Carboniferous Coal Measures Research Articles

A remarkable spiny arachnid from the Pennsylvanian Mazon Creek Lagerstätte, Illinois

Abstract A new genus and species of arachnid (Chelicerata: Arachnida), Douglassarachne acanthopoda n. gen. n. sp., is described from the late Carboniferous (Moscovian) Coal Measures of the Mazon Creek Lagerstätte, Illinois, USA. This is a unique animal with distinctive large spines on the legs. It has a subovate body, a segmented opisthosoma, and a terminal anal tubercle. The legs are robust and appear to have been similar in construction throughout the limb series, with heavy spination of the preserved proximal podomeres. The mouthparts and coxo-sternal region are equivocal. The preserved character combination does not permit easy referral to any known arachnid order, living or extinct, thus the new fossil in placed as Arachnida/Pantetrapulmonata incertae sedis. It contributes to an emerging pattern of disparate body plans among late Carboniferous arachnids, ranging from anatomically modern members of living orders through to extinct taxa, such as the present fossil, whose phylogenetic position remains unresolved. UUID: http://zoobank.org/b70f5f95-9c8b-4389-bee5-b6031bff2ee2

Gravity imaging of sub-Zechstein geological structures in the UK sector of the North Sea using the gravity layer stripping method

Extensive geophysical databases, covering the UK sector of the North Sea, have been used to gravity layer strip the sedimentary layers down to the base Zechstein so that the gravity response of the Carboniferous and deeper strata can be identified and structurally interpreted. To achieve this, the average bulk density grids for each layer were derived using Gardner's functions derived from well velocity and density logs. The resulting residual gravity response of each layer and the Moho response were then removed from the Free air gravity anomaly to generate the isostatic gravity response of the crust below the base Zechstein. This gravity response was used to re-evaluate the British Geological Survey interpretation over the Mid North Sea High (MNSH) and was able to identify the same crustal structures. Using the tilt derivative method, a positive gravity anomaly was found to parallel the central fracture zone that forms a northern extension of the Dowsing fault zone. This anomaly can be traced north across the MNSH with offsets coinciding with the WSW–ENE basement lineaments. To the south, the southern North Sea basin is well defined by the stratigraphic layer depth and thickness maps as well as the residual gravity maps which identify the structures associated with the low-density Carboniferous Coal Measures.

A fish for Phoebe: a new actinopterygian from the Upper Carboniferous Coal Measures of Saddleworth, Greater Manchester, UK, and a revision of Kansasiella eatoni

Abstract The origin of crown Actinopterygii has been dated to near the Devonian-Carboniferous boundary, but poor phylogenetic signal occludes the origin of modern actinopterygian biodiversity. Scarcity of comparative endoskeletal anatomy from this period likely contributes to the uncertainty. For example, only a handful of neurocrania have been described from the Carboniferous period despite an abundance of fossil taxa. Here we present a new actinopterygian, Phoebeannaia mossae gen. et sp. nov., from the Bashkirian Coal Measures of Saddleworth, Greater Manchester, UK, represented by an exceptionally preserved neurocranium and associated dermal bones. Morphological similarities to the Virgilian Kansasiella eatoni prompted comparative study and construction of a new neurocranial character matrix. Subsequent systematic analysis enabled identification of a cluster of similar Late Palaeozoic neurocrania, exploration of trends in braincase evolution across time, and investigation of potential causes of cladistic instability. Our neurocranial dataset reliably places this new specimen on the neopterygian stem near Kansasiella, but it struggles to incorporate extant taxa such as Polypteriformes, leading to uncertainty in branching pattern and inferred neurocranial transformation series. This work triples the number of complete Carboniferous neurocrania described with modern microcomputed tomography and provides a framework for future testing of large-scale hypotheses regarding the diversification and origin of ray-finned fishes.

Constraining the Geochemical Fingerprints of Gases from the UK Carboniferous Coal Measures at the Glasgow Geoenergy Observatories Field Site, Scotland

Usage of thermal energy contained in abandoned, flooded, coal mines has the potential to contribute to low carbon heating or cooling supply and assist in meeting net-zero carbon emission targets. However, hazardous ground gases, such as CH4 and CO2, can be found naturally in superficial deposits, coal bearing strata and abandoned mines. Determining the presence, magnitude, and origin of subsurface gases, and how their geochemical fingerprints evolve within the shallow subsurface is vital to developing an understanding of how to manage the risk posed by ground gases in geoenergy technology development. Here, we present the first CH4 and CO2 concentration-depth profiles and stable isotope (δ13CCH4, δ13CCO2, and δDCH4) profiles obtained from UK mine workings, through analysis of headspace gas samples degassed from cores and chippings collected during construction of the Glasgow Observatory. These are used to investigate the variability of gas fingerprints with depth within unmined Carboniferous coal measures and Glasgow coal mine workings. Stable isotope compositions of CH4 (δ13CCH4 = −73.4‰ to −14.3‰; δ13CCO2 = −29‰ to −6.1‰; δDCH4 = −277‰ to −88‰) provide evidence of a biogenic source, with carbonate reduction being the primary pathway of CH4 production. Gas samples collected at depths of 63–79 m exhibit enrichments in 13CCH4 and 2H, indicating the oxidative consumption of CH4. This correlates with their proximity to the Glasgow Ell mine workings, which will have increased exposure to O2 from the atmosphere as a result of mining activities. CO2 gas is more abundant than CH4 throughout the succession in all three boreholes, exhibiting high δ13CCO2 values relative to the CH4 present. Gases from unmined bedrock exhibit the highest δ13CCO2 values, with samples from near-surface superficial deposits having the lowest δ13CCO2 values. δ13CCO2 values become progressively lower at shallower depths (above 90 m), which can be explained by the increasing influence of shallow groundwaters containing a mixture of dissolved marine carbonate minerals (∼0‰) and soil gas CO2 (−26‰) as depth decreases. Our findings provide an insight into the variability of mine derived gases within 200 m of the surface, providing an important ‘time-zero’ record of the site, which is required in the design of monitoring approaches.

Coaly and lacustrine hydrocarbon source rocks in Permo-Carboniferous graben deposits (Weiach well, Northern Switzerland)

Permo-Carboniferous graben sediments in the North Alpine Foreland Basin (NAFB) include Upper Carboniferous (Stephanian) coal-measures and lower Permian (lower Autunian) lacustrine shales with high organic matter contents. Coals are probably the source for a gas accumulation in Switzerland, while the bituminous shales are potential source rocks for oil. In order to study the hydrocarbon potential of coal and bituminous shales and to contribute to the understanding of their depositional environment, 90 core samples from the Weiach-1 well (northern Switzerland) were investigated using organic petrographic, palynofacies, Rock-Eval pyrolysis, and geochemical techniques (incl. biomarker analysis and compound-specific carbon isotopy). Carboniferous coal seams are up to 10 m thick and were deposited in low-lying freshwater mires. They contain a significant gas potential and reached a maturity stage related to the onset of gas generation. Sapropelic rocks were not observed in the coal-bearing succession. Organic matter-rich Permian shales (Autunian shales) were deposited in anoxic lakes with a stratified water column. The organic matter is of mixed aquatic and terrigenous origin. δ13C values of chlorophyll-derived isoprenoids provide evidence for reworking of organic matter in the water column. The Autunian shales have a strongly varying, but locally very good oil potential. They reached early oil window maturity, but did not yet generate significant amounts of hydrocarbons. The main shale interval in the studied borehole is about 12 m thick and will generate about 0.35 tHC/m2 when mature. A comparison with literature data shows that it is possible to distinguish oils generated from Permian, Jurassic and Oligocene source rocks based on biomarker ratios and isotope data.

Geochemical characteristics, origin and carbon isotope reversal of the presalt natural gas in the Lower Paleozoic Ordovician carbonates, Ordos Basin, China

The origin and potential source of the presalt natural gas in the Lower Paleozoic Ordovician carbonates within the Ordos Basin, China, is heavily debated, and the causes of carbon isotope reversal are currently unclear. This study analyzes the source and origin of the presalt natural gas and determines the reasons for carbon isotope reversal. The results show that the nonhydrocarbons contain CO2, H2S, and N2 and some gas samples have high H2S contents of 9.02%–23.58%. The dryness coefficient (C1/C1+) of 91.06%–99.99% (ave. 98.34%) suggests that the presalt gas is mainly a dry gas with some wet gas and that it originates from a high-to over-mature source. However, the results show that the presalt natural gas is primarily a wet-gas-cracking gas, rather than a kerogen-cracking gas, with a certain amount of coal-type gas mixing and it mainly originated from oil-prone marine carbonate source rocks rather than the Permian–Carboniferous coal measures. The gas has different types of carbon isotope reversal patterns, and the δ13C2 values become negative at Roequ > 1.5%. The mixing between the oil-cracking and wet-gas-cracking gas at Roequ > 1.5% results in carbon isotope reversal (δ13C1 > δ13C2), rather than Rayleigh and migration fractionation. The occurrence of thermochemical sulfate reduction (TSR) is supported by the high abundance of H2S in the presalt gas, reservoir bitumen in dissolved pores, secondary calcite with negative δ13Ccarbonate of −21.1‰ to −9.7‰, and diagenetic cubic pyrite. It is evident that the heavy δ13C2 values (greater than −28‰) and the carbon isotope reversal of δ13C2 > δ13C3 of the presalt natural gas at Roequ < 1.5% are related to TSR. This study also establishes a new model of the carbon isotope reversal of the natural gas, which is primarily controlled by its thermal maturity and TSR. Six carbon isotope patterns can be well explained and are supported by real gas samples from the presalt strata, and two types of carbon isotope reversal are predicted.

A geochemical and mineralogical update on two major tonsteins in the UK Carboniferous Coal Measures

Samples of two prominent tonsteins in the UK Carboniferous coal-bearing strata, representing kaolinised mafic ash and felsic ash have been comprehensively analysed by ICP-MS, laser ablation ICP-MS, SEM/EDX, XRD and XRF. Compositions have been compared with possible parent ashes in order to establish the extent to which elements are lost or retained during the alteration process. This is more readily achieved for the mafic tonsteins because they can be directly linked to the local, contemporaneous volcanics. The volcanic source of the felsic tonsteins is not known with certainty and the geochemical comparisons are made with modern volcanics from what is thought to be a similar tectonic/magmatic setting. Evidence of element migration during the tonstein formation has also been obtained by analysing the adjacent coals. Some mobility of U, Th, Nb, Y, Zr Hf and Ta is demonstrated, which imposes some constraints on the use of discrimination diagrams for the interpretation of original ash composition and tectonic setting. Notwithstanding some mobility of the incompatible elements, the discrimination diagrams are of use in providing broad igneous groupings. The TiO2/Al2O3 ratio is useful in that these two elements show the least mobility and the ratio is diagnostic of ash composition and sediment inclusion in the ash if the quartz content is also taken into account. The sediments associated with the felsic tonstein do not have a constant value for this ratio, which increases with grain size and quartz content and enables ash with included sediment to be recognized. Based on SEM/EDX and LA ICP-MS element locations have been identified. Zircon is a diagnostic volcanogenic mineral which makes an important contribution to the trace element budget, but there are other sources, notably a range of phosphate minerals, some of igneous origin and others diagenetic. This is also demonstrated from the whole rock geochemistry which shows there is an excess of U and Th over that which can be accommodated within the calculated zircon content.The REE profiles for the two types of tonstein differ significantly to each other. One is comparable with the profiles recorded from the associated basalts and partial melting of the upper mantle is thought to be responsible. The felsic tonstein, on the other hand, shows a profile common to many rhyolites with evidence of significant fractional crystallization. Again, in spite of some mobility during the alteration, the REE profiles appear to reflect the original ash composition, which is consistent with other aspects of the geochemistry.

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.

Geological evolution of the Central Pontides

Abstract Before the Late Cretaceous opening of the Black Sea, the Central Pontides constituted part of the southern margin of Laurasia. Two features that distinguish the Central Pontides from the neighbouring Pontide regions are the presence of an extensive Lower Cretaceous submarine turbidite fan (the Çağlayan Formation) in the north, and a huge area of Jurassic–Cretaceous subduction–accretion complexes in the south. The Central Pontides comprise two terranes, the Istanbul Zone in the west and the Sakarya Zone in the east, which were amalgamated before the Late Jurassic (Kimmeridgian), most probably during the Triassic. The basement in the western Central Pontides (the Istanbul Zone) is made up of a Palaeozoic sedimentary sequence, which ends with Carboniferous coal measures and Permo-Triassic red beds. In the eastern Central Pontides, the basement consists of Permo-Carboniferous granites and an Upper Triassic forearc sequence of siliciclastic turbidites with tectonic slivers of pre-Jurassic ophiolite (the Küre Complex). The Küre Complex is intruded by Middle Jurassic granites and porphyries, which constitute the western termination of a major magmatic arc. Upper Jurassic–Lower Cretaceous shallow-marine limestones (the İnaltı Formation) lie unconformably over both the Istanbul and Sakarya sequences in the Central Pontides. Two new measured stratigraphic sections from the İnaltı Formation constrain the age of the İnaltı Formation as Kimmeridgian–Berriasian. After a period of uplift and erosion during the Valanginian and Hauterivian, the İnaltı Formation is unconformably overlain by an over 2 km-thick sequence of Barremian–Aptian turbidites. Palaeocurrent measurements and detrital zircons indicate that the major part of the turbidites was derived from the East European Platform, implying that the Black Sea was not open before the Aptian. The Çağlayan turbidites pass northwards to a coeval carbonate–clastic shelf exposed along the present Black Sea coast. In the southern part of the Central Pontides, the Lower Cretaceous turbidites were deformed and metamorphosed in the Albian. Albian times also witnessed accretion of Tethyan oceanic crustal and mantle sequences to the southern margin of Laurasia, represented by Albian eclogites and blueschists in the Central Pontides. A new depositional cycle started in the Late Cretaceous with Coniacian–Santonian red pelagic limestones, which lie unconformably over the older units. The limestones pass up into thick sequences of Santonian–Campanian arc volcanic rocks. The volcanism ceased in the middle Campanian, and the interval between late Campanian and middle Eocene is represented by a thick sequence of siliciclastic and calciclastic turbidites in the northern part of the Central Pontides. Coeval sequences in the south are shallow marine and are separated by unconformities. The marine deposition in the Central Pontides ended in the Middle Eocene as a consequence of collision of the Pontides with the Kırşehir Massif.

Genetic types and origins of natural gases from eastern Fukang Sub-depression of the Junggar Basin, NW China: Implication for low-mature coal-derived gases

Although the Fukang Sub-depression is the largest hydrocarbon generation depression in the Junggar Basin and promises favorable potential for oil and gas exploration, only several small–medium oil/gas accumulations have been discovered so far. After analyzing the molecular and stable carbon isotopic compositions of natural gases and its associated low molecular weight hydrocarbons (LMWHs) from eastern Fukang Sub-depression, their genetic types and origins are discussed in this study. Natural gases are wet gases with an average dryness coefficient of 0.84. Stable carbon isotopes of methane and ethane are well correlated with the thermal evolution trend of coal-derived gases. The C5–7 LMWHs are enriched in methyl cyclohexane but they lack n-alkanes, indicating a predominance of higher plant input. Gases have maturities ranging 0.76%–0.93%Ro and are well consistent with their low n-heptane (H) and iso-heptane (I) contents. The geochemical characteristics of natural gases from eastern Fukang Sub-depression are quite similar with those from the Turpan–Hami Basin. Their gases are considered to be low-mature gases derived from the Lower–Middle Jurassic coal measures. In contrast, they show remarkable differences with those from the Wucaiwan gas field; they are considered to have high-mature gases derived from the Carboniferous coal measures.

Unravelling the relative contributions of climate change and ground disturbance to subsurface temperature perturbations: Case studies from Tyneside, UK

When assessing subsurface urban heat islands (UHIs) it is important to distinguish between localized effects of land-use change and the impacts of global climate change. However, few investigations have successfully unraveled the two influences. We have investigated borehole temperature records from the urban centres of Gateshead and Newcastle upon Tyne in northeast England, to ascertain the effects on subsurface temperatures of climate change and changes in ground conditions due to historic coal mining and more recent urban development. The latter effects are shown to be substantial, albeit with significant variations on a very local scale. Significant subsurface UHIs are indeed evident in both urban centres, estimated as 2.0°C in Newcastle and 4.5°C in Gateshead, the former value being comparable to the 1.9°C atmospheric UHI previously measured for the Tyneside conurbation as a whole. We interpret these substantial subsurface UHIs as a consequence of the region’s long history of urban and industrial development and associated surface energy use, possibly supplemented in Gateshead by the thermal effect of trains braking in an adjacent shallow railway tunnel. We also show that a large proportion of the expected conductive heat flux from the Earth’s interior beneath both Gateshead and Newcastle becomes entrained by groundwater flow and transported elsewhere, through former mineworkings in which the rocks have become ‘permeabilised’ during the region’s long history of coal mining. Discharge of groundwater at a nearby minewater pumping station, Kibblesworth, has a heat flux that we estimate as ∼7.5MW; it thus ‘captures’ the equivalent of roughly two thirds of the geothermal heat flux through a >100km2 surrounding region. Modelling of the associated groundwater flow regime provides first-order estimates of the hydraulic transport properties of ‘permeabilised’ Carboniferous Coal Measures rocks, comprising permeability ∼3×10−11m2 or ∼30 darcies, hydraulic conductivity ∼2×10−4ms−1, and transmissivity ∼2×10−3m2s−1 or ∼200m2day−1; these are very high values, comparable to what one might expect for karstified Carboniferous limestone. Furthermore, the large-magnitude subsurface UHIs create significant downward components of conductive heat flow in the shallow subsurface, which are supplemented by downward heat transport by groundwater movement towards the flow network through the former mineworkings. The warm water in these workings has thus been heated, in part, by heat drawn from the shallow subsurface, as well as by heat flowing from the Earth’s interior. Similar conductive heat flow and groundwater flow responses are expected in other urban former coalfield regions of Britain; knowledge of the processes involved may facilitate their use as heat stores and may also contribute to UHI mitigation.

Sustainability of thermal energy production at the flooded mine workings of the former Caphouse Colliery, Yorkshire, United Kingdom

Abandoned, flooded, coal mine workings are an artefact of fossil fuel exploitation that can be repurposed as a renewable energy resource. The warm subsurface waters that fill former workings can be developed to provide efficient and low-carbon heat generation using ground source heat pumps. In order to determine the long-term suitability of flooded mine workings as a sustainable thermal resource we have to understand the hydrological components of the system and how they interact in response to exploitation-related disturbance. We investigate pump induced mixing dynamics at the former Caphouse Colliery, which has been pumped since 1996 for regional water level management but only recently started to be explored as a thermal resource. Initial findings from the first 6months of study show virtually no variation in physiochemical, major ion or stable isotope values. However, placed in context with archived values from 2004 to the present, we see a general pattern of mine water quality recovery punctuated by a doubling of Cl− values (150mg/l to >300mg/l) which may suggest recent ingress of deeper-sourced saline waters. This is supported by O and H isotopic values, which are indicative of ancient, perhaps Late Pleistocene, confined waters. Sulphur isotope values (19.7–23.8‰) are abnormally high as compared to typical values for Carboniferous Coal Measures (0–10‰). There is no simple explanation, so further data collection and investigation are required, though we note that these values are similar to Lower Carboniferous seawater values. The relative stability of recent parameters suggests that Caphouse waters represent a dependable thermal resource. However, much about the hydrogeology of the Caphouse system is still uncertain, so further work is required to check the persistence of recent trends.

Carboniferous araneomorph spiders reinterpreted as long-bodied harvestmen

Archaeometa nephilina Pocock, 1911 from the Late Carboniferous (Bashkirian/Moscovian: Duckmantian, c.315 Ma) Coal Measures of Coseley in the English West Midlands was originally interpreted as an araneomorph spider (Arachnida: Araneae). It is, in fact, a harvestman (Arachnida: Opiliones), albeit one with an unusual, long-bodied morphology. Another Coseley fossil, Arachnometa tuberculata Petrunkevitch, 1949, was also interpreted as an araneomorph spider, but it is not well preserved, and is regarded as Opiliones incertae sedis. Interestingly, the Archaeometa Pocock, 1911 body plan, here also revealed through computed microtomography (µCT), has morphological parallels with some modern laniatorid harvestmen in the family Assammidae. However, the Coal Measures fossils do not preserve unequivocal laniatorid apomorphies, and so are referred to an uncertain position within Phalangida (transferred herein from Araneae). The Archaeometa specimens are further examples of Carboniferous Opiliones, which were originally misidentified, and contribute to a picture of an increasingly diverse Coal Measures harvestman fauna.http://zoobank.org/urn:lsid:zoobank.org:pub:E7951158-75F3-46AF-87FB-AE10AD50D94E

Potential for Aerobic Methane Oxidation in Carboniferous Coal Measures

Carbon (C), geologically sequestered in coal, is gradually released to the atmosphere as CH4 and CO2. Recent anthropogenic activity (coal mining) has rapidly increased the rate of C reallocation from coal deposits into the atmosphere, which has deleterious effect on the climate as both gases are effective infrared absorbers. In the current study we demonstrate that the coal bearing sedimentary rocks possess potential of biological methane oxidation. Viable methanotrophic bacteria, capable of methane oxidation at ambient air and a range of methane concentrations were found in coalbearing formations of the Upper Silesian (USCB) and Lublin Coal Basins (LCB). Factors controlling activity of the aerobic methanotrophic bacteria in the deep subsurface such as, depth, methane concentration, available electron acceptors, moisture and nutrients availability were investigated along with paleoenvironmental factors (temperature changes during and after burial and paleohydrological infiltration). The distribution and activity of the methanotrophic bacteria in the deep subsurface were found to be influenced by geological conditions among which evolution of paleotemperatures and paleohydrological conditions play a predominant role. The data presented along with analysis of molecular composition of the coalbed gases in various coal basins worldwide has led to the conclusion that aerobic methanotrophy may be a widespread process, which, to our knowledge, so far has not been included in investigations concerning C cycling in the subsurface.

The Ellismuir fossil arachnid – the only known Scottish Carboniferous trigonotarbid

Synopsis Elaverimartus pococki Petrunkevitch 1953 from above the Kiltongue Coal Seam (Langsettian) of Ellismuir, Baillieston (Glasgow) is the only example of the extinct arachnid order Trigonotarbida recorded from the Carboniferous Coal Measures of Scotland. The fossil is from the Robert Dunlop collection and, although not so well preserved, historical documentation in the National Museums Scotland includes a preliminary drawing of the specimen prepared by Ben Peach, together with an unpublished manuscript name, ‘ Palaeophalangium Scoticum ’, implying an ancient Scottish harvestman (Arachnida, Opiliones). A mention in a published meetings report of the Transactions of the Geological Society of Glasgow unfortunately made this manuscript name available. Its status as a widely overlooked nomen nudum is clarified here for completeness. A proposal to treat Elaverimartus Petrunkevitch 1953 as a junior synonym of Aphantomartus Pocock 1911 would render E. pococki a junior homonym of an already synonymized species. Given the inadequate preservation of the holotype, we prefer to treat E. pococki as a nomen dubium and thus circumvent the need to replace the name.

Buried trees and basin tectonics: A discussion

Rooted tree trunks up to 12m tall, buried in growth position, are a feature of Euramerican late Carboniferous Coal Measures. They provide evidence of episodes in which generation of accommodation space, and resultant sediment accumulation, occurred at rates far in excess of the net long-term (cm/kyr) rates for the sections in which they occur; and they do so in a variety of tectonic settings. Episodic, metre-scale, co-seismic subsidence is the likeliest explanation for this phenomenon. Such episodic subsidence is unlikely to be a unique tectonic attribute of Carboniferous Coal Measure basins. Instead, it seems that the trees’ morphology and ecology uniquely favoured their preservation as casts in growth position, thus providing a yardstick for the scale and rapidity of the co-seismic subsidence and accumulation. Other epicontinental shallow marine/paralic basins lack this means of gauging of the rate of subsidence, but it is possible that most of them also experienced episodic subsidence events. Such events would explain the capture of records of, for example, high-energy beach deposition and tidal sedimentation. They also suggest the need for a reappraisal of the significance of metre-scale parasequences in both siliciclastic and carbonate rocks.

Euthycarcinoids

The euthycarcinoids are a mysterious group of extinct, possibly amphibious, arthropods. Like many groups of arthropods their affinities remain enigmatic. They comprise 15 species known mainly from the Late Carboniferous Coal Measures of Europe and North America, although they have been found in older rocks in Argentina and Australia. The oldest known euthycarcinoid is Apankura machu, from the Late Cambrian of Argentina, and the youngest is Euthycarcinus kessleri, from the Middle Triassic of France.

Horsetails get the wind up

Horsetails get the wind up

The engineering geology of the Nottingham area, UK

Abstract Nottingham was built near a crossing point on the River Trent in the East Midlands of England. Initially, the city developed on a low sandstone hill close to the north bank of the river, which provided a secure, well-drained location above the marshes that bordered the river. Geologically, Nottingham stands at the boundary between Palaeozoic rocks to the north and west, and Mesozoic and Cenozoic strata to the south and east. The area is underlain by coal-bearing Carboniferous Coal Measures, Permian dolomitic limestones, Permo-Triassic mudstones and weak sandstones, Jurassic clays and Quaternary glacial and alluvial deposits. Artificial deposits, resulting from the social, industrial and mineral extraction activities of the past, cover the natural deposits over much of the area. This geological environment has underpinned the economic development of the area through the mining of coal (now largely ceased), oil extraction that was important during World War II, brickmaking from clays, alluvial sand and gravel extraction from the Trent Valley, and gypsum extraction from the Permo-Triassic mudstones. The Permo-Triassic sandstone is a nationally important aquifer, and has also been exploited at the surface and from shallow mines for sand. However, this history of the use and exploitation of mineral deposits has created a number of environmental problems, including rising groundwater levels, abandoned mine shafts and mining subsidence, and, within the city itself, the occasional collapse of artificial cavities in the sandstone and contaminated land left by industrial activities. Natural constraints on development include gypsum dissolution, landslides, rockfalls, swell–shrink problems in Jurassic clays and flooding. Occasional minor earthquakes are attributed to movements related to coal mining or natural, deep geological structures. Thus, Nottingham's geological context remains an important consideration when planning its future regeneration and development.

Early Devonian putative gyracanthid acanthodians from eastern CanadaInternational Geoscience Programme (IGCP) Contribution 491, Middle Palaeozoic Vertebrate Biogeography, Palaeogeography, and Climate.

In 1890, Traquair assigned isolated fin spines from the Early Devonian of eastern Canada to a new gyracanthid acanthodian Gyracanthus incurvus , based on the similarity of the distinctive oblique ridges on the spines to the ornament on the large robust fin spines of Gyracanthus spp. from the British Carboniferous Coal Measures. Other similarly ornamented spines from the Early Devonian of Germany were tentatively assigned in 1933 by Gross to the same genus as a new species Gyracanthus? convexus . Based on examination of the type material, as well as newly collected specimens from Emsian sandstones and mudstones of the Gaspé Peninsula, Quebec and the Atholville beds, New Brunswick, we erect a new genus Ankylacanthus gen. nov. for these two species. Spines of the new genus are distinguished by being laterally flattened and thin-walled, with a single row of denticles along one side of the posterior groove, and having thin spine ridges ornamented with low smooth nodes. Other Early to Middle Devonian specimens in South America, Saudi Arabia, and Iran are also tentatively referred to the new genus, which seems to have had an early (Lochkovian–Pragian) cross-north Gondwanan distribution, transferring into Laurentia and spanning Emsian–Eifelian times.