Yeso Formation Research Articles

Pore structure and fluid uptake of the Yeso, Abo, and Cisco Formations in the Permian Basin in southeast New Mexico, USA

There is a need for a petrophysical understanding of producing formations in the Northwest Shelf in southeast New Mexico. Working with six rotary sidewall core samples (dolomite, limestone, and sandstone), we have investigated the utility of mercury injection capillary pressure (MICP), contact angle, fluid imbibition, as well as logging analyses to evaluate the characteristics of pore structure and fluid uptake of the Yeso (Paddock and Blinebry members), Abo, and Cisco Formations. Results from MICP tests provide a variety of pore structure data including bulk and particle densities, porosity, pore-throat size distribution, permeability, and tortuosity. Two Abo dolomite samples indicate the highest porosities at greater than 15%, compared with 4%–7% for the other two dolomite samples from the Paddock and Blinebry members within the Yeso Formation. Most of the pore-throat sizes for these samples fall within the range of [Formula: see text]. The only exceptions are the Paddock member sample, which possesses a higher percentage of larger pores ([Formula: see text]), and the dolomite sample from the Cisco Formation, which has most of its pore-throat sizes falling within the range of [Formula: see text]. From contact angle measurements, all samples are found to be oil-wet because n-decane spreads onto the rock surface much quicker than the other hydrophilic fluids (deionized water and brine). Imbibition tests reveal well-connected pore networks in all samples, with the highest values of imbibition slopes being recorded for the Abo samples. In addition, we used the crossplot of porosity and water saturation obtained from log analyses to derive a value for permeability at field scales. The porosity and permeability values, from log analyses as well as laboratory MICP and gas pycnometry-permeameter measurements, and at different observational scales, are generally consistent. The overall results provide a snapshot of the pore structure characteristics, from limited samples but using integrated approaches and scales, of these formations.

(美国)新墨西哥州中南部沙加缅度山脉地下水补给的量和位置

The Sacramento Mountains and the adjacent Roswell Artesian Basin, in south-central New Mexico (USA), comprise a regional hydrologic system, wherein recharge in the mountains ultimately supplies water to the confined basin aquifer. Geologic, hydrologic, geochemical, and climatologic data were used to delineate the area of recharge in the southern Sacramento Mountains. The water-table fluctuation and chloride mass-balance methods were used to quantify recharge over a range of spatial and temporal scales. Extrapolation of the quantitative recharge estimates to the entire Sacramento Mountains region allowed comparison with previous recharge estimates for the northern Sacramento Mountains and the Roswell Artesian Basin. Recharge in the Sacramento Mountains is estimated to range from 159.86 × 106 to 209.42 × 106 m3/year. Both the location of recharge and range in estimates is consistent with previous work that suggests that ~75 % of the recharge to the confined aquifer in the Roswell Artesian Basin has moved downgradient through the Yeso Formation from distal recharge areas in the Sacramento Mountains. A smaller recharge component is derived from infiltration of streamflow beneath the major drainages that cross the Pecos Slope, but in the southern Sacramento Mountains much of this water is ultimately derived from spring discharge. Direct recharge across the Pecos Slope between the mountains and the confined basin aquifer is much smaller than either of the other two components.

Lithostratigraphy, Paleontology, Biostratigraphy, and Age of the Upper Paleozoic Abo Formation Near Jemez Springs, Northern New Mexico, USA

In the Jemez Springs area of Sandoval County, northern New Mexico, siliciclastic red beds of the upper Paleozoic Abo Formation are well exposed and yield fossil plants and vertebrates. The local Abo Formation section is more than 190 m thick and rests disconformably on the Upper Pennsylvanian Guadalupe Box Formation and is conformably overlain by the Lower Permian DeChelly Sandstone (Yeso Group). Abo sandstone sheets are low sinuosity river deposits, and intercalated sandstone beds and lenses represent sheet splays and minor channel fills that formed during overbank flooding. The dominant Abo lithofacies is mudstone, which represents floodplain deposits, many with calcareous paleosols. Fossils are present in three stratigraphie intervals of the lower to middle Abo Formation. All three intervals yield eupelycosaur-dominated vertebrate fossil assemblages of Coyotean age (Coyotean = late Virgilian-Wolfcampian on the North American provincial marine timescale: Lucas 2006). The lowest interval also yields the Spanish Queen Mine paleoflora of pteridosperms and conifers. Strata of the Guadalupe Box Formation disconformably below the Abo Formation contain late Virgilian fusulinids. We correlate the Abo Formation fossil assemblages in the Jemez Springs area to the Coyotean-age fossil assemblages in the upper part of the El Cobre Canyon Formation in the Arroyo del Agua area and in the Canon del Cobre in the Chama basin of northern New Mexico. This suggests a middle Wolfcampian age for the Jemez Springs area fossil assemblages, an age very close to the Pennsylvanian-Permian boundary.

Aquifer composition and the tendency toward scale-deposit formation during reverse osmosis desalination — examples from saline ground water in New Mexico, USA

Desalination is expected to make a substantial contribution to water supply in the United States by 2020. Currently, reverse osmosis is one of the most cost effective and widely used desalination technologies. The tendency to form scale deposits during reverse osmosis is an important factor in determining the suitability of input waters for use in desalination. The tendency toward scale formation of samples of saline ground water from selected geologic units in New Mexico was assessed using simulated evaporation. All saline water samples showed a strong tendency to form CaCO3 scale deposits. Saline ground water samples from the Yeso Formation and the San Andres Limestone showed relatively stronger tendencies to form CaSO4·2H2O scale deposits and relatively weaker tendencies to form SiO2(a) scale deposits than saline ground water samples from the Rio Grande alluvium. Tendencies toward scale formation in saline ground water samples from the Dockum Group were highly variable. The tendencies toward scale formation of saline waters from the Yeso Formation, San Andres Limestone, and Rio Grande alluvium appear to correlate with the mineralogical composition of the geologic units, suggesting that scale-forming tendencies are governed by aquifer composition and water-rock interaction.

Arthropod trace fossils from the Permian De Chelly Sandstone, northeastern Arizona

Four previously undescribed arthropod trackways from the Lower Permian De Chelly Sandstone of northeastern Arizona are assigned toPaleohelcuraandOctopodichnus, originally described from the Coconino Sandstone (Lower Permian) of northeastern Arizona. In addition toP. dunbariandO. minor, a new ichnospecies,O. raymondi, is described. Analysis of the De Chelly specimens, and comparison with similar tracks from the Coconino Sandstone and with experimental traces produced by modern arthropods, clarifies some problems in arthropod trace fossil analysis. The experiments support earlier hypotheses that spiders and scorpions were possible trail makers for the Coconino and De Chelly trackways, and show that features of these tracks can be used to determine direction of movement. These experiments also reaffirm that an animal can produce more than one morphology in a single trackway, patterns that would be classified as two distinct ichnogenera. In addition, the results of this research suggest that the tracks were made on slightly damp sand, and were preserved by being rapidly covered with dry sand.

Cyclic Sedimentation, Depositional Environments, and Facies Distribution of the Permian Paddock Member of the Yeso Formation, Vacuum (Glorieta) Field, Northwest Shelf of the Permian Basin

The Vacuum (Glorieta) field is located on the northwest shelf of the Permian basin in central Lea County, New Mexico. Cumulative oil production of 62 MMBO is primarily from the upper 100 ft of the Leonardian Paddock Member of the Yeso Formation. Cores from 10 wells were examined to identify lithologies and facies relationships. Five lithofacies were identified: (1) fine-grained quartz sandstone/siltstone facies, (2) pelletoid mudstone facies, (3) skeletal packstone/wackestone facies, (4) oolitic-pelletoid grainstone facies, and (5) crystalline dolomite facies. These lithofacies occur sequentially in four shoaling-upward cycles that can be correlated throughout much of the study area. Three major depositional environments are recognized in the Paddock Member of the Yeso Formation: (1) a subtidal open-marine environment in which the oolitic grainstone facies was deposited, (2) a subtidal protected shallow-marine environment where the skeletal packstone/wackestone facies was deposited, and (3) a subtidal to supratidal restricted shallow-marine environment where the pelletoid mudstone facies accumulated. Facies analysis indicates that the Paddock Member was deposited on a broad shallow-marine shelf. Numerous shoaling-upward cycles are possibly related to worldwide Permian sea level fluctuations. Porosity development is enhanced at the upper surface of each shoaling-upward cycle by dissolution of fossil fragments and grains.

Microfacies Analysis of the Leonardian-Guadalupian Lower Member of the San Andres Formation in the Southern Sacramento Mountains, Otero County, New Mexico

The Rio Bonito Member of the San Andres Formation records a transgression of the northwestern shelf during the late Leonardian. Late Leonardian to Guadalupian marine carbonates exposed in the Sacramento Mountains relate a marked change from equatorial tidal flat rocks of the middle Leonardian Yeso Formation. These rocks were deposited during a worldwide sea level lowstand. The Yeso-San Andres contact, previously thought to be a gradational boundary, is here interpreted as a flooding surface resulting from the eustatic sea level rise after the lowstand. Inundation of the northwestern shelf led to deposition of the thick Andres Formation marine limestone sequence within a shallow-lagoon or shelf setting. Depositional environments are predominantly subtidal and intertidal. Microfacies include packstones of comminuted bioclasts of normal saline affinities redistributed by light currents. These shoal upward at times to Dasycladacean algal grainstones interpreted as tidal bars prograding across the lagoon or shelf. More restricted wackestones and laminated mudstones occur at the base of the section and indicate a transition from tidal flat to submerged shelf. Aggradation of sediment into the intertidal zone may have occurred cyclically during San Andres deposition. One such cycle is present over the interval exposed in the Sacramento Mountains. Intertidal rocks resemblemore » tidal flat deposits of dolostone, carbonate mudstones, and a thin tongue of quartzarenite interpeted to be Glorieta Sandstone. These rocks were previously attributed to interginguing of the Yeso with the San Andres.« less

Depositional environments of the Yeso Formation (Lower Permian), southern Caballo Mountains, New Mexico

Depositional environments of the Yeso Formation (Lower Permian), southern Caballo Mountains, New Mexico

Sedimentology and Depositional Environments of Lower Permian Yeso Formation in Northwestern New Mexico: ABSTRACT

The northwesternmost exposures of the Lower Permian (Leonardian) Yeso Formation are in uplifts that bound the southern half of the San Juan basin in northwestern New Mexico. The Yeso comprises the Meseta Blanca member and overlying San Ysidro Member. The latter is called the Los Vallos Member in the southern part of the study area. The Meseta Blanca consists of cross-stratified and horizontal to wavy-bedded sandstones of eolian-dune, sand-sheet, and sabkha origin. These facies also occur in the San Ysidro (Los Vallos), which additionally includes mud-draped, ripple-laminated sandstones of supratidal mud-flat origin, gypsiferous sandstones and siltstones of sabkha origin, and evaporite-carbonate rocks of intertidal to marine-shelf origin. Paleocurrent analysis indicates that eolian dunes in the Meseta Blanca migrated southward in the northern part of the study area. These dunes may have been extensions of the DeChelly Sandstone erg to the northwest. Dunes in the southern part of the study area shifted under variable north-south winds. This variability may reflect a seasonal onshore/offshore wind regime. Lateral facies changes in the San Ysidro (Los Vallos) indicate a juxtaposition of eolian-dune and sand-dominated sabkha environments in the northern part of the study area, with coastal-sabkha, tidal, and shelf environments in the southern part.more » Eolian dunes prograded southward over coastal sabkhas at least 12 times during deposition of the Yeso. A northward shift of all facies during middle San Ysidro deposition suggests a marine transgression from the south.« less

Stratigraphy and Depositional History, Bone Spring Formation, Lea County, New Mexico: ABSTRACT

The Bone Spring formation of the northern Delaware basin in southeastern New Mexico produces oil in Lea County from foreshelf detrital carbonate facies, such as in Scharb field. Production there comes from several intervals. Stratigraphic correlations between the various Bone Springs units and equivalent Leonardian facies of the Northwest shelf in Lea County suggest that the Bone Spring is correlative to the Yeso Formation of the Northwest shelf. The shelf facies there are divided into lower, middle, and upper Yeso. The upper part of what has generally been considered to be Wolfcamp in some areas, beneath the lowermost Bone Spring sandstone, is inferred to be lower Leonardian (lower Yeso) throughout the area studied. A model is proposed for the sedimentologic and reservoir evolution of the Bone Spring Formation in Lea County. Permian-Pennsylvanian tectonic activity provided the initial substrate for the development of a high-energy shelf edge in early Yeso time. In early middle Yeso time, the basin filled with sediments of the 3rd and 2nd Bone Spring units, and the shelf to basin transition was more subtle. As the basin subsided with infilling, a high-energy shelf edge again developed in late middle Yeso time. With continued basin infilling by 1stmore » Bone Springs facies, the shelf to basin transition again evolved into a more subtle feature. Continued basin subsidence caused infilling by a thick sequence of upper Yeso carbonate, which was capped by progradational shelf carbonates of the upper Yeso.« less

Abo Formation Alluvial Facies and Associated Basin Fill, Sacramento Mountains, New Mexico: ABSTRACT

Outcrops of the Abo Formation (Wolfcampian to early Leonardian age) in the Sacramento Mountains of south-central New Mexico record the evolution of a dry alluvial fan system as it was deposited off the pedernal uplift into the Orogrande basin. The location and orientation of present-day outcrops allow us to observe an inferred east-to-west transverse facies tract consisting of: (1) proximal alluvial fans (lower Abo), which are contiguous in places with underlying Laborcita Formation fan-deltaic sediments; (2) medial anastomosed streams (middle Abo); and (3) distal low-gradient mud-dominated flood basins characterized by either distributary streams (upper Abo) or clastic tidal flats (Lee Ranch Tongue of the Abo) with associated marine carbonates (Pendejo Tongue of the Hueco Formation). Tectonism in the Pedernal highlands, which climaxed during the Late Pennsylvanian, apparently continued well into the Wolfcampian in this region, as evidenced by a major basal Abo unconformity and distinct stacked megasequences of lower Abo alluvial fan lithofacies. However, by the middle Abo, tectonic activity had quiesced and the uplift began eroding and retreating to the north and east. By the late Abo, a pediment surface had formed that was subsequently onlapped by upper Abo and eventually Yeso Formation sediments.

Canas Gypsum Member of Yeso Formation (Permian) in New Mexico

Canas Gypsum Member of Yeso Formation (Permian) in New Mexico

Pennsylvanian and Early Permian Paleogeography, Southern Colorado Plateau and Vicinity: ABSTRACT

Abstract Pennsylvanian and Lower Permian sedimentary rocks of the southern Colorado Plateau have been the subject of much controversy concerning their correlation and origin. Correlation of rock sequences and major unconformities from the fossiliferous basins onto the adjacent shelves, where relatively unfossiliferous rocks were deposited, has provided a new interpretation in terms of regional stratigraphy and depositional analysis. The Supai Group was deposited in the Grand Canyon Embayment adjacent to the Cordilleran Geosyncline. Sediments of Morrowan, Atokan, Virgilian and Wolfcampian ages were deposited in a variety of offshore marine and shoreline environments. A persistent southwest-to-northeast-trending unstable area, herein named the Sedona Arch, confined all Supai sediments, except Virgilian, to the Grand Canyon and western Mogollon Rim regions; the other strata are truncated beneath the sub-Virgilian unconformity or undergo significant facies change across the arch. The Naco Group of Desmoinesian, Missourian, and Virgilian age was deposited on the Mogollon Shelf adjacent to the Pedregosa Basin. Except for Virgilian strata, these dominantly marine rocks are also truncated beneath the sub-Virgilian unconformity across the Sedona Arch. Thus the bulk of Supai and Naco rocks are not as closely related as most previous workers had thought. Mostly marine rocks of the Molas Formation and Hermosa Group were deposited in the Paradox Basin. The northwest-to-southeast-trending Kaibab Arch provided the barrier between these rocks and the Supai and Naco to the south. Except for several transitional units, the Supai, Naco, and Hermosa Groups were deposited in distinctly separate basins and the units do not generally intertongue. The Wolfcampian Esplanade and Cedar Mesa Sandstones and Halgaito Formation form a distinct eastward-thinning wedge of rocks west of the Sedona Arch. These high-energy marine shoreline and supratidal units grade westward into thick marine carbonate sequences of the Cordilleran Geosyncline. A widespread redbed sequence comprising the Hermit and Organ Rock Formations was deposited across the entire study area. The continental and possibly tidal deposits represent a sharp change in depositional regime from the underlying and overlying sandstone deposits. The youngest sequence of deposition studied consists of sandstone, redbed, evaporite, and carbonate rocks of the Schnebly Hill Formation and DeChelly Sandstone. These units are centered around the Holbrook Basin and represent a complex of shallow marine, high- and low-energy shoreline, eolian, and sabkha depositional environments. This depositional sequence was confined to an area east of Grand Canyon and south of the San Juan River by the Sedona and Kaibab Arches. Both formations grade upward or intertongue with the overlying Coconino Sandstone and related rocks.

Stratigraphic Analysis of Upper Permian and Lower Triassic Strata in Southern Utah

Permian sedimentation in southwestern Utah was influenced by three principal depositional areas--the Oquirrh basin in north-central Utah, the Cordilleran geosyncline in eastern Nevada, and the Quemado-Cuchillo basin on the northern shelf of the Sonoran geosyncline in east-central Arizona and west-central New Mexico. Throughout Permian time, marine sediments and well-developed beach and continental eolian sandstone equivalents were deposited within these basins and on the surrounding shelves. Each of the three depositional sites appears to have exerted influence on sedimentation during a discrete period of geologic time. Thus, while one basin was the site of sedimentation, the other two basins were relatively quiescent. Remarkably similar beach and continental sandstone deposits are related to each basin, and all these sandstones extend to a common depositional area in southwest Utah where they are interlayered. Vertical juxtaposition or interlayering of littoral and beach sandstone facies that are related to three differing sedimentational basins has been responsible for most of the problems invo ving Permian nomenclature and correlation in the Colorado Plateau province. Stratigraphic analyses show that each continental sandstone facies has a basinal stratigraphic equivalent which consists primarily of interbedded carbonate with smaller amounts of sandstone and shale. The beach and basinal equivalents present are: Cedar Mesa Sandstone equivalent to Elephant Canyon carbonates; Organ Rock Shale equivalent to Meseta Blanca Sandstone and Yeso evaporites and carbonates; Coconino Sandstone, to upper De Chelly Sandstone; White Rim Sandstone (approximately upper 80 percent), to Toroweap Formation; and upper White Rim Sandstone, to lowermost (Gamma member) Kaibab Formation. Rock units underlying the Toroweap-White Rim Formations are younger toward the south. The Kaibab Formation is a stratigraphic continuation of the Franson Member of the Park City Formation in northern Utah and southwestern Wyoming and is inferred to be time-transgressive. The Permian-Triassic boundary is recorded by a pronounced unconformity in southwesternmost Utah. Northward, the break is less pronounced and is not recognizable in north-central Utah. Early Triassic sedimentation in southern Utah appears to record cyclic response to one major subsiding sedimentational area, the Cordilleran Triassic basin, apparently with characteristic onlap relations, and at least two and possibly three of the Early Triassic Moenkopi units are not present at the Moenkopi type section in northern Arizona. The southward continuation of the Woodside Formation from southwestern Wyoming to central Utah is now recognized. The Sinbad and Timpoweap Members of the Moenkopi Formation are shown to be the same stratigraphic unit. Subsurface control suggests that the Virgin Limestone Member extends into central Utah. Structurally, most of southern Utah appears to have been a slowly subsiding shelf throughout most of Permian and Early Triassic times.

Permian Shoreline of Central New Mexico

Permian rocks of the Santa Fe-Las Vegas area, New Mexico, exhibit many shoreline characteristics, and a single cycle onlap-offlap sequence. Ripple marks, cross-bedding, bars and channels, fossils, beach-rock, facies changes, gypsum, supposed halite prints, mud cracks, traits, pebble sizes, and rock thicknesses are used to interpret this pattern. The shoreline was oriented roughly north-south, or northeast-southwest. Local hills or small mountains, and a wide coastal plain, were on the west and northwest. The sea extended toward the east and southeast. In early Permian time, the sea was advancing; in middle Permian time, retreating. The onlap-offlap cycle produced a wedge-shape body of marine Permian sediments which feathered out along a line west of the present Rio Grande. The Sangre de Cristo Formation (of upper Pennsylvanian and lower Permian age) is dominantly maroon shale, with about 20 per cent sandstone and conglomerate, representing continental deposition. The Yeso Formation is primarily orange-colored ripple-marked siltstones representing the tidal flat environment, but the upper part of the formation includes several beachrock units. The Glorieta Formation is highly cross-bedded clean sand which apparently accumulated in the near-shore environment. The Lagunita Formation is beachrock, formed early in the regressive stage. The Bernal Formation is orange-colored siltstone thought to represent the tidal flat, and supposedly deposited in middle Permian time. No late Permian rocks are known in the area. Coastal plain sediments accumulated again duri g the Triassic (Santa Rosa and Chinle Formations). Ripple marks, cross-bedding, bars, and facies changes are used to give orientations. Ripple marks, mud cracks, trails, and evaporites are used to provide information about water depths. Ripple marks, beachrock, and fossils are used to interpret specific environments. A tropical or sub-tropical climate is inferred.

Permian System of Colorado Plateau

The Permian System of the Colorado Plateau contains a variety of marine and continental sedimentary rocks deposited during Wolfcampian and Leonardian time. In southwestern Colorado and southeastern Utah the system is largely arkosic redbeds which become finer-grained and segregated into distinctive units southwestward from the source area of the Uncompahgre uplift. The redbeds were deposited on arid coastal plains closely related to shallow marine environments along the southern and western margins of the province. The removal of clastics from the source area was almost complete by the close of Wolfcamp time, for Leonardian deposits consist of eolian sandstones of wide lateral extent in the Four Corners region and marine sandstones, carbonates, and evaporites along the so thern and western plateau. Continuous sedimentation probably occurred across the Pennsylvanian-Permian temporal boundary along the margin of the Uncompahgre source area and in the San Juan and Black Mesa basins of New Mexico and Arizona. Many local areas were positive during Pennsylvanian time, but were buried by early Permian or slightly older sedimentation. Most of southeastern Utah was subjected to late Pennsylvanian or early Permian erosion that was related to intense bevelling of the Emery and Defiance uplifts where the Pennsylvanian was entirely removed. A previously used term Rico formation is abandoned because it is neither useful nor mappable. Coarse clastics of the undifferentiated Cutler Group were derived entirely from the Uncompahgre uplift, and grade laterally into the finer-grained lower Cutler in the Four Corners area, the Abo Formation of central New Mexico, and the Supai Formation of northern Arizona. The lower Cutler redbeds grade westward into the lower Halgaito redbeds, and interfinger with the overlying near-shore marine Cedar Mesa Sandstone. The lower Cutler and Halgaito clastics interfinger with marine carbonates toward the northwest. The Wolfcampian carbonates are designated the Elephant Canyon Formation in this report. The Supai Formation of the Grand Canyon represents the Halgaito and Cedar Mesa Formations, but the two-fold distinction in the Supai (restricted) of east-central Arizona is not apparent. The quivalent Supai and Abo Formations interfinger with marine carbonates toward the south and west. Lateral equivalents of the upper Cutler are the Organ Rock-Hermit redbeds, and the overlying eolian to marine De Chelly Sandstone. The Organ Rock-Hermit Shales are restricted to the Four Corners-Monument Valley-Grand Canyon areas. The De Chelly Sandstone, the youngest Permian deposits of the central Colorado Plateau are eolian over most of the province, but grade to marine sandstones along the southern extremes of the plateau. It is recommended that equivalent sandstones in east-central Arizona (formerly the upper Supai Formation) and central New Mexico (formerly the Meseta Blanca Member of the Yeso Formation) be referred to the De Chelly Sandstone of Leonardian(?) age. Post-Cutler (post-De Chelly) sedimentation was restricted to the southern and western margins of the plateau. The oldest of these deposits, the Yeso Formation (restricted) is a mixed marine association of carbonates, evaporites, and clastics that extends across the southern part of the Colorado Plateau. The overlying Coconino-Glorieta sandstone is a shallow marine deposit in central New Mexico (Glorieta) that grades westward into thick eolian deposits (Coconino). The youngest Permian deposits on the plateau End_Page 149------------------------------ are the San Andres Formation of central New Mexico, and the equivalent Kaibab-Toroweap Formations of northern Arizona and the western margin of the province in Utah. These sediments are largely shallow marine carbonates and clastics, with local occurrences of evaporites. An epeirogenic uplift occurred sometime during late Permian or early Triassic time, but the amount and time of uplift was not great for only relatively minor erosional features are known. The time lapse represented by the disconformity is the upper half of the Permian and the lowermost Triassic, but erosion took place late enough to allow thorough lithification of Permian sediments. The climate of the province was arid or semi-arid during Permian time, as shown by the preservation of redbeds and fresh feldspar detritus, and the presence of vast dune deserts and extensive evaporite deposits throughout the system.

STRATIGRAPHY OF UPPER PENNSYLVANIAN AND LOWER PERMIAN ROCKS IN THE SAND CANYON AREA, OTERO COUNTY, NEW MEXICO

The Magdalena Group of Pennsylvanian age and, in ascending order, the lower tongue of the Abo Sandstone (herein named the Danley Ranch Tongue), the Hueco Limestone, the upper tongue of the Abo Sandstone (herein named the Lee Ranch Tongue), and the Yeso Formation of Permian age are well displayed in the southern part of the Sacramento Mountains. The contact of the Pennsylvanian rocks with the overlying Permian rocks is unconformable throughout the area. Locally the relief before deposition of the Abo was so great that in places the Danley Ranch Tongue of the Abo is absent because of nondeposition. At these places there is prominent angular discordance between the Pennsylvanian and Permian rocks. The red beds of the Danley Ranch Tongue interfinger with and grade southward into the overlying Hueco Limestone. Red beds of the Lee Ranch Tongue of the Abo Sandstone also grade southward into the Hueco and cannot be traced south of the southern part of the Sacramento Mountains. The Lee Ranch Tongue is believed to be stratigraphically lower than the Deer Mountain Red Shale Member of the type Hueco Limestone. The herein named Otero Mesa Member of the Yeso Formation is believed to occupy an intermediate stratigraphic position between the Lee Ranch Tongue and the Deer Mountain Red Shale.

Structural control of uranium ore at the Monument No. 2 mine, Apache County, Arizona

The Monument No. 2 uranium-vanadium deposit is in Monument Valley, Apache County, northeastern Arizona. The uranium and vanadium minerals are in sandstone and conglomerate of late Triassic age, the Shinarump member of the Chinle formation that fills an ancient stream channel cut through the Moenkopi formation of Triassic age and the Hoskinnini tongue of the Cutler formation into the DeChelly sandstone member of the Cutler formation of Permian age.Tyuyamunite, carnotite, becquerelite, corvusite, hewettite, metahewettite, rauvite, and uraninite are the principal ore minerals. They impregnate sandstone, fill fractures, and replace quartz, clay, and fossil plant fragments.The structural features lead to the interpretation that, during the Laramide orogeny in Late Cretaceous or Early Tertiary time, movement along the bedding planes brecciated the channel-filling sediments. Resistance of the thicker channel sediments to the bedding plane slippage set up stresses that formed a zone of en echelon strike-slip vertical faults along the channel. The ore-bearing solutions may have risen along the vertical faults from a deep source, and spread out to deposit ore in the highly permeable brecciated sandstone and conglomerate. Further upward movement of the solutions would have been retarded by the lenticular, relatively impermeable clayey siltstone that overlies the ore deposit.If this hypothesis is valid, zones of en echelon strike-slip faults cutting post-Moenkopi sedimentary rocks in Monument Valley may be an indication of buried channels and of ore deposits within the channels. Additional tectonic studies in the area are recommended to test the structural interpretation.

Bleaching clay deposits, Sanders-Defiance Plateau District, Navajo country, Arizona

Bleaching clay deposits of the Sanders-Defiance Plateau district, northeastern Arizona, are an important commercial source of activated bentonite. High-grade deposits show a definite association with geologic structure, distribution of the host formation, type of parent tuff and degree of subsequent alteration, and both the pre- and post-clay erosion pattern.The district is located along the western and southern flanks of the Defiance Plateau. The DeChelly sandstone crops out in the central portion of the uplift and is successively overlain in places by the Moenkopi and Shinarump formations; the younger Chinle formation crops out in a belt around the flanks of the uplift. The Bidahochi formation of Pliocene age unconformably overlies the Chinle and older formations in the district.Accompanying the Laramide upwarping of the Defiance Plateau a broad shelf area was developed along the southwestern edge, flanked by a westward dipping monocline. The Defiance Uplift and the monocline restricted the areal distribution of the Bidahochi sediments to the shelf area. Channeling of the shelf area occurred during deposition of the lower member to the west. Volcanic ash falls occurred during deposition of the Bidahochi sediments. The ash was further accumulated in the depositional traps of the shelf area by erosion.The course of alteration of vitric tuff to bentonite is traced by field observation, microscopical examination, and x-ray analyses. The ratios of ions present in the tuff (latitic) and bentonite (calcium montmorillonite) are calculated from chemical analyses, and an equation is written for the chemical reaction between the rocks expressed in rock-cell formulas.Combination with water is the first step in the alteration. Mg has been added; and silica, Na, and K have been removed. Al is taken to have remained essentially static because it was presumably flocculated by the presence of excess divalent Ca and Mg ions.All known bleaching clay deposits of the district occur in close proximity to: (a) a belt confined to the shelf area, and (b) the approximate stratigraphic position of the medial volcanic member of the Bidahochi formation.The channel and basin structures, locale of the vitric ash accumulations, were developed as a result of regional structures. Within any depositional trap, smaller-scale structural features further controlled the accumulation of ash and subsequent-development of bleaching clays. These small-scale features may result from: (a) local squeezing, (b) inequalities of the depositional basin or channel, and (c) erosion having removed the clay since deposition and its alteration. The drainage pattern of the larger modern streams coincides somewhat with the Pliocene post-clay pattern. If by comparison the ancient channel was large, it probably removed the clay by an erosional cut-out feature.The best prospects for developing new deposits in the district lie within: (a) the areal extent of the shelf area, (b) those Bidahochi sediments immediately overlying this structural shelf in the older rocks, and (c) parent vitric ash accumulations that are latitic in composition. Favorable areas in the district are outlined.An estimated total output for the district (1924-1954) is 4,650,000 tons.

SPILITIC INTRUSION NEAR LADRON PEAK, SOCORRO COUNTY, NEW MEXICO

Research Article| September 01, 1955 SPILITIC INTRUSION NEAR LADRON PEAK, SOCORRO COUNTY, NEW MEXICO ROBERT W DUSCHATKO; ROBERT W DUSCHATKO DEPARTMENT OF GEOLOGY, COLUMBIA UNIVERSITY, N. Y. 27, N. Y. Search for other works by this author on: GSW Google Scholar ARIE POLDERVAART ARIE POLDERVAART DEPARTMENT OF GEOLOGY, COLUMBIA UNIVERSITY, N. Y. 27, N. Y. Search for other works by this author on: GSW Google Scholar Author and Article Information ROBERT W DUSCHATKO DEPARTMENT OF GEOLOGY, COLUMBIA UNIVERSITY, N. Y. 27, N. Y. ARIE POLDERVAART DEPARTMENT OF GEOLOGY, COLUMBIA UNIVERSITY, N. Y. 27, N. Y. Publisher: Geological Society of America Received: 10 May 1954 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1955, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1955) 66 (9): 1097–1108. https://doi.org/10.1130/0016-7606(1955)66[1097:SINLPS]2.0.CO;2 Article history Received: 10 May 1954 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation ROBERT W DUSCHATKO, ARIE POLDERVAART; SPILITIC INTRUSION NEAR LADRON PEAK, SOCORRO COUNTY, NEW MEXICO. GSA Bulletin 1955;; 66 (9): 1097–1108. doi: https://doi.org/10.1130/0016-7606(1955)66[1097:SINLPS]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract A suite of highly altered spilitic rocks from an intrusion 100–150 feet thick in the Yeso formation is described. There are many similar intrusions throughout the region. The alteration process is traced in detail. With falling temperatures each metallic element tends to form its own mineral or minerals with Si and Al as the only other cations. Deuteric alteration probably has been accentuated by distillation of hyperfusibles, especially sulphate radicles, from the country rocks which include much gypsum. Fine-to medium-grained albitites are the end products of differentiation, and zircon studies indicate that these rocks are partly of magmatic, partly of metasomatic origin. Five chemical analyses and results of 10 spectrographic analyses are given. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.