Neoproterozoic and Cambro-Ordovician magmatism: episodic growth and reworking of continental crust, Himachal Himalaya, India

ABSTRACT

U-Pb SHRIMP and LA-MC-ICP-MS zircon dates from Dalhousie and Dhauladhar granite yield weighted mean ages of 900 to 700 Ma for magmatic cores. The rim has an age of 460 Ma age, representing the time of reworking of early Neoproterozoic bodies during Cambro-Ordovician time. The plutons are composed of granite, monzogranite, and granodioritic having a peraluminous character with pronounced Eu anomaly. Higher Rb content and Rb/Sr ratio along with REE enrichment in Dalhousie granite show that the body is more evolved than Dhauladhar granite. New U-Pb data from Dalhousie and Dhauladhar areas suggest that Cambro-Ordovician continental magmatism took place within the Greater India by reworking of already existing Neoproterozoic granite. These two magmatic episodes can be correlated with the amalgamation of Gondwanaland over granite that formed during the Rodinia break-up.

Graphical abstract

KEYWORDS:

• Greater India
• Neoproterozoic magmatism
• Cambro-Ordovician magmatism
• SHRIMP
• LA-MC-ICP-MS

Highlights

1. Granite yield magmatic cores of Neoproterozoic age with rim ages of Cambro-Ordovician time indicating reworking of granites during Cambro-Ordovician Time.

2. These zircons also form a source of detrital Neoproterozic zircon within Greater India domain.

3. The two magmatic episodes indicate the involvement of Greater India domain during the breakup of Supercontinent Rodinia and amalgamation of Gondwanaland.

Acknowledgments

A Ph.D. grant to Rimpi at the Department of Earth Sciences, IIT Roorkee from the University Grants Commission (Grant no. 6405-14-044-428), New Delhi is highly acknowledged. SS thanks Heads, Department of Earth Sciences, and Institute Instrumentation Center, IITR Roorkee for extending the facilities and the Ministry of Earth Sciences for a research project (grant no. MOES/16/40/09-RDEAS). The authors are also thankful to Director, Wadia Institute of Himalayan Geology, Dehra Dun for his allowing the facility of the LA-MC-ICPMS Facility. Help rendered by Pulok Mukherjee and Saurabh Singhal of Wadia Institute of Himalayan Geology is also appreciated. SS also thank the Department of Science and Technology, New Delhi for the BOYSCAST fellowship during the year 2000–2001 with Prof. Mark E. Barley at Centre for Global Metallogeny, Nedlands, Perth for logistic support. Zircon analyses were carried out on a SHRIMP-II operated by a consortium consisting of Curtin University of Technology, Perth, the Geological Survey of Western Australia, and the University of Western Australia, with the support of the Australian Research Council. The manuscript and figures improved drastically after suggestions made by Robert Stern and Richard Palin.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

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Additional information

Funding

This work was supported by the University Grant Commission, New Delhi [6405-14-044-428]; Ministry of Earth Sciences, New Delhi [MoES/P.O.(Geosci)/27/2014].