LI Chengjun, LUO Zhenfu, DENG Qun, JIN Xiaoyan, WANG Jihong. On time units Ma and Myr as well as their derived units in geological journals[J]. COAL GEOLOGY & EXPLORATION, 2010, 38(2): 79-80. DOI: 10.3969/j.issn.1001-1986.2010.02.020
Citation: LI Chengjun, LUO Zhenfu, DENG Qun, JIN Xiaoyan, WANG Jihong. On time units Ma and Myr as well as their derived units in geological journals[J]. COAL GEOLOGY & EXPLORATION, 2010, 38(2): 79-80. DOI: 10.3969/j.issn.1001-1986.2010.02.020

On time units Ma and Myr as well as their derived units in geological journals

  • Aiming at the point of view,held by Mr.Xia Mingsheng,that in geological journals,the time unit "Ma" and its derived units such as "m/Ma" and "℃/Ma" are illegal,we referred the stipulations about this issue by the national standard GB 3100-93 and by some foreign geological journals.Based on these stipulations,we propose that both "Ma" and "Myr" can be used to express a time length of millions of years.However,there is a certain difference between them,"Ma,Mega-annum" means millions of years ago(absolute dates) while "Myr,Millions of years" means the duration of time that a geological event lasted.Therefore,the derived units of "settlement rate or accumulation rate" and "cooling rate" can be expressed by "m/Ma" and "℃/Ma" for journals of Chinese edition and "m/Myr" and "℃/Myr" for English edition,respectively.
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