摘要
胶东金矿集中区是中国最重要的黄金基地,三山岛金矿带位于该金矿集中区之胶西北成矿区的西部,近年来深部和海域隐伏区找矿取得重大突破。作为该区域重要的赋矿构造,三山岛断裂带进入海域后向两端延伸位置未能确定。为了查明三山岛断裂在南北两端进入海域后的延展位置,使用海底重力仪开展了海上大比例尺重力测量工作,对其位置进行了推断。在布伽重力异常图上,三山岛断裂表现为规模大、水平变化率大的重力梯级带,在平面上呈"S"形,向北由三山岛金矿延伸入海,向南从新立西延入渤海,跨海后经仓上、潘家屋子东延入渤海。为了确定三山岛断裂带向北东方向穿过三山岛北部海域超大型金矿床后的延展位置,根据重力异常推断的三山岛断裂北延位置,结合该金成矿带地质矿产特征,部署钻孔进行验证。钻孔内主要岩性有中细粒(含黑云母)二长花岗岩、钾化二长花岗岩、碎裂状二长花岗岩、绢英岩化花岗岩等,暗色脉岩有辉长岩及少量黑云母闪长岩、闪长玢岩等,其中暗色矿物黑云母等略具定向排列,脉岩均发生不同程度的蚀变。构造蚀变(矿化)带宽206.25m(876.59~1082.84m),与上盘围岩分界较为清楚,与下盘围岩呈渐变关系,圈定7层矿体,累计厚度28.3m,最厚的单层矿体视厚度16.06m。钻孔位置位于重力梯度变化宽缓的"鼻状区",且空间位置符合等距分布、对应产出、分段富集等分布规律,钻孔中见到多为黄铜矿化、方铅矿、黄铁矿等多金属硫化物矿化,为典型的第一矿集群特征,可以确定该地区继三山岛北部海域470吨超大型金矿发现之后,其北部区域又出现一个很有找矿前景的靶区。
The Sangshandao gold deposit belt is located in the western metallogenic area to northwest of the Jiaodong gold deposit cluster district, which is the most important gold base in China. Recent years has witnessed great breakthrough in ore prospecting in concealed areas such as deep earth and waters. As an important ore hosting structure, the positions of extension of the Sanshandao fault into the waters have not been determined. In order to find out the extended positions of the Sanshandao fault belt in the north and south ends into the waters, this study carried out marine large scale gravity measurement using INO sea floor gravimeter. In the Bouguer gravity anomaly map, the Sanshandao fault is characterized by a large scale gravity gradient belt with various gravity changes, which presents an “S” shape in the plane. The Sanshandao fault extends northward into the sea across the Sanshandao gold mine, and southward cross Xinli to the Bohai Sea and then passes through Cangshang and Panjiawuzi eastward to the Bohai Sea. Combined geological features of the gold metallgenic belt, the northeastern extension position of the Sanshandao fault was inferred using gravity anomaly data and confirmed through drilling deployment. The main lithology of the core is fine grained monzonitic granite （including biotite）, monzonitic granite, cataclastic granite, beresitization granite. Dark dykes are dominated by gabbro, with minor amount of biotite diorite and diorite porphyrite. The biotite minerals show directional arrangement and dykes underwent varying degrees of alteration. Tectonic alteration （mineralization） zone has a width of 20625 meter （87659m-108284m）. The alteration zone has obvious boundary with hanging wall rock and gradually changing alteration boundary with footwall rock. Seven layers of orebodies have been delineated, with an accumulated thickness of orebodies reaching to 283m and the largest apparent thickness of 1606 m for a single layer of orebody. Drilling positions are located within the nose shaped area of gravity gradient variation, and the spatial position is in accordance with the distribution law of the distance distribution, the corresponding output, distribution law of the segmented enrichment and so on. Drilling cores contain polymetallic sulfide mineralization, such as chalcopyrite, gelana, and pyrite, which shows the features of typical deposit cluster area. Therefore, it is concluded in this study that this area should be another target area with large prospecting potential after discovery of the 470 ton super large gold ore deposit in the offshore of the northern Sangsandao fault.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2017年第12期2771-2780,共10页
Acta Geologica Sinica
基金
国家重点研发计划专题项目(项目编码:2016YFC0600107-2)
中国地质调查局地质矿产调查专项项目(项目编码:12120113060400
12120114034901)资助的成果
关键词
三山岛断裂
金矿
海上重力测量
钻孔验证
海上找矿靶区
Sanshandao fault
gold deposits
Marine gravity measurement
drilling verification offshore prospecting target
