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Combining Lu-Hf garnet geochronology with in situ trace element analyses in garnet allowed us to gain new insight into the metamorphic evolution of UHP-UHT rocks in the Stary Gierałtów region, in the Polish Sudetes. Prograde garnet growth recorded by Rayleigh-type heavy REE (HREE) zoning in the felsic granulites indicates that the obtained 386.6 ± 4.9 Ma Lu-Hf age represents the time of

Recent developments in microspatial analysis of enamel chemistry provide the resolution needed to reconstruct detailed chronological records of an individual's early life history. Evidence of nutritional history, residential mobility, and exposure to heavy metals can potentially be retrieved from archaeological and even fossil teeth. Understanding the pattern and timing of incorporation of each trace element or stable isotope into enamel is crucial to the interpretation of the primary data. Here, we use laser ablation inductively coupled plasma mass spectrometry and ArcGIS software to map variation in calcium-normalized strontium intensities across thin sections of enamel from exfoliated deciduous teeth. Differences in calcium-normalized strontium intensities across each tooth reflect variation in tooth mineralization, implying that sampling location must be taken into account in interpreting results. Chronologically consistent shifts in calcium-normalized strontium intensities in teeth from children with known nursing histories reflect the onset and duration of breastfeeding and the introduction of nonmaternal sources of food. This tool is likely to be valuable for studying weaning and nursing behavior in the past. The distribution of normalized strontium intensities presented here is consistent with a model for the differential incorporation of strontium and calcium into enamel during the secretory and maturational phases of formation.infant diet ͉ laser ablation inductively coupled plasma mass spectrometry ͉ strontium ͉ weaning ͉ calcium A key question in paleobiology is whether it is possible to recover chronologically meaningful stable isotope or trace element distributions from tooth enamel that can be used to reconstruct age-related changes in an individual's behavior and environment during the period of enamel formation. Recently published studies show that crucially important information can potentially be retrieved in this way (1-3). Tooth enamel is a composite material with a crystalline ultrastructure and has a mineral component that closely resembles hydroxyapatite (4). The chemical constituents of hydroxyapatite are tolerant to substitution by a range of trace elements, which are readily incorporated into enamel forming at the time of exposure (5).