Preliminary geochemical data for dolerite dykes and sills of the southern part of the Etendeka Igneous Province
- Marsh, Julian S, Erlank, Anthony J, Duncan, Andrew R
- Authors: Marsh, Julian S , Erlank, Anthony J , Duncan, Andrew R
- Date: 1991
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/132133 , vital:36803
- Description: Over the last 15 years systematic geochemical and petrological investigation of the igneous rocks of the Early Cretaceous - Late Jurassic Etendeka Igneous Province of northwestern Namibia have focused on the tholeiitic basaltic lavas and interbedded silicic volcanic rocks and the large central subvolcanic complexes of Brandberg, Erongo, Okenyenya, Messum, Doros and Cape Cross. Previously these rocks were grouped into the Karoo Volcanic Province of South Africa, but in view of the distinct age difference between the igneous rocks of the Etendeka region and Karoo rocks occurring elsewhere in southern Africa , we propose to regard them as constituting a separate Etendeka Igneous Province which exhibits a close lithological, geochemical and temporal correlation with the Parana Flood Basalt Province of South America.
- Full Text:
- Date Issued: 1991
- Authors: Marsh, Julian S , Erlank, Anthony J , Duncan, Andrew R
- Date: 1991
- Language: English
- Type: text , report
- Identifier: http://hdl.handle.net/10962/132133 , vital:36803
- Description: Over the last 15 years systematic geochemical and petrological investigation of the igneous rocks of the Early Cretaceous - Late Jurassic Etendeka Igneous Province of northwestern Namibia have focused on the tholeiitic basaltic lavas and interbedded silicic volcanic rocks and the large central subvolcanic complexes of Brandberg, Erongo, Okenyenya, Messum, Doros and Cape Cross. Previously these rocks were grouped into the Karoo Volcanic Province of South Africa, but in view of the distinct age difference between the igneous rocks of the Etendeka region and Karoo rocks occurring elsewhere in southern Africa , we propose to regard them as constituting a separate Etendeka Igneous Province which exhibits a close lithological, geochemical and temporal correlation with the Parana Flood Basalt Province of South America.
- Full Text:
- Date Issued: 1991
REE fractionation and Ce anomalies in weathered Karoo dolerite
- Authors: Marsh, Julian S
- Date: 1991
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145819 , vital:38469 , https://doi.org/10.1016/0009-2541(91)90099-D
- Description: Analyses of samples from a weathering profile on Karoo dolerite allow elements to be divided into three groups depending on their behaviour. Si, K, Na, Mg, Ca, Sr, Ba and V are mobilized and removed from weathered products. Fe, Al. Ti, Zr, Hf, Zn, Cu, Sc, Co and Ni are immobile. REE, Y, and to a lesser extent Cr, are mobile and redistributed within the profile without a net loss of these elements from the profile. Large positive Ce anomalies are developed in oxidized weathered products by preferential leaching of the other REE's. Negative Ce anomalies and REE enrichment is a feature of less altered dolerite.
- Full Text: false
- Date Issued: 1991
- Authors: Marsh, Julian S
- Date: 1991
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/145819 , vital:38469 , https://doi.org/10.1016/0009-2541(91)90099-D
- Description: Analyses of samples from a weathering profile on Karoo dolerite allow elements to be divided into three groups depending on their behaviour. Si, K, Na, Mg, Ca, Sr, Ba and V are mobilized and removed from weathered products. Fe, Al. Ti, Zr, Hf, Zn, Cu, Sc, Co and Ni are immobile. REE, Y, and to a lesser extent Cr, are mobile and redistributed within the profile without a net loss of these elements from the profile. Large positive Ce anomalies are developed in oxidized weathered products by preferential leaching of the other REE's. Negative Ce anomalies and REE enrichment is a feature of less altered dolerite.
- Full Text: false
- Date Issued: 1991
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