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

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。

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.