『Abstract
Following the discovery of diamonds in river deposits in central
South Africa in the mid nineteenth century. It was a Kimberley
where the volcanic origin of diamonds was first recognized. These
volcanic rocks, that were named “kimberlite”, were to become the
corner stone of the economic and industrial development of southern
Africa. Following the discoveries at Kimberley, even more valuable
deposits were discovered in South Africa and Botswana in particular,
but also in Lesotho, Swaziland and Zimbabwe.
A century of study of kimberlites, and the diamonds and other
mantle-derived rocks they contain, has furthered the understanding
of the processes that occurred within the sub-continental lithosphere
and in particular the formation of diamonds. The formation of
kimberlite-hosted diamond deposits is a long-lived and complex
series of processes that first involved the growth of diamonds
in the mantle, and later their removal and transport to the earth's
surface by kimberlite magmas. Dating of inclusions in diamonds
showed that diamond growth occurred several times over geological
time. Many diamonds are of Archean age and many of these are peridotitic
in character, but suites of younger Proterozoic diamonds have
also been recognized in various southern African mines. These
younger ages correspond with ages of major tectono-thermal events
that are recognized in crustal rocks of the sub-continent. Most
of these diamonds had eclogitic, websteritic or lherzolitic protoliths.
In southern Africa, kimberlite eruptions occurred as discrete
events several times during the geological record, including the
Early and Middle Proterozoic, the Cambrian, the Permian, the Jurassic
and the Cretaceous. Apart from the Early Proterozoic (Kuruman)
kimberlites, all of the other events have produced deposits that
have been mined. It should however be noted that only about 1%
of the kimberlites that have been discovered have been successfully
exploited.
In this paper, 34 kimberlite mines are reviewed with regard to
their geology, mantle xenolith, xenocryst and diamond characteristics
and production statistics. These mines vary greatly in size, grade
and diamond-value, as well as in the proportions and types of
mantle mineral suites that they contain. They include some of
the world's richest mines, such as Jwaneng in Botswana, to mines
that are both small and marginal, such as the Frank Smith Mine
in south Africa. They include large diatremes such as Orapa and
small dykes such as those mined at Bellsbank, Swartruggens and
near Theunissen. These mines are all located on the Archaean Kalahari
Craton, and it is apparent that the craton and its associated
sub-continental lithosphere played an important role in providing
the right environment for diamond growth and for the formation
of the kimberlite magmas that were to transport them to the surface.
Keywords: Diamond; Kimberlite; Diatreme; Pipe; Dyke; Mantle-xenolith;
Diamond-inclusion 』
1. Introduction
2. History and discovery of kimberlite
2. Some definitions
4. Summary of kimberlite geology
4.1. Kimberlite definition
4.2. Group 1 and 2 kimberlites
4.3. Kimberlite lithofacies nomenclature
4.4. Kimberlite pipe formation models
4.4.1. Magmatic models
4.4.2. Phreatomagmatic model
5. Large mines
5.1. The Kimberley mines
5.1.1. Kimberley mine
5.1.1.1. Discovery
5.1.1.2. Geology
5.1.1.3. Mantle xenoliths and diamond inclusions
5.1.1.4. Diamonds
5.1.1.5. Production
5.1.2. De Beers mine
5.1.2.1. Discovery
5.1.2.2. Geology
5.1.2.3. Xenoliths
5.1.2.4. Diamonds
5.1.2.5. Diamond inclusions
5.1.2.6. Production
5.1.3. Bultfontein mine
5.1.3.1. Discovery
5.1.3.2. Geology
5.1.3.3. Xenoliths
5.1.3.4. Diamonds
5.1.3.5. Diamond inclusions
5.1.3.6. Production
5.1.4. Dutoitspan mine
5.1.4.1. Discovery
5.1.4.2. Geology
5.1.4.3. Diamond inclusions
5.1.4.4. Diamonds
5.1.4.5. Production
5.1.5. Wessselton mine
5.1.5.1. Discovery
5.1.5.2. Geology
5.1.5.3. Xenoliths
5.1.5.4. Diamond inclusions
5.1.5.5. Diamonds
5.1.5.6. Production
5.2. Koffiefontein mine
5.2.1. Discovery
5.2.2. Geology
5.2.3. Xenoliths
5.2.4. Diamond inclusions
5.2.5. Diamonds
5.2.6. Production
5.3. Jagersfontein mine
5.3.1. Discovery
5.3.2. Geology
5.3.3. Xenoliths
5.3.4. Diamond inclusions
5.3.5. Diamonds
5.3.6. Production
5.4. Premier (Cullinan) mine
5.4.1. Discovery
5.4.2. Geology
5.4.3. Xenoliths
5.4.4. Diamond inclusions
5.4.5. Diamonds
5.4.6. Production
5.5. Finsch mine
5.5.1. Discovery
5.5.2. Geology
5.5.3. Xenoliths
5.5.4. Diamond inclusions
5.5.5. Diamonds
5.5.6. Production
5.6. Orapa mine
5.6.1. Discovery
5.6.2. Geology
5.6.3. Xenoliths
5.6.4. diamond inclusions
5.6.5. Diamonds
5.6.6. Production
5.7. Letlhakane mine
5.7.1. Discovery
5.7.2. Geology
5.7.3. Xenoliths
5.7.4. Diamond inclusions
5.7.5. Production
5.8. Jwaneng mine
5.8.1. Discovery
5.8.2. Geology
5.8.3. Xenoliths
5.8.4. Diamond inclusions
5.8.5. Diamonds
5.8.6. Production
5.9. Venetia mine
5.9.1. Discovery
5.9.2. Geology
5.9.3. Xenoliths
5.9.4. Diamond inclusions
5.9.5. Production
5.10. Damtshaa mine
5.10.1. Discovery
5.10.2. Geology
5.10.3. Production
5.11. Murowa
5.11.1. Location and discovery
5.11.2. Geology
5.11.3. Production
6. Small mines
6.1. Frank Smith
6.1.1. Discovery
6.1.2. Geology
6.1.3. Xenoliths
6.1.4. Diamonds
6.1.5. Production
6.2. Newlands
6.2.1. Location
6.3. Geology
6.3.1. Xenoliths
6.3.2. Diamonds
6.3.3. Production
6.4. Voorspoed
6.4.1. Location and discovery
6.4.2. Geology
6.4.3. Diamonds
6.4.4. Production
6.5. Crown/Lace
6.5.1. Discovery and history
6.5.2. Geology
6.5.3. Xenoliths
6.5.4. Diamonds
6.6. Kaalvallei (Samada mine)
6.6.1. Location and history
6.6.2. Geology
6.6.3. Xenoliths
6.7. Monastery
6.7.1. Location and history
6.7.2. Geology
6.7.3. Xenoliths
6.7.4. Diamond inclusions
6.7.5. Diamonds
6.8. Letseng-la-terae
6.8.1. Location and history
6.8.2. Geology
6.8.3. Xenoliths
6.8.4. Diamond inclusions
6.8.5. Diamonds
6.9. The Oaks
6.9.1. Location and discovery
6.9.2. Geology
6.9.3. Production
6.10. River Ranch
6.10.1. Location and discovery
6.10.2. Geology
6.10.3. Mantle zenoliths/xenocrysts
6.11. Diamond inclusions
6.11.1. Production
6.12. Dokolwayo
6.12.1. Discovery and location
6.12.2. Geology
6.12.3. Xenoliths
6.12.4. Diamond inclusions
6.12.5. Production
6.13. Mines of the Boshof District
6.14. Roberts Victor
6.14.1. Location
6.14.2. Geology
6.14.3. Xenoliths
6.14.4. Diamond inclusions
6.14.5. Diamonds
6.14.6. Production
6.15. New Elands
6.15.1. Geology
6.15.2. Diamonds
6.15.3. Production
6.16. Blaauwbosch
6.16.1. Geology
6.16.2. Diamonds
6.16.3. Production
6.17. Loxtondal cluster
6.17.1. Location
6.17.2. Geology
6.17.3. Diamonds
6.17.4. Production
6.18. The Bellsbank group
6.18.1. Location and discovery
6.18.2. Geology
6.18.3. Xenoliths
6.18.4. Diamond inclusions
6.18.5. Production
6.19. The DoornkloofSover or Ardo group
6.19.1. Location
6.19.2. Geology
6.19.3. Production
6.20. The Swartruggens group
6.20.1. Location
6.20.2. Geology
6.20.3. Xenoliths
6.20.4. Diamonds
6.20.5. Production
6.21. The Marsfontein-Klipspringer group
6.21.1. Location
6.21.2. Geology
6.21.3. Production
6.22. The Theunissen group
6.22.1. Location
6.22.2. Geology
6.22.3. Xenoliths, diamond-inclusions and diamonds
6.22.4. Production
7. Discussion
7.1. Origin and emplacement of primary diamond deposits
7.2. Economic significance
8. Conclusions
Acknowledgements
References