Accretionary Lapilli and Other Spheroidal Rocks from the Archaean Swaziland Supergroup, Barberton Mountain Land, South Africa

Abstract

Since the pioneering work of Hall (1918) spheroidal or “oolitic” rocks have been described by a number of authors from the rocks of the Swaziland Supergroup (3.3 – 3.6 b.y.). Accretionary lapilli were first recognized in them by Reimer (1967). An unusually conspicuous band between the Onverwacht and Fig Tree Group, together with several similar occurrences in the Onverwacht Group, was described as accretionary lapilli by Lowe and Knauth (1978). These and other spheroidal rocks are described in this paper, and the implications of their occurrence are discussed. While the larger occurrences are described in some detail, information on the smaller ones is compiled in Table 1.