Petrogenesis of syenites at a rifted continental margin: origin,contamination and interaction of alkaline mafic and felsic magmas in the Astrophyllite Bay Complex,East Greenland |
| |
| Authors: | Email author" target="_blank">M?S?RiishuusEmail author D?W?Peate C?Tegner J?R?Wilson C?K?Brooks T?E?Waight |
| |
| Institution: | (1) Department of Earth Sciences, University of Aarhus, 8000 Århus C, Denmark;(2) Danish Lithosphere Centre, Øster Voldgade 10, 1350 Copenhagen K, Denmark;(3) Department of Geoscience, University of Iowa, 121 Trowbridge Hall, Iowa City, IA 52242, USA;(4) Geological Institute, University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark |
| |
| Abstract: | The Astrophyllite Bay Complex in East Greenland (part of the Palaeogene North Atlantic Igneous Province) consists of an alkaline diorite plug, with detached trachyandesitic pillows, surrounded by co-magmatic syenite that was emplaced into Archaean basement. The diorite intrusion has yielded a 47.11 ± 0.68 Ma Rb-Sr isochron age. Saw-cut profiles through pillow-syenite-gneiss sections have been taken to resolve close spatial elemental and isotopic (Sr-Nd-Hf-Pb-O) variations. The diorite and syenite formed from alkaline basaltic, mantle-derived, melts with complex histories of prolonged assimilation and fractional crystallisation. Each evolved to different extents in separate magma chambers during the establishment of new plumbing systems in the Kangerlussuaq area. The diorite is dominated by lower crustal, granulite facies contamination, whereas the syenite shows evidence for greater degrees of upper crustal amphibolite facies contamination, indicating stalling and fractionation of magmas at different levels within the crust. The syenite and diorite magmas were subsequently emplaced as separate pulses into the basement gneisses at Astrophyllite Bay giving rise to superimposed local contamination trends between pillow/syenite and syenite/gneiss, respectively. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
