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| 松潘-甘孜地体内花岗岩锆石SHRIMP U-Pb定年及其构造意义 | |
| 引用本文： | 胡健民,孟庆任,石玉若,渠洪杰.松潘-甘孜地体内花岗岩锆石SHRIMP U-Pb定年及其构造意义[J].岩石学报,2005,21(3):867-880. |
| 作者姓名： | 胡健民 孟庆任 石玉若 渠洪杰 |
| 作者单位： | 1. 中国地质科学院地质力学研究所,北京,100081 2. 中国科学院地质与地球物理研究所,北京,100029 3. 北京离子探针中心,北京,100037 |
| 基金项目： | 国家自然科学基金项目(40272097) 中国科学院知识创新项目(KZCX2-XW-119) 中国地质调查局项目1212010510109资助成果 |
| 摘 要： | 松潘-甘孜地体总体上是一个三角状褶皱带,其北侧、东南侧及东侧分别与东昆仑-西秦岭构造带、金沙江构造带及龙门山构造带相邻。地体内几乎全部被三叠系浊积岩所覆盖,其中侵位了很多花岗岩体。显然,这些花岗岩的岩浆特征、来源与侵位时代,对研究松潘-甘孜地体基底性质、构造演化等问题具有重要意义。本文报道利用SHRIMP定年技术对一些花岗岩岩体锆石所进行的精确测年数据。测试结果表明:(1)松潘-甘孜地体内的花岗岩体主要形成于晚三叠世,但岩浆活动可延续到早侏罗世晚期;(2)早期花岗岩浆活动与三叠纪系褶皱变形大致同期,指示这一时期的花岗岩浆的形成可能与三叠系下部大型拆离滑脱构造相关;(3)花岗岩结晶锆石普遍具有浑圆状或不规则状较老的继承锆石核,这些核部继承锆石可能代表花岗岩浆在上升过程中从不同地层内捕获的碎屑锆石,或者是下地壳岩石深熔残留锆石。根据SHRING U-Pb定年,这些继承锆石的年龄分别为二叠纪、加里东期、晚元古代和早元古代。元古代碎屑锆石的存在也可能指示松潘-甘孜地体具前寒武系基底。 |
| 关 键 词： | 松潘-甘孜地体 花岗岩 锆石 SHRIMP测年 |
| 文章编号： | 1000-0569/2005/021(03)-0867-80 |
| 修稿时间： | 2004年12月6日 |
SHRIMP U-Pb dating of zircons from granitoid bodies in the Songpan-Ganzi terrane and its implications |
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| HU JianMin,MENG QingRen,SHI YuRuo and QU HongJie Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing,China Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing,China Beijing SHRIMP Center,Beijing.SHRIMP U-Pb dating of zircons from granitoid bodies in the Songpan-Ganzi terrane and its implications[J].Acta Petrologica Sinica,2005,21(3):867-880. | |
| Authors: | HU JianMin MENG QingRen SHI YuRuo and QU HongJie Institute of Geomechanics Chinese Academy of Geological Sciences Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Beijing SHRIMP Center Beijing |
| Abstract: | The Songpan-Ganzi terrane is in general a triangular fold belt, bounded on the north, southeast and east by the eastern Kunlun-western Qinling tectonic belt, the Jinsha river tectonic belt and the Longmenshan tectonic belt, respectively. It is mainly composed of Triassic turbidite, which is intruded by many granitoid bodies. It is obvious that the composition, sources and time of the granitic magma are very important for studing the basement and tectonic evolution of the Songpan-Ganzi terrane. This paper reports some SHRIMP U-Pb dating results for zircons from granitoids in the Songpan-Ganzi terrane. The dating results are as follows: (1) The granitoid intrusions occurred in the Late Triassic and Early Jurassic; (2) The earl-stage magmatism was nearly simultaneous with the folding of Triassic strata, suggesting that the magmatism might have related with a large detachment under the Triassic strata; (3) Some of the crystal zircons contain rounded or unregular cores in shape, and it is thought that the rounded zircons were captured from the wall rocks during the upwelling of the granitic magma or detrital zircons from partial melting of the lower crust. Based on the SHRIMP dating, the core zircons yield ages of the Permian, early Paleozoic, late Paleozoic, and early Proterozoic, respectively. The present of Proterozoic detrital zircons indicate that the Songpan-Ganzi terrane is presumably floored with Precambrian basement rocks. |
| Keywords: | Songpan-Ganzi terrane Granitoid Zircon SHRIMP U-Pb dating |
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