皖南及邻区燕山期两个类型花岗岩地球化学对比与岩石成因  

Petrogenesis and Geochemical Comparison of Two Types of Yanshanian Granite in South Anhui and its Surrounding Area

作　　者：翁望飞[1] 支利庚[1] 蔡连友[1] 徐生发[1] 王邦民[1] 

机构地区：[1]安徽省地质矿产勘查局332队地调院,安徽黄山245000

出　　处：《矿物岩石地球化学通报》2011年第4期433-448,共16页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：安徽省国土资源厅公益性地质调查基金资助项目(2010-g-11)

摘　　要：皖南周边分布着40余处大小不等的燕山期花岗岩体,依据岩石年龄可划分出2个幕次:一是130～170Ma,平均145Ma,为晚侏罗世-早白垩世早期(J3-K11),以花岗闪长(斑)岩为主;二是109～132.2Ma,平均123.5Ma,为早白垩世中、晚期(K12),岩性为花岗岩。研究表明,J3-K11花岗闪长岩为C型、高钾钙碱性埃达克岩,发育于造山后构造,应力由挤压转变为伸展的转折期,源自印支期加厚地壳部分熔融。而K21幕花岗岩为A2型花岗岩,产生于造山后的构造伸展环境,源自正常安山质地壳在印支期加厚地壳熔融结束之后继续受地幔物质底侵部分熔融。埃达克岩与斑岩铜矿及金、银等矿床成因上密切相关,A型花岗岩富集稀土元素及W、Zr、Nb、Ta、U等。因此加强皖南及邻区埃达克岩和A型花岗岩的研究,可为该地区寻找斑岩铜矿床及稀土、稀有金属等矿床提供一个新的思路和方向。More than 40 Yanshanian granites are distributed in south Anhui and surrounding area,and ages of these granites can be classified into two stages：the first stage belongs to J3-K11,130～170 Ma with an average age of 145 Ma,and the second stage belongs to K21,109～132.2Ma with an average age of 123.5 Ma.The analysis of petrological and geochemical characteristics shows that the granodiorites of J3-K11 in south Anhui and vicinities are C type,high-K calc-alkaline adakite（HKCAA）,formed from partial melting of the thickened lower crust by delamination in Mesozoic in eastern China.The analysis of geochemical characteristics of the granites in K21 shows that they are A2-type granites,formed in extensional environment after orogeny,resulting from partial melting of andesitic crust after the formation of adakite.In addition,a close relationship exists among adakite,porphyry copper and multi-metal deposits,and A-type granite plays a important role in the enrichment of rare earth elements,such as,W,Zr,Nb,Ta,U and so on.Therefore,thorough researches on adakite and A-type granite in south Anhui and vicinities will provide new ideas and directions for the exploration of porphyry copper,rare earth element and rare metal deposits.

关 键 词：地球化学特征 埃达克岩 A型花岗岩 岩石成因 构造环境 燕山期 皖南 

分 类 号：P588.121[天文地球—岩石学]