Germanium in Magnetite:A Preliminary Review

Magnetite is a very common mineral in various types of iron deposits and some sulfide deposits. Recent studies have focused on the use of trace elements in magnetite to discriminate ore types or trace ore-forming process. Germanium is a disperse element in the crust, but sometimes is not rare in magnetite. Germanium in magnetite can be determined by laser ablation ICP-MS due to its low detection limit（0.0X ppm）. In this study, we summary the Ge data of magnetite from magmatic deposits, iron formations, skarn deposits, iron oxide copper-gold deposits, and igneous derived hydrothermal deposits. Magnetite from iron formations contains relatively high Ge（up to ~250 ppm）, whereas those from all other deposits mostly contains Ge less than 10 ppm, indicating that iron formations can be discriminated from other Fe deposits by Ge contents. Germanium in magmatic/hydrothermal magnetite is controlled by a few factors. Primary magma/fluid composition may be the major control of Ge in magnetite. Higher oxygen fugacity may be beneficial to Ge partition into magnetite. Sulfur fugacity and temperature may have little effect on Ge in magnetite. The enrichment mechanism of Ge in magnetite from iron formations remains unknown due to the complex ore genesis. Germanium along with other elements（Mn, Ni, Ga） and element ratios（Ge/Ga and Ge/Si raios） can distinguish different types of deposits, indicating that Ge can be used as a discriminate factor like Ti and V. Because of the availability of in situ analytical technique like laser ablation ICP-MS, in situ Ge/Si ratio of magnetite can serve as a geochemical tracer and may provide new constraints on the genesis of banded iron formations.

Distinctive diet-tissue isotopic discrimination factors derived from the exclusive bamboo-eating giant panda

Stable isotope analysis is very useful in animal ecology,especially in diet reconstruction and trophic studies.Differences in isotope ratios between consumers and their diet,termed discrimination factors,are essential for studies of stable isotope ecology and are species-specific and tissue-specific.Given the specialized bamboo diet and clear foraging behavior,here,we calculated discrimination factors for carbon and nitrogen isotopes from diet to tissues(tooth enamel,hair keratin and bone collagen)for the giant panda(Ailuropoda melanoleuca),a species derived from meat-eating ancestors.Our results showed that carbon discrimination factor obtained from giant panda tooth enamel(ε^(13)C_(diet-enamel)=10.0‰)and nitrogen discrimination factors from hair keratin(Δ^(15)N_(diet-hair)=2.2‰)and bone collagen(Δ^(15)N_(diet-collagen)=2.3‰)were lower,and carbon discrimination factors from hair ker­atin(Δ^(13)C_(diet-hair)=5.0‰)and bone collagen(Δ13Cdiet-collagen=6.1‰)were higher than those of other mammalian carnivores,omnivores and herbivores.Such distinctive values are likely the result of a low-nutrient and special­ized bamboo diet,carnivore-like digestive system and exceptionally low metabolism in giant pandas.