中国陆相二叠、三叠纪地层年代对比新进展

New progress on the correlation of Chinese terrestrial Permo-Triassic strata

总结了近10多年来陆相二叠、三叠纪地层年代的新认识,证据主要来自于同位素测年以及四足动物化石对比,集中介绍了新疆的准噶尔盆地和吐哈盆地、北祁连区和华北地层区的新对比方案。新疆吐哈盆地同位素测年的结果证实红雁池组及以下的芦草沟组属于乌拉尔统,泉子街组可能属于瓜德鲁普统,仅梧桐沟组及锅底坑组属于乐平统。红雁池组与泉子街组间存在很长沉积间断,而烧房沟组与克拉玛依组间也可能存在沉积间断。乌鲁木齐鲵时代与国外大多数西蒙螈类时代基本一致,是我国二叠纪最早的四足动物化石。由脊椎动物化石对比得知北祁连区的青头山组相当于瓜德鲁普统下部,而肃南组属于乐平统,中间可能存在沉积间断。华北上、下石盒子组都可能包括了很长时代的沉积,上石盒子组延续到吴家坪阶上部;根据锯齿龙类化石,孙家沟组基本属于二叠系;二马营组二段下部243.5 Ma的年龄支持这个组时代为安尼期晚期;铜川组顶部还为拉丁阶,没有延伸到卡尼阶。

This paper reviews recent works on the age of Chinese terrestrial Permo-Triassic strata, mainly based on the isotopic dating and the tetrapod correlation. For the application of U-Pb dating methods for the stage-level division of Permo-Triassic strata, the best method is the Thermal Ionization Mass Spectrometer（TIMS）, while the Secondary Ion Mass Spectroscopy（SIMS） can be used for many cases; however, the most popular Laser Ablation Inductively Coupled Plasma Mass Spectrometry（LA-ICPMS）, which has nearly 4% error（8 Myr）, is of little use（Li et al., 2015）.