中国中—新元古代地层年表的修正——锆石U-Pb年龄对年代地层的制约

NEW GEOLOGIC TIME SCALE OF MESO-AND NEOPROTEROZOIC OF CHINA AND GEOCHRONOLOGIC CONSTRAINT BY SHRIMP ZIRCON U-Pb DATING

报道了全国地层委员会的中一新元古代地层年表新标定的方案：即长城系限定在L8～1，6Ga；蓟县系限定在1．6～1．4Ga；待建系1.4～1．0Ga；青白口系限定在1．0～0．78Ga；南华系限定在780～635Ma及震旦系限定在635～542Ma。新年表突出3个方面的标定：1）对长城系和蓟县系的年代学限定；2）依据蓟县剖面的新年龄信息，在中国年表中表示了“待建系”的位置；3）对南华系下限的限定。依据新地层年表，有关的地层对比和构造背景解疑将发生重大变化。中国华北古陆、扬子古陆和塔里木块体上最新的系列锆石U—Pb测年结果，初步揭示中国古陆前寒武系火山事件的存在和分布范围，结合全球的大陆动力学的基本特征，将有利于建立一个前寒武纪统一的、精确的和具有年代系统的高精度年龄的地层年表。

On the basis of the new remarked the Preeambrian stratigraphical column of China, which is discussed by the National Commission on Stratigraphy of China on Aug. , 2010. The Changcheng System is limited in 1.8-1.6 Ga. The Jixian System is limited in 1.6-1.4 Ga. Unnamed system （1.4-1.0 Ga） only developed the Xiamaling Formation in the Jixian section. The Qingbaikou System is limited in 1.0 0.78 Ga. The Nanhua System is in 780-635 Ma and The Sinian System is in between 635 - 542 Ma. There three important markers in the new geologic time scale. 1） The Changcheng System and the Jixian System are reformed in it; 2） According to the SHRIMP zircon U-Pb dating, the unnamed system is left in the time scale; and 3） the lower boundary age of the Nanhua System is limited at 780 Ma. Because the big problems is the strata division and correlation in restudy of new regional geology in each provinces by Chi- nese Geological Survey and according to the new geologic time scale of Meso and Neoproterozoic of China, it is big changes in Precambrian strata correlation and tectonic explanation. According to new zircon U-Pb dating found in North China Plate, Yangtze Plate and Talimu Plate, it primary shows the volcanic province and distribution. Dealing with the basic global geodynimics, it is useful to set up a basic late Precambrian section of unify, practical and high precision chronological dating.