Economic Geology; June 2005; v. 100; no. 4;
p. 689-705; DOI: 10.2113/100.4.689
© 2005 Society of Economic Geologists
Undulatory Silver-Rich Polymetallic Veins of the Castrovirreyna District, Central Peru: Fault Growth and Mineralization in a Perturbed Local Stress Field
James M. Wise
Department of Geological Sciences, University of Nevada-Reno, Reno, Nevada
89557
E-mail, jimxoso{at}yahoo.com
Strongly undulatory silver veins of the Castrovirreyna district, central
Peru, formed in a dilatant, anastamosing, low-displacement, left-lateral fault
system during late-Miocene, east-westdirected compression. The steeply
dipping veins have multiple orders of undulations, as seen in map view, and
underground mines expose strong dip reversals. Kinematic indicators from the
east-northeast to west-northweststriking veins record mainly left-lateral
slip and lesser oblique-reverse slip. These striation data, considered along
with vein intersection angles and map patterns, indicate that the veins did not
form as a simple conjugate fracture set. The preferred interpretation is that
the curved fracture growth and complex slip distributions developed because of
local stress-field modifications by the propagating faults and dilating vein
segments during regional east-westdirected compression. Variably oriented
fault striations, compound displacement profiles, and multiple scales of vein
curvature are all characteristics of stress interaction between subparallel
veins. Veins possessing these features may be expected to host oreshoots with a
complex geometry that depends not only on local accommodation space produced at
dilant jogs, but also on the proximity to other veins and changing slip
directions.
Copyright © 2009 by Society of Economic Geologists