Investigating the Bowland Shale

The Bowland Shale (late Mississippian, early Carboniferous) has potential for the unconventional extraction of hydrocarbons in the UK and in equivalent successions that extend across Europe to the Lublin Basin, Poland. The Bowland Shale was deposited in a marine epicontinental seaway and in a basinal setting. This study seeks to characterise the controls (sedimentological, geochemical, biological, preservation) on the spatial and temporal distribution of organic matter in the Bowland Shale within the Craven Basin (UK) and link this to resource potential

Assessing low-maturity organic matter in shales using Raman spectroscopy : effects of sample preparation and operating procedure

Laser Raman spectroscopy is used to assess the thermal maturity of organic matter in sedimentary rocks, particularly organic-rich mudstones. However, discrepancies exist between quantified Raman spectral parameters and maturity values obtained by vitrinite reflectance. This has prevented the adoption of a standard protocol for the determination of thermal maturity of organic matter (OM) by Raman spectroscopy. We have examined the factors influencing the Raman spectra obtained from low-maturity OM in potential shale gas reservoir rocks. The inconsistencies in Raman results obtained are due to three main factors that are critically evaluated: (1) different operational procedures, including experiment setup and spectral processing methods; (2) different methods of sample preparation; (3) the analysis of diverse types of OM. These factors are scrutinized to determine the sources of inconsistency and potential bias in Raman results, and guidance is offered on the development of robust and reproducible analytical protocols. We present two new Raman parameters for un-deconvolved spectra named the DA1/GA ratio (area ratio of 1100–1400 cm−1/1550–1650 cm−1) and SSA (scaled spectrum area: sum of total area between 1100 and 1700 cm−1) that offer potential maturity proxies. An automated spreadsheet procedure is presented that processes raw Raman spectra and calculates several of the most commonly used Raman parameters, including the two new variables

Stream and slope weathering effects on organic-rich mudstone geochemistry and implications for hydrocarbon source rock assessment: a Bowland Shale case study

This study contributes to the exploration and quantification of the weathering of organic-rich mudstones under temperate climatic conditions. Bowland Shales, exposed by a stream and slope, were sampled in order to develop a model for the effects of weathering on the mudstone geochemistry, including major and trace element geochemistry, Rock-Eval pyrolysis and δ13Corg. Four weathering grades (I – IV) are defined using a visual classification scheme; visually fresh and unaltered (I), chemically altered (II, III) and ‘paper shale’ that typifies weathered mudstone on slopes (IV). Bedload abrasion in the stream exposes of visually fresh and geochemically unaltered mudstone. Natural fractures are conduits for oxidising meteoric waters that promote leaching at the millimetre scale and/or precipitation of iron oxide coatings along fracture surfaces. On the slope, bedding-parallel fractures formed (and may continue to form) in response to chemical and/or physical weathering processes. These fractures develop along planes of weakness, typically along laminae comprising detrital grains, and exhibit millimetre- and centimetre-scale leached layers and iron oxide coatings. Fracture surfaces are progressively exposed to physical weathering processes towards the outcrop surface, and results in disintegration of the altered material along fracture surfaces. Grade IV, ‘paper shale’ mudstone is chemically unaltered but represents a biased record driven by initial heterogeneity in the sedimentary fabric. Chemically weathered outcrop samples exhibit lower concentrations of both ‘free’ (S1) (up to 0.6 mgHC/g rock) and ‘bound’ (S2) (up to 3.2 mgHC/g rock) hydrocarbon, reduced total organic carbon content (up to 0.34 wt%), reduced hydrogen index (up to 58 mgHC/gTOC), increased oxygen index (up to 19 mgCO + CO2/gTOC) and increased Tmax (up to 11 °C) compared with unaltered samples. If analysis of chemically weathered samples is unavoidable, back-extrapolation of Rock-Eval parameters can assist in the estimation of pre-weathering organic compositions. Combining Cs/Cu with oxygen index is a proxy for identifying the weathering progression from fresh material (I) to ‘paper shale’ (IV). This study demonstrates that outcrop samples in temperate climates can provide information for assessing hydrocarbon potential of organic-rich mudstones

Mapping on the Edge: shoreline mapping for regulation and voluntary stewardship

Nothing generates conversations between landowners and local government like a map! Shoreline mapping is a crucial decision making tool for local governments and regulators. It provides information about appropriate location of shoreline infrastructure, such as docks, and informs landowners about the location of important natural transition areas between the land and the sea. Maps can also provide information that limits the activities of private landowners and as such can cause community conflict if they are inaccurate or unclear. Because mapping can be used to inform regulation, local governments often have different needs than scientists and NGOs, but there is no reason that mapping projects cannot accommodate multiple parties. The Islands Trust and Islands Trust Fund considered accuracy, methodology and budget when mapping eelgrass and forage fish habitats for the island in the Salish Sea and elected to work in partnership with two non-profit agencies – SeaChange Marine Conservation Society and the BC Marine Conservation and Research Society – to complete habitat mapping. Each of the project partners had specific and overlapping mapping needs. Collaboration resulted in cost-savings for all organizations as well as a dataset that accommodated multiple needs. The dataset is now one of the most requested data sets Islands Trust staff has seen in recent years. The mapping has been shared with other government agencies, NGOs and private industry and is being used to record habitat locations, plan and regulate shoreline uses, inform marine conservation areas and respond to emergencies. This Salish Sea Snapshot presentation will discuss the needs of local governments when mapping habitat, the advantages and challenges of collaboration with non-profits to complete mapping and ways to meet the needs of local governments, non-profit agencies and scientists to create a useful product

Linking Redox Processes and Black Shale Resource Potential

Black shales, such as the Mississippian (~330 Ma) Bowland Shale Formation, are targets for unconventional hydrocarbon exploration in the UK and in equivalents across Europe. Despite this interest, global decarbonisation, by definition, will either require; (1) complete replacement of natural gas with renewables and nuclear power generation, or; (2) moderate to limited natural gas use globally or locally, for example as a ‘bridge fuel’, as a source for hydrogen via steam reformation, or coupled to carbon capture and storage (CCS) technology. Any of these scenarios will increase the demand for transition metals such as V, Co and Ni, key elements used for energy storage and as catalysts in steam reformation. Black shales in general can host ore-grade enrichments in these metals, although the exact resource potential of UK Mississippian black shales remains unresolved. We integrate comprehensive sedimentological and geochemical data from three sections through the Bowland Shale in the Craven Basin (Lancashire, UK) to explore the links between controls on hydrocarbon and metal prospectivity. The Bowland Shale at these sites is a highly heterogeneous and complex ~120 m thick succession comprising carbonate-rich, siliceous and siliciclastic, argillaceous mudstones. These sedimentary facies developed in response to a combination of high-frequency (~111 kyr) sea level changes, fault activity at the basin margins and linkage with the nearby prograding Pendle delta system. Palaeoredox proxies such as Fe-speciation, redox-sensitive trace elements and S isotope analysis from extracted pyrite (δ34Spy) demonstrate intervals associated with metal enrichment were deposited under anoxic and at least intermittently euxinic (sulphidic) bottom water conditions. Trace element enrichment ‘V scores’ (sum of V+Mo+Se+Ni+Zn in ppm) indicate the greatest enrichments in these key transition metals and non-metals are associated with deposition under strongly sulphidic conditions during marine transgressions. V scores in these intervals are often >400 ppm and sometimes >1000 ppm. These bulk enrichments are comparable to stratiform low-grade ores such as the Upper Mudstone Member of the Devonian Popovich Formation (Nevada, USA). Hosts for these metals likely include solid sulphides such as pyrite, organic matter and possibly phosphates or carbonates. Critically, a process of switching between ferruginous and euxinic conditions in anoxic porewaters, termed ‘redox oscillation’, is recognised by a distinctive redox-sensitive trace element enrichment pattern, particularly competition between V and Ni metalation. Redox oscillation operated during periods of reduced sea level, where an increased supply of reactive Fe to the basin promoted development of intermittently ferruginous conditions in bottom waters and early diagenetic porewaters. Therefore the distribution of many redox-sensitive elements through the Bowland Shale is predictable. If these elements can be efficiently extracted from the mineral or organic hosts, UK Mississippian black shales may represent a significant resource. This work also improves understanding of the potential for co-extraction of metals during hydraulic fracturing, or during remediation of waste water. Future work will seek to understand which minerals or organic compounds host these redox-sensitive trace elements

Grain size and organic carbon controls polyaromatic hydrocarbons (PAH), mercury (Hg) and toxicity of surface sediments in the River Conwy Estuary, Wales, UK

The Conwy estuary was evaluated for sediment quality. Microtox bioassay revealed 38 of 39 sites were non-toxic. Hg ranged from 0.001 to 0.153 μg kg−1, mean 0.026 mg kg−1, Σ16 PAH from 18 to 1578 μg kg−1, mean 269 μg kg−1, Σ22 PAH, 18 to 1871 μg kg−1 mean to 312 μg kg−1, two sites had high perylene relative to ΣPAH. Σ22PAH correlated positively with TOC, clay and silt (R2 0.89, 0.92, 0.90) and negatively with sand. Multivariate statistics, delineated four spatial (site) and five variable (measurements) clusters. Spatial clustering relates to sediment grain size, in response to hydrodynamic processes in estuary; fine (clay to silt) sized sediments exhibit the highest Hg and PAH content, because these components partitioned into the fine fraction. Comparison to national and international environmental standards suggests Hg and PAH content of Conwy sediments are unlikely to harm ecology or transfer up into the human food chain

Origin and implications of early diagenetic quartz in the Mississippian Bowland Shale formation, Craven Basin, UK

Silica cementation exerts a key control on the compaction and geotechnical properties of mudstones, and by extension, the style of hydrocarbon and/or mineral systems present in a given sedimentary basin. Integrated microscopic and bulk geochemical observations demonstrate that siliceous mudstones in the Bowland Shale Formation, a target for UK shale gas extraction, exhibit abundant dispersed, discrete, μm-scale quartz cements, and exhibit silica enrichment (‘excess’) above a local detrital Si/Al threshold of 2.5. Dissolution of siliceous radiolarian tests during early diagenesis is identified as the main source of silica (opal A) required for quartz precipitation, either via opal CT or directly to quartz, and potentially generated as a product of anoxic marine ‘weathering’ (dissolution) of reactive silicates during early diagenesis. Excess silica correlates with free hydrocarbons (S1) normalised to total organic carbon (oil saturation index; OSI); we propose early diagenetic quartz precipitation suppressed pore collapse (‘buttress effect’), retaining the pore space capacity to host oil. Quartz precipitation was likely catalysed, for example via low porewater pH, elevated Al and/or Fe oxide content, and/or abundant labile organic matter. Juxtaposition of siliceous mudstones and mudstones lacking quartz cement indicates silica was immobile beyond the bed scale. Thus metre-scale siliceous packages likely represent more prospective units within the Bowland Shale (in terms of unconventional hydrocarbons), on the basis of early diagenetic biogenic-derived quartz cementation leading to improved hydrocarbon storage capacity coupled to enhanced brittleness. These findings are relevant for shale oil and shale gas systems, specifically where oil retained in pores subsequently cracks to generate gas. These findings also suggest the Bowland Shale is a sub-class of black shale, defined by the potential to host a relatively large volume of early diagenetic fluids, derived from anoxic bottom waters, which were potentially S- and/or metal-bearing. This is potentially relevant for understanding the genesis of adjacent and related Pb-Zn mineral deposits

RNA Sequencing of Carboplatin- and Paclitaxel-Resistant Endometrial Cancer Cells Reveals New Stratification Markers and Molecular Targets for Cancer Treatment.

Despite advances in surgical technique and adjuvant treatment, endometrial cancer has recently seen an increase in incidence and mortality in the USA. The majority of endometrial cancers can be cured by surgery alone or in combination with adjuvant chemo- or radiotherapy; however, a subset of patients experience recurrence for reasons that remain unclear. Recurrence is associated with chemoresistance to carboplatin and paclitaxel and consequentially, high mortality. Understanding the pathways involved in endometrial cancer chemoresistance is paramount for the identification of biomarkers and novel molecular targets for this disease. Here, we generated the first matched pairs of carboplatin-sensitive/carboplatin-resistant and paclitaxel-sensitive/paclitaxel-resistant endometrial cancer cells and subjected them to bulk RNA sequencing analysis. We found that 45 genes are commonly upregulated in carboplatin- and paclitaxel-resistant cells as compared to controls. Of these, the leukemia inhibitory factor, (LIF), the protein tyrosine phosphatase type IVA, member 3 (PTP4A3), and the transforming growth factor beta 1 (TGFB1) showed a highly significant correlation between expression level and endometrial cancer overall survival (OS) and can stratify the 545 endometrial cancer patients in the TCGA cohort into a high-risk and low-risk-cohorts. Additionally, four genes within the 45 upregulated chemoresistance-associated genes are ADAMTS5, MICAL2, STAT5A, and PTP4A3 codes for proteins for which small-molecule inhibitors already exist. We identified these proteins as molecular targets for chemoresistant endometrial cancer and showed that treatment with their correspondent inhibitors effectively killed otherwise chemoresistant cells. Collectively, these findings underline the utility of matched pair of chemosensitive and chemoresistant cancer cells to identify markers for endometrial cancer risk stratification and to serve as a pharmacogenomics model for identification of alternative chemotherapy approaches for treatment of patients with recurrent disease