Radiating 1.0 Ga Mafic Dyke Swarms of Eastern Brazil and Western Africa: Evidence of Post-Assembly Extension in the Rodinia Supercontinent? |
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摘 要: |
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收稿时间: | 5 August 1999 |
Radiating 1.0 Ga Mafic Dyke Swarms of Eastern Brazil and Western Africa: Evidence of Post-Assembly Extension in the Rodinia Supercontinent? |
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Authors: | LC Correa-Gomes EP Oliveira |
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Institution: | 1. South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China;2. School of Ecological Technology and Engineering, Shanghai Institute of Technology, Shanghai 201418, China;3. Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-environmental and Soil Sciences, Guangzhou 510650, China;4. Graduate School of Chinese Academy of Sciences, Beijing 100039, China |
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Abstract: | Several mafic dyke swarms of similar composition and age (tholeiite- ca.1.0 Ga) occur on both sides of the Atlantic Ocean in eastern South America and western Africa. When assembled to their pre-drift position in the Mesozoic, the Brazilian coastal dyke province of Bahia, and the African dykes in Cameroun (Ebolowa suite) and Congo (Comba and Sembe-Ouesso provinces) define a giant radiating pattern (1200 km × 800 km) similar to other dyke swarms elsewhere associated with large-scale continental rifting. Magma flow indicators of the Brazilian dykes and branching propagation styles of their African counterparts indicate that the dyke conduits were fed with magmas diverging from a source beneath the long axis of the Meso-Neoproterozoic West-Congolian Basin in Africa. There, MORB-like metabasalts have been described in the La Bikossi Group of the Mayombian Supergroup. Whether the rifting event and intrusion of dyke swarms were triggered or not by a mantle plume beneath part of the Rodinia subcontinental lithosphere remain to be confirmed. |
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Keywords: | Mafic dykes palaeocontinental reconstruction Rodinia supercontinent |
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