1
25-022
Critical Minerals in Laramide and Paleogene Porphyry,
Polymetallic Vein, and Skarn Deposits in Southern New Mexico
S.A. Moses
New Mexico Institute of Mining and Technology,
Socorro, NM
V.T. McLemore
New Mexico Bureau of Geology and Mineral
Resources/NM Tech, Socorro, NM
N.A. Iverson
New Mexico Bureau of Geology and Mineral
Resources/NM Tech, Socorro, NM
K.T. Stafford
Telesto Solutions Inc., Silver City, NM
I.C. Sanchez
New Mexico Institute of Mining and Technology,
Socorro, NM
A. Appah
New Mexico Institute of Mining and Technology,
Socorro, NM
E.J. Owen
New Mexico Bureau of Geology and Mineral
Resources/NM Tech, Socorro, NM
N. Hurtig
New Mexico Institute of Mining and Technology,
Socorro, NM
R. Otoo
New Mexico Institute of Mining and Technology,
Socorro, NM
ABSTRACT
New Mexico lies at the eastern edge of one of the world’s
great metal-bearing provinces hosting numerous Laramide
and Paleogene mineral deposits. Southwestern New Mexico
contains Laramide porphyry Cu (±Mo, Au) and Paleogene
Mo-W deposits. Porphyry deposits are generally large, low-
grade deposits containing Cu, Fe, Mo, Au sulfides (and
other metal sulfides) associated with porphyritic intru-
sions and exhibit characteristic alteration styles. Porphyry
deposits can also be spatially and temporally associated
with skarn deposits and polymetallic veins. All of these
deposits have the potential to host various critical minerals,
including Cu, Zn, Bi, Co, Ni, rare earth elements (REE),
Te, and W. Critical minerals may be found as substitutions
within ore minerals or as separate mineral phases. These
deposits are constrained using 40 Ar/39Ar dating into three
ore-producing magmatic pulses: 1) ~78–71 Ma Laramide
pulse, 2) ~59–50 Ma, Laramide pulse, and 3) ~40–30 Ma
Paleogene pulse. New and historic whole-rock geochemical
data have highlighted areas with critical minerals potential
that require further study.
INTRODUCTION AND GEOLOGICAL
BACKGROUND
Porphyry Cu deposits form through magmatic-hydrother-
mal processes above active subduction zones at convergent
plate margins and are associated with calc-alkaline batho-
liths and volcanic arcs (Sillitoe, 1972 2010 John and
Taylor, 2016). Porphyry Cu deposits can be spatially and
temporally associated with skarn deposits, polymetallic
veins, polymetallic replacement deposits, distal dissemi-
nated gold-silver deposits, epithermal vein (intermediate/
low sulfidation gold-silver) and high sulfidation epithermal
(gold, silver, copper, arsenic) deposits. Porphyry Cu depos-
its are the world’s most important source of copper, more
than 60% of the annual world Cu production and about
65% of known Cu resources (John et al., 2010). Porphyry
Cu deposits along with the other spatially associated depos-
its supply nearly ¾ of the world’s Cu, ½ the Mo, as much
as 1 ⁄5 of the Au, about 80% of the Re, most of Se and Te,
and minor amounts of Ag, Pd, Pt, Bi, Zn, and Pb (Sillitoe,
2010). An example of such systems includes the Southwest
Laramide Porphyry Belt and Middle Tertiary W skarns of
25-022
Critical Minerals in Laramide and Paleogene Porphyry,
Polymetallic Vein, and Skarn Deposits in Southern New Mexico
S.A. Moses
New Mexico Institute of Mining and Technology,
Socorro, NM
V.T. McLemore
New Mexico Bureau of Geology and Mineral
Resources/NM Tech, Socorro, NM
N.A. Iverson
New Mexico Bureau of Geology and Mineral
Resources/NM Tech, Socorro, NM
K.T. Stafford
Telesto Solutions Inc., Silver City, NM
I.C. Sanchez
New Mexico Institute of Mining and Technology,
Socorro, NM
A. Appah
New Mexico Institute of Mining and Technology,
Socorro, NM
E.J. Owen
New Mexico Bureau of Geology and Mineral
Resources/NM Tech, Socorro, NM
N. Hurtig
New Mexico Institute of Mining and Technology,
Socorro, NM
R. Otoo
New Mexico Institute of Mining and Technology,
Socorro, NM
ABSTRACT
New Mexico lies at the eastern edge of one of the world’s
great metal-bearing provinces hosting numerous Laramide
and Paleogene mineral deposits. Southwestern New Mexico
contains Laramide porphyry Cu (±Mo, Au) and Paleogene
Mo-W deposits. Porphyry deposits are generally large, low-
grade deposits containing Cu, Fe, Mo, Au sulfides (and
other metal sulfides) associated with porphyritic intru-
sions and exhibit characteristic alteration styles. Porphyry
deposits can also be spatially and temporally associated
with skarn deposits and polymetallic veins. All of these
deposits have the potential to host various critical minerals,
including Cu, Zn, Bi, Co, Ni, rare earth elements (REE),
Te, and W. Critical minerals may be found as substitutions
within ore minerals or as separate mineral phases. These
deposits are constrained using 40 Ar/39Ar dating into three
ore-producing magmatic pulses: 1) ~78–71 Ma Laramide
pulse, 2) ~59–50 Ma, Laramide pulse, and 3) ~40–30 Ma
Paleogene pulse. New and historic whole-rock geochemical
data have highlighted areas with critical minerals potential
that require further study.
INTRODUCTION AND GEOLOGICAL
BACKGROUND
Porphyry Cu deposits form through magmatic-hydrother-
mal processes above active subduction zones at convergent
plate margins and are associated with calc-alkaline batho-
liths and volcanic arcs (Sillitoe, 1972 2010 John and
Taylor, 2016). Porphyry Cu deposits can be spatially and
temporally associated with skarn deposits, polymetallic
veins, polymetallic replacement deposits, distal dissemi-
nated gold-silver deposits, epithermal vein (intermediate/
low sulfidation gold-silver) and high sulfidation epithermal
(gold, silver, copper, arsenic) deposits. Porphyry Cu depos-
its are the world’s most important source of copper, more
than 60% of the annual world Cu production and about
65% of known Cu resources (John et al., 2010). Porphyry
Cu deposits along with the other spatially associated depos-
its supply nearly ¾ of the world’s Cu, ½ the Mo, as much
as 1 ⁄5 of the Au, about 80% of the Re, most of Se and Te,
and minor amounts of Ag, Pd, Pt, Bi, Zn, and Pb (Sillitoe,
2010). An example of such systems includes the Southwest
Laramide Porphyry Belt and Middle Tertiary W skarns of