The SearchMap software encourages experts to incorporate
personal knowledge and experience into decisions that involve multiple
layers of interdependent map information. The software has
been used to examine the spatial associations of gold group elements
(Au, Sb, As, Hg), potential host rocks for gold mineralization, topographic
lineaments, and level-sliced topography within a 58,000
km2 region along the ancient continental margin in eastern Nevada.
The region is host to 526 localities where gold has been reported,
100 localities of antimony, 59 of arsenic, and 82 of mercury. It also
contains the Carlin and Battle Mountain-Eureka gold trends, and
thus is a logical place to look for undiscovered gold. Discoveries
usually involve detailed mapping and drilling of a few square kilometers
area, but the goal of the present work is to demonstrate how
SearchMap can be used to select areas for which detailed evaluations
may be appropriate.
Twenty-two carbonate-bearing units ranging in age from
Cambrian through Triassic have been input as potential host rocks
for gold mineralization. Elevations that encompass many of the
upper pediment surfaces and mountain fronts also have been input,
as have three classes of topographic lineaments: Classes I and II
from the mountain ranges, and Class III from basins of the region.
All four of the gold group elements are strongly associated with NS
and NE trending Class I lineaments. Fewer element occurrences are
associated with the (older?) Class II lineaments, but NE and NS features
apparently were favored, as were EW lineaments. Occurrences
of gold group elements are sparse with respect to Class III lineaments
in basins of the region, but gold mineralization is associated
most closely with NE and EW trending features.
The spatial data have been integrated using linear and gaussian
filters and search parameters supplied by the writers for the 58,000
km2 region in eastern Nevada. The SearchMap calculated using the
linear filter highlights 4 km2 in which there is at least 65 percent
overlap of convolved exploration parameters. This number grows to
31.25 km2 in which there is >60 percent overlap, and a total of
289.75 km2 for >52 percent overlap. The latter area represents 0.5
percent of the region. The corresponding numbers for the
SearchMap calculated using the gaussian filter are 4 km2 for >65
percent overlap, 22.75 km2 for >60 percent, and a total of 198.50
km2 for >52 percent overlap (0.34% of the 58,000 km2 region).
These areas provide a focus for additional SearchMap analysis, and
for field evaluation.