Geochronological investigations in China were initiated nearly 50 years ago, mainly since the establishment of university programs teaching isotope geochemistry and the setup of geochronological laboratories. During the late 1970's and early 1990s, the geochronological framework of China's landmass has been established by numerous isotopic studies. (2008) The Bikou basalts in northwestern Yangtze Block, South China: remnants of 820-810 Ma continental flood basalts? Consequently, the basal Gondwana sequence in the southern part of the basin should lie at the Carboniferous–Permian boundary, not within the Sakmarian as previously considered.
Bimodality of granulometric composition is defined by input of material from various sources of different composition.
The amount of time required for half of a given quantity of a parent radioactive element to decay into the daughter product is referred to as the half-life.
It is important however, that the half-life of an element is defined in terms of probability and is not the time required for exactly 50% of a given quantity to decay (e.g.
there are not 1.5 atoms after 3 radioactive atoms experience one half-life).
The predictability of a half-life is greater when a greater number of atoms is observed and thus allowing for the quantification of half-lives.