{"thcode":2,"term":{"code":1007,"name":"rubidium-strontium analysis","parent":954,"scope":"Technique for dating ancient rocks based on measuring the ratio of the isotopes strontium-87 to ribidium-87 in samples. Uses the known half-life of radioactive isotopes of rubidium-87 that decay to isotopes of strontium-87 to determine rock ages."},"uf":[{"name":"Rb-Sr age analysis","usewith":false}],"bt":[{"code":954,"name":"radiometric dating","parent":609,"scope":"Methods for age determination of rocks and fossils by measuring the proportions of naturally occurring radioactive isotopes to their decay products."},{"code":609,"name":"isotopic analysis","parent":619,"scope":"Experimental determination of the proportion of a given isotope (or isotopes) in a sample."},{"code":619,"name":"laboratory methods","parent":734,"scope":"Techniques to analyze and test samples in a place equipped and designed for the work."},{"code":734,"name":"methods","parent":1,"scope":"Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[],"rt":[{"code":438,"name":"geochronology","parent":464,"scope":"Study of the age of the earth by dating geological formations, rocks, and fossils."}]}