sveconorwegian Province, Norway), all entrain comagmatic, cumulate, high-alumina orthopyroxene megacrysts (HAOMs). The orthopyroxene megacrysts range in size from 0.2 to 1 m and all contain exsolution lamellae of plagioclase that indicate the incorporation of an excess Ca-Al component inherited from the host magma at pressures in excess of 10 kbar at or near Moho depths (>30-40 km). Suites of HAOMs from each intrusion display a large range in Sm-147/Nd-144 (0.10 to 0.34) making them amenable for precise age dating with the Sm-Nd system. Sm-Nd isochrons for HAOMs give ages of 1765 +/- 12 Ma (Mealy Mountains), 1041 +/- 17 Ma (Rogaland) and 1444 +/- 100 Ma (Nain), all of them older by about 80 to 120 m.y. than the respective 1630-1650, 920-949 and 1289-1363 Ma crystallization ages of their host anorthosites. Internal mineral Sm-Nd isochrons between plagioclase exsolution lamellae and the orthopyroxene host for HAOMs from the Rogaland and Nain complexes yield ages of 968 +/- 43 and 1347 +/- 6 Ma, respectively - identical within error to the ages of the anorthosites themselves. This age concordance establishes that decompression exsolution in the HAOM was coincident with magmatic emplacement of the anorthosites, similar to 100 m.y. after HAOMs crystallization at the Moho. Correspondence of Pb isotope ages (Pb-206/Pb-204 vs. Pb-207/Pb-204)) with Sm-Nd ages and other strong lines of evidence indicate that the older megacryst ages represent true crystallization ages and not the effects of time-integrated mixing processes in the magmas. Nd isotopic evolution curves, AFC/mixing calculations and the age relations between the HOAMs and their anorthosite hosts show that the HAOMs are much less contaminated with crustal components and are an older part of the same magmatic system from which the anorthosites are derived. Modeling of these anorthositic magmas with MELTS indicates that their ultramafic cumulates would have sunk in the magma and been sequestered at the Moho, where they may have sunk deeper into the mantle resulting in large-scale compositional differentiation. The HAOMs thus represent a rare example of part of a cumulate assemblage that was carried to the upper crust during anorthosite emplacement and, together with the anorthosites, illustrate the dramatic influence that magma ponding and differentiation at the Moho has on residual magmas traveling towards the surface. The new geochronologic and isotopic data indicate that the magmas were derived by melting of the mantle, forming magmatic systems that could have been long-lived (e.g. 80-100 my.). A geologic setting that would fit these temporal constraints is a long-lived Andean-type margin. (C) 2013 Elsevier B.V. All rights reserved.

The Mars rover Curiosity in Gale crater conducted the first-ever direct chemical and mineralogical comparisons of samples that have clear parent (unaltered) and daughter (altered) relationships. The mineralogy and chemistry of samples within and adjacent to alteration halos in a sandstone formation were established by the Chemistry and Mineralogy (CheMin) X-ray diffraction (XRD) instrument and the Alpha Particle X-ray Spectrometer (APXS), respectively. The Stimson formation sandstones unconformably overlie the Murray mudstone formation and represent the youngest stratigraphic unit explored by Curiosity to date. Aqueous alteration of the parent sandstone resulted in a loss of half of the original crystalline mineral phases and a three-fold increase in X-ray amorphous material. Aqueous fluids extensively leached Mg, Al, Mn, Fe, Ni, Zn and other elements from the parent material, decreased the pyroxene to feldspar ratio by a factor of two, introduced Ca and mixed-cation sulfates, and both passively and actively enriched the silica content. Leaching of Mg, Al, Mn, Fe, Ni and Zn and enrichment of Si and S are also observed in alteration halos in the underlying mudstone. These observations are consistent with infiltration of subsurface fluids, initially acidic and then alkaline, propagating along fractures crosscutting the Stimson sandstone and Murray mudstone. The geochemistry and mineralogy suggest a complicated diagenetic history with multiple stages of aqueous alteration under a variety of environmental conditions (e.g. both low and moderate pH). The formation of these alteration halos post-dates lithification of the sandstones and mudstones and represents one of the youngest hydrogeologic events presently known to have occurred in Gale crater. (C) 2017 The Authors. Published by Elsevier B.V.