M. Alexandra Skewes

Research Associate
Department of Geological Sciences - CB 399
University of Colorado, Boulder, Colorado 80309
(skewes@colorado.edu)

I am a petrologist/economic geologist with interest in the relation between metallogenesis, magmatism and tectonics, and also mineral economics and environmental issues related to the mining industry. I have worked on projects concerning  petrology of various hydrothermal ore deposits, including Cu-Mo porphyry and breccia, Au-Ag epithermal and Cu-stratabound deposits by way of fluid inclusions, stable isotopes and other geochemical techniques. 

Education:
Ph.D., Department of Geological Sciences, University of Colorado, 1992.
M.S., Department of Geological Sciences,  University of Colorado, 1984.
Título de Geólogo, Departamento de Geología, Universidad de Chile, 1980.

 PUBLICATIONS

 Papers:

Stern CR, Moreno H, Lopez-Escobar L, Clavero JE, Lara LE, Naranjo JA, Parada MA, Skewes MA. 2007. Chilean Volcanoes. In: Moreno T, Gibbons W (eds) The Geology of Chile, Geological Society of  London, Chapter 5, pp 149-180.

Skewes, M.A., A. Arévalo, R. Floody, P. Zuñiga, and C.R. Stern, 2006. The El Teniente megabreccia deposit, The worlds largest copper deposit. In “Super Porphyry Copper & Gold Deposits - A Global Perspective”. (T.M. Porter, ed). PGC Publishing, Adelaide, Australia. Vol, 1 p. 83-113.

 Stern, C.R. and Skewes, M.A., 2006. Origin of giant Miocene and Pliocene Cu-Mo deposits in central Chile:  Roles of ridge subduction, decreased subduction angle, subduction erosion, crustal thickening, and long- lived batholith size, open-system magma chambers. In “Super Porphyry Copper & Gold Deposits - A Global Perspective”. (T.M. Porter, ed). PGC Publishing, Adelaide, Australia. Vol, 1 p. 65-82.
 
Skewes, M.A., C.R. Stern, and C. Holmgren, 2003. The Donoso Copper-rich toumaline-bearing breccia pipe  in central Chile: petrologic, fluid Inclusion and stable isotope evidence for an origin from magmatic fluids  Mineralium  Deposita 38: 2-21, DOI: 10.1007/00126-002-0264-9.
 
Skewes, M.A., A. Arévalo, R. Floody, P. Zuñiga, and C.R. Stern, 2002. The giant El Teniente breccia  deposit: hypogene copper distribution and emplacement. In: “Global Exploration 2002- Integrated Methods of Discovery” (R. Goldfarb, ed.) Society of Economic Geologist Special Publication No.9, p.299- 332.
 
Vargas, R.,  L. Gustafson, M. Vukasovic, E. Tidy and M.A. Skewes. 1999. Ore breccias in the Río Blanco- Los Bronces porphyry copper deposit, Chile. In: "Geology and Ore Deposits of the Central Andes" (B.J. Skinner, ed.) Society of Economic Geologist Special Publication No. 7, p. 281-297.
 
Skewes, M.A., and C.R. Stern.  1996. Late Miocene Mineralized breccias in the Andes of Central Chile: Sr- and Nd-isotopic evidence for multiple magmatic sources. In "Andean Copper Deposits" (F. Camus, R. Sillitoe and R. Petersen, eds).  Society of Economic Geologist Special Publication No. 5 , p. 33-42.
 
Serrano, L., R. Vargas, V.  Stambuk, C. Aguilar, M. Galeb, C. Holmgren, A. Contreras, S. Godoy, I. Vela, M.A. Skewes, and C.R. Stern. 1996. The late Miocene to early Pliocene Río Blanco-Los Bronces copper deposit, central Chilean Andes. In: "Andean Copper Deposits" (F. Camus, R. H. Sillitoe and R. Petersen). Society of Economic Geologist Special Publication No. 5, 119-130.
 
Skewes, M.A. and C.R. Stern. 1995. Genesis of the giant Late Miocene to Pliocene Cu deposits of Central 
Chile in the context of Andean magmatic and tectonic evolution. International Geology Reviews, vol. 37, p. 893-909.
 
Skewes, M.A., and C.R. Stern. 1995. Genesis of the giant Late Miocene to Pliocene Cu deposits of Central  Chile in the context of Andean magmatic and tectonic evolution. Proceedings, Symposium on Giant Ore Deposits II, Queen's University, Kingston,  April 1995, p. 38-56.
 
Stern, C.R. and M.A. Skewes. 1995. Miocene to present magmatic evolution at the northern end  of the Andean Sourthern Volcanic Zone, Central Chile. Revista Geológica Chilena. vol. 22, p. 261-272.
 
Skewes, M.A., and C.R. Stern. 1994. Tectonic trigger for the formation of late Miocene Cu-rich
breccia pipes in the Andes of central Chile. Geology, v. 22, p. 551-554.
 
Skewes, M.A., and C. Holmgren, 1993. Solevantamiento andino erosión y emplazamiento de Brechas
 mineralizadas en el depósito de cobre porfídico Los Bronces, Chile Central (33°S): Aplicación de
 geotermometría de inclusiones fluídas. Revista Geológica de Chile, v.  20, p. 71-83.
 
Camus, F., and M.A. Skewes, 1991. The Faride epithermal silver-gold deposit, Antofagasta Región, Chile.
Economic  Geology, v. 86, p. 1222-1237.
 
 Camus, F., R. Boric, M.A. Skewes, J.C. Castelli,  E. Reichhard, and A. Mestre, 1991. Geology, petrology and
  fluid inclusions from the El Bronce gold deposit, Chile. Economic Geology, v. 86, p. 1317-1345.
 
Stern, C.R., M.A. Skewes, S. Saul, and K. Futa, 1989. Garnet peridotite xenoliths from the Pali-Aike basalts
 of southernmost South America. In: "Kimberlites and Related Rocks - Their Mantle and Crustal Setting" Geological Society of Australia Special Publication 14, v.  2, p. 735-744.
 
Holmgren, C., M. Marti, M.A. Skewes, A. Schneider, and R. Harmon, 1988. Análisis isotópicos y de inclusiones fluídas en el yacimiento Los Bronces, Chile Central. Actas V Congreso Geológico Chileno.  v. 1, B299-313.
 
Skewes, M.A., and F. Camus, 1988. Inclusiones fluídas y mecanismos de  precipitación de  metales preciosos  en el depósito epitermal de oro El Bronce de Petorca. Revista Geológica de Chile, No. 15, p. 31-39.
 
Stern, C.R., K. Futa, S. Saul, and  M.A. Skewes, 1986. Nature and evolution of the subcontinental mantle lithosphere below southern South America and implications for Andean magma genesis.  Revista Geológica de Chile, v. 27, p. 41-53.
 
Camus, F., R. Boric, and M.A. Skewes, 1986. El distrito de oro El Bronce y su relación con la caldera Morro
       Hediondo, Región de Valparaiso, Chile. Revista Geológica de Chile, v. 28, p. 95-101.
 
Hervé, F., and M.A. Skewes, 1986. Termobarometría en el complejo metamórfico de Scotia
       Cabo Lookout, isla Elefante. Serie Científica del Instituto Antártico Chileno, v. 34, p. 34-47.
 
Skewes, M.A., and W. Atkinson Jr., 1985. Petrology of the early formed hydrothermal veins within the central potassic alteration zone of the Los Pelambres porphyry copper deposit, Chile. Revista Geológica de Chile, v. 25-26, p. 39-56.
 
Skewes, M.A., 1985. Biotitas en la zona de alteración potásica del depósito de cobre porfídico
 Los Pelambres. Actas del Cuarto Congreso Geológico Chileno, v. 2, p. 342-353.
 
Stern, C.R., K. Futa, S. Saul, and M.A. Skewes, 1985. Ultramafic xenoliths found in the Pali-Aike basalts: their
       implications for the nature of the mantle below southern South America. Actas del Cuarto Congreso
       Geológico Chileno, v. 3, p. 380-412.
 
Skewes, M.A.,1980. Geología, petrología, químismo y origen de los volcanes del  área de Pali-Aike,
Magallanes, Chile. Anales del Instituto de la Patagonia, v. 9, p. 95-106.
 
Skewes, M.A. and C.R. Stern, 1979. Petrology and geochemistry of alkali basalts and ultramafic inclusions
from the Pali-Aike volcanic field in southern Chile and the origin of the Patagonian lavas. Journal of
 Volcanology and Geothermal Research, v. 6, p. 3-25.
 
Stern, C.R., M.A. Skewes, and M. Durán, 1976. Volcanismo calco-alcalino en Chile Austral. 
 Actas del Primer Congreso Geológico Chileno, v. 2, p. 195-212.

Selected Abstracts in the last 10years:


Seguel, J. Arévalo, A. and Skewes, M.A. 2006. Complejo de Brechas Hidrotermales en el Flanco Este de  Mina  El Teniente.  XI Congreso Geológico Chileno, Antofagasta. Extended  Abstract.. Actas, vol. 2, p. 351-354. Antofagasta, Chile.  
Skewes, M.A. and C.R. Stern, 2005. Magma genesis and mineralization of giant Miocene and Pliocene megabreccia deposits in the Andes of central Chile. GSA Salt Lake City Annual Meeting (October 16- 19),  Session No. 65, Abstracts with Programs Vol. 37, No.7.
 
Funk, J.A., Stern, C.R., Skewes, M.A. and A. Arévalo, 2005. Plutonic rocks containing primary igneous anhydrite in the El Teniente Cu deposit, Chile. GSA Salt Lake City Annual Meeting (October 16-19),  Session No. 65, Abstracts with programs Vol. 37, No.7.
 
Skewes, M.A. and C.R. Stern. 2004. Distinctive features and genesis of giant Miocene and Pliocene Cu-Mo  megabreccia deposits in the Andes of central Chile compared to smaller more typical  Cu-porphyries. International Association of  Volcanology and Chemistry of the Earth’s Interior (IAVCEI),  Pucón, Chile. CD ROM Symposium 1-C, No. 5
 
Funk, J.A., Stern, C.R., Skewes, M.A. and A. Arévalo. 2004. Plutonic Rocks Containing Primary Igneous Anhydrite in the El Teniente Cu Deposit, Chile. International Association of Volcanology and Chemistry of  the Earth’s Interior (IAVCEI), Pucón, Chile. (IAVCEI), Pucón, Chile. CD ROM Symposium 1-C, No. 3.
 
Skewes, M.A., C. Holmgren, and S. González, 2003. Ages and duration of brecciation and  mineralization
 events in the giant Miocene and Pliocene Río Blanco-Los Bronces copper deposit of central Chile.  Noveno Congreso Geológico Chileno, Concepción. Abstract CD ROM, Concepción, Chile.
 
Skewes, M.A. and C.R. Stern. 2003. Miocene and Pliocene Copper Megabreccia Deposits in the Andes of Central Chile: Geology and Genesis. Invited Abstract. Noveno Congreso Geológico Chileno,  Concepción. Abstract CD ROM, Concepción, Chile.
 
Stern, C.R. and M. A. Skewes, 2003. Adakite-like felsic porphyries in the giant Miocene and Pliocene copper deposits of central Chile: their petrogenesis and their role in the formation of these giant deposits Resumenes, Noveno Congreso Geológico Chileno, Abstract CD ROM, Concepción, Chile.
 
Hattori, K., J.C.M. DeHoog, J.D. Keith, M.A. Skewes, and C.R. Stern, 2003, Oxidized, S-rich mafic magmas for giant Cu mineralization: Evidence from Pinaubo, Bingham Canyon and El Teniente. Geological  Association of Canada- Soc. Economic Geologist Meeting, Vancouver, vol. 28, Abst-no. 453
 
Stern, C.R. and M.A. Skewes. 2002. Role of mantle-derived mafic magmas in the generation of the giant Miocene and Pliocene copper deposits of central Chile. GSA Denver Annual Meeting (October 27-30), 2002), Session No. 36.
 
Skewes, M.A., A. Arévalo, R. Floody, P.H. Zuñiga and C.R. Stern, 2002. Mafic magmatism associated with the genesis and evolution of El Teniente copper deposit, Chile. GSA Denver Annual Meeting (October 27-30), 2002), Session No. 36.
 
Skewes, M.A., A. Arévalo, C. Holmgren, and C.R. Stern, 2001. Stable isotope evidence for formation from  magmatic fluids of the mineralized breccias in the Los Bronces and El Teniente copper deposits, central Chile. III Simposium Sudamericano de Geología Isotópica. Extended Abstracts, CD ROM, p.531-534.
      
Skewes, M.A., and A. Arévalo , 2000. El complejo de gabros y diabasas que hospedan a las Brechas mineralizadas del depósito de cobre El Teniente, Chile Central. Extended Abstract. Resumenes  Ampliados del Noveno Congreso Geológico Chileno, Puerto Varas, Actas, vol I, p. 380-384.
 
Skewes, M. A., A. Arévalo, R. Floody, and P. Zuñiga, 1999. El Teniente (Braden) copper deposit in the Andes of Central Chile.  Geological Society of America, Denver, Colorado. Abstracts with Programs v.3, no. 7, p. A93.

Skewes, M.A., and A. Arévalo , 1997. "Andesitas de la Mina" El Teniente. Extended Abstract. Resumenes  Ampliados del Octavo Congreso Geológico Chileno, Antofagasta, Actas, vol III, p.1162-1164.