Abstract

Mr D. B ridgwater said that the regional pattern of events described by the authors was of considerable interest and their approach had widespread application outside the Lewisian of north-west Scotland. Studies on a similar regional scale were in progress on the Pre-Cambrian rocks of Greenland (for the most recent summary of research, see the 1966 report of activities of the Geological Survey of Greenland, Rapp. Grønlands geol. Unders. 11 ). The major units recognized in West Greenland were: a large central segment, the last major thermal event of which occurred about 2500 m.y. ago, flanked by younger fold belts (the Nagssugtoquidian, 1650–1800m.y. to the north; and the Ketilidian 1500–1800 m.y. to the south). These major dividions corresponded closely in time to the early Scourian and Laxfordian of north-west Scotland. The main features of relevance to the present discussion were the large amounts of early rocks reworked in the younger fold belts and the prevalence of concordant anorthosites of igneous origin (Windley 1966, Rapp. Grønlands. geol. Unders. 11 ), which the speaker thought had probably been formed earlier than 2700 m.y. ago. Mapping of the Pre-Cambrian of south-east Greenland, which might eventually be expected to provide the best area for comparison with north-west Scotland, had only just started on a regional basis. Preliminary age-determinations (Wager & Hamilton Nature, Lond., 1964) suggested that the last major plutonic event in the Angmagssalik area took place about 1600 m.y. ago. It is already clear, however, that the area is structurally complex and probably contains

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.