The distribution of water in the Moon's interior carries implications for the origin of the Moon
, the crystallization of the lunar magma ocean
and the duration of lunar volcanism
. The Chang'e-5 ...mission returned some of the youngest mare basalt samples reported so far, dated at 2.0 billion years ago (Ga)
, from the northwestern Procellarum KREEP Terrane, providing a probe into the spatiotemporal evolution of lunar water. Here we report the water abundances and hydrogen isotope compositions of apatite and ilmenite-hosted melt inclusions from the Chang'e-5 basalts. We derive a maximum water abundance of 283 ± 22 μg g
and a deuterium/hydrogen ratio of (1.06 ± 0.25) × 10
for the parent magma. Accounting for low-degree partial melting of the depleted mantle followed by extensive magma fractional crystallization
, we estimate a maximum mantle water abundance of 1-5 μg g
, suggesting that the Moon's youngest volcanism was not driven by abundant water in its mantle source. Such a modest water content for the Chang'e-5 basalt mantle source region is at the low end of the range estimated from mare basalts that erupted from around 4.0 Ga to 2.8 Ga (refs.
), suggesting that the mantle source of the Chang'e-5 basalts had become dehydrated by 2.0 Ga through previous melt extraction from the Procellarum KREEP Terrane mantle during prolonged volcanic activity.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
The solar system could be separated into two zones based on the isotopic dichotomy between non-carbonaceous and carbonaceous groups, with the latter likely accreted in the outer solar system. Among ...carbonaceous groups, the CM chondrite contains high abundances of organic carbon and water. They have undergone aqueous alteration, thermal metamorphism and brecciation to different degrees (e.g., Rubin et al., 2007; Tonui et al., 2014; Zolensky et al., 1997), which contributed to erasing most of the solar nebular records. Asuka 12169 was reported as the most primitive CM chondrite based on petrological and geochemical results, with little aqueous alteration (Kimura et al., 2020). In this paper, we report a survey of presolar grains in the fine-grained matrix and the accretionary rims of chondrules and CAIs in this meteorite, based on NanoSIMS mapping of C-, O-, and Si-isotopes. A total of 158 presolar grains were identified, including 119 silicates/oxides (208 ± 20 ppm), 38 SiC (73 ± 12 ppm) and 1 carbonaceous grain (2-2+5 ppm). These abundances are within the maximum abundance ranges of primitive chondrites (80–280 ppm for O-rich grains and 10–180 ppm for C-rich grains). In comparison with most CM chondrites (<40 ppm), Asuka 12169 is uniquely rich in presolar silicates (185 ± 18 ppm), with a high presolar silicate/oxide ratio of ∼8, therefore providing robust evidence for little aqueous alteration. The high abundances of presolar SiC and silicates in Asuka 12169 clearly show its pristine properties regarding both thermal and aqueous alteration. Group 1, 2, 3 and 4 subtypes of presolar O-rich grains account for 84%, 2.5%, 0.8% and 12.6%, respectively. One O-rich grain shows a high enhancement in 17O/16O and a subsolar 18O/16O ratio (17O/16O = 6.45 ± 0.09 × 10−3 and 18O/16O = 1.90 ± 0.02 × 10−3), indicating a stellar origin in binary star systems or novae. Most identified presolar SiC are mainstream grains of AGB origins. One with 28Si-excess is classified as an X grain, suggesting a supernova origin. There are two SiC grains that have 12C/13C < 10 but close-to-solar Si isotopic ratios, and are therefore classified as AB type. The pristine features of Asuka 12169 suggest that it was probably located in the outermost few kilometers of the CM asteroid, where temperature was high enough for sublimation of water ice under vacuum, but where no aqueous alteration occurred, and where the depth was enough for lithification. The high abundances of various types of presolar grains, together with the petrographic information of Asuka 12169, provide crucial constrains on the original properties and subsequent evolution of the CM asteroids.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Soil aggregates are often considered the basic structural elements of soils. Aggregates of different size vary in their ability to retain or transfer heavy metals in the environment. Here, after ...incubation of a sieved (<2 mm) topsoil with copper, bulk soil was separated into four aggregate-size fractions and their adsorption characteristics for Cu were determined. By combining nano-scale secondary ion mass spectrometry and C-1s Near Edge X-ray Absorption Fine Structure Spectroscopy, we found that copper tends to bind onto organic matter in the <2 μm and 20–63 μm aggregates. Surprisingly, Cu correlated with carboxyl-C in the <2 μm aggregates but with alkyl-C in the 20–63 μm aggregates. This is the first attempt to visualize the spatial distribution of copper in aggregate size fractions. These direct observations can help improve the understanding of interactions between heavy metals and various soil components.
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•Aggregates of different size vary in their ability to retain Cu.•Aging promotes Cu binding onto organic matter in the <2 μm and 20–63 μm aggregates.•Cu correlates with carboxyl-C in the <2 μm aggregates but with alkyl-C in the 20–63 μm aggregates.
Copper tends to bind onto organic matter in the <2 μm and 20–63 μm aggregates, while correlates with carboxyl-C in the <2 μm aggregates and with alkyl-C in the 20–63 μm aggregates.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The lunar Mg-suite magmatic rocks are commonly thought to represent mafic intrusions into the anorthositic flotation crust of the lunar magma ocean (LMO). Their geochronology is, therefore, important ...for constraining evolution models of the LMO. Petrogenetic models of the Mg-suite hold that their parent magmas were derived from primary LMO sources (Mg-cumulates, An-rich plagioclase, and melts enriched in KREEP—potassium, rare earth elements, and phosphorus). Previous radiogenic isotopic age interpretations of Mg-suite and putatively older, related ferroan anorthosites (FANs) overlap over a 200-million-year interval. The Apollo 78238 norite is an exemplary Mg-suite rock, with a relict coarse igneous texture modified by shock metamorphism. In-situ secondary ion mass spectrometry U-Pb analyses of zircon and baddeleyite in 78238 yield discordant arrays, attributed to recent impact metamorphism, with upper intercepts that constrain its crystallization age. The four oldest baddeleyite analyses give a weighted mean 207Pb/206Pb age of 4332 ± 18 Ma (2σ, MSWD = 0.06, P = 0.98), which is interpreted as the crystallization age of the norite. The overlap of the baddeleyite age with previously reported Sm-Nd and Pb-Pb mineral isochron ages for 78238 (Edmunson et al., 2009) supports a moderately fast cooling of the norite. Moreover, it is distinguishably younger than the most precisely dated sample of FAN (Apollo 60025), measured at 4360 ± 3 Ma by Sm-Nd and Pb-Pb mineral isochrons (Borg et al., 2011). Together with the baddeleyite 207Pb/206Pb age of Apollo Mg-suite troctolite 76535 at 4328 ± 8 Ma (White et al., 2020), the chronological record of the 78238 norite indicates a significant Mg-suite magmatic event at 4.33 Ga and a lower age limit on LMO differentiation.
•First SIMS U-Pb dating for Apollo norite 78238 is performed by 5 μm primary beam.•A baddeleyite grain in 78238 has a 207Pb/206Pb crystallization age of 4332 ± 18 Ma.•The 207Pb/206Pb age of 78238 is resolvably younger than the age of ferroan anorthosite 60025.•The 207Pb/206Pb age supports a pulse of the Mg-suite magmatism at ∼4330 Ma.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Zircons and apatites in clasts and matrix from the Martian breccia NWA 7034 are well documented, timing ancient geologic events on Mars. Furthermore, in this study, zircon trace elemental content, ...apatite volatile content, and apatite volatile isotopic compositions measured in situ could constrain the evolution of those geologic events. The U‐Pb dates of zircons in basalt, basaltic andesite, trachyandesite igneous clasts, and the matrix are similar (4.4 Ga) suggesting intense volcanism on ancient Mars. However, two metamict zircon grains found in the matrix have an upper intercept date of ~4465 Ma in crystalline, whereas amorphous areas have a lower intercept date of 1634 ± 93 Ma. The younger date is consistent with the date of apatites (1530 ± 65 Ma), suggesting a metamorphic event that completely reset the U‐Pb system in both the amorphous areas of zircon and all apatites. δD values in all apatites negatively correlate with water content in a two‐endmember mixing trend. The D (δD up to 2459‰) and 37Cl heavy core (3.8‰) of a large apatite grain suggest a D‐, 37Cl‐rich fluid during the metamorphic event ~1.6 Ga ago, consistent with the trace elements Y, Hf and Ti and P in zircons. The fluid was also therefore P‐rich. The D‐, 37Cl‐poor H2O‐rich rim (<313‰) suggests the degassing of water from the Martian Cl‐poor interior at a later time. This D‐, 37Cl‐poor Martian mantle reservoir could have derived from volcanic intrusions postdating the younger metamorphic event recorded in NWA 7034.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•The martian mantle reservoir is H2O-, S-, and Cl-poorer than the Earth's interior.•Martian surface Cl was preserved in melt inclusions via water-rock interaction.•The martian surface water reservoir ...might be homogeneous in δD values.•S-rich hotspots and dendritic H2O-rich bands were detected from melt inclusions.
Martian meteorites of various petrogeneses retain a record of volatiles on Mars: from the hydrosphere, crustal water to the mantle. Sputtering of the martian atmosphere by solar wind after the loss of Mars' magnetic field enriched it in deuterium, which exchanged with martian crustal water. Recent studies show that the hydrogen isotopic composition of the martian crustal water reservoir varies from 3000 to 7000‰ but requires better constraints. Melt inclusion glasses, maskelynite and fusion crust from the depleted olivine-phyric shergotite NWA 6162 were analyzed using NanoSIMS, providing a unique insight into the hydrogen isotopic and volatile elemental content of both the martian crustal water reservoir and the mantle source.
The H2O, S, and Cl contents of the melt inclusion glasses are ∼0-3137, 14-239, and 16-967 ppm, respectively. δD values vary from −560 to 6137‰. The water content positively correlates with the δD values in both the melt inclusion glasses and maskelynite in a two end-member mixing trend. One end-member is the magmatic water with a δD value of ∼0‰, and the other end member is the martian crustal water with δD ranging from 5000 to 6000‰. NWA 6162, a depleted olivine-phyric shergottite, originated from a different mantle source to the enriched lherzolitic shergottites. However, both types of shergottites exchanged with martian crustal water with the same δD values, indicating a homogeneous martian crustal water hydrogen isotopic composition (5000-6000‰). Most melt inclusion glasses from NWA 6162 have low water content (0-234 ppm) except for two enriched locations as micron-sized bands and dendrites. The low water content in most melt inclusion glasses, the dendritic shaped water enriched areas in melt inclusions, and the martian crustal water diffusion profile recorded in maskelynite collectively suggest short-lived water-rock interactions in the NWA 6162 parent rock that was probably induced by impact. Furthermore, a great contribution (up to 98%) of surface Cl accompanying D-enriched water was recorded in the melt inclusions supported by the positive correlation between Cl and H2O. The presence of sulfide and S-rich hot spots and low δD end-member of the magmatic water indicate that the degassing during post-entrapment crystallization and ascent of the melt inclusion is negligible. H2O, S, and Cl contents of the martian mantle reservoir are estimated to be 0.1-3, 0.5-15, and 0.5-4 ppm respectively, after the correction of fractional crystallization of the melt inclusions and contribution from the martian surface reservoir. The martian mantle reservoir estimated from NWA 6162 was water-, S-, and Cl-poorer than the Earth's interior.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Paleoclimate research has built a framework for Earth’s climate changes over the past 65 million years or even longer. However, our knowledge of weather-timescale extreme events (WEEs, also named ...paleoweather), which usually occur over several days or hours, under different climate regimes is almost blank because current paleoclimatic records rarely provide information with temporal resolution shorter than monthly scale. Here we show that giant clam shells (Tridacna spp.) from the tropical western Pacific have clear daily growth bands, and several 2-y-long (from January 29, 2012 to December 9, 2013) daily to hourly resolution biological and geochemical records, including daily growth rate, hourly elements/Ca ratios, and fluorescence intensity, were obtained. We found that the pulsed changes of these ultrahigh-resolution proxy records clearly matched with the typical instrumental WEEs, for example, tropical cyclones during the summerautumn and cold surges during the winter. When a tropical cyclone passes through or approaches the sampling site, the growth rate of Tridacna shell decreases abruptly due to the bad weather. Meanwhile, enhanced vertical mixing brings nutrient-enriched subsurface water to the surface, resulting in a high Fe/Ca ratio and strong fluorescence intensity (induced by phytoplankton bloom) in the shell. Our results demonstrate that Tridacna shell has the potential to be used as an ultrahigh- resolution archive for paleoweather reconstructions. The fossil shells living in different geological times can be built as a Geological Weather Station network to lengthen the modern instrumental data and investigate the WEEs under various climate conditions.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
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•The framboidal pyrites have low concentrations of some trace elements (e.g., Co, Ni, Cu, Cr, Au, As).•The framboidal structure and fluidic activities facilitated the incorporation of ...trace elements.•In situ δ34S values of the pyrites supported a biotic origin with bacterial sulfate reduction.•Four-stage model is suggested to interpret the genesis and evolution of the pyrites.
Southwestern Guizhou, an indispensable component of the “golden triangle” area of southwestern China, is famous for its numerous Carlin-style gold deposits. Unlike other sulfides in the deposits that have been well studied, the genesis of framboidal pyrite is still controversial because of its tiny size. Here, we first determined the chemical and in situ sulfur isotopic compositions of framboidal pyrites from three typical Carlin-style gold deposits (namely Shuiyindong, Taipingdong and Nibao) using secondary electron image (SEI), back scattered electron (BSE), electron probe micro analysis (EPMA), and nanometer-scale secondary ion mass spectroscopy (Nano-SIMS) methods. Our EPMA data show that the framboidal pyrites contain a minor amount of trace elements (Ni < 0.344 wt%, Co = 0.017–0.295 wt%, Cr = 0.009–0.292 wt% and As < 1.479 wt%). Incorporation of the trace elements into the framboidal pyrites resulted in a slight decrease in S and Fe concentrations compared to the theoretical values. The in situ δ34S values of the framboidal pyrites, ranging from −53.2‰ to −30.9‰, are in good agreement with the sulfur isotopic fractionation triggered by the bacterial sulfate reduction (BSR) process in an open-SO42− ocean condition. Combined with SEI, BSE, and Nano-SIMS high-resolution multiple elemental mapping, four consecutive processes responsible for their genesis and evolution are summarized as follows: (1) initial microcrystal nucleation via the BSR process, (2) abundant microcrystal aggregation to form individual framboid and multiple-framboids during sedimentation or diagenesis, (3) partial replacement and recrystallization of preexisting framboids by As-rich ore fluids, and (4) eventual framboidal pyrite transformation to larger euhedral grains via continuous recrystallization. These processes not only present compelling mechanisms responsible for the variations in morphology and chemical composition of the framboidal pyrites, from the initial framboid with a low 75As32S signal (Py1) to the framboid with a recrystallization origin (Py3), but also indicate that their genesis and evolution may have an intimate correlation with the formation of Carlin-style gold deposits.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The Moon can have elevated chlorine (Cl) isotope ratios, much higher than any other Solar System objects. Deciphering the Cl isotope compositions of volcanic lunar samples is critical for unraveling ...the volcanic processes and volatile inventory of the Moon's interior. However, the processes and mechanisms of Cl isotope fractionation are not yet fully understood through previous studies on lunar samples. The China's Chang'e-5 (CE5) basalt samples were collected far from the Apollo and Luna landing sites, and dated at about 2.0 billion years ago (Ga), approximately 1 Ga younger than previously reported lunar basalts. The CE5 samples, therefore, provide an opportunity to investigate Cl isotope characteristics and fractionation mechanisms during a younger lunar volcanism. In this study, we performed systematic petrography, mineral chemistry, volatile abundances and distribution, and Cl isotopic studies on the CE5 apatite via a combination of scanning electron microscopy, electron probe microanalyser, and nanoscale secondary ion mass spectrometry. The CE5 apatite grains from basalt clasts and fragments have subhedral to euhedral shapes with grains sizes mostly less than 10 μm, mainly coexisting with the mesostasis, fayalite olivine, and the margins of pyroxene. These apatites are F-dominated (0.91-3.93 wt%) with a Cl abundance range of 820 to 11989 μg.g−1 and a water abundance range of 134 to 6564 μg.g−1, similar to those in the mare samples previously reported. Chlorine displays notable zoning distributions in some CE5 apatite grains with higher abundance at the rims gradually decrease towards the cores. Chlorine isotopic compositions of CE5 apatite vary from 4.5 to 18.9‰, positively correlated with the Cl abundances. These lines of evidence suggest that magmatic degassing of Cl-bearing species during the crystallisation of apatite at or near the lunar surface could have resulted in a large Cl isotope fractionation. Our new findings highlight a significant role of magmatic fractionation of Cl isotopes during crystallisation of mare lavas and provide clues for determining the primordial Cl isotopic signature of the Moon.
•We measured the Cl isotope and Cl abundance in the Chang'e-5 (CE5) mare apatite.•The Cl isotope and Cl abundance of CE5 apatite are positively correlated.•Water, F and Cl of CE5 apatite are heterogeneously distributed within single grain.•The CE5 apatite experienced a magmatic Cl isotope fractionation on the Moon.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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