This page is based on a Wikipedia article written by contributors (read/edit).Text is available under the CC BY-SA 4.0 license; additional terms may apply.Comparable shifts to full glacial environments on the continents are documented in pollen bearing deposits and in the loess sequences and at the outset of the temperate Odderade interstadial and its correlatives which are dated by C determinations on peats older than 50,000 yr have to be understood as minimum ages. The measured ages are interpreted as the sedimentation ages of the coal tonsteins and tuffs.The isotopes the KAr system relies on are Potassium (K) and Argon (Ar).
The accuracy of the system has been examined and confirmed by the analyses of some reference materials, such as SORI93 biotite (K-Ar age: 92.6 ± 0.6 Ma; Sudo et al., 1998) or HD-B1 biotite (K-Ar age: 24.21 ± 0.32 Ma; Hess & Lippolt, 1994), shown in the figures below.
In broader terms, the results mandate a re-evaluation of the astronomically calibrated ages for these and other sanidine samples, while the new generation of multi-collector mass spectrometers provides the means to further evaluate 40Ar/39Ar ages used to define new decay constants and standard ages.
The J value is a combined parameter incorporating the conditions of the neutron irradiation and which is obtained from simultaneously irradiated standard mineral samples of known age.
Due to the long half life of 1.25 x 10Ar dating system (see photo at the top of this page) includes: (1) a Micromass 5400 high sensitivity-low background sector-type noble gas mass spectrometer, (2) a New Wave Research Dual Wave laser system comprising a CO continuous laser and an UV pulsed laser, and (3) a ultra-high vacuum metal purification line which includes Zr-Al SAES alloy getters and a cold trap.
Masafumi Sudo, leader of the Ar laboratory, and is optimized for the analysis of extremely small amounts of argon gas released by laser application.