中国大陆地壳单颗粒锆石U-Pb年代学特征:国内文献数据的初步分析

Preliminary analysis of the Chinese sub-database of the Chinese crust single-grain zircon U-Pb geochronology database

锆石U-Pb年代学方法已经成为地质学研究必不可少的方法。本文收集整理了二十世纪八十年代以来分散在期刊论文、学位论文等多种出版载体中的锆石U-Pb年代学数据,建成中国大陆单颗粒锆石数据库中文子库。该数据子库涉及截至到2017年底的文献2331篇,有效数据154768条目,数据总量已经能够用来进行数据的初步分析和相关地球科学研究。数据子库中年龄-年龄绝对误差关系的分析表明,Age(^(206)Pb/^(238)U)、Age(^(207)Pb/^(235)U)、Age(^(207)Pb/^(206)Pb)在不同的地质年代区间误差表现有所不同。在小于1684.4Ma、1684.4~2855.2Ma、大于2855.2Ma年龄区Age(^(206)Pb/^(238)U)、Age(^(207)Pb/^(235)U)、Age(^(207)Pb/^(206)Pb)的误差最小、置信度最好,除了Age(^(207)Pb/^(235)U)测试方法的原因外,Age(^(206)Pb/^(238)U)和Age(^(207)Pb/^(206)Pb)可分别作为不同年龄段的推荐年龄。将选用的推荐年龄运用于LA-ICP-MS、SHRIMP、SIMS三种方法的比较,得出其适用于不同地质年代的范围。推荐年龄运用于年龄-频数图中并使用高斯多峰拟合,则可发现中国大陆锆石存在6个生长峰期,分别为131.71Ma、255.17Ma、442.42Ma、811.56Ma、1868.36Ma和2505.31Ma等;更小尺度下的新生代则存在七个峰期,分别为16.99Ma、27.64Ma、35.26Ma、43.44Ma、48.27Ma、52.74Ma和62.07Ma等,峰期及其对应测试点的位置可与中国大陆地壳演化重大历史事件对应。

The zircon U-Pb geochronology method has become an indispensable method for geologic research.This paper collected the zircon U-Pb geochronology data scattered in various publications such as journal articles and Master or Doctoral Dissertations in China since 1980s,and built a sub-database of the Chinese single-grain zircon age database.The sub-database covers 2331 documents published by the end of 2017,with valid data reaching 154,768 entries,which can be used for preliminary analysis of the big data and related earth science research.The analysis of the age-age absolute error relationships in the sub-database shows that the errors of Age（^（206）Pb/^（238）U）,Age（^（207）Pb/^（235）U）,and Age（^（207）Pb/^（206）Pb）are different in different geological time intervals.Because of their smallest errors and best confidences,Age（^（206）Pb/^（238）U）,Age（^（207）Pb/^（235）U）,and Age（^（207）Pb/^（206）Pb）can be selected as the recommended ages for different geological time intervals.Age（^（206）Pb/^（238）U）,Age（^（207）Pb/^（235）U）,and Age（^（207）Pb/^（206）Pb）can be selected as the recommended age in the age range of less than 1684.4Ma,1684.4~2855.2Ma,and greater than 2855.2Ma,respectively,although Age（^（207）Pb/^（235）U）is complicated.The recommended age chosen was applied to the comparison of LA-ICP-MS,SHRIMP and SIMS,and it was found that the three different methods are applicable to different geological ages.The recommended age is applied to draw the age-frequency diagram,then Gaussian multi-peak fitting is used to find that there are six growth peaks in zircons in China of131.71Ma,255.17Ma,442.42Ma,811.56Ma,1868.36Ma and 2505.31Ma,and seven peaks in the Cenozoic in smaller scales,i.e.,16.99Ma,27.64Ma,35.26Ma,43.44Ma,48.27Ma,52.74Ma and 62.07Ma.The location distribution of test points which represent every peak and every peak itself can correspond to geological events in the China's Mainland.