element ransport

• Main Authors: David A. Rae, Ian M. Coulson, Andrew, D. Chambers
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: apatite; metasomatism; rare-earth elements; cathodoluminescence; Igaliko; Gardar; South Greenland; Greenland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.618.1743; http://www.minersoc.org/pages/Archive-MM/Volume_60/60-398-207.pdf

The North Q6roq syenite centre forms part of the Gardar Province of South Greenland. Extensive metasomatism, associated with the evolution of syenitic magmas, has resulted in redistribution of the rare-earth elements (REE), originally concentrated by magmatic processes, in both the syenites and surrounding granite-gneiss and quartzite country rocks. An important host for REE is apatite which can occur irl significant quantities. Metasomatic apatites how complex, concentric, but irregular patterns of zonation, clearly seen using CL and BSE imaging. This zonation is related to successive pulses of metasomatising fluids. Electron microprobe analysis confirms the presence of significant quantities of REE in the apatites. The dominant 2+ O+ 3+ 4+ cation exchange mechanism proposed is Ca + P ~-- ~ REE + Si. In contrast o apatites from the nearby Ilfmaussaq intrusion, there is no significant Na present in the structure and exchange reactions involving Na + and REE 3+ for Ca 2+ have not occurred. Apatites from the quartzite are fluor-apatites, while those from the granite-gneiss are more Cl-rich. These differences reflect the fact that granite-gneiss apatites are original and modified by metasomatism, whereas, those in the quartzite are metasomatic n origin. REE were probably transported as carbonate, fluoride or fluor-carbonate complexes, and reflect the activity of a F-rich, CO ~-rich fluid phase.