The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
G J S J Consolmagno - One of the best experts on this subject based on the ideXlab platform.
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the measurement of Meteorite heat capacity at low temperatures using liquid nitrogen vaporization
Planetary and Space Science, 2013Co-Authors: G J S J Consolmagno, D T Britt, Martha W Schaefer, Bradley E Schaefer, Robert J Macke, M C Nolan, E S HowellAbstract:Abstract Meteorite heat capacity (specific heat) is an essential parameter in modeling many aspects of the orbital and internal evolution of small solar system bodies, and can be a tool for characterization of the material in a Meteorite itself. We have devised a novel method for the measurement of this quantity in whole-rock samples of Meteorites, at low temperatures typical of asteroids. We insert the sample in liquid nitrogen, measure the mass of nitrogen boiled off due to the heat within the sample, and calibrating against measurements of pure quartz with a temperature-averaged heat capacity of 494 J/kg K we calculate the temperature-average heat capacity of the sample. We show that this method is accurate, rapid, inexpensive, and non-destructive. Preliminary results for chondrites and metal rich Meteorites are in excellent agreement with the literature data for Meteorites, and hold the promise that such measurements may not only produce values useful to modelers but they also may provide an efficient way to classify whole Meteorite samples and characterize subtle differences between Meteorites of different compositional classes.
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stony Meteorite porosities and densities a review of the data through 2001
Meteoritics & Planetary Science, 2003Co-Authors: D T Britt, G J S J ConsolmagnoAbstract:In this review, we summarize the data published up to December 2001 on the porosity and density of stony Meteorites. These data were taken from 925 samples of 454 different Meteorites by a variety of techniques. Most Meteorites have densities on the order of 3 to 4 g/cm^3, with lower densities only for some volatile-rich carbonaceous Meteorites and higher densities for stony irons. For the vast majority of stones, porosity data alone cannot distinguish between different Meteorite compositions. Average porosities for most Meteorite classes are around 10%, though individual samples can range as high as 30% porosity. Unbrecciated basaltic achondrites appear to be systematically less porous unless vesicles are present. The measured density of ordinary chondrites is strongly controlled by the amount of terrestrial weathering the sample has undergone with porosities steadily dropping with exposure to the terrestrial environment. A theoretical grain density based on composition can model "pre-weathered" porosities. The average model porosity for H and LL chondrites is 10%, while L chondrite model porosities average only 6%, a statistically significant difference.
S F Wolf - One of the best experts on this subject based on the ideXlab platform.
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labile trace elements in basaltic achondrites can they distinguish between Meteorites from the moon mars and v type asteroids
Meteoritics & Planetary Science, 2009Co-Authors: S F Wolf, Mingsheng Wang, Michael E LipschutzAbstract:We report data for 14 mainly labile trace elements (Ag, Au, Bi, Cd, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn) in eight whole-rock lunar Meteorites (Asuka [A-] 881757, Dar al Gani [DaG] 262, Elephant Moraine [EET] 87521, Queen Alexandra Range [QUE] 93069, QUE 94269, QUE 94281, Yamato [Y-] 793169, and Y-981031), and Martian Meteorite (DaG 476) and incorporate these into a comparative study of basaltic Meteorites from the Moon, Mars, and V-type asteroids. Multivariate cluster analysis of data for these elements in 14 lunar, 13 Martian, and 34 howardite, eucrite, and diogenite (HED) Meteorites demonstrate that materials from these three parents are distinguishable using these markers of late, low-temperature episodes. This distinguishability is essentially as complete as that based on markers of high-temperature igneous processes. Concentrations of these elements in 14 lunar Meteorites are essentially lognormally distributed and generally more homogeneous than in Martian and HED Meteorites. Mean siderophile and labile element concentrations in the 14 lunar Meteorites indicate the presence of a CI-equivalent microMeteorite admixture of 2.6%. When only feldspathic samples are considered, our data show a slightly higher value of 3.4% consistent with an increasing microMeteorite content in regolith samples of higher maturity. Concentrations of labile elements in the 8 feldspathic samples hint at the presence of a fractionated highly labile element component, possibly volcanic in origin, at a level comparable to the microMeteorite component. Apparently, the process(es) that contributed to establishing lunar Meteorite siderophile and labile trace element contents occurred in a system open to highly labile element transport.
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determination of cosmochemically volatile trace elements in chondritic Meteorites by inductively coupled plasma mass spectrometry
Analytica Chimica Acta, 2005Co-Authors: S F Wolf, Derick L Unger, J M FriedrichAbstract:Abstract We have developed a method for the quantification of 14 cosmochemically moderately volatile to highly volatile trace elements (Cu, Zn, Ga, Se, Rb, Ag, Cd, In, Sn, Sb, Te, Cs, Tl, and Bi) in chondritic Meteorites by ICPMS. The method utilizes internal standardization via addition of Be, Rh, Re, and U and multiple single point matrix-matched external calibrations with Allende standard reference Meteorite to provide drift corrected calibration within an ICPMS procedure. We have demonstrated our method's precision and accuracy by performing replicate dissolutions and analyses of 0.05–0.10 g samples of a homogenized sample of the CM2 Murchison Meteorite and compared our results to literature values for this Meteorite. Our procedure allows for a rapid and accurate determination of the cosmochemically important VTEs in chondritic Meteorites providing the means for an even more comprehensive elemental analysis of a single sample of chondritic material.
D T Britt - One of the best experts on this subject based on the ideXlab platform.
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the measurement of Meteorite heat capacity at low temperatures using liquid nitrogen vaporization
Planetary and Space Science, 2013Co-Authors: G J S J Consolmagno, D T Britt, Martha W Schaefer, Bradley E Schaefer, Robert J Macke, M C Nolan, E S HowellAbstract:Abstract Meteorite heat capacity (specific heat) is an essential parameter in modeling many aspects of the orbital and internal evolution of small solar system bodies, and can be a tool for characterization of the material in a Meteorite itself. We have devised a novel method for the measurement of this quantity in whole-rock samples of Meteorites, at low temperatures typical of asteroids. We insert the sample in liquid nitrogen, measure the mass of nitrogen boiled off due to the heat within the sample, and calibrating against measurements of pure quartz with a temperature-averaged heat capacity of 494 J/kg K we calculate the temperature-average heat capacity of the sample. We show that this method is accurate, rapid, inexpensive, and non-destructive. Preliminary results for chondrites and metal rich Meteorites are in excellent agreement with the literature data for Meteorites, and hold the promise that such measurements may not only produce values useful to modelers but they also may provide an efficient way to classify whole Meteorite samples and characterize subtle differences between Meteorites of different compositional classes.
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stony Meteorite porosities and densities a review of the data through 2001
Meteoritics & Planetary Science, 2003Co-Authors: D T Britt, G J S J ConsolmagnoAbstract:In this review, we summarize the data published up to December 2001 on the porosity and density of stony Meteorites. These data were taken from 925 samples of 454 different Meteorites by a variety of techniques. Most Meteorites have densities on the order of 3 to 4 g/cm^3, with lower densities only for some volatile-rich carbonaceous Meteorites and higher densities for stony irons. For the vast majority of stones, porosity data alone cannot distinguish between different Meteorite compositions. Average porosities for most Meteorite classes are around 10%, though individual samples can range as high as 30% porosity. Unbrecciated basaltic achondrites appear to be systematically less porous unless vesicles are present. The measured density of ordinary chondrites is strongly controlled by the amount of terrestrial weathering the sample has undergone with porosities steadily dropping with exposure to the terrestrial environment. A theoretical grain density based on composition can model "pre-weathered" porosities. The average model porosity for H and LL chondrites is 10%, while L chondrite model porosities average only 6%, a statistically significant difference.
Yoram Teitler - One of the best experts on this subject based on the ideXlab platform.
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effective radium 226 concentration in Meteorites
Geochimica et Cosmochimica Acta, 2017Co-Authors: Frédéric Girault, Frédéric Perrier, Manuel Moreira, Brigitte Zanda, Pierre Rochette, Yoram TeitlerAbstract:The analysis of noble gases in Meteorites provides constraints on the early solar system and the pre-solar nebula. This requires a better characterization and understanding of the capture, production, and release of noble gases in Meteorites. The knowledge of transfer properties of noble gases for each individual Meteorite could benefit from using radon-222, radioactive daughter of radium-226. The radon-222 emanating power is commonly quantified by the effective radium-226 concentration (ECRa), the product of the bulk radium-226 concentration and of the emanation coefficient E, which represents the probability of one decaying radium-226 to inject one radon-222 into the free porous network. Owing to a non-destructive, high-sensitivity accumulation method based on long photomultiplier counting sessions, we are now able to measure ECRa of Meteorite samples, which usually have mass smaller than 15 g and ECRa < 0.5 Bq kg−1. We report here the results obtained from 41 different Meteorites, based on 129 measurements on 70 samples using two variants of our method, showing satisfactory repeatability and a detection limit below 10−2 Bq kg−1 for a sample mass of 1 g. While two Meteorites remain below detection level, we obtain for 39 Meteorites heterogeneous ECRa values with mean (min–max range) of ca. 0.1 (0.018–1.30) Bq kg−1. Carbonaceous chondrites exhibit the largest ECRa values and eucrites the smallest. Such values are smaller than typical values from most terrestrial rocks, but comparable with those from Archean rocks (mean of ca. 0.18 Bq kg−1), an end-member of terrestrial rocks. Using uranium concentration from the literature, E is inferred from ECRa for all the Meteorite samples. Values of E for Meteorites (mean 40 ± 4%) are higher than E values for Archean rocks and reported values for lunar and Martian soils. Exceptionally large E values likely suggest that the 238U-226Ra pair would not be at equilibrium in most Meteorites and that uranium and/or radium are most likely not uniformly distributed. ECRa of Meteorites is correlated with E and seems to mainly reflect the gas permeability of the Meteorite, which could be one important property, preserved in the Meteorite, of its parent body, characterizing its history in space, possibly modified by alteration, shock metamorphism, and eventually weathering on Earth. Larger radon emanation values are associated with larger concentrations of the heaviest noble gases (argon, krypton, xenon), and larger 20Ne/22Ne and 36Ar/38Ar ratios, suggesting Earth’s atmosphere contamination or solar wind implantation, and probably a similar carrier phase such as Q phase. An unclear correlation is observed with 40Ar, which may rule out a purely radiogenic effect on radon emanation. Thus, larger radon emanation suggests a larger capacity of collecting solar and terrestrial gases, which should imply higher loss of gases generated in the Meteorite and larger dispersion of Pb/U ratios for age determination. This study provides the first quantification of natural radon-222 loss from Meteorites and opens promising perspectives to quantify the relationship between pore space connectivity and the transfer properties for noble gases in Meteorites and other extraterrestrial bodies.
Jeff Wynn - One of the best experts on this subject based on the ideXlab platform.
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luminescence dating of the wabar Meteorite craters saudi arabia
Journal of Geophysical Research, 2004Co-Authors: J R Prescott, G B Robertson, C Shoemaker, E M Shoemaker, Jeff WynnAbstract:[1] Luminescence dating has been used to find the age of Meteorite impact craters at Wabar (Al Hadida) in Saudi Arabia. The luminescence characteristics of the shocked material were determined. Using a variety of luminescence dating techniques applied to impactite formed by the Meteorite, and to the underlying sand, the age is found to be 290 ± 38 years. A comparison is made with two possible historically recorded ages. An impact as young as this has implications for the assessment of hazards from the impact on Earth of small Meteorites.
