秦岭地区水系沉积物和岩石金元素时空分布研究

Temporal-Spatial Distributions of Gold in Drainage Sediments and Rocks in the Qinling Region,China

为研究秦岭地区水系沉积物和岩石中金的地球化学时空分布及其与金矿集区的对应关系,分别收集了该区1︰20万区域化探扫面计划和全国地球化学基准计划的水系沉积物和岩石金分析数据,绘制了该区水系沉积物和岩石的金地球化学分布图。秦岭地区以水系沉积物金地球化学异常面积大于1000km^2为准,共圈定11处金的地球化学省,这些金的地球化学省同时也是金矿床密集产出的部位。水系沉积物金背景值较高的是西秦岭(2.11×10^(-9))和松潘-甘孜(2.27×10^(-9))造山带,同样这个构造带中岩石金的背景值也较高,分别为0.81×10^(-9)和0.70×10^(-9)。秦岭地区不同构造带中水系沉积物金背景值受岩石金背景值的制约。金的地球化学省是由高金背景的岩石,金矿化作用和金矿床次生风化作用相互叠加的结果。该研究对于了解巨量金元素聚集就位机制和聚焦找矿靶区具有重要意义。

In order to study the temporal-spatial distributions of gold in drainage sediments and rocks and their spatial relationship with known gold metallogenic districts in the Qinling region,geochemical distribution maps of gold in drainage sediments and rocks have been constructed in this paper based on the geochemical data collected from the 1： 200000 Regional Geochemistry-National Reconnaissance project and the China Geochemical Baselines project. Eleven gold geochemical provinces with the area of over 1000km^2 have been outlined. They are spatially consistent with the distribution of gold metallogenic districts in the region. There are relative high gold background values for drainage sediments and rocks in the west Qinling（ 2. 11×10^（-9）,0. 81×10^（-9）,respectively） and Songpan-Ganzi（ 2. 27×10^（-9）,0. 70×10^（-9）,respectively） two orogenic belts. The gold background values of drainage sediments are constrained by those of rocks in various tectonic belts in the Qinling region. The gold geochemical provinces could be resulted from the mutual superposition among the rock with high gold background value,gold mineralization,and secondary weathering of Au deposit. The study is significantly important to understand the mechanism of huge gold accumulation in position and to focus on prospecting targets.