geochronometer

Noun

geochronometer (plural geochronometers)

1. Any of several techniques used to measure the age of rock, especially any technique of radiometric dating, the measuring of the relative abundance of particular radioactive or radiogenic isotopes in order to evaluate the progress of radioactive decay.
   • Application of the K-Ca geochronometer therefore is best suited to minerals with high K/Ca ratios (Marshall & DePaolo, 1982) and K-bearing clay materials might appear to be amenable to its use.2009, P. J. Hamilton, “A review of radiometric dating techniques for clay mineral cements in sandstones”, in Richard Worden, Sadoon Morad, editors, Clay Mineral Cements in Sandstones, Wiley, page 273
   • Other geochronometers like ^{₈₇}Rb-\!^{₈₇}Sr, ^{₁₄₇}Sm-\!^{₁₄₃}Nd, or ^{₁₈₇}Re-\!^{₁₈₇}Os are also successfully applied to dating ore deposits and magmatic, metamorphic, or sedimentary processes.2019, Marek Smoluch, Giuseppe Grasso, Piotr Suder, Jerzy Silberring, editors, Mass Spectrometry, 2nd edition, Wiley, page 327
2. Any of several crystalline minerals that remain stable over geologic time and that when formed contained radioisotopes whose abundance relative to their decay products can be measured to calculate the age of the crystal (and thus that of the surrounding rock).
   • K-bearing minerals such as biotite, sanidine, plagioclase, and hornblende are geochronometers representative of the time of their crystallization once they were erupted from a volcano, and then transported into marine sedimentary basins.1997, G. S. Odin, A. Deino, M. Cosca, M. A. Laurenzi, A. Montanari, “F1: Miocene geochronology”, in A. Montanari, R. Coccioni, G. S. Odin, editors, Miocene Stratigraphy, Elsevier, page 584