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Silicate-bearing iron meteorites record metal–silicate separation and mixing processes of planetesimals. Of particular interest is the IIE group as its silicate inclusions show great petrological diversity, probably resulting from the complex petrogenesis involving early differentiation and impact-induced dynamic mixing, re-melting, and reduction. These geologic records may have been documented by individual minerals to various extents, which blurs the chronological records on the formation of IIEs. Here, by combining X-ray elemental mapping with ion microprobe dating technique, we show that two groups of phosphates are present in the Weekeroo Station IIE iron meteorite. They have distinct petrography, mineralogy, Th/U ratios, and Pb isotopic compositions, which reflects their different formation mechanisms. One group (Group 1) has a fine-grained, euhedral or acicular habit, suggesting rapid crystallization from a melt during the metal–silicate mixing. By contrast, the other group (Group 2) is intimately associated with the decomposition and reduction of pyroxene under subsolidus conditions. The Group 1 phosphates yield a precise Pb–Pb age of 4528 ± 11 Ma and they provide the first robust constraint on the timing of impact-induced metal–silicate mixing on the IIE iron meteorite parent body. The Group 2 phosphates, on the other hand, probably record a Pb–Pb age at least 50 Myr younger, and they give insight into the role of subsequent impacts on the alteration of IIE irons. Combining our results with published chronological data suggests that the formation of IIEs irons is consistent with early partial differentiation followed by multiple impact-driven metal–silicate mixing and that most of them were not shielded from subsequent impacts.

Impact glasses found in lunar soils provide a possible window into the impact history of the inner solar system. However, their use for precise reconstruction of this history is limited by an incomplete understanding of the physical mechanisms responsible for their origin and distribution and possible relationships to local and regional geology. Here, we report U-Pb isotopic dates and chemical compositions of impact glasses from the Chang’e-5 soil and quantitative models of impact melt formation and ejection that account for the compositions of these glasses. The predominantly local provenance indicated by their compositions, which constrains transport distances to

LA-ICP-MS method was applied to investigate U-Pb and Lu-Hf isotope systematics of zircon crystals from charnockitic gneiss and biotite-garnet-hypersthene enderbite that occur in the lower reaches of the Yatran river (Yatran block of the Bouh river area). According to the obtained isotope data, charnockitic gneiss hosts three zircon populations. The oldest one is represented by three crystals that have isotope age between 3125 and 3300 Ma, and εHf values between –2.3 and –7.5. The next population is well-defined, it has an age of 2038±25 Ma and large variations of Hf isotope composition: 176Hf/177Hf — from 0.28122 to 0.28261, εHf — from –9.3 до 4.6. However, the ages of most of the analyzed zircons spread along the concordia between 2300 and 2800 Ma. All zircons in this population have a similar Hf isotope composition 176Hf/177Hf = 0.28072 to 0.28092, which does not depend on the age. It is characteristic that the oldest (with preserved U-Pb isotope systematics) crystals have positive or slightly negative εHf values. Most of the U-Pb isotope analyses of zircons from enderbite fall on the discordia line that has an upper interception age of 2029 ± 18 Ma. A small number of discordant grains have 207Pb/206Pb ages up to 2500 Ma. Hafnium isotope composition in zircons from enderbite varies widely: 176Hf/177Hf = 0.28131 to 0.28151, and εHf from –6.2 to 1.8.

Apollo 16 soil-like regolith breccia 65745,7 contains two zircon-bearing clasts. One of these clasts is a thermally annealed silica-rich rock, which mineralogically has affinities with the High Alkali Suite (Clast 1), and yields zircon dates ranging from 4.08 to 3.38 Ga. The other clast is a KREEP-rich impact melt breccia (Clast 2) and yields zircon dates ranging from 3.97 to 3.91 Ga. The crystalline cores of both grains, which yield dates ofca3.9 Ga, have undergone shock pressure modification at less than 20 GPa. We interpret that the U-Pb chronometer in these zircon grains has been partially reset by the Imbrium basin-forming event when the clasts were incorporated into the Cayley Plains ejecta blanket deposit. The zircon grains in Clast 1 have been partially decomposed, resulting in a breakdown polymineralic texture, with elevated U, Pb and Th abundances compared with those in the crystalline zircon. These decomposed areas exhibit younger dates around 3.4 Ga, suggesting a secondary high-pressure, high-temperature event, probably caused by an impact in the local Apollo 16 highlands area.

The triple oxygen isotope compositions of phosphate grains in six martian meteorites have been measured by Secondary Ion Mass Spectrometry (SIMS) and combined together with their chlorine isotope and halogen concentrations have been used to constrain hydrosphere-lithosphere interactions on Mars. These samples include three enriched shergottites (Zagami, Roberts Massif 04262 and Larkman Nunatak 12011), one depleted shergottite (Tissint), an orthopyroxenite (Allan Hills 84001), and a regolith breccia (Northwest Africa 7533). The phosphates measured here have a range in δ18O [(18O/16O)sample/(18O/16O)Standard-1] × 103] from +1.0 to +6.8‰ and could be a result of indigenous mantle values, mixing with martian water, or replacement reactions taking place on the surface of Mars. Three samples have a Δ17O [δ17O-1000(1 + δ18O /1000)0.528-1] in equilibrium with the martian mantle (ALH 84001, Tissint, and Zagami), while three samples (LAR 12011, RBT 04262, and NWA 7533) have an elevated positive Δ17O outside of analytical uncertainty of the martian fractionation line (MFL). The phosphates in the latter group also have positive and negative δ37Cl [(37Cl/35Cl)sample/(37Cl/35Cl)standard – 1] × 103] and enrichments in halogens not seen in the rest of the sample suite. Perchlorate formation on Earth fractionates Cl in both positive and negative directions and generates a correlated positive Δ17O. Further, perchlorate has been detected in wt% amounts on the martian surface. Thus, these results strongly suggest the presence of multiple Cl isotope reservoirs on the martian surface that have interacted with the samples studied here over the last ca. 2 Ga of geologic time. The weighted average of Δ17O measurements from phosphate grains (n = 13) in NWA 7533, which are the explicit result of exchange reactions on the martian surface, yields a statistically robust mean value of 1.39 ± 0.19‰ (2σ, MSWD = 1.5, p = 0.13). This value likely represents an accurate estimate for an oxidized surface reservoir on Mars.

The LA-ICP-MS method was applied to investigate U-Pb and Lu-Hf isotope systematics of zircon crystals from charnockitoids that crop out in the open pits near Chausove village, Pervomaisk district. The association of enderbite gneisses, mafic and ultramafic (pyroxenite) granulites and vein bodies of pink biotite granites occur in the open pits. Enderbites are rather heterogeneous, and their composition varies from leucocratic quartzite-like rocks to enderbite-diorite. The Pervomaisk open pit is located within charnockite massif. Our data indicates that the association of enderbites and charnockites crystallised at 2850-2760 Ma from juvenile material (Hf isotope composition in zircons from enderbite-diorite is 176Hf/177Hf = 0.280915 ± 12, εHf2850 = +2; from leucocratic charnockite 176Hf/177Hf = 0.280875 ± 12, εHf2760 = –1; and from charnockite 176Hf/177Hf = 0.280875 ± 12, εHf2760 = –1). These rocks represented the newly formed Meso-Neoarchean crust, in contrast to the reworked older continental crust. This association has experienced a significant transformation in Paleoproterozoic. The last stage of transformation was accompanied by crystallisation of a new generation of zircon and formation of monazite at 2.04-2.06 Ga.

Significance We discovered a zircon record in a Martian meteorite that spans 4.2 Gyr, nearly the entire geologic history of Mars. Ancient zircons define a bimodal distribution with groupings at 4474 ± 10 Ma and 4442 ± 17 Ma, reflecting intense bombardment episodes triggered by the migration of the gas giant planets. A group of younger detrital zircons record ages from 1548.0 ± 8.8 Ma to 299.5 ± 0.6 Ma. The only plausible sources for these grains are the Elysium and Tharsis volcanic provinces that are the expressions of deep-seated mantle plumes. The chondritic-like Hf-isotope compositions of these zircons require the existence of a primitive and convecting mantle reservoir. Thus, these grains provide a tangible record of the deep Martian interior., Combining U–Pb ages with Lu–Hf data in zircon provides insights into the magmatic history of rocky planets. The Northwest Africa (NWA) 7034/7533 meteorites are samples of the southern highlands of Mars containing zircon with ages as old as 4476.3 ± 0.9 Ma, interpreted to reflect reworking of the primordial Martian crust by impacts. We extracted a statistically significant zircon population (n = 57) from NWA 7533 that defines a temporal record spanning 4.2 Gyr. Ancient zircons record ages from 4485.5 ± 2.2 Ma to 4331.0 ± 1.4 Ma, defining a bimodal distribution with groupings at 4474 ± 10 Ma and 4442 ± 17 Ma. We interpret these to represent intense bombardment episodes at the planet’s surface, possibly triggered by the early migration of gas giant planets. The unradiogenic initial Hf-isotope composition of these zircons establishes that Mars’s igneous activity prior to ∼4.3 Ga was limited to impact-related reworking of a chemically enriched, primordial crust. A group of younger detrital zircons record ages from 1548.0 ± 8.8 Ma to 299.5 ± 0.6 Ma. The only plausible sources for these grains are the temporally associated Elysium and Tharsis volcanic provinces that are the expressions of deep-seated mantle plumes. The chondritic-like Hf-isotope compositions of these zircons require the existence of a primitive and convecting mantle reservoir, indicating that Mars has been in a stagnant-lid tectonic regime for most of its history. Our results imply that zircon is ubiquitous on the Martian surface, providing a faithful record of the planet’s magmatic history.

The lunar cratering record is used to constrain the bombardment history of both the Earth and the Moon. However, it is suggested from different perspectives, including impact crater dating, asteroid dynamics, lunar samples, impact basin-forming simulations, and lunar evolution modelling, that the Moon could be missing evidence of its earliest cratering record. Here we report that impact basins formed during the lunar magma ocean solidification should have produced different crater morphologies in comparison to later epochs. A low viscosity layer, mimicking a melt layer, between the crust and mantle could cause the entire impact basin size range to be susceptible to immediate and extreme crustal relaxation forming almost unidentifiable topographic and crustal thickness signatures. Lunar basins formed while the lunar magma ocean was still solidifying may escape detection, which is agreeing with studies that suggest a higher impact flux than previously thought in the earliest epoch of Earth-Moon evolution., Lunar impact basins formed during the magma ocean solidification should have formed almost unidentifiable topographic and crustal thickness signatures, thus may escape detection. This result allows for a higher impact flux in the earliest epoch of Earth-Moon evolution.

The limited preservation of ancient crustal material poses a challenge for understanding the composition of Earth’s early crust. As a result of poor preservation and near-ubiquitous overprinting by later geological events, deciphering the early evolution of our planet often relies on the isotopic composition of resistive minerals, such as zircon. Although the isotopic information recorded by zircon grains has proved an invaluable asset to workers seeking to understand the geological evolution of the Earth, it is limited by the range of elements easily incorporated into the structure of the mineral. One way to overcome these limitations is by analysing inclusions of other minerals that were trapped within the zircon during crystallisation. Apatite has great potential in this respect, as it is commonly found as inclusions in magmatic zircon and records a variety of useful isotopic information. Here we present an approach for investigating igneous petrogenesis and crustal evolution by combining 87Sr/86Sr measurements of apatite inclusions with U–Pb and Hf isotope analysis of their host zircon crystal. The Sr isotope information contained in the apatite can be accessed by applying a novel SIMS technique we developed for this purpose. A case study applying this new approach to Eoarchean igneous rocks of the Narryer Terrane in the northern Yilgarn Craton of Western Australia demonstrates how this can be used to understand the evolution of this key locality, with implications for both regional geology and the growth of the continental crust.

Glass beads formed by ejection of impact-melted lunar rocks and soils are an important component of lunar soils. These glasses range from 100s of microns to up to a few cm in diameter and contain variable, but usually relatively low (several hundred ppb to a few ppm), quantities of U. Because Pb is a volatile element, it tends to be lost from the melts, so individual impact glasses can be dated by the U-Th-Pb isotopic systems. The presence of two additional Pb components in lunar glasses, likely linked to addition of lunar Pb to the beads during their residence on the lunar surface and from terrestrial laboratory contamination, require corrections to the data before accurate formation ages of the glasses can be determined. Here we report a U-Th-Pb isotopic and geochemical study of impact glasses from the Apollo 14 soil 14163, which documents multiple impacts into chemically diverse targets that can be linked to the main groups of rocks found on the Moon, i.e., mare basalts, highlands plagioclase-rich rocks, and KREEP (from high contents of K, REE and P) enriched rocks. The impact ages show a bimodal distribution with peaks at ~3500-3700 Ma and < 1000 Ma, similar to that obtained previously by Ar-40-Ar-39 dating of other suites of lunar regolith glasses. Our data suggest two predominant age peaks at ~100 Ma and ~500 Ma, with other statistically definable clusters of ages also possible. As Pb is relatively resistant to subsolidus diffusive loss in these glasses, the age clusters probably represent primary formation ages during impact events, although processes such as preferential preservation of young glasses and impact conditions necessary for production of regolith glasses need further quantification. (C) 2021 The Authors. Published by Elsevier Ltd.

Funding: TEJ acknowledges support from the State Key Laboratory for Geological Processes and Mineral Resources, China University of Geosciences, Wuhan (Open Fund GPMR201903 ). We thank J. B. Balta and T. Prissel for their challenging reviews that led to significant improvements in the final version. Despite some 50 years of intense research on samples returned from the Apollo missions and lunar meteorites, along with remote-sensing and Earth-based observations, many questions regarding the formation and evolution of the Moon persist. These include the detailed compositional and density structure of the lunar mantle and the source and petrogenesis of the diverse suite of extrusive and intrusive igneous rocks. There is broad agreement that the primary internal structure of the Moon reflects crystallisation of a lunar magma ocean (LMO), and that an inverted density gradient within the mantle cumulates led to some reorganisation of layers by partial convective overturn. Experimental studies have provided invaluable constraints on crystallisation of the LMO, but are limited by the relatively small number of experiments that can practically be undertaken. Here we use recently-developed thermodynamic models for minerals and melt in the K2O–Na2O–CaO–FeO–MgO–Al2O3–SiO2–TiO2–Cr2O3 system to model crystallisation of a full-moon LMO based on two existing end-member bulk compositions—Taylor Whole-Moon (TWM), and Lunar Primitive Upper Mantle, LPUM—on which many experimental studies have been based. We follow several recent studies in considering equilibrium crystallisation of the first 50 vol.% and fractional crystallisation thereafter. Our results match well with experimental studies, and provide detailed constraints on the major oxide composition, mineralogy and density structure based on the two starting compositions that, while exhibiting some similarities, show important differences. The more fertile TWM composition contains significant quantities of garnet in the deep mantle, whereas the LPUM composition has none. By contrast, prior to any gravitational overturn, the uppermost mantle cumulates for TWM are strongly silica-undersaturated and contain abundant aluminous spinel, whereas those for LPUM are silica-saturated. For both starting compositions, with the exception of TiO2 and Na2O, our modelled compositions of the final dregs of fractionated melt show a reasonable match with existing estimates on the composition of urKREEP. Modelled partial melts of the upper-mantle cumulates at low to moderate melt fractions have major oxide compositions that match well with low- and intermediate-Ti lunar basalts. The correspondence is particularly good for picritic (green) glasses that likely represent melts derived from deeper levels within the upper mantle. The wide spread in TiO2 concentrations in lunar basalts and basaltic glasses is consistent with density-driven reorganisation involving ilmenite. Our simulations provide thermodynamically-robust estimates of the compositional, mineralogical and density structure of the lunar interior that are unprecedented in their detail, and which provide the foundation for several lines of future research addressing the origin and secular evolution of the Moon. Postprint

Sample return shows late lunar volcanism Measuring physical samples of Solar System bodies in the laboratory provides more information than is possible from remote sensing alone. In December 2020, the Chang’e-5 mission landed on the Moon, collected samples, and returned them to Earth. Che et al . analyze two fragments of volcanic lunar basalt collected by Chang’e-5. Radiometric dating using lead isotopes indicated that the rocks formed from magma that erupted about 2 billion years ago, later than other volcanic lunar samples. The abundance of extinct radioactive elements in the rock is too low for radioactive heating to have produced the magma. Another, thus far unknown, source must be responsible for the late lunar volcanism. —KTS

Orbital data indicate that the youngest volcanic units on the Moon are basalt lavas in Oceanus Procellarum, a region with high levels of the heat-producing elements potassium, thorium, and uranium. The Chang’e-5 mission collected samples of these young lunar basalts and returned them to Earth for laboratory analysis. We measure an age of 1963 ± 57 Ma for these lavas and determine their chemical and mineralogical compositions. This age constrains the lunar impact chronology of the inner Solar System and the thermal evolution of the Moon. There is no evidence for high concentrations of heat-producing elements in the deep mantle of the Moon that generated these lavas, so alternate explanations are required for the longevity of lunar magmatism.

The results of an LA-ICP-MS U-Pb dating and Hf isotope study of zircon crystals separated from small eclogite xenoliths found in Devonian kimberlites within the Prypyat horst, Ukraine, are reported. The studied area is located in the Central Belarusian Suture Zone, which represents a Paleoproterozoic belt extending along the boundary between the Sarmatian and Fennoscandian segments of the East European Platform. Four laser ablation sites on two zircon grains yielded Paleoproterozoic U-Pb ages between 1954 ± 24 Ma and 1735 ± 54 Ma. In contrast, three of four Hf sites revealed negative εHf values and Paleoarchean to Mesoarchean model ages, excluding the possibility that the eclogite xenoliths represent segments of a Paleoproterozoic subducted slab or younger mafic melts crystallized in the subcontinental lithospheric mantle. A single laser ablation Hf spot yielded a positive εHf value (+3) and a Paleoproterozoic model age. Two models for eclogite origin can be proposed. The first foresees the extension of the Archean lower-crustal or lithospheric roots beneath the Central Belarus Suture Zone for over 200 km from the nearest known outcrop of Archean rocks. The second model is that the Central Belarus Suture Zone represents a rifted-out fragment of the Kola-Karelian craton that was accreted to Sarmatia before the actual collision of these two segments of Baltica.

Precise crystallisation ages have been determined for a range of Apollo basalts from Pb-Pb isochrons generated using Secondary Ion Mass Spectrometry (SIMS) analyses of multiple accessory phases including K-feldspar, K-rich glass and phosphates. The samples analysed in this study include five Apollo 11 high-Ti basalts, one Apollo 14 high-Al basalt, seven Apollo 15 low-Ti basalts, and five Apollo 17 high-Ti basalts. Together with the samples analysed in two previous similar studies, Pb-Pb isochron ages have been determined for all of the major basaltic suites sampled during the Apollo missions. The accuracy of these ages has been assessed as part of a thorough review of existing age determinations for Apollo basalts, which reveals a good agreement with previous studies of the same samples, as well as with average ages that have been calculated for the emplacement of the different basaltic suites at the Apollo landing sites. Furthermore, the precision of the new age determinations helps to resolve distinctions between the ages of different basaltic suites in more detail than was previously possible. The proposed ages for the basaltic surface flows at the Apollo landing sites have been reviewed in light of these new sample ages. Finally, the data presented here have also been used to constrain the initial Pb isotopic compositions of the mare basalts, which indicate a significant degree of heterogeneity in the lunar mantle source regions, even among the basalts collected at individual landing sites.

U-Pb ages of zircon in four different Apollo 14 breccias (14305, 14306, 14314, and 14321) were obtained by secondary ion mass spectrometry. Some of the analyzed grains occur as cogenetic, poikilitic zircon grains in lithic clasts, revealing magmatic events at ~4286 Ma, ~4200–4220 Ma, and ~4150 Ma. The age distribution of the crystal clasts in the breccias exhibits a minor peak at ~4210 Ma, which can be attributed to a magmatic event, as recorded in zircon grains located in noritic clasts. An age peak at ~4335 Ma is present in all four breccias, as well as zircon grains from different Apollo landing sites, enhancing the confidence that these grains recorded a global zircon-forming event. The overall age distribution among the four breccias exhibits minor differences between the breccias collected farther away from the Cone Crater and the ones collected within the continuous ejecta blanket of the Cone Crater. A granular zircon grain yielded a 207Pb/206Pb age of 3936 ± 8 Ma, which is interpreted as an impact event. A similar age of 3941 ± 5 Ma (n = 17, MSWD = 0.89, P = 0.58) was obtained for a large zircon grain (~430 × 340 μm in size). This grain might have crystallized in the same impact melt sheet which formed the granular zircon or the age is representative of the final extrusion of KREEP magma. The majority of zircon grains, however, occur as isolated crystal clasts within the matrix and their ages cannot be correlated with any real events (impact or magmatic) nor can the possibility be excluded that these ages represent partial resetting of the U-Pb system.

Miller Range (MIL) 13317 is a heterogeneous basalt-bearing lunar regolith breccia that provides insights into the early magmatic history of the Moon. MIL 13317 is formed from a mixture of material with clasts having an affinity to Apollo ferroan anorthosites and basaltic volcanic rocks. Noble gas data indicate that MIL 13317 was consolidated into a breccia between 2610 ± 780 Ma and 1570 ± 470 Ma where it experienced a complex near-surface irradiation history for ~835 ± 84 Myr, at an average depth of ~30 cm. The fusion crust has an intermediate composition (Al2O3 15.9 wt%; FeO 12.3 wt%) with an added incompatible trace element (Th 5.4 ppm) chemical component. Taking the fusion crust to be indicative of the bulk sample composition, this implies that MIL 13317 originated from a regolith that is associated with a mare-highland boundary that is KREEP-rich (i.e., K, rare earth elements, and P). A comparison of bulk chemical data from MIL 13317 with remote sensing data from the Lunar Prospector orbiter suggests that MIL 13317 likely originated from the northwest region of Oceanus Procellarum, east of Mare Nubium, or at the eastern edge of Mare Frigoris. All these potential source areas are on the near side of the Moon, indicating a close association with the Procellarum KREEP Terrane. Basalt clasts in MIL 13317 are from a very low-Ti to low-Ti (between 0.14 and 0.32 wt%) source region. The similar mineral fractionation trends of the different basalt clasts in the sample suggest they are comagmatic in origin. Zircon-bearing phases and Ca-phosphate grains in basalt clasts and matrix grains yield 207Pb/206Pb ages between 4344 ± 4 and 4333 ± 5 Ma. These ancient 207Pb/206Pb ages indicate that the meteorite has sampled a range of Pre-Nectarian volcanic rocks that are poorly represented in the Apollo, Luna, and lunar meteorite collections. As such, MIL 13317 adds to the growing evidence that basaltic volcanic activity on the Moon started as early as ~4340 Ma, before the main period of lunar mare basalt volcanism at ~3850 Ma.