Stewart R. Wallace — 1919–2009 - Society of Economic Geologists

JULY 2009 No 78 SEG NEWSLETTER 29
The fifth SEG Foundation Student-
Dedicated Field Course was held May
12–21, 2009, and dealt with review of
and visits to gold deposits of northern
Nevada. In a competitive process, 17
students representing 17 different universities
from nine countries were
selected to participate in the course.
The field course began in the Battle
Mountain district, where Regional
Geologist Fred Breit and Lisa Davenport
of Newmont Mining Corporation led
visits to the key structural zones within
the district and
discussed the significance
of mineralization
in the
Phoenix Cu-Au
project area; participants
reviewed
the local tectonostratigraphy
and
were introduced
to the importance
of understanding
the stratigraphic
and structural controls
of precious
and base metals
in the district.
Newmont also
hosted a two-day
visit to the Carlin
district, during
which Rachel
Burgess and
Amanda Izatt
spent a day reviewing important drill
core intervals with the students, emphasizing
the stratigraphy of the northern
part of the Carlin Trend. The second
day included an underground tour of
the of the Chukar mine, led by Alan P.
Sweide and Jennifer Hansom, followed
by visits conducted by Rachel Burgess
and Amanda Izatt to former open pit
mines that display local stratigraphic
relationships in the northern Carlin
Trend. The significance of the Roberts
Mountain Thrust and its tectonostratigraphic
importance in the Trend was
emphasized.
In the Cortez district, the Pipeline, Gold
Acres, and ADA52 open pits were visited.
Senior geologist Nancy Richter of
Barrick discussed the stratigraphy, the
changing stratigraphic unit names, and
� SOCIETY OF ECONOMIC GEOLOGISTS FOUNDATION �
STUDENT-DEDICATED FIELD COURSE – GOLD SYSTEMS OF NORTHERN NEVADA
May 12–21, 2009
William X. Chávez, Jr. (SEG 1990 F), and Erich U. Petersen (SEG 1986 F)
general settings of mineralized sedimentary
rock units within the various
mineralized areas of this venerable
old—and new—district. Senior geologist
Mark Bradley discussed various occurrences
of the Roberts Mountain Thrust
in the Gold Acres mine area, and
pointed out a substantial stratigraphic
interval—comprising most of a highwall
in the Gold Acres pit—that represents
the Thrust.
At the impressive Midas district,
senior geologist Michael Robinson,
along with Gabe Graf and J. P. Spring,
all of Newmont, provided reviews of
surface exposures in historic mine areas
and select core intervals, coupled with
an excellent series of visits to underground
exposures of the low-sulfidation
banded quartz veins that host bonanzagrade
Ag-(Au). The evening before visiting
Midas, Gabe Graf and Leann Giese
hosted an evening barbecue, during
which the group was given essential
safety and geologic presentations prior
to visiting the mine.
Continuing westward to the Getchell
Trend, the next stop was Newmont’s
very large Twin Creeks mine, where Pat
Donovan, Sue Abbott, and Anita Brown
reviewed the general geology and discovery
history of the Rabbit Creek and
Chimney Creek deposits. The field visits
included discussions on the importance
of faults and bedding deformation
structures, with were exceptionally well
exposed in the immense highwalls of
two open pits. Following the Twin
Creeks visit, Sue Abbott and Keith
Aitken graciously hosted a beer ‘n barbeque
for the group.
At the historic Getchell district,
Barrick senior project Geologist Keith
Wood, along with Dawn Martin and
Merilie Reynolds, discussed the evolving
stratigraphic relationships and ore controls
of the
Getchell and
Turquoise
Ridge ore
deposits and
an overlook of
the classic
range-front
fault system as
exposed in
numerous pits
hugging the
eastern margin
of the
Osgood
Range. Don
MacKerrow,
along with
Greg Dering,
provided backgroundgeol-
ogy, core
review, and
field visits to
the Preble area, where participants discussed
skarn development and structurally
controlled gold occurrences in
this area south of Getchell.
The final stop on the course was at
the Coeur d’Alene Mines Corporation
mine in the Rochester district, where
senior exploration geologist Henry
Follman discussed the historic background
and geology of this large silver
deposit, hosted by a series of rhyolitic
volcanic units and associated clastic
sediments. Structural control of the distribution
of silver sulfosalts, including
the development of breccias hosting
high-grade Ag (low Au) mineralization,
was emphasized. The current standby
status of this property was also dis-
Arriving at the airport, course participants assemble for a group photo before beginning their
visit to gold systems of northern Nevada.
cussed, as were the ongoing
reclamation
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STUDENT NEWS