| 德乌鲁岩体内外接触带金多金属成矿区成岩成矿地质地球化学特征及成因探讨 |
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| 引用本文： | 陈明辉,郭素雄,徐军伟,朱永新,余君鹏.德乌鲁岩体内外接触带金多金属成矿区成岩成矿地质地球化学特征及成因探讨[J].矿产与地质,2016(4):517-530. |
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| 作者姓名： | 陈明辉 郭素雄 徐军伟 朱永新 余君鹏 |
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| 作者单位： | 1. 湖南省有色地质勘查局二四五队，湖南 吉首 416007; 中南大学地球科学与信息物理学院，湖南 长沙 410083;2. 湖南省有色地质勘查局二四五队,湖南 吉首,416007;3. 中南大学地球科学与信息物理学院，湖南 长沙 410083; 湖南省有色地质勘查局二四七队，湖南 长沙 410129;4. 甘肃省地质调查院,甘肃 兰州,730000 |
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| 基金项目： | 中国地质调查局地质调查项目《中国矿产地质与成矿规律综合集成和服务(矿产地质志·甘肃卷)》(编号:DD20160346)资助 |
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| 摘 要： | 位于西秦岭西段夏河—合作金成矿带的德乌鲁岩体内外接触带金多金属成矿区,主要包括以地南、老豆、下看木仓、吉利及老虎山―阿什加等金矿床(点),其中以地南是德乌鲁岩体近年新探明的一处大型金矿。它们的成矿地质特征基本相似,矿床均产于岩体内外接触带,矿体呈脉(板)状、透镜状,严格受断裂破碎蚀变带控制。矿床的S-H-O-B稳定同位素组成特征表明,成矿物质和成矿流体主要来源于岩浆活动。LA-ICP-MS锆石U-Pb年龄显示,德乌鲁石英闪长岩和老豆石英闪长斑岩的锆石加权年龄分别为(238.6±1.3)Ma和(247.6±1.3)Ma;与金矿化紧密共生的绢云母40 Ar/39 Ar坪年龄为(248±3~249.9±2.7)Ma,成岩与成矿时代接近。岩石元素地球化学特征表明,这两类岩石地球化学性质相似,均为富碱、偏铝质、轻稀土元素富集、Eu中等到弱负异常、富集大离子亲石元素、亏损高场强元素,属于较典型的Ⅰ型花岗岩,具有活动大陆边缘弧岩浆地球化学属性。岩石的Sr-Nd同位素组成(87 Sr/86 Sr)=0.702~0.704,暗示其源区主要为富钾的基性下地壳,并有幔源物质加入。研究结果表明,成岩和成矿作用均发生于印支期,成矿作用可能与区域逆冲-推覆作用及相伴生的酸性岩浆侵位密切相关,矿床成因类型为岩浆热液成因。区域内构造发育,岩浆活动频繁,金多金属矿床(点)分布广泛,金资源潜力大,找矿前景良好。
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| 关 键 词： | 金多金属矿 成矿特征 地球化学 控矿因素 矿床成因 西秦岭 |
Diagenetic,metallogenic,geological and geochemical characteristics of gold polymetallic metallogenic province inside inner and outer contact zone of Dewulu rock mass |
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| CHEN Minghui;GUO SUxiong;XU JUNwei;ZHU Yongxing;YU Junpeng.Diagenetic,metallogenic,geological and geochemical characteristics of gold polymetallic metallogenic province inside inner and outer contact zone of Dewulu rock mass[J].Mineral Resources and Geology,2016(4):517-530. |
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| Authors: | CHEN Minghui;GUO SUxiong;XU JUNwei;ZHU Yongxing;YU Junpeng |
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| Institution: | CHEN Minghui;GUO SUxiong;XU JUNwei;ZHU Yongxing;YU Junpeng;No.245 Team of Hunan Nonferrous Metals Geology and Exploration Bureau;School of Geosciences and Info-Physics,Central South University;No.247 Team of Hunan Nonferrous Metals Geology and Exploration Bureau;Gansu Institute of Geological Servey; |
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| Abstract: | Gold polymetallic metallogenic province inside inner and outer contact zone of Dewulu rock mass is located at Xiahe-Hezuo gold metallogenic belt of Western Qinling.Gold deposits (ore occurrences)like Yidinan,Laodou,Xiakanmucang,Jili and Laohushan-Ashijia are distributed within the area.Among them,Yidinan deposit is a large-scale gold deposit which is newly discovered in Dewulu rock mass in recent years.These deposits have similar metallogenic and geological characteristics,and all occur inside the inner and outer contact zone of the rock mass.The orebodies mainly occur as veined (tabular)and lenticular in form and are strictly controlled by fractured and crushed alteration zone.The characteristics of S-H-O-B sta-ble isotope composition suggest that the metallogenic matters and metallogenic fluid mainly originate from magmatic activities.LA-ICP-MS zircon U-Pb dating reveals the following facts:the zircon dating weighted value of Dewulu quartz diorite and Laodou quartz diorite porphyry are (238.6±1.3)Ma and (247.6±1.3)Ma respectively;the 40 Ar/39 Ar plateau age of sericite which is closely associated with gold mineralization is (248 ±3-249.9 ±2.7)Ma,and the diagenetic epoch is close to metallogenic epoch.According to the element geochemical characteristics of rocks,it is known that the geochemical characteristics of these two kinds of rocks are similar to each other and the rocks are characterized by rich alkali,slightly rich aluminum,rich LREEs,medium-weak negative anomalies of Eu,rich LILEs (large ion lithophile elements),and depleted HFSEs (high field-strength elements).The rocks are typical type I granite which has geochemical properties of active continental marginal arc magma.The Sr-Nd isotope composition of the rocks is (87 Sr/86 Sr)=0.702-0.704,and it implies that its source area mainly is potassium-rich basic lower crust where mantle-derived materials enter.The research results suggested that diagenesis and mineralization took place in Indosinian period,and mineralization might be closely related to regional thrust-nappe and associated acidic magmatic emplacement,and the deposit is a magmatic hydrothermal deposit in terms of genesis.With well-developed structures,intense magmatic activities,widely distributed gold polymetallic deposits (ore occurrences),the area has great potential of gold resource and favorable prospecting prospect. |
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| Keywords: | gold polymetallic deposit metallogenic feature geochemistry ore-controlling factor deposit genesis Western Qinling |
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