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Canyon Diablo Meteorite

What are the relative contributions of these two sources Two approaches have been taken. One is to establish the geology and hydrology of a basin in great detail. This has been carried out for the Amazon (Stallard and Edmond, 1981) with the result that evaporites contribute about twice as much sulfate as sulfide oxidation. The other approach is to apply sulfur isotope geochemistry. As mentioned earlier, there are two relatively abundant stable isotopes of S, and The mean 34/32 ratio is 0.0442. However, different source rocks have different ratios, which arise from slight differences in the reactivities of the isotopes. These deviations are expressed as a difference from a standard, in the case of sulfur the standard being a meteorite found at Canyon Diablo, Arizona. [Pg.357]

S TroiUte (FeS) from the Canyon Diablo iron meteorite V-CDT... [Pg.30]

For many years the reference standard commonly referred to is sulfur from troilite of the Canyon Diablo iron meteorite (CDT). As Beaudoin et al. (1994) have pointed out, CDT is not homogeneous and may display variations in " S up to 0.4%o. Therefore a new reference scale, Vienna-CDT or V-CDT has been introduced by an advisory committee of IAEA in 1993, recommending an artificially prepared Ag2S (IAEA-S-1) with a S Svcdt of —0.3%o as the new international standard reference material. [Pg.72]

Beaudoin G, Taylor BE (1994) High precision and spatial resolution sulfur-isotope analysis using MILES laser microprobe, Geochim Cosmochim Acta 58 5055-5063 Beaudoin G, Taylor BE, Rumble D, Thiemens M (1994) Variations in the sulfur isotope composition of troUite from the Canyon Diablo iron meteorite, Geochim Cosmochim Acta 58 4253 255... [Pg.231]

If an internal isochron cannot be generated, a model age can be determined from the measured 207pb /206Pb of the sample and the assumed initial lead isotopic ratios. For studies of the early solar system, this initial lead composition is assumed to be that measured in troilite (FeS) from the Canyon Diablo meteorite. Troilite is a uranium-free mineral and its host meteorite formed very early in the history of the solar system. Because the U/Pb ratio of the solar system is low, the lead incorporated into the troilite should not have evolved significantly from the initial composition in the solar system. [Pg.267]

The necessary atomic mobility can be provided by heating to about 1500 K (area D in Fig. 1). Various departures from ideality make it difficult to prepare pure wurtzitic carbon, even when the best graphite is used. The products obtained so far always contain some ordinary diamond as well as remnant graphite, parts of which are compressed by the nearby diamond regions. Hence, many physical properties of wurtzitic carbon are not well-known. It has been found in the Canyon Diablo meteorite and in some shock-made diamond from DuPont, but not in regular synthetic industrial diamond. This form of carbon has been given the name lonsdaleite. [Pg.565]

The mineral stishovite, Si02, was found in the Canyon Diablo meteorite. It is the form of silica formed at very high pressure. The crystal structure... [Pg.237]

Review of Isotope Concepts. The average relative concentration of the two most abundant stable isotopes of sulfur, 32S and S, are 95.0% and 4.2%, respectively. Ratios of these two isotopes are measured with specialized isotope ratio mass spectrometers, normalized to standard Canyon Diablo meteoritic sulfur, and expressed as a delta value (634S) according to the relation ... [Pg.368]

Ag2S was mixed with cuprous oxide and converted to SO2 by heating at 900 C (2). BaSC>4 was directly converted to SO2 by thermal decomposition in quartz at 1600 C (3). Product SO2 was freed from water and COo> before isotopic measurement on a Micromass 602D mass spectrometer. S/ S ratios are reported to a precision of 0.2%o relative to troilite from the Canyon Diablo meteorite using the normal 8 S%o notation. [Pg.570]

Finally, the del value is zero when the sample and the standard have the same isotopic composition. The international standards for O, C, H, N, and S are Standard Mean Ocean Water (SMOW), Pee Dee Belemnite (PDB) carbonate fossil, SMOW, atmospheric nitrogen (N2), and the Canyon Diablo Triolite (CDT) iron meteorite, respectively (table 7.6 Fame, 1986). More specifically, the13C/12C of natural materials and standards is determined using isotope-ratio mass spectrometry (for details, see Hayes, 1983 Boutton, 1991). [Pg.161]

Some meteoroids shatter upon impact, while others remain intact. Those that break when they hit the ground may be found in fragments around the site of impact. Some of these fragments may weigh a couple of tons All of the meteorites from a single fall are given the same name. Thus, the many hundreds of meteorites that have been found at Meteor Crater in Arizona are called by the name Canyon Diablo. [Pg.50]

There are four stable isotopes of sulfur as listed in Table 1. The isotopic abundances vary slightly and this is frequently used to distinguish the source of the element. Because measurement of absolute isotope abundance is difficult, relative isotopic ratios are measured by comparison with the abundance of the natural isotopes in a standard sample. The Canyon Diablo meteorite has been used as a standard for sulfur isotopes. [Pg.4506]

For stable sulphur isotopes, the standard is an iron sulphide mineral (troilite) from the Canyon Diablo meteorite. It is known as CDT (Canyon Diablo troilite) and equation 1 becomes ... [Pg.269]

The U (uranium)-Th (thorium)-Pb (lead) isotopic system represents three independent decay schemes and is a powerful but complex tool with which to unravel the history of the Earth s mantle (Text box 3.2). During planetary accretion U and Th are refractory, lithophile elements and will reside in the mantle. Pb on the other hand is a volatile and chalcophile/ siderophile element and may in part, be stored in the core. Initial U and Th concentrations are derived from chondritic meteorites, and initial Pb isotope compositions are taken from the iron-sulfide troilite phase in the Canyon Diablo meteorite. The initial bulk Earth U/Th ratio was 4.0 0.2 (Rocholl Jochum, 1993). [Pg.117]

Xenon in acid residues of iron meteorites. Murty et al. (1983) analyzed noble gases in acid-resistant residues from the Canyon Diablo and Campo del Cielo (El Taco) meteorites and found in the nonmagnetic fractions xenon that was air-like except for " Xe and Xe. The relative abundance of these isotopes is lower than in air (in which their abundance already is the lowest among well known solar system reservoirs) by up to 15%. Murty et al. (1983) suggest that this xenon may constitute presolar nebular matter which was trapped in micro-inclusions of iron meteorites. [Pg.91]

Iron meteorites and stony-irons. Reliable exposure ages for iron meteorites are often even more difficult to obtain than for stony meteorites, because quite a few iron meteorites had preatmospheric sizes of one to several meters, so that large production rate variations due to variable shielding are common. As a somewhat extreme example, He concentrations in fragments of the R -15 m Canyon Diablo meteorite vary by a factor of... [Pg.151]

Heymarm D, Lipschutz ME, Nielsen B, Anders E (1966) Canyon Diablo meteorite metallographic and mass spectrometric study of 56 fragments. J Geophys Res 71 619-641 Hidaka H, Ebihara M, Yoneda S (1999) High fluences of neutrons determined from Sm and Gd isotopic compositions in aubrites. Earth Planet Sci Lett 173 41-51 Hidaka H, Yoneda S, Nishiizumi K (2001) Neutron capture effects on Sm and Gd isotopes in Martian meteorites. Meteoritics Planet Sci 36 A80-A81... [Pg.165]

The Canyon Diablo (iron No. 34.6050, 10-20% nickel American Meteorite Laboratory see Figure 1) filings used as catalyst were extracted several times with benzene-methanol (3 1 v/v), and then carefully dried about 6 hr at 104°C (Canyon Diablo, nonoxidized). A portion of the Canyon Diablo filings was heated at red heat for several hours in air. After cooling, a small amount was retained for use as an oxidized catalyst (Canyon Diablo, oxidized). The remainder was then heated overnight... [Pg.161]

Figure I. Canyon Diablo iron No, 34,6050, American Meteorite Laboratory, The dark inclusions are nodules of graphite and troilite. Figure I. Canyon Diablo iron No, 34,6050, American Meteorite Laboratory, The dark inclusions are nodules of graphite and troilite.
Nonoxidized and oxidized-reduced Canyon Diablo meteoritic iron produced fatty acids when potassium carbonate was admixed (runs 4-97 and 4-109). The level of potassium carbonate (0.1 g vs. 0.3 g) in the catalyst (0.5 g) had no eflFect on the production of fatty acids (runs 4-109 and 5-24). Oxidized Canyon Diablo iron and potassium carbonate did not produce fatty acids (run 4-94), thus showing that promoter effects are catalyst dependent. [Pg.163]

Isotopic composition of sulphur S is determined usually by the ratio (4 stable isotopes - S, and - are known). This ratio is most stable in meteorites. That is why as standard is used the sulphur isotopic composition in troilite (FeS) from the meteorite in the Canyon Diablo Troilite (CDT) where the ratio is 1/22.22. [Pg.412]

Canyon Diablo Troilite (FeS from an iron meteorite)... [Pg.2888]


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