Search NASA⌕ Search

SEARCH · Search NASA

Results for “Os(OF)2”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Possible infrared signature of decaying particles

A scenario for massive decaying particles is proposed which accounts for the detection of the submillimeter isotropic radiation component of the IR background (Matsumoto et al., 1988). The peak of the decay photon spectrum in the scenario is at several microns. The observed spectrum of the IR background is compared to that of decay photons with degraded energy. Within the limits to the radiative decays of neutrinos from gamma-ray observations os SN 1987A, it is found that the observed spectrum of decay photons is consistent with the IR background spectrum for decaying particle masses in the range between 5 and 18 keV, lifetimes in the range 2-7 X 10 to the 10th s, and a photon branching range of 0.0004 and 0.0009.

Wang, Boqi↗
NASA NTRS1971

Erlichmanite /OsS sub 2/, a new mineral.

Natural osmium disulfide (termed erlichmanite) was recognized in two occurrences on the basis of electron probe and X-ray data. One occurrence is in grains of platinum-metal sand from California, the other in a platinum-metal nugget from Western Ethiopian laterites. California erlichmanite has Os 68.0, Ir 2.6, Rh 3.8, Ru 0.4, Pd 0.5, and S 25.2, summation of 100.5 wt. %, the number of metal atoms being 1.06 on the basis of 2.00 sulfurs. Ethiopian material has higher Rh and Ir and lower Os. Both are optically isotropic. Spotty X-ray reflections from a 15-micron particle of California erlichmanite give rise to d spacing which match those of synthetic cubic osmium disulfide. Erlichmanite is defined as a cubic disulfide in which osmium is the most abundant metal atom.

Snetsinger, K. G.↗
NASA NTRS1978

Meteoritic material in lunar highland samples from the Apollo 11 and 12 sites

Radiochemical neutron activation analyses for Ag, Au, Bi, Br, Cd, Cs, Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Te, Tl, U and Zn were carried out on 11 samples from the Apollo 11 and 12 sites (two samples of rock 12013, one granitic and one KREEPy; 4 KREEP fragments from 2-4 mm soil 12033,2; 4 anorthositic fragments from 1-3 mm soil 10085,104; 1 sample of 'Luny' rock-felsite-KREEP breccia 12013 10085,31 LR-1). Most Apollo 12 samples were found to have an Imbrium meteoritic component; others, typified by the Luny breccia, apparently contain a new meteoritic component of low Re content. Components of higher Ir/Au ratio (3L, 5L and 7) were found in Apollo 11 anorthositic samples; the fact that their enrichment in meteoritic siderophiles parallels that of Fe, Mg, REE and other KREEP elements is consistent with progressive contamination of an anorthositic crust. The Luny rock was tentatively classified Group 2, supporting the assignment of this group to Serenitatis.

Janssens, M.-J.↗
NASA NTRS2011

High Pressure and Temperature Core Formation as an Alternative to the "Late Veneer" Hypothesis

The highly siderophile elements (HSE; Re, Au and the Platinum Group Elements - Pd Pt, Rh, Ru, Ir, Os) are commonly utilized to constrain accretion processes in terrestrial differentiated bodies due to their affinity for FeNi metal [1]. These eight elements exhibit highly siderophile behavior, but nonetheless have highly diverse metal-silicate partition coefficients [2]. Therefore the near chondritic relative concentrations of HSEs in the terrestrial and lunar mantles, as well as some other bodies, are attributed to late accretion rather than core formation [1]. Evaluation of competing theories, such as high pressure metal-silicate partitioning or magma ocean hypotheses has been hindered by a lack of relevant partitioning data for this group of eight elements. In particular, systematic studies isolating the effect of one variable (e.g. temperature or melt compositions) are lacking. Here we undertake new experiments on all eight elements, using Fe metal and FeO-bearing silicate melts at fixed pressure, but variable temperatures. These experiments, as well as some additional planned experiments should allow partition coefficients to be more accurately calculated or estimated at the PT conditions and compositions at which core formation is thought to have occurred.

Righter, Kevin↗
DOE OSTI2020

Materials Data on LuB4Os by Materials Project

LuOsB4 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Lu3+ is bonded in a 2-coordinate geometry to fourteen B+1.50- atoms. There are a spread of Lu–B bond distances ranging from 2.61–2.76 Å. Os3+ is bonded in a 10-coordinate geometry to ten B+1.50- atoms. There are a spread of Os–B bond distances ranging from 2.24–2.41 Å. There are four inequivalent B+1.50- sites. In the first B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Lu3+, two equivalent Os3+, and three B+1.50- atoms. There are a spread of B–B bond distances ranging from 1.74–1.87 Å. In the second B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Lu3+, two equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.84 Å. In the third B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Lu3+, two equivalent Os3+, and three B+1.50- atoms. Both B–B bond lengths are 1.73 Å. In the fourth B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to two equivalent Lu3+, four equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.73 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YB4Os by Materials Project

YOsB4 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Y3+ is bonded in a 2-coordinate geometry to fourteen B+1.50- atoms. There are a spread of Y–B bond distances ranging from 2.65–2.78 Å. Os3+ is bonded in a 10-coordinate geometry to ten B+1.50- atoms. There are a spread of Os–B bond distances ranging from 2.26–2.42 Å. There are four inequivalent B+1.50- sites. In the first B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Y3+, two equivalent Os3+, and three B+1.50- atoms. There are a spread of B–B bond distances ranging from 1.75–1.88 Å. In the second B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Y3+, two equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.85 Å. In the third B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Y3+, two equivalent Os3+, and three B+1.50- atoms. There is one shorter (1.74 Å) and one longer (1.77 Å) B–B bond length. In the fourth B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to two equivalent Y3+, four equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.72 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TmB4Os by Materials Project

TmOsB4 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Tm3+ is bonded in a 2-coordinate geometry to fourteen B+1.50- atoms. There are a spread of Tm–B bond distances ranging from 2.62–2.76 Å. Os3+ is bonded in a 10-coordinate geometry to ten B+1.50- atoms. There are a spread of Os–B bond distances ranging from 2.25–2.41 Å. There are four inequivalent B+1.50- sites. In the first B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Tm3+, two equivalent Os3+, and three B+1.50- atoms. There are a spread of B–B bond distances ranging from 1.75–1.87 Å. In the second B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Tm3+, two equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.85 Å. In the third B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Tm3+, two equivalent Os3+, and three B+1.50- atoms. There is one shorter (1.74 Å) and one longer (1.75 Å) B–B bond length. In the fourth B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to two equivalent Tm3+, four equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.72 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UB4Os by Materials Project

UOsB4 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. U4+ is bonded in a 2-coordinate geometry to fourteen B+1.50- atoms. There are a spread of U–B bond distances ranging from 2.63–2.75 Å. Os2+ is bonded in a 10-coordinate geometry to ten B+1.50- atoms. There are a spread of Os–B bond distances ranging from 2.26–2.41 Å. There are three inequivalent B+1.50- sites. In the first B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent U4+, two equivalent Os2+, and three B+1.50- atoms. There are a spread of B–B bond distances ranging from 1.74–1.89 Å. In the second B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent U4+, two equivalent Os2+, and three B+1.50- atoms. The B–B bond length is 1.76 Å. In the third B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to two equivalent U4+, four equivalent Os2+, and three B+1.50- atoms. The B–B bond length is 1.75 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuB4Os by Materials Project

PuOsB4 crystallizes in the orthorhombic Cmmm space group. The structure is three-dimensional. Pu3+ is bonded in a 2-coordinate geometry to fourteen B+1.50- atoms. There are a spread of Pu–B bond distances ranging from 2.64–2.76 Å. Os3+ is bonded in a 10-coordinate geometry to ten B+1.50- atoms. There are a spread of Os–B bond distances ranging from 2.27–2.40 Å. There are three inequivalent B+1.50- sites. In the first B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Pu3+, two equivalent Os3+, and three B+1.50- atoms. There are a spread of B–B bond distances ranging from 1.76–1.89 Å. In the second B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to four equivalent Pu3+, two equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.82 Å. In the third B+1.50- site, B+1.50- is bonded in a 9-coordinate geometry to two equivalent Pu3+, four equivalent Os3+, and three B+1.50- atoms. The B–B bond length is 1.75 Å.

36 MATERIALS SCIENCE↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Concerning Chondrites

The Lunar and Planetary Science XXXV session entitled "Concerning Chondrites" includes the following topics: 1) Petrology and Raman Spectroscopy of Shocked Phases in the Gujba CB Chondrite and the Shock History of the CB Parent Body; 2) The Relationship Between CK and CV Chondrites: A Single Parent Body Source? 3) Samples of Asteroid Surface Ponded Deposits in Chondritic Meteorites; 4) Composition and Origin of SiO2-rich Objects in Carbonaceous and Ordinary Chondrites; 5) Re-Os Systematics and HSE distribution in Tieschitz (H3.6); Two Isochrons for One Meteorite; 6) Loss of Chromium from Olivine During the Metamorphism of Chondrites; 7) Very Short Delivery Times of Meteorites After the L-Chondrite Parent Body Break-Up 480 Myr Ago; and 8) The Complex Exposure History of a Very Large L/LL5 Chondrite Shower: Queen Alexandra Range 90201.

Source record↗
DOE OSTI2021

Investigating the non-classical M-H 2 bonding in OsClH 3 (PPh 3 ) 3

Dihydrogen ligation to metal centers results in a wide range of metal-hydrogen interactions. Compounds containing non-classical dihydrogen ligands in which the H-H contacts are significantly longer than the 0.74 A distance found in solid H 2 are classified as Kubas-like compounds, stretched dihydrogen ligands, or compressed dihydrides, depending on the H-H contact length. Compounds containing stretched dihydrogen and compressed dihydride ligands are somewhat rare. Developing a more complete understanding of the metal-hydrogen and hydrogen-hydrogen interactions in these species may provide insights into the mechanisms for the oxidative addition reaction and hydrogen storage. Here, we use diffraction and inelastic neutron scattering (INS) measurements, paired with both molecular and solid-state density functional theory (DFT), to fully characterize the nature of the metal-hydrogen and hydrogen-hydrogen interactions in a previously reported compound, OsClH 3 (PPh 3 ) 3 . In that report, the H-H distance was measured as 1.48(2) A by single-crystal neutron diffraction and was described as a "stretched" dihydrogen. The INS-generated phonon density of states is well described by the DFT calculations, including those normal modes dominated by the vibrational motions of the three Os-ligated hydrogen atoms. Additionally, the resulting calculated electron charge density landscape indicates that there is no remnant bonding character between the Os-ligated hydrogen atoms in the compound. Based on these findings, we update the understanding of the metal-hydrogen bonding in this complex and reclassify it as a compressed dihydride. As such, OsClH 3 (PPh 3 ) 3 represents a rare example of a non-classical compressed dihydride species.

08 HYDROGEN↗
NASA NTRS2022

Scientific Value of Including an Atmospheric Sample as Part of Mars Sample Return (MSR)

The Perseverance rover is meant to collect samples of the martian surface for eventual return to Earth. The headspace gas present over the solid samples within the sample tubes will be of significant scientific interest for what it reveals about the interactions of the solid samples with the trapped atmosphere and for what it will reveal about the martian atmosphere itself. However, establishing the composition of the martian atmosphere will require other dedicated samples. The headspace gas as the sole atmospheric sample is problematic for many reasons. The quantity of gas present within the sample tube volume is insufficient for many investigations, and there will be exchange between solid samples, headspace gas, and tube walls. Importantly, the sample tube materials and preparation were not designed for optimal Mars atmospheric gas collection and storage as they were not sent to Mars in a degassed evacuated state and have been exposed to both Earth's and Mars' atmospheres. Additionally, there is a risk of unconstrained seal leakage in transit back to Earth, which would allow fractionation of the sample (leak-out) and contamination (leak-in). The science return can be improved significantly (and, in some cases, dramatically) by adding one or more of several strategies listed here in increasing order of effectiveness and difficulty of implementation: (1) Having Perseverance collect a gas sample in an empty sample tube, (2) Collecting gas in a newly-designed, valved, sample-tube-sized vessel that is flown on either the Sample Fetch Rover (SFR) or the Sample Retrieval Lander (SRL), (3) Adding a larger (50-100 cc) dedicated gas sampling volume to the Orbiting Sample container (OS), (4) Adding a larger (50-100 cc) dedicated gas sampling volume to the OS that can be filled with compressed martian atmosphere.

Timothy D. Swindle↗
NASA NTRS1994

Detection os X-rays from SN 1993J with ASCA

ASCA observed SN 1993J seven times between April 5 and October 24 in 1993. The 1-10 keV luminosity 10d after the explosion was (15 +/- 4) x 10(exp 39) erg/s and decreased monotonicly to (1.3 +/- 0.4) x 10(exp 39) erg/s 210 d after the explosion, when a distance of 3.6 Mpc was assumed. The hardness ratio (2-10 keV/0.5-2 keV) significantly decreased during the course of the observations. The spectrum obtained from a sky region including not only SN 1993J but also the nearby X-ray source clearly shows an iron emission line. The correlation between the iron line flux with the SN 1993J flux suggests that the iron line emission originated in SN 1993J. These observational results are discussed in the context of thermal X-ray emission from a hot region behind the shock due to the collision of the supernova ejecta with the pre-supernova stellar wind.

Kohmura, Yoshiki↗
NASA NTRS1989

Os, Sr, Nd, and Pb isotope systematics of southern African peridotite xenoliths - Implications for the chemical evolution of subcontinental mantle

Isotope analyses of Os, Sr, Nd, and Pb elements were caried out on twelve peridotite xenoliths from the Jagersfontein, Letseng-la-terae, Thaba Patsoa, Mothae, and Premier kimberlites of southern Africa, to investigate the timing and the nature of melt extraction from the continental lithosphere and its relation to the continent formation and stabilization. The distinct Os and Pb isotopic characteristics found in these samples suggested that both the low- and the high-temperature peridotites reside in an ancient stable lithospheric 'keel' to the craton that has been isolated from chemical exchange with the sublithospheric mantle for time periods in excess of 2 Ga.

Walker, R. J.↗
DOE OSTI2020

Materials Data on Te7OsO5F32 by Materials Project

OsTe7O5F32 crystallizes in the triclinic P-1 space group. The structure is zero-dimensional and consists of one OsTe7O5F32 cluster. Os8+ is bonded to five O2- and one F1- atom to form distorted OsO5F octahedra that share corners with four TeOF5 octahedra. The corner-sharing octahedra tilt angles range from 44–45°. There are a spread of Os–O bond distances ranging from 1.68–1.93 Å. The Os–F bond length is 2.18 Å. There are seven inequivalent Te+4.86+ sites. In the first Te+4.86+ site, Te+4.86+ is bonded in a 5-coordinate geometry to five F1- atoms. There are a spread of Te–F bond distances ranging from 1.87–2.44 Å. In the second Te+4.86+ site, Te+4.86+ is bonded in a 5-coordinate geometry to five F1- atoms. There are a spread of Te–F bond distances ranging from 1.87–2.58 Å. In the third Te+4.86+ site, Te+4.86+ is bonded in a 5-coordinate geometry to five F1- atoms. There are a spread of Te–F bond distances ranging from 1.87–2.63 Å. In the fourth Te+4.86+ site, Te+4.86+ is bonded to one O2- and five F1- atoms to form TeOF5 octahedra that share a cornercorner with one OsO5F octahedra. The corner-sharing octahedral tilt angles are 45°. The Te–O bond length is 1.94 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. In the fifth Te+4.86+ site, Te+4.86+ is bonded to one O2- and five F1- atoms to form TeOF5 octahedra that share a cornercorner with one OsO5F octahedra. The corner-sharing octahedral tilt angles are 44°. The Te–O bond length is 1.94 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. In the sixth Te+4.86+ site, Te+4.86+ is bonded to one O2- and five F1- atoms to form TeOF5 octahedra that share a cornercorner with one OsO5F octahedra. The corner-sharing octahedral tilt angles are 45°. The Te–O bond length is 1.93 Å. There are a spread of Te–F bond distances ranging from 1.87–1.89 Å. In the seventh Te+4.86+ site, Te+4.86+ is bonded to one O2- and five F1- atoms to form TeOF5 octahedra that share a cornercorner with one OsO5F octahedra. The corner-sharing octahedral tilt angles are 45°. The Te–O bond length is 1.94 Å. There are a spread of Te–F bond distances ranging from 1.87–1.90 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one Os8+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Os8+ and one Te+4.86+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Os8+ and one Te+4.86+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Os8+ and one Te+4.86+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Os8+ and one Te+4.86+ atom. There are thirty-two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted linear geometry to one Os8+ and one Te+4.86+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the sixth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the seventh F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the eighth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the ninth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the tenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the eleventh F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twelfth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the thirteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fourteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the fifteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the sixteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the seventeenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the eighteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the nineteenth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twentieth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-first F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-second F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-third F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-fourth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-fifth F1- site, F1- is bonded in a 1-coordinate geometry to two Te+4.86+ atoms. In the twenty-sixth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-seventh F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two Te+4.86+ atoms. In the twenty-eighth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the twenty-ninth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the thirtieth F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom. In the thirty-first F1- site, F1- is bonded in a 2-coordinate geometry to two Te+4.86+ atoms. In the thirty-second F1- site, F1- is bonded in a single-bond geometry to one Te+4.86+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS2004

Sulfide Stability of Planetary Basalts

The isotopic system, 187Re 187Os, can be used to determine the role of crust and mantle in magma genesis. In order to apply the system to natural samples, we must understand variations in Re/Os concentrations. It is thought that low [Os] and [Re] in basalts can be attributed to sulfide (FeS) saturation, as Re behaves incompatibly to high degrees of evolution until sulfide saturation occurs [1]. Previous work has shown that lunar basalts are sulfide under-saturated, and mid-ocean ridge, ocean-island and Martian (shergottites) basalts are saturated [2,3]. However, little is known about arc basalts. In this study, basaltic rocks were analyzed across the Trans-Mexican Volcanic Belt.

Caiazza, C. M.↗
NASA NTRS2003

The Disposition of Pt, Pd, Ir, Os, and Ru in Marine Sediments and the K/T Boundary

The marine record of platinum group elements (PGEs) and Os isotopic compositions provides information on different inputs of PGEs into the oceans. Some studies based on a smaller subset of the PGEs suggest that the PGEs may suffer post-depositional mobility during diagenesis. In some K/T boundary clays, Kyte and others showed that the relative abundances of Pt, Pd, Ir, and Os can differ significantly from chondritic, which is the signature expected from fallout of the meteorite impact. In some K/T boundary sections, elevated Ir concentrations are observed as far as 1 meter from the cm-thick boundary clay containing the meteoritic ejecta. The purpose of this study was to characterize Pt, Pd, Ir, Os, and Ru abundances in zones including the K/T boundary. We determined PGE abundances of boundary clays at two hemipelagic sites (Stevns Klint, Denmark and Caravaca, Spain) in which previous studies by Kyte and others showed that the Ir anomaly is confined to within a few cm. We also analyzed two pelagic Pacific sites: a boundary clay from the north Pacific (Hole 465A) characterized by a 0.5 m thick Ir anomaly and a transect across the K/T boundary from the south Pacific (Hole 596) where the Ir anomaly spans 2 m. The Stevns Klint, Caravaca, and north Pacific sites are characterized by abundant marls and limestones in the section, whereas the south Pacific site is dominated by clays. Samples were spiked with isotopic tracers, mixed with a flux, S and Ni, and equilibrated by fusion. PGEs were extracted from the Ni and analyzed on a Finnigan Element ICP-MS. We find that the narrow Caravaca and Stevns Klint boundary clays have relative PGE abundance patterns indistinguishable from chondritic values. The two Pacific sites were found to have nearly identical PGE patterns but have ratios at the peak, which differ from chondritic values as found earlier by Evans et al. The Pacific sites were found to have nearly identical PGE patterns but are extremely depleted in OS (Os/Ir = 0.07-0.15) and slightly enriched in Pd and Pt relative to Ir.

Lee, Cin-Ty↗