1. 1 Geological Engineering Program, Faculty of Sciences and Engineering, Pontifical Catholic University of Peru (PUCP), Av. Universitaria 1801, San Miguel, Lima 15088, Peru
2. 2 Nevada Bureau of Mines and Geology, University of Nevada, Reno, Nevada 89557, USA
3. *Present address: BRGM–French Geological Survey, F-45060 Orléans, France.
4. 3 Department of Earth Sciences, ETH Zürich, 8092 Zürich, Switzerland
5. 4 Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, Switzerland
6. 5 ANDES C&P, Lima, Peru
7. 6 Departament de Mineralogia, Petrologia i Geologia Aplicada, Facultat de Ciències de la Terra, Universitat de Barcelona, Martí i Franquès s/n, 08028 Barcelona, Spain