The Geo-imaginaries of potential in Mexico's Burgos Basin

In this paper, we use the geo-imaginary analytic to show how actors utilized narratives of resource potential and speculative economic futures for the Burgos Basin in northeastern Mexico to affect a broader liberalization of the nation's hydrocarbon sector. Our research traces the history of the word “potential” as a discrete and repetitive rhetorical technique used variously to speculate on hydrocarbon production, economic development, regional energy development, and risks associated with the Burgos. We also identify an array of visualizations, what we refer to as ‘conjurings,’ used with narratives of potential to encourage investments in the Basin's development. These include: maps depicting Burgos geologic continuity with productive Texas fields, quantitative forecasts of growing production, visual depictions of private firms facilitating future production, and fracking as a necessary wedge to pry open the Burgos' unrealized potential. Finally, using governmentality, we link Burgos potentiality discourses to socio-political outcomes, including in the early 2000s, when the Basin was imagined as a way to counterbalance the skyrocketing costs of imported natural gas, continuing with the 2013–2014 Reforms, and into the post-Reform oil and gas conference spaces that facilitated financial investing opportunities. We also argue that the current administration leveraged anti-fracking discourse to reverse the liberalization of Mexico's hydrocarbon sector. By drawing together overlapping elements from scholarship into resources, speculation, and governmentality, and by parsing the ways that potential narratives and conjuring tools are deployed, this research contributes to ongoing debates in political geography around natural resources and the geopolitics of the subsurface.     

Fracture-fill calcite as a record of microbial methanogenesis and fluid migration: a case study from the Devonian Antrim Shale, Michigan Basin

The Devonian Antrim Shale is an organic‐rich, naturally fractured black shale in the Michigan Basin that serves as both a source and reservoir for natural gas. A well‐developed network of major, through‐going vertical fractures controls reservoir‐scale permeability in the Antrim Shale. Many fractures are open, but some are partially sealed by calcite cements that retain isotopic evidence of widespread microbial methanogenesis. Fracture filling calcite displays an unusually broad spectrum of δ¹³C values (+34 to ?41‰ PDB), suggesting that both aerobic and anaerobic bacterial processes were active in the reservoir. Calcites with high δ¹³C values (>+15‰) record cementation of fractures from dissolved inorganic carbon (DIC) generated during bacterial methanogenesis. Calcites with low δ¹³C values (13C values between ?10 and ?30‰ can be attributed to variable organic matter oxidation pathways, methane oxidation, and carbonate rock buffering. Identification of ¹³C‐rich calcite provides unambiguous evidence of biogenic methane generation and may be used to identify gas deposits in other sedimentary basins. It is likely that repeated glacial advances and retreats exposed the Antrim Shale at the basin margin, enhanced meteoric recharge into the shallow part of the fractured reservoir, and initiated multiple episodes of bacterial methanogenesis and methanotrophic activity that were recorded in fracture‐fill cements. The δ¹⁸O values in both formation waters and calcite cements increase with depth in the basin (?12 to ?4‰ SMOW, and +21 to +27‰ PDB, respectively). Most fracture‐fill cements from outcrop samples have δ¹³C values between ?41 and ?15‰ PDB. In contrast, most cement in cores have δ¹³C values between +15 and +34‰ PDB. Radiocarbon and ²³⁰Th dating of fracture‐fill calcite indicates that the calcite formed between 33 and 390 ka, well within the Pleistocene Epoch.     

The age of the manager is over? Shale gas fracking and the challenge to the post-political regime for English planning

Planning systems developed through the period of ‘normative’, ‘third way’ neoliberalism were critiqued as being ‘post-political’. Planning systems were developed that bypassed political conflicts through technocratic and consensus-seeking approaches following a so-called ‘end of history’ in which left/right ideological conflicts were deemed settled. Following the North Atlantic financial crisis of 2007/8 though, scholars have begun to question whether this is a suitable critique of planning, and state institutions more generally, as political and economic conditions shift. This paper examines a case of an exemplar post-political planning system: England. The paper identifies three key logics of a ‘post-political regime’ for planning: techno-managerialism, consensus and participation. Through an analysis of texts and interviews of contested planning decisions made over shale gas fracking sites, this paper shows a ‘post-political regime’ for planning facing a crisis of legitimacy as it is challenged by an anti-fracking movement and reactionary interventions from central government. The paper provides an institutional level analysis of the crisis of post-political planning, which has lost legitimacy amidst the slow collapse of normative neoliberalism.     

Pterygotid eurypterid chelicera from the Lower Devonian of Victoria

A single eurypterid (Arthropoda: Chelicerata) chelicera, assigned to Acutiramus sp. cf. A. bohemicus, is described from the Wilson Creek Shale, Turtons Creek inlier, north of Foster, Victoria, Australia. The specimen comprises the proximal portion of both rami. This pterygotid chelicera supports an Early Devonian (?Lochkovian) age for the stratum at this locality, by comparison with occurrences of A. bohemicus from the Czech Republic and closely related species in northern Gondwana.     

Geochemical fingerprinting of hydraulic fracturing fluids from Qusaiba Hot Shale and formation water from Paleozoic petroleum systems,Saudi Arabia

Provenance studies of produced water are essential to trace flow dynamics and reservoir compartmentalization in petroleum systems and to quantify fluid recovery rates from unconventional fracturing. Produced water from a hydraulically fractured well in the Qusaiba Hot Shale in the Northern Exploration Area, Saudi Arabia, was daily monitored and analyzed for water chemistry, and environmental (δ²H, δ¹³C, δ¹⁸O_H2O, δ¹⁸O_SO4, δ³⁴S_SO4, δ³⁷Cl, ⁸⁷Sr/⁸⁶Sr) and cosmogenic isotopes (³H, ¹⁴C, ³⁶Cl), to differentiate from reference fluids of supply water, fracturing fluids, and formation water from adjacent Paleozoic units. Initially, recovered water is composed of fracturing fluids and subsequently replaced by a homogeneous cut of pristine formation water. Formation water is composed of dominant meteoric water (approximately 84 vol%) and minor fossil evaporated seawater. The young ¹⁴C‐apparent age between 6000 and 6700 years BP and depleted δ¹⁸O/δ²H values for the meteoric component confirm the infiltration of surface water into the Qusaiba Hot Shale interval or adjacent units during the Early Holocene Pluvial Period under cooler and wetter climatic conditions than present, which suggest the presence of a very recent, dynamic hydraulic flow system. ³⁶Cl/Cl ratios between 102 × 10^?15 and 31 × 10^?15 are ambiguous and can be attributed to atmospheric recharge close to the coast, mixing of ³⁶Cl‐enriched Quaternary meteoric recharge with ³⁶Cl‐depleted fossil seawater, and/or hypogene production by U‐Th‐enriched host rock. Produced waters from Qusaiba Hot Shale are within the compositional range of Na‐Cl‐type formation water from Paleozoic reservoir units in northern Saudi Arabia with salinities from 30 000 to 130 000 mg l^?1. As a novel technological approach for exploration wells in Northern Saudi Arabia, multi‐isotopic methods were successfully implemented to quantify flowback volumes from hydraulic fracturing, and to fingerprint pristine formation water or pore water in Paleozoic systems on their provenance, residence time, migration pathways, and secondary alteration processes.     

The graptolite Glossograptus Emmons and its proximal structure

Ni Yunan & Cooper, R. A., 1994:03:28. The graptolite Glossograptus Emmons and its proximal structure. Alcheringa 18, 161–167. ISSN 0311-5518.

New specimens of Glossograptus acanthus from the Ningkuo Shale of China, preserved in relief, help to resolve the much debated problem of the structure of Glossograptus. A model for the proximal structure of the genus is proposed, based on the new material and on Finney's (1978) Athens Shale specimens. The model confirms that Glossograptus has homologous structure and development with Pseudisograptus, and isograptid development type is primitive for the group containing both genera. A cladogram is presented in which the suborder Glossograptina Jaanusson (with families Glossograptidae and Cryptograptidae) together with family Corynoididae Bulman are subsumed within a redefined family Glossograptidae.     

Early Triassic mastodonsaurids (Temnospondyli,Stereospondyli) from Western Australia,with remarks on mastodonsauroid palaeobiogeography

A newly discovered partial skull of a temnospondyl from the Early Triassic Blina Shale of the Erskine Range, Western Australia, is referred to the mastodonsaurid species Watsonisuchus aliciae. A partial skull described as ‘Parotosuchus’ sp. by Warren (1980) is also referred to W. aliciae. Both taxonomic assignments should be treated with caution because of the relatively poor state of preservation of the specimens. W. aliciae is the fourth temnospondyl species to be described from the Blina Shale. The worldwide distribution of mastodonsauroids at the base of the Triassic suggests a rapid phase of radiation and dispersal following the Permo-Triassic extinction event.     

The connectivity of pore space in mudstones: insights from high‐pressure Wood's metal injection,BIB‐SEM imaging,and mercury intrusion porosimetry

Study of the pore space in mudstones by mercury intrusion porosimetry is a common but indirect technique and it is not clear which part of the pore space is actually filled with mercury. We studied samples from the Opalinus Clay, Boom Clay, Haynesville Shale, and Bossier Shale Formations using Wood's metal injection at 316 MPa, followed by novel ion beam polishing and high‐resolution scanning electron microscopy. This method allowed us to analyze at high resolution which parts of a rock are intruded by the liquid alloy at mm to cm scale. Results from the Opalinus Clay and Haynesville Shale show Wood's Metal in cracks, but the majority of the pore space is not filled although mercury intrusion data suggests that this is the case. In the silt‐rich Boom Clay sample, the majority of the pore space was filled Wood's metal, with unfilled islands of smaller pores. Bossier Shale shows heterogeneous impregnation with local filling of pores as small as 10 nm. We infer that mercury intrusion data from these samples is partly due to crack filling and compression of the sample. This compaction is caused by effective stress developed by mercury pressure and capillary resistance; it can close small pore throats, prevent injection of the liquid metal, and indicate an apparent porosity. Our results suggest that many published MIP data on mudstones could contain serious artifacts and reliable metal intrusion porosimetry requires a demonstration that the metal has entered the pores, for example by Wood's metal injection, broad ion beam polishing, and scanning electron microscopy.