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U-Pb ages of zircon from the Firehole and Analcite ash beds in the Eocene Green River Formation (Wyoming, United States) are indistinguishable from 40Ar/39Arages of sanidine after adjusting the latter to the astronomically calibrated age of 28.201 Ma for the Fish Canyon sanidine standard. Six of nine zircon analyses from the Firehole ash yield concordant ages in an overlapping cluster and give a weighted mean 238U-206Pb age of 51.66 ± 0.20 Ma (full external 2s uncertainty), indistinguishable from the recalibrated 40Ar/39Ar age of 51.40 ± 0.25 Ma (full external 2s uncertainty), which is adjusted to eliminate samples with low radiogenic 40Ar*. Signifi cant 238U-206Pb age scatter likely reflects some combination of minor inheritance, Pb loss, and possibly magma chamber residence. Seven of eight analyses of Analcite ash zircon yield a weighted mean 238U-206Pb age of 49.23 ± 0.13 Ma (full external 2s uncertainty), whereas the sanidine 40Ar/39Ar age is 49.24 ± 0.18 Ma (full external 2σ uncertainty). Calibrating Green River Formation 40Ar/39Ar ages to the 28.201 Ma age for Fish Canyon sanidine permits the fi rst direct comparison of specifi c Green River Formation strata to the astronomical solution for Early Eocene insolation. This comparison supports the hypothesis that periods of fl uvial deposition coincided with minima in long and short eccentricity, and that periods of lake expansion and evaporite deposition correspond to eccentricity maxima. [ABSTRACT FROM AUTHOR]

The Wooley Creek batholith is a tilted, zoned, calc-alkaline plutonic complex in the Klamath Mountains, northern California, USA. It consists of three main compositionaltemporal zones. The lower zone consists of gabbro through tonalite. Textural heterogeneities on the scale of tens to hundreds of meters combined with bulk-rock data suggest that it was assembled from numerous magma batches that did not interact extensively with one another despite the lack of sharp contacts and identical ages of two lower zone samples (U-Pb [zircon] chemical abrasion-isotope dilution-thermal ionization mass spectrometry ages of 158.99 ± 0.17 and 159.22 ± 0.10 Ma). The upper zone is slightly younger, with 3 samples yielding ages from 158.25 ± 0.46 to 158.21 ± 0.17 Ma, and is upwardly zoned from tonalite to granite. This zoning can be explained by crystalliquid separation and is related to upward increases in the proportions of interstitial K-feldspar and quartz. Porphyritic dacitic to rhyodacitic roof dikes have compositions coincident with evolved samples of the upper zone. These data indicate that the upper zone was an eruptible mush that crystallized from a nearly homogeneous parental magma that evolved primarily by upward percolation of interstitial melt. The central zone is a recharge area with variably disrupted synplutonic dikes and swarms of mafic enclaves. Central zone ages (159.01 ± 0.20 to 158.30 ± 0.16 Ma) are similar to both lower and upper zones crystallization ages. In the main part of the Wooley Creek batholith, age data constrain magmatism to a short period of time (<1.3 m.y.). However, age data cannot be used to identify distinct magma chambers within the batholith; such information must be extracted from a combination of field observations and the chemical compositions of the rocks and their constituent minerals. [ABSTRACT FROM AUTHOR]

When the complete denture population was examined for depression with the BDI, the greatest prevalence of depressive symptoms was found to coincide with the age groups that included the greatest proportion of denture wearers. An awareness by the dentist of high-risk groups for depression within the patient pool may help explain difficulties in achieving patient satisfaction with dentures, facilitate recognition of a problem, and make possible appropriate referral for diagnosis and treatment.