![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
A plug-like mass of Karroo dolerite, situate in the Mount Currie district of East Griqualand, is described in detail. By collapse of the roof, large blocks of sediments, belonging to the Stormberg series, were immersed in the magma. Three phases of igneous activity contributed to the formation of the complex. The first magma was tholeiitic, rich in iron oxides, and intruded along an outer ring-dike. Cauldron subsidence within the ring-dike led to the intrusion of a large volume of olivine-dolerite magma. The final phase consisted of a magma which was relatively poor in olivine. It is represented by a few narrow dikes and thin sheets. Interaction of the olivine-dolerite magma with the enveloped sediments produced tholeiites, in which pigeonite occurs instead of olivine.