Crystallization of amphiboles in the Kid volcanic complex, Southern Sinai, Egypt implications for magma evolution /
The Kid volcanics consist of three main suites namely, basaltic andesite-andesite (BA-A), trachydacitedacite (TD-D) and rhyodacite-alkali rhyolite (RD-AR). Microprobe analyses of phenocrysts and groundmass of the amphiboles from rocks of these volcanic suites are presented in this paper. Amphiboles...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
University of Szeged, Department of Mineralogy, Geochemistry and Petrology
Szeged
1995
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| Sorozat: | Acta mineralogica-petrographica
36 |
| Kulcsszavak: | Kőzettan, Ásványtan, Földtan |
| Tárgyszavak: | |
| Online Access: | http://acta.bibl.u-szeged.hu/24821 |
| Tartalmi kivonat: | The Kid volcanics consist of three main suites namely, basaltic andesite-andesite (BA-A), trachydacitedacite (TD-D) and rhyodacite-alkali rhyolite (RD-AR). Microprobe analyses of phenocrysts and groundmass of the amphiboles from rocks of these volcanic suites are presented in this paper. Amphiboles from BA-A suite range from tschermakite phenocryst cores to ferro tschermakitic hornblende phenocryst rims and groundmass. TD-D suite has ferroan pargasite phenocrysts and ferroan pargasitic hornblende groundmass. Amphiboles from RD-AR suite range from kaersutite and ferroan pargasite phenocryst cores to magnesian hastingsitic hornblende phenocryst rims and magnesian hastingsite groundmass. The amphiboles of Kid volcanics are Ti-rich, calcic-type. In most cases, amphibole phenocrysts from BA-A and RD-AR suites have the same evolution, reflect their cognate magmas. Moreover, both the TD-D and RDAR suites have close genetic relationship. The progressive evolutionary trend from phenocryst cores to phenocryst rims and groundmass and from intermediate (BA-A) to felsic (RD-AR) suite are responsible for the magmatic evolution of the Kid volcanic suites. In contrast, the concentration of amphibole composition as a function of pressure and temperature suggest an opposite trend for the grade of metamorphism of these suites. These calcic amphiboles are expected to be formed at high temperature (~700— 1000 "C) and low pressure (-0.2-3 Kb.) conditions. |
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| Terjedelem/Fizikai jellemzők: | 17-33 |
| ISSN: | 0365-8066 |