Middle Coal Measures Research Articles

X-ray microtomography of the late Carboniferous whip scorpions (Arachnida, Thelyphonida) Geralinura britannica and Proschizomus petrunkevitchi

Whip scorpions (Thelyphonida) and schizomids (Schizomida) are closely related arachnid orders, whose low species diversity compared to other arachnid groups is reflected in a limited fossil record. Here we investigate two key fossil whip scorpions from the British Middle Coal Measures of Coseley, Staffordshire (late Carboniferous, c. 315 Ma), UK, using X-ray microtomography, and incorporate the taxa into an updated arachnid phylogeny. Geralinura brittanica Pocock, 1911 is an unequivocal whip scorpion, whose pedipalps are closer to the modern condition than previously assumed. The trochanter bears a dorsal flange with prodorsal teeth, and the whole pedipalp is rendered subchelate by the presence of at least a patellar apophysis. These results suggest a high degree of stasis in whip scorpions since the late Carboniferous, and the genus Geralinula Scudder, 1884 is within the crown-group; i.e. the extant family Thelyphonidae. Proschizomus petrunkevitchi Dunlop and Horrocks, 1996 lacks median eyes, a character shared with Schizomida, but unlike schizomids the pedipalp also has patellar and tibial apophyses; albeit with the appendage articulating at an angle of c. 45° rather than articulating horizontally as in living whip scorpions, or vertically as in schizomids. Our phylogeny refutes a previous hypothesis that P. petrunkevitchi is a stem-schizomid, and places it among the whip scorpions instead. However, the species may have branched early from the whip scorpion lineage, and thus its morphology might reflect a plesiomorphic arrangement in which the pedipalps were transitioning from a more leg-like to a fully raptorial and claw-like set of prey-catching appendages.

High selenium in the Carboniferous Coal Measures of Northumberland, North East England

The Carboniferous Lower and Middle Coal Measures coals of the Northumberland Coalfield are anomalously rich in selenium (Se) content (up to 62 ppm) compared to the averages for the common UK and worldwide coals. As well as posing an environmental toxicity threat, Se is now regarded as an important resource for alloys, photovoltaic products and nanotechnologies, and high Se coals in North East England offer an opportunity to assess the Se means of occurrence, origins, transport mechanisms and enrichment in coals. At least two generations of pyrite host high Se in the sampled coal seams: microbial-formed disseminated pyrite (both cubic and framboidal in habit) and later cleat-filling pyrite, identified by petrographic observations, laser ablation methods and sulphur isotope compositions. There is a notable Se enrichment of up to 250 ppm in later formed cleat-filling pyrite. Trace element enrichment may have been sourced and influenced by seawater distribution during diagenesis, and localised dykes and deformation may have acted as an enrichment mechanism for sampled seams in the region. The high Se coals in Northumberland may provide a potential E tech element source and should be considered and carefully managed as coal mining and production are reduced in the area. The study also highlights the nature of Se enrichment in pyritic coals affected by cleat formation and multiple episodes of mineralisation, important as critical element demand continues to increase worldwide.

The ontogeny of the 300 million year old xiphosuran Euproops danae (Euchelicerata) and implications for resolving the Euproops species complex.

Xiphosurans have often been considered as archaic appearing cheliceratan arthropods, with a rich fossil record. We describe here parts of the post-embryonic ontogeny of the 300 million year old xiphosuran Euproops danae (Xiphosura sensu stricto, Euchelicerata), from the Mazon Creek Lagerstätte (Upper Carboniferous), USA. Recently, the ontogeny of a closely related species, Euproops sp. from the Upper Carboniferous Piesberg quarry, Osnabrück, Germany (informally called 'Piesproops'), has been reconstructed. This analysis has drawn characters into question that were used to differentiate E. danae from another species occurring at the same time, Euproops rotundatus from the British Middle Coal Measures. More precisely, early post-embryonic stages of Piesproops resemble E. danae; later stages resemble E. rotundatus. Based on this earlier study, the here-described reinvestigation of E. danae has been performed as the ontogenetic sequence itself may yield more reliable characters for differentiating species of Euproops. We could identify eight different growth stages for E. danae. This ontogenetic sequence shows a comparable growth to that of Piesproops, but differs markedly in the development of the opisthosomal flange. This character may serve as a basis for reliably differentiating these species. Additionally, analysing the ontogeny of further species may offer the basis for identifying heterochronic shifts in the evolution of xiphosurans.

The phylogeny of fossil whip spiders

BackgroundArachnids are a highly successful group of land-dwelling arthropods. They are major contributors to modern terrestrial ecosystems, and have a deep evolutionary history. Whip spiders (Arachnida, Amblypygi), are one of the smaller arachnid orders with ca. 190 living species. Here we restudy one of the oldest fossil representatives of the group, Graeophonus anglicus Pocock, 1911 from the Late Carboniferous (Duckmantian, ca. 315 Ma) British Middle Coal Measures of the West Midlands, UK. Using X-ray microtomography, our principal aim was to resolve details of the limbs and mouthparts which would allow us to test whether this fossil belongs in the extant, relict family Paracharontidae; represented today by a single, blind species Paracharon caecus Hansen, 1921.ResultsTomography reveals several novel and significant character states for G. anglicus; most notably in the chelicerae, pedipalps and walking legs. These allowed it to be scored into a phylogenetic analysis together with the recently described Paracharonopsis cambayensis Engel & Grimaldi, 2014 from the Eocene (ca. 52 Ma) Cambay amber, and Kronocharon prendinii Engel & Grimaldi, 2014 from Cretaceous (ca. 99 Ma) Burmese amber. We recovered relationships of the form ((Graeophonus (Paracharonopsis + Paracharon)) + (Charinus (Stygophrynus (Kronocharon (Charon (Musicodamon + Paraphrynus)))))). This tree largely reflects Peter Weygoldt’s 1996 classification with its basic split into Paleoamblypygi and Euamblypygi lineages; we were able to score several of his characters for the first time in fossils. Our analysis draws into question the monophyly of the family Charontidae.ConclusionsOur data suggest that Graeophonus is a crown group amblypygid, and falls within a monophyletic Paleoamblypgi clade, but outside the family Paracharontidae (= Paracharonopsis + Paracharon). Our results also suggest a new placement for the Burmese amber genus Kronocharon, a node further down from its original position. Overall, we offer a broad phylogenetic framework for both the fossil and Recent whip spiders against which future discoveries can be tested.

British Pennsylvanian (Carboniferous) coal-bearing sequences: where is the time?

Abstract The Lower and Middle Coal Measures of Langsettian (Westphalian A) and Duckmantian (Westphalian B) age (together equals Bashkirian in part) in Britain comprise an alternation of clastic sediments and coal deposited on coastal and alluvial plains over a period of 2–3.5 million years, depending on which time scale is accepted. In both the Pennine and South Wales Basins there are no obvious unconformities. Many of the clastic sequences show evidence of rapid sedimentation (burial of trees, bivalve escape burrows) that may suggest that a significant amount of time is taken up during the peat-forming intervals. Thickness data from a range of boreholes that record continuous sections through this time period were collated. Coal and sediment thicknesses, as well as coal to sediment ratios, are compared both within and across the basins. Data on the coals has allowed consideration of the time taken to deposit the peats. This work considers the compaction of the peat to coal, as well as a range of peat accumulation rates. Assuming the largest de-compaction rates and slowest accumulation rates of the coal formation, less than 50% of the allocated time can be accounted for. In addition however, calculations suggest that peat formation accounts for less than 25% of the total time taken for sediment accumulation. It is suspected that there are major time gaps in the sequences, most probably occurring between seat-earths and coal and within the coals, and it is believed that this finding has significance for the debate over short-term climate changes in the Carboniferous and the causes of peat and sediment alternations. Supplementary material: Borehole thickness data and references are available at http://www.geolsoc.org.uk/SUP18788

Sedimentology and Coalbed Methane Geology of Middle Jurassic Coal Measures in Juhugeng Mine, Qinghai Province

Field-based lithofacies in the Middle Jurassic coal measures of the Juhugeng coal mine area of Qinghai Province have been identified employing lithology, geometry and lateral facies relationships. The coal measures were deposited in a range of environments spanning from braided river, delta to lake, and economic coal seams have been formed in the deltaic interdistributary bay and fluvial flood basin environments. The coal has a rank ranging from gas coal to coking coal, and the vitrinite macerals have a relatively high content, being from 60%~80%. Cleats and fractures of coal reservoirs are well developed. The isothermal adsorption experiments reveal that coal in the Juhugeng mine has relatively low Langmuir volume and relatively high Langmuir pressure with low to medium absorbability. All these conditions are beneficial to the formation and preservation of the coalbed methane.

Tomographic reconstruction of the exceptionally preserved trigonotarbid arachnid Eophrynus prestvicii

An exceptionally preserved specimen of the extinct trigonotarbid arachnid Eophrynus prestvicii (Arachnida: Trigonotarbida) from the Late Carboniferous (Duckmantian) British Middle Coal Measures of the UK is redescribed with the help of X-ray micro-tomography (XMT). Previous work is summarised and the correct spelling of the species name confirmed. Reconstruction of the void left by the original specimen within a siderite (ironstone) nodule reveals its three-dimensional structure as well as novel details which are difficult to resolve using traditional methods of study. The pedipalps and legs can now be reconstructed almost in their entirety and we can confirm that the chelicerae hung beneath the prosoma with a backwards-directed fang. Opisthosomal segmentation is clarified: a narrow tergite 1 is followed by eight further tergites (2–9), clearly demarked by their ornamentation. In general, a much more accurate picture of the spines and tuberculation ornamenting the dorsal surface of the body was resolved. ...

Arthropod types from Sparth Bottoms in the Howard Collection (Rochdale Museum Service)

Rochdale Museum Service holds a large collection of fossils from the important Carboniferous site of Sparth Bottoms (Lancashire, UK; Middle Coal Measures). Several of these are type specimens donated by Harold Howard in 1939. These objects were stored in the museum basement for several decades, and were thought to have been lost. The types are the holotype of the scorpion Eobuthus holtiPocock, 1911 and the holotype of the crustacean Anthrapalaemon grossarti var. holtiWoodward, 1911a. These species were not named after Howard, because the describers thought that Fred Holt was the rightful collector. The holotype of the myriapod Euphoberia woodwardiBaldwin, 1911 (put into synonymy with Palaeosoma robustumBaldwin, 1911) is known to have originally been in the collection, but was not located in a recent survey.

Morphology and systematics of anthracomartidae (Arachnida: Trigonotarbida)

Abstract: X‐ray microtomography (XMT) was applied to three species of the extinct arachnid order Trigonotarbida, hosted in siderite nodules from the late Carboniferous British Middle Coal Measures. All three, Cryptomartus hindi (Pocock, 1911), Cleptomartus plautus (Petrunkevitch, 1949) and Maiocercus celticus (Pocock, 1902), belong to the family Anthracomartidae. As well as providing interactive three‐dimensional visualisations of their likely appearance in life, XMT study has resolved new morphological detail, yielding key data about the likely stance and habitus of these early arachnids. Similarities in the form of the carapace, eyes and coxosternal region between anthracomartids and the Devonian genus PalaeocharinusHirst, 1923 are highlighted. Analogies in limb disposition are drawn between anthracomartids and modern crab spiders (Araneae: Thomisidae), which exhibit sit‐and‐wait style predatory behaviour. Anthracomartids are relatively common fossils at many Coal Measures localities. Although they appear to exhibit limited morphological variation, numerous genera and species have been proposed in the literature, often distinguished from each other on rather trivial characters. From our reconstruction of well‐preserved examples, we have resolved a number of common features likely to be present in a typical anthracomartid. Comparisons to this model suggest that the characters on which many anthracomartid genera are distinguished may be artefacts of preservation. We hence treat PromygaleFrič, 1901, BrachylycosaFrič, 1904, PerneriaFrič, 1904, CoryphomartusPetrunkevitch, 1945, CryptomartusPetrunkevitch, 1945, PleomartusPetrunkevitch, 1945, CleptomartusPetrunkevitch, 1949 and OomartusPetrunkevitch, 1953 as junior synonyms of the type genus of the family, AnthracomartusKarsch, 1882. Only the genera BrachypygeWoodward, 1878 and MaiocercusPocock, 1911 are additionally retained. Within Anthracomartus, Cleptomartus planusPetrunkevitch, 1949, Cryptomartus meyeriGuthörl, 1964, Cleptomartus hangardiGuthörl, 1965 and Cryptomartus rebskeiBrauckmann, 1984 are treated as junior synonyms of A. hindiPocock, 1911 (all syn. nov.). Cleptomartus plautusPetrunkevitch, 1949 and Anthracomartus denuitiPruvost, 1922 are treated as junior synonyms of A. priestiPocock, 1911 (both syn. nov.).

Provenance of Coals Recovered from the Wreck of HMAV Bounty

Coal samples from HMAV Bounty were analysed using standard techniques to shed light on their provenance. Petrographic analysis indicated they were Carboniferous, with high vitrinite and liptinite content and a mean random reflectance of vitrinite of 0.99%. Palynological analysis indicated the samples were derived from the Middle Coal Measures, Westphalian B. Combining coal rank (vitrinite reflectance), age, knowledge of seam distributions and coalfield history indicates the most like source to be the Durham Coalfield, possibly the Hutton or Low Main Seams. These coals were mined along the valley of the Weir in the latter part of the 18th century. © 2007 The Authors

The affinities of the Carboniferous whip spider Graeophonus anglicus Pocock, 1911 (Arachnida: Amblypygi)

ABSTRACTThe Late Carboniferous whip spiderGraeophonus anglicusPocock, 1911 (Arachnida: Amblypygi), is redescribed on the basis of the holotype and nine other specimens all preserved in sideritic nodules from the British Middle Coal Measures of Coseley, Staffordshire, UK. This species is clearly basal with respect to most living whip spiders, expressing numerous plesiomorphic character states and can be referred to both the suborder Paleoamblypygi and the ‘living fossil’ family Paracharontidae (with one Recent species), the latter based on an explict character of dorsal spination on the pedipalp femur. This suggests that crown-group Amblypygi originated by at least the mid-Palaeozoic.

A redescription of the Carboniferous arachnid Plesiosiro madeleyi Pocock, 1911 (Arachnida: Haptopoda)

AbstractPlesiosiro madeleyi Pocock, 1911, the monotypic representative of the fossil order Haptopoda Pocock, 1911 from the British Middle Coal Measures (Upper Carboniferous, Westphalian B) of Coseley, Staffordshire, is redescribed. A specimen from Sparth Bottoms, Lancashire is not a Plesiosiro and is referred to Arthropoda incertae sedis. Plesiosiro was probably a predator, having tooth-like projections on the femora for prey capture, and shows adaptations of the limbs for crawling in narrow spaces. The uncertain nature of the chelicerae, eyes and respiratory organs makes resolving the phylogenetic position of Plesiosiro difficult, though Haptopoda deserves its status as a separate order. Plesiosiro resembles both cythophthalmid and trogulid opilionids. Its broad prosoma–opisthosoma junction could be interpreted as a synapomorphy for Plesiosiro + Opiliones, but this character is not unique to these orders. Alternatively, Plesiosiro has a large, ventral opisthosomal sclerite. This is interpreted here as a genital operculum, a synapomorphy for Tetrapulmonata, and Plesiosiro is tentatively referred to this clade. Based on the synapomorphies of a divided sternum and subdivided telotarsi a relationship of the form: (Plesiosiro (Amblypygi (Thelyphonida + Schizomida))) is proposed.

The Midge Hall Valley Sewer: a case history in tunnelling through Coal Measures rocks

Abstract Engineering geology plays an indispensable part in the planning and construction of tunnels. This is demonstrated by the construction of the Midge Hall Valley Sewer tunnel through Middle Coal Measures rocks in the vicinity of Rochdale, Greater Manchester. A three-phased site investigation was carried out, at the planning, design and construction phases of the project. These lead to the determination of ground reference conditions, the choice of tunnelling method and the target cost of the tender. Throughout the project good communication was maintained between the client, the engineer to the project and both the site investigation contractor and the tunnelling contractor. This invoked confidence in the prediction of ground conditions forward of the tunnel face, and in the excavation and support methods used during the works. This example demonstrates the high value of good quality engineering geological input throughout a high risk construction project such as tunnelling.

Seismic facies analysis of Westphalian sequences of the southern North Sea

Differing seismic facies are observed from within the Westphalian sequences of the southern North Sea. A review of published synthetic seismograms and seismic data from known coal-bearing basins establishes seismic facies types and their relationships. Similar reflection character is recognized from Westphalian sequences in the southern North Sea and lithologies confirmed by borehole information. Probable sand/silt or clastic-prone Upper Coal Measures (Westphalian C/D) stages and coal-prone Lower and Middle Coal Measures (Westphalian A, B and part C) stages can be defined and mapped, providing information on the regional distribution of source and reservoir rocks and stratigraphic plays. It is suggested that sand-prone channel complexes or clastic dominated areas within the mainly A/B stages can be recognized and mapped, providing information on migration pathways and stratigraphic plays.

A mountain front model for the Variscan deformation of the South Wales coalfield

Access to the considerable geological database of British Coal, together with seismic evidence of subsurface relationships, has enabled the development of a structural model for the South Wales coalfield. Detailed site investigations are used as key examples. The simple broad synclinal nature of the coalfield masks a more complex structural system. Thrusting of Variscan age is largely confined to the Lower and Middle Coal Measures and throughout the central and northern coalfield is dominantly a forethrust system. However, along the south-crop a major backthrust system is developed which in places penetrates the Upper Coal Measures. The south-crop shows features analogous with a mountain front and is interpreted as a triangle zone, in which pre-existing basement faults have facilitated uplift. The lack of thrusting within the Upper Coal Measures, in contrast to the underlying Lower and Middle Coal Measures, suggests they have acted as a passive roof to the thrust system. Geographical variation in the intensity of the deformation can be related to the proximity of, and buttressing against, the Caledonian massif. Although broadly analogous with current models of foreland basin development and deformation, the South Wales coalfield demonstrates the importance of pre-existing massifs and lineaments in determining the precise evolution of an area.

Controls on alluvial architecture by synsedimentary faults in the Coal Measures of South Wales

AbstractA series of small‐scale gravity induced synsedimentary faults are described from the Middle Coal Measures (Westphalian B) of the South Wales Coalfield. The synsedimentary nature of the faults is indicated by abrupt changes in sediment thickness across faults, eroded fault scarps and the restriction of faulting to 8·75 m of sediment bounded by laterally persistent black shales above and a seatearth below. Evidence for the non‐tectonic origin of the faults is given by the presence of passive footwalls.Channel sandstone bodies occurring within the hanging walls of individual faults were deposited by discrete overbank flood events. Drainage patterns during flood events were controlled by topographic lows adjacent to the faults such that palaeocurrent data within the channel sandstone bodies indicate a S/SW transport direction parallel to fault strike.Synsedimentary fault movements resulted in the diagonal stacking of successively younger sandstone bodies adjacent to the faults, and an increase in tilt of the bodies with depth from 0 → 26°. The architecture of channel sandstone bodies was controlled by (1) the amount of fault movement and (2) fault block dimensions (or fault spacing). The interaction of these controlling factors resulted in deposition of symmetrical channel sandstone bodies over narrow fault blocks (12 m wide) with large fault displacements (7 m), asymmetrical sandstone bodies over wide fault blocks (30 m) with large fault displacement (7.5 m), and limited channel sandstone body development over fault blocks with small fault displacements (1.5 m).Synsedimentary faulting is thought to have been initiated by either seismic shock and/or overpressuring of pore fluids within buried mudstones.

Influence of a sandstone washout on the properties of an underlying coal seam

Properties of coals, either washed products or seam samples, from the Ryhope Five Quarter seam (Middle Coal Measures, Westphalian B) at Vane Tempest colliery, County Durham, UK, show significant differences over restricted areas of seam workings. The differences can be shown to be systematically related to roof lithology: where the properties of the coal indicate lower rank, the seam is overlain by a washout sandstone, whereas a mudstone/shale roof covers the higher-rank parts of the worked seam. No single unequivocal reason can be proposed to explain the lithological influence upon the coal properties, although differing thermal conductivities and rock permeabilities may play their part, but equally possible is early oxidation of the coal or differing degrees of degradation of the organic biomass at the time of deposition under either sands or muds. The importance of precise mapping of sand bodies overlying coal seams is stressed because of the deleterious effect that a sand body can have on the coking potential of a coal seam.

The concealed Upper Palaeozoic rocks of Berkshire and South Oxfordshire

Lithological, sedimentological and biostratigraphical (mainly palynological) details are presented of Devonian and Carboniferous rocks proved in five boreholes in Berkshire. The Devonian rocks include both fluvial Old Red Sandstone and marine facies. Two boreholes proved Dinantian rocks, of Courceyan (Lower Limestone Shales) age in one and probable Holkerian limestones in the other. These are overlain unconformably by Westphalian A and B strata (Lower and Middle Coal Measures), with are locally dominated by basic volcanics and intrusives. The Upper Coal Measures (late Westphalian C to early Westphalian D), chiefly composed of coarse-grained and conglomeratic sub-greywacke and belonging to the Arenaceous Coal Formation, unconformably overlie and overlap the earlier Carboniferous strata. The Upper Palaeozoic rocks were deformed into broad open folds during the latter part of the Variscan Orogeny, but steep dips in the south suggest proximity to the Variscan Front. The intermittent periods of erosion through Upper Palaeozoic time, and the late Carboniferous sedimentary history, can probably be related to deformational events in the Variscan Fold-Belt to the south.

The origin of anomalous fold patterns in the N.W. part of the South Wales Coalfield

Tectonic structures exposed in the Middle Coal Measures on the Glyn Glâs Opencast Coal Site are described. These are upright mesofolds with a NE-SW trend; meso and minor recumbent folds; and upright meso and minor N-S folds. All are buckle folds formed at a high structural level. The absence of such structures in the underlying and overlying strata is attributed to the greater competence of these beds. Although they form a deformation pattern similar to that of repeated folding in many fold belts, polyphase deformation is not regarded as being the cause of the structures. After comparison with structures elsewhere in the South Wales Coalfield they are regarded as being the result of main phase Variscan deformation in incompetent strata, the associated anomalous structures being due to localised accommodation in relation to penecontemporaneous sinistral tear faults.

Controls on mineral authigenesis in Coal Measures sandstones of the East Midlands, UK

AbstractAuthigenic clay mineral formation in fluvial sandstones and one brackish sandstone from the lower and middle Coal Measures of the East Midlands has been studied using XRD, optical microscopy and a variety of electron optical techniques. The sandstones are quartz-rich with minor feldspar and mica. The clay minerals present are kaolinite, chlorite and illite; they form 10–15% by volume of most of the sandstones. Both detrital and authigenic illite and chlorite are present but the kaolinite is entirely authigenic. Kaolinite and illite authi-genesis has been important in all the sandstones but authigenic chlorite is only abundant in the phyllosilicate-rich Silkstone sandstone. The controlling factors in the diagenesis of the sandstones were primary composition, environment of deposition, bed thickness, pore-fluid migration and composition, pressure and temperature. These interacting factors have been of varying importance in time and space in the diagenesis of the sandstones. Authigenic clay morphology appears to have been controlled by time and environment of formation, pore-fluid chemistry and, possibly, parent minerals.