Application of 55 multi-dimensional tectonomagmatic discrimination diagrams to Precambrian belts

Abstract

Fifty-five new multi-dimensional diagrams, mostly based on log-ratio transformations, were used to decipher tectonic settings for 17 cases of Precambrian belts in Canada, the USA, Poland, Finland, Jordan, Democratic Republic of Congo and Zambia, China, and India. The results of different sets of diagrams for basic-ultrabasic, intermediate, and acid magmas were generally internally consistent. Possible reasons for some inconsistencies may be related to the use of a sample group of mixed ages because of their uncertainties, extreme element mobility caused by metamorphism especially of high-grade type, analytical data quality, different petrogenetic processes for basic to acid magmas such as mantle versus crustal origin, and some deficiencies that still exist in the multi-dimensional diagrams. To partly overcome the last problem, one new multi-dimensional diagram is proposed and used to discriminate mid-ocean ridge and oceanic plateau settings.

Keywords:

• tectonic setting
• Archaean
• Proterozoic
• log-ratio transformation
• geochemistry

Acknowledgements

We are grateful to Dr Ram Chandra and Dr Vinod K. Singh, organizers of the 3rd International Conference on Precambrian Continental Growth and Tectonism (PCGT-2013), Jhansi, India, for inviting us to present this work as an invited talk in this conference and to Prof. Robert Stern, Editor-in-Chief, International Geology Review, for approving a special issue for publication of peer-reviewed papers. Also, our sincere gratitude goes to the students of Bundelkhand University, Jhansi, India (Shaktiman, Sanjeet, Mahesh, and Ashish) for providing us wonderful hospitality. The world map (Figure 2) in Corel was kindly provided by John Armstrong, which we used to show the locations of our case studies. We are extremely grateful to Prof. John Shervais and an anonymous reviewer for numerous helpful comments, which enabled us to significantly improve our presentation.

Additional information

Funding

SPV is thankful to DGAPA-UNAM PAPIIT project IN104813 (Mexico) for partial support. Both SKV and EPO are grateful to the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP, Brazil) [grants 2012/07243-3 and 12/15824-6] and Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, CNPq, Brazil [grant 308424/2011-5].