The roles of primary kimberlitic and secondary Dwyka glacial sources in the development of alluvial and marine diamond deposits in Southern Africa

The drainage of Africa since the Cretaceous

“…It has shown considerable changes in its pattern and extent since the Cretaceous (Dollar, 1998), and these have been the subject of considerable recent research because old river courses may be sources of diamonds (Moore and Moore, 2004;Jacob et al, 1999).…”

The Mesozoic–Cenozoic interior sag basins of Central Africa: The Late-Cretaceous–Cenozoic Kalahari and Okavango basins

“…Fossil wood constrains the age of the gravels to the Upper Cretaceous (Partridge, 1998;Bamford, 2000;Ward et al, 2004). Although clasts from the channels were originally interpreted as indicating a flow direction towards the southeast (Partridge, 1998), Moore and Moore (2004) believe that flow might have been northwards. Recent work by Ward et al (2004) appears to confirm a northward flow direction, with clast lithologies, fining direction, imbrication of clasts and ilmenite chemistry being cited as evidence.…”

“…It is possible that these gravels represent the original east to west course of the Kalahari River and the northward flowing, left-bank tributaries of the Kalahari River respectively. A Cretaceous drainage model for South Africa proposed by Moore and Moore (2004) also shows rivers flowing northwestwards into the Kalahari River system. Moore and Moore (2004) do not believe, however, that the Karoo River existed and not only question the lack of related Cretaceous palaeochannels or gravel terraces associated with a Karoo River, but also believe much of the mineral-chemical evidence for the Karoo River (de Wit, 1993(de Wit, , 1999 can be explained by erosion of Dwyka sedimentary rocks.…”

“…A Cretaceous drainage model for South Africa proposed by Moore and Moore (2004) also shows rivers flowing northwestwards into the Kalahari River system. Moore and Moore (2004) do not believe, however, that the Karoo River existed and not only question the lack of related Cretaceous palaeochannels or gravel terraces associated with a Karoo River, but also believe much of the mineral-chemical evidence for the Karoo River (de Wit, 1993(de Wit, , 1999 can be explained by erosion of Dwyka sedimentary rocks. The evidence for the existence of a Karoo River in the Early to Late Cretaceous is still convincing, however (de Wit, 1993(de Wit, , 1999, and the northwards flow of the Mahura Muthla system can be more easily explained by the presence of a watershed coinciding with the position of the pre-Karoo Cargonian Highlands (Visser, 1987) and separating the drainages of the Karoo and Kalahari river systems (Fig.…”

Overview of Diamond Resources in Africa

“…These include a Cretaceous aged palaeo-Orange or 'Karoo' River, which entered the ocean near the site of the current OlifantsSout drainages (Dingle and Hendey, 1984;de Wit, 1999), and a Dwyka Group glacial source of diamonds (Maree, 1987;Moore and Moore, 2004), aided by numerous short-reach rivers draining to the west of the escarpment. Bluck et al (2005) support the Karoo River or some form of craton-derived river system, existing from 117.5-103 Ma.…”