Petrogenesis of Cogenetic Silica-Oversaturated and-Undersaturated Syenites by Periodic Recharge in a Crustally Contaminated Magma Chamber: the Kangerlussuaq Intrusion

• Main Authors: East Greenland, Morten S. Riishuus, David W. Peate, Christian Tegner, J. Richardwilson, C. Kent Brooks
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2004
• Subjects: Greenland; Kangerlussuaq
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.562.8556; http://petrology.oxfordjournals.org/content/49/3/493.full.pdf

Greenland displays concentric zonation from quartz-rich nordmar-kite (quartz syenite) at the margin, through pulaskite, to foyaite (nepheline syenite) in the centre; modal layering and igneous lamination are locally developed but there are no internal intrusive contacts. This is an apparent violation of the phase relations in Petrogeny’s Residua System. We propose that this intrusion is layered, grading from quartz syenite at the bottom to nepheline syenite at the top. Mineral and whole-rock major and trace element data and Sr^Nd^Hf^Pb isotope data are presented that provide constraints on the petrogenesis of the intrusion. Radiogenic isotope data indicate a continuously decreasing crustal com-ponent from the quartz nordmarkites (87Sr/86Sr 07061; eNdi 23; eHfi 52; 206Pb/204Pbmeas 1698) to the foyaites (87Sr/86Sr 07043^07044; eNdi 38^49; eHfi107^111; 206Pb/204Pbmeas1778^1788); the foyaites are dominated by a