秘鲁位于南美洲西岸,作为安第斯成矿带的重要组成部分,矿产资源丰富,铜矿资源储量和产量位居世界第二。本文首次对秘鲁开展全国范围全球尺度地球化学调查工作,获得汇水域沉积物样品共416件,秘鲁全境铜元素含量为2.38~495 μg/g,背景值(中位数)为24.0 μg/g。秘鲁全境、沿海带、安第斯山区和亚马孙平原的表层(深层)汇水域沉积物中铜元素平均含量依次为31.4(31.6)、45.6(32.2)、47.5(48.2)和21.3 μg/g(24.9 μg/g)。地球化学图显示,秘鲁铜空间分布整体呈现出西高东低的趋势,西部沿海带和中部安第斯山区含量较高,东部亚马孙平原区含量较低的特征。本文选用75%累积频率作为异常下限值,圈定出5处铜地球化学异常,其中两处达到地球化学巨省规模,两处达到地球化学域规模。同时,讨论铜地球化学异常的来源和影响因素,解析与之对应的矿产资源响应,秘鲁良好的构造演化环境,为大型、超大型铜矿床的形成提供有利条件。太平洋纳斯卡板块向南美大陆不断俯冲变换,致使洋壳发生部分熔融,产生强烈而广泛的中酸性岩浆活动,且岩浆中铜含量大规模富集,局部地区在特定环境下富集成矿。这一构造运动导致铜元素在秘鲁空间分布上呈现出多个地球化学块体,可能也是铜地球化学异常形成的原因之一。这些巨大的地球化学块体发现可用于未来寻找铜矿集区或大型、超大型铜矿床,圈定找矿远景区,并可以降低找矿风险,提高找矿效率,缩短找矿周期。研究圈定的地球化学找矿远景区,可为秘鲁铜矿勘查开发利用提供基础资料和数据。

Peru, as an important part of the Andean metallogenic belt, is located on the west coast of South America. It is rich in mineral resources, and its copper reserves and copper production ranks second in the world. This paper carried out a global scale geochemical mapping project in Peru for the first time, and obtained a total of 416 catchment sediment samples. Copper contents in catchment sediments in Peru ranged from 2.38 to 495 μg/g, with a background (median) value of 24.0 μg/g. The average copper content in the surface (deep) catchment sediments of the whole Peruvian region and of the coastal zone, the Andes mountains and the Amazon plain were 31.4 (31.6), 45.6 (32.2), 47.5 (48.2) and 21.3 (24.9) μg/g (μg/g), respectively. The geochemical map showed that the spatial distribution of copper in Peru as a whole had a trend of high in the west and low in the east, with higher copper content in the western coastal zone and the central Andes mountains and lower copper content in the eastern Amazon plain. Using a cumulative frequency of 75% as the lower limit of anomaly, five copper geochemical anomalies were delineated, two of which reached the scale of geochemical giant province, and another two of geochemical province. The paper also discusses the source and influencing factors of copper geochemical anomaly and the impact on mineral resources. The favorable tectonic evolution environment of Peru provide favorable conditions for the formation of large and super-large copper deposits. The continuous subduction and transformation of the Nazca plate of the Pacific Ocean to the South American continent led to partial melting of the oceanic crust, resulting in strong and extensive medium-acidic magmatic activity. In addition, the copper content in the magma is enriched on a large scale, and the local area is enriched and metallogenic under specific environment. This tectonic movement led to several geochemical blocks in the spatial distribution of Cu elements in Peru, which may also be one of the reasons for the formation of Cu geochemical anomalies. In future studies these geochemical blocks can be used to search for copper ore concentration areas or large and super-large copper deposits, delineate prospective areas, reduce prospecting risks, improve the prospecting efficiency and shorten the prospecting period. Geochemical prospecting conducted in the research area can provide basic information and data for the exploration, development and utilization of copper deposits in Peru.