East-central Texas Research Articles

Petrography and geochemistry of selected lignite beds in the Gibbons Creek mine (Manning Formation, Jackson Group, Paleocene) of east-central Texas

This study examined the petrographic and geochemical characteristics of two lignite beds (3500 and 4500 beds, Manning Formation, Jackson Group, Eocene) that are mined at the Gibbons Creek mine in east-central Texas. The purpose of the study was to identify the relations among sample ash yield, coal petrography, and trace-element concentrations in lignite and adjoining rock layers of the Gibbons Creek mine. Particular interest was given to the distribution of 12 environmentally sensitive trace elements (As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, and U) that have been identified as potentially hazardous air pollutants (HAPs) in the United States Clean Air Act Amendments of 1990. Eleven lignite, floor, and rock parting samples were collected from incremental channel samples of the 3500 and 4500 beds that were exposed in a highwall of pit A3 at the Gibbons Creek mine. Short proximate and ultimate and forms of sulfur analyses were performed on all lignite samples, and lignite and rock samples were analyzed for 60 major, minor and trace elements. Representative splits of all lignite samples were ground and cast into pellets, and polished for petrographic analyses in blue-light fluorescence and reflected white light to determine liptinite, inertinite, and huminite maceral group percentages. The following observations summarize our results and conclusions about the geochemistry, petrography, and sedimentology of the 3500 and 4500 beds of the Gibbons Creek lignite deposit: (1) Weighted average dry (db) ash yield for the two beds is 29.7%, average total sulfur content is 2.6%, and average calorific value is 7832 Btu (18.22 MJ/kg). Ash yields are greatest in the lower bench (59.33% db) of the 3500 bed and in the upper bench of the 4500 bed (74.61% db). (2) For lignite samples (on a whole-coal basis), the distributions of two of the HAPs (Pb and Sb) are positively related to ash yield, probably indicating an inorganic affinity for these elements. By using cluster analysis we found that Be and Cd were poorly associated with ash yield, indicating a possible organic affinity, and that Ni, Se, Hg, U, and Pb cluster with most of the rare-earth elements. (3) The dominance of the crypto-eugelinite maceral subgroup over the crypto-humotelinite subgroup suggests that all Gibbons Creek lignites were subjected to peat-forming conditions (either biogenic or chemical) conducive to the degradation of wood cellular material into matrix gels, or that original plant material was not very woody and was prone to formation of matrix gels. The latter idea is supported by pollen studies of Gibbons Creek lignite beds; results indicate that the peat was derived in part from marsh plants low in wood tissue. (4) The occurrence of siliceous sponge spicules in the lower benches of the 3500 bed suggests the original peat in this part of the bed was deposited in standing, fresh water. (5) The petrographic data indicate that the upper sample interval of the 3500 bed contains more inertinite (3%) than the other samples studied. Increases in inertinite content in the upper part of the 3500 bed may have been associated with alteration of the peat by acids derived from the volcanic ash or could have been caused by fire, oxidation and drying, or biologic alteration of the peat in the paleo-mire.

Palynology and paleoecology of lignites from the Manning Formation (Jackson Group) outcrop in the Lake Somerville spillway of east-central Texas

Four palynomorph assemblages, whose parent plants contributed to the formation of the lignite, occur in the lignite seams and associated sediments from the Manning Formation (Jackson Group) outcrop in the Lake Somerville spillway of Texas. The Cicatricosisporites-Laevigatosporites fern assemblage occurs in the middle and upper seam and probably derived from a freshwater herbaceous mire community. The Momipites coryloides-Arecipites columellus-Liliacidites assemblage occurs in all three seams and probably derived from a freshwater mire forest with an open canopy or shrub community. The Momipites coryloides-Nyssa-Rhoipites angustus assemblage occurs in the lower and middle seams and probably derived from a different freshwater mire forest. The Cupuliferoipollenites-Cupuliferoidaepollenites liblarensis-Siltaria cf. S. scabriextima assemblage occurs at the top of the lower and middle seams, which are overlain by marine sediments. The association between Cupuliferoipollenites dominance and the presence of marine diatoms and brackish or marine trace fossils in the lignite suggests that this assemblage may have derived from a mangrove (i.e. marine or brackish) mire forest. However, other factors may influence its distribution. Ailanthipites berryi, possibly derived from a tree or shrub related to the ‘tree of heaven’, predominates in the claystone underlying the lower lignite seam and may have colonized the coastal plain prior to the initiation of peat accumulation. We can differentiate lignite samples dominated by fern spores, Momipites pollen and Cupuliferoipollenites pollen based on gas chromatography-mass spectrometry (GC-MS) fragmentograms of triterpanes (m/z 191) and steranes (m/z 217). The lignite layers dominated by each palynomorph assemblage appear to have distinct sources and different early diagenetic (pre-coalification) histories.

What's up, Billy Jo? Deaf children and bilingual-bicultural instruction in east-central Texas.

Seven deaf children attended a bilingual-bicultural (bi-bi) prekindergarten, kindergarten, and first grade from 1993 to 1996 in an east-central Texas public school. The children had diverse backgrounds (African American, Hispanic, White) and various intellectual, cognitive, and linguistic abilities. We detail the backgrounds of the seven children and their families and describe three bi-bi classrooms. We present standardized test scores on cognition (Bracken Test of Basic Concepts) and academic achievement (Stanford Achievement Test, 9th edition, and Woodcock-Johnson Psycho-Educational Battery). When, with one exception, the children completed first grade, they all tested at grade level. (The exception was a younger child who had only completed kindergarten but who nonetheless tested at the first-grade level). We interpret our findings in light of theories of first- and second-language acquisition and discuss the feasibility of establishing bi-bi programs in areas where no large Deaf community exists. We also note our plans to evaluate the seven children again, at the end of second grade in spring 1997.

Geochemistry of Water and Mobilization and Transport of Solutes in Coal Mine Spoils, East-Central Texas

Reclamation of surface mines in Texas became mandatory in 1978, requiring that overburden removed during surface mining (mine spoils) be emplaced in open mine pits and land surface reshaped to pre-mining topography. The reclaimed land surface then is revegetated to control erosion. Shallow ground-water-flow systems that develop in reclaimed areas have geochemical characteristics substantially different from pre-mining conditions. Because the solutes produced by mine spoils potentially can degrade the quality of ground and surface water, the mining industry has developed methods of spoils emplacement and surface reclamation to mitigate these effects. Comparisons of chemical data from ground water collected from two coal mine reclamation sites in east-central Texas and results of a laboratory-controlled, column-leaching experiment on reclaimed spoil material from the area indicate that large amounts of solutes are mobilized from the spoil material. Increased concentrations of dissolved solids (550 to 6,050 milligrams per liter), dissolved sulfate (73 to 2,800 milligrams per liter), dissolved iron (2,000 to 160,000 micrograms per liter), and dissolved manganese (800 to 13,000 micrograms per liter) and low pH (4.0 to 6.2) in ground water from two reclaimed areas indicate these to be the primary water-quality concerns. However, reclamation practices and establishment of strongly reducing environmentsmore » in shallow ground water inhibit mobilization and transport of trace elements (including radium-226 and uranium-238, which are present in very small amounts in the ground water). Mass-balance models indicate that pyrite oxidation and dissolution of halite, carbonates, amorphous alumina, amorphous silica, and to a lesser extent, gypsum are reaction processes occurring in reclaimed spoils. Sulfate reduction was apparent in the aquifers from detection of sulfide in ground water; however, the magnitude of sulfate reduction was not substantial in mass-balance models.« less

Composition and Provenance of Volcanic Glass in Late Eocene Manning Formation, East-Central Texas: ABSTRACT

ABSTRACT Airfall volcanic ash beds in the Late Eocene Manning Formation, Brazos River Valley, Texas, contain large quantities of hydrated, but otherwise unaltered and non-corroded, rhyolitic glass shards, along with mica, sanidine, and quartz crystals. Enclosing deposits contain well preserved siliceous microfossils (diatoms, sponge spicules, phytoliths). Unaltered glass occurs only where volcanic ash was deposited in nonmarine, non-swamp environments: lacustrine, fluvial, and forested soil surface. Composition of glass shards from the upper part and top of the Manning Formation was determined by broad-beam electron microprobe analysis. Glasses from four ash beds analyzed to date are very similar in major and minor element composition. The mean and standard deviation in weight% oxides for 398 shards are: 72.7% SiO2 (Standard deviation 0.7%), 11.6% Al2O3 (0.2),5.7% K20 (0.5),2.4% Na2O (0.3),0.7% FeO (0.2), 0.4% CaO (0.1), and 6.5% H2O (by difference). Na and possibly K have likely been substantially leached from glass shards during hydration. MgO, MnO, TiO2, P2O5, and SO3 are all less than 0.2% (below detection limit). The youngest ash layer (top Manning) contains 0.9% FeO compared to 0.7% FeO for two ash layers in the middle Manning and 0.5% FeO for the oldest ash layer in the lower Manning. A possible source for these glasses would be the Sierra Madre Occidental in west Mexico. Age (34.9 and 34.4 Ma for two of the ash beds) and composition is dissimilar to most rhyolites in the Davis Mountains of west Texas.

Kriging of Eocene Sand Channels From Depth-Averaged I Overburden pH, Jewett Lignite Surface Mine, East-Central Texas

Ordinary point kriging was used to map twenty-six vertically-averaged soil and oxidized overburden acidity values for a future mine block at the Jewett lignite mine, east-central Texas. The pH data were collected as part of a geochemical overburden characterization study to be used in post-mining reclamation decision-making. The authors used kriging, and its estimation standard error, to test the completeness of their data set and to indicate areas of need for additional closely spaced sampling. Because pH can be readily measured in the field, they chose it as the parameter of interest in the kriging. In general pH increased with depth; however, a more exciting result was that the trend and geometry of a major paleo-channel could be mapped from pH values because of the relatively higher acidity of the sand in the channel. Kriged maps were compared with manually-contoured and inverse-distance weighting interpolated maps, and found to be more easily interpretable. The kriging performed better because it allows of anisotropies in the data to be naturally included in the interpolation. Prior to the kriging, the data were studied to validate the assumptions involved in the modeling. The data are clean, well-behaved and statistically homogeneous, and the interpolation was successfulmore » even with sparse data. The knowledge of the location and morphology of the paleochannels is essential for the engineering aspects of the mining, and is useful in reclamation decision-making.« less

Late Quaternary Floodplain History of the Brazos River in East-Central Texas

The floodplain along a 75-km segment of the Brazos River, traversing the Gulf Coastal Plain of Texas, has a complex late Quaternary history. From 18,000 to 8500 yr B.P., the Brazos River was a competent meandering stream that migrated from one side of the floodplain to the other, creating a thick layer of coarse-grained lateral accretion deposits. After 8500 yr B.P., the hydrologic regime of the Brazos River changed. The river became an underfit meandering stream that repeatedly became confined within narrow and unstable meander belts that would occasionally avulse. Avulsion occurred four times; first at 8100 yr B.P., then at 2500 yr B.P., again around 500 yr B.P., and finally around 300 yr B.P. The depositional regime on the floodplain also changed after 8500 yr B.P., with floodplain construction dominated by vertical accretion. Most vertical accretion occurred from 8100 to 4200 yr B.P. and from 2500 to 1250 yr B.P. Two major and three minor periods of soil formation are documented in the floodplain sequence. The two most developed soils formed from 4200 to 2500 yr B.P. and from around 1250 to 500 yr B.P. These changes on the floodplain appear to be the result not of a single factor, but of the complex interplay among changes in climate, sediment yield, and intrinsic floodplain variables over time.

Opinions of rural Texas parents concerning elementary school health education.

Parents of elementary school children in rural east-central Texas were surveyed about their attitudes toward and knowledge of Comprehensive School Health Education. Data indicated widespread support for health education compared to other subject areas. Parents felt alcohol and other drugs, nutrition, and first aid were the most important topics to be covered in elementary school, while sexuality, cancer, and stress were the least important. Parents were most comfortable discussing alcohol and other drugs, family life, and growth and development with their children and least comfortable discussing exercise, cancer, and sexuality. Implications for school health programs are discussed.

645 PB 407 FIELD STUDY OF BLACK SPOT RESISTANCE IN ROSE

Forty-five rose genotypes including modem cultivars and rose species were evaluated in a field trial for resistance to black spot caused by Marssonina rosae. The trial was designed as a randomized block with four replications at two sites. The plots were planted at College Station (East Central Texas) and Overton (Northeast Texas). Ratings were done for the percentage of leatlets with black spot lesions and for leaf defoliation. These ratings were taken four times during the growing season from May to October 1993. Preliminary results indicate a high degree of resistance in the ten species studied, Modem cultivars were equally divided into moderate resistance, low resistance, and susceptible with only four showing high resistance. Disease pressure was higher and occurred earlier in the season at the Overton site. Disease pressure was highest at both sites in late spring and again in fall. Pressure was lowest in August after a prolonged period without rain. Introduction during the growing season of a previously unseen race of the pathogen was observed by the performance of the cultivar Sunbright.

Tonsteins and Clay-Rich Layers in Coal-Bearing Intervals of the Eocene Gibbons Creek Member, Manning Formation, East-Central Texas: ABSTRACT

Samples from five clay-rich layers collected from the coal-bearing interval in the upper part of the Eocene Gibbons Creek member of the Manning Formation were mounted in epoxy, polished, and analyzed by scanning electron microscopy and energy-dispersive x-ray fluorescence to determine their origin. Two layers were from surface-mine exposures of the 3500 bed near Bryan, Texas, and the other layers were from an exposure of a correlative interval at the Lake Somerville Spillway about 60 km southwest of Bryan. Preliminary data suggest that both a 2-cm-thick claystone from the upper part of the 3500 bed and the upper part of an 11-cm-thick mudstone from the floor of the lower coal bed at the spillway may be derived from volcanic ash falls. Both possible tonsteins are composed of kaolinite and accessory quartz, euhedral to subhedral zircon, feldspars, and Al phosphates (crandallite?). Only K-feldspars were observed in the parting from the 3500 bed, whereas both alkali and plagioclase feldspars, as well as high-Ti biotites, were observed in the sample from the spillway. These compositional differences are suggestive of two separate volcanic sources. Because waterborne, recycled volcanic minerals could have been brought into the paleopeat swamps, we must examine the associated minerals frommore » these sites to verify ash-fall origins. The other layers contain textures that are more suggestive of detrital rather than ash-fall origin; rounded to subrounded zircons and feldspars are present as accessory minerals.« less

Sequence-Stratigraphic Elements and Geochemical Variability Within a Condensed Section": Eagle Ford Group, East-Central Texas: ABSTRACT"

Sequence-Stratigraphic Elements and Geochemical Variability Within a Condensed Section": Eagle Ford Group, East-Central Texas: ABSTRACT"

Triassic Stratigraphy and Correlation, East-Central New Mexico and West Texas: ABSTRACT

Triassic Stratigraphy and Correlation, East-Central New Mexico and West Texas: ABSTRACT

Races ofPuccinia graminisin the United States During 1990

Wheat stem rust overwintered in southern and east central Texas, southern Louisiana, and southeastern Alabama. Yield losses to stem rust of wheat were traces, but a 1% yield loss in barley occurred in North Dakota. Race Pgt-QCCJ was the most common race, making up 50% of the 450 isolates from 170 collections. If only the 89 collections from wheat were considered, the most common races were Pgt-TPMK, QFCS, and QCCJ, comprising 53, 21, and 16% of the isolates, respectively. Eighty percent of the isolates of QCCJ were from cultivated barley, and 90% of all isolates from cultivated barley were race QCCJ. No virulence was found to wheat lines with «single» genes Sr13, 22, 24, 25, 26, 27, 29, 30, 31, 32, 33, 37, Gt, or Wld-1

Relating Sequence Stratigraphy to Lithostratigraphy in Paleogene Siliciclastic-Dominated Shelf Settings, Central-East Texas

The western Gulf of Mexico is a passive margin with high rates of sedimentation where lithostratigraphy is controlled by sedimentation pulses related to distant tectonism. These pulses exert much control on long-term transgressions and regressions. Superimposed on these long-term cycles are higher orders of cyclicity related to eustatic sea level change (sequences, parasequences), producing a complex history of shoreline change in which sequence stratigraphy is superimposed upon, but unrelated to, lithostratigraphy. lithostratigraphic and sequences stratigraphic relationships of Paleogene deposits in the Brazos River Valley section were studied using seismic, well, logs, outcrop, and core. Paleocene Midway deposits contain midshelf highstand shales with minor lowstand and transgressive sands, whereas Wilcox and Eocene deposits contain shoaling-upward highstand deposits with minor deepening-upward transgressive deposits. Formations commonly contain multiple sequences. The Yegua and Jackson intervals are characterized by patchy development (in time and space) of sand units from outcrop to mid-outer shelf settings. Formation-scale depositional trends are generalized and fragmented due to abrupt shifts in depositional environments at sequence/parasequence boundaries. Fragmentation of depositional gradient within formations occurs laterally and vertically. Thus, regional correlations of lithostratigraphic units represent matching of unconnected depositional episodes. Unlike formations, sequences and parasequences display orderly and predictable progression of depositionalmore » change. Shoaling-upward sand units and flooding surfaces within parasequences are relatively continuous. Parasequences of the Claiborne can be correlated between outcrop and subsurface from shore zone to the mid-outer shelf, crossing formation-scale facies boundaries.« less

Three Basin Model for Central East Texas: Basement Structure and Sedimentary Fill

Three Basin Model for Central East Texas: Basement Structure and Sedimentary Fill

Paluxy of the Central Basin: East Texas

The Paluxy Formation (Lower Cretaceous) has been a consistent sandstone exploration objective in the central East Texas basin, occurring at moderate depths on the order of 5000-8000 ft with oil in reservoirs with good permeability and porosity and reserves in the range of 200,000 to 500,000 bbl per well. Since the 1940s, the pace of Paluxy field discovery has been steady, generally a new field or two every one or two years, and there is every reason to believe that there is continued potential for the Paluxy in the future. The central part of the East Texas basin, in Smith County and adjacent areas, has complex structure with numerous salt domes and intervening sediment wedges (turtles) that formed during movement of the salt. Paluxy oil and gas in this area occurs mainly in combination structural-stratigraphic traps along normal faults that cut turtles. Major exploration trends in the central basin include (1) the Lindale turtle with a number of widely spaced fields, generally with only a few wells but with relatively good per-well reserves, (2) the Tyler turtle with the largest fields and some of the most prolific Paluxy production in the central basin, (3) the Flint and Irene turtles withmore » relatively thin sandstones and modest production, (4) the Lane Chapel turtle with some exciting new Paluxy discoveries, and (5) the rim areas of salt domes.« less

Sediment and Nutrient Loss from Clay Soils as Affected by Tillage

AbstractAgricultural source pollution of water resources has been a source of concern in recent years. Research is needed to define mechanisms of chemical and sediment loss in runoff from agricultural land, and to develop management practices that minimize transport of these pollutants. This study was designed to compare the effect of no‐till (NT) and conventional chisel‐till (CT) soil management on runoff water volumes, sediment loss, and N and P loss from small watersheds on a clay soil. Three NT and three CT watersheds located on Houston Black clay vertisol soil (fine, montmorillonitic, thermic, Udic Pellusterts) in east central Texas were used for the study. Wheat (Triticum aestivum L.), corn (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench] were grown rotationally on the watersheds from 1984 to 1989. Runoff amounts, sediment loss, and N and P losses were measured for each rainfall event that produced runoff. Runoff volume was not changed by tillage system and sediment loss and N and P losses in runoff were less, on average, from NT than from CT. Runoff averaged 1.3 ML ha−1 annually for both CT and NT. Average annual quantities for sediment and nutrient losses were: 160 kg ha−1 and 1575 kg ha−1 for sediment, 3.8 kg ha−1 and 8.1 kg ha−1 for N, and 0.8 kg ha−1 and 1.5 kg ha−1 for P for NT and CT, respectively. These results indicate that the loss of sediment and nutrients from agricultural lands could be minimized by using NT on clay soils.

Petroleum geochemistry of Texas and Oklahoma oils along the Marathon—Ouachita fold-thrust belt, south-central U.S.A.

The Marathon uplifit of west Texas and the Ouachita Mountains of Oklahoma and Arkansas comprise the surface expressions of a Paleozoic orogenic belt extending across the south-central U.S.A. A century of petroleum exploration in the Marathons and Ouachitas has yielded several oil discoveries. In this study, detailed molecular, elemental and isotopic data are presented for 9 Texas oils, 5 Oklahoma oils and 4 Oklahoma solid bitumens, all associated with thrust belt rocks of west Texas and southeast Oklahoma. Oil-oil correlations are proposed, and the character of the organic matter in the source rock(s) is inferred from knowledge of the oil chemistry. At least 16 of the 18 Marathon-Ouachita fold-thrust belt oils/solid bitumens originate from the same (or very similar) organic facies, despite a geographic separation along the fold-thrust belt of > 700 mi (∼ 1125 km). Many of the chemical differences in these samples derive from secondary effects, including biodegradation (e.g., solid bitumens) and differing levels of thermal maturity. The occurrence of unusual chemical compounds (e.g., 25,28,30-trisnorhopane) in some samples indicates the presence of anaerobic bacteria in isolated locales during deposition. Isotopic variability, when interpreted in light of near-constant molecular composition in the oils and an extensive period of early Paleozoic “starved trough” source-rock deposition, implies that these oils originate from rocks of similar organic facies, with source-rock ages ranging from Devonian through Ordovician. Previous literature suggests either a Devonian or an Ordovician source for these oils; molecular and isotopic data of the present study do not allow a distinction to be made. These results, when interpreted in terms of depositional patterns during early Paleozoic time, suggest that oil source rocks and the Marathon-Ouachita fold-thrust belt oil type may be present in the subsurface of central and east-central Texas.

Contrasts in Incised Valley Geometry and Facies Architecture of Quaternary High and Low Sediment Yield Fluvial Systems of the East-Central Texas Continental Shelf

Contrasts in Incised Valley Geometry and Facies Architecture of Quaternary High and Low Sediment Yield Fluvial Systems of the East-Central Texas Continental Shelf

Stratigraphic placement of the Santonian-Campanian boundary (Upper Cretaceous) in the North American Gulf Coastal Plain and Western Interior, with implications to global geochronology

Recent micro- and macropaleontological research in the northern Aquitaine Basin of France, the stratotypic area for the Upper Cretaceous Santonian and Campanian Stages, was used to resolve a long-standing discrepancy in the stratigraphic position of the Santonian-Campanian boundary in east-central Texas as based upon zonations of planktonic foraminifers versus ammonites. On the basis of the presence in Texas of species of ammonites restricted to the lower reaches of the basal Campanian Placenticeras bidorsatum Zone of the Aquitaine Basin, the Santonian-Campanian boundary in Texas is significantly lower than has generally been considered by micropaleontologists. Specifically, it is within the foraminifer-based Globotruncana (= Marginotruncana ) concavata Zone ( sensu lato ). Such placement involves middle reaches of the type Austin Chalk, perhaps within the Dessau Chalk Member. An assumption that underlies the following conclusions is that the boundaries of the G. concavata Zone as recognized in European Tethys, the Atlantic and Caribbean basins, and North American Gulf Coast represent approximately synchronous stratigraphic levels. The following represent additional conclusions of pertinence to global chronology of the Cretaceous. (1) Rather than being younger than the Globotruncana concavata Zone, the Placenticeras bidorsatum Zone should be thought of as being contemporary with at least the younger half of the G. concavata (species total range) Zone. (2) Most of the Merchantville and Magothy Formations on the Atlantic seaboard of New Jersey and Delaware were deposited during early Campanian time, rather than principally during the Santonian. (3) The traditional placement of the Santonian-Campanian boundary in the Western Interior of North America slightly below the zone of Scaphites hippocrepis I is essentially correct. (4) The chronology of the Niobrara Formation of the North American Western Interior as based upon planktonic foraminifers is shown to be in serious error; specifically, it has been considered much too young. (5) Paleomagnetically sampled parts of the Niobrara Formation probably correlate with upper reaches of the “Cretaceous Long Normal Interval”, below magnetochron 33R. (6) Although the Santonian Stage surely represents a surprisingly brief interval of earth history, the Coniacian-Santonian boundary probably should be placed below the G. concavata Zone. (7) The Santonian-Campanian boundary slightly post-dates initiation of the last general Cretaceous regression of the North American Western Interior Seaway. (8) The beginning of the North American Aquilan Land Mammal “Age” represents earliest Campanian time. (9) Rather than representing an earliest Campanian geomagnetic event, the temporal span of global magnetochron 33R equates with approximately the second quarter of the total duration of the Campanian.