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| 华北陆块北缘崇礼-赤城地区晚古生代花岗岩类的锆石年龄和Sr-Nd-Hf同位素组成 | |
| 引用本文： | 王芳,陈福坤,侯振辉,彭澎,翟明国.华北陆块北缘崇礼-赤城地区晚古生代花岗岩类的锆石年龄和Sr-Nd-Hf同位素组成[J].岩石学报,2009,25(11):3057-3074. |
| 作者姓名： | 王芳 陈福坤 侯振辉 彭澎 翟明国 |
| 作者单位： | 1. 中国科学院地质与地球物理研究所,固体矿产资源重点实验室,北京,100029;中国科学院研究生院,地球科学学院,北京,100039 2. 中国科学技术大学地球与空间科学学院,壳幔物质与环境重点实验室,合肥,230026 3. 中国科学院地质与地球物理研究所,固体矿产资源重点实验室,北京,100029 |
| 基金项目： | 科技部国家重点基础研究发展计划，国家自然科学基金委员会 |
| 摘 要： | 本文报道冀北崇礼-赤城地区晚古生代花岗岩类岩石的锆石U-Pb年龄和Sr-Nd-Hf同位素组成特征.它们出露在华北陆块北缘的构造单元内,侵位于中高级变质基底岩石红旗营子群中.锆石LA-ICP-MS定年结果表明,海流图花岗岩岩体记录了两期岩浆作用,即299±3Ma和254±11Ma;镇宁堡片麻状二长花岗岩和白花沟片麻状黑云母石英二长闪长岩分别形成于287±1Ma和252±3Ma.这些晚古生代花岗岩类岩石具有较低的初始~(87)Sr/~(86)Sr值(0.7062～0.7076)、低的ε_(Nd)(t)值(-18.1至-9.6)和古老的Nd亏损地幔模式年龄(2.49～1.87Ga).其锆石的ε~(Hf)(t)值变化在-13.2至-7.4之间,Hf平均地壳模式年龄值(T_(DM)~C)在2.15Ga至1.79Ga之间.锆石Hf同位素特征与全岩Nd同位素特征指示古老的华北陆块地壳物质是花岗岩浆的主要物源.在形成时代和地球化学特征上,崇礼-赤城地区晚古生代花岗岩与出露在东部丰宁-承德地区的花岗岩类岩石既有相似性,又有不同之处,可能代表华北陆块北缘不同构造背景下岩浆作用的产物. |
| 关 键 词： | 华北陆块 古生代 花岗岩 锆石年龄 Sr-Nd-Hf同位素组成 |
Zircon ages and Sr-Nd-Hf isotopic composition of late Paleozoic granitoids in the Chongli-Chicheng area, northern margin of the North China block |
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| WANG Fang,CHEN FuKun,HOU ZhenHui,PENG Peng,ZHAI MingGuo.Zircon ages and Sr-Nd-Hf isotopic composition of late Paleozoic granitoids in the Chongli-Chicheng area, northern margin of the North China block[J].Acta Petrologica Sinica,2009,25(11):3057-3074. | |
| Authors: | WANG Fang CHEN FuKun HOU ZhenHui PENG Peng ZHAI MingGuo |
| Abstract: | This study presents zircon U-Pb ages and Sr-Nd-Hf isotopic composition of late Paleozoic granitoids in the ChongliChieheng area of northern Hebei Province.These granitoids intrude in the medium-to high-grade metamorphic basement rocks of the Hongqiyingzi Group exposed in the tectonic unit within the northern into margin of the North China block.Zircon LA-ICP-MS dating results show that the Hailiutu granitic pluton records two stages of magmatism forming in 299±3Ma and 250±11Ma.The Zhenningpu gneissie granite and the Baihuaguo gneissie diorite are also dated at 287±1Ma and 253±3Ma,respectively.The late Paleozoic granitoid have low initial ~(87)Sr/~(86)Sr values of 0.7062 to 0.7076,low ε_(Nd)(t)values of-18.1 to-9.6,and old Nd depleted mantle model ages of 2.49Ga to 1.87Ga.ε_(Hf)(t)values and Hf average crust model ages(T_(DM) ~C)range from-13.2 to-7.4 and 2.15 Ga to 1.79Ga.A combination of zircon Hf and whole-rock Nd isotopic compositions indicates old crustal rocks of the North China block as major source material for the granitic magmas.From the evidence of the formation ages and geochemical composition,late Paleozoic granitoids in the Chongli-Chicheng area are similar to those exposed in the Fenning-Chengde area with some differences,both likely represent magmatic products forming in different tectonic regimes along the northern margin of the North China block. |
| Keywords: | North China block Paleozoic Granite Zircon age Sr-Nd-Hf isotopic composition |
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