Isochron technique

Bischoff JL, Fitzpatrick JA (1991) U-series dating of impure carbonates An isochron technique using total-sample dissolution. Geochim Cosmochim Acta 55 543-554 Broecker WS, Olson EA, Orr PC (1960) Radiocarbon measurements and annual rings in cave formations. Nature 185 93-94... 

The age of a mineral can be calculated via the isochrone technique using the equation ... 

The duration of chemical exchange between seawater and basalt can also be determined by isotopic studies of hydrothermal minerals. A variety of techniques have been used, ranging from direct dating by K/Ar and Rb/Sr isochron techniques to comparisons of the initial strontium isotopic composition of alteration minerals with the isotopic evolution of seawater (Gallahan and Duncan, 1994 Richardson et al., 1980). 

Also, Th released from the carbonate phase during acid dissolution may unpredictably adsorb to detrital particles if they are present. For these reasons, both Bischoff and Fitzpatrick (1991) and Luo and Ku (1991) independently concluded that isochron techniques that employ total sample dissolution give the most reliable results. 

The isochrons that we depict in this paper are simple two-dimensional isochrons. A rigorous treatment of isochron techniques requires the use of three-dimensional isochrons (e.g. Ludwig and Titterington, 1994). However, for our particular examples, variation in the ratio among sub-samples used to construct each isochron is negligible. 

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