Abo Formation Research Articles

Paleoclimatic Controls on Stable Oxygen and Carbon Isotopes in Caliche of the Abo Formation (Permian), South-Central New Mexico, U.S.A.

ABSTRACT The stable oxygen and carbon isotopic composition of caliche in fluvial and supratidal rocks of the Abo Formation (Permian), south-central New Mexico, is controlled by paleoclimate and depositional environment. Fluvial caliche consists of low-Mg calcite nodules and vertically oriented tubules that display stage II texture. Micrite matrix support, brecciation, ooids/pisoliths, aveolar-septal texture, and peloids are common in the fluvial caliche and, along with red color and slickensides in the host shale, indicate pedogenesis in a well-oxidized vadose zone. In contrast, periodic waterlogging of the supratidal paleosols, probably due to high water table, is indicated by drab colors, carbonaceous flecks, horizontal rhizoliths, and the paucity of vadose textures in the stage II caliche n dules. Stable oxygen isotopes are similar in the fluvial and supratidal caliches and range from 21.6 to 30.5 (SMOW). The data exhibit a crude bimodality and 18O enrichment with a decrease in age (higher in the section). Consideration of these data in the context or -temperature relations suggests that 1) surface waters responsible for caliche formation increased in 18O (from roughly -8 to + 1) over the 18 m.y. time interval that separated the lowest stratigraphic nodule horizon from the highest, 2) the inc easing 18O values also reflect a warming trend (approximately 15° to nearly 3°C) in the mean monthly temperature over this same time period, with perhaps an associated increase in Permian ocean temperatures, and 3) the significant variation in 18O from oldest to youngest caliche was probably enhanced by the effect, such that as the temperature increased, the amount of precipitation decreased, resulting in high 18O values. Caliches in the Abo are enriched in heavy carbon (-7.2 to -1.5 PDB) compared to that of soil carbonate derived exclusively from C, plants (-12 PDB), and the supratidal caliches contain somewhat heavier carbon compared to the fluvial caliche. The 13C values for both environments increase with a decrease in caliche age. These results indicate that as the temperature increased and rainfall decreased with time, the level of C3 plant productivity apparently declined, allowing a greater influx of atmospheric CO2 into the soil. This can only occur when soil respiration rates are quite low or at very sha low depths (less than 10 cm), or both. Atmospheric CO2 seems to have invaded the supratidal soils to a somewhat greater extent than the fluvial soils.

Tectonic and Eustatic Controls on the Carbonate Stratigraphy of the Leonardian-Guadalupian (Permian) Section, Northwestern Delaware Basin, New Mexico and Texas: ABSTRACT

The effects of tectonics and eustasy on carbonate sedimentation have been determined using seismic, well logs, and outcrop data for the middle Permian of the Delaware basin. Sequence and chronostratigraphic analyses indicate the section contains a broad, tectonically controlled aggradational/progradational cycle overprinted by eustatic sea level cycles. Early Leonardian deposition of the Abo Formation and the third Bone Spring sand occurred during a period of rapid subsidence, producing the aggradational geometry observed on seismic and well logs. This followed a time of uplift to the northwest of the study area, which caused enhanced shelf erosion during the late Wolfcampian. The aggradational style of deposition continued through the middle Leonardian. Late Leonardian time is characterized by progradational geometry, due to a slower subsidence rate. This resulted in a 15-km progradation of the Bone Spring shelf margin in the northwestern part of the Delaware basin. A second period of uplift to the northwest followed, leading to the deposition of the sands of the Brushy Canyon Formation (Guadalupian). This aggradational/progradational cycle is followed by a similar cycle which ends after the deposition of the Capitan Formation. Within the carbonate-dominated Leonardian aggradational/progradational cycle, nine sea level cycles are recognized. The lowstand systems tracts withinmore » this package are of two types. The lowstands within the aggradational part of the section consist primarily of slope fans, while those associated with progradation contain large lowstand prograding wedges. Steep margins are associated with aggradation, while progradation is characterized by a ramplike geometry. Highstands are widespread on the shelf and prograde into the basin throughout this interval.« less

New Interpretations of Pennsylvanian and Permian Stratigraphy, San Juan Basin and Southeast Paradox Basin: ABSTRACT

The Honaker Trail, Paradox, and Pinkerton Trail Formations of the Hermosa Group are recognized throughout most of the San Juan basin. The Paradox Formation is extended southeastward beyond the limits of its evaporite facies into the basin, where it consists of thick shelf-carbonate rocks and thin black shale, sandstone, and siltstone interbeds. Where the Hermosa Group thins onto the marginal uplifts, the Paradox loses the thick carbonate rocks and becomes indistinguishable from the rest of the Hermosa. The Hermosa is correlated in the subsurface with the Madera and Sandia Formations to the southeast. The transitional Rico Formation, between the marine Hermosa Group and the continental Cutler Formation, is identified throughout the subsurface of the San Juan basin and is correlated with similar deposits out-cropping along the northern and eastern margins. The Cutler Formation includes the Organ Rock, Cedar Mesa, and Halgaito members throughout most of the basin. In the vicinity of the Hogback monocline, the Cedar Mesa Sandstone Member undergoes a gradational eastward facies change from cyclic evaporite and sandstone to thick-bedded sandstone. The subsurface Cedar Mesa is correlated in part with similar rocks in the outcropping Abo and Supai Formations.

Enhancing Geological Description of a Naturally Fractured Reservoir via Drawdown Testing: ABSTRACT

The Pecos Slope Abo gas field is located on the northwestern edge of the Northwestern shelf of the Permian basin. The 600-mi{sup 2} field was designated a tight gas formation during 1981 and 1982, which resulted in approximately 800 wells drilled through 1988. The tight gas designation required documenting core, production, and transient pressure test information. Pressure was equal throughout the reservoir, which resulted in normal hydrostatic reservoir pressure on the west side. However, the east side of the reservoir, which is 2,000 ft downdip, is under-pressured. A review of this information suggests that this formation, with lenticular sands, is a naturally fractured reservoir. Internal reservoir geometry, best described by the depositional environment, determines recovery efficiency. for example, the wave-dominated Woodbine Formation of the East Texas field has a very high recovery efficiency. In contrast, complex geometries such as fluvial-dominated deltaic reservoirs have lower recoveries due to poor facies continuity. The lenticular Pecos Slope Abo formation falls in the fluvial category or depositional environments. The Pecos Slope Abo gas field has been producing for six years. During this time, daily production rates and flowing wellhead pressures have been recorded for more than 200 wells (half million data points). This productionmore » information was treated as a long-term pressure drawdown test and was analyzed using a naturally fractured reservoir analytical technique. The descriptors resulting from the analyses are correlated with performance to arrive at an enhanced characterization of the internal reservoir geometry which will be useful when evaluating infill drilling opportunities.« less

Paleomagnetism and rock magnetism of Quaternary volcanic rocks and Late Paleozoic strata, VC‐1 core hole, Valles Caldera, New Mexico, with emphasis on remagnetization of Late Paleozoic strata

Paleomagnetic and rock magnetic data obtained from azimuthally unoriented core samples, collected at approximately 1‐ to 3‐m intervals, of Continental Scientific Drilling Program core hole VC‐1 have prompted reinterpretations of the Quaternary volcanic stratigraphy intersected by the bore and have aided in evaluating the thermal regime within late Paleozoic strata attending fluid circulation and mineral deposition during and after development of the Toledo and Valles calderas. The results from Quaternary units (Banco Bonito Obsidian: I = +35.4°, a95 = 2.8° (inclination only determinations), n = 33; Battleship Rock Tuff: D = 359.6°, I = +42.4°, a95 = 2.8°, n = 5 site means (surface sites); VC‐1 Rhyolite: I = +39.2°, a95 = 12.8°, n = 7; Upper VC‐1 Tuff: I = +37.2°, a95 = 10.7°, n = 13; Middle VC‐1 Tuff: I = +42.1°, a95 = 2.1°, n = 39; South Mountain Rhyolite: D = 350.9°, I = +49.9°, a95 = 3.4°, n = 10 (one surface site)) are consistent with isotopic age data, indicating that the entire moat volcanic sequence intersected is less than 650 kyr. Monitoring of natural remanent magnetization (NRM) intensity, NRM directions, directions of magnetizations isolated during progressive demagnetization, median destructive forces, and rock magnetization parameters has identified systematic variations within the thick Banco Bonito Obsidian and VC‐1 Tuff units. The Permian Abo Formation, Pennsylvanian to earliest Permian Madera Limestone, and Pennsylvanian Sandia Formation typically contain a moderate positive inclination magnetization component (Abo Formation: I = +52.2°, a95 = 7.4°, n = 16; Madera Limestone: I = +58.4°, a95 = 2.8°, n = 105; Sandia Formation: I = +53.9°, a95 = 4.8°, n = 21); when residing in magnetite, it is usually unblocked in the laboratory by 350°C; when carried by hematite it is unblocked by 550°C. A moderate negative inclination (e.g., Madera and Abo strata: D = 173.1°, I = −46.6°, a95 = 5.5°; n = 47 samples; assuming a north seeking positive inclination RM providing a useful means of core orientation), oppositely directed magnetization is occasionally isolated and removed at higher laboratory unblocking temperatures (up to 550°C in magnetite‐dominated and 600°C in hematite‐dominated lithologies). Where present, magnetizations of shallower inclination (e.g., Madera and Abo strata: D = 160.1°, I = −10.9°, a95 = 4.4°, n = 28) are removed over higher ranges of unblocking temperatures, and these are probably of late Paleozoic age. The moderate negative and positive inclination magnetizations are in all likelihood viscous partial thermoremanent magnetizations (TRMs) (VPTRMs). These were activated at moderate (∼300°C) temperatures between 1.45 and 0.97 Ma, attending and following the main stages of Toledo/Valles caldera development during the Matuyama, and at near‐present downhole temperatures (∼100°–180+ °C) during the Brunhes and possibly within the last 10 kyr, respectively. Importantly, the preservation of negative inclination RM components in magnetite‐dominated lithologies of the Madera Limestone dictates that temperatures during the Brunhes chron (past 730 kyr) did not exceed approximately 300°–350°C. The inferred temperatures for thermal activation of the VPTRMs, based upon the Middleton and Schmidt thermal activation curves for both magnetite and hematite derived following Walton, agree with independent estimates of thermal activity, using fluid inclusion and K‐Ar isotopic age determination data, during the Quaternary. The results further illustrate the potential usefulness of thermal activation theories for inferring temperatures of past geologic events, especially when they can be applied to magnetizations of similar age residing in both magnetite and hematite, and of paleomagnetic and rock magnetic studies in general in continuous coreholes in complex geologic environments.

Alteration in the Madera limestone and Sandia formation from core hole VC‐1 Valles Caldera, New Mexico

Core hole VC‐1 penetrated the southwestern ring fracture zone of the 1.1 Ma Valles caldera and at a depth of 333 m intersected the top of the Paleozoic section including the Abo Formation, Madera Limestone, and Sandia Formation, reaching a total depth of 856 m. The Paleozoic rocks, which consist of thin‐bedded limestone, siltstone, mudstone, sandstone, and local conglomerate, are overlain by volcanic rocks of the caldera moat that are less than 0.6 Ma. Diagenetic and at least three hydrothermal alteration stages were identified in the Madera Limestone and Sandia Formation. Diagenetic clay alteration was pervasive throughout the sedimentary rocks. Volcanic activity at 16.5 Ma and continuing through the formation of the Valles caldera resulted in high thermal gradients, which caused recrystallization of diagenetic clay minerals. Interstratified smectite‐illite is the most diagnostic clay mineral throughout the section; structurally, the illite component in the ordered interstratified illite‐smectite changes gradationally from 70% at the top of the Madera Limestone to 95% at the base of the section in the Sandia Formation. Pyrite that occurs as small clots and lenses as well as finely disseminated is interpreted as being of diagenetic origin, especially in organic‐rich beds. Low permeability of much of the Paleozoic section precluded the deposition of hydrothermal minerals except in fractures and intergranular space in some of the more permeable sandstone and brecciated horizons. Three stages of hydrothermal mineral deposition are defined. Stage I is widespread and includes mainly chlorite, calcite, pyrite, and interstratified smectite‐illite that was formed prior to caldera development at temperatures approximating 200°C. Stage II is characterized by quartz, sericite, and scarce sulfides deposited locally by fluids at approximately 275°C shortly before or at the time of early caldera‐related volcanism. The Stage III hydrothermal event, associated with formation of the Valles caldera, caused complex brecciation accompanied by deposition of phengite and molybdenite at temperatures locally approaching 300°C mostly in rocks underlying the Madera Limestone. During the present drilling program, thermal aquifers were encountered at 483 m (113°C), 533 m (125°C), and 845 m (184°C), very close to the Stage II and III mineralized zones; however, measured temperatures of the present hydrothermal system are much lower than during the main hydrothermal events. Good permeability has been maintained in these three levels for a long time while the rest of the Madera Limestone and Sandia Formation was sealed by hydrothermal mineral precipitation.

Paleomagnetism of the Late PEnnsylvanian and Permian: A test of the rotation of the Colorado Plateau

Coeval formations on both the North American craton and the Colorado Plateau have been sampled for the comparison of paleomagnetic pole positions. The latest Pennsylvanian‐earliest Permian Laborcita and the Early Permian Abo formations of eastern New Mexico, and the latest Pennsylvahian Wescogame Formation of the Supai Group of northwestern Arizona were studied. Thermal demagnetization demonstrated that the majority of the samples in all three formations were remarkably free of significant secondary overprinting. Computation of pole positions used only samples which exhibited univectorial decay to the origin over at least three or more temperature steps. The paleopole of the Wescogame Formation is 119.2°E, 47.3°N (N=45 samples, k=41.6, dp=1.7, and dm=3.4); the Laborcita Formation paeopole is 130.6°E, 41.8°N (N=114 samples, k=42.9, dp=1.0, and dm=2.0); and the overlying Abo Formation paleopole is 118.3°E, 49.7°N (N=84 samples, k=54.9, dp=l.l, and dm=2.1). Comparison of the Wescogame, Laborcita, Abo and other paleopoles of this age shows the plateau poles displaced clockwise, confirming a clockwise rotation of the Colorado Plateau with respect to stable North America. The new data could be interpreted to indicate a 7°±4° rotation of the plateau; however, the direction of displacement of Pennsylvanian and Permian paleopoles is significantly different from that exhibited by the Early and the Late Triassic poles. The current body of data is best fit by not one, but two, rotations and suggests that the Colorado Plateau rotated in Late Permian time, prior to a later, presumably Laramide, rotation. Separate calculations of the Late Permian rotation, from Late Pennsylvanian data and from Early Permian data, both indicate a rotation of about 9.5°±2.7° northward and 5.4°±2.7° westward. This study thus suggests that at least two rotations of the Colorado Plateau have occurred prior to the most recent rotation involving the opening of the Rio Grande Rift. This history of rotations implies a quasi‐independent plate motion behavior for the Colorado Plateau microplate.

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.

Siliciclastic-Carbonate Interactions in Laborcita Formation, Sacramento Mountains, New Mexico: ABSTRACT

Outcrop exposures of the Laborcita Formation (Wolfcampian) reveal an active depositional environment with abrupt lateral and vertical changes between fan-deltaic and carbonate sediments. The siliciclastic source area was to the east, in the Pedernal uplift. Fan-delta lobe shifting was important in producing the cyclic nature of deposition. Away from the area affected by the fan-deltas, deposits are increasingly calcareous. Shales are the predominant lithology in the Laborcita Formation, due to the abundance of carbonate-inhibiting terrigenous matter, especially in restricted areas. A few digitate stromatolites and Archeolithophyllum sp. mounds indicate subaerial exposure. Toward the edge of the narrow shelf, large phylloid-algal buildups (20 m or 65 ft thick) occur. An exposure in Coyote Canyon, near the northern end of the Laborcita exposure, shows an onlapping sequence of several mounds. This mound zone was terminated when muds and fine to medium-grained terrigenous sands migrated in and inhibited growth of the carbonate-producing organisms. The terrigenous sediments were in turn overlain by grainstones exhibiting lon , low-angle (15°) cross-bedding, which dips landward (southeast). Individual grainstone beds are thin (0.5-1.5 m or 1.6-5 ft), extend along strike laterally for about 2.5 mi (4 km), and are composed largely of bioclastic carbonate grains (not oolitically coated) with 5% quartz grains. Direction of migration was southwest to northeast. Gradual emergence is recorded by the Laborcita Formation. With continual progradation of terrigenous deposits, interrupted by marine incursions resulting in deposition of shallow-water carbonated deposits, the transitional Laborcita Formation was ultimately overlain by the terrigenous Abo Formation. End_of_Article - Last_Page 256------------

Transitions in a Fluvial System--Abo Formation, Southeastern Nacimiento Mountains, New Mexico: ABSTRACT

The Abo Formation (Wolfcampian) in the southeastern Nacimiento Mountains, New Mexico, is an alluvial plain red-bed sequence which records the evolution of a fluvial system within the distal reaches of a large clastic wedge. Sediment was derived from the southern Uncompahgre uplift, with a paleoflow to the southwest. The Abo Formation consists of mudstone, feldspathic sandstone, and intraformational conglomerate. Three major lithofacies associations, representing distinct fluvial depositional settings, may be distinguished. The lowermost division (Unit A) (100+ m, or 330+ ft, thick) is mudstone dominant with isolated sandstone bodies showing cutbanks and lateral accretion surfaces. Ridge-and-swale features were noted on an exhumed point bar surface. The sandstones commonly show a progressive upward decrease in the scale of internal bedforms with a lower scour surface containing intraformational conglomerate. Trough cross-bedding is the dominant bedform in the sandstones with common planar-tabular and flat-bedded interbeds. The uppermost sandstones, characteristic of levee and crevasse-splay sands, are ripple cross-bedded with abundant bioturbation and some plant roots. The overbank mudstones contain numerous pedogenic horizons characterized by calcrete nodules (representative of all stages of evolution), vein networks, pseudo-anticlinal structures, slickensides, color mottling, and bioturbation. Vertebrate remains are found in the mudstones. The middle division (Unit B) (approximately 70 m, or 230 ft, thick) is characterized by thick multilateral channel sandstones and thinner mudstones. The sandstones are coarse grained and contain common intraformational conglomerate. Large-scale trough cross-stratification is the dominant bedform. Pedogenic horizons are present but less common than in unit A. The uppermost division (Unit C) (approximately 30 m, or 100 ft, thick) is entirely composed of reddish-orange, very fine-grained sandstone. Flat bedding is the dominant bedform. High aggradation is indicated by abundant dish structures in the sandstones and aggradational ripple cross-bedding. Mudstone is rare and preserved as thin laminae. End_Page 466------------------------------ The fluvial sequence from Unit A to Unit B is thought to represent the transition from a fine-grained to a coarse-grained meander-belt system. The transition to Unit C reflects a change to flash-flood, ephemeral-stream controlled sedimentation. Allocyclic phenomena are suggested as probably cause of these fluvial transitions. End_of_Article - Last_Page 467------------

Geology of Abo Gas-Producing Areas of Pecos Slope, Chaves County, New Mexico: ABSTRACT

The discovery of Abo gas production from continental Permian red beds in north-central Chaves County, New Mexico, resulted in a flurry of drilling activity. Yates Petroleum Corp. reentered the Honolulu 1 McConkey, an Ellenburger dry hole, and completed it from Abo perforations for an initial potential of 2,551 mcf of gas per day and 1 bbl of condensate per day. Although this discovery was completed in September 1977, drilling continued at a slow pace until federal regulations designated the Abo formation as tight gas sands, in 1980. This stimulated drilling activity to the extent that, as of August 1983, almost 850 wells had been drilled, with a high success ratio. Lee named the Abo formation for sandstone exposures in Abo Canyon, at the south end of the Manzano Mountains, southeast of Albuquerque. Needham and Bates re-described the Abo and named a type section for exposures in Socorro and Torrance Counties and considered it to be of continental origin because of cross-bedding, plant remains, and other characteristics. The Abo is generally believed to be Wolfcampian in age; however, in a few areas the upper portion of the Abo is Leonardian. This is based partly on fossils and also on the fact that the Abo in places grades into the overlying Yeso. The Pedernal landmass, situated to the north and west of the Pecos slope area, provided most of the sediments as siltstones, sandstones, mudstones, and shales. The sandstones are characteristically arkosic in most areas. These Abo sediments were deposited under fluvial-deltaic conditions. End_of_Article - Last_Page 119------------

Fan-Deltaic and Marine Siliclastic Facies of Laborcita Formation, Northern Sacramento Mountains, New Mexico: ABSTRACT

Fan-deltaic sequences in the Laborcita Formation, northern Sacramento Mountains, New Mexico, form a clastic wedge that prograded north and west. These Penn-Permian (Virgilian-Wolfcampian) deposits represent a facies tract of proximal to distal alluvial fan and fan-deltaic facies. Associated nearshore and shelf siliclastics are also developed. Red bed conglomerates interpreted as braided and ephemeral fluvial channel fills are the most proximal deposits. These limestone cobble conglomerates crop out near the Fresnal Canyon fault and are syntectonic deposits. Northern quartzite cobble conglomerates are less proximal and form more continuous sheet-like units. These thick (10 m, 33 ft) and laterally extensive (6 km, 4 mi) conglomerates that contain trough cross-bedded coarse sand lenses associated with intrachannel bars are interpreted as midfan deposits. Shales and thin (20-40 cm, 8-16 in.) progradational distal sands under conglomerates are highly variable in total thickness (20-60 m, 65-200 ft). The thin sandstones show evidence of marine processes and are interpreted as fan-deltaic foreset deposits. Gray limestone and chert conglomerates deposited directly on limestones are thin (0.5-2 m, 1.5-6.5 ft), deposited subaqueously, and exhibit reworking by marine processes. Northern sands are disassociated with conglomerates. These green arkosic sands are relatively thick (3 m, 10 ft) and contain landward (east) accreting tangential foresets. Geometry, stratigraphic position, and minor upward coarsening indicate shelf-bar deposition. Fan-delta source areas shifting during Laborcita deposition. Initial deposits were from the southeast and characterized by limestone/chert conglomerates. Later quartzite/rhyolite porphyry cobble conglomerates prograded from the east and northeast. Ultimately, alluvial fan red beds of the Abo Formation prograded over Laborcita fan-delta and shelf-bar deposits. End_of_Article - Last_Page 512------------

Exploration Geology and Depositional Modeling of a Continental Tight Sand Reservoir, Abo Formation, Chaves County, New Mexico: ABSTRACT

The Wolfcampian-Leonardian age Abo Formation has been the major objective of exploration efforts in southeastern New Mexico since 1980. The Abo Formation in Chavez County consists of red and green mudstones and shales interbedded with very fine-grained reddish-orange sandstones. The sandstones are subarkosic arenites deposited in a fluvial/delta plain environment on the northwest shelf of the Permian basin. Producing sandstones are characterized by very low in-situ permeabilities (0.006 to 0.01 md) and porosities (determined from CNL density logs) ranging from 5 to 12%. Petrographic analysis of the producing zones yields only traces of visible porosity (^approx 1%), indicating the relative importance of fractures to total porosity. The importance of this secondary porosit is substantiated by the concentration of production within an area of major southwest-northeast-trending buckles that result in folded and fractured zones parallel to their strike. Abo sediments were derived from the predominantly granitic Pedernal uplift to the north and west of the producing area. The prograding fluvial/delta plain is evidenced by calcareous mudstones at the base of the Abo with calcite fracture fillings grading upward into anhydritic mudstones containing anhydrite fracture fillings and bird's-eye lenses. In general, three main producing zones are found in the upper Abo Formation. These sandstones occur either as a single thick (6 to 10 m, 20 to 33 ft) sand or several thin (2 to 4 m, 6.5 to 13 ft) sands separated by thin mudstones. Changes in thickness and character o these three major sands represent lateral shifts in subaerially deposited, braided paleochannels. The relatively homogenous mudstone intervals between producing sands and at the base of the section represent delta switching and tidal backreef (submarine) deposition. Gas wells in the Abo initially produce from 200 to 4,000 MCFGPD of dry (1,000 Btu) gas after considerable acidizing and fracturing. The modeling of the depositional environment of the Abo is critical to the selection of prime drilling locations. Paleochannel development and trends, as well as significant interbedded mudstone intervals, are essential for good Abo potential. Several stratigraphic and diagenetic trapping processes may result in hydrocarbon accumulations within these anastomosed fluvial sandstones. Channel fills are most commonly contained laterally and vertically by mudstones. Differing amounts of calcite and anhydrite cement and argillaceous matrix within the sandstones may create diagenetic traps within the channels. The best Abo wells are located in areas where paleoc annels are well developed and intersect southwest-northeast-trending structural zones. The completion of these wells can be complicated by inadequate cementing prior to fracturing resulting in the fracturing of containing mudstones and shales instead of gas-bearing perforated sandstone intervals. The relatively shallow, 950 to 1,300 m (3,100 to 4,300 ft), depths to encounter pay, combined with the higher allowable tight gas (107) price in the Abo, have stimulated significant activity in this new play that is certain to expand as the reservoir and trapping mechanism is better understood. End_of_Article - Last_Page 476------------

Evolution of a Fluvial Clastic Wedge, Abo Formation (Wolfcampian), Sacramento Mountains, New Mexico: ABSTRACT

Outcrops of the Abo Formation (Wolfcampian) in the northern and central Sacramento Mountains of south-central New Mexico record the evolution of fluvial systems within a major clastic wedge. This wedge was derived from the Pedernal uplift and prograded westward into the Orogrande basin. Regionally, the Abo Formation thickens from 60 m (197 ft) in the central Sacramentos, to over 545 m (1,788 ft) in the northern portion of the range, a distance of approximately 29 km (18 mi). Superposed on the regional pattern are local thickness variations of up to 91 m (300 ft). These occur within distances as small as 0.4 km (0.25 mi), and represent local tectonic and paleotopographic controls on sedimentation. Clast-supported cobble conglomerates, associated with laminated mudstones and discontinuous coarse arkosic sandstones, are present near the base of the Abo Formation. The conglomerate lenses range from 0.5 to 20 m (1.5 to 66 ft) thick, and from 15 m (49 ft) to several kilometers wide. They exhibit poor stratification, occasional clast imbrication, and near horizontal to concave-upward erosional bounding surfaces. Locally, nodular CaCO3 occurs in beds or scattered throughout the associated mudstones. The central portion of the sequence is characterized by abundant conglomeratic medium to very coarse-grained arkosic sandstone lenses interbedded with laminated mudstones. These lenses range from 0.25 to 10 m (0.8 to 33 ft) in thickness, and 10 to 110 m (33 to 361 ft) in width. Commonly, several lenses will coalesce, forming laterally extensive belts. Both erosional and depositional (lateral accretion) bounding surfaces are well developed within individual lenses. Low-angle, large-scale trough cross-bedding is the dominant stratification type within these units, however, small to large-scale tabular foresets occur, as do planar, ripple, and small-scale trough stratification. Occasionally, individual units fine upward in grain size and/or scale of structures. This sandstone-rich horizo varies laterally in thickness, and grades upward into a mudstone-rich horizon at the top of the Abo Formation. The upper interval of the Abo sequence contains infrequent fine to coarse-grained arkose lenses enclosed in laterally extensive red mudstones. Paleosols and caliche horizons are present, but not common, in the mudstones. The basal conglomeratic horizon of the clastic wedge represents braided stream deposition at the distal end of arid alluvial fans associated with the tectonically active Pedernal uplift. Caliche and paleosols developed in the overbank mud drapes and levees of these deposits. The conglomerates grade into arkosic sandstones, reflecting the intense weathering and erosion of the granitic core of the uplift. The multilateral sandstone lenses characteristic of the mid portion of the Abo Formation were deposited in low-sinuosity, coarse-grained (bed-load) meander belts; however, higher sinuosity, mixed-load channel and crevasse splay deposits also occur locally. Finally, as the Pedernal source area was buried by its own debris, thick, broad flood-plain deposition predominated. Sandstones ass ciated with the red mudstones were deposited in shallow ephemeral channels and crevasse splays. End_of_Article - Last_Page 550------------

A new species of Trimerorhachis (Amphibia, Temnospondyli) from the Lower Permian Abo Formation of New Mexico, with discussion of Permian faunal distributions in that state

A new species of Trimerorhachis (Amphibia, Temnospondyli) from the Lower Permian Abo Formation of New Mexico, with discussion of Permian faunal distributions in that state

Primary Sedimentary Structures of Abo Formation (Permian) near Albuquerque, New Mexico: ABSTRACT

Primary Sedimentary Structures of Abo Formation (Permian) near Albuquerque, New Mexico: ABSTRACT

Paleocurrents and Provenance of Abo Formation in Central New Mexico: ABSTRACT

Paleocurrents and Provenance of Abo Formation in Central New Mexico: ABSTRACT

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.

Permian type sections in central New Mexico

Research Article| November 01, 1943 Permian type sections in central New Mexico C. E. NEEDHAM; C. E. NEEDHAM Search for other works by this author on: GSW Google Scholar ROBERT L. BATES ROBERT L. BATES Search for other works by this author on: GSW Google Scholar GSA Bulletin (1943) 54 (11): 1653–1668. https://doi.org/10.1130/GSAB-54-1653 Article history received: 08 Feb 1943 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation C. E. NEEDHAM, ROBERT L. BATES; Permian type sections in central New Mexico. GSA Bulletin 1943;; 54 (11): 1653–1668. doi: https://doi.org/10.1130/GSAB-54-1653 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Standard usage has established four Permian formations in central New Mexico above a thin unnamed basal Permian limestone. In ascending order these are: the Abo formation — type locality in Abo Canyon, Valencia and Torrance counties, New Mexico; Yeso formation — type locality near Mesa del Yeso, Socorro County; Glorieta sandstone — type locality in Glorieta Mesa, San Miguel County; and San Andres limestone — type locality in Rhodes Canyon, San Andres Mountains, Socorro County. The type sections for these formations have never been adequately designated, and the formations at the type localities have not been sufficiently delimited and described. This paper attempts to designate the type section, define the limits, and describe the characteristic lithology of each formation at its type locality. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not currently have access to this article.

The Pennsylvania-Permian Contact in New Mexico: ABSTRACT

The Pennsylvania-Permian contact in New Mexico has generally been recorded as being between the marine Pennsylvanian Magdalena and the non-marine Permian Abo formation. Evidence is presented in this discussion to show that two unconformities of large magnitudes, with intervening marine deposits, are present between the Pennsylvanian Magdalena and the Permian Abo formation in many areas of New Mexico. One of these unconformities is at the base of the Abo formation and the other occurs lower in the section. Furthermore, evidence is presented to show that the lower of these two unconformities marks a contact between fusulinid-bearing marine Pennsylvanian and fusulinid-bearing marine Permian sediments. In extreme northern New Mexico, the Pennsylvanian- ermian contact seems to be between marine Des Moines Pennsylvanian sediments and non-marine Permian redbeds. End_of_Article - Last_Page 907------------