Mapeo hidrogeoquímico regional con muestras de aguas superficiales en la cuenca Chancay-Lambayeque, Norte del Perú: procesamiento estadístico e interpretación de anomalías

Abstract

Hydrogeochemistry as a mineral exploration tool is used in several mining districts from Chile or Canada to generate geochemical signatures of water by interaction with the surface and underground geological environment. This regional hydrogeochemical mapping investigation used a surface water sampling database from the Chancay-Lambayeque basin in Northern Peru provided by the Geological Survey of Peru (INGEMMET) with the objective of generate new zones for mineral exploration using univariate, bivariate, multivariate (PCA) statistical methods, hydrogeochemical diagrams and geostatistical interpolation by ordinary kriging (OK). Univariate statistical analysis determined statistical parameters such as measures of central tendency, measures of shape, and ranges of background, threshold and geochemical anomalies (for example: Cu with strong anomalies between 0.89 to 2.54 mg/L), while bivariate correlation defined geochemical associations (for example: Ba - Mo, etc.) and multivariate analysis by Principal Component Analysis (PCA) generated 4 PCA's representing multivariate associations such as PCA1 related to Epithermal mineralization or PCA3 related to distal mineralization of Porphyry Cu-Mo. In addition, the use of hydrogeochemical diagrams resulted hydrogeochemical characteristics such as types of waters or mechanisms that control the chemical composition of the water, allowing the interpretation of two groups of surface waters. The geostatistical analysis of the main variables and PCA’s facilitated the interpolation by ordinary kriging (OK) method with the objective to identify the location of the anomalies, as well as allowing their interpretation using geological-geochemical sections. Finally, the interpretation of the results generated 17 anomalous zones, highlighting 11 new zones for mineral exploration.