Apatite u thhe dating
Nov 8, 2011 - Abstract: Chemical composition, antioxidant and antimicrobial .... In addition, all the apatite grains are ﬂuorapatites with F contents of 1.58–2.54 wt.% and Cl contents of 0.57–0.88 wt.%.
natural insecticides as well as in the perfumery industries , while ..... These grains are enriched in REEs (∑REE = 3341–5527 ppm) with signiﬁcant Eu anomalies (Eu/Eu∗ = 0.20–0.24), low Sr/Y radios (0.20–0.35), high 87Sr/86Sr ratios (range from 0.70635 to 0.70697).
The quadrupole He mass spectrometry systems consist of the following principle components: 1) One Photonmachine 30W Diode Laser and two Photonmachine 75W Diode lasers and a U. Laser continuous-mode Nd-YAG lasers for total fusion He laser extraction, ideal for single-crystal work (see House et al., 2000), 2) two separate all-metal extraction lines equipped with computer-controlled pneumatic Nupro valves and pumped by a combination of ion, turbo and rough pumps, 3) precise volume aliquot systems for spiking sample gas with 3He for isotope dilution, 4) precise volume aliquot systems for delivering a 4He standard with separate depletion tank systems to monitor 4He tank depletion, 5) gas purification system consisting of two SAES NP10 getters and two Janis cryogenic trap capable of separating He from other gases by variable temperature release at 16-37K, and 6) two Blazers Prisma QMS-200 quadrupole mass spectrometer for measuring 3He/4He ratios.
Our helium isotope dilution procedure allows very low-blank ( *reference age is published (U-Th)/He age; sample used by several laboratories as intra- and inter-laboratory age standard.
These factors contribute to substantially higher analytical imprecision for most LADD U/Pb dates for apatite, occasionally too high for the dates to be geologically useful.Sixty-two laser-ablation analyses of a single large crystal of Durango fluorapatite yielded an inverse-variance weighted mean U date of 31.46 ± 0.48 Ma and an inverse-variance weighted mean (U-Th-Sm)/He date of 31.75 ± 0.60 Ma, both of which are in good agreement with previously published conventional dates.