低密度地球化学填图在热带雨林区的适用性探索: 以印度尼西亚苏门答腊岛巴东明古鲁地区为例

Investigation of the Feasibility of Appling Low-density Geochemical Mapping in Tropical Rainforest Areas:A Case Study of Padang and Bengkulu Area in Sumatra,Indonesia

不同尺度地球化学填图能否获得稳定的和可追索的地球化学模式,能否真实反映元素含量背景,是检验填图方法是否可行的重要依据。笔者选择印度尼西亚苏门答腊岛巴东—明古鲁地区热带雨林区为研究对象,对比该区1:100万(1个样/100 km2)和1:25万(1个样/4 km2)两种不同比例尺的地球化学采样所获得的地球化学数据和异常分布模式,发现二者获得的元素含量背景值和中位数非常接近,所圈定的地球化学省在形态和变化趋势上非常类似,浓集中心的位置几乎完全重合,证明低密度地球化学填图也能获得稳定的和可追溯的地球化学模式,认为该方法在热带雨林区也是适用的。低密度地球化学填图圈出的地球化学省基本涵盖了研究区大的矿床和花岗岩体,真实的反映了研究区元素的分布情况,在这些地球化学省内开展更大比例尺的地球化学填图工作,能进一步圈定局部异常直接找矿,降低企业勘查投资风险。

Whether geochemical mapping at different scales could obtain stable and traceable geochemical patterns and whether it could truly reflect the background values of different elements are important for testing the feasibility of the selected geochemical mapping methods.The tropical rainforest of Padang-Bengkulu area in Sumatra,Indonesia was selected for this study,and the results from geochemical mapping at the scales of 1:1000000(1 sample/100 km2)and 1:250000(1 sample/4 km2)were compared in this area.Their background values,medians,and geochemical patterns obtained are very consistent.The geochemical provinces are very similar and reproducible by different sampling densities,and the concentration centers are overlapped,which indicates that the low-density geochemical mapping can obtain stable and traceable geochemical patterns and that this method is applicable in tropical rainforest areas.The geochemical provinces delineated by the low-density geochemical mapping cover the large ore deposits and granite bodies,and truly reflect the distribution of different elements in the study area.Geochemical mapping at a larger scale could be implemented in these geochemical provinces and many local anomalies could be delineated for exploration,which thereby reduces risks in exploration and investment.