Calibration of the Lutetium-Hafnium Clock
Calibration of the Lutetium-Hafnium Clock
复制标题
DOI：
10.1126/science.1061372
复制
发表时间：
2001-07
期刊：
影响因子：
56.9
通讯作者：
E. Scherer;C. Münker;K. Mezger
中科院分区：
文献类型：
--
作者：
E. Scherer;C. Münker;K. Mezger
放射性衰减的定义明显的常数是地质学的基石，并且使用放射剂同位素来约束行星分化的时间尺度和机制。最近的衰减实验are based on the previously used λ176Lu of 1.93 × 10-11 to 1.94 × 10-11 year-1 are thus ∼4% too young, and the initial hafnium isotope compositions of some of Earth's oldest minerals and rocks become less radiogenic relative to bulk undifferentiated Earth when calculated using the new decay constant. The existence of strongly unradigenic hafnium in Early Archean and Hadean zircons implies that enriched crustal reserves在地球上存在43亿年前，并持续了2亿年或更长时间。
Well-defined constants of radioactive decay are the cornerstone of geochronology and the use of radiogenic isotopes to constrain the time scales and mechanisms of planetary differentiation. Four new determinations of the lutetium-176 decay constant (λ176Lu) made by calibration against the uranium-lead decay schemes yield a mean value of 1.865 ± 0.015 × 10−11 year−1, in agreement with the two most recent decay-counting experiments. Lutetium-hafnium ages that are based on the previously used λ176Lu of 1.93 × 10−11 to 1.94 × 10−11year−1 are thus ∼4% too young, and the initial hafnium isotope compositions of some of Earth's oldest minerals and rocks become less radiogenic relative to bulk undifferentiated Earth when calculated using the new decay constant. The existence of strongly unradiogenic hafnium in Early Archean and Hadean zircons implies that enriched crustal reservoirs existed on Earth by 4.3 billion years ago and persisted for 200 million years or more. Hence, current models of early terrestrial differentiation need revision.