Isotopic and Geochronologic Studies on Granites from the Ketilidian Mobile Belt of South Greenland

Research Article| March 01, 1974 Isotopic and Geochronologic Studies on Granites from the Ketilidian Mobile Belt of South Greenland O. VAN BREEMEN; O. VAN BREEMEN 1Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow, G75 OQU, Scotland Search for other works by this author on: GSW Google Scholar M. AFTALION; M. AFTALION 1Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow, G75 OQU, Scotland Search for other works by this author on: GSW Google Scholar J. H. ALLAART J. H. ALLAART 2The Geological Survey of Greenland, Østervoldgade 10, Copenhagen, Denmark Search for other works by this author on: GSW Google Scholar Author and Article Information O. VAN BREEMEN 1Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow, G75 OQU, Scotland M. AFTALION 1Scottish Universities Research and Reactor Centre, East Kilbride, Glasgow, G75 OQU, Scotland J. H. ALLAART 2The Geological Survey of Greenland, Østervoldgade 10, Copenhagen, Denmark Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1974) 85 (3): 403–412. https://doi.org/10.1130/0016-7606(1974)85<403:IAGSOG>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation O. VAN BREEMEN, M. AFTALION, J. H. ALLAART; Isotopic and Geochronologic Studies on Granites from the Ketilidian Mobile Belt of South Greenland. GSA Bulletin 1974;; 85 (3): 403–412. doi: https://doi.org/10.1130/0016-7606(1974)85<403:IAGSOG>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Two early granitic units from the Ketilidian mobile belt of south Greenland yield a combined U-Pb discordia age of 1,840 ± 25 m.y. that is believed to date the peak of metamorphism; U-Pb zircon and Rb-Sr whole-rock isochron ages from four late Ketilidian granitic units indicate a widespread intrusive episode at 1,780 ± 20 m.y. B.P. Rb-Sr mineral ages agree with many recently published K-Ar mineral ages that are clustered around 1,600 m.y. B.P. The Rb-Sr and K-Ar ages evidently refect the final cooling in the mobile belt. The low initial 87Sr/86Sr ratio for the early granites (0.7022 ± 0.0010 for the two units) is probably not significantly different from that of the later granites (0.7032 ± 0.0005 for the four units).Although field evidence suggests that the early Ketilidian granites were derived from older basement, the ages and Sr isotopic evidence do not confirm this. Different interpretations for the origin of the granites are presented, and, in each of these, the evidence points to extensive igneous differentiation that appears to be connected with large-scale remelting, crustal generation, and igneous activity in the North Atlantic and Baltic Shield regions between 1,950 and 1,700 m.y. ago. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.