The triple oxygen isotope composition of Precambrian chert

Oxygen Isotope Composition of Seawater

Oxygen isotope composition of the primitive Achondrites

Introduction: Primitive achondrites are meteorites with near-chondritic bulk compositions and nonchondritic textures [1]. They are thought to be either highly metamorphosed chondrites, or residues formed by low degrees of partial melting [1]. They thus record the conditions at the onset of asteroidal melting and form an important link between chondrites and the extensively melted achondrites (i...

Unexpected variations in the triple oxygen isotope composition of stratospheric carbon dioxide.

We report observations of stratospheric CO2 that reveal surprisingly large anomalous enrichments in (17)O that vary systematically with latitude, altitude, and season. The triple isotope slopes reached 1.95 ± 0.05(1σ) in the middle stratosphere and 2.22 ± 0.07 in the Arctic vortex versus 1.71 ± 0.03 from previous observations and a remarkable factor of 4 larger than the mass-dependent value of ...

Triple oxygen isotope variations in sedimentary rocks

Relatively large (P0.2&) O anomalies in the geologic record have been used to recognize atmospheric processes such as photochemical reactions and to trace changes in the partial pressures of O2 and CO2 in Earth’s atmosphere through time. However, recent oxygen isotope measurements of terrestrial rocks, minerals and waters also reveal common, smaller (but statistically significant) deviations fr...

Ambient pyrite in precambrian chert: new evidence and a theory.

Ambient pyrites of two distinct types were described from middle Precambrian rocks of the Lake Superior area. A new class of this phenomenon is here described from middle Precambrian chert from western Australia. The newly found ambient pyrites are quite minute and characteristically occur in groups forming a "starburst" pattern. All three types of ambient pyrite may be explained in terms of pr...