Phase Equilibrium Constraints on Intensive Crystallization Parameters of the Ilimaussaq Complex, South Greenland |
| |
| Authors: | MARKL GREGOR; MARKS MICHAEL; SCHWINN GREGOR; SOMMER HOLGER |
| |
| Institution: | INSTITUT FÜR MINERALOGIE, PETROLOGIE UND GEOCHEMIE, EBERHARD-KARLS-UNIVERSITÄT, WILHELMSTRASSE 56, D-72074 TÜBINGEN, GERMANY |
| |
| Abstract: | The 1·13 Ga Ilímaussaq intrusive complex, SouthGreenland, is composed of various types of alkali granite andsilica-undersaturated alkaline to agpaitic nepheline syenitesrelated to three subsequently intruded magma batches. Mineralchemistry indicates continuous fractionation trends within eachrock type, but with distinct differences among them. The last,peralkaline magma batch is the most fractionated in terms ofXFemafic mineral, feldspar composition and mineral assemblage.This indicates that an evolving magma chamber at depth discontinuouslyreleased more highly fractionated alkaline melts. Fluid inclusionsin some sodalites record a pressure drop from 3·5 to1 kbar indicating that crystallization started during magmaascent and continued in the high-level magma chamber. On thebasis of phase equilibria and preliminary fluid inclusion data,crystallization temperature drops from >1000°C (augitesyenite liquidus) to <500°C (lujavrite solidus) and silicaactivity decreases from |
| |
| Keywords: | |
| 本文献已被 Oxford 等数据库收录！ |
|
