Abstract:

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.

Key words: Peru, copper, catchment sediment, geochemical mapping, metallogenic prospective area