甘肃玛曲大水金矿矿体地质数据中蕴涵的成矿信息

大水金矿是著名的超大型矿床，对于其地质地球化学特征已有许多较深入的研究，本文通过单因素直方图统计、关联分析、分形统计、曲线拟合等方法研究了矿体地质数据之间的关系。规模最大的主矿体与其他矿体相比，在顶板围岩、底板围岩、品位、矿体倾向、长度、延深等6个要素上均体现出奇异性，可见主矿体是在十分特殊的地质环境中形成的。控矿变量中，矿体长度、厚度、延深和倾向等变量之间具有相关性，倾向在20°~320°内变化，倾角、品位与其他变量之间的相关性不显著；由此推测，成矿作用的发生并不直接受控于浅层的构造因素，而与岩浆侵入及热液活动诱发的似环状、似锥状局部构造裂隙有关。矿体资源量具有明显的多重分形分布特征，而矿体的长度总体上呈简单分形分布，与前人的研究结果联系起来看，大吨位矿体的围岩以构造角砾岩或蚀变角砾岩为特征，属于充填成因；而中等规模的矿体则属于热液交代成因，一些小规模矿体可能与沉积作用有关；在成矿空间上，不同期次的成矿作用遵循了同位成矿规律。矿床的吨品位关系对幂律分布并不能很好地拟合，而是服从指数分布。

Genesis of the Dashui Gold Deposit in Maqu, Gansu Province: Evidence from Geochemical Analysis

Dashui gold deposit is one of the renowned superlarge gold deposits,numerious research has been done on its geochemical characteristics.The study focuses on correlation between all the data from all geological bodies using various geochemical means. Comparison of the largest orebody to other orebodies shows that they all show great differences in six geological factors such as country rock in the topwall and footwall,grade,dipping,length and depth,suggesting that main orebodies formed in a special environment. Ore-controlling variables such as length,thickness,depth and dipping are interrelated with dips ranging from 20 to 320. There is no distinct correlation among dipping angle,grade and other variables,suggesting that the deposit is not undirectly controlled by epizonal ore-controlling factors but related to local ring-like or taper-like structures resulted from magmtic intrusion and hydrothermal activities. Compared to previous results,country rocks around large-tonnage orebodies are characterized by structural breccia or altered breccia,which indicates filling genesis. Medium-scale orebodies resulted from hydrothermal metasomatism. Small-sized orebodies are probably related to sedimentation. Spatically,various mineralizations are subject to the law of isospatial metallogenesis. The relation of tonnage to grade in the deposit is subject to exponential function,rather than power function.