A review of hydrogeochemical mineral exploration in the Atacama Desert, Chile

• Published in: Ore geology reviews Vol. 124; p. 103562
• Main Authors: Kidder, J.A., Leybourne, M.I., Layton-Matthews, D., Bowell, R.J., Rissmann, C.F.W.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2020
• Subjects: Atacama; Chile; Concealed orebodies; Epithermal; Groundwater; Hydrogeochemistry; Mineral exploration; Mineral exploration in covered terrains; Porphyry-copper; Sinks; Solutes; Sources; Stable isotopes; Strata-bound; Trace elements; Sinks; Strata-bound; Solutes; Atacama; Sources; Hydrogeochemistry; Groundwater; Mineral exploration; Stable isotopes; Concealed orebodies; Mineral exploration in covered terrains; Trace elements; Chile; Porphyry-copper; Epithermal
• ISSN: 0169-1368; 1872-7360
• DOI: 10.1016/j.oregeorev.2020.103562

[Display omitted] •Differentdeposit types are defined by distinct hydrogeochemical footprints.•Seven highly differentiated solute sources are documented in the literature.•Significant variation in physiochemistry and salinity is observed between the different solute sources.•Trace element tracers are useful for differentiating solute sources and ore body vectoring.•Stable isotopes of groundwaters provide additional vectoring and fingerprinting tools. An abundance of world-class copper deposits in the Atacama region of northern Chile has made Chile the world’s leading copper producer. However, despite extensive exploration activities, the region remains a conundrum, with mature outcropping exploration plays juxtaposed with largely unexplored, extensive areas of post-mineral cover. This scenario offers exciting mineral exploration opportunities in the highly prospective and well-endowed, but locally concealed, metallogenic belts of northern Chile. Conventional exploration of local vast gravel plains or ignimbrite cover in northern Chile are hindered by the ineffectiveness of traditional geochemical techniques in covered settings and the commonly uneconomical costs associated with the systematic use of geophysics and extensive grid drilling. Porphyry deposits of the Atacama region have served as a test case for the use and testing of the effectiveness of hydrogeochemistry and isotopic vectoring in base metal exploration, with a comprehensive set of mineral exploration case studies, including examples of porphyry, epithermal and strata-bound deposits in Chile. Despite previous pilot studies, hydrogeochemistry remains a tool underutilized tool by many explorers, presumably due to a perception that sampling is challenging and laborious, and that data interpretation is intricate and complicated. Here we present a compilation of historical and current case studies to provide an overview of the most likely solute sources and sinks in the hyper-arid Atacama Desert as well as the resulting potential hydrogeochemical signatures that can be expected and their interpretation. The objective of this study is to provide a guide for the interpretation of hydrogeochemical exploration datasets.