华北地块南缘熊耳山早中生代正长花岗岩--SHRIMP锆石U-Pb年龄、地球化学及意义  

The Early Mesozoic syenogranite in Xiong'er Mountain area,southern margin of North China Craton: SHRIMP zircon U-Pb dating,geochemistry and its significance

作　　者：李厚民[1] 王登红[1] 王晓霞[1] 张长青[1] 李立兴[1] 

机构地区：[1]中国地质科学院矿产资源研究所,国土资源部成矿作用与资源评价重点实验室,北京100037

出　　处：《岩石矿物学杂志》2012年第6期771-782,共12页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金资助项目(40572060);中国地质调查局国土资源大调查项目(1212010633903);国家科技支撑计划课题(2006BAB01A01);《中国地质志》资助项目(1212010811033)

摘　　要：报道了华北地块南缘河南熊耳山寨凹正长花岗岩的SHRIMP锆石U-Pb年龄为217.7±3.6 Ma,为早中生代。该正长花岗岩在岩石化学上高碱和Al,贫Mg、Fe;在微量元素上明显亏损Ba、Sr、P、Ti,相对富集高场强元素U、Th、Zr、Hf;在稀土元素上具有明显的四组分效应。研究结果表明,寨凹正长花岗岩与东秦岭北部富碱侵入岩、北秦岭褶皱带和南秦岭褶皱带早中生代花岗岩的地球化学特征有明显差异,为高分异的Ⅰ型花岗岩。其形成的构造环境与东秦岭地区其他早中生代侵入体相似,为后碰撞或后造山。This paper reports a syenogranite from Zhaiwa area in Xiong＇er Mountain on the southern margin of North China Craton. The syenogranite yielded a SHRIMP zircon U-Pb age of 217.7 ＋ 3.6 Ma and MSWD = 1.6, showing Mesozoic. The syenogranite is rich in alkaline and A1, but low in Mg and Fe. The trace elements are characterized by obvious depletion of Ba, Sr, P and Ti but relative enrichment of U, Th, Zr and Hr. The REE of Zhaiwa syenogranite has obvious tetrad effect. The geochemical features of the Zhaiwa syenogranite are different from those of the alkali-rich intrusive rocks in east Qinling and the early Mesozoic granitoids in north Qinling tectonic belt and south Qinling tectonic belt. The Zhaiwa syenogranite is a high-fractional I -type gran- ite. The tectonic setting for the Zhaiwa syenogranite is a post-collision or post-orogenic tectonic setting.

关 键 词：正长花岗岩 锆石U-Pb年龄 高分异Ⅰ型花岗岩 四组分效应 华北陆块南缘 

分 类 号：P588.12[天文地球—岩石学] P597.3[天文地球—地质学]