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R.C. Burruss

Publications and source records attributed to R.C. Burruss.

29 records · Page 2Linked to original sources
USGS1997

Measurement of clathrate hydrates via Raman spectroscopy

Raman spectra of clathrate hydrate guest molecules are presented for three known structures ( I ( sI ), II ( sII ), and H ( sH )) in the following systems: CH 4 ( sI ), CO 2 ( sI ), C 3 H 8 ( sII ), CH 4 + CO 2 ( sI ), CD 4 + C 3 H 8 ( sII ), CH 4 + N 2 ( sI ), CH 4 + THF- d 8 ( sII ), and CH 4 + C 7 D 14 ( sH ). Relative occupancy of CH 4 in the large and small cavities of sI were determined by deconvoluting the ν 1 symmetric bands, resulting in hydration numbers of 6.04 ± 0.03. The frequency of the ν 1 bands for CH 4 in structures I, II, and H differ statistically, so that Raman spectroscopy is a potential tool to identify hydrate crystal structure. Hydrate guest compositions were also measured for two vapor compositions of the CH 4 + CO 2 system, and they compared favorably with predictions. The large cavities were measured to be almost fully occupied by CH 4 and CO 2 , whereas only a small fraction of the small cavities are occupied by CH 4 . No CO 2 was found in the small cavities. Hydration numbers from 7.27 to 7.45 were calculated for the mixed hydrate.

Journal of Physical Chemistry B↗
USGS1996

Constraints on the thermal history of Taylorsville Basin, Virginia, U.S.A., from fluid-inclusion and fission-track analyses: Implications for subsurface geomicrobiology experiments

Microbial populations have been found at the depth of 2621-2804 m in a borehole near the center of Triassic Taylorsville Basin, Virginia. To constrain possible scenarios for long-term survival in or introduction of these microbial populations to the deep subsurface, we attempted to refine models of thermal and burial history of the basin by analyzing aqueous and gaseous fluid inclusions in calcite/quartz veins or cements in cuttings from the same borehole. These results are complemented by fission-track data from the adjacent boreholes. Homogenization temperatures of secondary aqueous fluid inclusions range from 120?? to 210??C between 2027- and 3069-m depth, with highest temperatures in the deepest samples. The salinities of these aqueous inclusions range from 0 to ??? 4.3 eq wt% NaCl. Four samples from the depth between 2413 and 2931 m contain both two-phase aqueous and one-phase methane-rich inclusions in healed microcracks. The relative CH4 and CO2 contents of these gaseous inclusions was estimated by microthermometry and laser Raman spectroscopy. If both types of inclusions in sample 2931 m were trapped simultaneously, the density of the methane-rich inclusions calculated from the Peng - Robinson equation of state implies an entrapment pressure of 360 ?? 20 bar at the homogenization temperature (162.5 ?? 12.5??C) of the aqueous inclusions. This pressure falls between the hydrostatic and lithostatic pressures at the present depth 2931 m of burial. If we assume that the pressure regime was hydrostatic at the time of trapping, then the inclusions were trapped at 3.6 km in a thermal gradient of ??? 40??C/km. The high temperatures recorded by the secondary aqueous inclusions are consistent with the pervasive resetting of zircon and apatite fission-track dates. In order to fit the fission-track length distributions of the apatite data, however, a cooling rate of 1-2??C/Ma following the thermal maximum is required. To match the integrated dates, the thermal maximum would have occurred at ??? 200 Ma. The timing of the maximum temperature is consistent with rapid burial of the Taylorsville Basin to twice its present-day depth and thermal re-equilibration with a 40??C/km geothermal gradient, followed by slow exhumation. The results may imply that the microorganisms did not survive in situ, but were transported from the cooler portions of the basin sometime after maximum burial and heating.

Chemical Geology↗
USGS1996

A composite phase diagram of structure H hydrates using Schreinemakers' geometric approach

A composite phase diagram is presented for Structure H (sH) clathrate hydrates, In this work, we derived the reactions occurring among the various phases along each four-phase (Ice/Liquid water, liquid hydrocarbon, vapor, and hydrate) equilibrium line. A powerful method (though seldom used in chemical engineering) for multicomponent equilibria developed by Schreinemakers is applied to determine the relative location of all quadruple (four-phase) lines emanating from three quintuple (five-phase) points. Experimental evidence validating the approximate phase diagram is also provided. The use of Schreinemakers' rules for the development of the phase diagram is novel for hydrates, but these rules may be extended to resolve the phase space of other more complex systems commonly encountered in chemical engineering.

Fluid Phase Equilibria↗
USGS1992

Laser-excited fluorescence of rare earth elements in fluorite: Initial observations with a laser Raman microprobe

Fluorescence emission spectra of three samples of fluorite containing 226–867 ppm total rare earth elements (REE) were excited by visible and ultraviolet wavelength lines of an argon ion laser and recorded with a Raman microprobe spectrometer system. Narrow emission lines (< 1 nm) due to 4f-4f electron transitions in individual trivalent REE (Pr, Nd, Sm, Eu?, Tb, Dy, Ho, Er, Tm) were observed in the wavelength range of 400–900 nm. Emission from individual REE occur in bands of overlapping lines in the wavelength intervals of 470–495 nm, 535–560 nm, 565–580 nm, 585–620 nm, 640–643 nm, 671.4 nm, and 758.2 nm. A broad band at 419 nm excited by the 363.8-nm ultraviolet line of the laser is due to a 4f-5 d transition in Eu 2+ . Two bands of enigmatic origin are a narrow line at 682.8 nm present at all excitation wavelengths in only one sample and a broad band at 720 nm. We have tentatively assigned individual REE to specific lines in each emission band based on selection rules for strongly and weakly allowed 4f-4f transitions and the position of absorption and emission bands documented in the literature for REE in CaF 2 and LaF 3 host crystals. Working curves of integrated peak intensity of emission from Er 3+ and Eu 2+ vs. ppm measured by ICP-MS give linear log-log fits with R 2 > 0.9 for Eu 2+ and 0.99 for Er 3+ . Detection limits for three micrometer spots are about 0.01 ppm Eu 2+ and 0.07 ppm Er 3+ . These limits are less than chondrite abundance for Eu and Er, demonstrating the potential microprobe analytical applications of laser-excited fluorescence of REE in fluorite. However, application of this technique to common rock-forming minerals may be hampered by competition between fluorescence emission and radiationless energy transfer processes involving lattice phonons.

Geochimica et Cosmochimica Acta↗
USGS1991

Petrogenesis and geological history of a uranium source rock: a case study in northeastern Washington, U.S.A.

A small (4 km 2 ) drainage basin in northeastern Washington contains highly uraniferous groundwater and highly uraniferous peaty sediments of Holocene age. The U is derived from granitic bedrock that underlies the entire drainage basin and that contains 9–16 ppm U. This local bedrock was studied by petrographic, chemical and isotopic methods to determine conditions of its petrogenesis and post-emplacement history that may have contributed to its present high U content and source-rock capability. The original magma was derived by anatexis of Precambrian continental crust of probable mixed metaigneous and metasedimentary character. Mineral-melt partitioning controlled the enrichment of U in chemically evolved phases of the crystallizing melt. Following emplacement in the upper crust at ∼100Ma, the pluton interacted with meteoric-hydrothermal water at ambient temperatures 300°C. Locally intense fracturing promoted alteration, and fracturing and alteration probably continued during later regional uplift in the Eocene. Regional uplift was followed by low-temperature alteration and weathering in the middle to late Tertiary. The combined result of hydrothermal alteration and low-temperature alteration and weathering was the redistribution of U from primary mineral hosts such as allanite to new sites on fracture surfaces and in secondary minerals such as hematite. Zones of highly fractured and altered rock show the most obvious evidence of this process. A model is proposed in which high-angle fractures beneath the drainage basin were the sites of Tertiary supergene enrichments of U. Recent glacio-isostatic uplift has elevated these older enriched zones to shallow levels where they are now being leached by oxidizing groundwater. The chemistry, mineralogy, texture and geological history of this U source-rock suggest criteria for locating other granitic terrane that may contain uraniferous waters and associated young surficial U deposits. The details of U distribution and mobility at this site also apply to the general topic of U mobility in granitic rocks.

Washington↗
USGS1990

Activators of photoluminescence in calcite: evidence from high-resolution, laser-excited luminescence spectroscopy

Laser-excited luminescence spectroscopy of a red-algal, biogenic calcite and a synthetic Mn-calcite can make the distinction between organic and trace-element activators of photoluminescence. Organic-activated photoluminescence in biogenic calcite is characterized by significant peak shifts and increasing intensity with shorter-wavelength excitation and by significant decreases in intensity after heating to ??? 400??C. In contrast, Mn-activated photoluminescence shows no peak shift, greatest intensity under green excitation and limited changes after heating. Examination of samples with a high-sensitivity spectrometer using several wavelengths of exciting light is necessary for identification of photoluminescence activators. ?? 1990.

Chemical Geology↗
USGS1990

Hydrocarbon-water interactions during brine migration: Evidence from hydrocarbon inclusions in calcite cements from Danish North Sea oil fields

Crude oils in primary and secondary fluid inclusions in calcite from fractures in seven offshore oil fields associated with diapiric salt structures in the Danish sector of the North Sea were analyzed by capillary column gas chromatography and compared with crude oils produced from the same reservoirs. Oils from fluid inclusions in all fields show evidence of biodegradation (decreased n - C 17 /pristane and n - C 18 /phytane ratios and loss of n-C 7 , 2-methyl hexane, and 3-methyl hexane relative to methyl cyclohexane) and water washing (absence of benzene and depletion of toluene). Some oils in inclusions are extremely enriched in C 6 and C 7 cyclic alkanes suggesting that these samples contain hydrocarbons exsolved from ascending, hotter formation waters. Compared to inclusion oils the produced oils are less biodegraded, but are water washed, indicating that both types of oil interacted with large volumes of formation water. The carbon isotopic composition of the calcite host of the fluid inclusions in the Dagmar and Skjold fields is as light as −16.5%. PDB and the sulfur isotopic composition of pyrite in and adjacent to the calcite veins in the Skjold field is as light as −39.6%. CDT, indicating that biodegradation of the oils was a source of some of the carbon in the calcite and sulfate reduction was the source of sulfur for the pyrite. The evidence for microbial degradation of petroleum is consistent with present-day reservoir temperatures (65°–96°C) but is not consistent with previous estimates of the temperatures of calcite vein filling (95°–130°C) which are much higher than the temperatures of known occurrences of biodegraded oil.

Geochimica et Cosmochimica Acta↗
USGS1989

Geochemistry of oils and hydrocarbon source rocks, greater Anadarko Basin: evidence for multiple sources of oils and long-distance oil migration

Organic geochemical analyses of 104 crude oils and 190 core samples of dark-colored shales from the greater Anadarko basin show three major oil types which generally correlate with reservoir age and source-rock age. Analyses include C 3 -C 30 whole-oil gas chromatography, C 10+ saturated-hydrocarbon-fraction gas chromatography, and carbon stable isotopes (ppt relative to PDB) of saturated (sat) and aromatic (arom) hydrocarbon fractions. Three samples from Middle Ordovician Simpson Group reservoirs are "typical" Ordovician oils (type 1), having strong odd-carbon predominance in the C 13 to C 19 n-alkanes, containing little or no acyclic isoprenoids, an &delta; 13 C values of -33.9 ppt (sat) and -33.7 ppt (arom). Oils from Silurian to Devonian and Mississippian reservoirs (type 2) show little or no odd-carbon predominance in the n-alkanes, a regular decrease in abundance of n-alkanes with increasing carbon number, pristane/phytane ratios (pr/ph) of 1.1 to 1.5, and &delta; 13 C values of -30.6 ppt (sat) and -30.1 ppt (arom). Oils in Pennsylvanian reservoirs (type 3) have the greatest amounts of C 15+ hydrocarbons, are isotopically heavy (-27.5 ppt [sat] and -26.4 ppt [arom]), have methyl-cyclohexane as the most abundant hydrocarbon, and have pr/ph values from 2.0 to 0.9. Oils from the Kansas shelf area of the Anadarko basin are similar to the Anadarko oil types except that they have only traces of toluene and no detectable benzene. The relative abundance of toluene in the C 7 hydrocarbons systematically decreases with distance from the depocenter of the basin. The aromatic compounds are removed by water-washing, and hence could have been lost by contact with progressively greater amounts of formation water during long-distance migration. The lack of thermally mature source rocks in southern and central Kansas supports this hypothesis.

Oklahoma↗