武当地块基性岩墙群及耀岭河群基性火山岩的Sr、Nd、Pb、O同位素研究  

Study on the Sr, Nd, Pb and O isotopes of basic dyke swarms in the Wudang block and basic volcanics of the Yaolinghe Group

作　　者：张成立[1] 周鼎武[1] 金海龙[2] 韩松[3] 刘颍宇 

机构地区：[1]西北大学地质系,西安710069 [2]新疆师范大学地理系,乌鲁木齐830054 [3]中国科学院高能物理研究所,北京100081

出　　处：《岩石学报》1999年第3期430-437,共8页Acta Petrologica Sinica

基　　金：国家自然科学基金

摘　　要：武当地块基性岩墙群与耀岭河群基性火山岩的 Ｓｒ、 Ｎｄ、 Ｐｂ 同位素特征反映它们具相同的混合地幔源区。前者的（８７ Ｓｒ／８６ Ｓｒ）ｉ＝ ０６９０５～０７０６１， ε Ｎ ｄ （ｔ） ＝ － １９～５０， Δ２０８ Ｐｂ／２０４ Ｐｂ＝ ３５４９～１９０２６， Δ２０７ Ｐｂ／２０４ Ｐｂ＝ ４～８５， Ｔｈ／ Ｔａ 低， Ｌａ／ Ｙｂ 变化大；后者的（８７ Ｓｒ／８６ Ｓｒ）ｉ＝ ０６４８７～０７０７５，ε Ｎ ｄ（ｔ）＝ ０１１～３９４， Δ２０８ Ｐｂ／２０４ Ｐｂ＝ － ８１５８～２１９９５， Δ２０７ Ｐｂ／２０４ Ｐｂ＝ ４４４～１６６８， Ｔｈ／ Ｔａ 和 Ｌａ／ Ｙｂ 较高。这指示它们的源区以岩石圈亏损地幔和第２ 类富集地幔为主要混合组分， 耀岭河群基性火山岩曾遭受地壳物质的混染。结合它们具大陆拉斑玄武岩地球化学特征， 代表同源异相裂谷环境的产物推断， 南秦岭基底陆块在新元古代时曾发生过一次重要裂解作用， 并向早古生代秦岭洋盆转变。The Sr, Nd and Pb of Wudang basic dyke swarms and basic volcanics of Yaolinghe group display that they were derived from the same mixing source of multi component The Wudang basic dyke swarms have ( 87 Sr/ 86 Sr) i=0 6905～0 7061, ε Nd ( t )=-1 9～5 0, Δ 208 Pb/ 204 Pb=35 49～190 26, Δ 207 Pb/ 204 Pb=4～85, low Th/Ta and wide range of La/Yb; and the basic volcanics of Yaolinghe group have ( 87 Sr/ 86 Sr) i of 0 6487～0 7075,ε Nd ( t )=0 11～3 94, Δ 208 Pb/ 204 Pb=-81 58～219 95, Δ 207 Pb/ 204 Pb=4 44～16 68 and higher Th/Ta and La/Yb, indicating that their source was mainly combined by DM and EMII and the basic volcanics of Yaolinghe group was contaminated with crust materials en rout to the surface Based on their geochemical feature with continental tholeiitic basalts and being products of different facies drived from the same source, it can be concluded that an important rifting in the south Qinling basement block occurred during Neo Proterozoic, and then entered into a setting of ocean basin in the early Paleozoic

关 键 词：基性岩墙群 基性火山岩 同位素 锶 钕 火山岩 

分 类 号：P588.14[天文地球—岩石学] P597[天文地球—地质学]