1
24-044
Geochronology and Critical Mineral Potential of Selected
Laramide Porphyry and Related Deposits in Southwest
New Mexico
K. T. Stafford
New Mexico Institute of Mining and Technology,
Socorro, NM
V. T. McLemore
New Mexico Bureau of Geology and Mineral
Resources, Socorro, NM
N. A. Iverson
New Mexico Bureau of Geology and Mineral
Resources, Socorro, NM
ABSTRACT
Southwestern New Mexico is part of a large belt of Late
Cretaceous to Eocene copper porphyry deposits found in
Arizona, New Mexico, and Mexico. These deposits are the
result of arc magmatism that occurred during the Laramide
orogeny. Recently, attention has been brought to other
commodities that can be extracted as by- and co-products,
many of which are critical minerals. A new compilation of
the geochronology of these deposits shows two main pulses
of magmatism that produced mineralized deposits and,
along with new dates by the author, shines new light on
the geologic history of these deposits and the role it plays in
critical mineral abundance.
INTRODUCTION
Copper porphyry deposits are some of the largest and most
well-known copper deposits found in the world. They pro-
duce three-quarters of the world’s copper supply, half of
the molybdenum, and a large portion of the gold [1]. In
addition to these primary commodities and co-products,
many significant by-products are also produced from these
deposits, which include Platinum Group Elements (PGEs),
Te, In, Ga, Ge, Re, and others. Many of these elements are
of increasing importance in the face of the coming green-
energy transition, have important defense and national
security uses, or are subject to supply chain issues due to the
reliance on imports. As such, the United States Geological
Survey has designated many of these commodities as criti-
cal minerals, while copper has been recently designated a
critical energy material by the Department of Energy. Due
to these reasons, copper porphyry systems have an increased
importance in the future of mining, and increasing the
domestic mining capability in the United States is critical.
Southwest New Mexico lies at the eastern end of the
southwest Laramide porphyry belt stretching from Arizona
into western New Mexico and northern Mexico (Figure 1).
These deposits are responsible for a large portion of domes-
tic copper production in the United States, and include
world-class deposits. These deposits are largely Laramide in
age, ranging from ~75–45 Ma [2][3]. While most of the
larger deposits are well-known in age, some of the smaller
deposits and prospects lack modern geochronology. This
is especially important as there is overlap of Laramide and
mid-Tertiary deposits in the same area, leading to some
confusion as to the age and nature of some deposits. Mid-
Tertiary deposits are the result of extensional tectonics, and
as a result are more alkaline and have different geochemi-
cal characteristics, mineralogy, and commodities than
Laramide deposits, which could have an effect on which
critical minerals could be present. New and improved
40 Ar/39Ar geochronology of various deposits in southwest
New Mexico has settled the debate on whether some dis-
tricts are Laramide or mid-Tertiary.
24-044
Geochronology and Critical Mineral Potential of Selected
Laramide Porphyry and Related Deposits in Southwest
New Mexico
K. T. Stafford
New Mexico Institute of Mining and Technology,
Socorro, NM
V. T. McLemore
New Mexico Bureau of Geology and Mineral
Resources, Socorro, NM
N. A. Iverson
New Mexico Bureau of Geology and Mineral
Resources, Socorro, NM
ABSTRACT
Southwestern New Mexico is part of a large belt of Late
Cretaceous to Eocene copper porphyry deposits found in
Arizona, New Mexico, and Mexico. These deposits are the
result of arc magmatism that occurred during the Laramide
orogeny. Recently, attention has been brought to other
commodities that can be extracted as by- and co-products,
many of which are critical minerals. A new compilation of
the geochronology of these deposits shows two main pulses
of magmatism that produced mineralized deposits and,
along with new dates by the author, shines new light on
the geologic history of these deposits and the role it plays in
critical mineral abundance.
INTRODUCTION
Copper porphyry deposits are some of the largest and most
well-known copper deposits found in the world. They pro-
duce three-quarters of the world’s copper supply, half of
the molybdenum, and a large portion of the gold [1]. In
addition to these primary commodities and co-products,
many significant by-products are also produced from these
deposits, which include Platinum Group Elements (PGEs),
Te, In, Ga, Ge, Re, and others. Many of these elements are
of increasing importance in the face of the coming green-
energy transition, have important defense and national
security uses, or are subject to supply chain issues due to the
reliance on imports. As such, the United States Geological
Survey has designated many of these commodities as criti-
cal minerals, while copper has been recently designated a
critical energy material by the Department of Energy. Due
to these reasons, copper porphyry systems have an increased
importance in the future of mining, and increasing the
domestic mining capability in the United States is critical.
Southwest New Mexico lies at the eastern end of the
southwest Laramide porphyry belt stretching from Arizona
into western New Mexico and northern Mexico (Figure 1).
These deposits are responsible for a large portion of domes-
tic copper production in the United States, and include
world-class deposits. These deposits are largely Laramide in
age, ranging from ~75–45 Ma [2][3]. While most of the
larger deposits are well-known in age, some of the smaller
deposits and prospects lack modern geochronology. This
is especially important as there is overlap of Laramide and
mid-Tertiary deposits in the same area, leading to some
confusion as to the age and nature of some deposits. Mid-
Tertiary deposits are the result of extensional tectonics, and
as a result are more alkaline and have different geochemi-
cal characteristics, mineralogy, and commodities than
Laramide deposits, which could have an effect on which
critical minerals could be present. New and improved
40 Ar/39Ar geochronology of various deposits in southwest
New Mexico has settled the debate on whether some dis-
tricts are Laramide or mid-Tertiary.