Abstract

The end of the Saldanian magmatic event is marked by a short period of peraluminous silicic magmatism, evident as a series of ignimbrite flows, quartz porphyry and tuffisite intrusions. There is a close relationship between high-level granitic intrusions present as granite porphyries in the Langebaan area and the volcanic event. The subvolcanic-volcanic rocks under discussion ended the fourth and final phase of the Cape Granite Suite magmatism, thus starting and ending with a peraluminous phase. U-Pb ID-TIMS zircon age determinations on the second of three mappable ignimbrite flows yielded an age of 515.5 ± 3.1Ma. Two single zircon grains with 207Pb/ 206Pb ages of ~1875Ma and ~1575 Ma respectively are interpreted to represent xenocrysts extracted from older crust or from sedimentary contaminants.

You do not currently have access to this article.