Taos Plateau volcanic field

Taos Plateau volcanic field
Daniel Schwen · CC BY-SA 4.0 · source
Name	Taos Plateau volcanic field
Photo caption	Basaltic lava flow near Questa, New Mexico
Location	Taos County, New Mexico, United States
Type	Volcanic field
Age	Pliocene–Pleistocene
Last eruption	~25,000–1.5 Ma (varies by source)

Taos Plateau volcanic field is a broad Pliocene–Pleistocene volcanic province located in northern New Mexico within Taos County, New Mexico and adjacent to the Rio Grande rift. The field contains widespread basalt and rhyolite volcanic centers, extensive lava flow plateaus, and multiple cinder cone clusters, and is proximal to communities such as Taos, New Mexico and Red River, New Mexico. Its volcanic record bears on regional magmatism associated with the Rio Grande rift, the tectonic evolution of the Southern Rocky Mountains, and Quaternary landscape change in the American Southwest.

Geology

The field overlies Tertiary and older strata of the San Juan Basin, the Raton Basin, and uplifted Precambrian rocks of the Proterozoic Sangre de Cristo Mountains. Bedrock beneath includes Tertiary volcanic rocks and Paleozoic sedimentary units mapped by the United States Geological Survey. Regional structural elements include the Rio Grande rift graben-bounding normal faults, the Taos Plateau uplift, and intersecting fault systems such as the Embudo fault zone and the Red River fault. Stratigraphic relations show emplacement of multi-stage volcanism from ~9 Ma to <1 Ma, preserved as shield volcanoes, stratocones, and tholeiitic flows that rest on older Santa Fe Group sediments and Precambrian basement.

Volcanic Features and Landforms

Prominent landforms include the Cerros del Rio basaltic plateau, the Latir volcanic field rhyolitic domes, and numerous maar and cinder cone clusters near Costilla County, Colorado and Taos County, New Mexico. Features observable are ʻaʻā and pāhoehoe flow textures, columnar jointing in thick flows, lava tubes, and scoria deposits around radial feeder dikes. The area contains isolated stratovolcanic remnants, shield volcanoes, and intrusions such as sills and dikes that feed lava domes and pyroclastic deposits. Glacial and fluvial modification by the Rio Grande and tributaries has sculpted basalt mesas, terraces, and escarpments adjacent to the Sangre de Cristo Mountains.

Eruption History and Chronology

Radiometric dating using K–Ar dating and 40Ar/39Ar dating techniques constrains major eruptive phases from roughly 9 million to less than 1 million years ago, with some late Pleistocene basaltic activity. Key eruptive centers show ages clustering in the late Miocene to Pliocene followed by renewed activity during the Pleistocene concurrent with extension in the Rio Grande rift. Paleomagnetic studies and tephrochronology correlate flows with regional volcanic units mapped by the New Mexico Bureau of Geology and Mineral Resources. Tephra layers correlate with Yellowstone hotspot migration debates and with magmatic pulses recorded in the Jemez volcanic field and San Juan volcanic field.

Petrology and Geochemistry

Lavas range from olivine tholeiite basalts to high-silica rhyolites, with intermediate andesite and dacite compositions recorded at discrete vents. Major- and trace-element geochemistry shows enrichment in incompatible elements and variable isotopic signatures (Sr–Nd–Pb) indicating contributions from lithospheric mantle, subcontinental mantle domains, and crustal assimilation of Precambrian basement. Mineral assemblages include olivine, clinopyroxene, plagioclase, orthopyroxene, and phenocrystic sanidine in rhyolites. Geochemical zoning within flows and paired basalt–rhyolite associations have been interpreted as evidence for fractional crystallization, magma mixing, and crustal melting processes similar to models applied to the Jemez Mountains and Latir volcanic field.

Tectonic Setting and Origins

The volcanic field developed in the northeastern sector of the Rio Grande rift, where lithospheric extension thins the mantle lithosphere and promotes decompression melting. Regional stress fields related to the uplift of the Colorado Plateau and subsidence of the Rio Grande depression influenced localization of magma ascent along normal faults and transfer zones such as the Red River Fault. Some researchers invoke interaction with far-field processes including the passage of the Farallon Plate remnants, mantle upwelling, and edge-driven convection to explain mantle heterogeneity. Comparative studies link magmatism here to contemporaneous activity in the San Juan Mountains and Taos volcanic region of the southern Rockies.

Ecology and Land Use

Vegetation across the plateau varies from pinyon–juniper woodlands and sagebrush steppe on basaltic soils to montane conifer forests on higher rhyolitic uplands, supporting wildlife typical of the Southern Rockies such as elk, black bear, and migratory bird species monitored by the U.S. Fish and Wildlife Service. Soils derived from volcanic parent material affect local agriculture and grazing patterns on private and public lands, including allotments managed by the Bureau of Land Management and grazing permits overseen by the United States Forest Service on adjacent national forest lands. Cultural landscapes include historical sites of Taos Pueblo and Hispanic land grants impacted by volcanic topography.

Recreation and Conservation

The region offers recreational attractions near Taos Ski Valley, Carson National Forest, and Rio Grande del Norte National Monument, including hiking, rock climbing, birding, and interpretive geology trails. Conservation efforts involve collaboration among the New Mexico Department of Game and Fish, National Park Service, and local land trusts to balance recreation, wildlife habitat protection, and cultural resource preservation. Designations such as state parks, wilderness areas, and municipal open-space initiatives aim to protect volcanic landforms, riparian corridors of the Rio Grande, and archeological sites associated with Pueblo and Hispanic heritage.

Category:Volcanic fields of New Mexico Category:Geology of Taos County, New Mexico