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At least 55 records · Page 3Linked to original sources
USGS1982

Shallow subsurface temperatures and some estimates of heat flow from the Colorado Plateau of northeastern Arizona

Temperature data to depths of a few hundred meters were obtained from 29 wells in northeastern Arizona; 12 in the region surrounding the San Francisco Volcanic Field, 8 in the Black Mesa area, and 9 in the south-central Colorado Plateau which includes the White Mountains. Although there was evidence for local hydrologic disturbances in many temperature profiles, most wells provided an estimate of the conductive thermal gradient at the site. A few thermal conductivities were measured and were combined with published regional averages for the north-central part of the Colorado Plateau to produce crude estimates of regional heat flux. None of the wells was accessible below the regional aquifers. To these depths, heat flow in the area of the San Francisco Volcanic Field appears to be controlled primarily by regional lateral water movement having a significant downward vertical component of velocity. The mean heat flow of 27?5 mW^-2 is only a third to a quarter of what we would expect in this tectonic setting. The heat that is being carried laterally and downward probably is being discharged at low enthalpy and low elevation in springs and streams of the Colorado Plateau and Mogollon Rim. In the vicinity of Black Mesa, heat-flow averages about 60 mW^-2, characteristic of the 'cool interior' of the Colorado Plateau. North of the White Mountain Volcanic Field, the average heat flow is about 95 mW^-2.

Open-File Report↗
USGS1999

Proceedings of the fourth biennial conference of research on the Colorado Plateau

The 13 chapters in this book were selected from the 75 research papers presented at the Fourth Biennial Conference of Research on the Colorado Plateau. The theme of this meeting centered around research, inventory, and monitoring on lands over the Colorado Plateau, with a focus on the newly created BLM Grand Staircase-Escalante National Monument. The conference, held on 15-18 September 1997 in Flagstaff, Arizona, was hosted by the USGS Forest and Rangeland Ecosystem Science Center Colorado Plateau Field Station (CPFS) and Northern Arizona University.

Colorado↗
USGS2026

Toward a four-dimensional petrogenetic model of a distributed volcanic field on the southern edge of the Colorado Plateau

A detailed characterization of the >3,000 square kilometer (km 2 ) Springerville volcanic field, located on the southern tip of the Colorado Plateau in Arizona, United States, with its more than 501 volcanic units and widely distributed >420 cinder cones and lava flows, provides constraints toward an integrated petrogenetic model for the field. Large-volume effusive tholeiitic eruptions at 2–1.5 mega-annum (Ma) transitioned to more numerous, smaller volume alkali olivine basalt (AOB) events at 1.5–1.0 Ma, with increasing abundances of evolved alkalic rocks (EARs), and a final 1.0–0.3 Ma period dominated by smaller volume, more explosive alkalic eruptions. Early large-scale melting in a relatively enriched lithospheric mantle (EM) source generated large-volume effusive tholeiitic magmas. Depths of tholeiite magma generation average about 90 kilometers (km) across the field, but depths for individual units decreased southward, consistent with lithospheric thinning toward the Colorado Plateau margin. Early and middle-stage transitional basalts, alkali olivine basalts (AOBs), and basanites originate from a progressively deeper (>100 km) region in a prevalent mantle (PREMA)-like asthenospheric source produced by increasingly smaller degrees of melting, as low as about 2 percent. The chemical signature of the basanites is consistent with small degrees of melting in a carbonated, asthenospheric source to depths of about 140 km. As heat waned, the last phase of volcanism was dominated by more explosive EARs derived at shallower lithospheric pressures but that have isotopic and trace element similarities to the deeper asthenospheric magmas. This suggests mixing between deeper basanitic and shallower tholeiitic magmas. With waning heat, eruptions became more localized along alignments, likely related to boundaries between blocks of Proterozoic crust with differing properties that affected magma ascent. The petrogenetic patterns are consistent with a variety of processes. Basin and Range Province extension, melting, and heat-induced weakening progressively eroded the Colorado Plateau’s thicker lithosphere, giving rise to relatively high degrees of partial melting from shallower (<90 km) sources that produced the early large volumes of effusive tholeiitic magma. Possible lithosphere delamination and removal, and a resulting steep boundary step with the asthenosphere, may have given rise to mantle edge convection, resulting in the mixing of basanitic and tholeiitic magmas. With plate motion, shear-driven upwelling likely gave an eastward component to convection, affecting relative amounts of melting at the field’s western boundary and corresponding with volcanism moving eastward during times of peak vent production by eruption of alkalic lavas, giving rise to more explosive and lower volume eruptions.

Arizona, New Mexico↗
USGS1989

Paleomagnetism and tectonic rotation of the lower Miocene Peach Springs Tuff: Colorado Plateau, Arizona, to Barstow, California

We have determined remanent magnetization directions of the lower Miocene Peach Springs Tuff at 41 localities in western Arizona and southeastern California. An unusual northeast and shallow magnetization direction confirms the proposed geologic correlation of isolated outcrops of the tuff from the Colorado Plateau to Barstow, California, a distance of 350 km. The Peach Springs Tuff was apparently emplaced as a single cooling unit about 18 or 19 Ma and is now exposed in 4 tectonic provinces west of the Plateau, including the Transition Zone, Basin and Range, Colorado River extensional corridor, and central Mojave Desert strike-slip zone. As such, the tuff is an ideal stratigraphic and structural marker for paleomagnetic assessment of regional variations in tectonic rotations about vertical axes. From 4 sites on the stable Colorado Plateau, we have determined a reference direction of remanent magnetization (I = 36.4°, D = 33.0°, α 95 = 3.4°) that we interpret as a representation of the ambient magnetic field at the time of eruption. A steeper direction of magnetization (I = 54.8°, D = 22.5°, α 95 = 2.3°) was observed at Kingman where the tuff is more than 100 m thick, and similar directions were determined at 7 other thick exposures of the Peach Springs Tuff. The steeper component is presumably a later-stage magnetization acquired after prolonged cooling of the ignimbrite. When compared to the Plateau reference direction, tilt-corrected directions from 3 of 6 sites in the central Mojave strike-slip zone show localized rotations up to 13° in the vicinity of strike-slip faults. The other three sites show no significant rotations with respect to the Colorado Plateau. Both clockwise and counterclockwise rotations were measured, and no systematic regional pattern is evident. Our results do not support kinematic models which require consistent rotation of large regions to accommodate the cumulative displacement of major post-middle Miocene strike-slip faults in the central Mojave Desert. Most of our sites in the Transition Zone and Basin and Range province have had no significant rotation, although small counterclockwise rotation in the McCullough and New York Mountains may be related to sinistral shear along en echelon faults southwest of the Lake Mead shear zone. The larger rotations occur in the Colorado River extensional corridor, where 8 of 14 sites show rotations ranging from 37° clockwise to 51° counterclockwise. These rotations occur in allochthonous tilt blocks which have been transported northeastward above the Chemehuevi-Whipple Mountains detachment fault. Upper-plate blocks within 1 km of the exposed detachment unexpectedly show no significant rotation. From this relation, we infer that rotations are accommodated along numerous low-angle faults at higher structural levels above the detachment surface.

Arizona, California↗
USGS1997

Proceedings of the third biennial conference of research on the Colorado Plateau

The papers in this volume are contributions from federal, state, and private sector researchers, who have come together to share scientific information with land managers on the Colorado Plateau. This Proceedings is the third in a series of publications that focuses on providing information to land managers on baseline scientific information pertaining to physical, cultural and biological resources of the Colorado Plateau. Support for these studies came from a spectrum of federal, state, and private partners concerned about the well-being of the Plateau's resources. I applaud the effort of the contributors. With modest funding and a broad base of public and institutional support, these authors have pursued important lines of work in the four states that comprise the Colorado Plateau biogeographic region.

Arizona, Colorado, New Mexico, Utah↗
USGS2023

Establishing big sagebrush seedlings on the Colorado Plateau

Factors such as soil type and precipitation vary across rangeland landscapes, and these factors affect restoration outcomes and ultimately mean that “one size fits all” management strategies are not effective across large, complex landscapes. Big sagebrush (Artemisia tridentata) is a foundational rangeland species that is important to wildlife habitat across the western U.S. On the Colorado Plateau, sagebrush is important browse for ungulates, such as mule deer and pronghorn, which motivates a great deal of restoration effort. However, most scientific knowledge of big sagebrush comes from the Great Basin, and we know much less about how to restore sagebrush on the Colorado Plateau, where soils and precipitation patterns are different and conditions are warmer and drier. This fact sheet describes research about establishing and restoring sagebrush seedlings on the Colorado Plateau.

Utah↗
USGS1970

Similarities, differences, and some genetic problems of the Wyoming and Colorado plateau types of uranium deposits in sandstone

Uranium deposits of the Wyoming roll type and the Colorado Plateau peneconcordant type are the principal domestic resources of uranium. Both types occur in lenticular sandstone beds of continental origin, have a similar suite of elements and minerals, are associated with mildly altered rock, and are thought to have formed by reduction precipitation from ground waters before significant regional deformation. They differ in several respects. The Wyoming deposits are in unlithified sandstone that is highly arkosic, whereas the Colorado Plateau deposits are in lithified sandstone that is only slightly to moderately arkosic. Uranium is the only ore metal in the Wyoming deposits, whereas vanadium or copper is more abundant than uranium in some of the Plateau deposits. The Wyoming deposits are elongate crescent-shaped bodies that extend vertically through, or partly through, a sandstone unit and which are scattered, like widely spaced beads on a string, along miles-long interfaces between oxidized (altered) and unoxidized sandstone, whereas the Plateau deposits are thin tabular layers that are nearly concordant to bedding and which occur as discrete bodies, like raisins in raisin bread, enveloped in rock altered by reduction. The Wyoming ore rolls and interfaces were dynamic, having been pushed downdip by downward-moving oxygen-bearing water that passed through the interfaces and deposited the ore minerals on the reducing side, whereas the Plateau deposits seemingly formed as static bodies, localized by intensive reducing "patches" in a mildly reducing environment. These differences focus attention on genetic problems relating to the Eh of the ore-bearing and altering solutions, the shape and localization of deposits, and the source of the uranium.

Arizona, Colorado, New Mexico, South Dakota, Utah,↗
USGS1956

Behavior of Colorado Plateau uranium minerals during oxidation

Uranium occurs as U(VI) and U(IV) in minerals of the Colorado Plateau ores. The number of species containing U(VI) is large, but only two U(IV) minerals are known from the Plateau: uraninite, and oxide, and coffinite, a hydroxy-silicate. These oxidize to yield U(VI) before reacting significantly with other mineral constituents. Crystal-structure analysis has shown that U(VI) invariable occurs as uranyl ion, UO 2 +2 . Uranyl ion may form complex carbonate or sulfate ions with resulting soluble compounds, but only in the absence of quinquevalent vanadium, arsenic, or phosphorous. In the presence of these elements in the +5 valence state, the uranyl ion is fixed in insoluble layer compounds formed by union of uranyl ion with orthovanadate, orthophosphate, or orthoarsenate. Under favorable conditions UO 2 +2 may react to form the relatively insoluble rutherfordine, UO 2 CO 3 , or hydrated uranyl hydroxides. These are rarely found on the Colorado Plateau as opposed to their excellent development in other uraniferous areas, a condition which is apparently related to the semiarid climate and low water table of the Plateau. Uranium may also be fixed as uranyl silicate, but little is known about minerals of this kind. In the present study emphasis has been placed on a detailing of the chemical and crystal structural changes which occur in the oxidation paragenetic sequence.

Utah↗
USGS2010

The Colorado Plateau IV: shaping conservation through science and management

Roughly centered on the Four Corners region of the southwestern United States, the Colorado Plateau covers some 130,000 square miles of sparsely vegetated plateaus, mesas, canyons, arches, and cliffs in Arizona, Utah, Colorado, and New Mexico. With elevations ranging from 3,000 to 14,000 feet, the natural systems found within the plateau are dramatically varied, from desert to alpine conditions. This book focuses on the integration of science and resource management issues in this unique and highly varied environment. Broken into three subsections, this volume addresses conservation biology, biophysical resources, and inventory and monitoring concerns. The chapters range in content, addressing conservation issues&ndash;past, present, and future&ndash;on the Colorado Plateau, measurement of human impacts on resources, grazing and wildland-urban interfaces, and tools and methods for monitoring habitats and species. An informative read for people interested in the conservation and natural history of the region, the book will also serve as a valuable reference for those people engaged in the management of cultural and biological resources of the Colorado Plateau, as well as scientists interested in methods and tools for land and resource management throughout the West.

Utah;Colorado;Arizona;New Mexico↗
USGS1993

Proceedings of the first biennial conference of research in Colorado Plateau National Parks

The 19 papers in this volume were selected from the 46 presentations given at the First Biennial Conference on Research in Colorado Plateau National Parks. The overall theme for this meeting was research, inventory, and monitoring in National Park Service units on the Colorado Plateau. The conference, held in Flagstaff Arizona, on 22-25 July 1991, was sponsored by the National Park Service Cooperative Park Studies Unit, Northern Arizona University, and the Petrified Forest, Zion, and Grand Canyon natural history associations.

Utah;Colorado;Arizona;New Mexico↗
USGS1966

Water from bedrock in the Colorado Plateau of Utah

The bedrock aquifers in the Colorado Plateau of Utah supply water that ranges widely in chemical quality and yield. The range of dissolved solids in 649 samples collected from 534 wells, springs, and water-yielding mine tunnels was from less than 100 to more than 390.000 ppm (parts per million). The yield of wells ranged from less than 1 to 54,000 barrels of water per day (less than 1 to 1,600 gallons per minute); whereas the yield of springs ranged from less than 1 to 4,100,000 barrels of water per day (less than 1 to 121,000 gallons per minute).

Utah↗
USGS1992

Organic matter diagenesis as the key to a unifying theory for the genesis of tabular uranium-vanadium deposits in the Morrison Formation, Colorado Plateau

Interstitial, epigenetic amorphous organic matter is intimately associated with uranium in the Grants uranium region on the southern part of the Colorado Plateau in northwestern New Mexico and is considered essential to genetic models for these deposits. In contrast, uranium minerals are intimately associated with authigenic vanadium chlorite and vanadium oxides in amorphous organic matter-poor ores of the Slick Rock and Henry Mountains mining districts on the northern part of the plateau, and therefore, in some genetic models amorphous organic matter is not considered crucial to the formation of these deposits. Differences in organic matter content can be explained by recognizing that amorphous organic matter-poor deposits have been subjected to more advanced stages of diagenesis than amorphous organic matter-rich deposits, during which organic compounds were broken down, solubilized, and removed during various diagenetic stages (e.g., sulfate reduction, methanogenesis, and organic acid production). Most diagenetic alterations (e.g., dissolution of framework grains and cements and precipitation of coarse-grained coffinite, vanadium clays, and vanadium oxides) characteristic of amorphous organic matter-poor deposits occurred when temperatures exceeded 80 degrees C--a temperature typical of the organic acid stage of diagenesis.Two factors combined to assure that a high percentage of the amorphous organic matter was removed from the Morrison Formation during diagenesis: the fact that the organic matter was humic (and therefore highly oxygenated), and that the juxtaposition of authigenic smectite and amorphous organic matter on grain rims facilitated clay mineral-organic catalysis reactions leading to the breakdown of large organic molecules into smaller, soluble molecules.Evidence that amorphous organic matter was involved in the genesis of organic matter-poor, as well as organic matter-rich, deposits includes the presence of leached iron-titanium oxides and strongly etched garnets (both attributed to leaching by organic acids), the gradation from organic matter-rich to organic matter-poor deposits in the Grants uranium region, the inverse correlation between the amount of amorphous organic matter and the intensity of diagenetic alteration, the ubiquitous occurrence of amorphous organic matter inclusions in coffinite, and the similarity in geometry of tabular uranium-vanadium ores and Holocene humate deposits. By recognizing that amorphous organic matter was crucial to the initial concentration of uranium (even in those deposits that presently contain little amorphous organic matter) and by recognizing the effects of the various stages of diagenesis on the ore, one genetic model may be applied to all of the sandstone-hosted, tabular-type uranium-vanadium deposits in the Morrison Formation on the Colorado Plateau.

Economic Geology↗
USGS2020

Genetically-informed seed transfer zones for Cleome lutea and Machaeranthera canescens across the Colorado Plateau and adjacent regions

Genetically-based seed transfer zones are described herein for two priority restoration species on and adjacent to the Colorado Plateau (Massatti 2020). Species include Cleome lutea Hook. (Capparaceae; commonly called yellow spiderflower or yellow beeplant; synonym Peritoma lutea (Hook.) Raf.) and Machaeranthera canescens (Pursh) A. Gray (Asteraceae; commonly called hoary tansyaster; synonym Dieteria canescens (Pursh) Nutt.). The seed transfer zones depict both evolutionary lineages and inferences of adaptation as discerned from molecular investigations. These shapefile data may support successful restoration outcomes if, for example, seed transfer follows seed transfer zones depicted herein and/or composite seed strategies for native plant materials development utilize seed transfer zones when determining which seed accessions may be combined. The ultimate goal of these seed transfer zones is to protect species’ natural patterns of genetic variation – genetic diversity is increasingly recognized a unit of conservation concern (Hoban et al. 2013) – and to understand species' adaptations to regional environmental gradients. Development of these seed transfer zones was funded by CPNPP, which was established, in part, to evaluate and develop native plant materials for important grass and forb species adapted to the unique ecological conditions of the Colorado Plateau (Wood et al. 2015). Each species’ shapefile data available in Massatti (2020) are described in turn.

Arizona, Colorado, New Mexico, Utah↗
USGS2023

Restoration research actions to address rapid change in drylands: Insights from the Colorado Plateau

The rapid intensification of ecological extremes in response to climate change and human land use is perhaps nowhere more apparent than in drylands, including the semiarid region of the Colorado Plateau in the southwestern United States. Here, we describe research directions to aid in the restoration of Colorado Plateau ecosystems during the UN Decade on Ecosystem Restoration (2021–2030) that 1) address high levels of heterogeneity 2) explore simultaneous global change drivers 3) are co-produced with a broad range of partners and 4) center Indigenous ways of knowing. We highlight restoration research efforts led by early career scientists grappling with informing management actions in a region where a rapidly changing climate intersects with historic grazing and continued land use pressures to create novel ecological extremes. We highlight restoration research efforts led by early career researchers grappling with informing management actions in a region where novel ecological extremes are the result of historic grazing, continued land-use pressures, and a rapidly changing climate.

Arizona, Colorado, New Mexico, Utah↗
USGS2012

Avian community responses to vegetation structure within chained and hand-cut pinyon-juniper woodlands on the Colorado Plateau

We investigated relationships between breeding birds and vegetation characteristics in fuels-reduction treatment areas within pinyon-juniper woodlands at locations over the Colorado Plateau. The goal of this study was to document differences in avian community responses to two types of pinyon-juniper fuels-reduction treatments (chained vs. hand-cut), relative to control sites. We selected 73 vegetation plots in southern Utah and northern Arizona, of which 33 had been previously thinned by handcutting or chaining, and 40 control plots in untreated pinyon-juniper woodlands. At the 73 locations we documented vegetation structure and counted birds within 3.1 ha circular plots during the 2005 and 2006 breeding seasons. We focused in particular on the effects of fuels-reduction treatments to 16 bird species that are considered pinyon-juniper obligates. We found that density of pinyon pines was the most important variable in predicting bird species richness in all treatments and at control sites. Abundance of Brewer&rsquo;s Sparrow (<i>Spizella breweri</i>) was negatively related to chained, but positively related to hand cut areas. Vesper Sparrow (<i>Poocetes graminius</i>) abundance was negatively related to both chaining and handcutting. Within 16 pinyon-juniper obligate bird species, abundance of five was positively related to pinyon-pine density, while two were positively related to juniper density. These responses, along with other bird-vegetation relationships influenced by treatment type, need to be considered by land managers when planning fuels reduction treatments in pinyon-juniper woodland habitat in the Colorado Plateau.

Arizona, Colorado, New Mexico, Utah↗
USGS1991

Middle to late Cenozoic magmatism of the southeastern Colorado Plateau and central Rio Grande rift (New Mexico and Arizona, U.S.A.): A model for continental rifting

The region of the present Rio Grande rift and southeastern Colorado Plateau underwent lithospheric extension during middle to late Cenozoic deformation affecting the entire southwestern U.S. Lithospheric mantle was disrupted, and in many regions displaced or replaced by asthenospheric mantle at depths from which basaltic magmas were derived and erupted to the surface. Study of the igneous rocks erupted or intruded during this deformation yields insights into processes of magmatism associated with extension of continental lithosphere. Magmatic rocks associated with an early (late Oligocene-early Miocene) ductile phase of extension are dominantly basaltic andesites and related, calc-alkaline intermediate to silicic derivative rocks. Mafic magmas were probably derived from isotopically “enriched” lithospheric mantle. Igneous rocks associated with a later (middle Miocene-Holocene), more brittle phase of extension include widespread basaltic rocks and localized central volcanoes of intermediate to silicic composition. Isotopic compositions of mafic rocks, which include both tholeiitic and alkalic basalts, correlate strongly with tectonic setting and lithospheric structure. Basalts erupted in areas of greatest crustal extension, such as the central and southern rift and Basin and Range province, were derived from isotopically “depleted” (correlated with “asthenospheric”) mantle. Also, isotopic compositions of Pliocene to Holocene basalts are slightly more depleted than those of Miocene basalts, suggesting that subcrustal lithospheric mantle was thinned during late Miocene extension. Intermediate rocks of the central volcanoes formed by a complex combination of processes, probably dominated by fractional crystallization and by assimilation of upper and lower crust in isolated, small magma chambers. The petrologic, geochemical, and isotopic data are compatible with a model, derived first from geophysical data, whereby lithosphere is thinned beneath the central rift and southeastern Colorado Plateau, with greatest thinning centered beneath the axis of the rift. A lithospheric model involving uniform-sense simple shear does not appear compatible with the data as presently understood.

Arizona, New Mexico↗
USGS2020

Sand dunes, modern and ancient, on southern Colorado Plateau tribal lands, southwestern USA

A mantle of both active and stable aeolian sand covers approximately 34,000 km 2 of northern Arizona, western New Mexico and southern Utah on the southern Colorado Plateau. From west to east, these deposits can be subdivided into the Kaibab-Moenkopi dunes, Chinle Valley dunes, and Chaco dunes, all of which include relict, partly stable and mobile aeolian sand. Locally, these deposits have distinct compositional characteristics. An examination of previous studies into disparate aspects of Colorado Plateau dunes, taken in the context of local geology, Quaternary landscape history and geomorphic processes, provides new insights into interpretation of this regional aeolian sedimentary record. Additional new data about the characteristics of the deposits, and an assessment of present-day climatic conditions enhances our ability to interpret the relative influences of ecosystem and geomorphologic processes with climate variability that continue to influence both new dune formation and reactivation of older deposits. Taken as a whole, the data emphasizes the role that local landscape conditions and history play in providing the context for correctly interpreting aeolian activity and depositional environments, and whether sediment supply or climate play a dominant role in sand dune formation. This is particularly true in the Little Colorado River Valley of northeastern Arizona, where Quaternary volcanic activity has significantly influenced the local landscape processes, deposit characteristics, and dune paleohistory.

Book chapter↗