| Autor: |
D. L. Reid, Chris Harris, Robert B. Trumbull, Catherine G. Curtis, Coenraad de Beer, Rolf L. Romer |
| Rok vydání: |
2009 |
| Předmět: |
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| Zdroj: |
11th SAGA Biennial Technical Meeting & Exhibition 'Ancient Rocks to Modern Techniques' (Swaziland, South Africa 2009) |
| Popis: |
Koegel Fontein is a 30 km diameter anorogenic igneous complex that intruded Namaqualand gneisses during the initial phase of break-up of Africa and South America. It is notable for the presence of quartz porphyry dykes that formed from low-δ 18 O magmas. Many of the igneous rocks show petrographic evidence for alteration and have had their δ 18 O values lowered by fluid-rock interaction at high temperatures. Partial melting and/or assimilation of this material produced the low- δ 18 O magmas. Whole-rock δD and δ 18 O values indicate equilibrium with meteoritc water with a δ 18 O value around -10 ‰, which is abnormally negative given the relatively low latitude at the time of intrusion. A combination of an elevated volcanic edifice and the ‘continental effect’ is the most likely explanation. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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