Bone Spring Formation Research Articles

Mississippi Valley-Type Sulfide Mineralization, Sheffield Channel, and Implications for Delaware Basin Evolution: ABSTRACT

A zinc-lead deposit of Mississippi Valley-type character occurs in the subsurface (1312 m) Sheffield channel, in basal Leonardian (Permian) dolomites along the southern Central Basin platform, Pecos County, Texas. The host dolomites represent shelf-marginal facies that pass landward into an inner shelf-carbonate/evaporite province (Lower Clear Fork), and abruptly seaward adjoining a prominent basement fault into equivalent basinal facies of the Bone Spring formation. Zoned sphalerite, accessory gypsum, and abundant pyrite are the major sulfide species present in the deposit. Sulfur isotope and fluid inclusion data, in conjunction with reconstructions of Delaware basin geothermal history, suggest that sulfide mineralization occurred during or subsequent to a burial-temperature maxima in the late Mesozoic to early Tertiary. Mineralizing fluids appear to have been derived from basinal rocks older than the Bone Spring (3355-m depths), and migrated upward along the platform bounding fault system. Sulfide precipitation at temperatures of 96/sup 0/ +/- 10/sup 0/C resulted from mixing of basinal brines and ambient host fluids that were charged with sulfur derived locally. Burial paragenesis sequentially involved a major period of pre-ore dolomitization, minor carbonate dissolution, complex sulfide-mineral emplacement, and post-ore dolomite and calcite cementation. Similar carbonate diagenetic sequences found elsewhere in the Delaware basin may bemore » evidence of a common regional hydrodynamic history of the basin.« less

Mississippi Valley-Type Sulfides in Lower Permian Dolomites, Delaware Basin, Texas: Implications for Basin Evolution

Mississippi Valley-type Pb-Zn mineralization occurs in Lower Permian (Leonardian) shelf-margin dolomites rimming an inner-shelf, carbonate-evaporite province on the southern Central Basin platform. The sulfide-hosting dolomites pass abruptly along a bounding fault system into basinal facies of the coeval Bone Spring formation. Zoned sphalerite and lesser amounts of galena and pyrite are the major sulfides present in this occurrence. Sulfur isotopes and fluid inclusions, in conjunction with considerations of the burial history of the area, suggest that Pb-Zn precipitation occurred during the late Mesozoic to Tertiary, in contact with mineralizing fluids heated to 96°-122°C (205°-252°F). These fluids were likely discharged along the Central Basin platfor from basin aquifers that are part of a regional, eastward, gravity-driven flow system that has been operative since at least the Tertiary. Sulfide precipitation appears to have resulted from mixing of basinal brines and ambient host fluids that were charged with sulfur derived from laterally contiguous shelf evaporites. Burial paragenesis of the shelf-margin host involved several episodes of eogenetic and mesogenetic dolomitization and partial dissolution (ground preparation) prior to and partly concurrent with sulfide emplacement. The occlusion of some pores by coarse-crystalline, luminescent-banded dolomite and calcite cements subsequent to mineralization is the last diagenetic event recognized in the host carbonates.

Burial Diagenesis of Allochthonous Carbonates from a Permian Slope Setting, Southeastern New Mexico: ABSTRACT

The Bone Spring formation (Permian-Leonardian) from 3-km (9,850-ft) deep conventional cores in the northern Delaware basin is a laminated, black, mixed terrigenous-carbonate mudstone with thin intervals of gray, coarse carbonate-debris flows. All carbonates have been pervasively dolomitized, and porosity and permeability were reduced to 3-8% and 1 md, respectively, during several diagenetic events related to burial history. Three dolomite generations are defined by fluorescence and cathodoluminescence microscopy and electron microprobe, and are further characterized by means of microsampling for carbon and oxygen isotopes. Over a range of 2 ^pmil (PDB), ^dgr13C decreases steadily from the first to last dolomite generation, reflecting constant mixing of rock carbon and organic carbon as hydrocarbons were evolving in the Bone Spring muds. The first dolomite generation was introduced during the time interval between early postdeposition and burial to approximately 1 km (3,280 ft). Dewatering and compaction of the Bone Spring muds accompanied matrix dolomitization, leaching of metastable grains, fracturing, and silicification of carbonate components. The mean ^dgr18O of the high-stronti m, matrix dolomite is -2.1 ± 0.4 ^pmil (PDB). A second dolomite generation may have been late Ochoan; by this time an additional 1.2 km (3,925 ft) of Guadalupian-Ochoan carbonates and evaporites had been deposited. This fluorescent, nearly stoichiometric dolomite cement has a mean ^dgr18O of -3.0 ± 0.3 ^pmil (PDB), and was coeval with hydrocarbon generation in the Bone Spring. It precipitated from fluids that interacted with the overlying evaporites. Hydrocarbon inclusions are contained in this dolomite, which is succeeded by a generation of anhydrite cement. Sulfur isotopes strongly suggest that remobilized Guadalupian anhydrite-sulfur formed this cement. The last two diagenetic phases, including the third dolomite generation, crystallized at about present burial depth. Coarsely crystalline, luminescent, pore-filling calcian dolomite, containing hydrocarbon inclusions, has a mean ^dgr18O of -5.4 ± 0.6 ^pmil (PDB). Depleted poikilotopic calcite cement (^dgr18O = -10.3 ^pmil, PDB) records the input of Tertiary water. End_of_Article - Last_Page 316------------

Some Permian (Leonardian) Radiolarians from Bone Spring Limestone, Delaware Basin, West Texas: ABSTRACT

A sample of the deep basinal Bone Spring Limestone (Leonardian) has yielded a diverse and superbly preserved assemblage of spumellarian radiolarians, associated with siliceous sponge spicules and conodonts. Radiolarians include typically Paleozoic paleoactinommids, entactiniids, and rotasphaerids; Permian albaillellids and parafollicucullids; and triradiate spongodiscids or hagiastrids. Triradiate forms, which include approximately 60% of the shells in the sample, have not previously been reported to be abundant in pre-Mesozoic rocks. Albaillellids and parafollicucullids are similar to forms reported from the Permian strata of Japan, but the Bone Spring forms do not fit in the biostratigraphic zonation proposed by Japanese workers. This may be due to gaps in the Japanese tratigraphic sections or to provincialism in radiolarian faunas. Diversity in the Bone Spring assemblage is higher than in other Permian assemblages. Most reported Permian radiolarians have been recovered by HF extraction of cherts, while the Bone Spring specimens were extracted from limestone with acetic acid. Thus, diversity differences can be partly attributed to fortuitous preservation. End_of_Article - Last_Page 444------------

Pennsylvanian and Permian Radiolarian Assemblages in Cordillera of North America: ABSTRACT

Pennsylvanian and Permian radiolarians are common constituents of the allochthonous siliceous rocks of the Cordillera of North America. Eight widely distributed Pennsylvanian and Permian radiolarian assemblages are defined for this region. These assemblages are dated by (1) joint occurrence with conodonts, as well as by (2) correlation with dated radiolarian-bearing sequences on the craton of North America. From oldest to youngest, these assemblages are: (1) Pseudoalbaillella sp. A Assemblage: In Nevada this assemblage occurs with Desmoinesian conodonts. It correlates with Desmoinesian radiolarian faunas from Oklahoma. (2) Ps. U-forma-Ps. elegans Assemblage: This assemblage occurs with late Wolfcampian conodonts in Alaska. It apparently correlates directly with the Japanese assemblage of the same name. (3) Ps. sp. B-Ps. elegans Assemblage: The biostratigraphic position of this assemblage is uncertain. It predates Ps. scalprata Assemblage and probably postdates Ps. U-forma-Ps. elegans Assemblage in the Cordillera. This assemblage cannot be correlated directly with known North American cratonal faunas or with Japanese assemblages. (4) Ps. scalprata Assemblage: This assemblage occurs with Leonardian conodonts in Nevada and Alaska. It may be equivalent to the Japanese assemblages Ps. lomentaria and/or Ps. rhombothoracata. The latter occurs with late Wolfcampian conodonts. (5) Ps. sp. aff. Ps. rhombothoracata-Ps. sp. aff. Ps. sakmaraensis: This assemblage is not independently dated in the Cordillera; it appears, however, to grade into Follicucullus scholasticus Assemblage. It may be correlative with the Ps. rhombothoracata Assemblage in Japan and with the Leonardian Bone Spring Limestone of Texas. (6) Ps. fusiformis Group Assemblage: This assemblage is younger than or equivalent to the Cordilleran Ps. sp. aff. Ps. rhombothoracata-Ps. sp. aff. Ps. sakmaraensis Assemblage. The lower part of the assemblage zone correlates well with the Leonardian Bone Springs Limestone. The most closely related Japanese assemblage is Ps. globosa Assemblage. (7) Follicucullus scholasticus Assemblage: This assemblage occurs with Wordian(?) conodonts in northern California. It is apparently correlative with the Guadalupian Lamar Limestone of Texas and with the Japanese assemblages Fo. moancanthus(?) and Fo. scholasticus. (8) Neoalbaillella Assemblage: This assemblage correlates with either Na. optima and/or Na. ornithoformis Assemblages in Japan. Elements of this assemblage overlie Wordian brachiopods and underlie Middle Triassic ammonites in Nevada. The assemblage is not known to occur on the craton of North America. End_of_Article - Last_Page 522------------

Radiolarian Succession of Latest Carboniferous through Permian, Urals and West Texas: ABSTRACT

A succession of characteristic radiolarian assemblages has been recognized through the Late Carboniferous and stratotypic Permian of the Urals and west Texas. The majority of the component taxa are yet undescribed. The oldest well-preserved assemblage from the regions appears in the lower Gzhelian Stage of the Urals and consists of more than 30 species belonging to 12 genera. Typical are large Albaillella, curled Haplodiacanthus, abundant spongy, cross-axon forms with an open central area, and Polyentactinia of octahedral form. The top of the Gzhelian Stage contains 54 species assigned to 18 genera. A new genus of the Corythoecidae, species of a highly plastic, closed spongy, cross-axon form, an unsegmented Albaillella with massive basal spines, Camptoalatus, Popofskyellu , and various triradiate, cross-axon forms are characteristic. The lower horizons of the Asselian Stage are distinguished by the appearance of Latenofistula crucex, a unique, large-pored Entactinosphaera, and spherical and elliptical forms with multiple concentric shells. Thus, radiolarian assemblages gradually change at the Carboniferous-Permian boundary. The Sarabil Suite of the Sakmarian Stage is distinguished by Haplodiacanthus perforatus (Kozur), Albaillella permica (Kozur), and large Helioentactinia. In the upper part of the Sakmarian Stage appears as assemblage of Camptoalatus monopterygius Nazarov and Rudenko, Raphidociclicus hiulcus Nazarov and Rudenko, and a new species of Ruzhencevispongus. The base of the Artinian Stage is characterized by the appearance of a new, multishelled, spongy polycystine genus possessing a three-rayed interna framework, Tormentum? pavlovi (Kozur), and a large, triradiate form with two strongly curving legs. The lower and middle parts of the Aktastinian Substage (Artinian Stage) are distinguished by an undescribed, small, discoidal, five-rayed radiolarian and by Entactinosphaera sp. The top of the Artinian Stage is typified by Haplodiacanthus anfractus, Raphidociclicus gemellus, and Ruzhencevispongus uralicus Kozur, and marks the first appearance of Follicucullus Ormiston and Babcock in the Urals. This is clearly an older horizon than that of the type species, Follicucullus ventricosus, known from the Guadalupian of west Texas. Direct comparison of radiolarian faunas indicates a correlation of the Bone Spring Limestone (Leonardian) of west Texas with the upper Sakmarian and/or Artinian Stages of the Urals. End_of_Article - Last_Page 524------------

Tectonic and Paleobiologic Significance of Permian Radiolarian Distribution in Circum-Pacific Region: ABSTRACT

The Cordillera of North American is a mosaic of allochthonous fault-founded terranes, many of which contain abundant radiolarian chert of Permian age. Permian paleolatitudes for some terranes can be reconstructed by using fusilinid, megafossil, and paleomagnetic data. Cosmopolitan Wolfcampian and older radiolarian faunas extend north as far as the Brooks Range of northern Alaska. By late Wolfcampian or early Leonardian time (Pseudoalbaillella scalprata Assemblage), a marked diversity gradient developed between tropical high diversity faunas and temperate low diversity faunas. Albaillellaria became restricted to terranes with low paleolatitudes, but radially symmetrical cross-axon radiolarians still extended into temperate paleolatitudes. The Brooks Range, Innoko, Angayuch m, and Red Paint terranes of northern and central Alaska all contain low-diversity late Wolfcampian and/or Leonardian faunas. Megafossil data indicate that these terranes may not be enormously displaced. In contrast, the Wrangellia terrane of southern Alaska, which is greatly displaced from low paleolatitudes, contains very diverse tropical Leonardian faunas. Similar faunas occur in the Golconda allochthon of Nevada and are reported from the tropical Bone Spring Limestone (Leonardian) of Texas. By Guadalupian time (Follicucullus scholasticus Assemblage), all distinctive radiolarian lineages were apparently restricted to tropical or subtropical extinctions which first affected temperate faunas during late Wolfcampian or Leonardian time, then affected subtropical or tropical faunas by late Guadalupian or post-Guadalupian time, and culminated in worldwide extinctions in latest Permian or earliest Triassic time. As the transgressive extinctions moved from temperate to tropical paleolatitudes, diverse faunas were replaced by very low-diversity entactiniid faunas and/or nondeposition. The gradual restriction of Permian radiolarian faunas records increasingly unfavorable oceanic conditions that eventually resulted in the worldwide extinction of all but the most adaptable radiolarians. End_of_Article - Last_Page 522------------

Oil Accumulations along Abo Reefing, Southeastern New Mexico: ABSTRACT

During Abo (lower Leonard) time, clastic deposition in the Delaware basin was separated from the lagoonal deposits on the Northwest shelf by a transgressive barrier reef. A lithologic study within the Abo reveals facies changes from shelf to reef to basin. Shelf, or back-reef deposits, consist of interbedded green shale and light gray to tan, fine crystalline, anhydritic dolomite. The interfingering of shelf and reef dolomites forms an effective permeability barrier to the migration of fluids back-reef. The Abo reef is a clean white to light tan, anhydritic, fine to coarse crystalline dolomite exhibiting secondary porosity development due to fracturing and solution activity. Interconnecting vertical fractures and vugs give the reef excellent reservoir characteri tics which would otherwise be absent in the tight reef matrix. Basin deposits (fore-reef) include black to dark brown argillaceous and cherty dolomites and limestones interbedded with fine-grained sandstones. Fore-reef deposits are called Bone Spring formation and are believed to be Abo equivalent. Hydrocarbons are trapped where porosity has been well developed in relatively high structural areas along the reef. At present there have been four fields discovered along the Abo reef trend in New Mexico: (1) Lovington Abo, (2) Empire Abo, (3) Corbin Abo, and (4) Turner Abo. The latter three are currently being developed. The size and reserves of these fields are dependent on the following factors: (1) thickness of reef above water, (2) structural configuration of the reef, and (3) quality of the reef pay. In the Corbin and Turner Abo fields, oil is trapped along the crest of an elongate reef ridge, one or two locations wide. The productive limits are defined by their respective water tables. The reef in Empire and Lovington is characterized by the same steep dip toward the basin (10 #176;-30°) but has a gentle slope toward the shelf; thus, the productive limits are wider (3-6 locations wide) and production is limited shelfward by an effective permeability barrier. A successful exploratory procedure has been to estimate a well's proximity to the reef crest by defining its relative stratigraphic position through correlation with areas of close control which traverse the reef. The intermediate drilling depth (4,000-8,500 feet) and high reserves (average 500,000 barrels per location) account for the acceleration of activity along the Abo reef trend. End_of_Article - Last_Page 420------------

Correlation of Permian of West Texas and Southeast New Mexico

New evidence regarding the age of the San Andres formation is presented, and it is correlated with the Cherry Canyon formation of the Delaware Mountains, the upper part of the Word formation of the Glass Mountains, and the Blaine of Texas of the Eastern shelf. The Glorieta formation of New Mexico is correlated with the upper part of the Cutoff member of the Bone Spring formation of the Delaware Mountains, the uppermost beds of the Leonard formation of the Glass Mountains, and the Holt pay of north-central Ector County, Texas. The San Angelo formation is correlated witb the upper part of the Yeso formation of New Mexico, with beds in the upper part of the Leonard formation of the Glass Mountains, and with the middle and lower parts of the Cutoff member of the Bone Spri g formation. The Grayburg formation of the subsurface is shown to be equivalent to the lower part of the Queen formation of the Guadalupe Mountains.

Relation of Permian Sedimentation to Tectonics in Guadalupe Mountain Region: ABSTRACT

Relation of Permian Sedimentation to Tectonics in Guadalupe Mountain Region: ABSTRACT

Theory of Reef Barriers: ABSTRACT

Studies of the organic reefs of the Permian basin and their relationships to rocks of contemporaneous age show a pronounced threefold facies, which the writer proposes to call the reef facies, the lagoonal facies and the facies, the latter being a new name proposed for the facies group of which the Delaware Mountain formation, the black shales of the Black Shale basin, the Bone Spring formation of the Delaware basin, and the type Leonard formation (not including the Hess facies) of the Glass Mountains are good examples. The reefs form natural barriers, separating the rocks of pontic facies from the sharply contrasted lagoonal facies which, in the Permian basin, consist of dolomitic limestones grading laterally into anhydrite and rock salt. By analogy, the reef barriers may serve as adequate explanation of the origin of all thick salt and anhydrite (or gypsum) deposits such as the New York salt and gypsum deposits, the thick salt deposits of western Colorado, the Stassfurt salt deposits of Germany, and many others. In each case we should expect a lateral gradation from the salt and gypsum (or anhydrite) into dolomitic limestone. Likewise, reef barriers may be the explanation for such contrasts as the early Paleozoic Ouachita facies (pontic facies) of the Ouachita Mountains with the contemporaneous, dominantly limestone facies (lagoonal) of the Arbuckle Mountains. In like manner, the Ordovician Marathon facies (pontic) may be separated by a reef barrier from the contemporaneous foreland (lagoonal) facies. Similarly, a reef barrier rather than a permanent land barrier may account for the contrast between deposits of the Chazy trough (lagoonal facies) and the Levis trough (pontic facies) of the Appalachian geosyncline. End_of_Article - Last_Page 1709------------

Geologic Significance of a Geothermal Gradient Curve

The Getty-Dooley well No. 7 was drilled in Eddy County, New Mexico, to a depth of 6,683 feet and passed through a thick section of Permian rocks, including the Rustler, Salado, Carlsbad, Capitan, Delaware Mountain, and into the top of the Bone Spring limestone. This stratigraphic section is divisible into three lithologic units: the Rustler-Salado, the Carlsbad-Capitan, and the Delaware Mountain unit. The subnormal geothermal-gradient curve for this well is also divisible into three parts and these subordinate gradients coincide with the lithologic divisions. Other possible factors that might cause the fundamental variations in the geothermal-gradient curve, such as water, heat reactions from solution, igneous intrusions, and radioactivity, are found wanting to explain th character of the curve. The radioactive heat of potassium is also found insufficient to affect the gradients in the Permian basin. It is therefore concluded that this subnormal geothermal-gradient curve owes its form to the different conductivities of the successive layers of rock.