Search results for "Elemental distribution"
showing 2 items of 2 documents
Refractory metal nuggets in different types of cosmic spherules
2014
Abstract Out of the three basic cosmic spherule types collected from the seafloor, RMNs (refractory metal nuggets) have been reported from I-type spherules commonly, rarely from S-type spherules and never from the G-type spherules. Nuggets in the I-type cosmic spherules have formed by melting and complete oxidation during atmospheric entry, whereas no clear understanding emerged so far regarding the formation of the rare nuggets in S-type spherules. We collected cosmic spherules by raking the deep seafloor with magnets, and carried out systematic and sequential grinding, polishing and electron microscopic investigations on 992 cosmic spherules to identify RMNs. Fifty-four nuggets (RMNs) are…
Assessment of the mechanism of elemental incorporation into bivalve shells (Arctica islandica) based on elemental distribution at the microstructural…
2014
Abstract To address the mechanism of elemental incorporation into shells of the bivalve Arctica islandica , we performed two-dimensional elemental mapping of Sr, Mg, and S at a ∼3 μm spatial resolution using electron microprobe. These elemental distributions were precisely compared to the shell microstructure. The Sr distribution was intimately linked to the S concentration and/or shell microstructure. Sr showed a clear annual pattern with higher values at the annual growth lines and lower values in annual growth increments. The Sr and S concentrations were higher near sub-annual growth lines than in the adjacent regions, which were dominated by acicular microstructure (middle shell layer) …