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Geology topics

Michael E. Brownfield

Publications and source records attributed to Michael E. Brownfield.

At least 163 records · Page 9Linked to original sources
USGS2008

The Yampa Bed — A regionally extensive tonstein in the Williams Fork Formation, northwestern Piceance Creek and southern Sand Wash Basins, Colorado

A regionally persistent and distinctive unit of Upper Cretaceous age is here formally named the Yampa Bed of the Williams Fork Formation for exposures in the Yampa, Danforth Hills, and Grand Hogback coal fields, Moffat and Routt Counties, northwest Colorado; the name is derived from the Yampa River valley. The type section was measured in the NE¼ SW¼ sec. 6, T. 5 N., R. 91 W., about 8 miles south of Craig, Colo., where the bed is 38 inches thick and lies within the C-D coal bed in the lower part of the Williams Fork Formation, about 165 feet above the Trout Creek Sandstone Member of the Iles Formation. The Yampa Bed is dated at 72.2 ± .1 mega-annum using the K-Ar method. Regionally, the Yampa Bed is a 0.5- to 5-ft-thick, regionally persistent tonstein that can be readily identified in several different lithofacies in the lower part of the Williams Fork Formation. The unit is useful as a regional datum in the correlation of facies within the Williams Fork, and it is easily recognized on geophysical logs by its low resistivity response. Evidence suggests that it is a diagenetically altered airfall ash.

Colorado↗
USGS2006

Geology and total petroleum systems of the West-Central Coastal province (7203), West Africa

The West-Central Coastal Province of the Sub-Saharan Africa Region consists of the coastal and offshore areas of Cameroon, Equatorial Guinea, Gabon, Democratic Republic of the Congo, Republic of the Congo, Angola (including the disputed Cabinda Province), and Namibia. The area stretches from the east edge of the Niger Delta south to the Walvis Ridge. The West-Central Coastal Province includes the Douala, Kribi-Campo, Rio Muni, Gabon, Congo, Kwanza, Benguela, and Namibe Basins, which together form the Aptian salt basin of equatorial west Africa. The area has had significant exploration for petroleum; more than 295 oil fields have been discovered since 1954. Since 1995, several giant oil fields have been discovered, especially in the deep-water area of the Congo Basin. Although many total petroleum systems may exist in the West-Central Coastal Province, only four major total petroleum systems have been defined. The area of the province north of the Congo Basin contains two total petroleum systems: the Melania-Gamba Total Petroleum System, consisting of Lower Cretaceous source and reservoir rocks, and the Azile-Senonian Total Petroleum System, consisting of Albian to Turonian source rocks and Cretaceous reservoir rocks. Two assessment units are defined in the West-Central Coastal Province north of the Congo Basin: the Gabon Subsalt and the Gabon Suprasalt Assessment Units. The Congo Basin contains the Congo Delta Composite Total Petroleum System, consisting of Lower Cretaceous to Tertiary source and reservoir rocks. The Central Congo Delta and Carbonate Platform and the Central Congo Turbidites Assessment Units are defined in the Congo Delta Composite Total Petroleum System. The area south of the Congo Basin contains the Cuanza Composite Total Petroleum System, consisting of Lower Cretaceous to Tertiary source and reservoir rocks. The Cuanza-Namibe Assessment Unit is defined in the Cuanza Composite Total Petroleum System. The U.S. Geological Survey (USGS) assessed the potential for undiscovered conventional oil and gas resources in this province as part of its World Petroleum Assessment 2000. The USGS estimated a mean of 29.7 billion barrels of undiscovered conventional oil, 88.0 trillion cubic feet of gas, and 4.2 billion barrels of natural gas liquids. Most of the hydrocarbon potential remains in the offshore waters of the province in the Central Congo Turbidites Assessment Unit. Large areas of the offshore parts of the Kwanza, Douala, Kribi-Campo, and Rio Muni Basins are underexplored, considering their size, and current exploration activity suggests that the basins have hydrocarbon potential. Since about 1995, the offshore part of the Congo Basin has become a major area for new field discoveries and for hydrocarbon exploration, and many deeper water areas in the basin have excellent hydrocarbon potential. Gas resources may be significant and accessible in areas where the zone of oil generation is relatively shallow.

Bulletin↗
USGS2006

Geology and total petroleum systems of the Gulf of Guinea province of West Africa

The U.S. Geological Survey (USGS) assessed the potential for undiscovered conventional oil and gas resources in the Gulf of Guinea Province, west-central Africa, as part of its World Petroleum Assessment 2000. The USGS estimated a mean of 1,004 million barrels of conventional undiscovered oil, 10,071 billion cubic feet of gas, and 282 million barrels of natural gas liquids. Most of the hydrocarbon potential is postulated to be in the offshore, deeper waters of the province.

Bulletin↗
USGS2006

Assessment of Undiscovered Gas Resources of the Eastern Oregon and Washington Province, 2006

Using a geology-based assessment methodology, the U.S. Geological Survey estimated a mean of 2.4 trillion cubic feet (TCF) of undiscovered natural gas in the Eastern Oregon and Washington Province. More than 90 percent, or 2.1 TCF, of the estimated undiscovered natural gas is continuous gas estimated to be trapped in Tertiary rocks overlain by the Columbia River Basalt Group.

Fact Sheet↗
USGS2005

Characterization and modes of occurrence of elements in feed coal and coal combustion products from a power plant utilizing low-sulfur coal from the Powder River Basin, Wyoming

The U.S. Geological Survey and the University of Kentucky Center for Applied Energy Research are collaborating with an Indiana utility company to determine the physical and chemical properties of feed coal and coal combustion products from a coal-fired power plant. The Indiana power plant utilizes a low-sulfur (0.23 to 0.47 weight percent S) and lowash (4.9 to 6.3 weight percent ash) subbituminous coal from the Wyodak-Anderson coal zone in the Tongue River Member of the Paleocene Fort Union Formation, Powder River Basin, Wyoming. Based on scanning electron microscope and X-ray diffraction analyses of feed coal samples, two mineral suites were identified: (1) a primary or detrital suite consisting of quartz (including beta-form grains), biotite, feldspar, and minor zircon; and (2) a secondary authigenic mineral suite containing alumino-phosphates (crandallite and gorceixite), kaolinite, carbonates (calcite and dolomite), quartz, anatase, barite, and pyrite. The primary mineral suite is interpreted, in part, to be of volcanic origin, whereas the authigenic mineral suite is interpreted, in part, to be the result of the alteration of the volcanic minerals. The mineral suites have contributed to the higher amounts of barium, calcium, magnesium, phosphorus, sodium, strontium, and titanium in the Powder River Basin feed coals in comparison to eastern coals. X-ray diffraction analysis indicates that (1) fly ash is mostly aluminate glass, perovskite, lime, gehlenite, quartz, and phosphates with minor amounts of periclase, anhydrite, hematite, and spinel group minerals; and (2) bottom ash is predominantly quartz, plagioclase (albite and anorthite), pyroxene (augite and fassaite), rhodonite, and akermanite, and spinel group minerals. Microprobe and scanning electron microscope analyses of fly ash samples revealed quartz, zircon, and monazite, euhedral laths of corundum with merrillite, hematite, dendritic spinels/ferrites, wollastonite, and periclase. The abundant calcium and magnesium mineral phases in the fly ash are attributed to the presence of carbonate, clay, and phosphate minerals in the feed coal and their alteration to new phases during combustion. The amorphous diffraction-scattering maxima or glass 'hump' appears to reflect differences in chemical composition of fly ash and bottom ash glasses. In Wyodak-Anderson fly and bottom ashes, the center point of scattering maxima is due to calcium and magnesium content, whereas the glass 'hump' of eastern fly ash reflects variation in aluminum content. The calcium- and magnesium-rich and alumino-phosphate mineral phases in the coal combustion products can be attributed to volcanic minerals deposited in peat-forming mires. Dissolution and alteration of these detrital volcanic minerals occurred either in the peat-forming stage or during coalification and diagenesis, resulting in the authigenic mineral suite. The presence of free lime (CaO) in fly ash produced from Wyodak-Anderson coal acts as a self-contained 'scrubber' for SO3, where CaO + SO3 form anhydrite either during combustion or in the upper parts of the boiler. Considering the high lime content in the fly ash and the resulting hydration reactions after its contact with water, there is little evidence that major amounts of leachable metals are mobilized in the disposal or utilization of this fly ash.

Scientific Investigations Report↗
USGS2003

Assessment of the undiscovered oil and gas of the Senegal province, Mauritania, Senegal, the Gambia, and Guinea-Bissau, northwest Africa

Undiscovered, conventional oil and gas resources were assessed in the Senegal Province as part of the U.S. Geological Survey World Petroleum Assessment 2000 (U.S. Geological Survey World Energy Assessment Team, 2000). Although several total petroleum systems may exist in the province, only one composite total petroleum system, the Cretaceous-Tertiary Composite Total Petroleum System, was defined with one assessment unit, the Coastal Plain and Offshore Assessment Unit, having sufficient data to allow quantitative assessment. The primary source rocks for the Cretaceous-Tertiary Composite Total Petroleum System are the Cenomanian-Turonian marine shales. The Turonian shales can be as much as 150 meters thick and contain Type II organic carbon ranging from 3 to 10 weight percent. In the Senegal Province, source rocks are mature even when situated at depths relatively shallow for continental passive margin basins. Reservoir rocks consist of Upper Cretaceous sandstones and lower Tertiary clastic and carbonate rocks. The Lower Cretaceous platform carbonate rocks (sealed by Cenomanian shales) have porosities ranging from 10 to 23 percent. Oligocene carbonate rock reservoirs exist, such as the Dome Flore field, which contains as much as 1 billion barrels of heavy oil (10? API, 1.6 percent sulfur) in place. The traps are a combination of structural closures and stratigraphic pinch-outs. Hydrocarbon production in the Senegal Province to date has been limited to several small oil and gas fields around Cape Verde (also known as the Dakar Peninsula) from Upper Cretaceous sandstone reservoirs bounded by normal faults, of which three fields (two gas and one oil) exceed the minimum size assessed in this study (1 MMBO; 6 BCFG). Discovered known oil resources in the Senegal Province are 10 MMBO, with known gas resources of 49 BCFG (Petroconsultants, 1996). This study estimates that 10 percent of the total number of potential oil and gas fields (both discovered and undiscovered) of at least the minimum size have been discovered. The estimated mean size and number of assessed, undiscovered oil fields are 13 MMBO and 13 fields, respectively, whereas the mean size and number of undiscovered gas fields are estimated to be 50 BCFG and 11 fields. The mean estimates for undiscovered conventional petroleum resources are 157 MMBO, 856 BCFG, and 43 MMBNGL (table 2). The mean sizes of the largest anticipated undiscovered oil and gas fields are 66 MMBO and 208 BCFG, respectively. The Senegal Province is underexplored considering its large size. The province has hydrocarbon potential in both the offshore and onshore, and undiscovered gas resources may be significant and accessible in areas where the zone of oil generation is relatively shallow.

Bulletin↗
USGS2002

Characterization and modes of occurrence of elements in feed coal and fly ash; an integrated approach

Despite certain environmental concerns, coal is likely to remain an important component of the United States energy supply, partly because it is the most abundant domestically available fossil fuel. One of the concerns about coal combustion for electricity production is the potential release of elements from coal and coal combustion products (CCPs) - fly ash - to the environment. This concern prompted the need for accurate, reliable, and comprehensive information on the contents and modes of occurrence of selected elements in power-plant feed coal and fly ash. The U.S. Geological Survey (USGS) is collaborating with several electric utilities to determine the chemical and mineralogical properties of feed coal and fly ash. Our first study analyzed coal and fly ash from a Kentucky power plant, which uses many different bituminous coals from the Appalachian and Illinois Basins. Sulfur content of these feed coals rangedfrom 2.5 to 3.5 percent. The second study analyzed coal and fly ash from an Indiana power plant, which uses subbituminous coal from the Powder River Basin (fig. 1). Sulfur content of this feed coal ranged from 0.23 to 0.47 percent. A summary of important aspects of our approach and results are presented in this report.

Indiana, Kentucky↗
USGS1999

The Niger Delta petroleum system; Niger Delta Province, Nigeria, Cameroon, and equatorial Guinea, Africa

In the Niger Delta province, we have identified one petroleum system--the Tertiary Niger Delta (Akata-Agbada) petroleum system. The delta formed at the site of a rift triple junction related to the opening of the southern Atlantic starting in the Late Jurassic and continuing into the Cretaceous. The delta proper began developing in the Eocene, accumulating sediments that now are over 10 kilometers thick. The primary source rock is the upper Akata Formation, the marine-shale facies of the delta, with possibly contribution from interbedded marine shale of the lowermost Agbada Formation. Oil is produced from sandstone facies within the Agbada Formation, however, turbidite sand in the upper Akata Formation is a potential target in deep water offshore and possibly beneath currently producing intervals onshore. Known oil and gas resources of the Niger Delta rank the province as the twelfth largest in the world. To date, 34.5 billion barrels of recoverable oil and 93.8 trillion cubic feet of recoverable gas have been discovered. In 1997, Nigeria was the fifth largest crude oil supplier to the United States, supplying 689,000 barrels/day of crude.

Open-File Report↗
USGS1998

Maps showing geology, oil and gas fields and geological provinces of Africa

The CD-ROM was compiled according to the methodology developed by the U.S. Geological Survey's World Energy Project . The goal of the project was to assess the undiscovered, technically recoverable oil and gas resources of the world and report these results by the year 2000. A worldwide series of geologic maps, published on CD-ROMs, was released by the U.S. Geological Survey's World Energy Project during 1997-2000. Specific details of the data sources and map compilation are given in the metadata files on this CD-ROM. These maps were compiled using Environmental Systems Research Institute Inc. (ESRI) ARC/INFO software. Political boundaries and cartographic representations on this map are shown (with permission) from ESRI's ArcWorld 1:3M digital coverage: they have no political significance and are displayed as general reference only. Portions of this database covering the coastline and country boundaries contain proprietary property of ESRI. (Copyright 1992 and 1996, Environmental Systems Research Institute Inc. All rights reserved.)

Open-File Report↗
USGS1998

Fischer assays of oil shale drill cores and rotary cuttings from the Piceance Basin, Colorado— 2009 update

This CD-ROM includes updated files containing Fischer assays of samples of core holes and cuttings from exploration drill holes drilled in the Eocene Green River Formation in the Piceance Basin of northwestern Colorado. A database was compiled that includes more than 321,380 Fischer assays from 782 boreholes. Most of the oil yield data were analyzed by the former U.S. Bureau of Mines oil shale laboratory in Laramie, Wyoming, and some analyses were made by private laboratories. Location data for 1,042 core and rotary holes, oil and gas tests, as well as a few surface sections are listed in a spreadsheet and included in the CD-ROM. These assays are part of a larger collection of subsurface information held by the U.S. Geological Survey, including geophysical and lithologic logs, water data, and chemical and X-ray diffraction analyses having to do with the Green River oil shale deposits in Colorado, Wyoming, and Utah. Because of an increased interest in oil shale, this CD-ROM disc containing updated Fischer assay data for the Piceance Basin oil shale deposits in northwestern Colorado is being released to the public.

Colorado↗
USGS1994

McCrillisite, NaCs(Be,Li)Zr2(PO4)4.1-2H2O, a new mineral species from Mount Mica, Oxford County, Maine, and new data for gainesite

McCrillisite, a member of the gainesite group, occurs in the Mount Mica granitic pegmatite, South Paris, Oxford County, Maine. The mineral is a product of late-stage hydrothermal alteration and is associated with approximately 20 other silicate, oxide, carbonate, arsenite and phosphate minerals. Crystals occur in mm- to cm-sized cavities, and individuals are up to 1.2 mm in maximum dimension. The crystallography and mineral chemistry of McCrillisite are described. -from Authors

Canadian Mineralogist↗
USGS1993

Kosnarite, KZr2(PO4)3, a new mineral from Mount Mica and Black Mountain, Oxford County, Maine

Kosnarite, ideally KZr2(PO4)3, has been identified as part of a late-stage, secondary phosphate mineral assemblage from the Mount Mica pegmatite at Paris, and from the Black Mountain pegmatite, Rumford, Oxford County, Maine. Kosnarite from Mount Mica occurs as pseudocubic rhombohedral crystals, as much as 0.9 mm in maximum dimension, that display the dominant {102} form. Color ranges from pale blue to blue-green to nearly colorless. The mineral has a white streak, is transparent, has a vitreous luster, and is nonfluorescent in ultraviolet light. It has a hardness of 4.5, is brittle with a conchoidal fracture, and has perfect {102} cleavage. Kosnarite from Black Mountain is almost pure KZr2(PO4)3 with only trace amounts of Hf, Mn, Na, and Rb. The mineral is one of three known alkali zirconium phosphates; the others are gainesite and the Cs analogue of gainesite. -from Author

American Mineralogist↗