U-Pb geochronology of the Eocene Kaerven intrusive complex, East Greenland: constraints on the Iceland hotspot track during the rift-to-drift transition

作者：Thorarinsson Sigurjon B^*; Holm Paul M; Tappe Sebastian; Heaman Larry M; Praegel Niels Ole

来源：Geological Magazine, 2016, 153(1): 128-142.

DOI：10.1017/S0016756815000448

• Kangerlussuaq
• zircon
• syenite
• post-break-up
• North Atlantic Igneous Province

Several major tholeiitic (e.g. the Skaergaard intrusion) and alkaline (e.g. the Kangerlussuaq Syenite) intrusive complexes of the North Atlantic Large Igneous Province are exposed along the Kangerlussuaq Fjord in East Greenland. The Kaerven Complex forms a satellite intrusion to the Kangerlussuaq Syenite and includes early tholeiitic gabbros and a series of cross-cutting alkaline intrusions ranging from monzonite to alkali granite. The alkaline intrusions cut the gabbros, and are cut by the outer nordmarkite zone of the Kangerlussuaq Syenite. This study presents the first U-Pb zircon ages from the alkaline units of the Kaerven Complex. Fourteen multi-grain zircon fractions have been analysed by thermal ionization mass spectrometry (TIMS). Absolute age differences could not be resolved between the different units, suggesting a relatively rapid succession of intrusions between c. 53.5 and 53.3 Ma. Our compilation of precise radiometric age data shows that most of the alkaline magmatism in the Kangerlussuaq Fjord occurred prior to 50 Ma. Moreover, pre-50 Ma alkaline intrusions and lavas show a SSE-younging trend, which is interpreted as the track of the Iceland hotspot during the rift-to-drift transition of the North Atlantic.

• 出版日期2016-1