湖南水口山矿田老鸭巢爆破角砾岩特征及成因初探

老鸭巢铅锌金多金属矿床中的岩体超覆侵入时形成了一系列角砾岩，其中岩浆隐蔽爆破角砾岩就是矿床铅锌金矿体主要赋矿构造.隐蔽爆破角砾岩可分为隐爆角砾、震碎角砾、流化角砾.老鸭巢矿区广泛分布着晚三叠世-中侏罗世的古岩溶沉积体，这些沉积的孔隙度高且富含地下水.当岩浆超覆侵入此处时，由于外部环境发生急剧变化，岩浆减压、降温、二次沸腾，并不断析出流体，在局部圈闭环境下流体压力将逐渐增大；加之岩溶中地下水丰富，地下水不断的气化，使气体的压力骤然增大.在屏蔽作用良好的超覆部发生了爆破作用形成了隐爆角砾；在爆破的外部震碎带形成了震碎角砾；而爆破之后的流化作用则形成了流化角砾.通过对老鸭巢爆破角砾岩的特征的研究，结合爆破角砾岩形成的地层、构造、岩体等条件的分析来探讨隐蔽爆破角砾岩的形成过程.分析了老鸭巢铅锌金矿体与隐蔽爆破角砾岩的关系，为今后矿山找矿提供服务.

CHARACTERISTICS AND ORIGIN OF THE LAOYACHAO CRYPTO-EXPLOSIVE BRECCIA IN SHUIKOUSHAN OREFIELD, HUNAN PROVINCE

A series of breccia was formed during the overlap intrusion in the Laoyachao Pb-Zn-Au polymetallic deposit.The magma crypto-explosive breccia,which is the main host of the deposit,includes crypto-explosive breccia,shatter breccia and fluidized breccia.The Late Triassic-Middle Jurassic karst sedimentary bodies,with high porosity and containing groundwater,are widely spread in the ore field.When the magma intrusion took place,the external environment changes caused the reduction of pressure and temperature,with re-boiling of magma and constant exhalation of fluid.In locally closed environment,the fluid pressure gradually increased.With rich groundwater in the karst rocks,continuous gasification of the groundwater resulted in rapid increase of gas pressure.In the well confined area by the overlap,explosion took place,forming crypto-explosive breccia.In the external zone of the explosion,shatter breccia was formed.The fluidization after the explosion,then,formed the fluidized breccia.Based on the study of the characteristics of the crypto-explosive breccia in the Laoyachao Pb-Zn-Au polymetallic deposit,with the rock formation,structure and intrusive rocks,the forming process of the crypto-explosive breccia is discussed.The analysis on the relationship between the lead-zinc-gold ore bodies and the crypto-explosive breccia will be helpful for further prospecting in the mining area.