Derbyshire Dome Research Articles

The first oil exploration campaign in the UK, 1918–22

Abstract The story of UK onshore exploration goes back to the days of World War I and was prompted by the increasing use of oil for the war effort. The war was drawing to a close as the campaign commenced in 1918. The UK government sponsored the drilling with a budget of £1 000 000 and the work was undertaken by S. Pearson & Sons, a UK engineering company owned by Lord Cowdray (Weetman Pearson). Pearson also had oil interests and he owned the Mexican Eagle Company that had had exploration success in Mexico. Pearson hired a team of American geologists to select suitable drilling locations in the UK. The Carboniferous rocks in the area surrounding the Derbyshire Dome in England and the Midland Valley in Scotland were chosen because of their similarity to the oil-producing areas of Pennsylvania and West Virginia in the USA. Eleven wells were sunk: seven in Derbyshire, two in North Staffordshire and two in Scotland. The first well to be spudded was at Hardstoft in Derbyshire in October 1918 and it was also the first oil discovery. The geological reasoning behind the selection of the drilling sites will be compared with the actual results from 1918–22.

Late Visean and Early Namurian trilobites from the northern and eastern margins of the Derbyshire Dome

SUMMARY Strata of late Visean (P 1c and P 2 ) and early Namurian (E l and E 2 ) age that crop out on the northern and eastern flanks of the Derbyshire Dome have yielded trilobites from several horizons in the Monsal Dale Limestones Formation (dark lithofacies), the Eyam Limestones Formation, the Longstone Mudstone Formation and the lower part of the Edale Shale Group. Certain levels are crowded with disarticulated exoskeletal parts, accompanied by some articulated specimens. Paladin is the most widespread genus in these formations, both geographically and stratigraphically, with Cummingella, Baliothyreus gen. nov. and Eocyphinium having more limited distributions. The dark lithofacies at the top of the Monsal Dale Limestones Formation is established as the type lithology for Paladin bakewellensis Osmólska, Eocyphinium seminiferum (Phillips) and for Martin’s ‘ Entomolithus Onicites ( Derbiensis )’, now referred to Paladin. In this paper, Paladin derbiensis (Phillips), P. bakewellensis Osmólska, P. eakringensis Osmólska, Baliothyreus becki gen. et sp. nov. and B. fissisolanum gen. et sp. nov. are described. The Paladin species contrast with those present in coeval strata in the Askrigg Block and farther north, in north and south Wales, and in the Bristol district; they appear to be restricted to Derbyshire and the adjacent East Midlands. Baliothyreus has not been found outside Derbyshire.

The Snelston Ridge: evidence for a concealed ridge of mineralized Dinantian rocks to the south of the Derbyshire Dome

SUMMARY Little is known of the southern continuation of the Lower Carboniferous (Dinantian) rocks of the Derbyshire Dome where they lie concealed beneath Triassic rocks at the margin of the Needwood Basin. Evidence from regional Bouguer gravity anomaly surveys pointed to the existence of a ridge of shallow Dinantian rocks, here called the Snelston Ridge, largely concealed by Triassic strata apart from two small inliers. The NNW–SSE trending ridge was proved by a borehole which intersected (Dinantian) Widmerpool Formation rocks at a depth of 61 m. Evidence from a seismic reflection profile indicates that the ridge, at least at Birchwoodpark (Snelston), is probably an asymmetrical, fault-controlled anticline. There is, however, no evidence for any significant changes in the thickness of Dinantian rocks hereabouts. The base metal potential of the Snelston Ridge was investigated using detailed geophysical and geochemical surveys and drilling. A borehole on the top of the mineralized mudmound that forms the Limestone Hill Inlier proved minor replacement galena–sphalerite–baryte mineralization with up to 10% Pb over an intersection of about 11 m. Two boreholes on the flanks of the feature revealed little sign of mineralization, indicating that it is restricted to the exposed dolomitized summit of the mudmound.

A seismic refraction study of the upper crustal structure of the Derbyshire Dome

SUMMARY Results from four seismic refraction profiles crossing the Derbyshire Dome are described and interpreted in terms of their sub-Dinantian limestone structure. The apparently simple surface outcrop of the dome belies a more complex basement structure which is divided into a northern and southern province by the NW-SE trending Cronkston-Bonsall Fault Zone. To the north of the fault zone a Lower Palaeozoic refractor is identified beneath the Carboniferous rocks with a velocity of 5.53 km/s, which is tentatively correlated with Ordovician volcanics in the Woo Dale borehole. However, to the south the C4ronkston-Bonsall Fault Zone, a Charnian (Precambrian) basement is inferred, with a velocity of 5.7 km/s, which is downthrown to the north across the faults. This fault zone may represent the local surface expression of the north-eastern margin of the Midlands Microcraton.

Fluid Inclusion Studies on the Ecton Hill Copper Deposits, North Staffordshire

AbstractThermometric and D-ICP analysis of fluid inclusions in calcite and fluorite show that the fluids responsible for extensive carbonate-hosted copper mineralization in the Ecton Hill area were low-temperature (< 100 °C), high-salinity (19.5 to 23 wt. % NaCl equivalents) brines strongly enriched in calcium (mean Ca:Na wt. ratio = 1.9). Compared with the fluids responsible for classical ‘Mississippi Valley type’ lead-zinc deposits elsewhere in the south Pennine orefield, the Ecton ore-fluids were of lower temperature and slightly more enriched in potassium. Despite these subtle differences, the data are consistent with a basinal brine model for ore genesis in this western part of the orefield similar to that envisaged for the remainder of the orefield. These Ca-Na-K-Cl, copper-bearing brines were most probably derived from the Cheshire basin located to the west of the Derbyshire Dome.

Dinantian sedimentation and the basement structure of the Derbyshire Dome

AbstractThe depositional history of the Dinantian on the Derbyshire Dome can be divided into three phases: (1) pre‐Holkerian: onlap of an irregular basement surface by evaporite and carbonate sediments, (2) Holkerian to Asbian: sedimentation on a carbonate shelf formed by the merging of early Dinantian depocentres following burial of the basement topography, and (3) Brigantian: formation of intrashelf basins and the development of a carbonate ramp on part of the pre‐existing shelf.A model of the basement structure underlying the Derbyshire Dome is presented to explain the location of the Brigantian intrashelf basins and carbonate ramp. The basement consists of two main tilted fault blocks separated by a smaller tilt block. Movement on faults bounding the tilt blocks caused the development of intrashelf basins. The basin margins were controlled by structures which developed in the cover sediments. The carbonate ramp present during the late Brigantian developed in response to an eastward tilting of the basement.

Seismic refraction evidence for a basement ridge between the Derbyshire Dome and the W of Charnwood Forest

Results from a 40-km seismic refraction profile crossing a series of positive gravity anomalies extending across the postulated mouth of the Widmerpool Gulf are reported. A refractor with a similar velocity to the Precambrian rocks of Charnwood Forest dips away from Charnwood to the southern flank of the Derbyshire Dome to a depth of 2 km. This refractor is faulted into horst and graben structures. The horst blocks correlate with the positive gravity anomalies. A northern boundary fault to the Precambrian outcrops of Charnwood is defined.

TEMPERATURE TIME-LAGS IN LIMESTONE GROUNDWATERS OF THE SOUTHERN PENNINES: A DISCUSSION

Pitty (1976) has reported time-lags between air temperatures and emergent groundwater temperatures in limestone areas of the central and southern Pennines. He proposed that such time-lags directly reflect the gross permeability of limestones with respect to groundwater movement and, on this basis, suggested radical differences in the hydrological characters of the limestone areas of Derbyshire and Yorkshire. The purpose of this note is to indicate the errors involved in attempting to extract quantitative hydrological information from observations of this kind. Groundwater temperatures were measured by the author at twenty-one localities in the south-eastern part of the Derbyshire Dome during 1976 and 1977. Measurements were made at least monthly and often fortnightly with an estimated precision of ± 0.1°C. Temperatures measured at most sites varied between 7°C and 10°C with standard deviations for within-site variations typically less than 1°C and often less than 0.5°C (based on thirty-one observations over eighteen months). A general pattern of water temperature variability seems to exist in the area; variances in recorded temperatures increase in order of: thermal springs < natural risings < perched springs < mine waters. This probably reflects a sequence of decreasing residence times in the aquifer. Time-lags were seen to exist between air temperatures and water temperatures at most sites visited. Temperature hydrographs for three sites (Fig. 1), a mine water, a natural rising and a perched spring, demonstrate lags of two or three months behind air temperatures. There appear to be no significant differences between time-lags at these sites although contrasting …

THE STRUCTURE OF THE CONCEALED PRE-CARBONIFEROUS BASEMENT OF THE DERBYSHIRE DOME FROM GRAVITY DATA

SUMMARY Bouguer anomalies over the Derbyshire Dome indicate a positive structural relief for the pre-Carboniferous basement, and their qualitative and quantitative interpretations show that the basement reaches its maximum elevation towards the southern edge of the dome. The Bouguer map contours in the central area suggest that the surface of the basement there may be at a greater depth than in both the northern and southern parts. It is also inferred from the gravity models that the basement is at a shallower depth to the west of the limestone outcrop than to the east and that its eastern margin has a comparatively steeper slope. Lateral extensions of the basement beyond the area of the dome are postulated, based on the existence of features with positive Bouguer anomalies.

A Recent Deep Borehole near Eyam, Derbyshire

THE oldest exposed rocks in the northern part of the Derbyshire Dome are limestones belonging to the Upper Seminula (S2) Zone of the Dinantian. Previously only one borehole has been considered to have passed through the entire Dinantian sequence of this area into the sub-Carboniferous floor, at Woo Dale, about 5 km east of Buxton1. Drilling commenced in S2 dolomites and continued in limestones and dolomites, all provisionally regarded as Visean in age, to 272 m. Below this a 2 m breccia separated the limestones from volcanic rocks, which were tentatively considered to be Precambrian and' continued to the total depth of 312 m.

The mineralogy and origin of interbedded clay wayboards in the Lower Carboniferous of the Derbyshire Dome

AbstractInterbedded clays, or clay wayboards, from the Lower Carboniferous Limestones of Derbyshire and Staffordshire, are discussed in terms of their geological relationships, textural features and mineralogy, and comparison is made between these clays and other interbedded argillaceous materials from the area. It is concluded that the clay wayboards are the argillation products of contemporaneous volcanic ashfalls, and lie within the definition of K‐bentonites.Stratigraphical and palaeogeographical aspects of clay wayboard distribution are briefly discussed, and it is shown that despite the probable widespread extent of individual clay horizons they are only of limited value for the purposes of correlation.

Edaphic and Vegetational Zoning on the Carboniferous Limestone of the Derbyshire Dales

Many interesting descriptions of the soils and vegetation types of the chalk downlands have been published, but there is little available information on the carboniferous limestones of north-western Britain. In these uplands, the hard nature of the parent rock and the damp, cool climate produce an environment markedly different from that of the wellknown chalk grasslands in the south and east. This is reflected in the nature of the vegetation, typical calcareous grassland being limited to the steep slopes and flushed valleys, while on the gentler slopes and high plateaux there is an acidic type of grassland or heath. The distribution of the various communities is closely correlated with an edaphic zonation. The development of the soil is determined, first by climate, and secondly by topography through its influence on soil accumulation and stability and on drainage conditions. Hence the sequence of soil and vegetation types can be described as a catena, using the term as defined by Morison, Hoyle and Hope-Simpson (1948), 'a grouping of soil vegetation types linked in their occurrence by conditions of topography and repeated in the same relationship to each other wherever the same conditions occur'. This concept has been applied in the following description of the plant communities and soils of the Derbyshire limestone where all stages in the transition from calcareous grassland to moorland and from rendzina to podsol can be found. The carboniferous limestone exposed in the southern Pennines, known as the Derbyshire Dome, is an undulating plateau dissected by steep-sided dales. The limestone is in the form of a massive bed, the upper layers of which are impregnated with nodules and bands of chert. This is a flint-like substance which is not readily weathered but is broken down by mechanical action and remains as scattered fragments in the soil. Between this chertified limestone and the pure white limestone under it, there are occasional beds of a doleritic intrusion, toadstone, which outcrops at the surface in several areas producing locally an acid type of soil bearing heath vegetation, not to be confused with heath of leached limestone areas. The climate can be described as submontane with high humidity and rather low temperature throughout the year. The annual rainfall is from 40 to 50 in., falling mainly in October, November and December, but the soil remains very wet throughout the winter and spring owing to the low rate of evaporation. In general, with increase in altitude the rainfall rises and temperature decreases, leading to an increase in the precipitation: evaporation ratio. There are also frequent snowfalls on high ground and strong * Now at the Nature Conservancy, 91 Victoria St., London.

Announcements

THE proceeds of the Daniel Pidgeon Fund for 1937 of the Geological Society of London have been awarded in equal proportions to Dr. G. F. Claringbull, who proposes to investigate the geology and petrology of the Ross of Mull granite, and Mr. F. W. Cope, who proposes to map the central region of the Derbyshire dome, and to correlate the Lower Carboniferous rocks of the area with those of North Wales, Westmorland, and the type section of the Avonian.

The Glacial Geology of the Derbyshire Dome and the Western Slopes of the Southern Pennines

I. I ntroduction . The region dealt with in this paper is roughly triangular in shape, extending from its northern apex at Blackstone Edge, east of Littleborough, to beyond Crich in the south-east, and along the southern line of the Pennines to Madeley and Market Drayton in the south-west. It comprises the Carboniferous Limestone plateau of the Derbyshire Dome, the ‘Edges’ of the grits, and the intervening valleys of the shales of the Millstone Grit of the south-western slopes of the Pennines, together with the marginal plains of Triassic rocks which border these in East Lancashire, Cheshire, Staffordshire, and Derbyshire. Some idea of the nature of the relief of the country may be gleaned from the accompanying map (Pl. XIX), and of the solid geology from the quarter-inch maps of the Geological Survey of England &amp; Wales (Sheets 7 &amp; 11). This area forms the southerly continuation of that described by one of us in an earlier communication to this Society. A brief outline of some of the main conclusions set out below was presented at the Manchester Meeting of the British Association in 1915. Numerous notes on the Glacial geology of this area, dealing chiefly with the distribution and character of the drifts and the erratics, are to be found scattered throughout English Glacial literature. Reference will be made to the most important of these, in the course of this paper, as occasion arises. The Glacial deposits, with their smooth and striated boulders which thickly cover the plains, the far-travelled erratics

Societies and Academies

LONDON. Geological Society, Jan. 23.—J. K. Charlesworth: The South Wales end-moraine. The Irish Sea ice stood over Cardigan Bay at the period of the maximum advance of the Newer Drift period, and ponded back the natural drainage of northern Pembrokeshire and southern Cardiganshire to form a chain of extra-glacial lakes connected by marginal streams. The end-moraine of the Newer Drift passes across eastern and southern Wales. In northern Pembrokeshire and southern Cardiganshire it was laid down along the edge of the Irish Sea ice. Farther east, the moraine is practically continuous, and represents the marginal product of the local Welsh ice, which was centred in the mountains of Central Wales, the Carmarthenshire Vans, the Brecon Beacons, the Black Mountains, and the mountains of Radnor Forest. This ice flowed beyond the outlets of the great valleys of the east to form the valley-glaciers of the Severn and other rivers, and extended southwards on to the coastal plain of Glamorgan. The Newer Drift is of early Magdalenian age.—A. Jowett and J. K. Charlesworth: The glacial geology of the Derbyshire dome and the western slopes of the Southern Pennines. The Derbyshire Dome of the Southern Pennines was overridden at the period of maximum glaciation by ice from the north and north-west. This is shown by the occurrence of patches of true boulder clay, by the wide distribution of erratics of Lake District and Galloway rocks over the dome and along its valleys, and other evidence. The upper limit of the erratics from the north follows the outer flanks of the southwestern Pennines at about 1250 feet above sea-level. The ice-recession from this position was associated with a copious marginal drainage, which eroded a well-developed suite of channels linking a number of big extra-glacial lakes in the valleys of the western Pennines.