2
southwestern New Mexico and southeastern Arizona in
southwestern United States and northern Mexico (Dicken
et al., 2022). In New Mexico these belts are found in the
southwestern part of the state (Figure 1). New 40Ar/39Ar
geochronology coupled with previous age determinations
has constrained these deposits into three pulses of ore pro-
ducing magmatism: (1) ~78–71 Ma (Laramide pulse 1),
(2) ~59–50 Ma (Laramide pulse 2) and (3) ~40–30 Ma
(Paleogene pulse). These deposits have the potential for
hosting various critical minerals, including Cu, Zn, Bi, Co,
Ni, rare earth elements (REE), Te, and W. New research
into understanding the geological and geochronological
characterization of these deposits and their critical minerals
endowment is vital for the future of exploration and mining
in New Mexico. With recent thesis work (Stafford, 2024)
undertaken on the geochronology and research of the criti-
cal minerals potential of selected Laramide porphyry Cu
deposits, new emphasis has now been placed on research-
ing the endowment and characterization of the Paleogene
Mo-W deposits in New Mexico. Figure 1 is a modified figure
from Stafford (2024), and shows the overlapping age ranges
of these selected deposits and that most of the Paleogene
Mo-W deposits (highlighted in green on the map) lie along
or south of the Texas Lineament. Hence more geochemical
characterization and further improved geochronology with
the use of 40Ar/39Ar dating is conducted in this study to
continue to resolve remaining uncertainties regarding these
trends.
METHODS
Sampling of new areas particularly within the White Signal,
Lordsburg, Carpenter and Eureka districts are planned to be
undertaken for further 40Ar/39Ar dating. This will involve
identifying precise sample locations, collecting three to four
surface samples (from outcrop, ground or waste piles etc)
for geochronology and geochemistry. Additionally with
their GPS coordinates and lithology and mineralogical
descriptions to be also included with each sample.
New ages for some districts were obtained using mod-
ern, high precision 40Ar/39Ar geochronology performed
at the New Mexico Geochronology Research Laboratory
(NMGRL). Samples of fresh, least altered intrusive rocks
were collected for geochronology, as well as for whole rock
and trace element geochemistry and thin section prepara-
tion. Currently more samples from the Black Hawk, Little
Hatchet Mountains, Steins Pass and Victorio districts are
undergoing geochronology assessment. Future samples after
further field work in southwestern New Mexico from other
districts are also planned to be dated and whilst undergoing
whole rock and trace element geochemistry and thin sec-
tion preparation.
Creating a targeting criterion for the critical minerals
potential will be one of the final steps of drawing together
all historic and current work completed around the gen-
esis, geochemistry and geochronology of the Laramide and
Paleogene deposits of southwestern New Mexico is the goal
of this study. Developing a thorough background research
and a disciplinary collaboration effort with researchers in
order to create a holistic exploration targeting scheme that
will enable future exploration projects to seek these deposits
out easier involves examining district, state, and regional
scale geological and geochemical trends of these deposits
(McCuaig and Hronsky, 2014) and the cooperation of the
several geological surveys in California, Arizona, and Texas.
Thus, this explorative evaluation of the select Laramide and
Paleogene deposits will assist in the creation of a targeting
criteria which will be basis for future exploration for critical
minerals in southwestern U.S.
PRELIMINARY RESULTS
The results of previous 40 Ar/39Ar geochronology work on
some of the mining districts in southwestern New Mexico
and southeastern Arizona are shown in Table 1.
Figure 1. Laramide porphyry Cu (orange) and Paleogene
Mo-W belts (green) in southwestern New Mexico. Modified
from Stafford (2024) with updated ages
southwestern New Mexico and southeastern Arizona in
southwestern United States and northern Mexico (Dicken
et al., 2022). In New Mexico these belts are found in the
southwestern part of the state (Figure 1). New 40Ar/39Ar
geochronology coupled with previous age determinations
has constrained these deposits into three pulses of ore pro-
ducing magmatism: (1) ~78–71 Ma (Laramide pulse 1),
(2) ~59–50 Ma (Laramide pulse 2) and (3) ~40–30 Ma
(Paleogene pulse). These deposits have the potential for
hosting various critical minerals, including Cu, Zn, Bi, Co,
Ni, rare earth elements (REE), Te, and W. New research
into understanding the geological and geochronological
characterization of these deposits and their critical minerals
endowment is vital for the future of exploration and mining
in New Mexico. With recent thesis work (Stafford, 2024)
undertaken on the geochronology and research of the criti-
cal minerals potential of selected Laramide porphyry Cu
deposits, new emphasis has now been placed on research-
ing the endowment and characterization of the Paleogene
Mo-W deposits in New Mexico. Figure 1 is a modified figure
from Stafford (2024), and shows the overlapping age ranges
of these selected deposits and that most of the Paleogene
Mo-W deposits (highlighted in green on the map) lie along
or south of the Texas Lineament. Hence more geochemical
characterization and further improved geochronology with
the use of 40Ar/39Ar dating is conducted in this study to
continue to resolve remaining uncertainties regarding these
trends.
METHODS
Sampling of new areas particularly within the White Signal,
Lordsburg, Carpenter and Eureka districts are planned to be
undertaken for further 40Ar/39Ar dating. This will involve
identifying precise sample locations, collecting three to four
surface samples (from outcrop, ground or waste piles etc)
for geochronology and geochemistry. Additionally with
their GPS coordinates and lithology and mineralogical
descriptions to be also included with each sample.
New ages for some districts were obtained using mod-
ern, high precision 40Ar/39Ar geochronology performed
at the New Mexico Geochronology Research Laboratory
(NMGRL). Samples of fresh, least altered intrusive rocks
were collected for geochronology, as well as for whole rock
and trace element geochemistry and thin section prepara-
tion. Currently more samples from the Black Hawk, Little
Hatchet Mountains, Steins Pass and Victorio districts are
undergoing geochronology assessment. Future samples after
further field work in southwestern New Mexico from other
districts are also planned to be dated and whilst undergoing
whole rock and trace element geochemistry and thin sec-
tion preparation.
Creating a targeting criterion for the critical minerals
potential will be one of the final steps of drawing together
all historic and current work completed around the gen-
esis, geochemistry and geochronology of the Laramide and
Paleogene deposits of southwestern New Mexico is the goal
of this study. Developing a thorough background research
and a disciplinary collaboration effort with researchers in
order to create a holistic exploration targeting scheme that
will enable future exploration projects to seek these deposits
out easier involves examining district, state, and regional
scale geological and geochemical trends of these deposits
(McCuaig and Hronsky, 2014) and the cooperation of the
several geological surveys in California, Arizona, and Texas.
Thus, this explorative evaluation of the select Laramide and
Paleogene deposits will assist in the creation of a targeting
criteria which will be basis for future exploration for critical
minerals in southwestern U.S.
PRELIMINARY RESULTS
The results of previous 40 Ar/39Ar geochronology work on
some of the mining districts in southwestern New Mexico
and southeastern Arizona are shown in Table 1.
Figure 1. Laramide porphyry Cu (orange) and Paleogene
Mo-W belts (green) in southwestern New Mexico. Modified
from Stafford (2024) with updated ages