NMT SEG Student Chapter Field Trip Report
NMT SEG Student Chapter Field Trip Report
NMT SEG Student Chapter Field Trip Report
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Solfatara-Group
<strong>SEG</strong> <strong>Student</strong> <strong>Chapter</strong>s <strong>Field</strong> Course<br />
Ore Districts of Northern Chile<br />
18-25 February, 2012<br />
The New Mexico Institute of Mining and Technology <strong>SEG</strong> <strong>Student</strong> <strong>Chapter</strong> organized<br />
a six-day, multi-student chapter collaborative field course highlighting various ore districts and<br />
mineralization styles of northern Chile. The field course was led by Dr. William X. Chávez, Jr.<br />
of New Mexico Tech and Dr. Erich U. Petersen of University of Utah. Participants consisted of<br />
two industry professionals from Perú, ten graduate students, and five undergraduate students.<br />
Our field course began at the La Coipa high sulfidation epithermal system in the<br />
Maricunga District near Copiapó. Jack Pritting and Claudio Ahumada of Kinross provided<br />
discussions dealing with the mineralogy of the La Coipa epithermal system as we examined core<br />
from several prospects in the La Coipa area. We also visited several field areas in which<br />
solfatara-style alteration, including surface exposures abundant native sulfur, gave rise to<br />
discussions of the importance of recognizing shallow-level alteration associated with welldeveloped<br />
epithermal systems.<br />
The Punta del Cobre breccia-manto system, characterizes Cu-(Au) mineralization<br />
styles in this venerable district. Chief Geologist Radu Almasán discussed alteration assemblages<br />
as we reviewed and identified ore and alteration minerals from several properties in the district.<br />
While reviewing core we used activity diagrams to help explain copper mineralogy, and the main<br />
alteration mineral assemblages.<br />
The Altamira Cu-Ag mine is part of an historic district comprising both underground<br />
and open pit mines; mine geologists Leonardo Retamál F. and Gerardo Garrido S. discussed<br />
the geology of the Cretaceous hostrocks and the high-grade copper-silver sulfides. During the<br />
visit we discussed copper systems hosted by volcanic rocks and how low-temperature redox<br />
conditions and structural components control ore mineralization.<br />
The high sulfidation Au-(Cu-As) epithermal system at El Guanaco was introduced to<br />
our group by Geology and Exploration Manager Christián Cubelli B., and we were able to<br />
compare El Guanaco to the La Coipa epithermal system and their geochemical variations.<br />
Our visit to the world largest copper mine at the La Escondida property allowed us to<br />
explore their Baker prospect, with discussions and a detailed presentation by Senior Exploration<br />
Geologist Chilong Wong and Exploration Manager Javier Urrutia F. We discussed porphyry<br />
systems and exploration considerations for large hydrothermal systems, supergene processes, and<br />
ore system structural controls. Review of core samples provided the opportunity to discuss ore<br />
assemblages and their relationships to specific alteration minerals, and the relationships between<br />
vein types, and ore mineral paragenesis.
Our last visit was to the Sierra Miranda Cu-Ag district, lead by Javier Pinto C.<br />
During the visit we discussed andesite-hosted copper sulfide systems, supergene mobility of<br />
copper, and the strong structural control of copper oxides.<br />
We wish to thank all of the mines for taking the time to host our visits, the professional<br />
geologists who attended the course as mentors, and Dr. William X. Chávez, Jr. and Dr. Erich<br />
Petersen for their leadership and vast knowledge of the ore districts. We would also like to thank<br />
New Mexico Tech and Dr. William X. Chávez, Jr. for financial support for this field course.<br />
List of field course participants<br />
- Dr. William X. Chávez, Jr., New Mexico Institute of Mining & Technology<br />
- Dr. Erich Petersen, University of Utah<br />
- Edgar Espinoza, Teck Corporation<br />
- Juan Javier Canales Quispe, Milpo<br />
- Maureen Moore-Roth, New Mexico Institute of Mining & Technology<br />
- Andrea McHugh, New Mexico Institute of Mining & Technology<br />
- Rebecca Morris, New Mexico Institute of Mining & Technology<br />
- Zachary Vance, New Mexico Institute of Mining & Technology<br />
- Allison Severson, University of Minnesota Duluth<br />
- Matt Manor, University of Minnesota Duluth<br />
- Michael Buschette, University of Minnesota Duluth<br />
- Nick Kerr, Colorado School of Mines<br />
- Wesley Hall, Colorado School of Mines<br />
- Erik Tharalson, Colorado School of Mines<br />
- Craig Fleming, Colorado School of Mines<br />
- Theresa Zajac, University of Utah<br />
- Patrick Loury, University of Utah<br />
- Katie Bradbury, University of Utah<br />
- Daniela Anguita, University of Utah
Punta del Cobre Ore Pile