Mogollon-Datil volcanic field

Mogollon-Datil volcanic field
Name	Mogollon-Datil volcanic field
Location	Catron County, New Mexico, Socorro County, New Mexico, Grant County, New Mexico
Type	Volcanic field
Age	Oligocene–Miocene
Last eruption	~Miocene

Mogollon-Datil volcanic field is a large Oligocene to early Miocene volcanic province in southwestern New Mexico that records episodic silicic volcanism, caldera formation, and associated magmatism across the Basin and Range Province, Colorado Plateau, and adjacent provinces. The field preserves extensive ignimbrites and rhyolitic domes that document interactions among regional tectonics, subduction history along the western margin of North America, and mantle-crust processes linked to the evolution of the Farallon Plate and its remnants. Studies of the field have informed interpretations of caldera dynamics, mineralizing systems, and landscape evolution in the American Southwest.

Geology and Tectonic Setting

The volcanic field lies within the southern part of the Colorado Plateau margin and the northern extent of the Basin and Range Province, adjacent to the Rio Grande Rift and proximal to the Laramide orogeny-affected regions. Its emplacement followed changes in plate interactions involving the Farallon Plate, San Andreas Fault, and later Mendocino Triple Junction migrations, and contemporaneous with mantle upwelling linked to the Challis volcanic belt and the Yellowstone hotspot track. Regional deformation associated with the Sevier orogeny and post-orogenic collapse influenced crustal thickness and stress regimes that controlled magma generation and emplacement. The field overlays a basement comprised of Proterozoic terranes correlated with the Mazatzal Province, Yavapai Province, and remnants of the Transcontinental Proterozoic provinces.

Volcanic Units and Stratigraphy

Stratigraphic architecture includes an overlapping succession of ash-flow tuffs, lava flows, and hypabyssal intrusions, with named units such as the iconic ash-flow sheets correlated to caldera-forming eruptions alongside younger rhyolite domes. Successions interfinger with sedimentary cover sequences deposited in intercalated basins related to Santa Fe Group-type rift basins and synvolcanic fluvial systems that correlate with units recognized in the Animas Valley, Mimbres River drainage, and Gila River catchments. Stratigraphic correlations employ radiometric tying to regional marker horizons used across the San Juan Basin, Animas Mountain exposures, and the Bootheel region to reconcile lateral facies changes and pyroclastic dispersal patterns.

Chronology and Eruption History

High-precision dating using techniques calibrated against standards applied in studies of the Eocene-Oligocene transition and the Miocene Climatic Optimum has constrained major eruptive pulses to the late Oligocene through early Miocene, broadly spanning roughly 34–20 million years ago. Temporal clusters correspond to documented ignimbrite flare-ups synchronous with volcanic episodes in the Trans-Pecos volcanic field, San Juan volcanic field, and other southwestern provinces. Individual caldera-forming eruptions produced vast ignimbrite sheets that can be traced across paleodrainage systems to distal depositional basins, and tephrochronologic frameworks tie eruptive episodes to regional changes observed in Paleogene and Neogene sedimentary archives.

Petrology and Geochemistry

Rocks of the field are dominantly high-silica rhyolites and dacites, with accessory andesites and basaltic enclaves recording crustal assimilation and magma mixing processes comparable to petrogenetic models developed for the Sierra Madre Occidental and Central Volcanic Zone. Geochemical signatures include elevated incompatible element abundances and radiogenic isotope ratios that reflect contributions from mesozonal crustal sources similar to those characterized in Proterozoic basement terranes and younger mantle-derived inputs documented in studies of the Great Basin. Trace-element patterns and isotopic systematics (e.g., Sr, Nd, Pb) record degrees of partial melting, fractional crystallization, and crustal contamination analogous to processes invoked for the Ignimbrite flare-up phenomena elsewhere in western North America.

Structure and Caldera Complexes

The field contains multiple nested and overlapping caldera structures with complex ring-fracture systems, resurgent domes, and collapse-related faulting comparable to architectures described at Long Valley Caldera, Valles Caldera, and La Garita Caldera. Structural studies map caldera margins, intracaldera ignimbrite facies, and post-collapse intrusive bodies that exploit regional fault systems linked to the Rio Grande rift and northwest-striking transfer faults comparable to structures in the Laramide belt. Geophysical surveys and field mapping have delineated subsurface plutons, ring dike complexes, and feeder systems that inform models of magma chamber geometry developed for other major silicic provinces.

Mineralization and Economic Resources

Hydrothermal systems associated with the volcanic and intrusive history produced epithermal mineral deposits, skarn occurrences, and porphyry-style alteration zones that have been explored for precious and base metals similar to mineralization in the Valles mining district and the Santa Rita and Jerome districts. Known deposits include vein-hosted gold-silver occurrences, polymetallic sulfide mineralization, and skarn-related copper and tungsten mineralization tied to intrusive phases. These mineralizing episodes intersected with regional metallogenic belts recognized across Arizona, New Mexico, and the Mexican Volcanic Belt, and were influenced by structural permeability along caldera margins and ring faults.

Paleoclimate, Erosion, and Landscape Evolution

The post-volcanic history records climate-driven erosion, pedogenesis, and drainage integration that transformed pyroclastic topography into present-day mesas, badlands, and valley floors evident in landscapes similar to those in the Gila Wilderness, Gila Cliff Dwellings National Monument, and Apache-Sitgreaves National Forests. Fluvial incision tied to Pleistocene climatic oscillations, along with regional uplift related to Rio Grande rift evolution, controlled denudation rates and the exposure of intracaldera plutonic rocks analogous to patterns seen in the Colorado Plateau escarpments. Paleoenvironmental proxies preserved in interbedded lacustrine and fluvial sediments contribute to reconstructions of Oligocene–Miocene paleoclimate trends paralleling records from the Great Plains and Southwestern United States.

Category:Volcanic fields of New Mexico Category:Calderas of the United States