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Depositional models for black shale formation rely on a detailed understanding of redox conditions and how they relate to basin development. Here, we calibrate multiple redox proxies (Fe speciation, U and Mo systematics, and pyrite framboid distributions) in the Bowland Shale, a major hydrocarbon unit in the Mississippian basin of northern England, and develop a depositional model for black shale deposition in basins adjacent to extensive carbonate platforms. The transition from deep ramp carbonates to basinal mudrocks initially occurred under oxic conditions before anoxic conditions began to expand from basin-center locations. By the end of Bowland Shale deposition, ~10 m.y. later, black shale deposition extended from the basin, where platform-edge carbonates were deposited, into shallow-water settings. By this stage, euxinic conditions were widespread throughout the Bowland Shale. The prolonged persistence of euxinia during younger Bowland Shale deposition, and the sharp transition to fully oxygenated facies at the basin margin, suggest there was a welldeveloped water-column pycnocline. Black shale development in silled basins is traditionally interpreted to form beneath a halocline with a positive water balance caused by freshwater run-off (estuarine circulation). This model is not considered appropriate in this case. Bowland Shale deposition was terminated by the onset of turbidite deposition supplied by a major deltaic system; but for most of its history, the basin was surrounded by carbonate platforms that are unlikely to have experienced brackish conditions. The encroachment of the clastic system saw the rapid improvement of basinal oxygenation in the uppermost Bowland Shale, and even minor turbidite sandstones within the black shales coincided with a weakening in the intensity of euxinia, which suggests that fresher, sediment-laden waters flushed out and oxygenated the basin. We therefore suggest a warm saline bottom-water model for black shale deposition, with basinal waters generated on the adjacent carbonate platforms due to evaporation. Such a scenario is likely more broadly applicable to basinal black shales that developed adjacent to shallow-water carbonate successions. [ABSTRACT FROM AUTHOR]

The empirical interpretation of cone penetration test (CPT) cone factors (Nk) can be subject to considerable variability for clays derived from weathered mudstones, leading to significant deviations in the estimation of undrained shear strength (Su). This paper presents a comparison of triaxial and CPT data from a site investigation in clays derived from weathered mudstones in central England. Corrected cone factors (Nkt,UU) were derived from a one-to-one comparison of 94 pairs of unconsolidated, undrained triaxial and CPT data from equivalent depths. The performance of the cone factors was evaluated using a training set (75 pairs) and a test set (19 pairs). A parametric study was used to explore the variability of Nkt,UU, quantified using the coefficient of variation (COVNkt,UU), for varied separation distance thresholds (Ds) between individual triaxial and CPT data. The absolute deviation between the laboratory shear strength (Su(Lab)) and that predicted from CPT profiles (Su(CPT)) was not sensitive to Nkt,UU values in the range 25 < Nkt,UU < 31. The parametric study showed that Ds could be increased from 50 to 250 m, to include more data pairs for estimates of Nkt,UU, without substantially increasing COVNkt,UU. [ABSTRACT FROM AUTHOR]

The Mercia Mudstone Group (MMG) crops out extensively across England and Wales and its thermal properties are required for the design of infrastructure such as ground source heating and cooling schemes and electrical cable conduits. Data from the literature and new data from a borehole core have been compiled to generate an updated range of thermal conductivities related to rock type and the lithostratigraphy. These indicate a total range in saturated vertical thermal conductivity of 1.67–3.24 W m−1 K−1, comprising 1.67–2.81 W m−1 K−1 for mudstones, 2.12–2.41 W m−1 K−1 for siltstones and 2.3–3.24 W m−1 K−1 for sandstones. These data are all from measurements on samples and there will be uncertainty when considering the thermal properties of the rock mass owing to micro- and macrostructural features. Geometric mean modelling of thermal conductivity based on mineralogy has overestimated the thermal conductivity. Correction factors for the modelled thermal conductivities have been calculated to allow a first estimate of MMG thermal conductivities when only mineralogical data are available. Measured thermal diffusivities from the borehole core were in the range of 0.63–3.07 × 10−6 m2 s−1 and are the first measured thermal diffusivities to be reported for the MMG. [ABSTRACT FROM AUTHOR]

Abstract: Analyses of organic-rich mudstones from wells that penetrated the Upper Jurassic Kimmeridge Clay Formation, offshore United Kingdom, were performed to evaluate the nature of both organic and inorganic rock constituents and their relation to porosity in this world-class source rock. The formation is at varying levels of thermal maturity, ranging from immature in the shallowest core samples to mature in the deepest core samples. The intent of this study was to evaluate porosity as a function of both organic macerals and thermal maturity. At least four distinct types of organic macerals were observed in petrographic and SEM analyses and they all were present across the study area. The macerals include, in decreasing abundance: 1) bituminite admixed with clays; 2) elongate lamellar masses (alginite or bituminite) with small quartz, feldspar, and clay entrained within it; 3) terrestrial (vitrinite, fusinite, semifusinite) grains; and 4) Tasmanites microfossils. Although pores in all maceral types were observed on ion-milled surfaces of all samples, the pores (largely nanopores with some micropores) vary as a function of maceral type. Importantly, pores in the macerals do not vary systematically as a function of thermal maturity, insofar as organic pores are of similar size and shape in both the immature and mature Kimmeridge rocks. If any organic pores developed during the generation of hydrocarbons, they were apparently not preserved, possibly because of the highly ductile nature of much of the rock constituents of Kimmeridge mudstones (clays and organic material). Inorganic pores (largely micropores with some nanopores) have been observed in all Kimmeridge mudstones. These pores, particularly interparticle (i.e., between clay platelets), and intraparticle (i.e., in framboidal pyrite, in partially dissolved detrital K-feldspar, and in both detrital and authigenic dolomite) are noteworthy because they compose much of the observable porosity in the shales in both immature and mature samples. The absence of a systematic increase in organic porosity as a function of either maceral type or thermal maturity indicates that such porosity was probably unrelated to hydrocarbon generation. Instead, much of the porosity within mudstones of the Kimmeridge appears to be largely intraparticle and interparticle (adjacent to inorganic constituents), so the petroleum storage potential in these organic-rich mudstones largely resides in inorganic pores. [Copyright &y& Elsevier]

Abstract: A total of 25 mudstone samples from two sections in northwest Germany and northeast England (palaeolatitude ~40°N), respectively, of Hauterivian and early Barremian age were analysed using TEX86 palaeothermometry. In addition, the stable isotope ratio (δ18O, δ13C) and trace element content (Mg, Sr, Fe, and Mn) of 138 belemnite guards from the same two outcrops were determined to reconstruct past sea water temperatures. The TEX86 based sea surface temperatures were constantly warm (24–26°C) throughout the entire Hauterivian for both sections and even warmer for the early Barremian (27–30°C). Stable water temperatures prevailed over a period of ~6.4Ma in the southernmost part of the Boreal Realm. These findings clearly support the view of warm equable conditions for the Hauterivian at least for mid latitudinal settings. A constant off-set between higher TEX86-derived temperatures and lower δ18OBel-derived temperatures was observed. This may be explained by either increased sea water salinities, a deep dwelling habitat of belemnites or a combination of both. A by 3‰ higher salinity of the sea water below the thermocline, which would at least partly explain the by ~2‰ too positive δ18OBel values, cannot be ruled out in these epicontinental settings. A habitat of the belemnites below the thermocline in perhaps 50–100m water depth may have contributed to the positive δ18OBel data as well. The temperature difference between the TEX86 and the δ18OBel findings might therefore reflect a vertical temperature gradient of the water column of 4–5°C and a salinity of the subsurface waters of 38‰. [Copyright &y& Elsevier]

The article presents a study on the geology of rock properties of the Cretaceous mudstones in the Clair oil field which was affected by wellbore instability in Shetlands, England. It says that cretaceous mudstones are characterized by minor anisotropy and low strength. It analyzes the impact of mud invasion through a multistage triaxial test at high pressure in drilling mud using commercial software to assess borehole instability of rock that fails on weak planes.

Abstract: Emplacement of the Variscan S-type Cornubian Batholith initiated the formation of the historical World-class Sn and Cu deposits and extensive tourmalinisation of southwest England. The hypothesis is tested that the Sn and tourmaline mineralisation were wholly formed by magmatically-derived hydrothermal fluids, with no requirement for a contribution from the stripping of country rocks by circulating hydrothermal fluids. From simple geochemical modelling, sufficient Sn concentrations to match those in the main (>90% of granite outcrop) biotite granites (average of 23mg/kg) and to produce the large Sn deposits can be derived by partial melting of pre-granite southwest England crust at geologically realistic levels of partial melting (30%), fractionation (10 to 50%) and % melt-aqueous fluid partitioning (assumed to be 6wt.% of the mass of the granite batholith). In contrast, insufficient B (<600mg/kg) can be modelled for the melt to reach saturation with respect to tourmaline (>>700mg/kg), or B concentrations found in many of the granites. We conclude that tourmaline in the biotite granites was formed from magmatically-derived hydrothermal fluids which emanated as a result of first and possibly second boiling. An additional source of B for the hydrothermal fluids may have been the devolatilisation of stoped blocks of country rock mudstones. These findings provide fundamental constraints on the evolution of the Cornubian batholith which is used as a model for a large number of Sn provinces worldwide. [Copyright &y& Elsevier]

Abstract: The sediment packages analyzed for benthic foraminifera consist of mudstones with interbedded sandstones deposited in shallow delta-influenced shelf to deltaic environments. The sections are located in Spitsbergen, the Barents Sea, northern North Sea and Yorkshire, and range in age from Late Triassic to Middle Jurassic. Salient features of the foraminiferal successions are: (1) The assemblages consist entirely or dominantly of agglutinated taxa. (2) The faunal diversities are extremely low. (3) The dominant genera are Ammodiscus and Trochammina. (4) The species are generally of small size compared to usual dimensions within the genera. The features listed above suggest that the assemblages were adapted to restricted conditions (clearly divergent from those of a normal marine shelf), where the main limiting factors were low salinity and reduced amount of dissolved oxygen in unstable, storm-influenced environments. Evidence for environmental conditions is obtained from modern analogues, although the large evolutionary changes in foraminifera during post-Jurassic time make it difficult to find such analogues. Additional information is derived from functional morphology, sedimentary features and paleogeography. The analyzed sediment packages show close faunal similarities suggesting opening of a marine pathway, which connected the paleo-Arctic Ocean with the western European shelf seas in Early Jurassic. A depositional biofacies model of the small-sized Ammodiscus–Trochammina assemblages envisages a delta-influenced shelf environment, where high freshwater influx would have created a density-stratified water column with a tendency to develop hypoxic conditions in its deeper parts. The depth interval between fair-weather and storm wave base (the offshore-transition zone) is indicated as the habitat of the small-sized Ammodiscus–Trochammina assemblages. In this zone, benthic biota would have been stressed by intermittent periods with moderate hypoxia combined with lowered salinity and storm impacts. [Copyright &y& Elsevier]

The late Wenlock Series (Homerian Stage) of the northern Midland Platform (central England) comprises silty mudstones and limestones of the upper part of the Coalbrookdale and overlying Much Wenlock Limestone formations. Based on outcrop studies and borehole data, the sequence stratigraphical interpretation developed for the inliers of the West Midlands is slightly revised, and extended to the stratotype sections along Wenlock Edge. A single third-order cycle of sea-level change is identified, punctuated by a regressive-transgressive episode associated with a higher-order glacioeustatic cycle, allowing the upper Wenlock Series of the area to be divided into two subsequences (A and B). Subsequence A and the early transgressive systems tract began with regression associated with the basal sequence boundary in late Cyrtograptus lundgreni Biozone times. This was followed by a period of slow transgression or still stand, allowing shallower water carbonate environments to prograde. A minor phase of regression followed, resulting in the generation of the shallowest water deposits of both the Lower Quarried Limestone and Farley members (of the MuchWenlock Limestone and Coalbrookdale formations, respectively). The overlying Subsequence B and the late transgressive systems tract are marked by transgression and a period of rapid sea-level fluctuation and are likely contained within the Gothograptus nassa Biozone. A minor highstand is widely recognizable at this time. The rest of Subsequence B consists of an initial phase of weak progradation (highstand systems tract), followed by a marked regression (falling stage systems tract) culminating in an erosive upper sequence boundary at or close to the top of the Monograptus ludensis Biozone, but within the uppermost Much Wenlock Limestone Formation. Above Subsequence B is a marked transgression into the Lower Elton Formation and the Ludlow Series. Both late Wenlock lowstands and the succeeding flooding events have been recognized on other palaeocontinents, reflecting the eustatic nature of sea-level changes reported here. [ABSTRACT FROM AUTHOR]

A series of boreholes in Horton Quarry, northwest Yorkshire (Horton-in-Ribblesdale Inlier) penetrated mudstones and slates belonging to the Austwick Formation (Windermere Supergroup) overlying laminated mudstones of the Ingleton Group. Illite (IC) and chlorite (ChC) crystallinity measurements indicate a metamorphic inversion between the two groups of mudrocks. The Windermere Supergroup mudrocks are mostly in the high anchizone or epizone, whereas the Ingletonian samples are lower grade in terms of IC, and are mostly deep diagenetic zone or low anchizone. Hence younger strata at higher grades rest on older strata at lower grades, creating a metamorphic inversion. Ingletonian slates exposed at Pecca Falls on the River Twiss show epizonal and anchizonal IC values, and greywacke samples from Ingleton Quarry contain pumpellyite. This suggests that grade in the Ingletonian may increase to the NW from the Horton to Ingleton inliers. K-white mica b cell dimensions show further differences between the Ingleton Group and the Windermere Supergroup. The Ingletonian samples are characterized by low b cell values (8.989-9.035, mean 9.007 Å), whereas the Windermere Supergroup has higher values in the range 9.022-9.034, mean 9.027 Å. The Windermere Supergroup values are similar to those recorded from the Windermere Supergroup of the southern Lake District, and Lower Palaeozoic rocks from the Scottish Southern Uplands, and are consistent with metamorphism in a low heat flow, convergent geotectonic setting. The Ingletonian b cell values suggest metamorphism in a higher heat flow setting, most likely an extensional basin. The metamorphic inversion at Horton and differences in K-white mica b cell dimensions suggest that the Ingleton Group and Windermere Supergroup strata evolved in different geotectonic settings and record two separate metamorphic events. The discovery of the metamorphic inversion at Horton provides further evidence in favour of an Ordovician rather than Neoproterozoic depositional age for the controversial Ingleton Group. [ABSTRACT FROM AUTHOR]

Abstract: A complete Triassic succession is exposed in the cliffs of the Devon coast in south-west England, UK where it forms part of the Dorset & East Devon World Heritage Site. The upper part of the succession, the Middle to Late Triassic Mercia Mudstone Group, consists of c. 450 m of predominantly red mudstones and associated evaporites that were deposited in playa lakes in hot deserts. The Group has an extensive onshore and offshore outcrop and subcrop in the U.K. where it locally comprises over 3000 m of red beds with thick halites. The Devon coast section is the type for the Group and is the most complete exposure of the Keuper Marl facies in north-west Europe. In its middle part, the Dunscombe Mudstone Formation comprises a 25 to 40 m-thick laterally variable succession of green, purple and grey laminated mudstones with thin interbeds of calcareous siltstone/sandstone, and thicker beds of autobreccia related to gypsum/anhydrite and halite dissolution. It represents a fluvio–lacustrine and probably cooler climatic interval that is thought to have lasted, on the basis of palaeontological and magnetostratigraphic evidence, for most of the Carnian Stage (c. 12 Ma). Elsewhere in Europe the Carnian Stage is represented by fluvial deposits including the Esterienschichten and Schilfsandstein Formations in Germany. At the type section on the Devon coast the Dunscombe Mudstone includes a lenticular unit of bioturbated, predominantly fine-grained sandstone up to 4 m thick, the Lincombe Member, that has not been recorded in inland sections in the county. When traced northwards into Somerset, thin lenticular sandstones, the North Curry and Sutton Mallet Sandstone Members, are locally present at similar stratigraphical levels in the lower part of the Dunscombe Mudstone. A detailed analysis of the sedimentology of the three principal occurrences of these arenaceous units revealed 13 lithofacies and 6 ichnofabrics that suggest deposition in similar fluvio–lacustrine settings. Their palaeoenvironmental interpretation and correlation is more complex than previously thought. The Lincombe Member is interpreted as a geographically isolated sedimentary body that was deposited in a shallow, oxygenated freshwater lake. In Devon it passes upwards and laterally into lake-margin and lake delta-plain deposits. The North Curry Sandstone was deposited in a series of broad, shallow channels that crossed a low-relief topography. Laterally, along strike, the channel sands either pass into or terminate against more argillaceous lacustrine deposits. In contrast, the depositional environment of the Sutton Mallet Sandstone is interpreted as relatively small-scale channels with low flows and possible channel switching. Fluvio–lacustrine intervals are relatively common within playa-lake successions, but there are few published accounts of ancient examples that are sufficiently detailed to allow the complex interactions of these ephemeral shallow-water environments to be understood. The sedimentological and ichnological descriptions and analyses of the Triassic example presented here will be applicable to other fluvio–lacustrine sediments deposited in dryland environments. [Copyright &y& Elsevier]

Abstract: Minor bedforms within the mudstone-dominated Early Jurassic Hettangian Saltford Shale Member (Liasicus up to Angulata Chronozone) of the Blue Lias Formation in central England, indicate weak seafloor erosion in a mid to outer ramp setting. Distal storm flows below maximum storm wave base are proposed as the most likely generative mechanism for silty scour and gutter casts that enclose concentrations of well-preserved schlotheimiid ammonites and arthropod trace fossils. Within the upper part of the Saltford Shale (probably Angulata Chronozone), a discrete layer of reworked and bioencrusted limestone nodules signifies an episode of more persistent seafloor erosion. The immediately overlying strata, transitional to the Hettangian–Sinemurian Rugby Limestone Member, are relatively bioturbated and feature fossils of macrobenthos, as well as shell concentrations resembling relatively proximal storm beds. This suggests that the reworked nodule horizon marks sea-level fall, rather than stratigraphic condensation associated with sediment starvation. The biostratigraphic evidence raises the possibility that this erosional episode correlates with a mid-Angulata Chronozone hiatus documented from the Wessex Basin, southwest England. Equally however, it could be linked to contemporaneous movement on one or more nearby faults, affecting the southern part of the English East Midlands Shelf. [Copyright &y& Elsevier]

Gypsum veins and faults were studied in red mudstones of the Upper Triassic Mercia Mudstone Group, in the Bristol Channel Basin, exposed in E-W-trending cliffs at Watchet on the Somerset Coast (SW England). In nodular gypsum horizons, individual gypsum nodules are connected by subhorizontal gypsum veins. In evaporite-free mudstone layers, however, dense anastomosing networks of gypsum veins occur. In a 300 m long profile dissected by 28 (mostly) normal faults with small displacements, 24 faults have veins following them, indicating palaeofluid transport along the fault planes. Ninety-seven cross-cutting relationships and mostly perpendicular vein fibres indicate that the veins are primarily extension fractures. The thickest veins in the vein network are subhorizontal (160 measurements), indicating a vertical orientation of the minimum principal compressive stress (horizontal basin compression). Such a stress state may have existed during basin inversion associated with Alpine compression (late Cretaceous to early Tertiary). I propose that the gypsum veins are the result of hydrofracturing. In the gypsum nodules, then presumably consisting of anhydrite, overpressure was generated related to the hydration of anhydrite to gypsum. Stress concentration around the nodules led to rupturing and injection of thin subhorizontal hydrofractures. Some of the calcium-sulphate saturated fluids were then transported upwards along the faults and gained access to evaporite-free mudstone layers where dense anastomosing vein networks developed. Most veins were arrested during their propagation by layers with contrasting mechanical properties (stress barriers). Some veins, however, propagated through the barriers along faults to shallower levels. The dense networks of mineral veins observed in Watchet indicate that hydrofractures can generate a very high temporary permeability in fluid reservoirs. [ABSTRACT FROM AUTHOR]

The process of pyrite oxidation with the resulting formation of sulfates in disturbed pyrite-rich mudstone is recognised in the UK as a potential engineering hazard. This paper describes and quantifies the extent of pyrite oxidation in Lower Lias Clay in Gloucestershire using a large data set collected in 1998 and 1999 during the investigation of twenty-eight, approximately 30-year old highway structures affected by the thaumasite form of sulfate attack. Most of the structures have concrete spread footings founded on undisturbed and relatively unweathered Lower Lias Clay, and are surrounded by backfill of reworked Lower Lias Clay. Chemical, X-ray diffraction and X-ray fluorescence analyses are used to determine the composition of the soils. Differences are identified in the sulfides, sulfates and total sulfur concentrations between unweathered and weathered Lower Lias Clay and the backfill. The work is supported by pyrite oxidation trials in the laboratory on clay samples stored in bags and sealed tubes. The results indicate that pyrite oxidation, sulfate formation and leaching have occurred as the Lower Lias Clay weathers in situ and also during and following disturbance and reworking for highway construction. The amount and rate of pyrite oxidation are estimated, and comparison is made with the concentration of sulfate in the surrounding groundwater, and the extent of thaumasite sulfate attack measured at adjacent structures. [Copyright &y& Elsevier]

Septarian concretions occur at several horizons within the Oxford Clay Formation, a marine mudstone containing pristine aragonite and immature biomarker molecules. They record the passage of at least four generations of pore fluids, the first of marine origin and the last still present in cavities. Concretion bodies formed, cracked, and calcite and pyrite precipitated in and around the cracks within the sulphate reduction zone, as demonstrated by C, O, S and Sr isotopic composition (Pore fluid 1). Before major compaction, sandstone dykes were intruded locally, and baryte precipitated, followed by coarse calcite cements with isotopically light oxygen and radiogenic strontium, indicating the introduction of meteoric-derived water (Pore fluid 2). Later, coarse celestine within concretions has distinct sulphur-isotopic composition and requires a further, geographically restricted, water source (Pore fluid 3). Celestine-bearing concretions contain water in tight cavities whose isotopic composition is close to that of modern precipitation. Its chemistry shows that it is equilibrating with pre-existing minerals implying a relatively recent origin (Pore fluid 4). The mineralogy of the Oxford Clay concretions shows that complex results can follow from a simple burial and uplift history, and that multiple generations of pore fluids can pass through a low-permeability clay. [ABSTRACT FROM AUTHOR]

The Bowland Basin (nothern England) contains a series of carbonates and terrigenous mudstones deposited during the Ivorian to early Brigantian Two regional depositional environments are indicated by facies and facies associations. Wackestone/pactstone and calcarenite facies indicate deposition in a carbonate ramp environment, while lime mudstone/wackestone, calcarenite and limestone breccia/ canglomerate facies, often extensively slumped, represent a carbonate slope environment Stratigraphic relations suggest that the depositional environment evolved from a ramp into a slope through the Dinantian. Two main sediment sources are indicated by the sequence; an extra-basinal terrigenous mud source and carbonate from the margins of the basin. Deposition from suspension and from sediment a supply of gravity flows, in situ production and remobilization of sediment during sedimentary sliding were important processes operating within the basin. Periods of enhanced tectonic activity in the late Chadian to early Arundian and late Asbian to early Brigantian are indicated by basin-wide horizons of sedimentary slide and mass flow deposits. Both intervals were marked by a decline in carbonate production resulting from inundation and uplift/emergence. The first of these intervals separates deposition on a seafloor with gentle topography (carbonate ramp) from a situation where major lateral thickness and facies variations were present and deposition took place in a carbonate slope environment. The second interval marks the end of major carbonate deposition within the Bowland Basin and the onset of regional terrigenous sedimentation. [ABSTRACT FROM AUTHOR]

Widespread evaporitic sulphate horizons occur in the frequently dolomitic Mercia Mudstones (Upper Triassic) of the English Midlands. The mudstones were deposited on an extensive peneplain which had areas of upstanding minor relief (Charnwood Massif, Derbyshire—Pennines, London Platform). Horst and graben structures formed during the early and middle Triassic, controlled late Triassic sedimentation rates and peneplain slope directions. A stable isotope study (S,C,O) of the sulphates and dolomites of the Trent Formation indicates that during the deposition of the lower Fauld Member grabens such as the Needwood Basin in Staffordshire and areas marginal to a graben such as Newark m Nottinghamshire had a marine brine regime with minor continental input. Using constraints applied by sulphate concentrations of modern waters in arid environments, the ratio of volume of marine input to volume of continental input lay between 3:1 and 4:1. The horst area (East Leake, Nottinghamshire) was strongly influenced by continental brines which derived sulphate from the exposed Carboniferous Hathern Anhydrite Series. A predominantly continental brine regime existed across the whole area during deposition of the overlying Hawton Member. Periodic marine influxes gave rise to thin sulphate horizons whilst continental run-off was occasionally sufficient to form temporary lakes. The Blue Anchor Formation (Rhaetian) was deposited in a lacustrine environment with waters of mixed marine and continental origin. Salinities were lower than those of the preceding Trent Formation brines. [ABSTRACT FROM AUTHOR]

The meander-belt deposit comprises a sandstone resting on an erosion surface and bounded above and below by massive varicoloured mudstones with rootlet traces. The sandstone unit is composed of six bodies separated from one another, horizontally, by erosion surfaces; together the bodies form a single multilateral sand body. Internally each body is composed of lateral accretion units inclined at up to 6° from the horizontal. Vertical sequences of facies show significant variations but the grain size generally fines upwards. The principal lithofacies within the sandstones are, in common ascending order, intraformational conglomerate, large-scale cross-bedded, horizontal bedded and small-scale cross-laminated sandstone, and alternate sandstones and mudstones. Current directions are normal to the true slope of accretion surfaces and show insignificant scatter within individual bodies but are very diverse overall. Five of the said bodies are believed to represent individual point bars, and one body an abandoned channel. Together they comprise the meander belt. The river was subject to very variable discharges and carried high suspended loads. Analysis of vertical profiles indicates that grain size segregation along the length of the point bars caused, differentiation of the bars into coarse-grained heads and sandy tails. [ABSTRACT FROM AUTHOR]

Compares the lower Silurian mudstones of the Lake District in England with modern marine muds. Presence of unfossiliferous green mudstones; Evidence of a black pyritic lithology; Presence of striped mudstones with prominent carbonaceous and silt laminae.

Examines the ironstones in the Upper Oxfordian of southern England. Fauna dominating the chamosite oolite mudstones; Factors responsible for ironstone development.

In 1985 a watching brief during gravel extraction at Hemington Fields, Castle Donington, Leicestershire, revealed a substantial timber and stone structure buried beneath 2-2.5 m of alluvium. Salvage excavation and a further watching brief have enabled the structure to be identified as a twelfth century mill dam associated with a possible low breast mill. This is the only mill site of this date examined on a major river and has provided important information on medieval water management. Such sites indicate the great potential for archaeology within the floodplain of major rivers and contributes to a survey of palaeochannels in this area of the Trent valley. [ABSTRACT FROM AUTHOR]