neoKREEP: A new lunar component at Apollo 17

The Apollo 11 (Mare Tranquillitatis) and Apollo 17 (Mare Serenitatis) landing sites are important as the only sources of high-Ti basalt visited by the Apollo missions. The lunar high-Ti basalts (greater than 6 percent TiO2) have no volumetrically comparable analogs among terrestrial basalts and require the presence of ilmenite in the source region, probably representing cumulates produced late in the crystallization of the lunar magma ocean. Six principal groups of high-Ti basalts are described, three from each of the two sites

Searching for neuKREEP: An EMP study of Apollo 11 Group A basalts

The Apollo 11 and 17 landing sites are characterized by the presence of high-Ti basalts (TiO2 greater than 6 percent). The Group A basalts of Apollo 11 have elevated K compositions (greater than 2000 ppm); and are enriched in incompatible trace elements relative to the other types of high-Ti basalt found in the region. These unique basalts also are the youngest of all high-Ti basalts, with an age of 3.56 +/- 0.02 Ga. Recent modelling of the Apollo 11 Group A basalts by Jerde et al. has demonstrated that this unique variety of high-Ti basalt may have formed through fractionation of a liquid with the composition of the Apollo 11 orange glass, coupled with assimilation of evolved material (dubbed neuKREEP and having similarities to lunar quartz monzodiorite). Assimilation of this material would impart its REE signature on the liquid, resulting in the elevated REE abundances observed. Minerals such as whitlockite which contain a large portion of the REE budget can be expected to reflect the REE characteristics of the assimilant. To this end, an examination of the whitlockite present in the Apollo 11 Group A basalts was undertaken to search for evidence of the neuKREEP material assimilated

On the composition of neuKREEP: QMD contamination at Apollo 11?

The Group A basalts of Apollo 11 differ in many respects from other high-Ti basalts of the region. Chemically, they are the only high-K (greater than 2000 ppm K) variety of high-Ti basalt and are enriched in incompatible trace elements relative to other basalts from both the Apollo 11 and Apollo 17 sites. In addition, Group A basalts are the youngest of all high-Ti basalts, with an age of 3.56 +/- 0.02 Ga. The cluster of compositions is consistent with the Apollo 11 Group A basalts representing a single flow. Papanastassiou et al. have also indicated the uniqueness of these basalts, based particularly on relatively young Rb-Sr model ages (3.8 - 3.9 Ga). A model for the formation of the Group A basalts was presented by Jerde et al., wherein the Apollo 17 orange volcanic glass is the parent liquid. Fractionation of this composition, coupled with the assimilation of incompatible-element-rich material, results in compositions akin to those of the Apollo 11 Group A basalt population. Orange glass of similar major-element composition is present at the Apollo 11 site as well, although complete trace element analyses are not available. New modelling results using the Apollo 11 orange glass major elements are grossly similar to those obtained using the Apollo 17 orange glass, indicating approximately 30 percent fractionation

Evolution of the upper mantle of the Earth's Moon: Neodymium and strontium isotopic constraints from high-Ti mare basalts

Isotopic studies of mare basalts have led workers to conclude that their sources are heterogeneous on both large and small scales. Furthermore, these studies have led workers to postulate that depletion within the lunar mantle occurred early in its evolution and was a result of accumulation of mafic minerals from a LREE-enriched magma ocean. High-Ti basalts from the Apollo 11 and 17 landing sites and ilmenite basalts from Apollo 12 are secondary evidence of this extreme, early depletion event. KREEPy rocks are the complementary enriched component in the Moon.A total of fourteen high-Ti basalts have now been analyzed from the Apollo 11 landing site for neodymium and strontium isotopes. A Sm-Nd internal isochron on basalt 10058 yields an age of 3.70 +/- 0.06 Ga, similar to 40Ar/39Ar ages of other Group B1 basalts. A compilation of all previously determined ages on Apollo 11 high-Ti basalts indicates four distinct phases of volcanism at 3.85 +/- 0.02 Ga (Group B2), 3.71 +/- 0.02 Ga (Group B3), 3.67 +/- 0.02 Ga (Group B1), and 3.59 +/- 0.04 Ga (Group A). Wholerock Sm-Nd isotopic data for all Apollo 11 high-Ti basalts form a linear array, which yields the age of the Moon (4.55 +/- 0.30 Ga). A similar regression of all uncontaminated high-Ti basalts from the Moon (both Apollo 11 and Apollo 17) yields an age of 4.46 +/- 0.17 Ga. Both arrays are interpreted as average source ages of the high-Ti basalts and are consistent with the formation of these sources by precipitation of cumulates from a magma ocean early in the history of the Moon.These new strontium and neodymium isotopic data, coupled with previously published data, are consistent with a two component model for the upper mantle of the Moon. These two-components include mafic adcumulates precipitated from a magma ocean prior to 4.4 Ga and small amounts (147Sm/144Nd = 0.318 and 87Rb/86Sr = 0.005 to extremely radiogenic neodymium isotopic ratios and very unradiogenic strontium isotopic ratios. The KREEPy trapped liquid has a 147Sm/144Nd = 0.168 and 87Rb/86Sr = 0.235 and thus, evolves toward very unradiogenic neodymium and radiogenic strontium isotopic ratios. Because the KREEPy trapped liquid is enriched in both rubidium and the REEs by over an order of magnitude compared to the mafic adcumulate, trapping of even small proportions of this liquid in the adcumulate will control the radiogenic isotopic composition of the source. The apparent heterogeneity in the source regions of mare basalts could be caused by trapping of variable, yet small, proportions of this LILE-enriched liquid in the cumulate pile.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31245/1/0000151.pd

Nd and Sr isotopes from diamondiferous eclogites, Udachnaya Kimberlite Pipe, Yakutia, Siberia: Evidence of differentiation in the early Earth?

Nd and Sr isotopic data from diamond-bearing eclogites found in the Udachnaya kimberlite, Yakutia, Siberia, are interpreted as indicating an early ([ges] 4 Ga) differentiation event, whereby the mantle split into complementary depleted and enriched reservoirs. Reconstructed whole-rock 87Sr/86Sr ratios (present-day) range from 0.70151 to 0.70315 and are consistent with a mantle origin for these rocks. The Nd isotopic evolution lines of four samples (U-5, U-37, U-41 and U-79) converge at 2.2-2.7 Ga. Sample U-5 is unique in exhibiting the most enriched signature of any of the samples yet analyzed (present-day [epsilon]Nd of -20), and this sample points unequivocally to an old, enriched component. A complementary depleted mantle component is suggested by two of the eclogite samples, U-86 and U-25, which yield [epsilon]Nd values (at 2.2 Ga) of + 13 and + 7, respectively. The two mantle reservoirs possibly formed prior to 4 Ga and evolved separately until 2.2-2.7 Ga. At that time, the reservoirs were melted forming eclogites both as residues (from the enriched reservoir) and as partial melts of peridotite (from the depleted reservoir), resulting in demonstrably different histories for eclogites from the same locality.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30700/1/0000345.pd

Archean mantle heterogeneity and the origin of diamondiferous eclogites, Siberia: Evidence from stable isotopes and hydroxyl in garnet

Data are presented for the O isotopic composition of clinopyroxene and garnet, the C isotopic composition of diamond, and the OH- content of garnet from eclogite xenoliths brought to the surface by the Udachnaya kimberlite pipe, Yakutia, Siberia. Radiogenic isotopic data suggest that the eclogites could have been derived from an ultradepleted mantle at approximately 2.9 Ga (Pearson et al., 1995; Snyder et al., in preparation). O isotopic compositions generally show equilibration between the eclogitic minerals (Δ_(cpx-Grt) = 0.11-0.41‰) and have δ^(18)O_(SMOW) for both garnet and clinopyroxene that lie near the range of accepted mantle values of 5.7±0.7‰. However, several eclogites indicate significant deviations from this range, at higher values of 6.8-7.0‰. Also, two eclogites lie at the lower end of the mantle range, at values of 4.8 and 5.0‰ (all in clinopyroxene). C isotopic compositions of diamonds all have δ^(13)C_(PDB) in the range of -1 to -7‰ and are centered at approximately -5‰, also within the range of accepted mantle values. The OH- contents of the garnet are generally between 0 and 22 ppm (as H_(2)0), although two samples exceed 70 ppm. This range of OH- is similar to eclogitic garnet from the Kaapvaal craton of southern Africa. The mantle C isotopic values of associated diamonds, the majority of O isotopic data, and the low OH- content of the minerals, although suggesting a general lack of crustal participation in the formation of the Udachnaya eclogites, do not rule out the participation of some ancient crustal material. That these eclogites include both ^(18)O-enriched and ^(18)O-depleted types suggests that the protoliths may have been overprinted by both low- and high-temperature hydrothermal events (cf. Jacob et aI., 1994). A positive correlation between δ^(18)O and ^(87)Sr/^(86)Sr allows the interpretation of these eclogites as representing a cross section of an Archean ophiolite. However, the lack of a single coherent grouping on a plot of δ^(18)O vs. ^(87)Sr/^(86)Sr suggests that, if the Udachnaya eclogites were derived from oceanic crust, they cannot be cogenetic and must represent at least two separate ophiolite sequences. Conversely, if the eclogites are found to be cogenetic, then a totally different process affected their formation and a probable metasomatic mechanism was operative. Because of the total lack of correlation of δ^(18)O with other geochemical parameters, we find no compelling evidence that all eclogites are derived ultimately from oceanic crust

Critical considerations for communicating environmental DNA science

Abstract The economic and methodological efficiencies of environmental DNA (eDNA) based survey approaches provide an unprecedented opportunity to assess and monitor aquatic environments. However, instances of inadequate communication from the scientific community about confidence levels, knowledge gaps, reliability, and appropriate parameters of eDNA‐based methods have hindered their uptake in environmental monitoring programs and, in some cases, has created misperceptions or doubts in the management community. To help remedy this situation, scientists convened a session at the Second National Marine eDNA Workshop to discuss strategies for improving communications with managers. These include articulating the readiness of different eDNA applications, highlighting the strengths and limitations of eDNA tools for various applications or use cases, communicating uncertainties associated with specified uses transparently, and avoiding the exaggeration of exploratory and preliminary findings. Several key messages regarding implementation, limitations, and relationship to existing methods were prioritized. To be inclusive of the diverse managers, practitioners, and researchers, we and the other workshop participants propose the development of communication workflow plans, using RACI (Responsible, Accountable, Consulted, Informed) charts to clarify the roles of all pertinent individuals and parties and to minimize the chance for miscommunications. We also propose developing decision support tools such as Structured Decision‐Making (SDM) to help balance the benefits of eDNA sampling with the inherent uncertainty, and developing an eDNA readiness scale to articulate the technological readiness of eDNA approaches for specific applications. These strategies will increase clarity and consistency regarding our understanding of the utility of eDNA‐based methods, improve transparency, foster a common vision for confidently applying eDNA approaches, and enhance their benefit to the monitoring and assessment community

Risk Analysis and Bioeconomics of Invasive Species to Inform Policy and Management

Risk analysis of species invasions links biology and economics, is increasingly mandated by international and national policies, and enables improved management of invasive species. Biological invasions proceed through a series of transition probabilities (i.e., introduction, establishment, spread, and impact), and each of these presents opportunities for management. Recent research advances have improved estimates of probability and associated uncertainty. Improvements have come from species-specific trait-based risk assessments (of estimates of introduction, establishment, spread, and impact probabilities, especially from pathways of commerce in living organisms), spatially explicit dispersal models (introduction and spread, especially from transportation pathways), and species distribution models (establishment, spread, and impact). Results of these forecasting models combined with improved and cheaper surveillance technologies and practices [e.g., environmental DNA (eDNA), drones, citizen science] enable more efficient management by focusing surveillance, prevention, eradication, and control efforts on the highest-risk species and locations. Bioeconomic models account for the interacting dynamics within and between ecological and economic systems, and allow decision makers to better understand the financial consequences of alternative management strategies. In general, recent research advances demonstrate that prevention is the policy with the greatest long-term net benefit

Toward a national eDNA strategy for the United States

Abstract Environmental DNA (eDNA) data make it possible to measure and monitor biodiversity at unprecedented resolution and scale. As use‐cases multiply and scientific consensus grows regarding the value of eDNA analysis, public agencies have an opportunity to decide how and where eDNA data fit into their mandates. Within the United States, many federal and state agencies are individually using eDNA data in various applications and developing relevant scientific expertise. A national strategy for eDNA implementation would capitalize on recent scientific developments, providing a common set of next‐generation tools for natural resource management and public health protection. Such a strategy would avoid patchwork and possibly inconsistent guidelines in different agencies, smoothing the way for efficient uptake of eDNA data in management. Because eDNA analysis is already in widespread use in both ocean and freshwater settings, we focus here on applications in these environments. However, we foresee the broad adoption of eDNA analysis to meet many resource management issues across the nation because the same tools have immediate terrestrial and aerial applications