Preparative high pressure liquid chromatography on US-Y zeolite shape-selective molecular sieve was studied for carbon isotopic fractionation e€ects. We tested a standard mixture [17b, 21b(H)-hopane, 5a-cholestane] and complex natural hydrocarbon mixtures dominated by tetraand pentacyclic triterpenoids extracted from Oxford Clay shales. We con®rmed that steroids and hopanoids were separated on ...

Introduction Ocean island basalts (OIB) are thought to sample the Earth’s deep mantle, whereby thermochemical plumes entrain lower mantle material and bring it to the surface where it erupts. By measuring the isotopic compositions of global OIB—which record the isotopic compositions of OIB mantle sources—geochemists can “map” the isotopic heterogeneity of the Earth’s deep mantle (e.g., Gast et ...

We present a new event-scale catalog of stable isotopic measurements from 5 years of storm events at 4 sites in southern California, which is used to understand the storm to storm controls on the isotopic composition of precipitation and validate the event-scale performance of an isotope-enabled GCM simulation (IsoGSM) (Yoshimura et al. 2008). These analyses are motivated to improve the interpr...

Carbonatites are mantle-derived, intraplate magmas that provide a means of documenting isotopic variations of the Earth's mantle through time. To investigate the secular Li isotopic evolution of the mantle and to test whether Li isotopes document systematic recycling of material processed at or near the Earth's surface into the mantle, we analyzed the Li isotopic compositions of carbonatites an...

During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different e...

Barium isotopic compositions of primitive materials in the solar system are generally affected by s- and r-process nucleosynthetic components that hide the contribution of the isotopic excess of (135)Ba formed by decay of radioactive (135)Cs. However, the Ba isotopic composition of the chemical separates from chondrules in the Sayama CM2 chondrite shows an excess of (135)Ba isotopic abundance u...

Presolar grains are considered to have traces in their birth before the solar system formation in their isotopic and elemental features. Most of silicon carbide type X (SiC X) and low density graphite grains show the excesses of 12C and 28Si. These isotopic features suggest that SiC X and low density graphite are originating from supernovae. On the other hand, elemental signatures of the grains...

Generalization of the Lorentz invariance based on Lie-isotopic approach is considered. Lie-isotopy permits metric tensor to be more general than the Minkowski one in a way that it may depend on local variables, the inverse of it being the unit of the associated Lie-isotopic algebra. The problem of specific Lie-isotopic liftings, which may be realized in various ways, is discussed.

High-precision iron isotopic compositions for Fe-bearing geological reference materials and chondrites with a wide range of matrices (e.g., silicates, oxides, organic-bearing materials) are reported. This comprehensive data set should serve as a reference for iron isotopic studies across a range of geological and biological disciplines for both quality assurance and inter-laboratory calibration...

Calcium from bone and shell is isotopically lighter than calcium of soft tissue from the same organism and isotopically lighter than source (dietary) calcium. When measured as the (44)Ca/(40)Ca isotopic ratio, the total range of variation observed is 5.5 per thousand, and as much as 4 per thousand variation is found in a single organism. The observed intraorganismal calcium isotopic variations ...