Orcadian Basin issue. Editorial introduction

Abstract

This part of the Scottish Journal of Geology contains a group of papers relating to the geology of the Orcadian Basin. The idea for a thematic part of the Journal came from T. R. Astin who convened the Orcadian Basin Meeting held at Cambridge in September, 1984. The majority of the papers in this part were presented at the Cambridge meeting. The meeting provided a timely forum for a variety of perspectives on the Orcadian Basin. The term Orcadian Basin is generally used with reference to the exposures of Old Red Sandstone (ORS) from the southern shores of the Moray Firth, westwards to the Inverness area and north to Caithness, Orkney and Shetland. The eastern margin of the Orcadian Basin lies offshore and cannot be defined. Palaeogeographic maps with the Orcadian Basin labelled as extending from Scotland to Norway ([Ziegler 1982][1]) give a very simplified impression of ORS sedimentation. Throughout the area numerous depocentres probably existed; each of which could have received combinations of Lower, Middle and Upper ORS fill. Mykura ([1983][2]) gives a general account of the ORS of the Orcadian Basin which would introduce the reader to the papers in this issue. Details of stratigraphy are given by [Westoll (1977)][3]. Subsidence areas and structural style vary considerably between Lower, Middle and Upper ORS. Several Lower ORS basin depocentres existed (Parnell; Richards) and deformation and faulting affected these rocks prior to deposition of the Middle ORS sequence. The thick dominantly lacustrine, Middle ORS sequence is seen to have greater . . . [1]: #ref-5 [2]: #ref-2 [3]: #ref-4