歙县细碧-角斑岩地球化学特征及其地质意义  

Geochemical characteristics of spilite-ceratophyre in Shexian and its geological significance

作　　者：余良范[1] 马良[1] 朱强[2] 胡召齐[2] 

机构地区：[1]安徽省公益性地质调查管理中心,安徽合肥230001 [2]安徽省地质调查院,安徽合肥230001

出　　处：《合肥工业大学学报（自然科学版）》2017年第4期539-546,共8页Journal of Hefei University of Technology：Natural Science

基　　金：安徽省公益性地质工作资助项目(2012-g-38)

摘　　要：安徽歙县西村岩组细碧-角斑岩为蛇绿岩套的重要组成部分,文章对细碧-角斑岩开展了激光剥蚀电感耦合等离子体质谱(laser ablation-inductively coupled plasma mass spectrometry,LA-ICP MS)锆石U-Pb年龄测定和全岩主、微量及稀土元素、锶钕同位素地球化学的分析工作,得到细碧岩和角斑岩的结晶年龄分别为(853±20)Ma和(852.9±8.2)Ma,此结果表明其形成在850 Ma左右的新元古代。岩石地球化学分析显示细碧岩和角斑岩具有岛弧玄武岩的特征,岩浆来源于亏损型地幔,并受到地壳流体的交代,岩石形成于俯冲背景下的弧后盆地环境,综合分析显示伏川蛇绿岩为形成于弧后盆地环境的"SSZ"型蛇绿岩。The spilite-ceratophyre in the Xicunyan group is an important part of the ophiolite suit in Fuchuan district, Shexian, Anhui Province. In this paper, the zircon laser ablation-inductively coupled plasma mass spectrometry（LAqCP MS） U-Pb isotopic dating, whole-rock major and trace elements and Sr-Nd isotopic geochemistry of spilite-ceratophyre were analyzed after geological work. The zircon LA-ICP MS U-Pb isotopic ages of the spilite and ceratophyre are （853i20） Ma and （852.9~8. 2） Ma respectively, suggesting that they are formed in Neoproterozoic. The whole-rock geochemistry analy- sis shows that the spilite-eeratophyre are island arc basalt, the magma was derived from the depleted mantle and affected by crustal fluid metasomatism. These spilite-ceratophyre rocks were formed in the back-arc basin under subduction environment. This study further proofs that Fuchuan ophiolite is the SSZ type ophiolite.

关 键 词：细碧-角斑岩 锆石LA-ICPMSU_Pb年龄 弧后盆地 SSZ型蛇绿岩 安徽歙县 

分 类 号：P581[天文地球—岩石学]