Albuquerque Basin Research Articles

An Oil and Gas Play Turns Into a Prime Helium Prospect

Black Exploration, LLC drilled a wildcat oil and gas test on a large structure on the Zia Pueblo in early 2023. The primary objectives were oil and gas. However, helium potential was also recognized as a possible secondary objective. This large structure sits adjacent to some of the largest reported air corrected mantle, He and CO2 degassing carbonic and geothermal springs in the Rocky Mountain region. The prospect overlies a classic Synthetic Overlapping Transfer Zone between the northern Albuquerque Basin and the southern Espanola Basin in the Rio Grande rift in Northern New Mexico. Recognition of possible deep crustal and upper mantel faulting as well as surface geologic mapping, gravity, seismic and geo-microbial techniques helped delineated the prospect. A possible explanation for why high mantle derived helium is concentrated in this area is the intersection of the ancient Jemez Lineament and the more recent Rio Grande rift. This wildcat has now discovered helium and white hydrogen in the Abo formation. If economically productive the well will be the first helium discovery in the Rio Grande Rift. This could open the rift and its sub basins into a large, new oil, gas and helium and hydrogen producing province.

The Seismic Signature of a High-Energy Density Physics Laboratory and Its Potential for Measuring Time-Dependent Velocity Structure

Abstract The Z Machine at Sandia National Laboratories is a pulsed power facility for high-energy density physics experiments that can shock materials to extreme temperatures and pressures through a focused energy release of up to ∼25 MJ in <100 nanoseconds. It has been in operation for more than two decades and conducts up to ∼100 experiments, or “shots,” per year. Based on a set of 74 known shot times from 2018, we determined that Z Machine shots produce detectable ∼3–17 Hz ground motion 12 km away at the Albuquerque Seismological Laboratory, New Mexico (ANMO), borehole seismograph, with peak signal at ∼7 Hz. The known shot waveforms were used to create a three-component template, leading to the detection of 2339 Z Machine shots since 1998 through single-station cross-correlation. Local seismic magnitude estimates range from local magnitude (ML) −2 to −1.3 and indicate that only a small fraction of the shot energy is transmitted by seismic phases observable at 12 km distance. The most recent major facility renovation, which was intended to decrease mechanical dissipation, is associated with an abrupt decrease in observed seismic amplitudes at ANMO despite stable maximum shot energy. The highly repetitive impulsive sources are well suited to coda-wave interferometry to investigate time-dependent velocity structures. Relative velocity variations (dv/v) show an annual cycle with amplitude of ∼0.2%. Local minima are observed in the late spring, and dv/v increases through the summer monsoon rainfall, possibly reflecting patchy saturation as rainfall infiltrates near the eastern edge of the Albuquerque basin. The cumulative results demonstrate that forensic seismology can provide insight into long-term operation of facilities such as pulsed-power laboratories, and that their recurring signals may be valuable for studies of time-dependent structure.

Climate Change Impacts on Agricultural Water Availability in the Middle Rio Grande Basin

AbstractWe present a comprehensive analysis of water availability under plausible future climate conditions in a heavily irrigated agricultural watershed located in the middle section of the Rio Grande Basin in the United States Desert Southwest. Future managed streamflow scenarios (through year 2099) were selected from among 97 scenarios developed based on downscaled, bias‐corrected global climate model outputs to evaluate future inflows to the principal surface water storage reservoirs, possible future reservoir releases, and groundwater pumping to sustain irrigated agriculture. The streamflow projections describe a wide range of dry and wet conditions compared to the average historical flows in the river, indicating significant uncertainty in future water availability in the Rio Grande Basin. We applied the Soil and Water Assessment Tool to illustrate the impact of climate futures on different components of the water budget at a watershed scale. Results indicate declining reliability of reservoir storage to meet the water demand of irrigated agriculture. The impact of declining surface water can be offset by increasing the pressure on the already‐strained groundwater resources. However, the region should be prepared to use slightly saline (total dissolved solids [TDS] > 1,000 mg/L) and moderately saline groundwater (TDS > 3,000 mg/L) as fresh groundwater in the regional aquifer is depleted within the 21st Century under hotter and drier conditions and status quo agricultural land and water management practices.

Least-Cost Provision of Ecosystem Services from Water: When, Where, and How Much?

Changes in surface or groundwater management influence water use patterns as well as the economic value and sustainability of all water uses. In water-scarce regions, programs that establish environmental flows usually involve reallocating water from another productive use. Few peer-reviewed papers to date have investigated impacts on system-wide economic performance resulting from environmental flow regimes. This work presents an original approach to address that gap by developing and applying a basin-scale hydroeconomic optimization model of North America’s Middle Rio Grande Basin to explore impacts of environmental pulse flows on the region’s economy and water stocks. The model accounts for surface and groundwater storage, irrigation, urban, recreational, and environmental demands; surface water inflows under various climate scenarios; groundwater pumping and recharge; substitute water prices; crop water use; evaporation; as well as institutional constraints governing water use. Results show that climate change, in the form of highly variable inflows, has an impact on the total and marginal cost of implementing environmental pulse flows, amplified by the conjunctive nature of the system.

Impacts of Urbanization and Intensification of Agriculture on Transboundary Aquifers: A Case Study

AbstractThe objectives were to (1) delineate the complex set of rules governing the fate and transfer of water rights as agricultural land is urbanized in Texas and New Mexico in the United States and Chihuahua in Mexico and (2) estimate the change in water use as a result of such urbanization. Important additional determinants of water use in the region include intensification of agriculture and the hydroschizophrenic policy framework. We conducted interviews with key informants to identify the possible outcomes for changes in water rights as land is urbanized. We constructed decision trees for each of the three jurisdictions, Chihuahua, Texas, and New Mexico, that identified the possible outcomes from urbanization. For each of the possible outcomes in the decision tree, we estimated a range of potential water use outcomes and the most likely water use outcome on a per unit of land area basis. Results show that urbanization of agricultural land has almost no impact on the aggregate demand for or use of surface water. However, the impacts of urbanization on groundwater use vary considerably over the region from Texas to New Mexico to Chihuahua. In New Mexico and Chihuahua where groundwater rights can be leased or sold to other users, the likely impact is a net increase in groundwater use as land is urbanized, ranging from 0 to 3,000 m3/ha in New Mexico and averaging 3,000 m3/ha or more in Chihuahua. In Texas, there is a net benefit in groundwater savings, but those savings are subject to being offset by increased groundwater pumping to meet the needs of expanding pecan production. The net result is continued groundwater depletion, threatening the life of the transboundary aquifers, the Hueco Bolson and the Mesilla Bolson, in the Middle Rio Grande basin (defined as the part of the basin between Elephant Butte Reservoir in New Mexico to the confluence of the river with the Rio Conchos from Mexico).

Resource risk and stability in the zooarchaeological record: the case of Pueblo fishing in the Middle Rio Grande, New Mexico

Disarticulated fish remains are frequently recovered from late preHispanic and early historic archaeological sites in the Middle Rio Grande basin of central New Mexico, but they are rare during earlier time periods. Increased aquatic habitat quality brought on by wetter climatic conditions may have impacted Ancestral Pueblo foraging goals related to risk minimization, leading to an uptick in fish exploitation. Wetter stream conditions can increase the number of different energy channels that help support fish populations and increase ecological stability, which makes fish less risky to pursue for human foragers. Here, we illustrate how to identify stable ecological communities in the archaeological record using stable carbon and nitrogen isotope values of fish bones recovered from archaeological sites in the Middle Rio Grande. We find that energy derived from terrestrial C4 plants—a stabilizing “slow” allochthonous energy source—was important for the Middle Rio Grande aquatic food web during the late preHispanic/early historic period. This result suggests that fish populations were supported by a broader resource base and were thus more stable and less risky to pursue for Ancestral Pueblo people.

Linking Hydrobiogeochemical Processes and Management Techniques to Close Nutrient Loops in an Arid River

In this study, we explore opportunities to optimize food-energy-water (FEW) resources by closing nutrient loops in arid-land rivers. Specifically, we evaluate source and sink behavior of nitrogen as nitrate (NO3-N) in three characteristic channels in the Middle Rio Grande Basin (Delivery and Drain channels associated with agriculture and the main channel of the Rio Grande). All three channels are located downstream of a large wastewater treatment plant that is the main contributor of nutrients to this reach of the Rio Grande. We used a mass balance approach paired with stable isotope analysis to determine sources and processing of NO3-N within the channels over time (a year) and through space (along ~15 to 50 km reaches). Results indicated the growing season was an important period of sink behavior for the Delivery channel and the Rio Grande, but the Drain channel was a year-round source. Stable isotope analysis of 15N and 18O found a distinct nitrate signature in the Drain associated with biological processing, as well as Rio Grande sites impacted by agricultural outflow, but no equivalent signature was present in the Delivery channel. Based on our findings, we provide recommendations to help close nutrient loops in the study system and analogous aridland irrigation networks by 1) minimizing loss during the transfer of nutrients from wastewater facilities to agricultural areas, and 2) minimizing enrichment to downstream aquatic ecosystems by sequestering nutrients that escape the nutrient loop.

A Comprehensive Process for Stakeholder Identification and Engagement in Addressing Wicked Water Resources Problems

Various sectors of stakeholders (urban, agricultural, policymakers, etc.) are frequently engaged in participatory research projects aimed at improving water resources’ sustainability. However, a process for comprehensive and integrative identification, classification, and engagement of all types of water stakeholders for a region or river basin, especially in a transboundary context, is missing for water resources research projects. Our objective was to develop a systematic approach to identifying and classifying water stakeholders, and engage them in a discussion of water futures, as a foundation for a participatory modeling research project to address the wicked water resource problems of the Middle Rio Grande basin on the U.S./Mexico border. This part of the Rio Grande basin can be characterized as having limited and dwindling supplies of water, increasing demands for water from multiple sectors, and a segmented governance system spanning two U.S. states and two countries. These challenges are being exacerbated by climate change; a transitioning agriculture to more water demanding, high value crops; urbanization; and growing demand for environmental services. Moving forward, a core question for this region is how can water be managed so that the three competing sectors—agricultural, urban, and environmental—can realize a sustainable future in this challenged water system? We identified the major water-using sectors who represent competing demands as including agricultural, municipal, self-supplied industrial users, environmental, and a sector we labeled “social justice”, comprised of individuals who lack access to potable water, or who represent groups who advocate for access to water. We included stakeholders from both the U.S. and Mexico, which is seldom done, who share transboundary water resources in the region. We hosted a series of stakeholder dialogues and obtained results that identified and described their vision for the future of water; challenges to be overcome; and important research questions that could be addressed using participatory modeling approaches. Four broad themes common to multiple sectors emerged: (1) quantity, drought, and scarcity; (2) quality/salinization; (3) urbanization; and (4) conservation and sustainability. Each sector expressed distinctive views regarding the future of water. Agricultural stakeholders, in particular, had strong feelings of ownership of water rights as part of land ownership and a concomitant sense of threat to those water rights emanating from dwindling supplies and competing demands. The contribution of this work is a methodology for identifying, classifying, and engaging all types of stakeholders in the context of a research project, enabling us to compare and contrast views of different types of stakeholders. Heretofore, this has been accomplished in “bits and pieces”, but never comprehensively and holistically.

Teleseismic Scattered‐Wave Imaging Using a Large‐N Array in the Albuquerque Basin, New Mexico

AbstractThe advent of low‐cost continuously recording cable‐free autonomous seismographs, commonly referred to as nodes, enables dense spatiotemporal sampling of seismic wavefields. We create virtual source reflection profiles using P waves from five teleseismic events recorded by the Sevilleta node array experiment in the southern Albuquerque basin. The basin geology records a structurally complex history, including multiple Phanerozoic orogenies, Rio Grande rift extension, and ongoing uplift from a midcrustal magma body. The Sevilleta experiment densified the long term, regionally sparse seismograph network with 801 single channel vertical‐component 10 Hz geophone nodes deployed at ∼300 m spacing for 14 days in February 2015. Results show sediment‐basement reflections at <5 km depth and numerous sub‐basin structures. Comparisons to legacy crustal‐scale reflection images from the Consortium for Continental Reflection Profiling show agreement with structural geometries in the rift basin and upper crust. Comparisons of the teleseismic virtual reflection profiles to synthetic tests using 2D finite‐difference elastic wave propagation show strong P‐to‐Rayleigh scattering from steep basin edges. These high‐amplitude conversions dominate the record sections near the western rift margin and originate at the Loma Pelada fault, which acts as the primary contact between rift‐bounding basement‐cored fault blocks and rift basin sediments. At near offsets, these signals may interfere with interpretation of upper crustal structure, but their relatively slow moveout compared to teleseismic P‐wave multiples provides clear temporal separation from sediment‐basement reflections across most of the array. The high‐signal‐to‐noise ratio of these converted Rayleigh‐wave signals suggests that they may be useful for constraining short‐period (∼1 Hz) dispersion with strong sensitivity in the uppermost ∼1 km of the rift basin sediments.

Empirical Application of Rubinstein Bargaining Model in Western U.S. Water Transactions

Water transactions are proposed as a policy tool for increasing regional drought resilience and improving allocative efficiency. However, water trading deviates considerably from classical competitive markets and alternative theoretical approaches are useful for understanding water market structure and performance. In this paper, we model a bilateral water transaction using a non-cooperative bargaining model. Then we empirically test predictions regarding time preference, outside options, and water supply risk. The econometric analysis encompasses two transaction regions: Colorado’s Front Range and New Mexico’s Middle Rio Grande Basin. We find evidence suggesting that larger cities pay lower prices in water transactions, faster growing and higher income cities pay higher prices and that prices are higher when snowpack variability is higher. Findings suggest that a stronger time preference results in a less favorable price for urban buyers and that buyer risk-aversion is a greater disadvantage in bargaining in locations with greater water supply variability.

The economics of aquifer protection plans under climate water stress: New insights from hydroeconomic modeling

Where surface and groundwater are managed conjunctively, the stress on water supplies from climate change can significantly influence water use patterns as well as the economic value and sustainability of those uses. However, aquifer protection can be an expensive proposition because water uses that currently rely on aquifer pumping may produce considerable economic value that would be lost if protection measures are carried out. Evidence from climate-stressed regions has attracted research addressing the costs and benefits of aquifer protection plans. Despite these efforts, few peer-reviewed papers have examined water use patterns that minimize the economic costs of aquifer protection. This work presents an original approach to address that gap by developing and applying a basin scale hydroeconomic optimization model of North America’s Middle Rio Grande Basin to explore impacts of new policies not yet implemented supporting aquifer protection. It also gives model access to readers or stakeholders to experiment with their own scenarios to assess impacts of alternative aquifer protection plans. The model accounts for surface and groundwater storage, irrigation, urban, environmental, and recreational demands, surface water inflows under various climate scenarios, groundwater pumping and recharge, substitute water prices, crop water use, evaporation, as well as institutional constraints governing water use. The objective is implemented by finding the optimized discounted net present value of economic benefits summed over uses, sectors, and regions from use of surface water and connected aquifers. Results are shown for each of six water supply scenarios, two substitute water prices, and two system operation rules. To address impacts of aquifer protection targets, groundwater sustainability targets are specified and enforced as constraints for each of the region’s two major aquifers. We assess total and marginal cost of achieving two targeted aquifer protection levels by identifying optimized surface use and groundwater pumping for each of 24 scenarios. Results show that climate change, in the form of reduced and highly variable inflows, considerably drives up the cost of protecting aquifer sustainability, amplified by the conjunctive nature of the system. Future work points to a need to assess economic performance of various water conservation measures as well as reducing costs of substitute water through measures such as technical advance in desalination, recycling and reuse, substitution of other resources for water, better characterization of existing aquifers, and development of new groundwater supplies.

Monitoring of Land Use/Land-Cover Changes in the Arid Transboundary Middle Rio Grande Basin Using Remote Sensing

Expanding urbanization in highly fragile desert environments requires a thorough understanding of the current state and trends of land uses to achieve an optimal balance between development and the integrity of vital ecosystems. The objectives of this study are to quantify land use change over the 25-year period 1990–2015 and analyze temporal and spatial urbanization trends in the Middle Rio Grande Basin. We conclude by indicating how the results can inform on-going water resource research and public policy discussion in an arid region. Results show that the predominant upland mixed vegetation land cover category has been steadily declining, giving up land to urban and agricultural development. Urban development across the region of interest increased from just under three percent in 1990 to more than 11 percent in 2015, mainly around the major urban areas of El Paso, Ciudad Juárez, and Las Cruces. Public policy aspects related to results from this study include transfer of water rights from agriculture to land developers in cities, higher risk of flooding, loss of natural ecosystems, and increased water pollution from point and non-point sources. Various stakeholders can find the study useful for a better understanding of historical spatial and temporal aspects of urban development and environmental change in arid regions. Such insights can help municipal authorities, farmers, and other stakeholders to strike a balance between development needs and protecting vital ecosystems that support the much needed development, especially in regions that are endowed with transboundary natural resources that often are incompletely represented in single nation data.

Puebloan Agriculture and its Impact on the Migratory Behavior of Birds

Towards the end of the thirteenth century, the Albuquerque Basin of New Mexico saw a significant increase in population from Puebloan peoples migrating into the valley. By the time of the Coronado expedition in 1541–1542, this area contained 12 large pueblos along the roughly 55 km long by 5 km wide Rio Grande floodplain, resulting in one of the densest concentrations of pueblos and agricultural fields in the Eastern Pueblo region. Zooarchaeological analyses of Classic Period faunal assemblages have yielded an abundance and diversity of wild bird remains with an emphasis towards migratory birds that reside in the region during the winter. These avifauna are almost entirely absent from the archaeological record of the preceding Developmental Period. This paper argues that changes in Puebloan farming practices between the two periods had a direct effect on shifting the traditional wintering grounds of these migratory birds northwards into the Albuquerque Basin.

Turkeys on the fringe: Variable husbandry in “marginal” areas of the prehistoric American Southwest

Previous research reporting stable carbon (δ13C) and nitrogen (δ15N) isotope values of prehistoric turkey (Meleagris gallopavo) remains from the American Southwest indicates that these birds were husbanded in consistent ways: the majority of samples suggest a diet dominated by maize, a domesticate that uses the C4 photosynthetic pathway. However, most of these studies have focused on turkey remains from locations where maize would likely have been readily available. Here we present isotope and mitochondrial DNA (mtDNA) haplotype data from turkey remains from the relatively high-elevation site of Tijeras Pueblo (LA 581), a location where maize production may have been marginal. The Tijeras Pueblo turkeys display a unique carbon isotope pattern in both bone collagen and bone apatite, with half the samples indicating a predominately C3 diet (a signature characteristic of modern wild turkeys) and the other half predominately C4, even though the majority of samples belong to the Southwestern domestic turkey mtDNA lineage identified by Speller et al. (2010). Comparative collagen samples from the Albuquerque Basin and the Gallina region do not follow this pattern. Apatite-collagen δ13C spacing in the Tijeras turkeys suggests these birds were acquiring carbohydrates and protein from a mixture of C3- and C4-based resources. We propose that the C3 Tijeras turkeys were free-ranged, and that the presence of two distinct turkey husbandry regimes at Tijeras Pueblo may reflect Tijeras' geographic location on a cultural boundary between the Plains and Pueblo regions.

Conchas crayfish (Orconectes deanae) recognized as an alien species in the Middle Rio Grande Basin, New Mexico

Abstract We document the conchas crayfish (Orconectes deanae) as another introduced crayfish in the middle Rio Grande. We collected O. deanae in the Rio Grande and its associated ditches between Belen and La Joya, New Mexico. We did not collect O. deanae from the adjacent Pecos River; further sampling is necessary to determine the full range and impact of this alien species in the Rio Grande drainage.

Secondary Raw Material Sources of Pedernal Chert in the Albuquerque Basin, New Mexico

Prehistoric quarries targeted primary outcrops of Pedernal chert at Cerro Pedernal and San Pedro Peaks in north-central New Mexico. A long-standing tradition of secondary-source Pedernal chert use is also evident throughout the archaeological record of the Albuquerque Basin. Santa Fe Group gravels distributed across the basin contain abundant recycled Pedernal chert clasts that provide an important locally available source of this lithic raw material. LA-ICP-MS analysis of Pedernal chert collected from primary sources, Santa Fe Group gravels, and Pedernal chert artifacts from the basin revealed no significant chemical differences among these materials. Pedernal chert is most often associated with its primary source at Cerro Pedernal; however, geologic evidence reveals that recycled Pedernal chert clasts within Albuquerque Basin gravel deposits most likely originated from outcrops along the San Pedro–Sierra Nacimiento range. Size distributions among Pedernal chert gravels found within differing portions of the Albuquerque Basin present specific limitations on lithic reduction strategies. As such, regional settlement distributions and lithic assemblage variability reflect patterned variation in the use of these secondary deposits through time.

Synchronous opening of the Rio Grande rift along its entire length at 25–10 Ma supported by apatite (U-Th)/He and fission-track thermochronology, and evaluation of possible driving mechanisms

One-hundred and forty-seven new apatite (U-Th)/He (AHe) ages are presented from 32 sample locations along the flanks of the Rio Grande rift in New Mexico and Colorado. These data are combined with apatite fission-track (AFT) analyses of the same rocks and modeled together to create well-constrained cooling histories for Rio Grande rift flank shoulders. The data indicate rapid cooling due to extension from ca. 28 to 5 Ma in the Sawatch Range, ca. 28 Ma to Quaternary in the Sangre de Cristo Mountains, ca. 25 to 5 Ma in the Albuquerque Basin, and ca. 25 to 10 Ma in the southern Rio Grande rift in southern New Mexico. Rapid cooling of rift flanks followed the Oligocene ignimbrite flare-up, and the northern section of the Rio Grande rift in Colorado exhibits semicontinuous cooling since the Oligocene. Overall, however, rift flank cooling along the length of the rift was out of phase with high-volume magmatism and hence is inferred to have been driven mainly by exhumation due to faulting. Although each location preserves a unique cooling history, when combined with existing AHe data from the Gore Range in northern Colorado and the Sandia Mountains in New Mexico, together these data indicate that extension and exhumation of rift shoulders were synchronous along >850 km of the length of the Rio Grande rift from 25 to 10 Ma. These time-space constraints provide an important new data set with which to develop geodynamic models for initiation and evolution of continental rifting. Models involving northward propagation of rifting and Colorado Plateau rotation are not favored as primary mechanisms driving extension. Instead, a geodynamic model is proposed that involves upper-mantle dynamics during multistage foundering and rollback of a segment of the Farallon plate near the Laramide hinge region that extended between the Wyoming and SE New Mexico high-velocity mantle domains. The first stage of flat slab removal accompanied ca. 40–20 Ma volcanism in the San Juan and Mogollon-Datil ignimbrite centers, which initiated asthenospheric upwelling and circulation. A second stage involved a ca. 30–25 Ma detachment of remaining fragments of the Farallon slab, intensifying asthenospheric upwelling and focusing it along a N-S trend beneath Colorado and New Mexico. By 25 Ma, the North American lithosphere had become weakened critically along this narrow zone, so that extension was accelerated, resulting in the observed 25–10 Ma cooling indicated by the thermochronologic data. This developed a central graben with increased fault-related high strain rates and resulted in maximum sediment accumulation in the Rio Grande rift. Our geodynamic model thus involves Oligocene removal of parts of the Farallon slab beneath the ignimbrite centers followed by a major Oligocene–Miocene slab break that instigated the discrete N-S Rio Grande rift through focused upper-mantle convection beneath the southern Rocky Mountain–Rio Grande rift region.

Embryonic core complexes in narrow continental rifts: The importance of low-angle normal faults in the Rio Grande rift of central New Mexico

The Rio Grande rift in central New Mexico provides an excellent location to study the interaction between high-angle and low-angle (15°–35°) normal faults during crustal extension. Here we evaluate the relative importance of low-angle normal faults (LANFs) in the Albuquerque basin of central New Mexico with goals of testing two conflicting models of rift geometry and producing evolutionary models for the northern and southern parts of the basin. Using physiographic relationships, field observations, structural data analysis, and thermal history modeling, we document two brittle LANF systems on salients in adjacent opposite-polarity half-grabens. These fault systems were both active ca. 20–10 Ma and are locations of maximum fault slip as indicated by thickness of sedimentary fill in adjacent sub-basins and highest elevation rift flanks. Average fault dip increases basinward, and outbound faults were abandoned while intrabasinal faults cut Quaternary units, supporting an evolutionary model where master normal faults initiated at a higher dip, were shallowed by isostatic footwall uplift in regions of highest slip, and became inactive while younger normal faults emerged basinward. These geometrical and kinematic observations are predicted by the rolling-hinge model for the formation of LANFs. This mechanism has been widely applied to core complexes in highly extended terranes (e.g., Basin and Range), regions of orogenic collapse, and mid-ocean ridges, and it is shown here to also be applicable to narrow continental rifts of modest (∼35%) extension. Similarities to core complexes include a physiographic expression of domal uplifts, evolution of a master detachment horizon that initiated as a breakaway, and isostatically rotated low-angle normal faults. Although the degree of extension was too low to juxtapose ductile footwall rocks against brittle hanging-wall rocks, if extension had progressed in the Albuquerque basin, eventually a mature metamorphic core complex would have formed, similar to those preserved in the adjacent Basin and Range Province. The Rio Grande rift, therefore, provides a snapshot of the embryonic stages of core complex formation, bridging the gap between mature core complexes and incipient extensional environments.

Quaternary extension in the Rio Grande rift at elevated strain rates recorded in travertine deposits, central New Mexico

Calcite-filled extension veins and shear fractures are preserved in numerous travertine deposits along the western margin of the Albuquerque Basin of the Rio Grande rift. Calcite veins are banded and show geometries suggesting incremental cracking and calcite precipitation. U-series and 234U model ages from calcite infillings indicate that vein formation was active in the Quaternary, from ca. 2 Ma to ca. 250 ka. Vein orientations are systematic within each deposit and record a dominant extension direction that was horizontal and varied from E-W to NW-SE, consistent with both the regional finite extensional strain in the rift and with the global positioning system (GPS)–constrained deformation field. Three sites contain three orthogonal vein sets that crosscut one another nonsystematically, suggesting alternating times of: (1) regional E-W horizontal extension (dominant), (2) alternating N-S and E-W vertical veins that suggest vertical s1 and s2 » s3, and (3) horizontal veins that are interpreted to reflect times of highest pore fluid pressures and subequal principal stresses. One site contains conjugate normal faults that also record the dominant E-W extensional tectonic stress. Quaternary extensional strain rates calculated from vein opening for three locations range from 3.2 ± 1.4 × 10–16 s–1 to 3.2 × 10-15 ± 2.7 × 10–16 s–1, which are up to ∼40 times higher than the long-term (Oligocene–Holocene) finite strain rates calculated for different basins of the Rio Grande rift (8.5 × 10–17 to 4.5 × 10–16 s–1), and up to ∼100 times higher than modern strain rates measured by GPS data (3.9 × 10-17 ± 6.3 × 10–18 to 4.4 × 10-17 ± 6.3 × 10–18 s–1). These high Quaternary rates are comparable to modern strain rates measured in the Basin and Range Province and East African Rift. Thus, this paper documents persistent E-W regional extension through the Quaternary in the Rio Grande rift that bridges geologic, paleoseismic, and GPS rates. Anomalously high strain rates in the Quaternary were facilitated by ascent of travertine-depositing CO2-rich waters along rift-bounding normal faults, leading to locally very high stain accumulations. These sites also provide examples of natural leakage of deeply sourced CO2 interacting with regional tectonism, and they emphasize that rift maturation is a highly dynamic process, both spatially and temporally.

Price determination and efficiency in the market for water rights in New Mexico's Middle Rio Grande Basin

Water rights markets in the western United States have expanded over the last 40 years, as a result of population growth in the West and Southwest, and limited development of new storage. Until 2008, house prices, home construction and population growth appeared to be locked in an ever-increasing upward trend. With little historical experience to the contrary, water right market prices similarly appeared to be driven by real estate development. The collapse of the housing market in the last four years provides an opportunity to examine the connection between the real estate and water markets. It is found that Middle Rio Grande Basin water right prices are influenced by housing prices, per capita income in the buyer's county, buyer type, point of diversion, and transaction volume. However, significant price dispersion remains, raising the question of how efficiently this market is currently working.