淮南潘集矿区奥陶系角砾岩发育特征及成因

Development Characteristics and Genesis of Ordovician Breccia in Huainan Panji Mines

为探讨华北板块南缘的奥陶系古岩溶成因,进一步为矿山岩溶水害防治提供基础研究和依据,以华北煤田南缘的淮南潘集矿区为对象,采用岩芯描述、观测统计、薄片分析等方法,对区内奥陶系角砾岩厚度、结构特征及分布规律进行系统研究,并探讨成因。结果表明,岩溶角砾岩距基岩面深度为350.4~1557.3m,呈三层状不等间距分布,平均厚度为4.9m、6.2m、7.8m;岩溶角砾段的角砾含量为30%~50%,粒径为3~90mm,主要为白云质灰岩、白云岩和灰质白云岩等岩屑,角砾岩屑中主要矿物成分为白云石颗粒,其次为微晶-隐晶质方解石,裂隙多被方解石脉充填;按成因可分为沉积间断期所形成的同生角砾岩和加里东运动抬升后经长期风化剥蚀及岩溶作用所形成的后生角砾岩,并提出对应的发育模式。

In order to explore the origin of Ordovician paleokarst in the southern margin of North China Plate and further provide basic research and basis for the prevention and control of karst water disasters in mines,this paper,taking the Huainan Panji mines in the southern margin of North China coal field as the object,analyzed the thickness,structural characteristics and distribution of Ordovician breccia in Panji mines systematically with some methods for core description,core observation and thin section analysis,and discussed its genetic mechanism.The results showed the following facts.The depth range of buried karst breccia from bedrock surface was from 350.4 to 1557.3m with a three-layer unequal spacing distribution,and the average thickness was 4.9m,6.2m and 7.8m respectively.The content of breccia in the karst section was from 30%to 50%with the particle size from 3mm to 90mm,and their main components was dolomite limestone,dolomite and limestone dolomite.The main mineral composition was dolomite particles,followed by microcrystalline-cryptic calcite,and the fractures were mostly filled with calcite veins.According to the genesis,it could be divided into the syngenetic breccia formed in the sedimentary discontinuous period and the epigenetic breccia formed by long-term weathering,denudation and karstification after Caledonian movement and uplift,with the corresponding development modes proposed.