نتایج جستجو برای: isotopic composition
تعداد نتایج: 273380 فیلتر نتایج به سال:
Finding direct evidence for atmospheric circulation change in terrestrial records of Holocene climate variability remains a fundamental challenge. Here we present the first combined stable oxygen and hydrogen isotopic palaeorecord from a peatland core in Newfoundland, Canada. Sphagnum cellulose samples were isolated from a core from Nordan’s Pond Bog, Newfoundland, and analysed for dD values. C...
Title of Document: The Multiple Sulfur Isotopic Composition of Iron Meteorites: Implications for Nebular Evolution. Michael Ariel Antonelli, Master of Science, 2013. Directed By: Professor James Farquhar, Department of Geology and Earth System Sciences Interdisciplinary Center, University of MarylandCollege Park Multiple sulfur isotopic measurements of troilite from 61 different iron meteorites...
Pristine meteoritic materials carry light element isotopic fractionations that constrain physiochemical conditions during solar system formation. Here we report the discovery of a unique xenolith in the metal-rich chondrite Isheyevo. Its fine-grained, highly pristine mineralogy has similarity with interplanetary dust particles (IDPs), but the volume of the xenolith is more than 30,000 times tha...
Meteorite studies suggest that each solar system object has a unique oxygen isotopic composition. Chondrites, the most primitive of meteorites, have been believed to be derived from asteroids, but oxygen isotopic compositions of asteroids themselves have not been established. We measured, using secondary ion mass spectrometry, oxygen isotopic compositions of rock particles from asteroid 25143 I...
Isotopic effects occuring during the evaporation of microgram quantities of chemically pure rubidium, potassium and lithium compounds are studied. The measured isotopic ratios show a time dependent variation corresponding to a RAYLEIGH distillation. The fractionation factor is equal to the square root of the ratio of the masses. The highest observed enrichments are 45% for lithium, 10% for pota...
The isotopic composition of fossil fuels is an important component of many studies of C sources and sinks based on atmospheric measurements of CO2. In C budget studies, the isotopic composition of crude petroleum and CH4 are often used as a proxy for the isotopic composition of CO2 emissions from combustion. In this study, the C isotope composition (dC) of exhaust from the major fossil fuel emi...
Introduction: The Sun includes 99.9% of the mass of the solar system, so analysis of the isotopic compositions of elements from the Sun should be representative of the initial and/or bulk isotopic composition of planetary materials. Gravitational settling from the Outer Convection Zone (OCZ) of the Sun may contribute towards systematic light isotope enrichment of a few per mil detectable in the...
and Karl-Ludwig Kratz, Department of Physics, University of Notre Dame, Notre Dame, IN 46556, USA, Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel ([email protected]), Max-PlanckInstitut für Chemie (Otto-Hahn-Institut), D-55128 Mainz, Germany Introduction The rare presolar SiC grains from supernovae (SNe), called SiC of type X, make up only ∼ 1% of all pr...
Introduction: Calcium-aluminum-rich inclusions (CAIs) from the metal-rich (CH/CB-like) carbonaceous chondrite Ish-eyevo are mineralogically pristine and show no evidence for postcrystallization alteration [1]. Many of them are composed of very refractory minerals, such as hibonite (CaAl 12 O 19), grossite (CaAl 4 O 7), aluminum-rich pyroxene, and perovskite (CaTiO 3). We will present oxygen iso...
We investigate the origin of archaeological wool textiles preserved by anoxic waterlogging from seven medieval archaeological deposits in north-western Europe (c. 700-1600 AD), using geospatial patterning in carbon (δ13C), nitrogen (δ15N) and non-exchangeable hydrogen (δ2H) composition of modern and ancient sheep proteins. δ13C, δ15N and δ2H values from archaeological wool keratin (n = 83) and ...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید