湖北大冶与矽卡岩型铁矿床有关的铁山岩体中黑云母、角闪石^40Ar-^39Ar同位素年龄及其地质意义  

^(40)Ar-^(39)Ar biotite and hornblende dating of Tieshan quartz diorite related to the skarn-type deposits in Daye area,Hubei Province,and its geological significance

作　　者：瞿泓滢[1,2,3] 裴荣富[2] 姚磊[4] 王永磊[2,3] 王浩琳[2,3] 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710064 [2]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 [3]南京大学内生金属矿床成矿机制研究国家重点实验室,江苏南京210093 [4]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《中国地质》2012年第6期1635-1646,共12页Geology in China

基　　金：科学技术部973课题(2012CB416802);国土资源部公益性行业课题(200911007-18);南京大学内生金属矿床成矿机制研究国家重点实验室基金项目(15-09-01)共同资助

摘　　要：长江中下游是中国东部中生代大规模成矿的重要地区之一,是中国东部一个重要的Cu-Fe-Au-Mo多金属成矿区带。鄂东南地区铜铁多金属矿床是长江中下游地区金属成矿带的重要组成部分,但关于岩体年龄及岩体热年代学的研究比较少,本文以湖北大冶与矽卡岩型铁矿床有关的铁山岩体中的黑云母与角闪石为研究对象,利用40Ar-39Ar阶段加热同位素定年方法对该岩体进行了成岩时代的研究,获得了黑云母、角闪石的40Ar-39Ar坪年龄分别为(133.0±1.0)Ma、(137.0±2.0)Ma,等时线年龄分别为(133.4±1.5)Ma、(137.3±1.6)Ma,结合前人的资料,认为黑云母、角闪石的40Ar-39Ar坪年龄代表了铁山岩体的成岩时代,结果与鄂东南地区和长江中下游地区成矿岩体年龄一致。与铜陵地区主要成矿岩体年龄对比,利用岩体冷速率与成矿关系以及小岩体成大矿的原理,铁山岩体冷速率偏高,成矿规模一般与冷速率呈反相关,但可能由于其有着特殊的生长结构,浅部小侵入体可以得到一定深度岩浆房的成矿流体和热能补充,以致会出现"小岩体成大矿"的现象。同时,在结合已有的岩石学、地球化学以及矿床同位素年龄资料基础上,可以推断出鄂东南地区早白垩世矽卡岩铁矿床形成于岩石圈伸展-减薄环境。The Middle-Lower Yangtze River belt is one of the large-scale Mesozoic metallogenic areas in eastern China and also an important Cu-Fe-Au-Mo metallogenic belt in eastern China.The polymetallic Cu-Fe deposits in southeast Hubei area constitute an important part of the Yangtze River belt;nevertheless,studies of rock body chronology and thermal chronology remain very insufficient.Biotite and hornblende of the Tieshan rock body related to the skarn-type Fe deposits in Daye of Hubei Province yield 40Ar-39Ar plateau ages of 133.0±1.0 Ma and 137.0±2.0 Ma and isochronal ages of 133.4±1.5 Ma and 137.3±1.6 Ma respectively.An integrated study of available petrological,geochemical and rock body U-Pb ages led the authors to believe that the rock body ages of southeast Hubei area are the same as the ages of the Yangtze River belt,and the skarn-type Fe mineralization in Daye of Hubei Province was associated with lithospheric extension and thinning during the Late Mesozoic in eastern China.Meanwhile,utilizing the rock body cooling rate theory（the mineralization scale retro-correlation to the rock body cooling rate）,the authors found that,although the cooling rate of the Tieshan rock body is rather higher in comparison with the cooling rates of the main mineralization rock bodies in Tongling,small shallow plutons could be complemented by ore-forming fluids and heat energy of deep magma chamber.

关 键 词：40Ar-39Ar同位素年龄 铁山岩体 冷速率 成岩成矿作用 湖北大冶 

分 类 号：P597.3[天文地球—地球化学]