Search USGS⌕ Search

Geology topics

R.W. Stanton

Publications and source records attributed to R.W. Stanton.

At least 19 recordsLinked to original sources
USGS1995

Comparison of the petrography, palynology, and paleobotany of the Little Fire Creek coal bed, southwestern Virginia, U.S.A.

Two continuous cores that penetrated the Lower Pennsylvanian Little Fire Creek coal bed in the Southwestern coal field in southwestern Virginia were sampled and X-ray radiographed to determine subunit distinctions. Comparison of petrographic, palynologic, and paleobotanic data from the same sample sets from the two cores allowed for comparison of compositional data within the Little Fire Creek coal bed. The proximate, petrographic, palynologic, and plant tissue data from two sets of samples indicate a high ash, gelocollinite- and liptinite-rich coal consisting of a relatively diverse paleoflora, including lycopsid trees, small lycopsids, tree ferns, small ferns, pteridosperms (seed ferns), and rare calamites and cordaites. The relatively very high ash yields (3–80 wt%), the relatively thin subunits (1–28 cm), and the large scale vertical variations in palynomorph floras suggest that the study area was at the edge of the paleopea-forming environment. As a result, most of the compositional correspondences are among those components indicative of degradation or decomposition.

Virginia↗
USGS1994

Isotopic evidence for the source of sulfur in the Upper Freeport coal bed (west-central Pennsylvania, U.S.A.)

Sulfur isotopic variations were used to determine the sources of sulfur in a medium-sulfur coal (???2 wt%S) that lacked marine influence, which is often cited as a major source of sulfur in coal. Variations in the amount and isotopic composition of the organic and pyritic sulfur among the coal-bed facies of the Upper Freeport coal bed (Middle Pennsylvanian) are attributed to differential incorporation of syngenetic and epigenetic sulfur. These variations reflect varying environmental conditions during paleopeat formation, porosity and permeability, and the availability of sulfate and iron. A large increase in the abundance and sulfur isotopic value of pyritic sulfur in the upper facies of the coal bed, in proximity to the overlying lacustrine shale, corresponds to an increase in massive and irregular forms of pyrite. This relationship is attributed to at least two stages of epigenetic pyrite incorporation. An early stage of epigenetic pyrite, moderately enriched in 34S, apparently formed during the fluvial-lacustrine period immediately following peat accumulation. A late stage of epigenetic pyrite, highly enriched in 34S, formed after compaction of the original peat as cleat- and fracture-filling pyrite; this sulfur was probably derived from bacterial reduction of dissolved sulfate in groundwater. Isotopic mass-balance calculations indicate that this late-stage epigenetic pyrite may account for up to ???50% of the pyritic sulfur in some upper facies of the coal bed. These results suggest that most of the pyritic sulfur in the Upper Freeport coal bed may be epigenetic, incorporated either soon after peat accumulation or later during coalification. ?? 1994.

Chemical Geology↗
USGS1993

Comparison of the petrography, palynology and paleobotany of the Stockton coal bed, West Virginia and implications for paleoenvironmental interpretations

The Stockton coal bed (Middle Pennsylvanian) is a relatively high ash coal composed primarily of moderately thin banded, sparsely thin banded, and nonbanded coal (splint and cannel coal). Comparisons of petrographic, palynologic, and paleobotanic data gathered from the same sample sets from a single column of the Stockton coal bed indicate that compositional correspondences among the sets exist regardless of coal type. Some correspondences are believed to exist because of original plant constituents and others because of the paleoenvironment of peat formation. Using some combination of these data is critical when interpreting paleoenvironmental conditions because (1) a direct correspondence is lacking between many of the data and (2) each of the three data sets provides a unique and important perspective on the paleomire. The Stockton paleomire in the area of this study supported a diverse flora that consisted of both small and arboreous lycopsids, small ferns and tree ferns, calamites, cordaites, and pteridosperms. There appear to have been two successions of Lycospora spore-dominated, vitrinite-rich, liptinite-poor peat formation, which were followed by inertinite-rich peat formation marked by a tree fern-dominant spore assemblage and abundant unidentifiable plant tissues. These are interpreted to be two water-laden or topogenous peat formational stages followed by slightly domed, better drained peat formation.

West Virginia↗
USGS1993

Factors affecting the geochemistry of a thick, subbituminous coal bed in the Powder River Basin: Volcanic, detrital, and peat-forming processes

The inorganic geochemistry and mineralogy of three cores from the Anderson-Dietz 1 coal bed, a 15.2-m-thick subbituminous coal bed in the Tongue River Member (Paleocene) of the Fort Union Formation, were examined (1) to determine if the cores could be correlated by geochemical composition alone over a total distance of 2 km and (2) to identify the major factors that influenced the geochemistry of the coal bed. Chemical data (46 elements on a coal-ash basis) for 81 coal samples and 4 carbonaceous rock samples, with most samples representing a 0.6-m-thick (2-ft) interval of core, were grouped into compositional clusters by means of cluster analysis. Seven major clusters were produced; two of these clusters can be used to correlate the coal bed throughout the study area. Data from scanning electron and optical microscope analyses indicate that several factors influenced the geochemistry of the Anderson-Dietz 1 coal bed. The majority of mineral grains in the coal bed are interpreted to be detrital (water borne); evidence includes the presence of rounded to subrounded quartz grains having two-phase, aqueous fluid inclusions characteristic of hydrothermal or low-to-moderate grade metamorphic quartz. These quartz grains are found throughout the coal bed but are most abundant in samples from the midpart of the bed, which was influenced by detrital input associated with the deposition of the clastic rocks that form the split between the Anderson and Dietz 1 coal beds 900 m to the east of the study area. In addition to the detrital minerals mentioned above, volcanic ash that was fluvially transported to the sites of peat deposition or possibly deposited as air-fall volcanic ash also affected the geochemistry of the coal bed. For example, crandallite(?), a mineral reported to form as an alteration product of volcanic ash, is found in seven samples from the coal bed. The presence of quartz grains containing silicate-melt inclusions in eight samples from the coal bed.provides further support for a volcanic ash component. Other factors that probably affected the geochemistry of the coal bed include (1) detrital input associated with the deposition of the roof rocks of the coal bed, (2) peat-forming processes and plant material, and (3) epigenetic ground-water flow.

Montana, Wyoming↗
USGS1992

Mid-Mesozoic (Mid-Jurassic to Early Cretaceous) evolution of the Georges Bank Basin, U.S. North Atlantic outer continental shelf: Sedimentology of the Conoco 145-1 well

The Conoco 145-1 exploratory well, located in the southeastern portion of the Georges Bank Basin, was drilled to a total depth of 4303 m below the sea floor. The oldest sedimentary rocks sampled are of Middle Jurassic age (Late Bathonian-Callovian). A dolomite-limestone-evaporite sequence dominates the section below 3917 m; limestone is the predominant lithology in the intervals of 3271-3774 m, 2274-3158 m, and 1548-1981 m. Siliciclastics dominate the remainder of the drilled section. Calcite tightly cements most of the rocks below 1548 m; dolomite, silica, siderite, and diagenetic clay cements are locally important. Restricted inner marine environments, representing lagoonal and tidal flat conditions, prevailed at the wellsite during much of the deposition recorded by the Callovian-Bathonian age Iroquois Formation. These environments gave way to a carbonate platform, which formed part of the > 5,000 km long Bahama-Grand Banks gigaplatform that lasted through the end of the Late Jurassic (encompassing the uppermost portion of the Iroquois Formation and the Scatarie Limestone and Bacarro Limestone Members of the Abenaki Formation). The absence of a skeletal-reef association and the dominance of muddy limestone fabrics are evidence that the 145-1 wellsite was located on the platform interior. Major periods of siticiclastic deposition interrupted carbonate deposition, and they are recorded by stratigraphic equivalents of the Mohican Formation, Misaine Shale Member of the Abenaki Formation, and the Mohawk and Mic Mac Formations. A series of sustained prograding delta systems, the earliest of which is preserved as the Missisauga Formation, buried the carbonate platform following its drowning in the Early Cretaceous (Berriasian-Valanginian). The sparser, primarily allochthonous lignite content and better-sorted, glauconite-bearing sands of the Missisauga strata at the 145-1 wellsite suggest that shallow marine or barrier-bar environments were more prevalent than the low delta-plain facies recorded farther shoreward at the COST G-1 wellsite.

Sedimentary Geology↗
USGS1992

Lithology, stratigraphy, and paleoenvironments of the Mobil 312-1 well, Georges Bank Basin, US North Atlantic outer continental shelf

The Mobil 312-1 hydrocarbon exploratory well, southeastern Georges Bank Basin penetrated a section entirely composed of sedimentary rocks that range from Middle to Pliocene age. Carbonates are the dominant lithologies in the intervals at 6096-3444 m, 2560-2096 m and 1067-887 m; siliciclastics make up most of the remaining section. Although inferred paleoenvironments range primarily from supratidal to outer neritic, thin lignitic coal beds at 2204-2195 m and 1929-1920 m record brief periods of nonmarine sedimentation. Middle and Upper Jurassic calcarenites, the drilling targets of the well, have little or no visible porosity and underwent at least three episodes of cementation.

Northeastern Geology↗
USGS1991

Effects of detrital influx in the Pennsylvanian Upper Freeport peat swamp

Quartz cathodoluminescence properties and mineralogy of three sets of samples and vegetal and/ or miospore data from two sets of samples from the Upper Freeport coal bed, west-central Pennsylvania, show that detrital influence from a penecontemporaneous channel is limited to an area less than three km from the channel. The sets of samples examined include localities of the coal bed where (1) the coal is thin, split by partings, and near a penecontemporaneous fluvial channel, (2) the coal is relatively thick and located approximately three km from the channel, and (3) the coal is thick and located approximately 12 km from the channel. Samples from locality 1 (nearest the channel) have relatively high-ash yields (low-temperature ash average = 27.3% on a pyrite- and calcite-free basis) and high proportions of quartz and clay minerals. The quartz is primarily detrital, as determined by cathodoluminescent properties, and the ratio of kaolinite to illite is low. In addition, most of the plant remains and miospores indicate peat-forming plants that required low nutrient levels for growth. In contrast, samples from localities 2 and 3, from the more interior parts of the bed, contained predominantly authigenic quartz grains nd yielded low-temperature ash values of less than 14% on a pyrite- and calcite-free basis. The low-temperature ash contains low concentrations of quartz and clay minerals and the ratio of kaolinite to illite is relatively high. Although intact core was not available for paleobotanical analyses, another core collected within 1 km from locality 3 contained plant types interpreted to have required high nutrient levels for growth. These data indicate that mineral formation is dominated by authigenic processes in interior parts of the coal body. Some of the authigenic quartz may have been derived from herbaceous ferns as indicated by patterns in the palynological and paleobotanical data. In contrast, detrital processes appeared to be limited to in areas directly adjacent to the penecontemporaneous channel where the coal bed is high in ash, split by mineral-rich partings, and of little or no economic value.

International Journal of Coal Geology↗
USGS1991

Facies development in the Lower Freeport coal bed, west-central Pennsylvania, U.S.A.

The Lower Freeport coal bed in west-central Pennsylvania is interpreted to have formed within a lacustrine-mire environment. Conditions of peat formation, caused by the changing chemical and physical environments, produced five coal facies and two mineral-rich parting facies within the coal bed. The coal bed facies are compositionally unique, having developed under varying conditions, and are manifested by megascopic, petrographic, palynologic and quality characteristics. The initial environment of the Lower Freeport peat resulted in a coal facies that is relatively high in ash yield and contains large amounts of lycopod miospores and moderate abundances of cryptotelinite, crypto-gelocollinite, inertinite and tree fern miospores. This initial Lower Freeport peat is interpreted to have been a topogenous body that was low lying, relatively nutrient rich (mesotrophic to eutrophic), and susceptible to ground water and to sediment influx from surface water. The next facies to form was a ubiquitous, clay-rich durain parting which is attributed to a general rise in the water table accompanied by widespread flooding. Following formation of the parting, peat accumulation resumed within an environment that inhibited clastic input. Development of doming in this facies restricted deposition of the upper shale parting to the margins of the mire and allowed low-ash peat to form in the interior of the mire. Because this environment was conducive to preservation of cellular tissue, this coal facies also contains large amounts of crypto-telinite. This facies development is interpreted to have been a transitional phase from topogenous, planar peat formation to slightly domed, oligotrophic (nutrient-poor) peat formation. As domed peat formation continued, fluctuations in the water table enabled oxidation of the peat surface and produced high inertinite concentrations toward the top of the coal bed. Tree ferns became an increasingly important peat contributor in the e upper facies, based on the palynoflora. This floral change is interpreted to have resulted from the peat surface becoming less wet or better drained, a condition that inhibited proliferation of lycopod trees. Accumulation of the peat continued until rising water levels formed a freshwater lake within which clays and silts were deposited. The development of the Lower Freeport peat from a planar mire through transitional phases toward domed peat formation may be an example of the type of peat formation of other upper Middle and Upper Pennsylvanian coal beds.

International Journal of Coal Geology↗
USGS1989

The effects of volcanic ash on the maceral and chemical composition of the C coal bed, Emery Coal Field, Utah

Volcanic ash which fell in the peat swamp that formed the Upper Cretaceous C coal bed (Ferron Sandstone Member of the Mancos Shale, Utah) produced semi-impermeable layers that caused the ponding of surface waters. Coal samples from directly above tonsteins (altered volcanic ash partings) are enriched in desmocollinite, telinite, and detrocollinite, as a result of poorly drained swamp conditions; coal samples from directly below tonsteins are enriched in semifusinite, inertodetrinite, and fusinite, as a result of well-drained conditions. Leaching of the volcanic ash or the incorporation of volcanic ash in peat provided a source for many elements (including Zr, Nb, Th, and Ce) that are enriched in coal samples taken from directly above and below tonsteins.

Utah↗
USGS1989

Comparative facies formation in selected coal beds of the Powder River Basin

Petrologic studies of thick coal beds [Warwick, 1985; Moore, 1986; Moore and others, 1986; Moore and others, 1987; Warwick and Stanton, in press], which build on sedimentological interpretations [Flores, this volume] of associated units, provide data to interpret and contrast the varieties of peat formation in the Powder River Basin. Detailed analyses of the composition of coal beds lead to more complete interpretations regarding the depositional environment on a regional and local scale. Our efforts in the Powder River Basin [areas A-D in fig. 1 of Flores, this volume] have resulted in a series of site-specific studies that interpret the types of peat formation from the arrangement of different facies which comprise the coal beds and from the spatial form of the coal beds. Our approach was to use a combination of megascopic criteria for facies sampling, and where only core was available, to analyze many interval samples to discriminate facies by their maceral composition. Coal beds in the Powder River Basin are composed of laterally continuous, compositional subunits of the bed (facies) that can be discerned most easily in weathered highwall exposures, less readily in fresh highwalls, and very poorly in fresh-cut core surfaces. In general, very low ash (

Montana, Wyoming↗