晋冀蒙交界地区五期岩墙群的界定及其构造意义

Identification of 5 Time—Groups of Dike Swarms in Shanxi—Hebei—Inner Mongulia Border Area and Its Tectonic Implications

以幔源岩浆侵位为标志的岩墙群是伸展作用的产物。根据同位素年龄测定 ,华北克拉通北缘晋冀蒙交界地区基性岩墙群可分为 :180 0～ 170 0 Ma,80 0～ 70 0 Ma,2 30 Ma,14 0～ 12 0 Ma,5 0～ 4 0 Ma五个年龄组。本文通过这五组岩墙群的地质、岩石及同位素地球化学特征的研究 ,探讨本地区地幔物质组分随时间的演变规律 ;并将本地区出现的五期伸展作用与华北克拉通乃至全球同期的重要构造事件进行对照。

Dike swarms marked with intrusion of mantle source magma result from extension. The basic dike swarms around Shanxi—Hebei—Inner Mogolia borders in the north peripheral area of North China Craton can be divided into five age-groups according to isotopic age determination: 1800～1700 Ma, 800～700 Ma, 230 Ma, 140～120 Ma, and 50～40 Ma. Geological, petrological and isotope-geochemical features of the five groups are investigated in order to explore variation of the mantle material composition in the concerned area with time. And the various extensional activities reflected by the five groups of dike swarms are compared with some important tectonic events within North China Craton as well as around the world during tha same period.