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The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa
Includes bibliographical references.
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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Department of Geological Sciences
2015
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| _version_ | 1867613290900750336 |
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| access_status_str | Open Access |
| author | Moore, Andrew Edward |
| author2 | Erlank, A J |
| author_browse | Erlank, A J Moore, Andrew Edward |
| author_facet | Erlank, A J Moore, Andrew Edward |
| author_sort | Moore, Andrew Edward |
| collection | Thesis |
| description | Includes bibliographical references. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/12595 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:33:48.261Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2015 |
| publishDateRange | 2015 |
| publishDateSort | 2015 |
| publisher | Department of Geological Sciences |
| publisherStr | Department of Geological Sciences |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/12595 The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa Moore, Andrew Edward Erlank, A J Includes bibliographical references. Early Tertiary olivine melilitites and associated non-diamondiferous kimberlites occur in two pipe clusters in the Namaqualand and Bushmanland regions of South Africa. The more northerly cluster is centred about the town of Gamoep and the second is located south of Garies. The olivine melilitites are characterized by olivine phenocrysts which exhibit a broad range in composition on the scale of individual hand specimens. It is possible to distinguish four petrographically and chemically distinct olivine populations in both the northern and southern pipes studied: (a) Rare anhedral or subhedral olivines that display marked disequilibrium features with the surrounding matrix and which are characterized by having high iron and extremely low nickel contents (referred to as HILN olivines) relative to the remaining olivines in the same rock; (b) euhedral and often skeletal (hopper) olivines that are richer in Mg and Ni than HILN olivines in the same rock. Some of the euhedral olivines show abnormal zonation patterns ("unusual" hoppers). Hopper and HILN olivines contain fluid and carbonate inclusions which apparently record the separation of a vapour phase and an immiscible carbonate liquid during magma ascent: (c) large rounded olivines (megacrysts) up to 40 mm across. Individuals are chemically homogeneous, but megacrysts from the same pipe collectively define a trend of decreasing Mg with Ni (F092, 0.36% Ni to F075, 0.17% Ni). The most fayalitic megacrysts are depleted in Mg and Ni relative to the hopper olivines in the same rock. [d] In addition to these main populations, there also occur rare magnesium-rich (F091) anhedral olivines which show strained extinction and are believed to be xenocrysts. 2015-03-13T14:06:03Z 2015-03-13T14:06:03Z 1979 Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/12595 eng application/pdf Department of Geological Sciences Faculty of Science University of Cape Town |
| spellingShingle | Moore, Andrew Edward The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa |
| thesis_degree_str | Doctoral |
| title | The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa |
| title_full | The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa |
| title_fullStr | The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa |
| title_full_unstemmed | The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa |
| title_short | The geochemistry of the Olivine Melilitetes and related rocks of Namaqualand Bushmanland, South Africa |
| title_sort | geochemistry of the olivine melilitetes and related rocks of namaqualand bushmanland south africa |
| url | http://hdl.handle.net/11427/12595 |
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