浙江6702爆发角砾岩筒地质特征

GEOLOGICAL FEATURES OF No.6702 EXPLOSIVE BRECCIA PIPE IN ZHEJIANG

在揭露6702铀矿点的过程中，发现该矿点是处在一个典型的爆发角砾岩筒内，就着手进行研究，了解到岩筒具有一系列的隐蔽爆发特征。本文将对岩筒的形态、规模和产状，岩筒岩石特征和类型及岩相分带，岩筒与围岩接触关系，岩筒形成的地质时代，岩筒后期改造及成因进行探讨。

No. 6702 explosive breccia pipe, which occurred in intercrossing section between NE arc fault and NW fault, is located at southern margin of damaged volcanic vent formed in Northeastern part of baisa-shengong volcanic active belt.The shape of breccia pipe (a: b: c equals >300: >300: 150~200 (m) is irrebular elongated lens rake with near North. The components of explosive breccia with no separations are simple and changed with country rocks, and the configuration angle of breccia changed greatly with shape is clear, and breecias are majorly adhensive with the same components of rock debris together and with micro-explosive cataclastic structure. Brecciated degree which is stongerat up per or centre parts and weaker at lower or margin parts is unhomogenous. Rock types can be class fied by cataclastic degree, mother rocks and replacement strength. Breccia body exists petrographical facies separation in vertically and horizontally. The contacting relationship between rock pipe and country rock is formed with complicated explosive features. Geological epoch of rock pipe, which is slightly later than formed peried of subvolcanic rock body of rhyoporphyry, is at latest time of Ⅱ sub-cycle of volcanic active cycle at shouchang group period. Formed rock pipe which is upper-moved with NEE direction in south-eastern part by NW formed fault, is sep arated with major rock taly. The genesis of rock pipe is high temperature gas-liquid camounage explosive at epithermal-super-epithermal environments of magmat ic intrusive actions. Formed rock pipe is the avoilabli place for ore-bearing solution flow and precipitation.In conclusion, explosive breccia pipe is formed at special condition and with a series of camouflage explosive features.