Nickel isotope abundances of type I deep-sea spheres and of iron-nickel spherules from sediments in Alberta, Canada

Isotopic compositions of oxygen, iron, chromium, and nickel in cosmic spherules: Toward a better comprehension of atmospheric entry heating effects

“…In general, the ranges and absolute values of ⌽ calculated for Cr, Fe, and Ni resemble those reported by others (Davis and Brownlee, 1993;Xue et al, 1995;Herzog et al, 1999). We confirm the tendency of ⌽ Ni to increase as Ni content decreases, as expected from a well mixed evaporating system of relatively uniform starting composition (Fig.…”

“…Values of ⌽ Ni, a quantity that measures the degree of mass dependent fractionation of Ni, anticorrelate with Ni content (bottom X-axis), suggesting that the precursor particles have a limited compositional range. Literature values are from Davis and Brownlee (1993) and Xue et al (1995). The theoretical Rayleigh distillation behavior showing the values of ⌽ Ni expected as a function of the retained fraction of Ni (top X-axis) is given for comparison (dotted line).…”

Internal structure of type I deep-sea spherules by X-ray computed microtomography

“…Most of the spherules that were tomographed do not contain large (>10 µm in diameter) metallic cores. The inferred scarcity of metallic cores is somewhat surprising but is consistent with the results of Xue et al (1995) and BontÈ et al (1987), who studied other objects from the KK collection.…”

Spherules with pure iron cores from Myanmar jadeitite: Type-I deep-sea spherules?

“…The Myanmar spherules have low Ni concentrations of less than 1.0 wt.%, lower than most type-I cosmic spherules (Herzog et al, 1999;Basu et al, 2003;Gounelle et al, 2003;Taylor et al, 2005), but similar to some minor type-I cosmic spherules containing iron cores with very low nickel contents. The Ni-poor spherules could be from pre-existing metal and sulfide, or produced by the reduction of low-Ni sulfide or silicates in the interior of the decelerating object, in such cases the droplet begins to cool before appreciable Rayleigh fractionation takes place (e.g., Xue et al, 1995;Herzog et al, 1999). Other supportive evidence includes the existence of pure iron nuggets from chondritic meteorites that lack obvious fractionation and enrichment process (Miono et al, 1999).…”