This article was published online on May 5, 2011. An error was subsequently identified in Table 1 footnote. This notice is included in the online and print version to indicate that both have been corrected on June 16, 2011.
Special Issue Article
Early Precambrian mafic dyke swarms from the Central Archaean Bastar Craton, India: geochemistry, petrogenesis and tectonic implications†
Article first published online: 5 APR 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Special Issue: The Indian Precambrian: correlation and connections
Volume 47, Issue 2-3, pages 144–160, March-June 2012
How to Cite
Srivastava, R. K. and Gautam, G. C. (2012), Early Precambrian mafic dyke swarms from the Central Archaean Bastar Craton, India: geochemistry, petrogenesis and tectonic implications. Geol. J., 47: 144–160. doi: 10.1002/gj.1302
- Issue published online: 4 APR 2012
- Article first published online: 5 APR 2011
- Manuscript Accepted: 15 FEB 2011
- Manuscript Received: 26 NOV 2010
- mafic dyke swarm;
- early Precambrian;
- Bastar craton;
The Archaean Bastar craton is known for the presence of different generations of mafic dykes. Less studied many NW-SE trending mafic dykes (intruded into the Archaean supracrustal rocks), encountered from the central part of the Bastar craton, are studied for their petrological and geochemical characteristics. There are many geological evidences which suggest emplacement of these mafic dykes in an intracratonic setting. Two distinct types of mafic dykes are recognized. Petrographically it is difficult to discriminate these two types. Many samples show metamorphic textures and amphibolites facies mineral assemblage but a few samples preserved original igneous texture and mineralogy. Major oxides show sub-alkaline thoeliitic basalt/basaltic andesite nature. High-Fe and high-Mg contents classify them as high-iron and high-magnesium tholeiites. They fall in the gabbronorite field on R1-R2 plot. Geochemical characteristics, particularly high-field strength and rare-earth elements, clearly distinguished them into two types: Group 1 and Group 2 mafic dykes. When compared with well-studied mafic dyke swarms of the Southern Bastar craton, the Group 1 is recognized as Meso-Neoarchaean sub-alkaline mafic dykes (BD1-CBC) and the Group 2 as Neoarchaean-Palaeoproterozoic boninite–norite mafic dykes (BN-CBC). The boninite–norite nature of the second group is also corroborated through immobile trace element ratios. BD1-CBC dykes are characterized by a relatively higher concentration of HFSE and REE in comparison to BN-CBC dykes. Some extent of crustal contamination is observed in BN-CBC dykes but BD1-CBC dykes do not show any indication of crustal contamination. Trace element modelling suggest that BD1-CBC mafic dykes are derived from a melt originated through ∼20% melting of a depleted mantle source, whereas BN-CBC mafic dykes are probably derived from a high-Mg magma generated through ∼25% melting of a refractory mantle source. Both melts have undergone 30–40% olivine fractionation before the emplacement. Geochemistry also points out involvement of a plume in the genesis of these mafic dykes. Copyright © 2011 John Wiley & Sons, Ltd.