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

JULY 2009 No 78 SEG NEWSLETTER 25
Society of Economic Geologists
U2009 Field Course –
Uranium Deposits of the Colorado Plateau
May 6–10, 2009
In conjunction with the U2009 conference
in Keystone, Colorado, the Society
of Economic Geologists organized a
four-day field course dealing with sandstone-hosted
uranium deposits of the
southwestern Colorado Plateau region.
Seventeen participants represented uranium
mining and exploration companies,
and many of them brought experiences
from various uranium districts
around the world.
The course began in the Laguna-
Jackpile mine area west of Albuquerque,
New Mexico, where an initial review of
Mesozoic stratigraphy described uranium
occurrences in the Jurassic age
Jackpile Sandstone, which make up the
stratigraphically highest uranium
deposits of importance in this part of
the Colorado Plateau. This was followed
the next day by a review of deposits in
the prolific Ambrosia Lake area, where
Joe Lister of Rio Grande Resources provided
historical, geologic, and production
background information of the
high-grade but currently inactive
Mount Taylor mine; outcrops of the
major Jurassic age host rocks were also
examined, with emphasis on the
Morrison Formation and its members in
the Grants region. Geologist Josh Crook
William X. Chávez, Jr. (SEG 1990 F), and Erich U. Petersen (SEG 1986 F)
Uranium field trip participants pose for a group photo.
of Neutron Energy Inc. provided details
on the historical production in
Ambrosia Lake.
Traveling to the famous Big Indian-
Lisbon Valley area of southeastern
Utah, our group was treated to an
underground visit—and lunch—at
Denison Mines Pandora mine near La
Sal. Jim Fisher of Denison Mines organized
this part of our course, and made
sure that our visit to the La Sal area was
productive and enjoyable. The visit
allowed participants to observe the
nature of stream channel systems and
the significance of organic matter as a
reductant in these sandstone-hosted
deposits. Besides getting a first-hand
look at exposures of the Salt Wash
Member of the Morrison Formation, we
also discussed the geochemistry of uranium
and vanadium, and the variability
of V/U ratios in these ore deposits of
the Colorado Plateau. A follow-up visit
to the historic Big Buck mine along
Steen Road—named after Charles Steen,
an unlikely pioneer in uranium exploration
and discovery in the Moab
area—gave participants the chance to
observe the stark contrasts between oxidized
and reduced zones within the
Triassic age Chinle Formation.
Anthony (Tony) Adkins, of Nucla,
Colorado, provided an excellent series
of mine and former mine stops the following
day, as we visited the Lisbon
mine of Constellation Copper Corpora -
tion, followed by stops at key outcrops
and former mine sites in the Utah-
Colorado border region east and southeast
of Lisbon Valley, ending at the
Burro mine near Slickrock, Colorado.
The mine visits offered the chance to
not only see the various styles of copper
and uranium mineralization in sandstones
of Cretaceous (Lisbon mine) and
Jurassic ages, but the opportunity to
discuss the complex geochemistry of
uranium and vanadium in terms of
transport, precipitation, and redox
considerations.
Our final day was spent traveling
from eastern Utah to Keystone, with
stops at outcrops and overlooks characterizing
the Jurassic stratigraphic section
of western Colorado; David Levy of Tetra
Tech provided an animated discussion
of the Uravan uranium reclamation site
and the issues associated with former
uranium mining and milling sites.
We acknowledge the essential support
of the various mines visited and the
mine staff that accommodated our re -
quests for mine visits. Darline Daley of
Quality Business Services was in charge
of course registration; her support was
critical in getting this field course up
and running. Darline, we are grateful
to you for making our task as course
organizers so much easier! Finally, the
course leaders are grateful for the discussions
provided by the attendees and
for their active participation in this
course, whether at outcrops or at dinner-table
sessions—their experience and
enthusiasm for uranium exploration
made for a memorable field course.
Because of the demand for this
U2009 offering, a reprise will be offered
in October of this year as a part of the
annual Geological Society of America
meeting; the course will start and end in
Albuquerque, New Mexico. 1
SEG NEWS