A laterally extensive geochemical discontinuity in the subcontinental Gondwana Lithosphere
- Authors: Erlank, Anthony J , Duncan, Andrew R , Marsh, Julian S , Sweeney, R J , Hawkesworth, C J , Milner, Simon C , Miller, R McG , Rogers, N W
- Date: 1988
- Language: English
- Type: text , abstracts
- Identifier: http://hdl.handle.net/10962/131678 , vital:36710
- Description: Cox et al. (1967) first delineated the existence of two major geochemical provinces in the Karoo basalts of southern Africa. Tholeiitic basalts in Zimbabwe are highly enriched in incompatible trace elements and constitute the "northern province". In contrast, basalts from Lesotho and from the southern segment of the Lebombo monocline have lower or “normal” abundances of these elements and were regarded as a "southern province'. Recent work has established that this change in composition takes place relatively rapidly in the Central Lebombo.
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- Date Issued: 1988
Distribution and petrogenesis of the basic rocks of the Etendeka Formation of northwestern Namibia
- Authors: Marsh, Julian S , Duncan, Andrew R , Milner, Simon C , Erlank, Anthony J
- Date: 1988
- Language: English
- Type: text , abstracts
- Identifier: http://hdl.handle.net/10962/131667 , vital:36709
- Description: The igneous rocks which comprise the Etendeka Formation in northwestern Namibia cover an area of 78 000 km² and consist dominantly of interbedded basalts and quartz latites, with minor latites. They are spatially associated with, and intruded by, two suites of dolerites. The rocks of the Etendeka Formation are included in the Karoo Igneous Province but differ from most other Karoo volcanics with respect to their younger age (Cretaceous) and aspects of their mineralogy and geochemistry.
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- Date Issued: 1988
The late Archaean Dominion Group, South Africa: petrogenesis of flood-type basalts and their mantle sources
- Authors: Marsh, Julian S , Rogers, N W , Bowen, M P , Bowen, T B
- Date: 1988
- Language: English
- Type: text , abstracts
- Identifier: http://hdl.handle.net/10962/131690 , vital:36721
- Description: The Dominion group has an age of 2.7 - 2.8 Ga and is the earliest of the cover sequences overlying the granite greenstone terrane in the western part of the Archaean Kaapvaal Craton, southern Africa. The Dominion group is largely built of volcanic rocks and is preserved over an area of 15,000 km² with a maximum thickness of 2.7 km.
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- Date Issued: 1988
Karoo basalts of the Springbok Flats: geochemistry and correlation
- Authors: Marsh, Julian S
- Date: 1984
- Language: English
- Type: text , abstracts
- Identifier: http://hdl.handle.net/10962/131634 , vital:36706
- Description: Karoo basalts underlie an area of about 3750 km2 of the Springbok Flats. Four boreholes were logged and sampled for detailed petrographic and chemical analysis. The Springbok Flats basalt's chemical composition is compared with those of the Sabie River Formation of the Lebombo and the Lesotho type of the Central Karoo area. Sr- and Nd- isotopic data were also used in determining the chemical composition. The study also allows the geographical extent of the incompatible element-enriched clan of Karoo Lavas to be refined.
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- Date Issued: 1984