We apply the carbonate clumped isotope thermometer (D47) to macrofossils from the Baculites compressus ( 73.5 Ma) and the Hoploscaphites nebrascensis ( 67 Ma) ammonite zones of the Western Interior Seaway (WIS) of North America, and nearby coeval terrestrial and open marine environments. The carbonate clumped isotope thermometer is based on a single-phase isotope exchange equilibrium that promo...

Study of commercially produced volcanic CO2 gas associated with the Colorado Plateau, USA, has revealed substantial new information about the noble gas isotopic composition and elemental abundance pattern of the mantle. Combined with published data from mid-ocean ridge basalts, it is now clear that the convecting mantle has a maximum (20)Ne/(22)Ne isotopic composition, indistinguishable from th...

The mechanistic understanding of isotope fractionation processes is increasing but we still lack detailed knowledge of the processes that determine the isotopic composition of the tree-ring archive over the long term. Especially with regard to the path from leaf photosynthate production to wood formation, post-assimilation fractionations/processes might cause at least a partial decoupling betwe...

Recent isotopic observations of animal samples indicate body accumulation of heavy zinc and light copper throughout life. This hypothesis has never been tested for humans, but the existence of a relationship between blood isotopic composition and age could be promising for age assessment methodologies. Dietary habits can also influence the blood zinc isotope composition, being an additional sou...

Introduction: Interplanetary dust particles (IDPs) are composed of a variety of primitive materials and are the repositories of various isotopic anomalies. They are well known to exhibit enrichments of deuterium (D) and N [e.g., 1-3], although the two types of isotopic anomalies do not appear to be directly correlated. The enrichments are generally thought to be carried by organic compounds [4-...

[1] The oxygen isotope content of nocturnal ecosystem respiration (dOR) was examined in forests along a precipitation gradient in Oregon, USA, to determine whether site-to-site variation in dOR was more strongly related to variation in d O of precipitation or to evaporative processes that isotopically modify water pools within ecosystems. Measurements were made over 4 years at sites ranging in ...

The Pb isotopic compositions of maskelynite and pyroxene grains were measured in ALH84001 and three enriched shergottites (Zagami, Roberts Massif 04262, and Larkman Nunatuk 12011) by secondary ion mass spectrometry. A maskelynite-pyroxene isochron for ALH84001 defines a crystallization age of 4089 ± 73Ma (2σ). The initial Pb isotopic composition of each meteorite was measured in multiple maskel...

-We assess the utility of four species of living planktonic foraminifera as tracers of thermocline and intermediate water masses in the northern Pacific Ocean, based on their water-column distribution and shell isotopic composition. Assuming oxygen isotopic equilibria with the water column, we infer apparent calcification depths. This allows an estimate of apparent carbon isotopic disequilibria...

Oxygen and carbon isotopic compositions of ambient carbon dioxide in two tropical forests in the Amazonian basin were determined at the beginning and the end of the dry season. One site, Fazenda Vitoria, is typical of a seasonal forest with a pronounced dry season from May to November whereas the other site, Reserva Ducke, has a milder dry season. Samples collected at night revealed that in the...

Marine Protected Areas (MPAs) are often established to mitigate the effects of overfishing and other human disturbances. In Fiji these are locally managed and, where enforced, have significantly higher coral cover, higher fish biomass, and lower seaweed cover than in the adjacent, unprotected reefs (non-MPAs). We investigated how the isotopic signatures of a common, mid-level consumer, Epinephe...