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Direct analysis of the composition of Mars is possible through delivery of meteorites to Earth. Martian meteorites include ∼165 to 2400 Ma shergottites, originating from depleted to enriched mantle sources, and ∼1340 Ma nakhlites and chassignites, formed by low degree partial melting of a depleted mantle source. To date, no unified model has been proposed to explain the petrogenesis of these distinct rock types, despite their importance for understanding the formation and evolution of Mars. Here we report a coherent geochemical dataset for shergottites, nakhlites and chassignites revealing fundamental differences in sources. Shergottites have lower Nb/Y at a given Zr/Y than nakhlites or chassignites, a relationship nearly identical to terrestrial Hawaiian main shield and rejuvenated volcanism. Nakhlite and chassignite compositions are consistent with melting of hydrated and metasomatized depleted mantle lithosphere, whereas shergottite melts originate from deep mantle sources. Generation of martian magmas can be explained by temporally distinct melting episodes within and below dynamically supported and variably metasomatized lithosphere, by long-lived, static mantle plumes., A unified model for the formation of martian rock types is required to understand Mars’s formation and evolution. Here the authors show that nakhlite and chassignite meteorites originate from melting of metasomatized depleted mantle lithosphere, whereas shergottite melts originate from deep plume sources.

Quantitative textural analysis is a powerful tool in the investigation of basalt crystallization. We present the first comprehensive crystal size distribution analysis of Apollo 17 high-titanium lunar basalts, with a focus on ilmenite. Crystal size distributions of ilmenite, pyroxene, plagioclase, olivine and armalcolite were determined for 18 high-Ti mare basalt samples from the Apollo 17 mission. A subset of the ilmenite size distribution (size bins of

The development of the Global Exploration Roadmap (GER) by 12 space agencies participating in the International Space Exploration Coordination Group broadly outlines a pathway to send humans beyond low Earth orbit for the first time since Apollo. Three themes have emerged: Exploration of a Near-Earth Asteroid, Extended Duration Crew Missions, and Humans to the Lunar Surface. The lack of detail within each of these themes could mean that realizing the goals of the GER would be significantly delayed. The purpose of this paper is to demonstrate that many of the details needed to fully define and evaluate these themes in terms of scientific rationale, economic viability, and technical feasibility already exist and need to be mapped to the GER. Here, we use the Humans to the Lunar Surface theme as an example to illustrate how this process could work. By mapping documents from a variety of international stakeholders, this process can be used to cement buy-in from the current partners and attract new ones to this effort.

Aside 2 from Earth, the inner solar system is like a vast desert where water and other volatiles are scarce. An old saying is, “In the desert, gold is useless and water is priceless.” While water is common on Earth, it is of very high value in space. Science missions to the Moon have provided direct evidence that regions near the lunar poles, which are permanently in shadow, contain substantial concentrations of water ice. On the lunar surface, water itself is critical for human consumption and radiation shielding, but water can also be decomposed into hydrogen and oxygen via electrolysis. The oxygen thus produced can be used for life support, and hydrogen and oxygen can be combusted for rocket propulsion. Due to the Moon’s shallow gravity well, its water-derived products can be exported to fuel entirely new economic opportunities in space. This paper is the result of an examination by industry, government, and academic experts of the approach, challenges, and payoffs of a private business that harvests and processes lunar ice as the foundation of a lunar, cislunar (between the Earth and the Moon), and Earth-orbiting economy. A key assumption of this analysis is that all work—construction, operation, transport, maintenance and repair—is done by robotic systems. No human presence is required. Obtaining more data on conditions within the shadowed regions is vital to the design of a lunar ice processing plant. How much water is actually present, and at what percentage in the lunar regolith? How firm or soft are the crater bottoms, and how will that affect surface transportation? How deep is the ice resource, and in what state is it deposited amongst the regolith? These and other questions must be answered by precursor prospecting and science missions. A wide range of potential customers for the hydrogen and oxygen products has been identified. They can be used to fuel reusable landers going back and forth between the lunar surface and lunar orbit. They can make travel to Mars less expensive if the interplanetary vehicle can be refueled in cislunar space prior to departure. Operations closer to Earth can also benefit from this new, inexpensive source of propellant. Refueling in Low Earth Orbit can greatly improve the size, type, and cost of missions to Geosynchronous Earth Orbit and beyond. This study has identified a near term annual demand of 450 metric tons of lunar derived propellant equating to 2450 metric tons of processed lunar water generating $2.4 billion of revenue annually. Unlike terrestrial mining operations that utilize heavy machinery to move resources, the mass constraints of a lunar polar water mine are highly restrictive because of delivery cost. A revolutionary concept has been introduced that solves this issue. It has been discovered that instead of excavating, hauling, and processing, lightweight tents and/or heating augers can be used to extract the water resource directly out of the regolith in place. Water will be extracted from the regolith by sublimation—heating ice to convert it into water vapor without going through the liquid phase. This water vapor can then be collected on a cold surface for transport to a processing plant where electrolysis will decompose the water into its constituent parts (hydrogen and oxygen). To achieve production demand with this method, 2.8 megawatts of power is required (2 megawatts electrical and 0.8 megawatts thermal). The majority of the electrical power will be needed in the processing plant, where water is broken down into hydrogen and oxygen. This substantial amount of power can come from solar panels, sunlight reflected directly to the extraction site, or nuclear power. Because the bottoms of the polar craters are permanently shadowed, captured solar energy must be transported from locations of sunlight (crater rim) via power beaming or power cables. Unlike solar power sources, nuclear reactors can operate at any location; however, they generate heat that must be utilized or rejected that may be simplified if located in the cold, permanently shadowed craters. New or exotic technologies have been excluded from this study but may be incorporated into future architectures as they become available. Instead, the equipment described in this lunar propellant operation will be built from existing technologies that have been modified for the specific needs on the Moon. Surprisingly little new science is required to build this plant. Extensive testing on Earth will precede deployment to the Moon, to ensure that the robotics, extraction, chemical processing and storage all work together efficiently. The contributors to this study are those who are currently developing or have already developed the equipment required to enable this capability. From a technological perspective, a lunar propellant production plant is highly feasible. Now is the time to establish the collaborations, partnerships, and leadership that can make this new commercial enterprise a reality. Currently, no one company has all of the capabilities necessary to build the lunar plant, but the capabilities all exist within United States aerospace industry and others (such as the chemical industry). It is necessary that new or existing competing companies establish the leadership needed to coordinate the variety of technologies required for a fully integrated Commercial Lunar Propellant Architecture. Free market competition among these companies will aid in driving down costs, promoting innovation, and expanding the market. To justify such action, a secure customer base, solid business case, and high fidelity economic model is required. This too will help secure the investment required for development and implementation. The initial investment for this operation has been estimated at $4 billion, about the cost of a luxury hotel in Las Vegas. With this investment however, a scalable market can be accessed. As refueling decreases in-space transportation costs, entirely new business and exploration opportunities will emerge with potential to vastly benefit the economies of Earth. Even with the early customers identified within this study, it has been determined that this could be a profitable investment with excellent growth opportunities. The United States Government has critical roles to play in the development of this commercial capability as well. Government science/prospecting and communications missions to the Moon can be very helpful in both the development and operational phases of the business. Government laboratories can contribute some of their technologies and help facilitate integrated systems tests of a terrestrial pilot plant. Government must also work to fill the gaps in international law regarding property rights on celestial bodies such as the Moon. In addition, between Earth orbit, Moon, and Mars missions, government could be an important anchor customer for the resource, stimulating the private sector into action with proposed demands and price points while improving its mission costs and capabilities. This study demonstrates both the technical and economic feasibility of establishing a commercial lunar propellant production capability. It provides recommendations to interested government and private organizations and defines a path to implementation; and explains that by doing so the United States will fuel a new age of economic expansion, sustained space exploration, settlement, and American leadership in space.

Northwest Africa (NWA) 4734 is an unbrecciated basaltic lunar meteorite that is nearly identical in chemical composition to basaltic lunar meteorites NWA 032 and LaPaz Icefield (LAP) 02205. We have conducted a geochemical, petrologic, mineralogic, and Sm-Nd, Rb-Sr, and Ar-Ar isotopic study of these meteorites to constrain their petrologic relationships and the origin of young mare basalts. NWA 4734 is a low-Ti mare basalt with a low Mg* (36.5) and elevated abundances of incompatible trace elements (e.g., 2.00 ppm Th). The Sm-Nd isotope system dates NWA 4734 with an isochron age of 3024 ± 27 Ma, an initial eNd of +0.88 ± 0.20, and a source region 147Sm/144Nd of 0.201 ± 0.001. The crystallization age of NWA 4734 is concordant with those of LAP 02205 and NWA 032. NWA 4734 and LAP 02205 have very similar bulk compositions, mineral compositions, textures, and ages. Their source region 147Sm/144Nd values indicate that they are derived from similar, but distinct, source materials. They probably do not sample the same lava flow, but rather are similarly sourced, but isotopically distinct, lavas that probably originate from the same volcanic complex. They may have experienced slightly different assimilation histories in route to eruption, but can be source-crater paired. NWA 032 remains enigmatic, as its source region 147Sm/144Nd definitively precludes a simple relationship with NWA 4734 and LAP 02205, despite a similar bulk composition. Their high Ti/Sm, low (La/Yb)N, and Cl-poor apatite compositions rule out the direct involvement of KREEP. Rather, they are consistent with low-degree partial melting of late-formed LMO cumulates, and indicate that the geochemical characteristics attributed to urKREEP are not unique to that reservoir. These and other basaltic meteorites indicate that the youngest mare basalts originate from multiple sources, and suggest that KREEP is not a prerequisite for the most recent known melting in the Moon.

Apollo 14 (A-14) impact melt olivine vitrophyres (OVs), composed of olivine phenocrysts in an opaque glass matrix with minor amounts of pyroxene and plagioclase, are petrographically similar to pristine quenched A-14 high-alumina (high-Al) and Apollo 12 (A-12) basalts. Textural and chemical analyses have been conducted on olivines within impact melt and pristine mare basalt clasts from A-14 breccia 14321 as well as various olivine-phyric Apollo 12 and 17 basalts to be able to distinguish between the petrographically similar samples. The A-14 high-Al basalts examined here represent samples from each of the three chemical groups (A, B, C). Examples from the three A-12 basalt suites (Ilmenite, Olivine, Pigeonite) and olivine-rich Apollo 17 (A-17) Type C basalt, 74275, have also been analyzed. As a complement to the chemical analyses, crystal size distributions (CSDs) were determined for approximately half of the samples investigated here (due to a small number of olivine crystals that did not produce statistically meaningful CSDs on half of the samples), and confirm that although similar, the basalts and impact melts are texturally distinct. Olivines from A-14 impact melts have the highest average forsterite contents (average Fo ∼0.82) and generally the lowest average Co (37 ppm) and Mn (1544 ppm) abundances, thus chemically distinguishing them from the pristine basalts. In addition, chemical compositions obtained for olivine from 14321,1486 are most likely representative of an impact melt and thus contradict its previous classification as a high-Al basalt ( Neal et al., 1988 ); olivine from, 1486 have similar average forsterite (average Fo ∼0.82) and Ti/V-ratio to the OVs. Furthermore, on the basis of their chemical compositions, olivines have been identified within the impact melts that are likely inherited from basalts; these olivines are chemically distinct from the rest of the impact melt olivine population with lower forsterite (0.67–0.80) and low Ti/V (∼10), which are similar to olivine compositions from the A-14 high-Al basalts. In addition to distinguishing between sample types from A-14, olivine compositions can also be used to distinguish between pristine mare basalts from various missions. Olivine within the selected samples from the individual A-12 basalt suites can also be distinguished chemically from one another using the Ti/V ratio, where Olivine suite basalts have Ti/V 3.5. The results indicate that combined use of CSDs and chemical analyses of olivine can be used to reliably distinguish between (1) impact melts and pristine Apollo 14 basalts, (2) basalts from different landing sites, and (3) individual basalt suites from a single site.

Water has been detected on the lunar surface and attributed to delivery by impacts and the solar wind to a dry early Moon. Spectroscopic detections of water in lunar anorthosites from the Apollo collection suggest that a significant amount of water is indigenous to the Moon.

As with all science, our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data. This process invigorates the intellectual foundation on which old models are tested and new concepts are built. Just as the application of new observational tools to lunar science in 1610 (Galileo’s telescope) and 1840 (photography) yielded breakthroughs concerning the true nature of the lunar surface, the computational and technological advances highlighted by the Apollo and post-Apollo missions and associated scientific investigations provided a new view of the thermal and magmatic evolution of the Moon. ### 1.1. Pre-Apollo view of the thermal and magmatic evolution of the Moon Many of the early views of the Moon manifested in mythology and art throughout the world were primarily tied to lunar and terrestrial cycles and the relationships between the Sun and the Moon. Prophetically, myths involving the lunar deities Mwuetsi from Zimbabwe and Coyolxauhqui from Mexico told of rather violent or catastrophic events in which the Moon was expunged from the Earth. Numerous ancient scientific observations were made about the nature of the Moon ranging from those uncovered in early Neolithic sites that correctly identified mare Crisium and mare Humorum to the insights made by Greek philosophers such as Anaxagoras (ca. 500-428 B.C.) and Democritus (ca. 460-370 B.C.), who attached terrestrial analogues to its character (stone, mountains). With the advent of the telescope (1610) and photography (1840) as scientific tools for lunar exploration, semiquantitative data could be collected that would provide an intellectual foundation for scientific interpretation. Initially, modern terrestrial geological analogs were extended to the Moon (lunar highlands, volcanic craters, seas). Combined with the rigors of computational modeling, these observational data were extended to predict the original thermal state of the Moon and its thermal and magmatic history. Its proximity to the Earth …

Oceanic plateaus form by mantle processes distinct from those forming oceanic crust at divergent plate boundaries. Eleven drillsites into igneous basement of Kerguelen Plateau and Broken Ridge, including seven from the recent Ocean Drilling Program Leg 183 (1998-99) and four from Legs 119 and 120 (1987-88), show that the dominant rocks are basalts with geochemical characteristics distinct from those of mid-ocean ridge basalts. Moreover, the physical characteristics of the lava flows and the presence of wood fragments, charcoal, pollen, spores and seeds in the shallow water sediments overlying the igneous basement show that the growth rate of the plateau was sufficient to form subaerial landmasses. Most of the southern Kerguelen Plateau formed at ~ 110 Ma, but the uppermost submarine lavas in the northern Kerguelen Plateau erupted during Cenozoic time. These results are consistent with derivation of the plateau by partial melting of the Kerguelen plume. Leg 183 provided two new major observations about the final growth stages of the Kerguelen Plateau. 1: At several locations, volcanism ended with explosive eruptions of volatilerich, felsic magmas; although the total volume of felsic volcanic rocks is poorly constrained, the explosive nature of the eruptions may have resulted in globally significant effects on climate and atmospheric chemistry during the late-stage, subaerial growth of the Kerguelen Plateau. 2: At one drillsite, clasts of garnet-biotite gneiss, a continental rock, occur in a fluvial conglomerate intercalated within basaltic flows. Previously, geochemical and geophysical evidence has been used to infer continental lithospheric components within this large igneous province. A continental geochemical signature in an oceanic setting may represent deeply recycled crust incorporated into the Kerguelen plume or continental fragments dispersed during initial formation of the Indian Ocean during breakup of Gondwana. The clasts of garnet-biotite gneiss are the first unequivocal evidence of continental crust in this oceanic plateau. We propose that during initial breakup between India and Antarctica, the spreading center jumped northwards transferring slivers of the continental Indian plate to oceanic portions of the Antarctic plate. (C) 2000 Published by Elsevier Science B.V. All rights reserved.

The author talks about the importance of returning to the moon in human space exploration. He mentions European Space Agency director general Johann-Dietrich Woener's vision for an international Moon Village. He says exploring the moon would offer useful information that can be used for exploring Mars. He explains the need for robotic prospectors on the lunar surface.

Coupled 187Os/188Os compositions and highly-siderophile-element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundance data are reported for eight angrite achondrite meteorites that include quenched- and slowly-cooled textural types. These data are combined with new major- and trace-element concentrations determined for bulk-rock powder fractions and constituent mineral phases, to assess angrite petrogenesis. Angrite meteorites span a wide-range of HSE abundances from 100 ppb Os (NWA 4931). Chondritic to supra-chondritic 187Os/188Os (0.1201–0.2127) measured for Angra dos Reis and quenched-angrites correspond to inter- and intra-sample heterogeneities in Re/Os and HSE abundances. Quenched-angrites have chondritic-relative rare-earth-element (REE) abundances at 10–15×CI-chondrite, and their Os-isotope and HSE abundance variations represent mixtures of pristine uncontaminated crustal materials that experienced addition (

In response to the growing importance of space exploration in future planning, the Committee on Space Research (COSPAR) Panel on Exploration (PEX) was chartered to provide independent scientific advice to support the development of exploration programs and to safeguard the potential scientific assets of solar system objects. In this report, PEX elaborates a stepwise approach to achieve a new level of space cooperation that can help develop world-wide capabilities in space science and exploration and support a transition that will lead to a global space exploration program. The proposed stepping stones are intended to transcend cross-cultural barriers, leading to the development of technical interfaces and shared legal frameworks and fostering coordination and cooperation on a broad front. Input for this report was drawn from expertise provided by COSPAR Associates within the international community and via the contacts they maintain in various scientific entities. The report provides a summary and synthesis of science roadmaps and recommendations for planetary exploration produced by many national and international working groups, aiming to encourage and exploit synergies among similar programs. While science and technology represent the core and, often, the drivers for space exploration, several other disciplines and their stakeholders (Earth science, space law, and others) should be more robustly interlinked and involved than they have been to date. The report argues that a shared vision is crucial to this linkage, and to providing a direction that enables new countries and stakeholders to join and engage in the overall space exploration effort. Building a basic space technology capacity within a wider range of countries, ensuring new actors in space act responsibly, and increasing public awareness and engagement are concrete steps that can provide a broader interest in space exploration, worldwide, and build a solid basis for program sustainability. By engaging developing countries and emerging space nations in an international space exploration program, it will be possible to create a critical bottom-up support structure to support program continuity in the development and execution of future global space exploration frameworks. With a focus on stepping stones, COSPAR can support a global space exploration program that stimulates scientists in current and emerging spacefaring nations, and that will invite those in developing countries to participate—pursuing research aimed at answering outstanding questions about the origins and evolution of our solar system and life on Earth (and possibly elsewhere). COSPAR, in cooperation with national and international science foundations and space-related organizations, will advocate this stepping stone approach to enhance future cooperative space exploration efforts.

The petrogenesis of Apollo 14 high-Al basaltic melts was studied using crystal stratigraphy, which involves textural (crystal size distributions — CSDs) and chemical analyses (electron microprobe and laser ablation inductively coupled plasma mass spectrometry). The samples studied here include pristine basalt 14072 and basaltic clasts from breccia 14321, and impact-generated crystalline samples 14073, 14276 and 14310. Plagioclase was the focus of this study because of its relatively high modal abundances and because it was on the liquidus for much of the melt cooling histories. Plagioclase crystals were analyzed (core-to-rim compositions where possible) to test and refine petrogenetic models based upon whole-rock compositions (Groups A, B, and C designations) and to investigate basalt 14072 and impact-melt crystallization. Textural studies have shown that each basalt group has distinctive plagioclase CSDs, which are in turn distinctive from those of the impact melts. Evolution of the individual basaltic melts was studied by comparing the equilibrium-melt compositions (calculated from plagioclase compositions using relevant partition coefficients) to fractional crystallization (FC) and assimilation and fractional crystallization (AFC) models. Petrogenetic modeling of trace elements in Group A basalts revealed that petrogenesis continued beyond 40% total crystallization required to model whole-rock compositions, and that there were open-system processes that affected the magma during plagioclase crystallization. Petrogenetic modeling of pristine high-Al basalts (14072 and Groups A, B and C) using trace elements shows that the equilibrium-melt compositions do not fall on a single AFC or FC trajectory. This is consistent with fluctuating degrees of assimilation (i.e., variable r-values) and/or variable assimilant compositions during petrogenesis. Petrogenetic modeling reveals that the impact melts experienced only closed-system fractional crystallization. This work demonstrates the importance of crystal stratigraphy in revealing the intricacies of lunar basalt petrogenesis.

Seven ilmenite (FeTiO3) megacrysts derived from alnoite pipes (Island of Malaita, Solomon Islands) were characterised for their major and trace element compositions in relation to their potential use as secondary reference materials for in situ microanalysis. Abundances of thirteen trace elements obtained by laser ablation ICP-MS analyses (using the NIST SRM 610 glass reference material) were compared with those determined by solution-mode ICP-MS measurements, and these indicated good agreement for most elements. The accuracy of the LA-ICP-MS protocol employed here was also assessed by repeated analysis of MPI-DING international glass reference materials ML3B-G and KL2-G. Several of the Malaitan ilmenite megacrysts exhibited discrepancies between laser ablation and solution-mode ICP-MS analyses, primarily attributed to the presence of a titano-magnetite exsolution phase (at the grain boundaries), which were incorporated solely in the solution-mode runs. Element abundances obtained by LA-ICP-MS for three of the ilmenite megacrysts (CRN63E, CRN63H and CRN63K) investigated here had RSD (2s) values of

Previous investigations of pipe-like intrusions of alnoite within northern Malaita (Solomon Islands) have detailed the chemical and isotopic nature of the alnoite and entrained megacrysts/xenoliths. Alnoite emplacement is poorly constrained since available ages include an Ar–Ar date of 34 Ma (phlogopite) from a mantle xenolith, and a 206Pb/238U date of 33.9 Ma for a zircon megacryst. Hence, we report chemical data, in-situ U–Pb age determinations and Hf isotope compositions for megacrystic zircons recovered from alnoite-derived, ilmenite-rich gravels in the Auluta, Kwainale, and Faufaumela rivers of Malaita. The Zr/Hf ratio (39 to 50) is variable for zircons from Auluta and Faufaumela, whereas it is relatively uniform (40 to 42) in most zircons from Kwainale. Chemical imaging reveals the homogeneous nature for all of the 16 grains analyzed. Trace element compositions obtained by LA-ICP-MS indicate parallel chondrite-normalized REE patterns at variable levels of enrichment; these patterns combined with their low abundances (

The recently recovered paired Antarctic achondrites Graves Nunatak 06128 and 06129 (GRA) are meteorites that represent unique high-temperature asteroidal processes that are identified in only a few other meteorites. The GRA meteorites contain high abundances of sodic plagioclase, relatively Fe-rich pyroxenes and olivine, abundant phosphates, and low temperature alteration. They represent products of very early planetesimal melting (4565.9 +/- 0.3 Ma) of an unsampled geochemical reservoir from an asteroid that has characteristics similar to the brachinite parent body. The magmatism represented by these meteorites is contrary to the commonly held belief that the earliest stages of melting on all planetary bodies during the first 2-30 Ma of solar system history were fundamentally basaltic in nature. These sodic plagioclase-rich rocks represent a series of early asteroidal high-temperature processes: (stage 1) melting and partial extraction of a low-temperature Fe-Ni-S melt, (stage 2) small degrees of disequilibrium partial melting of a sodium- or alkali-rich chondritic parent body with additional incorporation of Fe-Ni-S melt that was not fully extracted during stage 1, (stage 3) volatile-enhanced rapid extraction and emplacement of the Na-rich, high-normative plagioclase melt, (stage 4) final emplacement and accumulation of plagioclase and phosphates, (stage 5) subsolidus reequilibration of lithology between 962 and 600 degrees C at an fO(2) Of IW to IW + 1.1, and (stage 6) replacement of merrillite and pyroxene by Cl-apatite resulting from the interaction between magmatic minerals and a Cl-rich fluid/residuum melt. The subsolidus events started as early as 4561.1 Ma and may have continued for upwards of 144 million years. The existence of assemblages similar to GRA on several other planetary bodies with different geochemical characteristics (ureilite, winonaites, IAB irons) implies that this type of early asteroidal melting was not rare. Whereas, eucrites and angrites represent extensive melting of a parent body with low concentrations of moderately-volatile elements, GRA represents low-degrees of melting of a parent body with chondritic abundances of moderately volatile elements. The interpretation of the low-temperature mineral assemblage is somewhat ambiguous. Textural features suggest multiple episodes of alteration. The earliest stage follows the interaction of magmatic assemblages with a Cl-rich fluid. The last episode of alteration appears to cross-cut the fusion crust and earlier stages or alteration. Stable isotopic measurements of the alteration can be interpreted as indicating that an extraterrestrial volatile component was preserved in GRA. (C) 2009 Elsevier Ltd. All rights reserved.

The Moon likely accreted from melt and vapor ejected during a cataclysmic collision between Proto-Earth and a Mars-sized impactor very early in solar system history. The identical W, O, K, and Cr isotope compositions between materials from the Earth and Moon require that the material from the two bodies were well-homogenized during the collision process. As such, the ancient isotopic signatures preserved in lunar samples provide constraints on the bulk composition of the Earth. Two recent studies to obtain high-precision 142Nd/144Nd ratios of lunar mare basalts yielded contrasting results. In one study, after correction of neutron fluence effects imparted to the Nd isotope compositions of the samples, the coupled 142Nd–143Nd systematics were interpreted to be consistent with a bulk Moon having a chondritic Sm/Nd ratio [Rankenburg K., Brandon A. D. and Neal C. R. (2006) Neodymium isotope evidence for a chondritic composition of the Moon. Science 312, 1369–1372]. The other study found that their data on the same and similar lunar mare basalts were consistent with a bulk Moon having a superchondritic Sm/Nd ratio [Boyet M. and Carlson R. W. (2007) A highly depleted Moon or a non-magma origin for the lunar crust? Earth Planet. Sci. Lett. 262, 505–516]. Delineating between these two potential scenarios has key ramifications for a comprehensive understanding of the formation and early evolution of the Moon and for constraining the types of materials available for accretion into large terrestrial planets such as Earth. To further examine this issue, the same six lunar mare basalt samples measured in Rankenburg et al. [Rankenburg K., Brandon A. D. and Neal C. R. (2006) Neodymium isotope evidence for a chondritic composition of the Moon. Science 312, 1369–1372] were re-measured for high-precision Nd isotopes using a multidynamic routine with reproducible internal and external precisions to better than ±3 ppm (2σ) for 142Nd/144Nd ratios. The measurements were repeated in a distinct second analytical campaign to further test their reproducibility. Evaluation of accuracy and neutron fluence corrections indicates that the multidynamic Nd isotope measurements in this study and the 3 in Boyet and Carlson [Boyet M. and Carlson R. W. (2007) A highly depleted Moon or a non-magma origin for the lunar crust? Earth Planet. Sci. Lett. 262, 505–516] are reproducible, while static measurements in the previous two studies show analytical artifacts and cannot be used at the resolution of 10 ppm to determine a bulk Moon with either chondritic or superchondritic Sm/Nd ratios. The multidynamic data are best explained by a bulk Moon with a superchondritic Sm/Nd ratio that is similar to the present-day average for depleted MORB. Hafnium isotope data were collected on the same aliquots measured for their 142Nd/144Nd isotope ratios in order to assess if the correlation line for 142Nd–143Nd systematics reflect mixing processes or times at which lunar mantle sources formed. Based on the combined 142Nd–143Nd–176Hf obtained we conclude that the 142Nd–143Nd correlation line measured in this study is best interpreted as an isochron with an age of 229+24−20Ma after the onset of nebular condensation. The uncertainties in the data permit the sources of these samples to have formed over a 44 Ma time interval. These new results for lunar mare basalts are thus consistent with a later Sm–Nd isotope closure time of their source regions than some recent studies have postulated, and a superchondritic bulk Sm/Nd ratio of the Moon and Earth. The superchondritic Sm/Nd signature was inherited from the materials that accreted to make up the Earth–Moon system. Although collisional erosion of crust from planetesimals is favored here to remove subchondritic Sm/Nd portions and drive the bulk of these bodies to superchondritic in composition, removal of explosive basalt material via gravitational escape from such bodies, or chondrule sorting in the inner solar system, may also explain the compositional features that deviate from average chondrites that make up the Earth–Moon system. This inferred superchondritic nature for the Earth similar to the modern convecting mantle means that there is no reason to invoke a missing, subchondritic reservoir to mass balance the Earth back to chondritic for Sm/Nd ratios. However, to account for the subchondritic Sm/Nd ratios of continental crust, a second superchondritic Sm/Nd mantle reservoir is required.

With the cancellation of the Apollo program after Apollo 17 returned from the Moon in 1972, the focus of NASA switched to other areas of the Solar System. Study of the Moon did continue through analysis of the returned samples and remotely sensed data sets (both orbital and surface), as well as through Earth-based telescopic studies. In the 1990s, new orbital data were obtained from several missions (fly-by and orbital), the first being Galileo that allowed the lunar farside to be mapped, followed by global mapping by the Clementine and Lunar Prospector missions. Interest in the Moon started to increase at the beginning of the 21st century as other nations focused their space exploration programs on the Moon. The speech by President Bush in January 2004 put the Moon back into the critical exploration path for NASA, paving the way for humans to return to the lunar surface by 2020. This return will be critical for developing technologies and protocols for the eventual human exploration of other parts of the solar system. At the time of writing (June 2008), the SELENE/Kaguya mission (Japan and Chang’e-1 (China) are orbiting the Moon, with Chandrayaan-1 (India) and Lunar Reconnaissance Orbiter (USA) being scheduled to launch later in 2008. The past (and present) exploration of the Moon begs the question ‘‘what’s left to be done?’’ With the renewed focus on the Moon, now that it is on the pathway for the exploration of Mars (and beyond) a similar question has been raised – what should the astronauts do on the Moon? The publication of the New Views of the Moon book [Jolliff et al., 2006. New Views of the Moon, Reviews in Mineralogy, vol. 60. American Mineralogical Society, 721pp] highlighted a number of important scientific questions that remain unanswered as well as posing many more on the basis of the currently available data. These questions resonated in three Lunar Exploration Analysis Group (LEAG) reports pertinent to this discussion, which were also published (on line) during 2006 (http://www.lpi.usra.edu/leag), and in the National Research Council of the National Academies [2007. The Scientific Context for Exploration of the Moon. National Academies Press, Washington, DC, 112pp] report entitled ‘‘The Scientific Context for Exploration of the Moon’’. This paper synthesizes these recent studies, along with those from the 1980s and 1990s, to emphasize the lunar science questions that remain unanswered. In addition, it summarizes the missions already flown to the Moon along with those that are planned in order to give the reader an idea of exactly what lunar science has been and will be conducted in the hope that it will inspire proposals for missions to address the outstanding science questions. r 2008 Elsevier GmbH. All rights reserved.

The recently recovered Antarctic achondrites Graves Nunatak 06128 and 06129 are unique meteorites that represent high-temperature asteroidal processes in the early solar system never before identified in any other meteorite. They represent products of early planetesimal melting (4564.25 ± 0.21 Ma) and subsequent metamorphism of an unsampled geochemical reservoir from an asteroid that has characteristics similar to the brachinite parent body. This melting event is unlike those predicted by previous experimental or geochemical studies, and indicates either disequilibrium melting of chondritic material or melting of chondritic material under volatile-rich conditions.

In the context of sample evidence alone, the high-alumina (HA) basalts appear to be an unique, and rare variety of mare basalt. In addition to their distinct chemistry, radiometric dating reveals these basalts to be among the oldest sampled mare basalts. Yet, HA basalts were sampled by four missions spanning a lateral range of ∼2400 km, with ages demonstrating that aluminous volcanism lasted at least 1 billion years. This evidence suggests that HA basalts may be a widespread phenomenon on the Moon. Knowing the distribution of HA mare basalts on the lunar surface has significance for models of the origin and the evolution of the Lunar Magma Ocean. Surface exposures of HA basalts can be detected with compositional remote sensing data from Lunar Prospector Gamma Ray Spectrometer and Clementine. We searched the lunar surface for regions of interest (ROIs) that correspond to the intersection of three compositional constraints taken from values of sampled HA basalts: 12–18 wt% FeO, 1.5–5 wt% TiO2, and 0–4 ppm Th. We then determined the “true” (unobscured by regolith) composition of basalt units by analyzing the rims and proximal ejecta of small impacts (0.4–4 km in diameter) into the mare surface of these ROIs. This paper focuses on two ROIs that are the best candidates for sources of sampled HA basalts: Mare Fecunditatis, the landing site of Luna 16; and northern Mare Imbrium, hypothesized origin of the Apollo 14 HA basalts. We demonstrate our technique's ability for delineating discrete basalt units and determining which is the best compositional match to the HA basalts sampled by each mission. We identified two units in Mare Fecunditatis that spectrally resemble HA basalts, although only one unit (Iltm) is consistent with the compositional and relative age of the Luna 16 HA samples. Northern Mare Imbrium also reveals two units that are within the compositional constraints of HA basalts, with one (Iltm) best matching the composition of the basalts sampled by Apollo 14.

The effect of natural organic matter (NOM) on arsenic adsorption by a commercial available TiO2 (Degussa P25) in various simulated As(III)-contaminated raw waters was examined. Five types of NOM that represent different environmental origins were tested. Batch adsorption experiments were conducted under anaerobic conditions and in the absence of light. Either with or without the presence of NOM, the arsenic adsorption reached steady-state within 1 h. The presence of 8 mg/L NOM as C in the simulated raw water, however, significantly reduced the amount of arsenic adsorbed at the steady-state. Without NOM, the arsenic adsorption increased with increasing solution pH within the pH range of 4.0–9.4. With four of the NOMs tested, the arsenic adsorption firstly increased with increasing pH and then decreased after the adsorption reached the maximum at pH 7.4–8.7. An appreciable amount of arsenate (As(V)) was detected in the filtrate after the TiO2 adsorption in the simulated raw waters that contained NOM. The absolute amount of As(V) in the filtrate after TiO2 adsorption was pH dependent: more As(V) was presented at pH > 7 than that at pH 7 . The arsenic adsorption in the simulated raw waters with and without NOM were modelled by both Langmuir and Frendlich adsorption equations, with Frendlich adsorption equation giving a better fit for the water without NOM and Langmuir adsorption equation giving a better fit for the waters with NOM. The modelling implies that NOM can occupy some available binding sites for arsenic adsorption on TiO2 surface. This study suggests that in an As(III)-contaminated raw water, NOM can hinder the uptake of arsenic by TiO2, but can facilitate the As(III) oxidation to As(V) at TiO2 surface under alkaline conditions and in the absence of O2 and light. TiO2 thus can be used in situ to convert As(III) to the less toxic As(V) in NOM-rich groundwaters.

Current models for the Moon’s formation have yet to fully account for the thermal evolution of the Moon in the presence of H2O and other volatiles. Of particular importance is chlorine, since most lunar samples are characterised by unique heavy δ37Cl values, significantly deviating from those of other planetary materials, including Earth, for which δ37Cl values cluster around ∼0‰. In order to unravel the cause(s) of the Moon’s unique chlorine isotope signature, we performed a comprehensive study of high-precision in situ Cl isotope measurements of apatite from a suite of Apollo samples with a range of geochemical characteristics and petrologic types. The Cl-isotopic compositions measured in lunar apatite in the studied samples display a wide range of δ37Cl values (reaching a maximum value of +36‰), which are positively correlated with the amount of potassium (K), Rare Earth Element (REE) and phosphorous (P) (KREEP) component in each sample. Using these new data, integrated with existing H-isotope data obtained for the same samples, we are able to place these findings in the context of the canonical lunar magma ocean (LMO) model. The results are consistent with the urKREEP reservoir being characterised by a δ37Cl ∼+30‰. Such a heavy Cl isotope signature requires metal-chloride degassing from a Cl-enriched urKREEP LMO residue, a process likely to have been triggered by at least one large crust-breaching impact event that facilitated the transport and exposure of urKREEP liquid to the lunar surface.

ICP-MS; ICP-OES; Africa; Benin; Regional characterization Summary Groundwater samples were collected at over 100 locations in Benin, West Africa, for the purpose of characterizing region-wide spatial variation in groundwater quality as indicated by concentrations of a number of elements measured within the samples. Analytic techniques ranged from field measures of conductivity and pH, to characterization of major and trace element concentrations using ICP-MS and ICP-OES. Five methods of data analysis were applied to the resulting data set: indicator variables, parameter plots, cluster analysis, variogram analysis, and principal component analysis (PCA). A number of observations are developed from these analyses including regional trends in concentrations and variation of concentration of major and trace elements in specific geologic settings. Perhaps most significant is the identification of a region in the southern portion of the study area where the element chemistry shows high spatial variability. This region had not been identified in prior studies of the regional geochemistry. The mechanisms leading to this variability remain under study. The results presented provide significant insight into the regional variation in groundwater elemental chemistry for Benin. Further, they provide further illustration of the utility of applying multiple data analysis techniques to assessment of regional water quality data sets. a 2007 Elsevier B.V. All rights reserved.

Effect of natural organic matter (NOM) on the stability of inorganic arsenic species in simulated raw water was examined at circumneutral pH. An ion chromatography–inductively coupled plasma mass spectrometry system was used for simultaneous determination of As(III) and As(V). A reduction of arsenate (As(V)) to arsenite (As(III)) was observed in the unfiltered simulated raw waters (USW). The As(V) reduction to As(III) did not occur in the simulated waters that passed through a 0.2 μm membrane (FSW). Microorganism activities is probably the major reason causing As(V) reduction in the USW. In the FSW without NOM, As(III) tended to be oxidized into As(V). The addition of 0.036 mM of Fe(II) significantly facilitated the oxidation. The presence of 10 mg/L Suwannee River NOM as C inhibited As(III) oxidation no matter whether Fe(II) existed or not. The experimental results suggest that NOM can mediate distribution of inorganic arsenic species in water, thus it is an important factor controlling the mobility and toxicity of arsenic in drinking water.

In this paper, we report analysis of various basaltic lunar samples including 14053 and 14072, KREEP basalt 15386, thirty basalt clasts from Apollo 14 breccia 14321, as well as impact-generated samples (matrix from breccia 14168, olivine vitrophyres 14321,1180 and 14321,1539, and impact melt 14310) using a combination of solution and laser ablation inductively coupled plasma mass spectrometry (ICP-MS). The basalt clast samples were previously analyzed by instrumental neutron activation. On plots of incompatible trace elements (ITEs) vs. compatible trace elements, the Apollo 14 high-Al basalts form three approximately subparallel trends that, on the basis of current data, are also separated by age. Plots of ITE ratios (i.e., Nb/Ce vs. Zr/Y) can be used to indicate source composition, and also divide the basalts into three groups: Group A (~4.3 Ga); Group B (~4.1 Ga); and Group C (~3.9 Ga). New data for 14072 suggest the sample does not Þ t with any of the three groups deÞ ned here, and may indicate the presence of a fourth group of high-Al basalts in the proximity of the Apollo 14 site. The Apollo 14 high-Al basalts are compositionally distinct from known Apollo 14 impact melts and impact-generated lithologies. The three groups cannot be related by varying degrees of partial melting of a single, KREEP-contaminated source and, therefore, require three separate source regions. The new data indicate that Group A basalts evolved through closed-system crystal fractionation. However, the new data from basalts forming Groups B and C require open-system evolution that involves combined assimilation and fractional crystallization (AFC). Unlike previous AFC modeling of the Apollo 14 high-Al basalts, an assimilant composed of KREEP is not sufÞ cient to generate the compositional ranges of each basalt group. The modeling of both groups requires a mixture of KREEP and granite as the assimilant, which supports the notion of a genetic relationship between these two lunar components.

Petrologic studies of igneous rocks often rely on whole-rock analyses alone to deduce source and melting histories. Whole-rock compositions represent a mixture of the processes responsible for the final texture and composition of the rock, but do not emphasize the evolutionary processes that the rock may have experienced. We examine the major, minor, and trace element compositions of plagioclase phenocrysts and plagioclase-rich cumulate xenoliths from a sequence of Kwaimbaita pillow basalt and massive flows recovered from Ocean Drilling Program (ODP) Site 1183 on the expansive ∼ 122 Ma Ontong Java Plateau (OJP) and from subaerial outcrops on the island of Malaita, Solomon Islands. These data are used to reconstruct equilibrium liquid compositions to understand magma dynamics, magma evolution, and the distribution basalt types across the OJP. Results reveal that crystals frequently are out of equilibrium with their host basalt. Two distinct compositional zones are present in plagioclase phenocrysts and xenolith crystals — An80–86 and An65–79. Equilibrium magma compositions derived from each of these zones are distinct. In relative terms, the following distinctions are made: An80–86: Sr, Y, and Eu richer, Ba and LREE depleted, higher Sr / Ti, lower Ba/Sr and La / Y; An65–79: Sr, Y, and Eu poorer, Ba and LREE enriched, lower Sr / Ti, higher Ba/Sr and La / Y. We observed several An65–79 parent magmas with higher La / Y, lower Sr, and higher LREE than the majority of An65–79 zones, which suggests that they grew from highly fractionated magmas. The An80–86 zones of both xenolith crystals and phenocrysts appear to have crystallized relatively early and are attributed to growth in magmas more primitive than parent magmas of An65–79 zones or the host magma. Using MELTS modeling we demonstrate a significant role for H2O is not necessary to form An-rich crystals from known OJP magma types. These types of zones can instead form when relatively primitive OJP magmas ascend and partially crystallize at low pressures. Crystal mush layers are rheological elements of multiply saturated solidification fronts, and conditions for extreme fractionation are met deep with thermally and mechanically insulated mush-solidification fronts. Conditions in a homogenous magma body alone cannot generate the range of magma compositions and textures recorded in OJP plagioclase crystals. We suggest that the OJP magma chamber system consisted of crystal mush dominated regions and liquid dominated regions in a laterally and vertically extensive system of interconnected dikes and sills. Solidification front disruption was common during magma recharge and transport, which freed debris to mix with OJP magmas. The volume of crystalline debris from disrupted solidification fronts was small relative to the overall magma volume, which leads to little change of bulk magma chemistry. This can explain the dominance of the Kwaimbaita basalt type across the OJP. Evidence of solidification front disruption is best preserved as allochthonous crystals both more and less primitive than bulk magma chemistry, both of which were observed in OJP basalts. Coincident with a zone of neutral buoyancy, the shallow OJP magma chamber system existed at a depth of 0–7 km. The OJP magma chamber system was thinner near the plateau margins, which provided less density filtration of magmas. This allowed more diverse magma types to reach the surface along the margins. It is envisaged that as the OJP formed, the zone of neutral buoyancy slowly migrated upward leading to slow yet pervasive assimilation of overlying seawater-altered basalt at the base of the lava pile.

The current state of understanding of the lunar interior is the sum of nearly four decades of work and a range of exploration programs spanning that same time period. Missions of the 1960s including the Rangers, Surveyors, and Lunar Orbiters, as well as Earth-based telescopic studies, laid the groundwork for the Apollo program and provided a basic understanding of the surface, its stratigraphy, and chronology. Through a combination of remote sensing, surface exploration, and sample return, the Apollo missions provided a general picture of the lunar interior and spawned the concept of the lunar magma ocean. In particular, the discovery of anorthite clasts in the returned samples led to the view that a large portion of the Moon was initially molten, and that crystallization of this magma ocean gave rise to mafic cumulates that make up the mantle, and plagioclase flotation cumulates that make up the crust (Smith et al. 1970; Wood et al. 1970). This model is now generally accepted and is the framework that unifies our knowledge of the structure and composition of the Moon. The intention of this chapter is to review the major advances that have been made over the past decade regarding the constitution of the Moon’s interior. Much of this new knowledge is a direct result of data acquired from the successful Clementine and Lunar Prospector missions, as well as the analysis of new lunar meteorites. As will be seen, results from these studies have led to many fundamental amendments to the magma ocean model. Much of what we know from sample analyses has been previously summarized elsewhere, and only their most important aspects will be discussed in this chapter. The reader is referred to the relevant chapters in the books Basaltic Volcanism on the Terrestrial Planets (Basaltic Volcanism Study Project 1981), The …

LaPaz Icefield 02205 (LAP 02205) is a new low-Ti mare-basalt meteorite that was discovered in the LaPaz Ice Field in Antarctica. This is the first crystalline lunar basalt in the US Antarctic collection and the only 5th unbrecciated mare-basalt meteorite to be discov- ered to date. The rock has a typical basaltic texture with tabular and elongated pyroxene and plagioclase crystals, and minor olivine grains commonly rimmed by pyroxenes. Core- to rim- zoning in terms of Fe and Mg is present in almost all pyroxene grains. Accessory minerals include ilmenite, chromite, ulvospinel, troilite, and FeNi metal. This rock is highly enriched in late-stage mesostasis. Free silica is also abundant. In terms of texture and mineralogy, LAP 02205 displays features of low-Ti mare basalts, with similarities to some low- Ti Apollo 12 and Apollo 15 basalts. Whole-rock major- and trace-element compositions confirm the highly fractionated nature of this basalt. The whole-rock REE contents of the meteorite are the highest among all known low-Ti mare basalts. The platinum group element (PGE) contents in LAP are also enriched suggesting the possibility of endogenously enriched source regions or the PGEs generally behaved as incompatible elements during crystal fractionation under low fO2 conditions. Trace-element contents of mineral grains in LAP 02205 display wide variations, suggesting extensive non-equilibrium crystallization. The REE concentrations in the earliest-formed minerals provide constraints on the composition of the parental liquid, which is similar to the measured whole-rock composition. Crys- tallization modeling of the LAP 02205 bulk composition yields a reasonable fit between predicted and observed mineral phases and com- positions, except for the high-Mg olivine cores, which are observed in the rock but not predicted by the modeling. An isochron age of 2929 ± 150 Ma for phosphate minerals makes this rock one of the youngest lunar basalts known to date. The young age and specific geochemical characteristics of LAP distinguish it from those of most other low-Ti mare basalts. However, the low-Ti mare basalt mete- orite, NWA 032, has a similar young age, and the two meteorites also appear to be closely related from some geochemical perspectives and might have originated from similar source regions on the Moon.

Seventeen basalts from Ocean Drilling Program (ODP) Leg 183 to the Kerguelen Plateau (KP) were analyzed for the platinum-group elements (PGEs: Ir, Ru, Rh, Pt, and Pd), and 15 were analyzed for trace elements. Relative concentrations of the PGEs ranged from 0.1 (Ir, Ru) to 5 (Pt) times primitive mantle. These relatively high PGE abundances and fractionated patterns are not accounted for by the presence of sulfide minerals; there are only trace sulfides present in thin-section. Sulfur saturation models applied to the KP basalts suggest that the parental magmas may have never reached sulfide saturation, despite large degrees of partial melting (30%) and fractional crystallization (45%). First order approximations of the fractionation required to produce the KP basalts from an 30% partial melt of a spinel peridotite were determined using the PELE program. The model was adapted to better fit the physical and chemical observations from the KP basalts, and requires an initial crystal fractionation stage of at least 30% olivine plus Cr-spinel (49:1), followed by magma replenishment and fractional crystallization (RFC) that included clinopyroxene, plagioclase, and titanomagnetite (15:9:1). The low Pd values ((Pd/Pt)pm 1.7) for these samples are not predicted by currently available Kd values. These Pd values are lowest in samples with relatively higher degrees of alteration as indicated by petrographic observations. Positive anomalies are a function of the behavior of the PGEs; they can be reproduced by Cr-spinel, and titanomag- netite crystallization, followed by titanomagnetite resorption during the final stages of crystallization. Our modeling shows that it is difficult to reproduce the PGE abundances by either depleted upper or even primitive mantle sources. Crustal contamination, while indicated at certain sites by the isotopic compositions of the basalts, appears to have had a minimal affect on the PGEs. The PGE abundances measured in the Kerguelen Plateau basalts are best modeled by melting a primitive mantle source to which was added up to 1% of outer core material, followed by fractional crystallization of the melt produced. This reproduces both the abundances and patterns of the PGEs in the Kerguelen Plateau basalts. An alternative model for outer core PGE abundances requires only 0.3% of outer core material to be mixed into the primitive mantle source. While our results are clearly model dependent, they indicate that an outer core component may be present in the Kerguelen plume source. Copyright © 2005 Elsevier Ltd

The compositions of glass clasts in volcaniclastic rocks recovered from drilling at Site 1184 on the eastern salient of the Ontong Java Plateau (OJP) are investigated using microbeam analytical methods for major, minor and trace elements. These data are com- pared with whole-rock elemental and isotopic data for bulk tuff samples, and with data from basalts on the high plateau of the OJP. Three subunits of Hole 1184A contain blocky glass clasts, thought to represent the juvenile magmatic component of the phreatomagmatic eruptions that generated the volcaniclastic rocks. The glass clasts have unaltered centres, and are all basaltic low-K tholeiites, with flat chondrite-normalized rare earth element (REE) patterns. Their elemental compositions are very similar to the Kwaimbaita-type and Kroenke-type basalts sampled on the high plateau. Each subunit has a distinct glass com- position and there is no intermixing of glass compositions between subunits, indicating that each subunit is the result of one eruptive phase, and that the volcaniclastic sequence has not experienced reworking. The relative heterogeneity preserved at Site 1184 contrasts with the uniformity of compositions recovered from individual sites on the high plateau, and suggests that the eastern salient of the OJP had a different type of magma plumbing system. Our data support the hypothesis that the voluminous subaerially erupted volcani- clastic rocks at Site 1184 belong to the same magmatic event as the construction of the main Ontong Java Plateau. Thus, the OJP would have been responsible for volatile fluxes into the atmosphere in addition to chemical fluxes into the oceans, and these factors may have influenced the contemporaneous oceanic anoxic event.

Lunar meteorite EET 96008 is a fragmental breccia that predominantly consists of basaltic mineral clasts (0.5–2 mm), along with minor lithic fragments and breccia clasts. The matrix consists mainly of smaller mineral fragments ( The molar Fe/Mn ratio in olivines and pyroxenes and the age of the meteorite are evidence for a lunar origin. The mineralogy of EET 96008 shows close affinity to a mare-basalt source, albeit with possible minor highland/non-mare components. The bulk-rock, major-, trace- and rare-earth-element (REE) contents are similar to that of very low-titanium (VLT) basalts, which have experienced extreme fractional crystallization to the point of silicate liquid immiscibility. Mineralogical and textural features of this sample suggest that at least some of the breccia components were derived from a slow-cooled magma. The mineralogy and petrology of EET 96008 is strikingly similar to the lunar meteorite EET 87521, and we support the conclusion that EET 96008 and EET 87521 should be paired. Isochron ages of 3530 ± 270 Ma for apatite and 3519 ± 100 Ma for whitlockite of this rock are consistent with derivation from a mare-basalt precursor. These ages are within error of the low-Ti basalts, dated from the Apollo 12 and 15 sites. The whole-rock, platinum-group-element (PGE) contents of EET 96008 overlap with pristine low-Ti mare basalts, suggesting the presence of only a minimal extraterrestrial component.

The geochemical reference material BHVO-1 was analysed by a variety of techniques over a six year period. These techniques included inductively coupled plasma-mass spectrometry and atomic emission spectroscopy (ICP-MS and ICP-AES, respectively), laser ablation ICP-MS and spark source mass spectroscopy. Inconsistencies between the published consensus values reported by Gladney and Roelandts (1988, Geostandards Newsletter) and the results of our study are noted for Rb, Y, Zr, Pb and Th. The values reported here for Rb, Y, Zr and Pb are generally lower, while Th is higher than the consensus value. This is not an analytical artefact unique to the University of Notre Dame ICP-MS facility, as most of the BHVO-1 analyses reported over the last ten to twenty years are in agreement with our results. We propose new consensus values for each of these elements as follows: Rb = 9.3 ± 0.2 μg g-1 (compared to 11 ± 2 μg g-1), Y = 24.4 ± 1.3 μg g-1 (compared to 27.6 ± 1.7 μg g-1), Zr = 172 ± 10 μg g-1 (compared to 179 ± 21 μg g-1), Pb = 2.2 ± 0.2 μg g-1 (compared to 2.6 ± 0.9 μg g-1) and Th = 1.22 ± 0.02 μg g-1 (compared to 1.08 ± 0.15 μg g-1). Le materiau certifie de reference BHVO-1 a ete analyse par differentes techniques sur une periode de six annees. Ces techniques incluaient les couplages entre source plasma et spectrometrie de masse et spectroscopie d'emission (ICP-MS et ICP-AES respectivement), le couplage ICP-MS - laser et la spectroscopie de masse aetincelle. Des incoherences ont ete trouvees entre les resultats de notre etude et les donnees generalement admises reportees par Gladney et Roelandts (1988, Geostandards Newsletter), ceci pour les elements Rb, Y, Zr, Pb et Th. Nos valeurs pour Rb, Y, Zr et Pb sont en general plus basses et celles de Th b-plus elevees que les valeurs generalement admises. Ce ne peut pas etre un artefact analytique liea notre service ICP-MS puisque la majorite des valeurs publiees ces dix a vingt dernieres annees sont en accord avec les notres. Nous proposons donc les valeurs recommandees suivantes: Rb = 9.3 ± 0.2 μg g-1 (a comparer a 11 ± 2 μg g-1), Y = 24.4 ± 1.3 μg g-1 (a comparer a 27.6 ± 1.7 μg g-1), Z r = 172 ± 10 μg g-1 (a comparer a 179 ± 21 μg g-1), Pb = 2.2 ± 0.2 μg g-1 (a comparer a 2.6 ± 0.9 μg g-1) et Th = 1.22 ± 0.02 μg g-1 (a comparer a 1.08 ± 0.15 μg g-1).

Mafic granulite-facies xenoliths in alkali basalts from Chantaburi province represent the only known lower-crustal material in Thailand. Most xenoliths contain garnet (or its secondary product—kelyphite), plagioclase, and clinopyroxene, ± traces of corundum, and are grouped into garnet-rich and clinopyroxene-rich granulites (Groups 2 and 3, respectively). One sample is classified as olivine-garnet clinopyroxenite (Group 1), reflecting the presence of olivine and spinel and the absence of plagioclase. Whole-rock chemistry suggests that the protoliths of these granulite xenoliths have high normative olivine, plagioclase, and diopside, and, in most cases, low abundances and generally flat REE profiles with positive Eu anomalies. These characteristics indicate that the protoliths originated as basaltic cumulates, similar to troctolite and olivine-gabbro. On cooling, cumulate protoliths transformed to granulite-facies assemblages, mainly by the reaction: Pl + Ol = Gt + Cpx. Interestingly, some granulite xenoli...

Fractionated basalts (4.5–8.9 wt.% MgO) from the islands of Malaita and Makira (San Cristobal) in the Solomon Islands represent outpourings of magma that formed the Ontong Java Plateau (OJP), SW Pacific. The origin of the OJP is explored by examining platinum-group element (PGE: Ru, Rh, Pd, Ir, Pt) abundances in these basalts. On Makira, mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) are occasionally intercalated within the stratigraphic sequence of the OJP—the OIBtype basalts could be representative of the plume tail sequence and the MORB-type flows may be an indication of heterogeneity within the OJP source. Partial melting models indicate that the MORB-type basalts were generated from a source dominated by upper mantle material. However, they suggest that the OJP basalts and the OIB-type basalts were not generated from an exclusively upper mantle source. Our illustrative modeling shows the range of PGE compositions in these plume-generated basalts are best generated from a hybrid source that incorporates 0–0.5 wt.% of outer core material, 50% depleted upper mantle and 50–49.5% lower (primitive) mantle. D 2002 Elsevier Science B.V. All rights reserved.

We have evaluated the highly siderophile element (HSE) signatures of the martian (SNC) meteorites using new and literature data. These Ir and Os concentrations correlate with the Mg# [molar Mg/(Mg+Fe)], Cr and Ni, suggesting that olivine or chromite acts as a host for compatible siderophiles. Our analysis agrees with others who have suggested that the martian mantle has chondritic relative abundances of siderophiles. We also agree that, unlike the Sr and Nd isotopic systems, there is no evidence from Os isotopes for crustal assimilation. Comparisons of the siderophile element ratios of ALH 84001 to younger SNCs give no indication of a change in the martian siderophile element pattern over time. D 2002 Published by Elsevier Science B.V.

Dhofar 019 is a new martian meteorite found in the desert of Oman. In texture, mineralogy, and major and trace element chemistry, this meteorite is classified as a basaltic shergottite. Olivine megacrysts are set within a groundmass composed of finer grained olivine, pyroxene (pigeonite and augite), and maskelynite. Minor phases are chromite-ulvospinel, ilmenite, silica, K-rich feldspar, merrillite, chlorapatite, and pyrrhotite. Secondary phases of terrestrial origin include calcite, gypsum, celestite, Fe hydroxides, and smectite. Dhofar 019 is most similar to the Elephant Moraine (EETA) 79001 lithology A and Dar al Gani (DaG) 476/489 shergottites. The main features that distinguish Dhofar 019 from other shergottites are lack of orthopyroxene; lower Ni contents of olivine; the heaviest oxygen-isotopic bulk composition; and larger compositional ranges for olivine, maskelynite, and spinel, as well as a wide range for pyroxenes. The large compositional ranges of the minerals are indicative of relatively rapid crystallization. Modeling of olivine chemical zonations yield minimum cooling rates of 0.5-0.8 °C/h. Spinel chemistry suggests that crystallization took place under one of the most reduced conditions for martian meteorites, at an f O2 3 log units below the quartz-fayalite-magnetite (QFM) buffer. The olivine megacrysts are heterogeneously distributed in the rock. Crystal size distribution analysis suggests that they constitute a population formed under steady-state conditions of nucleation and growth, although a few grains may be cumulates. The parent melt is thought to have been derived from partial melting of a light rare earth element- and platinum group element-depleted mantle source. Shergottites, EETA79001 lithology A, DaG 476/489, and Dhofar 019, although of different ages, comprise a particular type of martian rocks. Such rocks could have formed from chemically similar source(s) and parent melt(s), with their bulk compositions affected by olivine accumulation.

Ocean Drilling Program (ODP) Leg 183 was designed to investigate the origin and evolution of the large igneous province composed of the Kerguelen Plateau and Broken Ridge. Of the eight sites drilled, basalt was recovered from seven, five on the plateau and two on Broken Ridge. We present results from four of these sites, 1136, 1138, 1141 and 1142. Although this large igneous province is interpreted as being derived from the Kerguelen mantle plume, the geochemical characteristics of basalt from some parts of the province indicate a role for continental lithosphere. The 118–119 Ma basalt flows recovered in the Southern Kerguelen Plateau (Site 1136) have a more subtle continental signature than shown by basalt at Leg 119 Site 738. A continental signature is absent in the 100–101 Ma tholeiitic basalts at Site 1138 in the Central Kerguelen Plateau (CKP); their age-corrected Nd–Sr–Pb isotopic values and incompatible element ratios are similar to those estimated for primitive mantle. These flows may represent a major mantle source in the Kerguelen starting-plume head. The 20 basalt units identified are a product of magma chamber replenishment, fractional crystallization, and resorption of crystallizing phases. The topmost unit, Unit 1, is a dacite that evolved from a basalt magma similar to those represented by Units 3–22; unlike the basalts the dacite magma was probably influenced by continental material. Middle Cretaceous (∼95 Ma) lavas of Sites 1141 and 1142 on Broken Ridge (originally part of the CKP) are alkalic, with one exception (a tholeiite at the base of Site 1142). The alkalic lavas may represent a late-stage cap or carapace of relatively low-degree partial melts that overlies a thick tholeiitic lava pile. The tholeiite and pebbles from the top of a probable talus deposit (Unit 2) at Site 1142 have geochemical signatures consistent with a minor contribution from continental material. This signature is absent in the other units from these two sites, which have ocean-island-like incompatible element ratios and age-corrected isotopic characteristics similar (but not identical) to those proposed for the post-30 Ma Kerguelen plume. These alkalic basalts may be the purest representatives of the Cretaceous plume tail composition yet found.

A data reduction method is described for determining platinum-group element (PGE) abundances by inductively coupled plasma-mass spectrometry (ICP-MS) using external calibration or the method of standard addition. Gravimetric measurement of volumes, the analysis of reference materials and the use of procedural blanks were all used to minimise systematic errors. Internal standards were used to correct for instrument drift. A linear least squares regression model was used to calculate concentrations from drift-corrected counts per second (cps). Furthermore, mathematical manipulations also contribute to the uncertainty estimates of a procedure. Typical uncertainty estimate calculations for ICP-MS data manipulations involve: (1) Carrying standard deviations from the raw cps through the data reduction or (2) calculating a standard deviation from multiple final concentration calculations. It is demonstrated that method 2 may underestimate the uncertainty estimate of the calculated data. Methods 1 and 2 do not typically include an uncertainty estimate component from a regression model. As such models contribute to the uncertainty estimates affecting the calculated data, an uncertainty estimate component from the regression must be included in any final error calculations. Confidence intervals are used to account for uncertainty estimates from the regression model. These confidence intervals are simpler to calculate than uncertainty estimates from method 1, for example. The data reduction and uncertainty estimation method described here addresses problems of reporting PGE data from an article in the literature and addresses both precision and accuracy. The method can be applied to any analytical technique where drift corrections or regression models are used. Cet article presente une methode de traitement des donnees permettant de determiner les concentrations des Elements de la Mine du Platine (PGE) analyses par ICP-MS avec calibration externe et addition de standard interne. La mesure des volumes par gravimetrie, l' analyse de materiaux de reference et de blancs de procedure ont ete utilisees pour minimiser les erreurs systematiques. Les standards internes ont ete utilises pour corriger les signaux mesures (coups par second, cps) de la derive instrumentale. De plus, les calculs mathematiques eux-memes peuvent contribuer a l' estimation de l' incertitude sur une procedure. Typiquement, un calcul des incertitudes estimees liees a l' analyse par ICP-MS repose: (1) Sur la propagation d' erreur lors de la transformation des nombres de coups bruts par seconde au resultat final; (2) Sur le calcul d' une deviation standard pour plusieurs calculs de concentrations finales. II a ete demontre que dans cette phase, on peut sous-estimer l' incertitude sur les valeurs calculees. Les methodes (1) et (2) ne prennent generalement pas en compte un coefficient d' erreur estimee donne par un modele de regression. Etant donne que de tels modeles participent aux estimations des incertitudes affectant les donnees calculees, un coefficient d' erreur estimee provenant de la regression doit etre inclus dans tout calcul d' erreur finale. Les intervalles de confiance sont utilises pour prendre en compte les incertitudes estimees du modele de regression. Ces intervalles de confiance sont plus simples a calculer que les incertitudes estimees avec la methode 1, par exemple. Le traitement des donnees et la methode d' estimation des incertitudes decrite ici posent le probleme de l' utilisation de donnees de la litterature sur les PGE et celui de leur precision et de leur justesse. La methode peut etre appliquee a toute analytique technique ou des corrections de derive et des modeles de regression sont utilises.

A gem quality zircon crystal from the Mud Tank Carbonatite, Australia, was carefully crushed, sieved, acid leached and hand-picked to produce three different zircon fractions: 1) clear and apparently free of inclusions; 2) with inclusions; 3) with inclusions and adhering alteration/matrix material. Each separate and the bulk sample was dissolved by 1) lithium metaborate fusion and 2) Parr bomb digestion utilizing 29 mol l−1 hydrofluoric (HF) and 16 mol l−1 nitric (HNO3) acids. In situ analyses were performed using laser ablation ICP-MS and demonstrate that, on the basis of REE, two types of inclusions are present: 1) those with a positive Ce anomaly and 2) those with no Ce anomaly. The former type of inclusion appears to be smaller than the latter. Analysis of the digested samples for the rare earth elements (REE) was then performed using a quadrupole ICP-MS. Comparison of the chondrite-normalized REE patterns for the different fractions gave apparent positive anomalies at Sm and Eu in the acid digestions but not in the fused samples. Zirconium has five isotopes (90Zr, 91Zr, 92Zr, 94Zr and 96Zr) and there is a strong tendency for Zr to combine with fluorine (19 F). Based on calculations and experiments, the increased levels of Sm and Eu in the acid digested samples were due to interferences of 90Zr19 F3 on 147 Sm and of 94Zr19 F3 on 151 Eu. Decreasing the ratio of HF:HNO3 did not remove these interferences, nor did post-treatment with perchloric acid. A mathematical method was developed to correct for these polyatomic interferences. Un cristal-gemme de zircon provenant de la carbonatite de Mud Tank, Australie, a ete soigneusement broye, tamise, lessivea l'acide et triea la main pour obtenir trois fractions de zircon: 1) limpide et sans inclusions apparentes; 2) avec inclusions; 3) avec inclusions et matrice/produits d'alteration. Chaque fraction separee et la roche totale ont ete dissoutes par 1) une fusion avec metaborate de lithium et 2) une attaque acide en bombe de Parr avec HF 29 mol l−1 et HNO3 16 mol l−1. Des analyses in situ ont ete realisees par ICP-MS avec ablation laser et mettent en evidence, du point de vue des Terres Rares, deux types d'inclusions: 1) avec une anomalie positive en Ce et 2) sans anomalie en Ce. Le premier type d'inclusions semble plus petit que le second. L'analyse des Terres Rares des echantillons issus de l'attaque acide a ete realisee par ICP-MS a quadrupole. La comparaison des spectres de Terres Rares normalises aux chondrites des differentes fractions montre des anomalies positives apparentes en Sm et Eu seulement pour les attaques acides. Le zirconium a cinq isotopes (90Zr, 91Zr, 92Zr, 94Zr et 96Zr) et une forte tendance a se combiner au fluor (19 F). A partir de calculs et d'experimentations, l'enrichissement en Sm et en Eu des echantillons issus de l'attaque acide serait du aux interferences 90Zr19 F3 sur 147 Sm et 94Zr19 F3 sur 151 Eu. La diminution du rapport HF/HNO3 ne supprime pas ces interferences, pas plus qu'un traitement final a l'acide perchlorique. Une methode mathematique a ete developpee pour corriger ces interferences polyatomiques.

New trace element data have been generated by inductively coupled plasma-mass spectrometry (ICP-MS) for 65 high- and low-Ti mare basalts from the Apollo 11, 12, 14, 15, and 17 landing sites. These data demonstrate that ratios of the high field strength elements and yttrium are generally chondritic in the mare source regions for the low-Ti basalts but nonchondritic in the high-Ti basalts and potassium, rare earth elements, and phosphorus (KREEP); such differences can be explained by addition and subtraction (respectively) of ilmenite. This interpretation is consistent with derivation of the basalts from lunar magma ocean (LMO) cumulates through which late stage ilmenite has sunk and mixed with earlier magma ocean products. Compositional differences between the mare basalts and volcanic glass beads suggest that at least some of the latter were derived from a garnet-bearing source region. Siderophile and chalcophile element data suggest that the garnet-bearing source escaped the LMO melting event and thus represents primitive Moon material. The remaining glasses are generally very low Ti (VLT) and appear to have been derived from early LMO cumulates (i.e., olivine and orthopyroxene, similar to the VLT basalts). The remaining glasses were derived from below the LMO cumulates, and as the magmas rose they underwent sequential assimilation (to varying degrees) initially of an ilmenite-rich cumulate followed by a KREEP component. This study presents geochemical evidence for the existence of garnet in a mare source and demonstrates the likelihood that the LMO was not “whole Moon,” thus preserving primitive lunar material, which has acted as the source region for at least some of the volcanic glasses.

Automobile catalytic converters are dispersing platinum-group elements (PGEs) Rh, Pt, and Pd into the environment (1-3). This paper represents the first detailed study to assess the PGE content of soils and grasses from U.S. roadsides. These soils were analyzed using cation exchange pretreatment and ultrasonic nebulizer-ICP-MS (4). Highway and several urban sites showed Pt abundances of 64-73 ng/g immediately adjacent to the roadside, with corresponding Pd and Rh abundances of 18-31 ng/g and 3-7 ng/g, respectively. All Pt and most Pd and Rh abundances are statistically above local background soil values. Platinum, Rd, and Rh show positive correlations with traffic-related elements (Ni, Cu, Zn, and Pb) but no correlations with nontraffic-related elements (Y, Ga). Iridium and Ru show no correlations with any of these trace elements. These PGE abundances are comparable to European studies (5-7) and are approaching concentrations that would be economically viable to recover. This study also demonstrates transport of Pt statistically above background more than 50 m from the roadside. Further study is necessary to see how mobile the PGEs are in roadside environments, but these initial data indicate only Pt is taken up by plants.