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安徽潜山县双河大理岩锆石U-Pb年龄及其地质意义
Zircon U-Pb Ages of Marble from Shuanghe Qianshan County and Their Geological Significance
【摘要】 本文分析了安徽潜山双河大理岩的岩石化学成分、微量元素和稀土元素,并通过锆石"CL"图像,确定变质锆石和变质复合锆石测点位置。定年结果:①变质复合锆石中老核"继承锆石",共测定32个点,年龄范围在2357~342Ma:属于元古宙的15个,年龄范围在2357~572Ma,古生代17个,年龄范围在524~342Ma;②变质锆石共测定8个点,其中5个点年龄范围在249~234Ma,相当超高压变质时间,年龄范围在228~221Ma,即退变质时间。前述大量古生代的岩浆碎屑锆石(继承锆石)的存在,表明双河大理岩的原岩泥灰岩,时代不会早于古生代。
【Abstract】 Lithochemical compositions,trace elements and rare earth elements of the marble in Shuanghe were analyzed in this study.The positions of metamorphic zircons and metamorphic complex zircon were determined using CL zircon image.The dating results are listed as follows: 1) The older core "inherited zircon" in the metamorphic complex zircon were measured at 32 points with ages ranging from 2357 Ma to 342 Ma,15 of which belong to Proterozoic era with ages range from 2357 Ma to 572 Ma,17 to the Paleozoic from 524 Ma to 342 Ma.2) 8 points had been tested in the metamorphic zircons,and ages of 5 points fall with the scope of 249 Ma to 234 Ma corresponding to the UHP metamorphic time.The ages of 228~221 Ma represent retrograde time.Existence of a number of magmatic detrital zircons,i.e.inherite zircons,indicates that protolith of the Shuanghe marble rock is likely the argillaceous limestone with an age of later than the Paleozoic Era.
【Key words】 zircon U-Pb ages; marble; Shuanghe; Qianshan County; Anhui Province;
- 【文献出处】 地质学报 ,Acta Geologica Sinica , 编辑部邮箱 ,2012年04期
- 【分类号】P597.3
- 【被引频次】1
- 【下载频次】291