British regional geology: The Palaeogene volcanic districts of Scotland

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The British regional geology: The Palaeogene volcanic districts of Scotland has been converted to a series of articles for this wiki. The book is available for purchase at the BGS Online Shop Its full reference is:

Emeleus, C H, and Bell, B R. 2005. British regional geology: The Palaeogene volcanic districts of Scotland. Fourth edition. Keyworth, Nottingham: British Geological Survey.

British regional geology: The Palaeogene volcanic districts of Scotland (Fourth edition). P749532.

Contents

Introduction

Summary of geology

Pre-Mesozoic

Archaean
Torridonian
Moine Supergroup
Dalradian Supergroup
Lower Palaeozoic
Caledonian igneous rocks
Old Red Sandstone
Carboniferous
Permian
Intrusions of Carboniferous and Permian age

Mesozoic

Triassic
Jurassic
Cretaceous

Pre-Palaeogene structure

Early Palaeozoic and older structures
Late Palaeozoic to Mesozoic structures

Palaeogene igneous geology: regional setting

Timing and igneous stratigraphy

Palaeogene lava fields and associated sedimentary rocks

Petrography of the lavas
Field characteristics of the lavas
Lava sequences
Eigg Lava Formation
Skye Lava Group
Mull Lava Group

Dykes, dyke swarms and volcanic plugs

Dyke swarms
Volcanic plugs

Sills and sill-complexes

Little Minch Sill-complex
Loch Scridain Sill-complex, Mull
Holy Island and Dippin sills, Arran
Microgranitic and rhyolitic sills, south Arran
Composite sills of Arran and south Bute
Tighvein Intrusion-complex, Arran
Raasay Sill
Gars-bheinn Ultrabasic Sill, Skye
Other sills

Central complexes

St Kilda
Skye
Rum
Ardnamurchan
Mull
Blackstones Bank
Arran
Ailsa Craig
Rockall

Magmas

Early concepts
Major-element compositions
Contamination processes
Depth of magma generation
Ultrabasic and basic magmas of the central complexes
Minor intrusions
Silicic rocks
Magma mixing

Palaeogene and later structure

Major faults
Structure of the lava fields
Structures associated with the central complexes

Late Palaeogene and Neogene

Quaternary

Pre-Late Devensian glaciations
Dimlington Stadial
Windermere Interstadial
Loch Lomond Stadial
Sea level changes
Other Late-glacial and postglacial features

Economic geology

References

Foreword to the fourth edition

Uniquely in the British Regional Geology series, the boundaries of the area covered by this volume are not easy to define, either geographically or geologically. In broad terms it covers the northern islands of the Inner Hebrides, with parts of the adjoining mainland, plus the Isle of Arran in the Firth of Clyde. This area spans several geological terranes in which most of the pre-Mesozoic rocks are already well described in other volumes of this series. It is characterised by extensive outcrops of igneous rocks of early Palaeogene age (formerly Tertiary) and by locally thick sequences of Mesozoic sedimentary rocks that, in many places, owe their preservation to a protective cover of Palaeogene lavas. Consequently, the descriptions in this volume concentrate largely upon the geological processes and products of the Mesozoic and Cainozoic eras. The term ‘Tertiary’ is no longer approved, having been replaced formally in both chronostratigraphical and lithostratigraphical nomenclature by the Palaeogene and Neogene systems/periods. However, it continues to be used informally by some authors.

The first edition of this book, by J E Richey, was published in 1935. It was revised and updated mainly by the original author in the second edition of 1948 and by A G MacGregor and F W Anderson in the third edition of 1961. At the time of the last edition, many of the tools and techniques now taken for granted in geological and geophysical research were in their infancy, and the concepts of global tectonics were hardly known. The purpose of this completely rewritten new edition is to provide an up-to-date, generalised account of the geology that is comprehensible and of interest to the informed amateur, undergraduate and professional geologist, planner or civil engineer. While the emphasis is on the fundamentals of the regional geology and, in particular, what can be seen in the field, this account also demonstrates how some of the major advances in our understanding of the area have been made possible through the application of new techniques and concepts, and for some of these this region has provided a crucial test bed. This is most apparent in the extensive geochemical investigations of the igneous rocks, which have contributed so much to our knowledge of magma generation and evolution, both in the Hebrides and worldwide. For this reason a chapter has been devoted to the subject of magmas, which the authors feel is necessary for a complete discussion of the processes involved in the evolution of this igneous province of worldwide importance.

Although an enormous amount of specialised research has been conducted in the area in the last 40 years by university workers from around the world, there has been no systematic resurvey by Geological Survey staff. However, following in the footsteps of Alfred Harker of Cambridge University in the early 20th century, resurveys of the Small Isles, parts of Skye and to a lesser extent Ardnamurchan and northern Mull have been conducted on behalf of the British Geological Survey by university staff. Almost all of this work has been by Henry Emeleus of Durham University and Brian Bell of Glasgow University, and we are very fortunate that they have pooled their collective experience, gained from this and other work in the area, to produce this new edition.

David Falvey, PhD. Director. British Geological Survey.

Acknowledgements

This edition of British regional geology: the Palaeogene volcanic districts of Scotland has been completely rewritten by C H Emeleus of the University of Durham and B R Bell of the University of Glasgow, under contract to the British Geological Survey as part of the University Collaboration Programme (Consultancy agreement number GA/94E/19). The authors would like to acknowledge assistance from J D Hudson of the University of Leicester with the Mesozoic chapter, J W Merritt and J D Peacock of the BGS with the Quaternary chapter and K Hitchen of the BGS for advice on offshore Palaeogene igneous rocks. Information from the glass-sand mine at Loch Aline was kindly provided by Tilcon (Scotland) Ltd. M A Hamilton, University of Toronto, provided the U-Pb ages quoted in Table 8.

Scientific editing and compilation on behalf of the BGS was by D Stephenson, and manuscript review by P Stone; the series editor is A A Jackson. Figures were produced by BGS Cartography, Edinburgh: page setting by A Hill.

Photographs were taken by the authors, unless otherwise stated in the captions; they have been deposited in the BGS National Archive of Geological Photographs.