• Effects of vegetation on bacterial communities, carbon and nitrogen in dryland soil surfaces: implications for shrub encroachment in the southwest Kalahari

      Thomas, Andrew D.; Tooth, Stephen; Wu, Li; Elliott, David R.; Aberystwyth University, Aberystwyth; Chinese Academy of Sciences, Wuhan; Wuhan University of Technology, Wuhan; University of Derby (Elsevier, 2020-10-09)
      Shrub encroachment is occurring in many of the world's drylands, but its impacts on ecosystem structure and function are still poorly understood. In particular, it remains unclear how shrub encroachment affects dryland soil surfaces, including biological soil crust (biocrust) communities. In this study, soil surfaces (0–1 cm depth) were sampled from areas of Grewia flava shrubs and Eragrostis lehmanniana and Schmidtia kalahariensis grasses in the southwest Kalahari during two different seasons (March and November). Our hypothesis is that the presence of different vegetation cover types (shrubs versus grasses) alters the microbial composition of soil surfaces owing to their contrasting microenvironments. The results showed that more significant differences in microclimate (light, soil surface temperatures) and soil surface microbial communities were observed between shrubs and grasses than between sampling seasons. Based on high-throughput 16S rRNA gene sequencing, our findings showed that approximately one third (33.5%) of the operational taxonomic units (OTUs) occurred exclusively in soil surfaces beneath shrubs. Soil surfaces with biocrusts in grass areas were dominated by the cyanobacteria Microcoleus steenstrupii, whereas the soil surfaces beneath shrubs were dominated by the proteobacteria Microvirga flocculans. Soil surfaces beneath shrubs are associated with reduced cyanobacterial abundance but have higher total carbon and total nitrogen contents compared to biocrusts in grass areas. These findings infer changes in the relative contributions from different sources of carbon and nitrogen (e.g. cyanobacterial and non-cyanobacterial fixation, plant litter, animal activity). The distinctive microbial composition and higher carbon and nitrogen contents in soil surfaces beneath shrubs may provide a positive feedback mechanism promoting shrub encroachment, which helps to explain why the phenomenon is commonly observed to be irreversible.
    • The eastern French Pyrenees: from mountain belt to foreland basin

      Satterfield, Dorothy; Rollinson, Hugh; Suthren, Roger; University of Derby (Wiley, 2019-12-09)
      The Pyrenees is a young mountain belt formed as part of the larger Alpine collision zone. This excursion explores the development of the Pyrenean Mountain Belt in southern France, from its early extensional phase in the mid‐Cretaceous and subsequent collisional phase, through its uplift and erosion in the Late Cretaceous and again in the Eocene, which led to the development of the Aquitaine‐Languedoc foreland basin. One of the complexities of the Pyrenean Belt is that thrusting, uplift and erosion during the Pyrenean orogeny exposed older Variscan basement rocks in the central core of the mountains, rocks which were metamorphosed during an earlier event in the late Carboniferous. Thus, this orogenic belt also tells the story of an earlier collision between Laurussia in the north and Gondwana in the south at c. 300 Ma, prior to the onset of the Pyrenean events at c. 100 Ma. Here we seek to unravel these two separate orogenic stories.
    • Surface stability in drylands is influenced by dispersal strategy of soil bacteria

      Elliott, David R.; Thomas, Andrew D.; Strong, Craig L.; Bullard, Joanna; Environmental sustainability Research Centre, University of Derby (American Geophysical Union (AGU), 2019-10-09)
      Microbial adaptations for survival and dispersal may directly influence landscape stability and potential for dust emission in drylands where biological soil crusts (biocrusts) protect mineral soil surfaces from wind erosion. In the Lake Eyre basin of central Australia we operated a wind tunnel on sandy soils and collected the liberated material, which was subjected to DNA sequencing to identify the microbial community composition. Microbial composition of entrained dust was compared with that of the source sand dune soil in addition to nearby claypan and nebkha soils, and water channels which together form a recycling sediment transport system. Wind was found to preferentially liberate 359 identified taxa from sand dunes whereas 137 identified taxa were found to resist wind erosion. Water channel communities included many taxa in common with the soil samples. We hypothesise that the ease with which soil microbes become airborne is often linked to whether the organism is adapted for dispersal by wind or vegetative growth, and that biocrust organisms found in water channels may sometimes use a fluvial dispersal strategy which exploits rare flooding events to rapidly colonise vast pans which are common in drylands. We explain likely geomorphic implications of microbial dispersal strategies which are a consequence of organisms engineering the environment to provide their particular needs. By identifying microbes fitting expectations for these dispersal strategies based on differential abundance analyses, we provide a new perspective for understanding the role of microbiota in landscape stability.
    • Basaltic maar-diatreme volcanism in the Lower carboniferous of the Limerick Basin (SW Ireland)

      Gernon, T. M.; Roberts, S.; Hewson, C.; Elliott, Holly; University of Southampton (Springer, 2015-04-16)
      Lead-zinc exploration drilling within the Limerick Basin (SW Ireland) has revealed the deep internal architecture and extra-crater deposits of five alkali-basaltic maar-diatremes. These were emplaced as part of a regional north-east south-west tectonomagmatic trend during the Lower Carboniferous Period. Field relationships and textural observations suggest that the diatremes erupted into a shallow submarine environment. Limerick trace element data indicates a genetic relationship between the diatremes and extra-crater successions of the Knockroe Formation, which records multiple diatreme filling and emptying cycles. Deposition was controlled largely by bathymetry defined by the surrounding Waulsortian carbonate mounds. An initial non-diatreme forming eruption stage occurred at the water-sediment interface, with magma-water interaction prevented by high magma ascent rates. This was followed by seawater incursion and the onset of phreatomagmatic activity. Magma-water interaction generated poorly vesicular blocky clasts, although the co-occurrence of plastically deformed and highly vesicular clasts indicate that phreatomagmatic and magmatic processes were not mutually exclusive. At a later stage, the diatreme filled with a slurry of juvenile lapilli and country rock lithic clasts, homogenised by the action of debris jets. The resulting extra-crater deposits eventually emerged above sea level, so that water ingress significantly declined, and late-stage magmatic processes became dominant. These deposits, largely confined to the deep vents, incorporate high concentrations of partially sintered globular and large ‘raggy’ lapilli showing evidence for heat retention. Our study provides new insights into the dynamics and evolution of basaltic diatremes erupting into a shallow water (20–120 m) submarine environment.
    • The significance of metasomatic alteration surrounding carbonatite complexes as a REE-enrichment indicator

      Broom-Fendley, S.; Wall, F.; Elliott, Holly; University of Exeter (Taylor and Francis, 2019-07-24)
    • Diatremes act as fluid conduits for Zn-Pb mineralization in the SW Irish Ore field

      Gernon, Thomas M.; Roberts, Stephen; Boyce, Adrian J.; Hewson, Chad; Elliott, Holly; University of Southampton (GeoScienceWorld, 2019-02-28)
      Irish-type mineralization is commonly attributed to fault-controlled mixing of a seawater-derived, sulfur-rich fluid and basement-derived, metal-rich fluid. However, maar-diatreme volcanoes discovered in close spatial and temporal association with Zn-Pb mineralization at Stonepark in the Limerick basin (southwest Ireland) bring a new dimension to established geologic models and may increase the deposit-scale prospectivity in one of the world’s greatest Zn-Pb districts. Stonepark exhibits many incidences of dolomitic black matrix breccias with associated Zn-Pb mineralization, the latter typically occurring within 150 m of the diatremes. Highly negative δ34S pyrite values within country rock-dominated black matrix breccias (–12 to –34‰) are consistent with sulfide precipitation from bacteriogenic sulfur reduction in seawater-derived brines. However, δ34S values of Zn-Pb sulfides replacing black matrix breccias (–10 to 1‰) reflect multiple sulfur sources. Diatreme emplacement both greatly enhanced country rock fracture permeability and produced conduits that are filled with porous volcaniclastic material and extend down to basement rock types. Our δ34S data suggest that diatremes provide more efficient fluid pathways for basement-derived fluids. The diatremes introduce another potential sulfur source and facilitate a greater input of metal-rich basement-derived hydrothermal fluid into the system compared to other Irish-type deposits such as Navan and Lisheen, evidenced by Stonepark’s more positive modal δ34S value of –4‰. Irish-type deposits are traditionally thought to form in association with extensional basement faults and are considered unrelated to extensive Carboniferous magmatism. Our results indicate that a direct link exists between diatreme volcanism and Zn-Pb mineralization at Limerick, prompting a reevaluation of the traditional Irish-type ore formation model, in regions where mineralization is spatially associated with volcanic pipes.
    • Fenites associated with carbonatite complexes: A review

      Wall, F.; Chakhmouradian, A.R.; Siegfried, P.R.; Dahlgren, S.; Weatherley, S.; Finch, A.A.; Marks, M.A.W.; Dowman, E.; Deady, E.; Elliott, Holly; et al. (Elsevier, 2017-12-11)
      Carbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE- and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE-enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.
    • Complex subvolcanic magma plumbing system of an alkali basaltic maar-diatreme volcano (Elie Ness, Fife, Scotland)

      Upton, B.G.J.; Ugra, R.; Yücel, C.; Taylor, R.N.; Elliott, Holly; University of Southampton (Elsevier, 2016-08-17)
      Alkali basaltic diatremes such as Elie Ness (Fife, Scotland) expose a range of volcanic lithofacies that points to a complex, multi-stage emplacement history. Here, basanites contain phenocrysts including pyrope garnet and sub-calcic augites from depths of ~60km. Volcanic rocks from all units, pyroclastic and hypabyssal, are characterised by rare earth element (REE) patterns that show continuous enrichment from heavy REE (HREE) to light REE (LREE), and high Zr/Y that are consistent with retention of garnet in the mantle source during melting of peridotite in a garnet lherzolite facies. Erupted garnets are euhedral and unresorbed, signifying rapid ascent through the lithosphere. The magmas also transported abundant pyroxenitic clasts, cognate with the basanite host, from shallower depths (~35–40km). These clasts exhibit wide variation in texture, mode and mineralogy, consistent with growth from a range of compositionally diverse melts. Further, clinopyroxene phenocrysts from both the hypabyssal and pyroclastic units exhibit a very wide compositional range, indicative of polybaric fractionation and magma mixing. This is attributed to stalling of earlier magmas in the lower crust — principally from ~22 to 28km — as indicated by pyroxene thermobarometry. Many clinopyroxenes display chemical zoning profiles, occasionally with mantles and rims of higher magnesium number (Mg#) suggesting the magmas were mobilised by juvenile basanite magma. The tuffs also contain alkali feldspar megacrysts together with Fe-clinopyroxene, zircon and related salic xenoliths, of the ‘anorthoclasite suite’ — inferred to have crystallised at upper mantle to lower crustal depths from salic magma in advance of the mafic host magmas. Despite evidence for entrainment of heterogeneous crystal mushes, the rapidly ascending melts experienced negligible crustal contamination. The complex association of phenocrysts, megacrysts and autoliths at Elie Ness indicates thorough mixing in a dynamic system immediately prior to explosive diatreme-forming eruptions.
    • Prospectivity mapping for high sulfidation epithermal porphyry deposits using an integrated compositional and topographic remote sensing dataset

      Ganas, Athanassios; Pope, Richard; Ferrier, Graham; University of Hull; National Observatory of Athens; University of Derby (Elsevier, 2019-02-26)
      The targeting and discovery of epithermal porphyry mineral deposits can be enhanced using a structured quantitative methodology to analyse the distribution of ore deposits and model their spatial association with exploration evidence providing improved understanding on the controls of ore deposition. A novel exploration tool integrating field and ASTER SWIR and TIR satellite imagery has been developed which provides an enhanced means of resolving surface expressions of the residual silica core of the lithocap. The alteration zones were clearly resolved by the remote sensing data and an intimate spatial relationship between high-grade altered rocks and topographic highs was identified at a number of locations. A Mineral Prospectivity Modelling (MPM) approach, parameterized by the results of the remote sensing study, using a GIS-based weighted linear combination implementation of a Multi-Criteria Evaluation approach and utilising a fuzzy Analytical Hierarchy Process to elucidate expert knowledge has been implemented to target high sulfidation epithermal porphyry deposits on the Island of Lesvos, Greece. The results from this integrated altitudinal-compositional modelling approach closely matched the hydrothermal alteration mapped in the field supporting the accuracy of this MPM approach.
    • Prospectivity Mapping for Epithermal Deposits of Western Milos Using a Fuzzy Multi Criteria Evaluation Approach Parameterized by Airborne Hyperspectral Remote Sensing Data

      Ferrier, Graham; Ganas, Athanassios; Pope, Richard; Miles, A. Jo; University of Hull; National Observatory of Athens; University of Derby; University of Bristol (MDPI, 2019-02-28)
      A Mineral prospectivity mapping (MPM) approach using a GIS-based weighted linear combination implementation of a Multi-Criteria Evaluation approach utilising a fuzzy Analytical Hierarchy Process to elucidate expert knowledge has been implemented to analyse the spatial distribution of epithermal deposits on the Island of Milos, Greece and model their association with exploration evidence data with the aim of providing insights into the controls on ore deposition. An integrated field and Digital Airborne Imaging Spectrometer (DAIS) hyperspectral and thermal multispectral airborne remote sensing dataset supported by field mapping and laboratory analyses, has been utilised to resolve hydrothermal alteration and parameterise the MPM. This study has highlighted the intimate spatial relationship between topographic highs and locations with high grade silicified alteration at a number of locations. The ability of high spatial resolution multispectral Thermal InfraRed (TIR) remote sensing imagery, integrated with topographic data, to resolve these silicified topographic highs provides an additional tool in the exploration of epithermal deposits. The spatial relationships between silicified lithocaps, high-grade altered rocks, faulting and topographic highs were utilised in the development of the MPM model. A close association between the modelled results and the hydrothermal alteration mapped in the field supports the accuracy of this MPM approach.
    • A further modification of Dioni’s mounting media to allow staining,clearing and mounting of Acari

      Chick, Andrew I. R.; University of Derby (2018-09-10)
      Modified Dioni’s media has previously been presented as an alternative to tradition Gum Chloral mounting media for microscopical specimens. This paper aims to explore a further modification of Dioni’s mounting media with the objective to provide a simple solution to clear, stain and mount Acari specimens in regions where obtaining Chloral Hydrate based media is problematic.
    • Bacterial and fungal communities in a degraded ombrotrophic peatland undergoing natural and managed re-vegetation

      Elliott, David R.; Caporn, Simon; Nwaishi, Felix; Nilsson, R. Henrik; Sen, Robin; Manchester Metropolitan University (Public Library of Science, 2015-05-13)
      The UK hosts 15–19% of global upland ombrotrophic (rain fed) peatlands that are estimated to store 3.2 billion tonnes of carbon and represent a critical upland habitat with regard to biodiversity and ecosystem services provision. Net production is dependent on an imbalance between growth of peat-forming Sphagnum mosses and microbial decomposition by microorganisms that are limited by cold, acidic, and anaerobic conditions. In the Southern Pennines, land-use change, drainage, and over 200 years of anthropogenic N and heavy metal deposition have contributed to severe peatland degradation manifested as a loss of vegetation leaving bare peat susceptible to erosion and deep gullying. A restoration programme designed to regain peat hydrology, stability and functionality has involved re-vegetation through nurse grass, dwarf shrub and Sphagnum re-introduction. Our aim was to characterise bacterial and fungal communities, via high-throughput rRNA gene sequencing, in the surface acrotelm/mesotelm of degraded bare peat, long-term stable vegetated peat, and natural and managed restorations. Compared to long-term vegetated areas the bare peat microbiome had significantly higher levels of oligotrophic marker phyla (Acidobacteria, Verrucomicrobia, TM6) and lower Bacteroidetes and Actinobacteria, together with much higher ligninolytic Basidiomycota. Fewer distinct microbial sequences and significantly fewer cultivable microbes were detected in bare peat compared to other areas. Microbial community structure was linked to restoration activity and correlated with soil edaphic variables (e.g. moisture and heavy metals). Although rapid community changes were evident following restoration activity, restored bare peat did not approach a similar microbial community structure to non-eroded areas even after 25 years, which may be related to the stabilisation of historic deposited heavy metals pollution in long-term stable areas. These primary findings are discussed in relation to bare peat oligotrophy, re-vegetation recalcitrance, rhizosphere-microbe-soil interactions, C, N and P cycling, trajectory of restoration, and ecosystem service implications for peatland restoration.
    • Niche partitioning of bacterial communities in biological crusts and soils under grasses, shrubs and trees in the Kalahari

      Elliott, David R.; Thomas, Andrew David; Hoon, Steve R.; Sen, Robin; Manchester Metropolitan University (Springer, 2014-04-06)
      The Kalahari of southern Africa is characterised by sparse vegetation interspersed with microbe-dominated biological soil crusts (BSC) which deliver a range of ecosystem services including soil stabilisation and carbon fixation. We characterised the bacterial communities of BSCs (0–1 cm depth) and the subsurface soil (1–2 cm depth) in an area typical of lightly grazed Kalahari rangelands, composed of grasses, shrubs, and trees. Our data add substantially to the limited amount of existing knowledge concerning BSC microbial community structure, by providing the first bacterial community analyses of both BSCs and subsurface soils of the Kalahari region based on a high throughput 16S ribosomal RNA gene sequencing approach. BSC bacterial communities were distinct with respect to vegetation type and soil depth, and varied in relation to soil carbon, nitrogen, and surface temperature. Cyanobacteria were predominant in the grass interspaces at the soil surface (0–1 cm) but rare in subsurface soils (1–2 cm depth) and under the shrubs and trees. Bacteroidetes were significantly more abundant in surface soils of all areas even in the absence of a consolidated crust, whilst subsurface soils yielded more sequences affiliated to Acidobacteria, Actinobacteria, Chloroflexi, and Firmicutes. The common detection of vertical stratification, even in disturbed sites, suggests a strong potential for BSC recovery after physical disruption, however severe depletion of Cyanobacteria near trees and shrubs may limit the potential for natural BSC regeneration in heavily shrub-encroached areas.
    • The influence of trees, shrubs, and grasses on microclimate, soil carbon, nitrogen, and CO2 efflux: Potential implications of shrub encroachment for Kalahari rangelands.

      Thomas, Andrew David; Elliott, David R.; Dougill, Andrew John; Stringer, Lindsay Carman; Hoon, Stephen Robert; Sen, Robin; Aberystwyth University; University of Derby; University of Leeds; Manchester Metropolitan University; et al. (Wiley, 2018-02-24)
      Shrub encroachment is a well‐documented phenomenon affecting many of the world's drylands. The alteration of vegetation structure and species composition can lead to changes in local microclimate and soil properties which in turn affect carbon cycling. The objectives of this paper were to quantify differences in air temperatures, soil carbon, nitrogen, and CO2 efflux under trees (Vachellia erioloba), shrubs (Grewia flava), and annual and perennial grasses (Schmidtia kalahariensis and Eragrostis lehmanniana) collected over three seasons at a site in Kgalagadi District, Botswana, in order to determine the vegetation‐soil feedback mechanism affecting the carbon cycle. Air temperatures were logged continuously, and soil CO2 efflux was determined throughout the day and evening using closed respiration chambers and an infrared gas analyser. There were significant differences in soil carbon, total nitrogen, CO2 efflux, light, and temperatures beneath the canopies of trees, shrubs, and grasses. Daytime air temperatures beneath shrubs and trees were cooler compared with grass sites, particularly in summer months. Night‐time air temperatures under shrubs and trees were, however, warmer than at the grass sites. There was also significantly more soil carbon, nitrogen, and CO2 efflux under shrubs and trees compared with grasses. Although the differences observed in soils and microclimate may reinforce the competitive dominance of shrubs and present challenges to strategies designed to manage encroachment, they should not be viewed as entirely negative. Our findings highlight some of the dichotomies and challenges to be addressed before interventions aiming to bring about more sustainable land management can be implemented.
    • Post-feeding activity of Lucilia sericata (Diptera: Calliphoridae) on common domestic indoor surfaces and its effect on development.

      Robinson, Louise; Bryson, David; Bulling, Mark T.; Sparks, N.; Wellard, K. S.; University of Derby (Elsevier, 2018-03-13)
      Developmental data of forensically important blowflies used by entomologists to estimate minimum post mortem interval (mPMI) are established under controlled laboratory conditions for various temperature ranges throughout the stages of egg, 1st-3rd instar, puparia, and adult fly emergence. However, environmental conditions may influence the patterns of development and behaviour of blowflies, potentially impacting on these established development rates. Previous studies investigating indoor colonisation have focused on the delay to oviposition, with behaviour during the post-feeding phase in this setting often overlooked. The environment in which third instar larvae disperse when searching for a pupariation site may vary drastically at both outdoor and indoor scenarios, influencing the activity and distance travelled during this phase and possibly affecting developmental rates. This study investigated the effect of eight common domestic indoor surfaces on dispersal time, distance travelled, and behaviour of post-feeding Lucilia sericata as well as any resulting variation in development. It was found that pupariation and puparia length within a pupariation medium of sawdust (often used in laboratory settings) produced comparable results with that of carpeted environments (those deemed to be 'enclosed'). Non-carpeted environments (those which were 'exposed') produced a delay to pupariation likely due to increased activity and energy expenditure in searching for pupariation sites which enabled burial. In addition, the observed speed of travel during dispersal was seen via time lapse photography to be greater within 'exposed' conditions. Larvae which dispersed upon burnt laminate flooring were observed to travel faster than in all other conditions and showed the only significant variation (P=0.04) in the day of emergence in comparison to the control condition of sawdust. This study has demonstrated that wandering phase activity is affected by the environmental surface which has potential implications for estimating both the distance travelled by dispersing larvae in indoor conditions and with further research, may be a consideration in mPMI calculations.
    • Pseudoscorpions, an understudied and ideal microscopic study organism.

      Chick, Andrew I. R.; Andrews, Liam; University of Derby (Quekett Microscopical Club, 2017)
    • Apis mellifera (Linnaeus, 1761) (Hymenoptera: Apidae) on carrion, a note of the behaviour and a review of the literature.

      Chick, Andrew I. R.; Dye, Alex; University of Derby; Rothamsted Research (Andrew Smith Print Ltd., 2017-11-25)
      The Honeybee Apis mellifera (Linnaeus, 1761) traditionally feeds on the nectar of flowers (Núñez, 1977). A number of workers of A. mellifera were observed on whole pig carrion in woodland in Riseholme Lincoln (Grid reference SK978754) on 10 of October 2017. This paper aims to look at this odd behaviour in context of the literature.
    • Creating three dimensional, orientable, temporary invertebrate slides for photomicrography.

      Chick, Andrew I. R.; University of Derby (The Amateur Entomologists' Society, 2017-09)
    • Insect microscopy.

      Chick, Andrew I. R.; University of Derby (Crowood Press, 2016-08-26)