| A consideration of Rheic margin tectonics reveals several possible source terranes for silicic explosive volcanism. |
| Additional weak silicic solutions formed thin encrustations of quartz on the calcite in delicate encrustation pseudomorphs. |
| In geothermal waters, hydrogen sulphide, silicic acid, and boric acid may also be important. |
| The revised age for the Jozini Formation rhyolites is also of significance for petrogenetic models proposed for the Karoo silicic magmatism. |
| In both areas, the silicic magmatism is thought to have been a result of intrusion of mantle-derived mafic magmas into extending crust. |
| Salic magmas ranged widely from silicic to feldspathoidal and from peraluminous to peralkaline. |
