宁芜盆地玢岩型铁矿床的成矿时代:金云母^(40)Ar-^(39)Ar同位素年代学研究  

Geochronology of the Porphyry-like Type Iron Deposits in Ning-Wu Basin: Evidence from ^(40)Ar-^(39)Ar Phlogopite Dating

作　　者：范裕[1] 周涛发[1] 袁峰[1] 张乐骏[1] 钱兵[1] 马良[1] 谢杰[1] 杨西飞 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]安徽省化工地质勘查总院,安徽马鞍山243031

出　　处：《地质学报》2011年第5期810-820,共11页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号40830426;40803015);国家"深部探测技术与实验研究专项计划"专题(编号SinoProbe-03-02-05);国土资源部公益性行业科研专项项目课题(编号201011047-07);中国地质调查局地质调查工作项目(编号:1212011121115);安徽省地质公益性地质项目(编号2007-1);新世纪优秀人才支持计划项目(NCET-10-0324)资助的成果

摘　　要：宁芜盆地是长江中下游成矿带的重要组成部分,盆地内广泛产出玢岩型铁矿床,但其精确的成矿时代及其形成构造背景研究仍十分薄弱。本文在详细野外地质工作的基础上,选择与磁铁矿密切共生的金云母为对象,利用40Ar-39Ar阶段加热同位素定年方法,对盆地内典型玢岩型铁矿床进行了成矿时代研究,确定了盆地内主要玢岩型铁矿床陶村、白象山和和睦山矿床的成矿时代分别为129.3±1.1Ma、130.7±1.1Ma和129.1±0.9Ma。结合矿床地质特征和闪长玢岩成岩时代,确定宁芜盆地内玢岩型铁矿床的成矿时代均为130Ma左右,其形成时代明显晚于长江中下游成矿带断隆区内的斑岩型-矽卡岩型铜(铁)、金矿床。宁芜盆地内玢岩型铁矿床形成于区域岩石圈伸展的构造环境。The Ning-Wu Basin is the important component of the Middle-Lower Yangtze metallogenic belt,which hosts many a porphyry-like type iron deposits.However,the research for precise ore-forming epoch and tectonic setting has been very poor.Basing on detailed field geological works,we present new 40Ar-39Ar phlogopite ages for the typical Taocun,Baixiangshan and Hemushan iron deposits to constrain the timing and duration of mineralization in the basin.Phlogopite from the Taocun,Baixiangshan and Hemushan iron deposits yielded 40Ar-39Ar plateau ages of 129.3±1.1Ma,130.7±1.1Ma and 129.1±0.9Ma,respectively.The dating results indicate that different porphyry-like type iron deposits in the Ning-Wu Basin all formed in early stage of Early Cretaceous about 130 Ma,obviously later than skarn-porphyry Cu-Au deposits related to high-k calc-alkaline intrusions in uplift areas.The porphyry-like type iron deposits in the Ning-Wu volcanic basin is believed to form under a regional lithospheric and thinning environment.

关 键 词：成矿时代 玢岩型铁矿 宁芜盆地 构造背景 

分 类 号：P597.3[天文地球—地球化学] P618.31[天文地球—地质学]