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C.E. Barker

Publications and source records attributed to C.E. Barker.

At least 19 recordsLinked to original sources
USGS2007

A problem with estimating the pseudo- activation energy of kerogen thermal maturation from Connan's time-temperature relation in oil genesis.

Connan's time-temperature relation in oil genesis as derived from first-order reaction kinetics is algebraically correct, but its application to natural petroleum generation is invalidated by the assumption that the ratio of initial kerogen concentration to degraded kerogen concentration is constant from deposition to the initiation of intense oil generation. The ratio can only remain constant if no reaction is occurring and, therefore, Connan's data on 'reaction time' in petroleum generation (assumed to be the age of the sediment) only measures the time elapsed since the system formed. Thus, the widely cited pseudo-activation energy of 11-14 kcal/mole computed from Connan's equation for the start of oil generation from kerogen is meaningless.-Author

Journal of Petroleum Geology↗
USGS2007

The influence of extractable organic matter on vitrinite reflectance suppression: A survey of kerogen and coal types

The vitrinite reflectance suppression literature shows that while bitumen impregnation of the vitrinite group is often invoked as a significant contributor to suppression, its existence is not often supported by petrological evidence. This study examines bitumen impregnation as a factor in vitrinite suppression by comparing the vitrinite reflectance of source rock and coal samples before and after solvent-extraction. Bitumen, often defined as organic matter soluble or extractable in certain organic solvents, should be removed by Soxhlet method solvent extraction using chloroform. Removing the extractable bitumen should restore the suppressed reflectance to its true higher value. However, the solvent extracted samples averaged 0.014% Rv less than that of the unextracted samples. We conclude from these results and from other published data that reflectance suppression by bitumen impregnation in the vitrinite maceral group, above the huminite stage of gelification, is seemingly a rare phenomenon and whose effect on suppressing vitrinite reflectance is typically negligible. ?? 2006.

International Journal of Coal Geology↗
USGS2006

Secondary gas emissions during coal desorption, Marathon Grassim Oskolkoff-1 Well, Cook Inlet Basin, Alaska: Implications for resource assessment

Cuttings samples of sub-bituminous humic coals from the Oligocene to Pliocene Tyonek Formation, Cook Inlet Basin, Alaska show secondary gas emissions whose geochemistry is consistent with renewed microbial methanogenesis during canister desorption. The renewed methanogenesis was noted after initial desorption measurements had ceased and a canister had an air and desorbed gas mixture backflow into the canister during a measurement. About a week after this event, a secondary emission of gas began and continued for over two years. The desorbed gas volume reached a new maximum, increasing the total from 3.3 to 4.9 litres, some 48% above the pre-contamination total volume. The gases released during desorption show a shift in the isotopic signature over time of methane from ??13CCH4 of -53.60 ??? and ??DCH4 of -312.60 ??? at the first day to ??13CCH4 of -57.06 ??? and ??DCH4 of -375.80 ??? after 809 days, when the experiment was arbitrarily stopped and the canister opened to study the coal. These isotopic data, interpreted using a Bernard Diagram, indicate a shift from a mixed thermogenic and biogenic source typical of natural gases in the coals and conventional gas reservoirs of the Cook Inlet Basin to a likely biogenic acetate-fermentation methane source. However, the appearance of CO2 during the renewed gas emissions with a ??13CCO2 of +26.08 to +21.72 ???, interpreted using the carbon isotope fractions found for acetate fermentation and CO2 reduction between CO2 and CH4 by Jenden and Kaplan (1986), indicates a biogenic CO2-reduction pathway may also be operative during renewed gas emission. Adding nutrients to the coal cuttings and canister water and culturing the microbial consortia under anaerobic conditions led to additional methane-rich gas generation in the laboratory. After this anaerobic culturing, ultraviolet microscopy showed that canister water contained common, fluorescent, rod-like microbes comparable to Methanobacterium sp. Scanning electron microscope investigations of the coal matrix showed several morphological types of microbes, including rod, cocci and spherical forms attached to the coal surface. These microbes apparently represent at least a portion of the microbial consortia needed to depolymerize coal, as well as to generate the observed secondary methane emission from the canister. The introduction of 48% more methane from secondary sources has a major impact on coal-bed methane resource assessments and also in determining the true, in-situ degree of methane saturation in coal-beds using isotherms. Canister and isotherm measurements that show "supersaturation" of methane may actually be the result of additional gases generated during secondary methanogenesis.

Bulletin of Canadian Petroleum Geology↗
USGS2006

Visual detection of gas shows from coal core and cuttings using liquid leak detector

Portions of core or cutting samples that have active gas shows can be identified by applying a liquid leak detector to the core surface. Although these gas shows can be caused by manmade changes to the coals' internal structure and surface of the core during the coring process, in many cases, the marked gas shows overlie changes in maceral composition, subtle fractures or coal, coal structure and so forth that seemingly are places where natural primary permeability is higher and gas shows would be favored. Given the limited time available for core description before a core is closed in a canister, using the liquid leak detector method to mark gas shows enhances core description by providing a photographic record of places of apparently increased gas flow likely related to enhanced coal permeability that cannot be easily detected otherwise.

Bulletin of Canadian Petroleum Geology↗
USGS2004

Formation of a paleothermal anomaly and disseminated gold deposits associated with the Bingham Canyon porphyry Cu-Au-Mo system, Utah

The thermal history of the Oquirrh Mountains, Utah, indicates that hydrothermal fluids associated with emplacement of the 37 Ma Bingham Canyon porphyry Cu-Au-Mo deposit extended at least 10 km north of the Bingham pit. An associated paleothermal anomaly enclosed the Barneys Canyon and Melco disseminated gold deposits and several smaller gold deposits between them. Previous studies have shown the Barneys Canyon deposit is near the outer limit of an irregular distal Au-As geochemical halo, about 3 km beyond an intermediate Pb-Zn halo, and 7 km beyond a proximal pyrite halo centered on the Bingham porphyry copper deposit. The Melco deposit also lies near the outer limit of the Au-As halo. Analysis of several geothermometers from samples collected tip to 22 km north of the Bingham Canyon porphyry Cu-Au-Mo deposit indicate that most sedimentary rocks of the Oquirrh Mountains, including those at the gold deposits, have not been regionally heated beyond the "oil window" (less than about 150??C). For geologically reasonable heating durations, the maximum sustained temperature at Melco, 6 km north of the Bingham pit, and at Barneys Canyon, 7.5 km north of the pit, was between 100??C and 140??C, as indicated by combinations of conodont color alteration indices of 1.5 to 2, mean random solid bitumen reflectance of about 1.0 percent, lack of annealing of zircon fission tracks, and partial to complete annealing of apatite fission tracks. The pattern of reset apatite fission-track ages indicates that the gold deposits are located approximately on the 120??C isotherm of the 37 Ma paleothermal anomaly assuming a heating duration of about 106 years. The conodont data further constrain the duration of heating to between 5 ?? 104 and 106 years at approximately 120??C. The ??18O of quartzite host rocks generally increases from about 12.6 per mil at the porphyry to about 15.8 per mil approximately 11 km from the Bingham deposit. This change reflects interaction of interstitial clays in the quartzite with circulating meteoric water related to the Bingham Canyon porphyry system. The ??18O and ??13C values of limestone vary with respect to degree of recrystallization and proximity to open fractures. Recrystallized limestone at the Melco and Barneys Canyon gold deposits has the highest ??18O values (about 30???), whereas limestone adjacent to the porphyry copper deposit has the lowest values (about 10???). The high ??18O values for the recrystallized limestone at Barneys Canyon and Melco strongly suggest that mineralization was related to low temperature fluids with exceptionally high ??18OH2O values such as could be derived from water in a crater lake of an active volcano. The age of formation of the gold deposits has been interpreted to range from Jurassic to Eocene. The mineralized rocks at the Barneys Canyon and Melco deposits are likely the same age as the geochemically similar deposits that are present in north-striking, late faults that cut the Bingham Canyon porphyry. The patterns of apatite and zircon fission-track data, conodont color alteration indices, solid bitumen reflectivity, stable isotope data, and mineral zoning are consistent with the gold deposits being genetically related to formation of the 37 Ma Bingham porphyry deposit. We interpret the disseminated gold mineralization to be related to collapse of the Bingham Canyon hydrothermal system in which isotopically heavy, oxidizing, acidic waters, possibly from an internally draining acidic crater lake, mixed with and were entrained into reduced gold-bearing meteoric water fluids in the collapsing main-stage hydrothermal system. Most of this fluid mixing and cooling was probably located close to the hydrologic interface between the sedimentary basement rocks and overlying volcanic rocks. ??2004 by Economic Geology.

Economic Geology↗
USGS2003

Coalbed gas in the Mecsek Basin, Hungary

Information about the presence and recovery of coalbed gas during underground mining and attempts to recover the gas as an energy source, plus new data about gas storage capacity, petrography, maturity, and other coal quality factors, indicate that the coals of the Mecsek Basin may contain large quantities of coalbed gas that is largely methane. Two preliminary estimates of the total gas content of the coalfield are 0.28e+11 m3 (almost 1 trillion cubic feet) and 1.13e+11 m3 (nearly 4 trillion cubic feet). Although much more information is needed about gas contents, permeabilities and other reservoir factors, the available geologic information may be sufficient to identify target areas for exploration. Efforts required to evaluate production potential are warranted. ?? 2003 Elsevier Science B.V. All rights reserved.

International Journal of Coal Geology↗
USGS2001

Deposition of sedimentary organic matter in black shale facies indicated by the geochemistry and petrography of high-resolution samples, blake nose, western North Atlantic

A transect of three holes drilled across the Blake Nose, western North Atlantic Ocean, retrieved cores of black shale facies related to the Albian Oceanic Anoxic Events (OAE) lb and ld. Sedimentary organic matter (SOM) recovered from Ocean Drilling Program Hole 1049A from the eastern end of the transect showed that before black shale facies deposition organic matter preservation was a Type III-IV SOM. Petrography reveals that this SOM is composed mostly of degraded algal debris, amorphous SOM and a minor component of Type III-IV terrestrial SOM, mostly detroinertinite. When black shale facies deposition commenced, the geochemical character of the SOM changed from a relatively oxygen-rich Type III-IV to relatively hydrogen-rich Type II. Petrography, biomarker and organic carbon isotopic data indicate marine and terrestrial SOM sources that do not appear to change during the transition from light-grey calcareous ooze to the black shale facies. Black shale subfacies layers alternate from laminated to homogeneous. Some of the laminated and the poorly laminated to homogeneous layers are organic carbon and hydrogen rich as well, suggesting that at least two SOM depositional processes are influencing the black shale facies. The laminated beds reflect deposition in a low sedimentation rate (6m Ma-1) environment with SOM derived mostly from gravity settling from the overlying water into sometimes dysoxic bottom water. The source of this high hydrogen content SOM is problematic because before black shale deposition, the marine SOM supplied to the site is geochemically a Type III-IV. A clue to the source of the H-rich SOM may be the interlayering of relatively homogeneous ooze layers that have a widely variable SOM content and quality. These relatively thick, sometimes subtly graded, sediment layers are thought to be deposited from a Type II SOM-enriched sediment suspension generated by turbidities or direct turbidite deposition.

Special Papers of the Geological Society of London↗
USGS1999

Fluid inclusion and vitrinite-reflectance geothermometry compared to heat-flow models of maximum paleotemperature next to dikes, western onshore Gippsland Basin, Australia

Nine basalt dikes, ranging from 6 cm to 40 m thick, intruding the Upper Jurassic–Lower Cretaceous Strzelecki Group, western onshore Gippsland Basin, were used to study maximum temperatures ( T max ) reached next to dikes. T max was estimated from fluid inclusion and vitrinite-reflectance geothermometry and compared to temperatures calculated using heat-flow models of contact metamorphism . Thermal history reconstruction suggests that at the time of dike intrusion the host rock was at a temperature of 100–135°C. Fracture-bound fluid inclusions in the host rocks next to thin dikes (<3.4 m thick) suggest T max systematically increases towards the dike margin to at least 500°C. The estimated T max next to the thickest dike (thickness ( D )=40 m) suggests an extended zone of elevated R v-r to at least a distance from the dike contact ( X ) of 60 m or at X / D >1.5, using a normalized distance ratio used for comparing measurements between dikes regardless of their thickness. In contrast, the pattern seen next to the thin dikes is a relatively narrow zone of elevated R v-r . Heat-flow modeling, along with whole rock elemental and isotopic data, suggests that the extended zone of elevated R v-r is caused by a convection cell with local recharge of the hydrothermal fluids . The narrow zone of elevated R v-r found next to thin dikes is attributed to the rise of the less dense, heated fluids at the dike contact causing a flow of cooler groundwater towards the dike and thereby limiting its heating effects. The lack of extended heating effects suggests that next to thin dikes an incipient convection system may form in which the heated fluid starts to travel upward along the dike but cooling occurs before a complete convection cell can form. Close to the dike contact at X / D <0.3, R v-r often decreases even though fluid inclusion evidence indicates that T max is still increasing. Further, fluid inclusion evidence indicates that the evolution of water vapor or supercritical fluids in the rock pores corresponds to the zone where R v-r begins to decrease. The generation of the water vapor or supercritical fluids near the dike contact seems to change vitrinite evolution reactions. These metamorphic conditions, closer to the dike than X / D =0.3 make vitrinite-reflectance unreliable as a geothermometer. The form of the R v-r profile, as it indicates T max , can be interpreted using temperature profiles estimated from various heat-flow models to infer whether the dike cooled by conduction, incipient convection, or a convection cell. A contact aureole that consists of decreasing R v-r or T max extending out to X / D ≥2 and that has a T contact ≫( T magma + T host )/2 appears to be a signature of simple conductive cooling. Incipient convection is indicated by a R v-r profile that decreases to background levels at X / D <1. A convection cell is indicated by a wave-like form of the R v-r profile and consistently high R v-r that may not decrease to background levels until beyond distances of X / D >1.5.

International Journal of Coal Geology↗
USGS1997

Depositional sequence stratigraphy and architecture of the cretaceous ferron sandstone: Implications for coal and coalbed methane resources - A field excursion

This Field Excursion will visit outcrops of the fluvial-deltaic Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale, known as the Last Chance delta or Upper Ferron Sandstone. This field guide and the field stops will outline the architecture and depositional sequence stratigraphy of the Upper Ferron Sandstone clastic wedge and explore the stratigraphic positions and compositions of major coal zones. The implications of the architecture and stratigraphy of the Ferron fluvial-deltaic complex for coal and coalbed methane resources will be discussed. Early works suggested that the southwesterly derived deltaic deposits of the the upper Ferron Sandstone clastic wedge were a Type-2 third-order depositional sequence, informally called the Ferron Sequence. These works suggested that the Ferron Sequence is separated by a type-2 sequence boundary from the underlying 3rd-order Hyatti Sequence, which has its sediment source from the northwest. Within the 3rd-order depositional sequence, the deltaic events of the Ferron clastic wedge, recognized as parasequence sets, appear to be stacked into progradational, aggradational, and retrogradational patterns reflecting a generally decreasing sediment supply during an overall slow sea-level rise. The architecture of both near-marine facies and non-marine fluvial facies exhibit well defined trends in response to this decrease in available sediment. Recent studies have concluded that, unless coincident with a depositional sequence boundary, regionally extensive coal zones occur at the tops of the parasequence sets within the Ferron clastic wedge. These coal zones consist of coal seams and their laterally equivalent fissile carbonaceous shales, mudstones, and siltstones, paleosols, and flood plain mudstones. Although the compositions of coal zones vary along depositional dip, the presence of these laterally extensive stratigraphic horizons, above parasequence sets, provides a means of correlating and defining the tops of depositional parasequence sets in both near-marine and non-marine parts of fluvial-deltaic depositional sequences. Ongoing field studies, based on this concept of coal zone stratigraphy, and detailed stratigraphic mapping, have documented the existence of at least 12 parasequence sets within the Last Chance delta clastic wedge. These parasequence sets appear to form four high frequency, 4th-order depositional sequences. The dramatic erosional unconformities, associated with these 4th-order sequence boundaries, indicate that there was up to 20-30 m of erosion, signifying locally substantial base-level drops. These base-level drops were accompanied by a basin ward shift in paleo-shorelines by as much as 5-7 km. These 4th-order Upper Ferron Sequences are superimposed on the 3rd-order sea-level rise event and the 3rd-order, sediment supply/accommodation space driven, stratigraphie architecture of the Upper Ferron Sandstone. The fluvial deltaic architecture shows little response to these 4th-order sea-level events. Coal zones generally thicken landward relative to the mean position of the landward pinch-out of the underlying parasequence set, but after some distance landward, they decrease in thickness. Coal zones also generally thin seaward relative to the mean position of the landward pinch-out of the underlying parasequence set. The coal is thickest in the region between this landward pinch-out and the position of maximum zone thickness. Data indicate that the proportion of coal in the coal zone decreases progressively landward from the landward pinch-out. The effects of differential compaction and differences in original pre-peat swamp topography have the effect of adding perturbations to the general trends. These coal zone systematics have major impact on approaches to exploration and production, and the resource accessment of both coal and coalbed methane.

Brigham Young University Geology Studies↗
USGS1996

A comparison of vitrinite reflectance measurements made on whole-rock and dispersed organic matter concentrate mounts

A comparison of mean-random vitrinite reflectance (R(v-r)) values calculated from measurements on polished whole-rock and on concentrates of dispersed organic matter (DOM) mounts of the same samples generally show little difference. Compared to measurements on DOM mounts, R(v-r) measurements by the same microscopist on corresponding whole-rock samples are up to a few tenths of a percent lower over the range of 0.6-3.2% R(v-r) and have a slightly higher standard deviation. Whole-rock mounts have an advantage over DOM mounts in the identification of first-cycle vitrinite and differentiation of solid bitumen from vitrinite.

Conference Paper↗