旬北地区志留系铅锌矿成矿规律及找矿方向

【作者】 赵国斌；

【导师】 隗合明；

【作者基本信息】 长安大学 ， 矿物学、岩石学、矿床学， 2005， 硕士

【摘要】 本文在较深入系统研究总结了旬北地区志留系铅锌矿床地质特征与地球化学特征的基础上,重点研究了其成矿规律,并提出了今后该地区的找矿方向。 根据铅锌矿产出的具体层位以及空间分布等特点,从北向南,研究区内志留系铅锌矿床可划分为三个矿带,北带为泗人沟—南沙沟铅锌成矿带,中带为红土坡—韩氏沟—小沟铅锌成矿带,南带为西营—黄石板铅锌铜成矿带。 旬北地区志留系铅锌矿床产于细碎屑岩中,矿体呈层状、似层状及透镜状,与地层整合产出,产状与围岩一致,并与围岩发生同步褶曲。 矿石以单锌矿石为主,其次为铅锌混合矿石,单独的铅矿石比较少见。矿石矿物成份主要为闪锌矿,次为方铅矿。矿石构造主要有浸染状构造、层块状构造,其次为条带状构造、层纹状构造、脉状构造、角砾状构造。围岩蚀变类型主要有硅化、绿泥石化、绢云母化、黄铁矿化等。一般矿体的顶、底板围岩蚀变不对称,以底板强烈蚀变为特征。 本区的钠长石岩、硅质岩等为热水沉积岩与铅锌矿床关系密切。矿石与这些热水沉积岩在微量元素、硫同位素、氢、氧同位素、铅同位素、稀土元素组成等地球化学特征方面比较相似,而明显区别于一般正常沉积岩。 本区铅锌矿床属热水沉积—改造成因,成矿金属物质主要来源于盆下基底岩石和地层深部,硫来源于海水硫酸盐还原硫,成矿流体主要为下渗海水。成矿模式为:地下含矿热水循环对流—沿同生断裂发生海底喷流沉积成矿—构造热液叠加改造富集。 本文重点分析了旬北地区志留系铅锌矿床的成矿规律,认为地层层位、同生断裂、前寒武系基底和三级沉积盆地控制了铅锌矿带的形成与展布,成矿环境突变界面、成矿流体性质演化界面、成矿流体—环境作用界面、后期构造、热液改造界面等地球化学界面控制矿体定位,同沉积洼地、砂泥岩界面发育层位、层内断裂与含矿层叠加地段和热液蚀变发育地段是铅锌矿的富集地段,热水沉积成矿作用之后的构造作用和热液活动对早先形成的铅锌矿体具有进一步的改造富集作用。同时,作者还提出了本区的时空边缘成矿体系,认为扬子板块北部边缘控制南秦岭成矿带,三级盆地边缘和同生大断裂边缘控制旬北地区铅锌矿带,铅锌矿床受岩性段层面和背斜等构造控制,而不同的岩石界面控制了铅锌矿体。 最后,总结了区域志留系铅锌矿的找矿标志,分析认为汉江南岸、双河地区、白河县黄石板铅锌矿区以西地区和安康一带具有进一步的找矿前景。更多还原

【Abstract】 In recent years, a series of lead-zinc deposits were explored in Silurian strata in the north area of Xunyang County. Through summarize the geological and geochemical characteristics of these lead-zinc deposits, The paper mainly research it’s metallogenic regularity and propose the exploration direction in this area in the future.From north to south, the Silurian lead-zinc deposits in this area can be divided into 3 mineralized zones, they are Sirengou-Nanshagou lead-zinc mineralized zone, Hongtupo-Hanshigou-Xiaogou lead-zinc mineralized zone and Xiying-Huangshiban lead-zinc mineralized zone.These lead-zinc deposits locate in some fine detrital stones, the ore bodies are beded and pod-like, they have the same occurrence and fold curve with there country rocks.Most of ore is zinc ore, then is lead-zinc ore, and the lead-ore can be found very rarely. The main mineral composition of the ore is zinc blende and lead glance. The ore have disseminated structure, stratified structure, stipped structure, lamellar structure, vein structure and brecciated structure. The alteration types of the country rocks are silicification, chloritization, sericitization and pyritization. Usually the country rock alteration of the floor and the roof of the ore body are not same, it has the character that the floor of the ore body has strong country rock alteration.The rocks such as albitite and silicalite are hydrothermal sediment rocks, they have the same character with the lead-zinc ore deposits in the geochemistry, such as the microelement, the sulfur isotope, the hydrogen and oxygen isotope, the lead isotope , the rare earth element composition, and so on, so they are different from the sedimentary rocks.The genesis of these lead-zinc deposits are hydrothermal sedimentation-reformation type, the ore-forming metals come from the basement under the basin, the sulfur come from the sulfate in seawater, and the mineralization fluid was the seawater which come into the basement under the basin. The metallogenic model was: the hydrothermal ore-forming solution convection under the basin, they come into the sea through thesynsedimentary faults and formed lead-zinc ore beds, at late the tectonic movement and hydrothermal solution reform the lead-zinc ore beds.The paper analysed the metallogenic regularity of Silurian lead-zinc deposits in the north area of Xunyang County, and consider the strata, synchronous faults, the basement before Cambrian system and the third class sedimentary basin were the main factor who cortrol the forming and the distributing of the lead-zinc minerallized zones. The geochemical interface, such as environment break interface, fluid evolution interface, fluid environment interaction interface, tectonic movement and hydrothermal solution actvation interface were the interspaces which the ore bodies formed in. The syndeposition potholes, the interfaces between sandrock and mudrock, the interlayer faults and hydrothermal alteration belts enriched these lead-zinc deposits. The hydrothermal solution and tectonic movements after the mineralizing process reformed and enriched these lead-zinc deposits. At the same time, the author point out that there are space-time marginal metallogenesis system in the research area, the north margin of YangZi plate cortrolled the mineralized zones of South Qinling area, the margin of the third class basin and synsedimentary fault cortrolled the lead-zinc mineralization in the area of Xunyang county, the boundaries between different strata and the anticlines cortrolled the forming of the lead-zinc deposits, the lead-zinc ore bodies formed in the interfaces of different rocks.In the end, the author summarize the indicator about the Silirian lead-zinc deposits, and consider in the south area of Hanjiang river, the area of Shuanghe in Xunyang county, the west area of Huangshiban in Baihe county and the area near by Ankang city have great foreground in ore rearch in the future.更多还原