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

A high resolution Late Glacial to Holocene record of climatic and environmental change in the Mediterranean from Lake Ohrid (Macedonia/Albania)

Lake Ohrid (Macedonia/Albania) is one of the world’s oldest lakes and is renowned for its high degree of biological diversity. It is the target site for the ICDP SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) project, an international research initiative to study the links between geology, environment and the evolution of endemic taxa. In 2011 a 10-meter core was recovered from the western shore of Lake Ohrid adjacent to the Lini Peninsula

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

Improving spatial predictability of petroleum resources within the Central Tertiary Basin, Spitsbergen: a geochemical and petrographic study of coals from the eastern and western coalfields

Central Tertiary Basin (CTB) coals from a variety of palaeogeographic conditions within the Longyear and Verkhnij seams, were sampled to assess the relationship between the petroleum present, the remaining generation potential and coal geochemistry in order to improve the spatial predictability of petroleum resources within the basin. Vitrinite reflectance (VR) values from the CTB coals have been shown to be suppressed (Marshall et al., 2015a). This study attempts to quantify and correct for this suppression effect by applying the Lo (1993) method (LoVR), which uses Hydrogen Index (HI) values to modify VR data, and the coal Rank(Sr) scale of Suggate (2000, 2002), a technique not affected by suppression. In addition, the oil generation and expulsion thresholds for the CTB coals were investigated

Tropical peat surface oscillations are a function of peat condition at North Selangor peat swamp forest, Malaysia

Tropical peatland condition across southeast Asia is deteriorating as a result of conversion to agriculture and urban zones. Conversion begins by lowering the water table, which leads to peat decomposition, subsidence and increased risk of large-scale forest fires. Associated changes in mechanical peat properties impact the magnitude and timing of changes in peatland surface motion, making them a potential proxy for peatland condition. However, such a relationship is yet to be observed in a tropical peatland setting. This study aimed to establish whether patterns of tropical peatland surface motion were a function of peat condition at North Selangor Peat Swamp Forest in Selangor, Malaysia. Results showed that subsidence was greatest at fire-affected scrubland sites, whilst the lowest mean water table levels were found at smallholder oil palm sites. Peat condition and magnitude of tropical peat surface oscillation were significantly different between peat condition classes, whilst peat condition differed with depth. More degraded tropical peats with high bulk density throughout the peat profile due to high surface loading and low mean water table levels showed greater surface oscillation magnitudes. The dominant peat surface oscillation mechanisms present at all sites were compression and shrinkage from changes in water table level. Mean water table level and subsidence rate were related to surface oscillation magnitude. However further work towards measuring surface and within-water table range bulk densities and surface loading is required to better understand the controls on surface oscillation magnitudes

Conserved ancestral tropical niche but different continental histories explain the latitudinal diversity gradient in brush-footed butterflies.

The global increase in species richness toward the tropics across continents and taxonomic groups, referred to as the latitudinal diversity gradient, stimulated the formulation of many hypotheses to explain the underlying mechanisms of this pattern. We evaluate several of these hypotheses to explain spatial diversity patterns in a butterfly family, the Nymphalidae, by assessing the contributions of speciation, extinction, and dispersal, and also the extent to which these processes differ among regions at the same latitude. We generate a time-calibrated phylogeny containing 2,866 nymphalid species (~45% of extant diversity). Neither speciation nor extinction rate variations consistently explain the latitudinal diversity gradient among regions because temporal diversification dynamics differ greatly across longitude. The Neotropical diversity results from low extinction rates, not high speciation rates, and biotic interchanges with other regions are rare. Southeast Asia is also characterized by a low speciation rate but, unlike the Neotropics, is the main source of dispersal events through time. Our results suggest that global climate change throughout the Cenozoic, combined with tropical niche conservatism, played a major role in generating the modern latitudinal diversity gradient of nymphalid butterflies

Attenuation of TNT in seawater microcosms

The ability of two differing marine sediments (one clayey, the other sandy) to attenuate the explosive 2,4,6-trinitrotoluene (TNT), dissolved in intertidal seawater from the eastern English coast of the North Sea, was examined using aerobic microcosms. Analysis of the seawater from the microcosms revealed an initial sharp decline in TNT concentration with clayey sediment in both sterilized (to prevent microbial activity) and unsterilized microcosms. This effect did not occur to such a marked extent in similar sterile and non-sterile sandy sediment microcosms and was attributed mainly to sorption of TNT to the fine clay particles of the clayey sediment. As time progressed, the attenuation of TNT in microcosms containing either type of sediment was found to be less in those that had been sterilized compared with those where microbial action proceeded unhindered. Feeding the microcosms, (i.e. supplying extra carbon sources for the microbial communities), appeared to have a small, but perceptible, enhancing effect upon TNT dissipation. The attenuation of TNT was also measured in large microcosms containing 2.5 L of seawater and no sediment. Analysis of the seawater revealed a gradual decline in TNT concentration in non-sterile and fed microcosms compared to their sterile counterpart. Overall, this laboratory study showed that the attenuation of TNT is slow (half-life in seawater ca.1900 days; half-life sand sediment <700 days; half life in clay sediment 130 days) under conditions commonly encountered in coastal waters of the North Sea

10,000 years of sea-level change in the Thames Estuary

“Is the sea level rising in the Thames Estuary, and if so, by how much?” asks Dr Chris Vane who leads a number of projects investigating topics such as sea level change, biogeochemistry and sediment quality (pollution)

Simultaneous determination of PAHs and PCBs by GCMS analysis

A method for the simultaneous separation and identification of PAHs and PCBs by GCMS was successfully developed by this laboratory. The programming of associated software to identify and differentiate between similar compounds was an integral part of this development