Isochron dating

Another example of Ra- Th isochron dating is provided by the study of Reagan et al. (1992) on phonolites erupted in 1984 and 1988 at Mt. Erebus (Antarctica). Glass-... 

Heath E, Turner SP, Macdonald R, Hawkesworth CJ, van Calsteren P (1998) Long magma residence times at an island arc volcano (Sonfriere, St. Vincent) in the Lesser Antilles Evidence from isochron dating. Earth Planet Sci Lett 160 49-63... 

Luo S, Ku T-L (1991) U-series isochron dating A generalized method employing total-sample dissolution. Geochim Cosmochim Acta 55 555-564... 

The Banco Senza Nome Nameless Bank) is a pinnacle rising to about 80 m below sea level from a high probably made of sedimentary rocks (Bec-caluva et al. 1981). K/Ar isochrone dating on dredged samples gave an age of 9.5 Ma (Beccaluva et al. 1981). 

Candy, I., Black, S. Sellwood, B.W. (2005) U-series isochron dating of immature and mature calcretes as a basis for constructing Quaternary landform chronologies for the Sorbas Basin, southeast Spain. Quaternary Research 64, 100-111. 

Whole-rock Rb-Sr isochron dates indicate that the Rennick Schist of the Daniels Range crystallized at about 532 20 Ma (Early Cambrian lUGS 2002) and that the sandy (psammitic) and clay-rich (pelitic) facies had elevated initial Sr/ Sr ratios of 0.7187 0.0009 and 0.7243 0.0009, respectively (Adams 1986). A Rb-Sr date of a single whole-rock sample reported by Faure and Gair (1970) was recalculated to 548 33 Ma based on initial ratios obtained by Adams (1986) and using the decay constant of Rb recommended by... 

The results in Table 12.6 indicate that sample 64.01 (Mt. Bumstead) yields a plateau date of 170.4 1.4 Ma which is statistically identical to 169.4 1.1 Ma derived from an Ar-isotope correlation diagram (Faure and Mensing 2005). These dates are more accurate and more precise than the conventional whole-rock K-Ar dates of 188.6 2.2 and 149.7 2.1 Ma of this sample. Two samples (64.10, Mt. Bumstead and 27.17, Storm Peak) did not form " ArT Ar plateaus, but the Ar-isotope ratios did define isochrons with dates of 167.5 3.8 and 161.8 8.6 Ma, respectively. Sample 27.46 (Storm Peak) produced a plateau-date of 129.0 5.0 and a 126 3.8 Ma isochron date both of which indicate major loss of " Ar consistent with the high abundance (85%) of devitrified matrix. 

As the precision attainable by this type of isochron dating improves with the incorporation of points with high ratios of radiogenic to common Pb, this approach is likely to be most successful on Precambrian crystals. 

Overlap of " Sm on " Nd means that Sm-Nd isochron dating is also best done after isolation of the Nd fraction, as for TIMS, although interferences can be corrected for reasonably successfully [128]. Speed of analysis is a great advantage compared with TIMS, but there is some doubt whether MC-ICP-MS analyses are as accurate as TIMS analyses [129]. This problem is likely to be compounded when spiked analyses are attempted. Fairly successful analyses of Nd isotope ratios by LA-MC-ICP-MS have been reported [130,131], but these have been geared towards... 

Fukuchi,T, and Imai, N. (1998). ESR isochron dating of the Nojima fault gouge, southwest Japan, using ICP-MS An approach to fluid flow events in the fault zone. Spec. Publ.— Geo/. Soc. London 261. 

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