Abstract We evaluated the unconventional hydrocarbon potential of the Holywell Shale Formation, a lateral equivalent of the Bowland Shale Formation deposited in the Blacon Basin. Two cores with Arnsbergian–Chokierian and Kinderscoutian (Namurian, Late Mississippian–Early Pennsylvanian) ages from the Ellesmere Port 1 borehole were sampled for palynological, stable isotope, Rock-Eval 6 pyrolysis and ichnofacies analyses. The study was designed to provide boundary conditions for parameters that are under-represented in the public domain and hamper accurate resource assessments: thermal maturity (through mean random vitrinite reflectance, R r), present-day organic matter content, kerogen type, original hydrogen index and original organic matter content. Our results show that the Arnsbergian Core 2 has been buried to a depth equivalent to the bottom of the oil window to the top of the gas window (% R r = 1.15%–1.29%). The Kinderscoutian Core 1 is too immature to have generated any natural gas (% R r = 0.91–1.03%). Furthermore, kerogen typing and ichnofacies analysis show that the Bowland Shale Formation is very heterogeneous, with organic matter originating from terrestrial and marine sources. Five palynofacies assemblages are described that range in basin setting from proximal and oxic to distal and anoxic with evidence of episodic connections to the open ocean. The combination of heterogeneity and low thermal maturity restricts the thickness of the Bowland Shale Formation in the Blacon Basin that is prospective for unconventional hydrocarbons. Our results show that these Carboniferous mudstones should not be treated as uniform units with uniform composition and maturity in basin modelling and resource estimates. This undoubtedly has repercussions for future exploration because the contrasting composition and density of the materials making up the Bowland Shale Formation may complicate extraction, while the thermal maturity window significantly narrows the prospective interval.

Abstract The Bowland sub-basin is a target for hydrocarbon exploration, but to a large extent it remains unexplored. To determine the economic potential of the Bowland sub-basin, it is important to identify the oceanographic processes involved in the deposition of the Bowland Shale Formation in the Late Mississippian (c. 330 Ma). Palaeoceanographic processes are known to be a major control on the development of hydrocarbon source rocks. This study investigates core (Preese Hall-1 and Becconsall-1Z) materials from the Upper Bowland Shale, and makes a comparison with previously published data (outcrop Hind Clough), all from the Bowland sub-basin, Lancashire, UK. The sedimentology and geochemistry of this formation were determined via a multi-technique approach including X-ray fluorescence, sedimentology, gamma-ray spectra, X-ray diffraction and Rock-Eval pyrolysis. Key trace metal abundances and enrichment factors were used to assess sediment provenance and to determine the bottom-water redox conditions during the deposition of the Upper Bowland Shale. Our results support interpretations of contemporaneous anoxia developing in bottom waters in at least three sites in the Bowland sub-basin. In a comparison with the Fort Worth Basin (Barnett Shale, USA), the Bowland sub-basin was apparently less restricted and deposited under a much higher mean sediment accumulation rate. Knowledge from this study will improve future resource estimates of the Bowland Shale Formation, and challenge the early assumptions that the Barnett Shale is an analogue of the Bowland Shale.

ABSTRACT Airborne radiometric (gamma-ray) data provide estimates of the concentrations of potassium (K), thorium (Th), and uranium (U) in soil, regolith, and bedrock. Radiometric data constitute an important source of geochemical information, commonly used in mineral exploration and for geological mapping of Earth and other planets. Airborne radiometric data have rarely been applied to the exploration and analyses of impact structures, in contrast with other conventional geophysical tools (e.g., gravimetry, magnetism, and seismic reflection/refraction). This work represents the first systematic survey of the K, Th, and U radiometric signatures of Australian impact structures, based on the continent-wide airborne radiometric coverage of Australia. We first formulated several hypotheses regarding the possible causes of formation of circular radiometric patterns associated with impact structures. Then, the radiometric signatures of 17 exposed impact structures in Australia were documented. Our observations confirmed the supposition that impact structures are commonly associated with circular radiometric patterns. We then selected the five structures with the most prominent circular radiometric patterns (Gosses Bluff, Lawn Hill, Acraman, Spider, and Shoemaker), and we discuss the possible origin of these anomalies. Based on these five case studies, we argue that such patterns result from either crustal deformation induced by the impact event and/or from postimpact superficial processes controlled by the crater topography. This work also suggests that airborne radiometric data may be useful, in combination with other geophysical tools, in the search for new possible impact structures.

With the myriad of measurement techniques and definitions of clays, the first question generally asked is “how much clay is there” in a sample? This often refers to the magnitude of a clay attribute in the sample and the answer to this question may vary depending on the measurement method. Does the method measure the clay-mineral type, the size distribution or mean size, the surface area, cation exchange capacity (CEC), rheology, or plasticity? Clay mineral type, particle size, and surface area are commonly used in mining operations to optimize oil-sand ore blending. In bitumen extraction and tailings management, where slurry behavior contributes to the process performance, propertiess uch as rheology and plasticity are also used. The previous chapters in the volume have introduced the various properties of clay particles and clay minerals. The present chapter describes the common methods of measuring clays and clay minerals in oil sands.

The clay minerals present in the oil-sands ore are responsible for some of the most challenging (and intriguing) processing behavior experienced on a routine basis in oil-sands surface mining. In previous chapters, significant details have been provided on how specific clay properties can give rise to changes in slurry rheology and interface phenomena. Because the bitumen extraction process relies heavily on manipulation of interfacial effects to enhance separation, changes in clay content in the ore, not surprisingly, can have a dramatic impact on the ability to process the material. This chapter provides an overview of the extraction process, the influence of clay minerals on bitumen recovery, and the challenges in reacting to changes in the ore clay content in a typical operation. The chapters that follow focus on the larger issue of tailings treatment to create a reclaimed landscape at the end of mine life.