Geological Society, London, Memoirs
Geological Society, London, Memoirs; 2003; v. 28;
p. 5-11;
DOI: 10.1144/GSL.MEM.2003.028.01.02
© 2003 Geological Society of London
Chapter 2 Regional Structural Framework
The pre-Permian geology of northern England and Wales (Wills 1973, 1978; Whittaker 1985; BGS 1985) is divided by lineaments and faults into a series of major terranes (Fig. 4). Turner (1949) and Wills (1973, 1978) realized that old Caledonian faults had exerted considerable influence on the geometry and orientation of subsequent tectonic features and recognized the presence of a triangular shaped platform with a thin, flatlying undeformed Palaeozoic cover underlying the English Midlands (Figs 4 and 5). The platform is bounded on its southern side by the Variscan thrust front, on its northwestern side by the Longmynd Fault and to the northeast by a NW-SE-trending lineament which Turner (1949) and Wills (1973) placed in different locations. The Longmynd Fault, in the NW, separates the platform from the deformed and cleaved Palaeozoic sediments of the Welsh Caledonides. The NE boundary represents a major lineament which separates the platform from a hidden East Midlands Caledonide belt, again with deformed and cleaved Lower Palaeozoic sediments. In this study, the boundary of Turner (1949) was found to be the more appropriate. This triangular platform is now referred to as the Midlands Microcraton (Pharaoh et al. 1987).
Turner (1949) compared the northern triangular apex of the microcraton with the Hindu Kush and suggested that the NE Caledonian trend in Wales could be traced in an arc around the apex into the East Midlands Caledonides (Figs 4 and 5). This outer arc continues northwards as far as the Iapetus suture, which separates the Welsh and East Midlands Caledonides from the Laurentian
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