The structural evolution of England and Wales during the Carboniferous was primarily a consequence of an oblique (dextral) collision between Gondwana and Laurussia (2507). Several phases can be recognized. The Rhenohercynian Ocean opened during Early–Mid Devonian regional bacK–Arc transtension between Avalonia and Armorica (1), possibly associated with northward-directed subduction along the southern margin of Armorica. A narrow seaway floored by oceanic crust developed, extending across southwest England, northern France and Germany. Cessation of the subduction, associated with the Ligerian orogenic phase of central Europe, resulted from the collision of the Iberian and Armorican microplates (1). During the Late Devonian, transpressive closure of this restricted ocean, associated with the Bretonian orogenic phase, may have occurred in response to short-lived southward-directed subduction of the Rhenohercynian oceanic plate beneath Armorica.
A return to northward-directed subduction of the Theic oceanic plate along the southern margin of Iberia/Armorica (1) resulted in a Late Devonian–Early Carboniferous phase of bacK–Arc extension within the Avalonian part of the Laurussian plate (2507). The resultant N–S rifting affected all of central and northern England and North Wales, initiating development of a series of graben and half-grabens,
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The Geology of England and Wales
This second edition of The Geology of England and Wales is considerably expanded from its predecessor, reflecting the increase in our knowledge of the region, and particularly of the offshore areas. Forty specialists have contributed to 18 chapters, which cover a time range from 700 million years ago to 200 million years into the future. A new format places all the chapters in approximately temporal order. Both offshore and economic geology now form an integral part of appropriate chapters.
Most of England and Wales is formed from part of a single terrane, Avalonia, and its pre-Cambrian (Neoproterozoic) history is preserved in patches. However the time intervals from the Cambrian to the present day are well represented in our sequences and the Cambrian, Ordovician, Silurian and Devonian systems were all defined here. William Smith's map of England and Wales was the world's first geological map of a country and the British Geological Survey's copy is reproduced in the introductory chapter. This chapter, by the editors, consists of a broad overview aimed particularly at the non-specialist while guiding the reader towards the appropriate succeeding chapters. The volume concludes with a look at the future, from the short-term effects of climate change and sea-level rise to the position of our region in a possible plate tectonic configuration 200 million years hence.
While the authors have taken a ‘dynamic’ view of the evolution of the area over geological time, they have also ensured that the geological evidence on which the interpretations are based is reviewed thoroughly. Hence the volume provides a valuable resource for both Earth scientists and the broader community.