开放成矿系统元素迁移负异常结构对深部找矿预测的意义

The Significance of Elemental Mass-transfer in Open Metallogenic System for Deep-buried Ore Prospecting

在开放体系成矿过程中,成矿信息应具有时间和空间两方面的属性。空间属性表现为元素在赋矿空间的分布及变化,时间属性则表现为成矿过程中元素的迁移变化。本文以安徽省兆吉口铅锌矿床为例,通过Grant方程进行元素质量迁移研究,建立Na2O负异常结构,并应用成分数据理论的双标图对负异常结构进行验证,结果发现负异常结构携带着时间维度上的成矿信息。成矿元素Pb、Zn的正异常分布于Na2O负异常范围内。Na2O与Pb、Zn、Au负相关,Au与Pb、Zn呈弱负相关,表明该地区可能存在与Pb、Zn同一成矿作用不同成矿阶段形成的Au矿化/体。兆吉口地区的找矿方向应为Pb、Zn、Au三种矿产资源。Na2O负异常在深部并未结束,表明深部仍可能存有矿体。

In any metallogenic system,ore-forming information has time and space attributes.The distribution and variation of elements in the ore-bearing space are information of the spatial attribute,whereas element mass-transfer during ore-forming processes is information of the time attribute.A case study has carried out on the Zhaojikou lead-zinc deposit in Anhui province.Grant equation was used to study the elemental mass-transfer and the Na2O negative anomaly structure was constructed.Then,the Na2O negative anomaly structure was confirmed by the biplot of the compositional data theory.The results showed that the negative anomaly structure carries ore-forming information of time dimension.The positive anomalies of ore-forming elements like Pb and Zn are distributed within the negative anomalies of Na2O.Na2O is negatively correlated with Pb,Zn and Au,whereas Au is negatively correlated with Pb and Zn.It is suggested that there may be an Au mineralization/body formed in the same ore-forming system but different stages.Therefore,besides Pb and Zn,Au should be one of the prospecting targets in the Zhaojikou area.In addition,the continuous Na2O negative anomaly in the deep may indicate possible occurrence of deep-buried ore bodies.