Northumbria Rocks
Total Page：16
File Type：pdf, Size：1020Kb
Open University Geological Society Journal Symposium Edition 2003 Northumbria Rocks University of Durham Contents Setting the scene: the geological framework and history of Northumbria 1 Paul F V Williams, Staff Tutor in Earth Science, The Open University in the North The Yoredale Cycles of Northumbria: High-Frequency Clastic-Carbonate Sequences 5 of the Mid-Carboniferous Icehouse World Maurice Tucker1, James Gallagher1, Kirstin Lemon1 & Melanie Leng2 1Department of Earth Sciences, University of Durham 2NIGL, British Geological Survey, Nottingham, The Caledonian Orogeny in northern Britain – a state of the arc 11 Howard A Armstrong, Department of Earth Sciences, University of Durham. Alan W Owen, Division of Earth Sciences, University of Glasgow. The Hydrogeology of the Great Northern Coalfield 19 Paul Younger, School of Civil Engineering & Geosciences, University of Newcastle Fissuring in the Magnesian Limestone of County Durham 25 Brian Young, BGS District Geologist – Northern England, British Geological Survey, Edinburgh The Fossil Collections at the Hancock Museum, Newcastle upon Tyne 27 Steve McLean, Hancock Museum, Barras Bridge, Newcastle upon Tyne Early Palaeozoic magmatism in northern England 34 David Millward, British Geological Survey, Edinburgh The Story of the Weardale Granite 39 Martin Bott, Emeritus Professor of Geophysics, University of Durham Northumberland Rocks - a story that has to be told 44 Stuart Monro, Scientific Director, Our Dynamic Earth, Edinburgh -------------------------------- A Taste of Namibia 45 Chris Crivelli Seven unconformaties and a thrust fault: north west Highlands excursion 4-11 May 2002 51 Margaret Donnelly, Lynn Everson, Stuart Fairley, Margaret Kennedy, complied by Jane Hickman Book reviews 18, 26, 33,58 It is the responsibility of authors to obtain the necessary permission to reproduce any copyright material they wish to use in their article. The views expressed in this Journal are those of the individual author and do not represent those of the Open University Geological Society. In the opinion of the author the description of ven- ues are accurate at the time of going to press; the Open University Geological Society does not accept respon- sibility for access, safety considerations or adverse conditions encountered by those visiting the sites. ISSN 0143-9472 Editor: Jane Clarke OUGS Journal 24(2) © Copyright reserved Symposium Edition 2003 email: [email protected] Cover illustration: Thin sections of several different habits of barite. Photographs: Jane Clarke. Botryoidal barite Acicular barite Poikilotopic barite Mag 538; ppl. Mag 549; xpl. Mag 530; xpl. Bladed barite (white) Botryoidal barite Spherulitic barite Mag 580; ppl. Mag 538; xpl Mag 584; xpl. Fasicular-optic barite Banded barite Banded barite Mag 549; xpl. Mag 538; xpl. Mag 538; ppl. Committee of the Open University Geological Society 2003 Executive Committee Members President: Professor Chris Wilson, Department of Earth Sciences, The Open University, Milton Keynes. MK7 6AA Chairman: David Maddocks Secretary: Linda Fowler Treasurer: Jane Michael Membership Secretary: Christine Arkwright Newsletter Editor: David Jones Information: Martin Elsworth Events Officer: Jan Ashton-Jones Sales Manager: Penny Widdison Non-voting postholders Gift Aid: Ann Goundry Journal Editor: Jane Clarke Archivist/Review Officer: Elizabeth Maddocks Minutes secretary: Roger Baker OUSA Representative: Norma Rothwell OUSA Deputy Representative: John Leahy Branch Organisers East Anglia: Wendy Hamilton East Midlands: Glynis Sanderson East Scotland: Anne Burgess Gogledd Cymru: Rachel Atherton Ireland: John Leahy London: Sue Vernon Mainland Europe: Annette Kimmich Northumbria: Pam Sidgwick North West: Alan Diggles Oxford: Sally Munnings Severnside: Philip Clark South East: Yvonne Lewis-Cutt South West: Mike Hermolle Walton Hall: Linda McArdell Wessex: George Raggett West Midlands: Chris Gleeson West Scotland: Stuart Fairley Yorkshire: Barbara Norton Past Presidents of the OUGS 1973-4 Prof Ian Gass 1985-6 Dr Peter Skelton 1997-8 Dr Dee Edwards 1975-6 Dr Chris Wilson 1987-8 Mr Eric Skipsey 1999-0 Dr Peter Sheldon 1977-8 Mr John Wright 1989-90 Dr Sandy Smith 2001-2 Dr Bob Spicer 1979-80 Dr Richard Thorpe 1991-2 Dr David Williams 2003- Prof Chris Wilson 1981-2 Dr Dennis Jackson 1993-4 Dr Dave Rothery 1983-4 Prof Geoff Brown 1995-6 Dr Nigel Harris Vice Presidents of the OUGS Dr Evelyn Brown Dr Michael Gagan Setting the scene: the geological framework and history of Northumbria Paul F V Williams, Staff Tutor in Earth Science, The Open University in the North The ancient kingdom of Northumbria stretches from Berwick in By the close of the Lower Palaeozoic, deep sea sediments the north, westwards to the Pennine watershed on the Cumbrian deposited on the southern margin of an Iapetus Ocean separating border, and south to the Tees. Geographically it contains the high a northern Laurentian landmass from a southern Avalonian micro- Pennines in the west, the Simonside and Cheviot Hills to the continent were caught up in the final phase of the Caledonian north-west, the Northumberland and Durham coastal plains to the Orogeny. Ocean closing and collision along a continental margin east, and the Tees basin to the south. The purpose of this paper is subducting northwards under Laurentia finally resulted in what to present an overview of the geological structure and history of was to become an English landmass being welded to the Scottish this ancient kingdom. Those wishing a more detailed insight are continent to the north. During the Silurian, turbidites were referred to the significant reference work, "Robson’s Geology of deposited down the continental slope and out onto the floor of the Northeast England" (Johnson 1995), while guides to localities Iapetus Ocean during the later stages of subduction and closure, can be found in "Northumbria Rocks and Landscape"(Scrutton and formed part of an accretionary prism developing as the lead- 1995). The geological history of Northern England is also cov- ing edge of Avalonia moved northwards to collide eventually with ered in "The Geological History of the British Isles" (Hunter Laurentia. Remnants of this accretionary prism can now be found 2001) the text to accompany the Open University second level within the area of Northumbria as turbidite deposits in the vicin- geology residential school course SXR260. The reader is also ity of the Cheviot Hills, close to the Scottish border. During this directed to two other papers relating to the underlying geological final collision phase the sedimentary package on the accretionary controls that established the tectonic framework of the area prism became folded, fractured and metamorphosed as crustal (Leggett et al. 1979; Leeder 1982). thickening and shortening took place along a NE-SW trending suture line, and resulted in what is today the Southern Uplands. It Within the boundaries of Northumbria the rock record shows a was the structural NE-SW lineations inherited from this event that folded Lower Palaeozoic basement overlain by a cover of ORS, were subsequently to play a major part in controlling the geolog- Carboniferous, and Permo-Triassic sediments. Into this sedimen- ical development of Northumbria. tary pile Devonian and Lower Carboniferous intrusive and extru- sive igneous rocks have been introduced, together with a later Collision resulted in shortened, thickened and uplifted continen- phase of minor intrusives of Permo-Carboniferous age, and also tal crust, which was then intruded by a series of post-orogenic, some Tertiary intrusives. Finally the whole has been sculpted and post-collision granites, probably generated by adiabatic decom- draped by glacial activity in the Quaternary. pression as the hot crust was rapidly uplifted. The Weardale gran- ite, which underlies the central part of Northumbria, resulted Remnants of the Lower Palaeozoic basement can be seen to the from this magmatism, the intrusion being dated at around 390Ma. north in an area west of the Cheviot Hills, the Cheviots them- Further to the north-east corner of the region and northwards selves being the remains of an igneous complex of Lower Old across the border into Scotland, a combination of localised crustal Red Sandstone age. However, it is Carboniferous rocks that dom- extension and strike-slip movement along major Caledonide NE- inate Northumbria at outcrop, the gentle easterly tilt bringing pro- SW trending fault lines produced small pull-apart basins, acting gressively younger Carboniferous horizons to the surface coast- as sites for magma generation. Magma delivery was likely to wards. From an arcuate outcrop around the Cheviots to the north, have been facilitated by the fractures acting as conduits. the Lower Carboniferous rocks, striking NNE-SSW, form the Magmatism in Northumbria began with a phase of explosive vol- extensive high ground of the Pennine fells in the west of the area. canic activity in which were built up around 70m of pyroclastics, Upper Carboniferous rocks, with contiguous strike, occupy the from agglomerates containing rhyolite blocks, to fine ashes, and lower lying Northumberland coastal plain and the site of the for- are best developed to the west of the Cheviot summit. The next mer Northumberland and Durham Coalfield. The south-eastern phase saw eruptions of rhyolite which cap some of the high sum- part of the region, from the Durham coast south to the Tees basin mits to the west of the Cheviot. Finally a major phase of volcanic is underlain by Permian rocks, with a roughly N/S strike. The activity saw many flows of andesite erupted, some of which are lowest horizons form a prominent escarpment to the east of trachytic in character. In the last stage of evolution of this mag- Durham City. Early Permian igneous intrusives also occur in matic complex granite was intruded into the centre of the lava Northumbria, the Whin Sill being the biggest, both in terms of lat- pile, metamorphosing the surrounding andesites. Roof pendants eral extent and magma volume. It stretches from the high Pennine of metamorphosed lava can be found on the southern flanks of the fells in the south-west of the area, through west Northumberland, Cheviot, the summit itself composed of granite.