Shale Exposure Research Articles

A note on the specimens of Kittonia hannae ‘hannai’  (Bacillariophyta) figured in Long et al. (1946)

In 1939, Lefébure & Chenevière described the Cretaceous fossil species Kittonia hannae Lefébure & Chenevière (1939: 23 pl. 1, fig. 3, see Sims & Williams 2022: fig. 8). The specimen figured was from the Moreno Shale deposit, California, USA, supplied by Dallas Hanna (1887–1970): “Moreno shale, Moreno Gulch in the Panoche Hills, Fresno County, California” […] “Sec. 6, T. 15 S., R. 12 E., M.D.B. & M., Fresno County, California” (Hanna 1934: 352, see also Hanna in Long et al. 1946: 91, Hanna 1927, Rampi 1940, Goudkoff 1945). Other specimens of Kittonia hannae were from another Moreno Shale exposure, “Sec. 24, T. 14, S., R. 11 E., Fresno County, California” (Hanna in Long et al. 1946: 93, Brigger & Hanna 1965: 4). A detailed discussion of the Moreno deposit can be found in Hanna (1927: 10), Long et al. (1946), Nikolaev et al. (2001) and Davies et al. (2012), and a review of the genus Kittonia was undertaken by Brigger & Hanna (1965).

Preservation and diagenesis of soft-bodied fossils and the occurrence of phosphate-associated rare earth elements in the Cambrian (Wuliuan) Spence Shale Lagerstätte

The Spence Shale Lagerstätte is a middle Cambrian (Miaolingian Series; Wuliuan Stage) fossil deposit in northern Utah and southern Idaho, USA. At present, it is known to preserve 89 species, from at least 10 phyla, of biomineralizing and soft-bodied taxa, and represents the only major Lagerstätte of Wuliuan age in Laurentia outside the Canadian Rockies. In addition to taxonomic diversity, the Spence Shale exposures represent a variety of depositional environments along a continental shelf, which have been affected by several diagenetic events, making it a compelling setting to improve our understanding of taphonomic and diagenetic pathways as they affect the broader Burgess Shale-type (BST) preservation. We present analyses of 28 specimens from six localities using scanning electron microscopy (SEM) and integrated energy dispersive X-ray spectrometry (EDS), together with comparisons of published data. Taxa are predominantly preserved as a combination of carbonaceous compressions, iron oxide and pyrite replacement, but eldoniids of the genus Eldonia consistently show enrichment in rare earth elements (REE). The REE, predominantly lanthanum and cerium, are enriched in the phosphate mineral monazite, which occurs in the inner coil of Eldonia ludwigi . This pattern, seen in all sampled Eldonia , differs from previous reports of REE association in BST preservation in being limited to one tissue type within a specific identifiable taxon. REE enrichment of tissues can occur during the lifetime of an individual or during fossilization, and we present both possible pathways along with an outline of taphonomic processes leading to the preservation of soft-bodied fossils from the Spence Shale. • Main preservation modes are carbonaceous compressions and iron oxides/pyrite. • Phosphatized Eldonia ludwigi have unique REE associations. • Preservation of tissue types is biased, as is found in other Paleozoic Lagerstätten.

Investigation of adsorption kinetics of CH4 and CO2 on shale exposure to supercritical CO2

The adsorption kinetics behaviors of CH4 and CO2 on shale are closely related to CO2 sequestration and enhanced shale gas recovery (CS-ESGR). To investigate the influence of supercritical CO2 (ScCO2) exposure on adsorption kinetics behaviors of CH4 and CO2 on shale, X-ray diffraction analysis, low-pressure N2 adsorption and adsorption kinetics experiment of CH4 and CO2 were conducted on raw and ScCO2-treated (10 day/16MPa/40 °C) shale collected from the Ordos Basin. Adsorption rates of CH4 and CO2 by shale were fitted by different adsorption kinetics models, and results indicate that Bangham adsorption (BA) model exhibits a better fitting effect (R2＞0.99) than Pseudo-first-order (PFO) and Pseudo-second-order (PSO) kinetic model and Elovich adsorption (EA) model. After ScCO2 exposure, the adsorption rate of CH4 and CO2 by shale decreased, which may be mainly caused by the decrease of high energy adsorption sites of shale. In addition, the adsorption rate of CO2 by shale is significantly higher than that of CH4, and the influence of pressure on the adsorption rates of CH4 and CO2 is remarkably different, suggesting that the CS-ESGR project should be divided into three stages: Fracturing-Recovery, Replacement-Recovery-Sequestration, and Replacement-Sequestration-Recovery. This study provides a reference for future optimization design of CS-ESGR.

Effect of supercritical CO2 extraction on CO2/CH4 competitive adsorption in Yanchang shale

Competitive adsorption characteristics of CO2/CH4 on shales before and after supercritical CO2 (ScCO2) extraction are closely related to CO2 injection in shale reservoir for CO2 sequestration and enhanced shale gas recovery (CS-ESGR). Using a self-developed PCTPro-type automatic high-pressure gas adsorption instrument, the adsorption behaviors of CH4, CO2 and their mixtures with different ratios were investigated on raw and ScCO2-treated (10 day/16 MPa/40 °C) shale collected from the Ordos Basin. The influences of ScCO2 extraction, pressure and CO2/CH4 cratios on adsorption capacity and selective adsorption factor of CO2/CH4 (SCO2/CH4) of shale have been analyzed. To interpret the experimental data, total organic carbon (TOC) analysis, X-ray diffraction (XRD) analysis, low-pressure gases adsorption and mercury intrusion were performed to evaluate the variations of mineral compositions and pore structure of shale exposure to ScCO2. It is found that SCO2/CH4 and the adsorption capacity of CO2/CH4 with different ratios decreased after ScCO2 extraction and are mainly attributable to the decrease of TOC, carbonates, clay minerals and specific surface area in ScCO2-treated shale. The feasibility of CS-ESGR cannot be affected by ScCO2 due to the values of SCO2/CH4 are always greater than 2.5 after ScCO2 extraction. Additionally, SCO2/CH4 decreased initially and then tended to be stable with increasing pressure, and it decreased slightly with increasing CH4 concentration in gas mixtures, suggesting that the reservoir pressure should be lowered before the injection of CO2 into shale reservoir, and the efficiency and engineering cost of CS-ESGR should be considered comprehensively. This study provides a reference for future optimization design of CS-ESGR.

Evaluation of the Hydrocarbon Potentials of Shale Exposures at Okpekpe in Edo North

This study evaluates the source rock characteristics of rock exposures along a newly exposed road cut in Okpekpe. An integrated technique of organic geochemical analysis and biostratigraphy evaluation were adopted to determine the source rock quality, Maturation index, kerogen types, depositional environment andsediment age.
 Results of organic geochemistry gave total organic carbon (TOC) value between 0.81 to 3.04 w.t% (2.08wt.% average) indicative of a good source potentials. The plot of Total Sulphur Content (TSC) against TOC suggests a transitional depositional environment for the samples while the plot of hydrogen index (HI) against oxygen index (OI) shows that the samples are capable of generating mixed type II/III kerogen.
 Palynological analysis revealed that the basal section of the exposure is characterized by the occurrences of typical and moderately rich Late Cretaceous – Early Tertiary palynomorphs. While the upper section is poorly rich in palynomorph abundance but with spot occurrences. The palynomophs asssemlages is of Late Maastrichtian - Early Paleocene and the outcrop is characterized by the presence of terrestrial pollens and spores indicating a continental to transitional depositional environment, typical of the Mamu Formation of the Anambra Basin.

CO2-water-shale interaction induced shale microstructural alteration

To better understand the CO2 enhanced shale gas recovery process, it is of great significance to investigate the CO2-water-shale interaction and its effect on the microstructural alteration in shale. To clarify the microstructural alteration of shale exposure to CO2-water at different CO2 pressures, X-ray diffraction analysis, low-pressure nitrogen gas adsorption (N2GA), nuclear magnetic resonance (NMR) and fractal analysis were carried on shale samples before and after pure water and CO2-water (PCO2 = 6, 10, 14 MPa; T = 45 °C) exposure. After CO2-water exposure, the contents of quartz in shale were increased, while the content of carbonate and clay minerals in shale were decreased with the increase of CO2 pressure. With the increase of CO2 pressure, the total specific surface area (TSSA) in shale were decreased with a maximum reduction of 29.40%, while the porosity was increased from 2.88% to a range of 2.93%-3.16%. The average pore size (Rave) in shale was also increased and the pore connectivity in shale was improved, micropores and mesopores in shale are gradually transferred to macropores. Both the pore surface fractal dimensions obtained from N2GA (DL1) and NMR (DN1), and the pore volume fractal dimensions obtained from N2GA (DL2) and NMR (DN2), were shown a reduction tendency with the increase of CO2 pressure, which reflected that the roughness and complexity of pore structure and morphology in shale decreased. The results indicated that the effect of super-critical CO2 (10 MPa, 14 MPa) on the pore structure alteration was more significant than that of sub-critical CO2 (6 MPa). The fractal dimensions calculated by N2GA and NMR tests had a good consistency, DL1, DN1, and DL2, DN2 shown positive correlations with TSSA and TPV (total pore volume), while shown negative correlations with Rave, which can be used to evaluate the gas adsorption and flow behaviors in shale, respectively.

Groundwater risk assessment investigations for oil shale exploitation in El-Lajjun area of central Jordan

Oil shales are sedimentary rocks that contain organic material in its inorganic matrix. The oil shale deposits of Jordan have been investigated since the 1960s. An extensive investigation studies have been commenced to evaluate the quality and quantity of these resources. In 2006, the government of Jordan invited pioneer companies in oil shale field to submit their proposal to utilize and develop the oil shale of Jordan using different extraction technologies. Jordan is considered one of the driest countries in the world, which poses an additional challenge for oil shale development, because a vast quantity of water is needed for this process. El-Lajjun study area is located in central Jordan; the oil shale in the study area was deposited in marine environment; it comprises massive beds of brown-black, kerogen-rich, bituminous chalky marl. Ten representative oil shale rock samples were collected for risk assessment investigations from different localities of oil shale exposures. A standardized laboratory Fischer assay test delivered oil shale characteristics. Sequential extraction was used to evaluate mobility and distribution of the trace elements Ti, V, Cr, Co, Zn, As, Zr, Cd, Pb, and U. Column leaching experiments were performed to simulate the leaching behavior of the above elements from oil shale and spent shale to evaluate the possible negative impact on groundwater in the study area. Results of sequential extraction indicate that concentration of trace elements and trace elements are richer in oil shale and in the spent shale compared to most rocks and soils. The concentrations in the leachate were below the maximum contaminant levels of the Environmental Protection Agency (EPA) and the Jordanian standards for drinking water. The significance of this study lies in that its utilizes for the first time the sequential extraction and column leaching techniques to investigate the Jordanian oil shale rocks.

Experimental study on tensile strength and acoustic emission characteristics of shale exposure to supercritical CO2

ABSTRACT The effect of supercritical CO2 on the mechanical properties of shale is a long-term process. To study the influence of supercritical CO2 on the tensile strength and acoustic emission characteristics of shale, the Brazilian splitting experiment equipped with a real-time monitoring of acoustic emission were conducted on the shale collected from Longmaxi formation in Sichuan Basin before and after supercritical CO2 treatment at different exposure times (0 day, 15 days, and 30 days) and a constant pressure (8 MPa) and temperature (40°C). The results show that the tensile strength of shale decreases and the failure deformation increases after supercritical CO2 treatment. The peak acoustic emission energy generated by the treated shale specimens in the process of Brazilian splitting experiment was significantly lower than that of the untreated, indicating that supercritical CO2 deteriorated the failure strength of the shale. The percentage of C element content has no obvious change, and the percentage of H element content decreased after supercritical CO2 treatment, which indicates that the supercritical CO2 fluid has negligible influence on organic matter in shale, while the water content of shale reduced. After supercritical CO2 treatment, the pore structure of shale measured by Poremaster-33 shows an increasing trend, the most probable pore size is shifted from 100–150 μm to 50–100 μm, and many new micro-pores (<20 μm) are generated in the shale. In addition, the formed CO2-water weak acid system in the process of supercritical CO2 treatment dissolves the carbonate and silicate in the shale measured by SEM/EDS. The main reasons for the decrease of tensile strength of shale after supercritical CO2 treatment can be attributed to the increased pore structure/volume and the dissolution of carbonate and silicate in the shale. The research results can provide reference for supercritical CO2 fluid exploitation of shale gas.

Geochemical record for the depositional condition and petroleum potential of the Late Cretaceous Mamu Formation in the western flank of Anambra Basin, Nigeria

Carbonaceous shale exposures of the Late Cretaceous Mamu Formation along Ifon-Uzebba road in western arm (Benin Flank) of Anambra Basin, southwestern Nigeria, were analyzed for bulk organic geochemical, molecular biological and poly-aromatic hydrocarbon (PAH) compositions to investigate the organic matter source, paleo-depositional condition, thermal maturity and petroleum potential of the unit. The bulk organic geochemistry was determined using Leco and Rock–Eval pyrolysis analyses while the biomarkers and PAH compositions were investigated using gas chromatography-mass spectrometer (GC–MS).The bulk organic geochemical parameters of the shale samples showed total organic carbon (TOC) (1.11–6.03 wt%), S2 (0.49–11.73 mg HC/g Rock), HI (38–242 mg HC/g TOC) and Tmax (425–435 °C) indicating good to excellent hydrocarbon source-rock. Typical HI-Tmax diagram revealed the shale samples mostly in the gas-prone Type III kerogen region with few gas and oil-prone Type II-III kerogen. The investigated biomarkers (n-alkane, isoprenoid, terpane, hopane, sterane) and PAH (alkylnaphthalene, methylphenanthrene and dibenzothiophene) indicated that the carbonaceous shales contain mix contributions of terrestrial and marine organic matter inputs that were deposited in a deltaic to shallow marine settings and preserved under relatively anoxic to suboxic conditions.Thermal maturity parameters computed from Rock–Eval pyrolysis, biomarkers (hopane, sterane) and PAH (alkylnaphthalene, alkylphenanthrene, alkyldibenzothiophene) suggested that these carbonaceous shales in Anambra Basin have entered an early-mature stage for hydrocarbon generation. This is also supported by fluoranthene/pyrene (0.27–1.12), fluoranthene/(fluoranthene + pyrene) (0.21–0.53) ratios and calculated vitrinite reflectance values (0.49–0.63% Ro) indicative that these shales have mostly reached early oil window maturity, thereby having low hydrocarbon source potential.

Element release and reaction-induced porosity alteration during shale-hydraulic fracturing fluid interactions

The use of hydraulic fracturing techniques to extract oil and gas from low permeability shale reservoirs has increased significantly in recent years. During hydraulic fracturing, large volumes of water, often acidic and oxic, are injected into shale formations. This drives fluid-rock interaction that can release metal contaminants (e.g., U, Pb) and alter the permeability of the rock, impacting the transport and recovery of water, hydrocarbons, and contaminants. To identify the key geochemical processes that occur upon exposure of shales to hydraulic fracturing fluid, we investigated the chemical interaction of hydraulic fracturing fluids with a variety of shales of different mineralogical texture and composition. Batch reactor experiments revealed that the dissolution of both pyrite and carbonate minerals occurred rapidly, releasing metal contaminants and generating porosity. Oxidation of pyrite and aqueous Fe drove precipitation of Fe(III)-(oxy)hydroxides that attenuated the release of these contaminants via co-precipitation and/or adsorption. The precipitation of these (oxy)hydroxides appeared to limit the extent of pyrite reaction. Enhanced removal of metals and contaminants in reactors with higher fluid pH was inferred to reflect increased Fe-(oxy)hydroxide precipitation associated with more rapid aqueous Fe(II) oxidation. The precipitation of both Al- and Fe-bearing phases revealed the potential for the occlusion of pores and fracture apertures, whereas the selective dissolution of calcite generated porosity. These pore-scale alterations of shale texture and the cycling of contaminants indicate that chemical interactions between shales and hydraulic fracturing fluids may exert an important control on the efficiency of hydraulic fracturing operations and the quality of water recovered at the surface.

A Fading Memory: The North Yorkshire Coastal Alum Industry in the Light of Recent Analytical Field Survey by English Heritage

For over 250 years from 1604, the North York Moors were the centre of the English alum industry. The principal use of alum was as a mordant to fix and enhance the colour of dyed cloth. It was made by quarrying, burning and steeping vast quantities of shale to produce an impure solution of aluminium sulphate; then, at alum houses, the liquor was concentrated by boiling, and an alkali added to form alum. The North Yorkshire quarries exploited both inland and coastal shale exposures, but the most successful quarry/alum house complexes (alum works) were situated on or near the coast. Even when operational, the latter had to contend with periodic infrastructure losses from landslips and cliff falls; with closure, they now form a diminishing archaeological resource steadily sliding into the sea. This paper reviews the present understanding of the industrial process in the light of recent analytical field survey by English Heritage of four hitherto poorly recorded works, three of which are coastal. In so doing, it highlights the disproportionate loss of certain classes of features at the coastal sites, and advocates the need to do more to compare the latter to their inland counterparts, to place the industry in its wider British and European context, and to examine it from an economic as well as a technological perspective.

Sedimentary rocks as sources of ancient organic carbon to the ocean: An investigation through Δ14C and δ13C signatures of organic compound classes

Chemical and isotopic variability of particulate organic carbon (POC) was examined in samples from the Santa Clara River watershed and adjacent shelf to investigate the processing of fossil POC derived from bedrock. The Santa Clara is a small coastal river that drains mountainous terrain in southern California, United States. Organic carbon in shale, river suspended sediment, and coastal marine sediment was separated into three operationally defined organic compound classes: total extractable lipids, acid hydrolyzable material, and the nonhydrolyzable residue. In all samples, the nonhydrolyzable fraction was dominant (∼50% of POC), while lipids and acid hydrolyzable moieties were relatively minor (≤22 and ≤13%, respectively). The Δ14C and δ13C signatures of the isolated fractions varied dramatically, not only across different sample types, but also for a given sample. At the shale exposure, low Δ14C values (&lt;−760‰) indicated dominance of ancient C in all three organic compound classes. In downstream samples, the extractable lipids displayed the lowest Δ14C values (&lt;−500‰), while the acid hydrolyzable fraction was predominantly modern (Δ14C &gt; −30‰). The nonhydrolyzable fraction displayed intermediate Δ14C values (&lt;−190‰) that increased steadily downstream with decreasing δ13C values (−22.2 to −25.0‰), possibly from mixing of shale and surface soil POC. Our results indicate that most of the fossil POC discharged by the Santa Clara is composed of non‐acid hydrolyzable material, but its elusive molecular structure and marine‐like δ13C signature may render its detection in the ocean difficult. In contrast, fossil lipids may be more amenable to detection if their resistant components (e.g., asphaltic material) are unique to crustal sources.

Fault-Controlled Hydrocarbon Pathways in the Monterey Formation, California

Field studies of low-permeability siliceous shale units of the Monterey Formation in the southern San Joaquin Valley and coastal California show evidence for fault control on hydrocarbon transport important for both migration and production. Shearing along preexisting discontinuities, such as bedding planes and joints, locally increases permeability in the sheared zone and surrounding fractured rock. As the rock is subjected to shear, it begins to systematically fragment and subsequently to brecciate, thereby creating interconnected voids for hydrocarbon transport. Petroleum-filled breccia zones are exposed in the Antelope Shale at Chico Martinez Creek on the northeastern flank of the Temblor Range near McKittrick, California. Breccia zones are found predominantly parallel to bedding in porcelanite units (4-10 cm thick) and are bounded above and below by siliceous shale beds (2-20 cm thick). Spacing between breccia zones is a function of lithology and diagenesis. This section of the Antelope Shale exposure originated as alternating layers of pure and terrigenous-rich diatomaceous sediment, in which these compositional variations influence the postdiagenetic material properties. Terrigenous-rich diatomite diagenetically alters to an incompetent siliceous shale (opal CT), whereas the cleaner sediments alter to a more brittle porcelanite (opal CT). Secondary fractures, or splay cracks, localize in the more brittle porcelanite in response to shearing along both bed-parallel lithologic discontinuities and bed-parallel fractures. With increased shearing, the fractured porcelanite subsequently evolves into brecciated fault zones. In the Chico Martinez Creek outcrop, individual breccia zones combine to make a petroleum-filled compound breccia zone approximately 10 m thick in which the original zones are partially obliterated by subsequent deformation. This outcrop-based conceptual model for the development of hydrocarbon pathways in the Monterey Formation is applied to the subsurface using formation microscanner (FMS) data and core. Bed-parallel breccia zones are identified in the Antelope Shale at Buena Vista Hills oil field. In the borehole image, the brecciated fault zone appears as unorganized patches of high and low resistivity with hints of bedding. At least one breccia zone identified in the borehole image correlates directly to hydrocarbon production as indicated by spinner flow-meter data. Although core recovery from fractured or brecciated zones is typically poor, there appears to be an association between fractures related to shearing processes and hydrocarbon occurrence in cores examined for this study. Oil-stained and brecciated fracture zones associated End page 1551---------------- with slip exist in Buena Vista Hills and other nearby fields producing from the Antelope Shale. Our multidisciplinary study, involving both geologic field data and borehole geophysical data, on the Monterey Formation reveals a critical relationship in which brittle fault zones provide permeable conduits for hydrocarbon transport and production.

Evaluation of previous remedial construction along the Duquesne Bluff

Abstract The Boulevard of the Allies is a major four lane roadway in Pittsburgh, Pennsylvania that is constructed atop a near vertical, 35 meter high rock slope known locally as the Duquesne Bluff. Stratigraphic relief observed on the bluff consists of alternating sequences of flat lying sedimentary deposits of sandstone, siltstone, shale, carbonaceous shale, claystone and limestone. Expsoure of alternating sequences of durable and less durable rock has resulted in differential weathering and the formation of precarious overhanging conditions. In the interest of motorist safety and roadway improvement, a major remedial program was undertaken by the Pennsylvania Department of Transportation (PennDOT) in the mid 1980s. Primary remedial activities included rock trimming, rock bolting, the construction of dental concrete buttressing for overhanging rock support and shotcrete slope facing to arrest continued weathering of less durable claystone and carbonaceous shale exposures. As part of a current roadway improvement project, PennDOT and their consultant, Gannett Fleming, Inc., are evaluating the performance of previous remedial construction and are developing preliminary alternatives for future remediation. This paper will discuss the slope geology, overall favorable performance of the previous remedial construction and unfavorable slope conditions that may have resulted from large scale trimming operations.

Stability analysis of rock slopes with the direct sliding blocks method

The Boulevard of the Allies is a major four lane roadway in Pittsburgh, Pennsylvania that is constructed atop a near vertical, 35 meter high rock slope known locally as the Duquesne Bluff. Stratigraphic relief observed on the bluff consists of alternating sequences of flat lying sedimentary deposits of sandstone, siltstone, shale, carbonaceous shale, claystone and limestone. Expsoure of alternating sequences of durable and less durable rock has resulted in differential weathering and the formation of precarious overhanging conditions. In the interest of motorist safety and roadway improvement, a major remedial program was undertaken by the Pennsylvania Department of Transportation (PennDOT) in the mid 1980s. Primary remedial activities included rock trimming, rock bolting, the construction of dental concrete buttressing for overhanging rock support and shotcrete slope facing to arrest continued weathering of less durable claystone and carbonaceous shale exposures. As part of a current roadway improvement project, PennDOT and their consultant, Gannett Fleming, Inc., are evaluating the performance of previous remedial construction and are developing preliminary alternatives for future remediation. This paper will discuss the slope geology, overall favorable performance of the previous remedial construction and unfavorable slope conditions that may have resulted from large scale trimming operations.

Bed Forms in Submarine Channels: Comparison of Ancient Examples from Greece with Studies of Recent Turbidite Systems

ABSTRACT Side-scan sonar observations have shown the presence of gravel waves, flute-like scours, and parallel erosional furrows in modern marine turbidity-current channels. Similar features are not well known from ancient rocks. Two Cenozoic sections of well-exposed turbidite channel fill in western Greece have been studied to determine why such features are difficult to recognize in the ancient geological record and which sedimentary facies are associated with large gravel bed forms. Gravel waves in ancient channel fills form in massive conglomerates with poor grading at the top of beds. They are found with sandstones of the high-density sandy turbidity current association. Series of erosional scours a few meters in size, similar to modern flute-like scours, have been mapped on the surface o debris-flow deposits in one ancient channel fill. Large gravel bed forms are difficult to recognize in the ancient geological record because of their scale and lack of distinctive features to aid lateral correlation across minor gaps in outcrop. Analogy with modern deposits and the sediment association suggest that deposition takes place in channels upslope from major sandy depocenters. The erosional features associated with modern gravel bed forms are difficult to recognize in the ancient record because of poor exposure of shales.

Size Characterization of Carbonaceous Particles Using a Lovelace Multijet Cascade Impactor / Parallel-Flow Diffusion Battery Serial Sampling Train

A serial sampling train consisting of a Lovelace multijet cascade impactor (LMJI) and a seven cell parallel-flow diffusion battery (PFDB) has been used to provide a comprehensive method for sizing aerosols with a wide size distribution ranging from less than 0.01 μm to over 10 μm. The fraction of the aerosol greater than 0.7 μm is collected by the impactor. The remaining fraction of the aerosol is sampled by the PFDB. Design of the PFDB is based on the theory of a screen-type diffusion battery. The concept of parallel flow is employed to provide a method for sampling aerosols that fluctuate too rapidly in concentration and size distribution to be measured by conventional methods. The LMJI/PFDB sampling system is useful for characterizing multimodel size distributions such as those that occur in ambient aerosols. It can also be used to determine the chemical composition of collected samples as a function of particle size. This sampling system has been used to size classify diesel and diesel-oil shale exposure atmospheres, and benzo(a)-pyrene-coated carbon black aerosols. The diffusion equivalent diameter (D de) of the diesel exhaust was 0.07–0.08 μm, and the oil-shale dust had a mass median aerodynamic diameter (MMAD) of 2.6–2.9 μm. The size distribution of the carbon black aerosol was bimodal, with the fine fraction having a D de of 0.2 μm, and the coarse fraction having a MMAD of 2.0 μm.

Morbidity survey of U.S. oil shale workers employed during 1948-1969.

The health status of 325 oil shale workers employed at the Anvil Points, Colorado, demonstration facility from 1948 to 1969 was evaluated. As a comparison population, 323 Utah coal miners frequency matched for age were studied. The prevalence of respiratory symptoms among oil shale workers who smoked were similar to the coal miners who smoked, although nonsmoking oil shale workers had fewer symptoms compared to nonsmoking coal workers. Four cases of skin cancers were found on the oil shale workers and eight cases in the controls. Similar numbers of nevi, telangiectasiae, possible pitch warts, pigment changes (solar/senile lentigo), and papillomata (seborrheic keratoses and skin tags) were seen in both groups, while actinic keratoses were more frequent in the oil shale workers. The prevalence of actinic keratoses was significantly associated with oil shale work after allowing for age, sun exposure, and other exposures. The prevalence of pulmonary cytology metaplasia was associated with years of production work in oil shale among both smokers and exsmokers. More of the oil shale workers had atypical cells in the urine, but the excess was mostly found among exsmokers. Although these workers had short-term and limited oil shale exposure work exposure, we recommend that medical surveillance of oil shale workers consider the skin, respiratory, and urinary systems for special observation.

Occurrence and Significance of Sedimentary Structures in Limestone Concretions, Greenhorn Formation, Northwestern Black Hills: ABSTRACT

It is now recognized that depositional environments of shales can be expanded beyond the phrase quiet-water deposition. One of the difficulties in delineating different depositional environments in fine-grained sediments is that descriptions of sedimentary structures in shales are not common. If the structures are preserved by some diagenetic process, then they can be more readily used in the interpretation of depositional environments. Diagenetic carbonate concretions that formed by the localized precipitation of cement in pore spaces of sediment would be expected to preserve original fabrics. Because of good exposure and greater resistance to weathering, concretions may exhibit features that are difficult to see in the less resistant surrounding shale. The Greenhorn Formation (Upper Cretaceous) north and west of the Black Hills is predominantly a shale with abundant limestone concretions. The concretions are generally restricted to certain zones. Shale exposures are generally unspectacular. The concretions, which are more resistant to weathering, contain a variety of physical and biogenic sedimentary structures. Commonly the structures are subtle. Polished slabs enhance or reveal structures not apparent in the field. Concretions from a given layer exhibit similar sedimentary structures. Parallel lamination is the most abundant physical sedimentary structure. Laminae range from 0.1 mm (.003 in.) to 1 cm (.4 in.) in thickness. They can be continuous with a constant thickness, continuous with a variable thickness, or discontinuous. Low angle ripple cross-stratification is present in some laminae. Graded bedding, cut-and-fill structures, and flame structures are also present. Biogenic structures include distinct burrows, burrow-disrupted layering, and thoroughly bioturbated textures. Depositional textures of the Greenhorn concretions include mudstone, wackestone, and packstone. Major grain types are inoceramid prisms and fragments, foraminifera, quartz, fish debris, and pellets. In some concretions, pellets are deformed indicating compaction occurred prior to cementation. The range of sedimentary structures, depositional textures, and abundance of quartz in Greenhorn concretions suggests variations in depositional conditions. Some laminae must have been deposited in quiet water with a current velocity close to zero while other laminae must have been deposited by currents of higher velocities. Cross-stratification is evidence that tractive currents were active in depositing and/or reworking the bottom sediments. The biogenic structures provide evidence of infaunal life and bioturbation. Where shale exposure is good, the same structures are observed in the shale as in the concretions. Therefore, structures in concretions are representative of the surrounding shale at that level. Concretions should not be ignored as a source of information regarding sedimentary structures. They can be valuable in the interpretation of paleoenvironments of shale. End_of_Article - Last_Page 507------------

AN UPPER VISÉAN ZAPHRENTOID FAUNA FROM THE YOREDALE BEDS OF NORTH-WEST YORKSHIRE

In the Yoredale Beds of North-west Yorkshire the shales immediately above the limestones often contain a fauna of Zaphrentoid phase. One such fauna was recorded by one of us (Hudson, 1925)1 from the three feet of shale overlying the Middle Limestone of Wensleydale. Further collections have been made from the exposure of this shale in Arn Gill, near Askrigg (Hudson, 1933, p. 429 and fig. 48).2 Most of the fossils are small simple corals whose septa meet axially and form a stereocolumn; the majority belong to two morphological groups with considerable variation in each. The following fauna was recorded in 1925 :— Cyathaxonia cornu Mich. Zaphrentis cf. ambigua mut. σ Vaughan Zaphrentis constricta Carruthers Zaphrentis cf. constricta (Densiphylloid variant) Zaphrentis eruca and variants (McCoy), abundant Zaphrentis sp. (cf. Densiphyllum costatum S. Smith, 1910, pl. I, fig. 11) Zaphrentis oystermouthensis Vaughan Similar faunas from comparable horizons were recorded by Garwood (1912) and Turner (1927) from the Westmorland Pennines, and by Carruthers (1922 and 1924) from Northumberland and Dunbar, Scotland. They have also been collected by one of us (R.G.S.H.) from the shales below the Five Yards Limestone of Wensleydale and from the shales, locally known as the Plate-with-Girdles, above and below the Five Yards Limestone of Upper Coverdale and Upper Wharfedale. The Plate-with-Girdles exposed in Slate Pit Beck and in Dowber Gill (Chubb and Hudson, 1925, p. 276) are perhaps the most fossiliferous of all shale exposures in the Yoredale Beds of Yorkshire. One of us (R.G.S.H.) has also re-examined the ...