武当群变质岩年龄

出露于湖北省西北部武当群的形成年龄长期争论。本文报道了采自湖北省十堰市北、武当山太子坡和房县土城的武当群变质火山岩样品的Sm-Nd、Rb-Sr年龄测定结果。原划武当群可能由两部分变质火山岩组成。一部分变质火山原岩形成于1927Ma左右，火山岩物质来自类似MORB地幔源区，岩石形成过程中未见明显地壳物质污染，是真正武当群；另一部分变质火山岩形成于1175－871Ma间，和耀岭河群、郧西群变质火山岩原岩形成年龄类似，岩石同位素组成也有亲缘性。在复杂地质作用地层时代研究中，如果从少量Nd同位素研究入手可能会收到好的效果。

The age of metamorphic rocks of the Wudang Group

Abstract: There have long been disputes about the age of the Wudang Group exposed in northwestern Hubei. This paper Reports the results of Sm? Juan Nd and Rb? Juan Sr dating of samples of metavolcanic Rocks of the the Wudang Group from North of Shiyan City, Taizipo of Wudang Mountain and Tucheng of in Fangxian County. The former Wudang Group consists of rocks of two parts of metavolcanic different ages. The protolith of one part of metavolcanic rocks originated at ~ 1972Ma and the materials of the volcanic rocks were derived from an area similar to the MORB mantle source area, During rock formatim no significant contamination with crustal material occarred; so they are the real Wudang Group . The age of the protolith of the other part is 1175-871Ma, similar to that of the protoliths of metavolcanic rocks of the Yaolinghe and Yunxi Groups, and their istopic compositions also show that this part of rock has an affinity to the latter. In the study of the stratigraphic age in an area with complex geological processes, good results may be obtained if we start with microscopic Nd isotope study.