地学时间单位Ma和Myr及其派生单位用法的探讨

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

摘要: 针对夏明生先生认为“Ma”及其派生单位(如“m/Ma”和“℃/Ma”)在地学期刊中属错误用法的观点,查阅了国家标准GB 3100-93和国际地学期刊有关规定。进而提出“Ma”和“Myr”均可表示“100万年”的观点,并指出这两个单位在国际期刊用法中的区别,即“Ma”用于表示某一地质事件距今的绝对年代(absolute dates),而“Myr”用于表示某一地质事件的延续时间或时间间隔(duration或interval)。另外,还提出了Ma”和“Myr”的派生单位供大家讨论。

Abstract: 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.