Terrestrial Samples Research Articles

Round up the unusual suspects: Near-Earth Asteroid 17274 (2000 LC16) a plausible D-type parent body of the Tagish Lake meteorite

Asteroids are the origin point for most meteorites impacting Earth. Terrestrial meteorite samples provide evidence of what actually occurred in the early solar system at the formation location of the meteorite, and when it occurred. The ability to connect a meteorite sample to an asteroid parent body provides its starting location as a meteoroid. To date, only a handful of chondritic meteorite types have been credibly connected to an asteroid parent. For the past two decades, D-type asteroids, a dark, spectrally reddish, and featureless taxonomic type have been speculated to be the parent body of the tiny family of ungrouped chondrites. These include the Tagish Lake Meteorite (TLM), a ~ 4 m meteorite “fall” in Canada's Yukon territory recovered in 2000. The quest to identify the TLM parent has been a baffling one as D-type asteroids are dominant among the Jovian Trojans, rare in main asteroid belt, and extremely rare in the inner asteroid belt as well as Near-Earth space.This study employed Near Infrared (NIR) spectra (0.7–2.45 μm) of 86 D-types and a variety of analysis techniques including visual analysis, slope analysis, curve fitting, Fréchet analysis, dynamical analysis and Shkuratov radiative transfer theory to search for the TLM parent body. Sixteen TLM samples from the NASA Reflectance Experiment Laboratory (RELAB) plus five additional mineralogically well-constrained samples measured using X-ray diffraction (XRD) and Rietveld refinement were compared to D-type asteroid spectra. Our results indicate, out of several promising candidates, Near-Earth asteroid 17274 (2006 LC16), a ~ 3 km diameter Amor asteroid is a plausible parent body for TLM.

Evaluation of terrestrial gastropods as possible intermediate hosts of Gurltia paralysans in southern Chile.

Gurltia paralysans is the causal agent of gurltiosis in domestic cats in South America. Although the life cycle of G. paralysans is unknown, it is thought that gastropods could act as intermediate hosts (IHs), as is the case for several nematodes in the Angiostrongylidae family. The aim of this study was to search for G. paralysans larvae in terrestrial gastropods and determine their role in the life cycle of this nematode species. Terrestrial gastropod samples (n=835) were collected in Punucapa, Valdivia, southern Chile, where cases of gurltiosis had been reported before. The samples included species from the families Arionidae, Limacidae, Helicidae and Milacidae. All gastropods were subjected to enzymatic digestion to isolate G. paralysans larvae. Ten percent of the gastropod samples were analyzed using seminested PCR targeting the 28S rRNA gene, while 2.6% were analyzed by histopathological examination. The results indicated the absence of G. paralysans when using any of the three methods. In conclusion, further studies are needed to evaluate specific species of aquatic or native gastropods acting as possible IHs (in this geographic location).

Titanium isotope fractionation in solar system materials

New methods to determine the titanium (Ti) mass-dependent isotope fractionation of solar system materials to high precision were developed by combining internally normalised Ti isotope data with double-spike analyses utilising a 47Ti-49Ti double spike. The procedure includes a three-stage ion-exchange separation procedure to isolate Ti from the sample matrix that provides high-purity Ti fractions that are necessary for high-precision Ti isotope analyses. Analyses of sample aliquots that were spiked before and after the ion-exchange separation procedure demonstrate that Ti isotope fractionation can be induced by the separation procedure. This outcome requires the addition of the double spike before the ion exchange separation procedure in order to accurately determine the natural mass-dependent Ti isotope fractionation of samples. Multiple double spike analyses of an Alfa Aesar Ti standard performed over eight months yielded a reproducibility (2σ standard deviation) of 0.033‰ for δ49/47Ti (differences in 49Ti/47Ti relative to the OL-Ti standard). Terrestrial sample analyses display a 2σ reproducibility of 0.018 to 0.031‰ for δ49/47Ti. Titanium isotope results for three terrestrial USGS magmatic reference samples (AGV-2, BHVO-2 and BCR-2) agree well with literature data and therefore demonstrate the accuracy and precision of the presented methodologies. Achondritic meteorites display an overall range of 0.75‰ for δ49/47Ti. The ungrouped achondrite NWA 7325 has a more positive composition by 0.64‰ for δ49/47Ti compared to all other investigated samples likely reflecting Ti isotope fractionation induced by magmatic differentiation associated with highly reducing conditions and potentially associated with oxide and plagioclase formation. In contrast, eucrites with δ49/47Ti of -0.020 ± 0.070 and -0.003 ± 0.033 and the first mass-dependent Ti isotope data for an acapulcoite (Dhofar 125; δ49/47Ti = 0.094 ± 0.033) show only limited magmatic Ti isotope fractionation. Chondrites also display a relatively restricted range of 0.085‰ for δ49/47Ti, including one calcium‑aluminum rich inclusion (CAI) from Allende and the first mass-dependent Ti isotope data for two Rumuruti chondrites (NWA 753 and NWA 755). Furthermore, the mass-dependent Ti isotope composition of chondrites overlaps with that of eucrites and the acapulcoite Dhofar 125 indicating that nebular processes induce only limited Ti isotope fractionation. Additionally, the Ti isotope data indicate that thermal metamorphism also produced marginal Ti isotope fractionation at the bulk sample scale for chondrites. Small mass-dependent Ti isotope variations between different bulk meteorite samples are also evident, which might reflect sample heterogeneity. Importantly, the mass-dependent Ti isotope composition of the Earth and Moon overlap with the composition of the investigated chondrites, eucrites and acapulcoites within the 2 standard deviation uncertainties.

Widespread fluorescence in terrestrial and marine samples investigated from India

The discovery of green fluorescent protein (GFP) from jellyfish Aequorea victoria has provoked numerous studies to unveil the myriads of biomedical applications. Consequently, several studies also revealed the prevalence of fluorescence in different marine and terrestrial organisms. However, since GFP's discovery or the Nobel prize award on GFP, the fluorescence has not been explored so far from India. The current study presents the widespread fluorescent organisms resources available in India for biomedical and toxicological applications. Fluorescence emission from different plant and animal components were examined by direct observations using UV torchlight. Investigation revealed that blue light excited fluorescence in several organisms. For the first time, this study observed GFP like fluorescence in many terretrial and marine organisms of India. Observations are indicating that fluorescent proteins have essential ecological functions that are yet to be determined. The examined plant and animal components were not bioluminescent. In comparison, the potential untouched research areas on fluorescence aspects are detailed. A thorough review of fluorescent organisms reported hitherto is also provided to spread the current knowledge on fluorescence.

Transuranic nuclides Pu, Am and Cm isotopes, and 90Sr in seafloor sediments off the Fukushima Daiichi Nuclear Power Plant during the period from 2012 to 2019

The 238Pu, 239+240Pu, 241Am, 242Cm, 243+244Cm and 90Sr concentrations in seafloor surface sediments collected at three sampling stations off the Fukushima Daiichi Nuclear Power Plant (FDNPP) site during the period from 2012 to 2019 were determined to elucidate the impacts of the FDNPP accident onto their concentrations in coastal sediments and to discuss the sources of the measured radionuclides. The 239+240Pu, 241Pu and 241Am concentrations and 240Pu/239Pu atom ratios in a sediment core were also determined to allow comparison of their inventories between this study and previously reported values and to identify the Pu sources. The 238Pu, 239+240Pu, 241Am and 90Sr concentrations showed no remarkable temporal variations; no significant increases in concentrations after the FDNPP accident were observed; these concentrations were comfortably within the previously reported concentration range; and no detectable 242Cm and 243+244Cm amounts were observed in surface sediments. The observed 238Pu/239+240Pu activity ratios were approximately two orders of magnitudes lower than those for the damaged FDNPP reactor core inventories and the observed values in terrestrial samples after the accident. The 239+240Pu, 241Pu and 241Am inventories in the sediment core were 389 ± 5, 503 ± 33 and 214 ± 3 Bq m−2, respectively. The 239+240Pu inventory was about an order of magnitude greater than the expected cumulative deposition density of global fallout from atmospheric nuclear weapons testing due to an enhanced scavenging effect. The 240Pu/239Pu atom ratios in the sediment core ranged from 0.239 to 0.246 with a mean value of 0.242 ± 0.002; these ratios were clearly greater than the mean global fallout ratio of 0.18. The results for 238Pu/239+240Pu activity ratios and 240Pu/239Pu atom ratios reflected a mixture of global fallout and Pacific Proving Grounds (PPG) close-in fallout Pu rather than Fukushima accident-derived Pu. The sediment column inventory for 239+240Pu originating from the PPG close-in fallout was calculated as 166 Bq m−2, which corresponded to 43% of the total inventory. A significant amount of the PPG-derived Pu has been transported by ocean currents and then preferentially scavenged in the coastal waters of Japan.

Determination of the refractory enrichment factor of the bulk silicate Earth from metal-silicate experiments on rare Earth elements

This study investigates the partitioning of rare earth elements (REE) from La to Gd between molten metal and silicate to evaluate potential fractionation occurring during core-mantle differentiation. We report molten metal-silicate liquid partition coefficients from 24 multi-anvil experiments, extending the range of pressure, previously ranging from 1 to 8 GPa, up to 14 GPa. Experiments were performed at temperatures of between 2300 and 2560 K, and for oxygen fugacities ranging from the IW (Iron-Wüstite buffer) to IW–4. Metal-silicate partition coefficients for the studied REE vary with the oxygen fugacity and S concentration in the metallic phase of the system. These elements were all lithophile during the Earth's accretion. By compiling all existing data on molten metal-silicate liquid partitioning, REE partitioning between the mantle and core during the Earth's accretion can be determined for a wide range of P, T and fo2 conditions representing the early evolution of planetary bodies from planetesimals to planets. REE concentrations of the bulk silicate Earth (BSE) are calculated from accretion scenarios using varying proportions and compositions of chondritic building blocks. The models selected are those that reproduce the Earth's nucleosynthetic isotope signature and the Ni/Co, Th/U and Nb/Ta ratios of the BSE. The BSE refractory element enrichment factor determined from REE data is equal to 2.88 (relative to CI chondrites). This calculation takes into account the depletion in volatile elements in the Earth compared to chondrites. This new estimate is in good agreement with previous determinations based on analysis of the upper mantle rocks, which supports the idea of a chemically homogeneous mantle. We also confirm that the formation of the core, with or without segregation of a sulfide phase, does not fractionate Sm/Nd and cannot be responsible for the 142Nd excess measured in modern terrestrial samples relative to chondrites.

Optimisation of a batch thermal combustion method using a tube furnace oxidation system (pyrolyser) and LSC for carbon-14 determination in environmental matrices

Accelerator mass spectrometry and benzene synthesis coupled with liquid scintillation spectrometry are often used for accurate measurements of 14C activity in the environmental matrices. Thermal oxidation is one of the methods employed for 14C determination in environmental matrices. In this method, the sample is oxidised at high temperature (600–900 °C) to convert carbon species to CO2 and trapped in an amine-based absorber for determining the activity in a liquid scintillation counting (LSC) system. In this study, the performance of a commercially available tube furnace system (pyrolyser), for batch combustion of samples, was evaluated for the determination of 14C specific activity in terrestrial biota samples. Significant improvements over the manufacturer specified method, which is primarily designed for analysis of samples with activity well above the environmental background level, was implemented to achieve accurate determination of 14C specific activity at ambient background level. In the improved method, the CO2 produced from the combustion of the sample was isolated from the combustion products through cryogenic trapping and then absorbed in the absorber (Carbo-Sorb E) through a simple off-line transfer process. This allowed (i) optimisation of CO2 absorption by the absorber (2.2477 g of CO2/10 mL), (ii) achieving good accuracy and precision in the measurements, and a minimum detectable activity value of 13 Bq kg−1C for a counting time of 300 min (7 Bq kg−1C for 1000 min), (iii) avoiding uncertainty associated with the determination of recovery of 14C in the combustion and trapping process, and (iv) elimination of the need for an independent determination of carbon content (%) for expressing the results in terms of 14C specific activity. The method is capable of yielding accurate results with a deviation of <2.4% from the target value for IAEA C3 quality assurance reference material (with a relative standard deviation of 1.40%, and relative error of 0.34%). The combined uncertainty (1σ) associated with the measurements was computed to be 3.4%. Upon optimisation, the suitability of the method for the determination of 14C specific activity in typical terrestrial biota samples of clean air region (region not affected by local anthropogenic sources) and for the quantification of a small increase in the 14C activity above ambient levels in the vicinity of a nuclear power plant is demonstrated.

Pb-Pb Dating of Terrestrial and Extraterrestrial Samples Using Resonance Ionization Mass Spectrometry.

We are developing an in situ, rock‐dating spectrometer for spaceflight called the Chemistry, Organics, and Dating EXperiment (CODEX). CODEX will measure Rb‐Sr compositions and determine ages of samples on the Moon or Mars and can be augmented to obtain Pb‐Pb ages. Coupling Rb‐Sr and Pb‐Pb measurements broadens the suite of samples that can be dated and could provide tests of concordance. Here we assess whether geochronologically meaningful Pb‐Pb data could be measured in situ by tuning the prototype CODEX to acquire Pb‐Pb data from a suite of well‐characterized specimens from the Earth, Moon, and Mars. For Keuhl Lake Zircon 91500 our 207Pb/206Pb age of 1,090 ± 40 Ma is indistinguishable from the accepted age. In each of the Martian meteorites we studied, we could not resolve more than a single component of Pb and could not uniquely determine ages; nevertheless, our isotopic measurements were consistent with most previous analyses. On the other hand, we uniquely determined ages for three lunar meteorites. Our age for MIL 05035 is 3,550 ± 170 Ma, within 2σ of published ages for this specimen, in spite of it having <1 ppm Pb. LAP 02205 was contaminated by terrestrial Pb, but by filtering our data to exclude the most contaminated spots, we obtained an age of 3,010 ± 70 Ma, coincident with published values. Finally, our age for NWA 032 is nearly 1,000 Ma older than its age determined from other isotopic systems and is supported by additional Pb measurements made after chemical leaching.

Water-bearing characteristics and their influences on the reservoir capacity in terrestrial shale reservoirs: A case study of the lower Jurassic Ziliujing Formation in the Northeast Sichuan Basin, China

The water content in shale reservoirs has a negative effect on reservoir space capacity. Compared with marine shale, terrestrial shale is characterized by higher clay content and lower total organic carbon (TOC), which is more sensitive to water and decreases gas storage capacity. However, it is still not fully understood how water is distributed in nanopores and how shale reservoir capacity is significantly weakened. In this study, a series of measurements were conducted methodically, including a moisture-equilibrated experiment, high-pressure mercury injection, gas adsorption, air-liquid contact angle, spontaneous imbibition and nuclear magnetic resonance, to investigate the water-bearing characteristics and effects of lacustrine shale. On the macroscopic scale, it was confirmed that clay shale displays the strongest water adsorption capacity and holds 2–3 times more water than siliceous shale. Clay minerals, especially montmorillonite, adsorb approximately 4 times more water than shale and 20 times more water than kerogen at a relative humidity (RH) of 98%. Meanwhile, clay shale with high TOC adsorbed less water. At the microscopic scale, the pore structure parameters of pore volume (PV) and specific surface area (SSA) can decrease up to 1/2 and 1/3, respectively, which based on our terrestrial shale samples at the RH of 98%. Furthermore, PV declines with increasing RH, primarily between 2.5 nm and 80 nm, while SSA also declines and fluctuates from 2.5 nm to 20 nm with increasing RH, which suggests that SSA is more susceptible to water than PV. When the RH increases from 0% to 98%, the minimum critical aperture (DCAmin) of the pore size shows an obvious shift from 2.5 nm to 7.5 nm, indicating that some nanopores are gradually damaged by water vapor and are unavailable for gas storage. In addition, water saturation in shale reservoirs maintains dynamic changes with thermal evolution. Finally, we proposed a multifactor controlled dynamic model and discussed the gas storage capacity of shale reservoirs with residual water. This study provides systematic and deep insight into water-bearing shale and is helpful for evaluating gas storage capacity in terrestrial reservoirs.

Theoretical insight and experimental elucidation of desferrioxamine B from Bacillus sp. AS7 as a green corrosion inhibitor

ABSTRACT A theoretical and experimental systematic study was performed to determine the structural characteristics and functionality that siderophores must have to be used as ecological corrosion inhibitors. Analyses demonstrated that the hydroxamate functional group is the best siderophore that could be used as a corrosion inhibitor of neutral or acidic environments because it would form a smart protective film as good or better than imidazoline. Bacillus sp. AS7, isolated from an extreme halo-alkaline terrestrial ecosystem soil sample is producer of desferrioxamine B, a siderophore based on trihydroxamate groups. This siderophore was purified and characterised, its efficiency as a corrosion inhibitor was determined through gravimetric techniques. The obtained siderophore works as an ecological corrosion inhibitor at a minimal concentration of 75 ppm. We demonstrated that the siderophore desferrioxamine B controls efficiently corrosion problems occurring in acid environments characteristic of the oil industry.

Investigating the Ionization of Dissolved Organic Matter by Electrospray.

Electrospray ionization (ESI) operating in the negative mode coupled to high-resolution mass spectrometry is the most popular technique for the characterization of dissolved organic matter (DOM). The vast molecular heterogeneity and the functional group diversity of this complex mixture prevents the efficient ionization of the organic material by a single ionization source, so the presence of uncharacterized material is unavoidable. The extent of this poorly ionizable pool of carbon is unknown, is presumably variable between samples, and can only be assessed by the combination of analysis with a uniform detection method. Charged aerosol detection (CAD), whose response is proportional to the amount of nonvolatile material and is independent from the physicochemical properties of the analytes, is a suitable candidate. In this study, a fulvic acid mixture was fractionated and analyzed by high-pressure liquid chromatography–mass spectrometry in order to investigate the polarity and size distributions of highly and poorly ionizable material in the sample. Additionally, DOM samples of terrestrial and marine origins were analyzed to evaluate the variability of these pools across the land–sea aquatic continuum. The relative response factor values indicated that highly ionizable components of aquatic DOM mixtures are more hydrophilic and have lower molecular weight than poorly ionizable components. Additionally, a discrepancy between the samples of terrestrial and marine origins was found, indicating that marine samples are better represented by ESI than terrestrial samples, which have an abundant portion of hydrophobic poorly ionizable material.

Improved pretreatment method for the isolation and decontamination of pyrogenic carbon for radiocarbon dating using hydrogen pyrolysis

Abstract Pyrogenic carbon (charcoal, black carbon, elemental carbon) is one of the most common materials used for radiocarbon dating of terrestrial samples. However, exogenous carbon contamination can compromise the accuracy of radiocarbon ages. This study presents the results of two chemical pretreatments prior to hydrogen pyrolysis (hypy) as improved protocols for the isolation and decontamination of pyrogenic carbon, i) a simple acid-oxidation step (A-Ox/hypy) and ii) acid-base-acid (ABA/hypy). The A-Ox/hypy protocol uses HNO3 and H2O2, while ABA/hypy uses HCl and NaOH. Both pretreatments remove labile and inorganic carbon before hypy, decreasing the potential for in situ production of pyrogenic carbon during the hypy reaction. The effectiveness of each protocol was directly measured on charcoal artificially produced at 350 °C, 450 °C and 550 °C from radiocarbon-free wood, and exposed to environmental contamination for 1–3 yrs. The results show a >94% reduction in carbon contamination for the 450 °C and 550 °C charcoal samples occurred using A-Ox/hypy, but this treatment was less effective for the 350 °C charcoal. A >99% reduction in carbon contamination in all charcoal samples examined occurred using ABA/hypy. The A-Ox/hypy protocol was further tested on cave guano sediments, which had previously reported erroneous dates following simple organic solvent extraction followed by ABA pretreatment. Effective decontamination was achieved using A-Ox/hypy on the guano, which corrected a radiocarbon age reversal. Overall, ABA/hypy effectively decontaminated the charcoals and was a more efficient pretreatment for charcoal than A-Ox/hypy, however resulting in larger sample mass loss. Therefore, ABA/hypy is the recommended protocol for older (>30,000 14C yr BP) charcoal or sediment samples, or where date accuracy is imperative, while A-Ox/hypy represents an improved protocol for the quick and cost-effective measurement of younger samples (

Experimental database on water equivalent factor (WEQp) and organically bound tritium activity for tropical monsoonal climate region of South West Coast of India

Tritium in the form of tritiated water is easily incorporated into terrestrial biota as tissue free water tritium (TFWT). A part of TFWT is converted into organically bound tritium (OBT) through metabolic processes. For the computation of NE-OBT activity (expressed as Bq L-1 of combustion water) in terrestrial plants, knowledge on ‘water equivalent factor (WEQp)', defined as the volume of water produced from the combustion of 1 kg of the dry sample, is essential. On a global scenario, experimental data are not available on this parameter. This paper presents (i) a method for determination of WEQp by combustion method using a tube furnace system, (ii) a large database (N = 294) on WEQp parameter for samples of tropical monsoonal climate region of the Indian subcontinent, and (iii) NE-OBT activity in terrestrial biota samples (N = 186) collected from the vicinity of a PHWR nuclear power plant of India. The data generated in this study on WEQp serves for the validation of the data compiled in IAEA (2009 and 2010), which are estimated based on the hydrogen content of protein, fat and carbohydrates, and the fractions of protein, fat and carbohydrates. The WEQp varied in the ranges of 0.492–0.678 L kg-1 (GM = 0.569 Bq L-1, GSD = 1.06), 0.520–0.630 L kg-1 (GM = 0.557 Bq L-1, GSD = 1.02) 0.473–0.633 L kg-1 (GM = 0.562 Bq L-1, GSD = 1.02) for non-leafy vegetables, leafy vegetables, and fruits, respectively. A comparison between the experimental WEQp data with those compiled in the IAEA report revealed that the maximum deviation between the two data sets is <10%. The NE-OBT activity in the food samples collected from 2.3 to 20 km zone around NPP had a geometric mean (GM) value of 25.4 Bq L-1 (GSD = 1.6, N = 186). Variations in NE-OBT activity with different seasons of the year are discussed.

Cell Plasticity and Genomic Structure of a Novel Filterable Rhizobiales Bacterium that Belongs to a Widely Distributed Lineage.

Rhizobiales bacterium strain IZ6 is a novel filterable bacterium that was isolated from a suspension filtrate (<0.22 µm) of soil collected in Shimane Prefecture, western Japan. Additional closely related isolates were recovered from filterable fractions of terrestrial environmental samples collected from other places in Japan; the Gobi Desert, north-central China; and Svalbard, Arctic Norway. These findings indicate a wide distribution of this lineage. This study reports the cell variation and genomic structure of IZ6. When cultured at lower temperatures (4 °C and 15 °C), this strain contained ultra-small cells and cell-like particles in the filtrate. PacBio sequencing revealed that this chromosome (3,114,641 bp) contained 3150 protein-coding, 51 tRNA, and three rRNA genes. IZ6 showed low 16S rRNA gene sequence identity (<97%) and low average nucleotide identity (<76%) with its closest known relative, Flaviflagellibacter deserti. Unlike the methylotrophic bacteria and nitrogen-fixing bacteria in related genera, there were no genes that encoded enzymes for one-carbon-compound utilization and nitrogen fixation in the IZ6 genome; the genes related to nitrate and nitrite reductase are retained and those related to the cell membrane function tend to be slightly enriched in the genome. This genomic information helps elucidate the eco-physiological function of a phenotypically heterogeneous and diverse Rhizobiales group.

Geochemical Constraints on the Origin of the Moon and Preservation of Ancient Terrestrial Heterogeneities

The Moon forming giant impact marks the end of the main stage of Earth’s accretion and sets the stage for the subsequent evolution of our planet. The giant impact theory has been the accepted model of lunar origin for 40 years, but the parameters of the impact and the mechanisms that led to the formation of the Moon are still hotly debated. Here we review the principal geochemical observations that constrain the timing and parameters of the impact, the mechanisms of lunar formation, and the contemporaneous evolution of Earth. We discuss how chemical and isotopic studies on lunar, terrestrial and meteorite samples relate to physical models and how they can be used to differentiate between lunar origin models. In particular, we argue that the efficiency of mixing during the collision is a key test of giant impact models. A high degree of intra-impact mixing is required to explain the isotopic similarity between the Earth and Moon but, at the same time, the impact did not homogenize the whole terrestrial mantle, as isotopic signatures of pre-impact heterogeneity are preserved. We summarize the outlook for the field and highlight the key advances in both measurements and modeling needed to advance our understanding of lunar origin.

FROM LAND AND SEA: OVERCOMING THE CHALLENGES OF DIRECTLY DATING DOG REMAINS ON POLYNESIAN ISLANDS

ABSTRACTRecent archaeological excavations on Rakahanga Atoll, Northern Cook Islands, produced one of the earliest examples of dog (Canis familiaris) remains found on East Polynesian atolls. Direct dating of these and other Pacific Island fauna by AMS is complicated by a number of factors. (1) The animals’ diets may consist of marine and terrestrial protein. (2) Marine 14C is itself a mix of carbon pools with localized offsets that vary over time and space. (3) The region is potentially impacted by inter-hemispheric mixing of atmospheric 14C. Stable isotope analysis of gelatin extracted from dog teeth was used to estimate marine/terrestrial dietary components and paired terrestrial and marine samples were used to constrain local atmospheric and marine carbon offsets. The dates were modeled as a phase in a Bayesian chronological framework using mixed calibration curves. The resulting models confirm the presence of dogs on Rakahanga shortly after the initial colonization of the region and suggest that dogs were among the species that accompanied voyagers as they discovered and settled new islands. These methods can be applied to accurately date any marine-influenced terrestrial vertebrate remains in Remote Oceania.

Best Fit for Complex Peaks (BFCP) in Matlab® for quantitative analysis of in situ 2D X-Ray diffraction data and Raman spectra

Large mineral grains that have undergone shock metamorphism or tectonic stress can exhibit plastic deformation. Using in situ micro X-Ray diffraction, such deformation is revealed in a 2D detector image by distortion of diffraction spots into an angular spread or ‘streaking’ along Debye ring or chi (χ) dimension; this can provide a quantitative measurement of plastic deformation via full width at half maximum (FWHMχ) measurement of the diffraction profile along χ. Often the X-ray intensity is not a single homogeneous streak, but is partitioned into discrete orientationally-related spots along the Deybe ring, called asterism. These complex peaks require more sophisticated fitting. This study introduces a user-friendly, high efficiency data fitting program, Best Fit for Complex Peaks (BFCP), executed within Matlab®. Using XRD data as examples, we fit the integrated complex peaks by a Pseudo-Voigt function and assess the BFCP fitting ability on arbitrarily-generated complex peaks simulating XRD peaks with and without observable noise. In addition, we test BFCP with representative highly-deformed terrestrial and meteoritic samples: quartz in the Concord Granite, olivine in ureilite meteorite Larkman Nunatak 04315, and plagioclase in martian meteorite Northwest Africa 8171. We further test BFCP on Raman spectra from a plagioclase clast in martian meteorite Northwest Africa 11220. Fitting results are monitored by the Normalized Root-Mean-Squared Error (NRMSE), the sum of full width at half maximum (∑(FWHM)) and Modified-∑(FWHM). BFCP is designed for XRD data where there is contribution from both Lorentzian and Gaussian components, but it can be applied where appropriate to peak-fitting of other intensity-versus-quantity data, including spectra.

Structure and partial ordering of terrestrial kerogen: Insight from high-resolution transmission electron microscopy

Kerogen structure impacts shale gas behavior: adsorption, desorption, and diffusion. The structural partial order (the orientation and stacking extent) varies with source and maturation. The partial order of eight terrestrial kerogen samples were evaluated using high-resolution transmission electron microscopy. The fringe length, angle, and stacking distributions were quantified. For the majority of the vitrinite equivalent reflectance (VReq) range (1.1–1.9%), the aromatic structural units were similar in distribution: mainly composed of fringes of size equivalent to naphthalene, 2 × 2, and 3 × 3 rings. When the VReq was > 1.7%, there was a shift in the distribution towards the larger molecules and some fringes equivalent to 4 × 4 ring structures were present. A slight orientation was found in the sample having the lowest VReq value, with greater alignment in the VReq range 1.5–1.9% There was significantly higher alignment for the overmature samples. Stacking was limited with 92 to 99% of fringes being an individual “layer”. There was an increase in the stacking frequency with an increase of VReq > 1.8% with some stacks exceeding four layers. Thus, the increase in the structural order for the basic structural units was not uniform with maturation. There was a continuous but slight change in partial order when the reflectance was between 1.1 and 1.7% but a transition when the reflectance was ~1.8–2.0%. The transition in partial ordering from slight to more ordered was consistent with coalification jump transitions for coal maturation at Ro,m = 1.8–2.0%. These transformations are likely to impact the shale gas adsorption and its behaviors.

IUPAC-IUGS recommendation on the half-lives of 147Sm and 146Sm

The IUPAC-IUGS joint Task Group “Isotopes in Geosciences” recommends a value of (106.25 ± 0.38) Ga for the half-life of 147Sm, and a corresponding decay constant λ147 = (6.524 ± 0.024) × 10−12 a−1, both with a coverage factor k = 2. For the extinct radionuclide 146Sm two very different half-lives are used in the scientific community (c. 68 and 103 Ma), to such a degree that no consensus value can be endorsed at present by the Task Group. Pending dedicated re-investigations it is recommended that papers using the 146Sm decay to quantify the cosmo/geological evolution of (extra)terrestrial samples perform a twin set of calculations using both proposed half-lives.

Retrograde phases of former bridgmanite inclusions in superdeep diamonds

(Mg,Fe)SiO3 bridgmanite is the dominant phase in the lower mantle; however no naturally occurring samples had ever been found in terrestrial samples as it undergoes retrograde transformation to a pyroxene-type structure. To identify retrograde phases of former bridgmanite single-phase and composite inclusions of (Mg,Fe)SiO3 in a series of superdeep diamonds have been examined with electron microscopy, electron microprobe, Raman spectroscopy and X-ray diffraction techniques. Our study revealed that (Mg,Fe)SiO3 inclusions are represented by orthopyroxene. Orthopyroxenes in single-phase and composite inclusions inherit initial chemical composition of bridgmanites, including a high Al and low Ni contents. In composite inclusions they coexist with jeffbenite (ex-TAPP) and olivine. The bulk compositions of these composite inclusions are rich in Al, Ti, and Fe, which are similar but not fully resembling Al-rich bridgmanite produced in experiments on the MORB composition. The retrograde origin of composite inclusions due to decomposition of Al-rich bridgmanite may be doubtful because each of observed minerals may represent coexisting HP phases, i.e. bridgmanite or ringwoodite.