Title: Geochemistry, petrogenesis and tectonic significance of the Newer Dolerites from the Singhbhum Orissa craton, eastern Indian shield
Abstract: Abstract The Singhbhum Orissa craton, eastern India contains rocks as old as 3.6 Ga. The Newer Dolerites occur in two distinct orientations (NE/SW and NW/SE) in the Singhbhum Granitoid Complex (SBGC). These dikes are mostly tholeiites and quartz-normative dolerites associated with subordinate norites. We recognize three geochemical groups of the Newer Dolerites that were emplaced in the SBGC. Group I dikes contain lower SiO2 ( < 53.29%) and higher Mg #, Ni and Cr than group II dikes. Group III dikes have higher SiO2 than groups I and II. A few investigated samples show boninitic geochemical features. They have high-MgO (>8%), high-SiO2 (>52%) and low-TiO2 ( ≤ 0.5%) bulk-rock compositions. The main feature of the Newer Dolerite spidergrams is enrichment in the large-ion lithophile elements (LILE, e.g. Rb, K and Ba) relative to high field-strength elements (HFSE), resulting in high LILE/HFSE ratios. These geochemical characteristics suggest that the Newer Dolerites are subduction related. High La/Ta ratios (21–66) support a non-plume source. Therefore, we conclude that the Newer Dolerites show geochemical signatures similar to those of back-arc basalts. Keywords: Newer DoleritesPrecambrian crustal evolutionX-ray fluorescencefractional crystallization Acknowledgements We thank the chairman, Department of Geology, Aligarh Muslim University for providing facilities to carry out the work. We are highly thankful to the Director, NGRI, for permission to analyse these samples. Thanks are due to Mohd Yousuf, Mushtaq Ahmad, Zahoor-ul-Islam, and Bilal Ahmad for fruitful discussion and suggestions. Constructive comments and valuable suggestions from an anonymous reviewer are duly acknowledged.
Publication Year: 2009
Publication Date: 2009-04-22
Language: en
Type: article
Indexed In: ['crossref']
Access and Citation
Cited By Count: 6
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot