Epithermal Fluorite Deposits in Transbaikalia (Geochemical Features, Sources of Matter and Fluids, and Genesis)

—We consider the isotope-geochemical features of epithermal fluorite deposits in Transbaikalia, including the REE compositions, Sr isotope ratios, Sm–Nd systems, and isotope compositions of oxygen, carbon, hydrogen, and sulfur. The 87Sr/86Sr ratios in fluorites are within 0.706–0.708, and the εNd values are negative. Oxygen in quartz, the main mineral of the deposits, has a light isotope composition (δ18O = –3.4 to +2.6‰), and the calculated isotope composition of oxygen in the fluid in equilibrium with quartz (δ18O = –9 to –16‰) indicates the presence of meteoric water. The latter is confirmed by analysis of the isotope compositions of oxygen and hydrogen in gas–liquid inclusions in fluorites from three deposits. These isotope compositions are due to recycling caused by the impact of shallow basic plutons. The isotope composition of sulfur indicates its deep source. During ascent, sulfur became enriched in its light isotope (δ34S = –1.8 to –7.7‰). We assess the association of fluorite ores with basaltoids widespread in the study area. The isotope and geochemical parameters suggest their spatial proximity. Probably, the basaltoids were responsible for the recycling of meteoric water. It is shown that the epithermal fluorite deposits formed by the same mechanism as fissure–vein thermal waters in western Transbaikalia.

Middle Palaeolithic Diets

This chapter examines the evidence for diet amongst Middle Palaeolithic foragers in Europe and south-west Asia from c. 300,000 to 40,000 years ago, concentrating on faunal and isotopic approaches. Published faunal evidence shows that Middle Palaeolithic hominins in both regions hunted a relatively narrow range of medium- to large-sized ungulates, with occasional exploitation of megaherbivores more evident in open sites than in caves and rockshelters. Broader diets have been documented in southern Europe, although regular consumption of fast, small-sized taxa emerged only later during the Upper Palaeolithic. Stable light isotope data, often interpreted as indicating that European Neanderthals were top-level predators preferring either megaherbivores, or bovids and horses, only partly accords with the faunal evidence. Taphonomic considerations suggest that energy procurement, especially as fat, and the effects of transport constraints have so far not been sufficiently considered when assessing the dietary composition of Middle Palaeolithic hominins.