Navajo Aquifer Research Articles

Iron isotope evidence for siderite precursors to iron oxide concretions from the Navajo Sandstone, Utah (USA)

The discovery of spherical accumulations of iron oxide mineralization on Mars has prompted renewed interest in widespread but enigmatic accumulations of iron oxide on Earth. The rinded iron oxide concretions found in the Navajo Sandstone (Utah, USA) have been among the most extensively studied of these occurrences. At least four different models have been proposed for the formation of iron oxide concretions in the Navajo Sandstone. These include 1) mixing of reduced Fe(II)-bearing and oxygenated groundwaters, 2) neutralization of oxidized, acidic waters by calcite concretions, 3) neutralization of reduced, acidic waters by calcite concretions, and 4) oxidation of siderite by microbes during invasion of the Navajo aquifer by oxygenated groundwaters. We measured δ56Fe values of iron-bearing minerals from whole-rock Navajo Sandstone, concretionary iron oxide cements, iron oxide stains that are oriented in the direction of paleo-groundwater flow, iron oxide stains on the interior of rinded concretions, and ferroan carbonate cements. We have then combined these data with published measurements to evaluate each of the four published models. Whole rock Navajo Sandstone from the Kolob Plateau has been interpreted to be unaltered by bleaching fluids and has a δ56Fe value of 0.21‰. Iron in the Kolob Plateau sample comprises a mixture of hematite grain coatings (δ56Fe = 0.12‰) and a magnetic mineral fraction (interpreted to comprise largely detrital magnetite) that has a higher δ56Fe value (0.45‰). Iron oxide cements have δ56Fe values that are typically negative and as low as −0.74‰. In contrast, iron oxide-stained Navajo Sandstone in close proximity to a rinded iron oxide concretion has δ56Fe values that are 0.9 to 1‰ greater than the δ56Fe value of the associated iron oxide concretion. Finally, ferroan carbonates from the Navajo Sandstone yield δ56Fe values as low as −0.86‰. These values are in good agreement with measurements published previously for lithologies for which comparable measurements have been made. The presence of ferroan carbonates with negative δ56Fe values is evidence that aqueous Fe(II) was transported through the Navajo Sandstone aquifer and produced carbonate mineralization with negative δ56Fe values. The difference in δ56Fe values between the iron oxide concretions and associated iron oxide staining is more consistent with equilibrium fractionation between aqueous Fe(II) and Fe(II) adsorbed on quartz grains than it is with equilibrium fractionation between aqueous Fe(II) and any reduced or oxidized iron oxide mineral species. The negative δ56Fe values of the iron oxide concretions are best explained by oxidation of a reduced iron phase in a closed system from which no aqueous Fe(II) could escape. We interpret the iron isotope data as evidence that iron was stripped from Navajo sand grains by reducing fluids, reprecipitated in the Navajo aquifer as siderite, and oxidized by groundwaters under closed conditions during incision of the Colorado Plateau.

Hopi Film, the Indigenous Aesthetic and Environmental Justice: Victor Masayesva Jr.'sPaatuwaqatsi – Water, Land and Life

Since the early 1980s, the Hopi filmmaker and photographer Victor Masayesva Jr. has played an influential role in Native American multimedia production in the United States. This article examines Masayesva's filmPaatuwaqatsi: Water, Land and Life(2007), which documents a 1,650-mile run made by Hopis from their home villages in Northern Arizona to Mexico City in early 2006. The run marked the closure of the Mohave Generating Station in southern Nevada and the Black Mesa coal mine which fuelled the power plant. It also celebrated the shutting down of the controversial coal slurry pipeline between the plant and mine that required for its operation the pumping of 1.2 billion gallons of pristine water annually from the Navajo Aquifer, which lies under the homelands of the Hopi and Navajo nations. The article explains how Hopis' affective relationship with place is put into action through the acts of running, prayer and personal sacrifice. It reviews Masayesva’s filmmaking career to date and considers his core idea of the indigenous aesthetic, a set of principles that has guided the practical decisions and artistic choices he has made in the course of over thirty years' working as an independent media producer. After a close analysis of selected scenes inPaatuwaqatsi, the article concludes by noting, first, how the film negotiates internal divisions within Hopi society over development and environmental issues and, second, how it engages the impact of continuing drought and ongoing climate change on the American Southwest.

Alkali feldspar dissolution and secondary mineral precipitation in batch systems: 3. Saturation states of product minerals and reaction paths

In order to evaluate the complex interplay between dissolution and precipitation reaction kinetics, we examined the hypothesis of partial equilibria between secondary mineral products and aqueous solutions in feldspar–water systems. Speciation and solubility geochemical modeling was used to compute the saturation indices (SI) for product minerals in batch feldspar dissolution experiments at elevated temperatures and pressures and to trace the reaction paths on activity–activity diagrams. The modeling results demonstrated: (1) the experimental aqueous solutions were supersaturated with respect to product minerals for almost the entire duration of the experiments; (2) the aqueous solution chemistry did not evolve along the phase boundaries but crossed the phase boundaries at oblique angles; and (3) the earlier precipitated product minerals did not dissolve but continued to precipitate even after the solution chemistry had evolved into the stability fields of minerals lower in the paragenesis sequence. These three lines of evidence signify that product mineral precipitation is a slow kinetic process and partial equilibria between aqueous solution and product minerals were not held. In contrast, the experimental evidences are consistent with the hypothesis of strong coupling of mineral dissolution/precipitation kinetics [e.g., Zhu C., Blum A. E. and Veblen D. R. (2004a) Feldspar dissolution rates and clay precipitation in the Navajo aquifer at Black Mesa, Arizona, USA. In Water–Rock Interaction (eds. R. B. Wanty and R. R. I. Seal). A.A. Balkema, Saratoga Springs, New York. pp. 895–899]. In all batch experiments examined, the time of congruent feldspar dissolution was short and supersaturation with respect to the product minerals was reached within a short period of time. The experimental system progressed from a dissolution driven regime to a precipitation limited regime in a short order. The results of this study suggest a complex feedback between dissolution and precipitation reaction kinetics, which needs to be considered in the interpretation of field based dissolution rates.

Indigenous Nationhood and Intertribal Kinship in Todd Downing's The Mexican Earth

As Todd Downing led tourists from the United States through Mexico during the summers in the late 1920s and early 1930s, he studied their views of Mexico and developed his own acute understanding of the Mexican land and its people. Downing incorporated this knowledge and experience into ten mystery novels and The Mexican Earth (1940), a history of indigenous Mexico and an unequivocal assertion of indigenous nationhood and anti-racist, anti-colonial nationalism disguised as a travelogue about modern Mexico. (1) Downing was born in Atoka in the Choctaw Nation, Indian Territory, now Oklahoma, in 1902, and his interest in Mexico has its origins in his intellectual life in Norman at the University of Oklahoma, where Downing earned a BA in 1924 and an MA in 1928 with a thesis on the Uruguayan dramatist Florencio Sanchez. He also taught Spanish in the Department of Modern Languages and reviewed books in Spanish and French for Books Abroad, which was founded at the University of Oklahoma and eventually renamed World Literature Today. In The Mexican Earth, which received a laudatory review from the archaeologist and historian Philip Ainsworth Means in the New York Times, Downing adopts an explicitly indigenous authorial perspective by identifying himself as Indian and narrating a map of the Americas that foregrounds an indigenous nation to indigenous nation relationship within Mexico and between Mexico and the United States. (2) Downing highlights the varied histories, worldviews, and landscapes that define indigenous nations, but also he emphasizes the shared experience of originating and continuously residing in the Americas that establishes and sustains a kinship between all indigenous American people. In a reading of the histories of the Americas he privileges tribal nation specificity and encourages indigenous solidarity against colonial dominance. Downing's view of indigenous Mexico in The Mexican Earth anticipates late-twentieth- and early-twenty-first-century coalitions between indigenous people in the US and Mexico as well as the current disciplinary interest in American Indian literary nationalism, which encourages the foregrounding of indigenous creative and intellectual traditions in readings of indigenous literatures and histories. For example, in March of 2006, a month prior to the American Literature: Nationalism and Beyond conference sponsored by the Institute of Native American Studies at the University of Georgia, twenty-five citizens of the Hopi Nation ran 2,000 miles from Hopi to Anahuac, the Valley of Mexico, for the Fourth World Water Forum in Mexico City. (3) The run was organized by the Black Mesa Trust, which was founded in 1999 to educate people about the devastating environmental impact of the Peabody Coal Company's daily pumping of millions of gallons of water from the Navajo Aquifer. (4) The runners, who ranged in age from twelve to seventy-five years, arrived at the Otomi Ceremonial Center in Temoaya and, then, completed their journey at Teotihuacan, a 2,000 year old urban center of Mesoamerica prior to the rise of Mexico-Tenochtitlan in 1325 CE. Roberto Rodriguez reports in the April 6, 2006 edition of Indian Country Today on the welcome that the Hopis received from their relatives throughout the journey and in Anahuac: Everywhere they went, the runners were treated with utmost respect and great reverence, particularly the elders. Many of those with whom they met acknowledged that they are related and that the Hopi represent memory. The people do not need linguists, archaeologists or anthropologists to affirm this. The stories, the common languages, the water and the maize communicate this same message: San ce tojuan. Ti masehualme, okichike ka centeotzintli: We are one. We are macehual, made from sacred maize. (1) This meeting of relatives only nominally separated by colonial borders illustrates at least two ways that indigenous peoples practice their nationhood in an international context: through a local movement that roots itself in an indigenous nation's land and worldview even as it travels between other native nations (Zuni, Isleta, Otomi) to a global conference on water policy, and through the recognition of indigenous nationhood by other indigenous nations. …

Using δ 87 Sr values to identify sources of salinity to a freshwater aquifer, Greater Aneth Oil Field, Utah, USA

Salinity increases in water from the freshwater Navajo aquifer in the Aneth area have been documented in recent years. Previous studies during the 1980s in the Aneth area suggested that brines associated with oil production and their subsequent re-injection were the probable source of salinity in the Navajo aquifer. Differences in the delta strontium-87 (δ 87Sr) composition of ground-water samples from southeastern Utah were used to determine if oil-field brine or water from the upper Paleozoic aquifer is a plausible source of salinity to the Navajo aquifer. The δ 87Sr values of the oil-field brine samples (mean = −0.95%, range = −1.06 to −0.79%, n = 5) are substantially more negative than the values in water samples from wells completed in the Navajo aquifer (mean = 0.73, range = −0.85 to 2.02%, n = 48), indicating that oil-field brine is not a source of salinity. The δ 87Sr values in water samples from wells completed in the upper Paleozoic aquifer (mean = 0.801% range = 0.34 to 1.10%, n = 4) are similar to the mean isotopic composition of the more saline water from the Navajo aquifer. The δ 87Sr values in water from the Navajo aquifer confirm that two distinct flow areas are present. Mixing models using the δ 87Sr values and Sr concentrations of non-saline water from the Navajo aquifer and saline water from the upper Paleozoic aquifer indicate that water from the upper Paleozoic aquifer is a plausible source of saline water to the Navajo aquifer. Most Navajo aquifer wells that contain water with a δ 87Sr signature similar to water from the upper Paleozoic aquifer are located within or adjacent to an area where the hydraulic gradient is favorable for upward movement of water from the upper Paleozoic aquifer into the Navajo aquifer.

SALINITY INCREASES IN THE NAVAJO AQUIFER IN SOUTHEASTERN UTAH1

ABSTRACT: Salinity increases in water in some parts of the Nava‐jo aquifer in southeastern Utah have been documented previously. The purpose of this paper is to use bromide, iodide, and chloride concentrations and del oxygen‐18 and deuterium values in water from the study area to determine if oil‐field brines (OFB) could be the source of increased salinity. Mixing‐model results indicate that the bromide‐to‐chloride X 10,000 weight ratio characteristic of OFB in and outside the study area could not be causing the bromide depletion with increasing salinity in the Navajo aquifer. Mixing‐model results indicate that a mixture of one percent OFB with 99 percent Navajo aquifer water would more than double the bromide‐to‐chloride weight ratio, instead of the observed decrease in the weight ratio with increasing chloride concentration. The trend of the mixing line representing the isotopically enriched samples from the Navajo aquifer does not indicate OFB as the source of isotopically enriched water; however, the simulated isotopic composition of injection water could be a salinity source. The lighter isotopic composition of OFB samples from the Aneth, Ratherford, White Mesa Unit, and McElmo Creek injection sites relative to the lsmay site is a result of continued recycling of injection water mixed with various proportions of isotopically lighter make‐up water from the alluvial aquifer along the San Juan River. A mixing model using the isotopic composition of the simulated injection water suggests that enriched samples from the Navajo aquifer are composed of 36 to 75 percent of the simulated injection water. However, chloride concentrations predicted by the isotopic mixing model are up to 13.4 times larger than the measured chloride concentrations in isotopically enriched samples from the Navajo aquifer, indicating that injection water is not the source of increased salinity. Geochemical data consistently show that OFB and associated injection water from the Greater Aneth Oil Field are not the source of salinity increases in the Navajo aquifer.

Using Geochemical Techniques to Identify Salinity Sources in the Freshwater Navajo Aquifer, Aneth Oil Field, Utah

The salinity of water in the Triassic and Jurassic Navajo Sandstone in southeastern Utah has increased locally since 1952. The Navajo aquifer, within the Navajo Sandstone, is major source of water for domestic use and livestock in the area. From 1989 to 1991, concentration of dissolved solids in one well increased by as much as 5500 mg/L. The source or sources of the saline water and the reasons for the local increases are not known; however, mixing with either oil-field brines (OFB) or non-oil-field brines (NOFB) from the Pennsylvanian Paradox Formation could possibly cause the increase salinity. One of the objectives of an ongoing study is to use end-member mixing models and step-wise discriminant analysis to determine the possible source or sources of saline water causing the observed increase in salinity in the Navajo aquifer. Discriminant analysis was used on the major-ion/chloride ratios to identify saline-water sources that could have mixed with Navajo aquifer water.