(U‐Th)/He chronometry experiences a renaissance

Abstract

Radioactive decay of naturally occurring nuclides provides the basis for nearly all of the quantitative temporal constraints on geophysical phenomena, from climate dynamics on scales of 10 2 –10 3 years, to planetary differentiation over 10 8 –10 9 years. In general, there are few geologic problems that cannot be resolved by radioisotopic chronometers, partly because of the wide range of radioactive parent nuclides and decay rates, contrasting chemical behaviors of parent and daughter atoms during common geologic processes, and ever‐advancing geoanalytical techniques. Despite broad success, however, radioisotopic techniques are still difficult to apply to many important geologic phenomena requiring temporal constraints, such as the timing and rates of shallow crustal processes that are critical aspects of geomorphology and neotectonics.