Introduction: Ca-, Al-rich inclusions (CAIs) from CV chondrites commonly show oxygen isotope heterogeneity among different mineral phases within individual inclusions reflecting the complex history of CAIs in both the solar nebula and/or parent bodies [1]. The degree of isotopic exchange is typically mineralspecific, yielding O-rich spinel, hibonite and pyroxene and O-depleted melilite and anor...

INTRODUCTION ..................................................................................... 504 ISOTOPE EFFECTS ........................................................................... ’ ....... 504 ISOTOPIC OMPOSITION A D DISCRIMINATION ....................................... 505 Definitions .......................................................................................... 50...

Samples of Fish Canyon and Cobb Mountain sanidine monitor standards, irradiated and fused with 7 W of CO laser 2 power for ArrAr geochronology analyses, give Pb isotope composition and Pb concentrations that are indistinguishable from unprocessed aliquots of the same monitors. The absence of measurable change in Pb isotope composition indicates the feasibility of measuring the Pb isotope compos...

The nitrogen isotope composition (δ¹⁵N) of different amino acids carries different dietary information. We hypothesized that transamination and de novo synthesis create three groups that largely explain their dietary information. Rats were fed with ¹⁵N-labeled amino acids. The redistribution of the dietary ¹⁵N labels among the muscular amino acids was analyzed. Subsequently, the labeling was ch...

The iron isotope composition of sedimentary pyrite has been proposed as a potential proxy to trace microbial metabolism and the redox evolution of the oceans. We demonstrate that Fe isotope fractionation accompanies abiotic pyrite formation in the absence of Fe(II) redox change. Combined fractionation factors between Fe(II)(aq), mackinawite, and pyrite permit the generation of pyrite with Fe is...

Water and gas samples were collected from (1) nine shallow groundwater aquifers overlying Marcellus Shale in north-central West Virginia before active shale gas drilling, (2) wells producing gas from Upper Devonian sands and Middle Devonian Marcellus Shale in southwestern Pennsylvania, (3) coal-mine water discharges in southwestern Pennsylvania, and (4) streams in southwestern Pennsylvania and ...

The aim of this study was to analyze the isotopic composition in muscle of striped weakfish Cynoscion guatucupa from Southwest Atlantic Ocean in order to evaluate a possible variation in δ13C and δ15N in response to dietary shifts that occur as animals grow. We also explored for isotopic evidence of differences between sample locations. The results showed an agreement between isotope analysis a...

Introduction: Isotopic studies of the very refractory solar condensates can potentially provide important constraints on the initial O-isotope composition of the solar nebula and its evolution [1,2]. Based on the narrow range of O-isotope composition (Δ 17 O ~ −24±2‰, 2σ) of primary minerals in FUN and non-FUN CAIs, which avoided postcrystallization isotope exchange, from CR and CV chondrites, ...

a r t i c l e i n f o Keywords: molybdenum (Mo) isotopes basaltic weathering riverine inputs estuarine mixing The application of the molybdenum (Mo) isotope system as a proxy for determining changes in the redox state of the oceans is predicated on the assumption that the composition of continental input can be characterised from crustal rock types, and remains constant. However, it has recentl...

The avian embryo resorbs most of the calcium for bone formation from the calcite eggshell but the exact mechanisms of the resorption are unknown. The present study tested whether this process results in variable fractionation of the oxygen and carbon isotopes in shell calcium carbonate, which could provide a detailed insight into the temporal and spatial use of the eggshell by the developing em...