The Lower Palaeozoic Igneous Rocks and Quaternary Deposits of the Area Between Haweswater and Shap (Part of Sheets 30 and 39, England and Wales)
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The Lower Palaeozoic igneous rocks and Quaternary deposits of the area between Haweswater and Shap (part of Sheets 30 and 39, England and Wales) Integrated Geoscience Surveys (North) Research Report RR/02/02 NATURAL ENVIRONMENT RESEARCH COUNCIL BRITISH GEOLOGICAL SURVEY Research Report RR/02/02 The Lower Palaeozoic igneous rocks and Quaternary deposits of the area between Haweswater and Shap (part of Sheets 30 and 39, England and Wales) The National Grid and other Ordnance Survey data are used D Millward with the permission of the Controller of Her Majesty’s Stationery Office. Ordnance Survey licence number GD 272191/2003. Cover illustration Haweswater and Harter Fell. Bibliographical reference MILLWARD, D. 2003. The Lower Palaeozoic igneous rocks and Quaternary deposits of the area between Haweswater and Shap (part of Sheets 30 and 39, England and Wales). British Geological Survey Research Report, RR/02/02. 48 pp. ISBN 0 85272 418 7 Copyright in materials derived from the British Geological Survey's work is owned by the Natural Environment Research Council (NERC) and/or the authority that commissioned the work. You may not copy or adapt this publication without first obtaining NERC permis- sion. Contact the BGS Copyright Manager, Keyworth, Nottingham. You may quote extracts of a reasonable length without prior permission, provided a full acknowledge- ment is given of the source of the extract. © NERC 2003. All rights reserved Keyworth, Nottingham British Geological Survey 2003 BRITISH GEOLOGICAL SURVEY ACKNOWLEDGEMENTS The full range of Survey publications is available from the BGS The farmers, landowners and the Lake District National Park Sales Desks at Nottingham, Edinburgh and London; see contact are thanked for their co-operation and assistance during the details below or shop online at www.geologyshop.com survey. I gratefully acknowledge the help and encouragement The London Information Office also maintains a reference collec- given by my colleagues in the field and during preparation of tion of BGS publications including maps for consultation. this report. In particular I would like to thank Drs Brett The Survey publishes an annual catalogue of its maps and other Beddoe-Stephens and Derek Woodhall, now no longer with publications; this catalogue is available from any of the BGS BGS, for all their help and discussions. I also thank Dr Emrys Sales Desks. Phillips for help with the contact metamorphism section. The British Geological Survey carries out the geological survey NOTES of Great Britain and Northern Ireland (the latter is an agency service for the government of Northern Ireland), and of the sur- All grid references given in brackets [] throughout the rounding continental shelf, as well as its basic research projects. report are within the 100 km square NY. It also undertakes programmes of British technical aid in geology Numbers preceded by the letter E refer to registered num- in developing countries as arranged by the Department for bers in the British Geological Survey sliced rock collection. International Development and other agencies. The British Geological Survey is a component body of the Natural In this report the word ‘district’ refers to the whole area Environment Research Council. covered by the report. The term ‘pyroclastic density current’ is used here as a British Geological Survey offices term for the whole spectrum of volcanic density currents that includes what are conventionally referred to as pyro- clastic surges and pyroclastic flows as its end members Keyworth, Nottingham NG12 5GG (Druitt, 1998). ຜ 0115–936 3100 Fax 0115–936 3200 e-mail: sales @bgs.ac.uk www.bgs.ac.uk Shop online at: www.geologyshop.com Murchison House, West Mains Road, Edinburgh EH9 3LA ຜ 0131–667 1000 Fax 0131–668 2683 e-mail: [email protected] London Information Office at the Natural History Museum (Earth Galleries), Exhibition Road, South Kensington, London SW7 2DE ຜ 020–7589 4090 Fax 020–7584 8270 ຜ 020–7942 5344/45 e-mail: [email protected] Forde House, Park Five Business Centre, Harrier Way, Sowton, Exeter, Devon EX2 7HU ຜ 01392–445271 Fax 01392–445371 Geological Survey of Northern Ireland, 20 College Gardens, Belfast BT9 6BS ຜ 028–9066 6595 Fax 028–9066 2835 Maclean Building, Crowmarsh Gifford, Wallingford, Oxfordshire OX10 8BB ຜ 01491–838800 Fax 01491–692345 Sophia House, 28 Cathedral Road, Cardiff, CF11 9LJ ຜ 029–2066 0147 Fax 029–2066 0159 Parent Body Natural Environment Research Council, Polaris House, North Star Avenue, Swindon, Wiltshire SN2 1EU ຜ 01793–411500 Fax 01793–411501 Foreword This report describes the bedrock and Quaternary geology, milestone in the survey of the Lake District. The area lies and the geological structure of the Borrowdale Volcanic within the 1:50 000 Series geological sheets 30 (Appleby) Group and associated intrusive rocks of the area between the and 39 (Kendal), and encompasses parts of 1:10 000 geo- Haweswater reservoir, Swindale, Wet Sleddale and Shap in logical sheets NY 41 NE, and SE, NY 50 NW, and NY 51 the eastern Lake District, Cumbria. In Section 11 new NW, SW and SE. This report is best read in conjunction evidence is presented relevant to the interpretation of the with these large-scale maps. form of the unconformity at the base of the Windermere The geology of the Borrowdale Volcanic Group in areas Supergroup; the significance of pyroclastic rocks at the base adjoining the west and south-west of that covered by this of the Yarlside Volcanic Formation within the Dent Group, report is described by Beddoe-Stephens (2000a), Woodhall the lowest part of the Windermere Supergroup, is discussed. (2000a) and Johnson (2001). The Haweswater intrusions that Section 16 comprises information on the Quaternary deposits crop out around the Haweswater Reservoir are described by in the area. Millward and Beddoe-Stephens (1998). The Skiddaw Group, Field work was carried out between 1997 and 1999 as which lies to the north and east of the area, has been part of the Lake District Regional Geological Survey described by Bell (1997). Full reference to these accounts is Project under the leadership of Dr P Stone. The given towards the end of this Research Report. Haweswater and Shap area is the final part of the volcanic This report has been reviewed by Dr D G Woodhall and outcrop to be resurveyed, representing a significant edited by Dr P Stone. iii Contents Foreword iii 14 Metamorphism 31 14.1 Contact metamorphic aureole of the Shap Summary v Granite 31 1 Introduction 1 15 Mineralisation 35 1.1 Geological succession 1 1.2 Previous research 1 16 Quaternary deposits 36 16.1 Glacial deposits 36 2 Birker Fell Formation 6 16.2 Post-glacial deposits 37 2.1 Frith Crag Member 7 Information sources 38 3 Whelter Knotts Formation 8 Maps 38 3.1 Powley's Hill Member 9 Other information 38 3.2 Pinnacle Howe Member 9 Material collections 38 3.3 Interpretation 10 References 39 4 Mardale Formation 11 4.1 Brown Howe Member 11 4.2 Rowantreethwaite Member 12 Tables 4.3 Unnamed pyroclastic units 13 4.4 Gouther Crag Member 14 1 General stratigraphy of the Lake District Lower 4.5 Great Ladstones Member 14 Palaeozoic rocks present on 1:50 000 geological sheets Appleby (30) and Kendal (39) 3 5 Froswick Formation 15 2 Borrowdale Volcanic Group stratigraphy in the area between Haweswater and Shap, with key localities and 6 Seathwaite Fell Formation 16 summary interpretation of the volcanism, depositional processes and environment 4 7 Wet Sleddale Formation 17 3 Comparison of previous lithostratigraphical classifica- tions of the Borrowdale Volcanic Group in the Appleby 8 Lincomb Tarns Formation 18 district with that used in this report 5 4 Lower Palaeozoic intrusive rocks in the Haweswater to 9 Undifferentiated volcaniclastic rocks 19 Shap area belonging to the Caledonian Igneous Supersuite 24 10 Contemporaneous andesite sheets 20 5 Mineralisation in the Haweswater and Shap area 35 11 The unconformity between the BVG and the overlying Windermere Supergroup 22 Figures 11.1 Pyroclastic rocks at the base of the Yarlside Volcanic Formation 22 1 Principal geographical and geological features of the Haweswater and Shap area 2 12 Intrusive rocks 23 2 Ni-Zr and Cr-Y plots for sills from the middle and 12.1 Haweswater intrusions (Ordovician) 23 upper parts of the Mardale Formation and from the 12.2 Basalt dykes (Ordovician) 23 uppermost part of the Borrowdale Volcanic Group in 12.3 Shap pluton (Early Devonian) 23 the Shap Fells 20 12.4 Porphyritic microgranite and microgranodiorite 3 Summary of the main structural features of the dykes (Early Devonian) 23 Haweswater and Shap area 27 12.5 Lamprophyre dyke (Early Devonian) 25 4 The Shap Pluton and its metamorphic aureole, showing mineral assemblages and cleavage pattern 32 13 Structure 26 5 Illustration of the relative ages of the mineral as- 13.1 Summary of structural history 26 semblages seen in the Borrowdale Volcanic Group 13.2 Faulting 26 rocks in the aureole of the Shap Pluton 34 13.3 Cleavage 30 iv Summary This report describes the geology of the igneous and asso- A substantial volume of andesite sills was intruded into ciated rocks of the area between the Haweswater Reservoir the volcanic pile. Late in the volcanic cycle, plugs and and the Shap Fells in the north-eastern part of the Lake masses of dolerite and gabbro were also emplaced to form District National Park. Resurvey of the Borrowdale Vol- the subvolcanic Haweswater intrusions. canic Group began in 1981 and this report covers the final Throughout the Lake District the Borrowdale Volcanic part of the outcrop to be examined. Group is separated from the overlying Windermere Super- The major volcanic succession in the Lake District is the group by a major unconformity.