胶东三山岛北部海域超大型金矿床的发现及其构造-岩浆背景  

Discovery and Tectonic-Magmatic Background of Superlarge Gold Deposit in Offshore of Northern Sanshandao,Shandong Peninsula,China

作　　者：宋明春 张军进 张丕建 杨立强[4] 刘殿浩 丁正江 宋英昕[4,5] 

机构地区：[1]山东省地质矿产勘查开发局,济南250013 [2]山东省地质勘查工程技术研究中心,济南250013 [3]山东省第三地质矿产勘查院,山东烟台264003 [4]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083 [5]山东省地质科学研究院,济南250013

出　　处：《地质学报》2015年第2期365-383,共19页Acta Geologica Sinica

基　　金：国家自然科学基金项目(编号:41230311);国家科技支撑计划课题(编号:2011BAB04B09);中国地质调查局地质调查项目(编号:12120114034901);山东省地质矿产勘查开发局科研和勘查项目资助的成果

摘　　要：胶东是我国最重要的黄金基地,近年来深部和海域隐伏区找矿又取得重大突破。尤其是,在莱州三山岛北部发现了海域超大规模金矿床。这一矿床与位于其南侧的三山岛矿区的深部主矿体相互连接,实际上为同一矿体,矿体全长超过3km,最大斜深超过1.7km,金资源总量超过500t,是我国规模最大的单一金矿体。矿床赋存于三山岛断裂下盘,为破碎带蚀变岩型金矿。其规模最大的4号矿体,赋存标高-796^-1736m,矿体走向长1446m,倾向最大延深1072m,平均厚度30.91m,平均品位5.23g/t。矿床由浅部矿体群和深部矿体群组成,二者均分布于控矿断裂倾角平缓和由陡变换的转折部位,构成由浅部至深部的台阶式分布特征,称之为阶梯式成矿模式。浅部第一台阶矿体赋存于-600m标高深度以上,矿体倾角25°~50°;深部第二台阶矿体赋存于-1000m标高以下,矿体倾角35°~40°。第一台阶与第二台阶的矿化特征有差异,后者矿体资源量多、规模大、厚度厚、品位高。控矿断裂——三山岛断裂的产状变化大,沿走向S形拐弯特征明显,沿倾向总体上显示浅部倾角陡深部倾角缓的铲式特点,且呈现倾角陡、缓交替变化规律,形成阶梯式断层。断裂下盘变形强,构造带厚度大;沿倾斜方向由浅部至深部,断裂带宽度变大、韧性变形特征增强、成矿空间增大,矿体厚度增大。这些特征指示,三山岛断裂具有铲式正断层性质。三山岛断裂的形成可能与郯庐断裂活动有关,郯庐断裂于早白垩世发生左行走滑时,在其东侧产生SEE向的伸展作用,形成了包括三山岛断裂在内的胶东地区的伸展构造。胶东侏罗—白垩纪岩浆活动强烈,玲珑型花岗岩、郭家岭型花岗岩、伟德山型花岗岩、崂山型花岗岩的地球化学特征研究表明,该区经历了由华北-扬子构造体系向欧亚-太平洋构造体系和由挤压机制向伸展机制的转换,由EM1型富集地幔�The Shandong Peninsula is one of the most important bases of gold resources in China.In recent years,a great breakthrough has been made for prospecting concealed gold deposits in deep and offshore areas.Especially,a superlarge gold deposit has been found in the offshore of northern Sanshandao.The main ore body in the offshore of northern Sanshanddao connect to the main ore body in the Sanshandao deep district,both of them is a unified ore body.It is the largest single gold ore body in China,with more than 500 tgold,3000mlength along its strike and1700 mlength along its tilt direction.The gold deposit in the off shore of northern Sanshandao occurs in the footwall of the Sanshandao fault,and is a typical gold deposit of fracture zone altered rock type.The largest No.4orebody is located at the level of-796^-1736 m,with a 1446 mlength along its strike,and 1072 malong its tilt direction.Its average thickness is 30.91 m,and average grade is 5.23g/t.This gold deposit consists of shallow and deep ore body groups,both of them are enriched at the gentle segments and the transitions from the steep to gentle along the deposit-controlled fault,forming a ladder-like or staircase distribution pattern,which termed as step metallogenetic model.The shallow ore bodies in the first step are above-600 m,with dip angle of 25°~50°.While the deep ore bodies in the second step are below-1000 m,with dip angle of 35°~40°,and have more gold resources,larger ore body scale,bigger thickness and higher grade than the shallow ones.The ore controlled fault,the Sanshandao Fault is a volatile S-shaped along its strike and a shovel-type along its inclined direction,coupled with an alternate variation dip angle between steepand slow,forming a ladder-type fault.Its footwall is deformed strongly and is of large thickness.From the shallow to the deep along inclination,the fault becomes larger in thickness,greater in ductile deformation,and increasing in the ore metallogenic space and ore body.All these characteristics suggest that the Sanshandao Fa

关 键 词：三山岛海域超大型金矿床 铲状阶梯式断层 热隆-伸展 构造-岩浆背景 胶东型金矿 

分 类 号：P618.51[天文地球—矿床学]