Neoproterozoic magmatism in eastern Himalayan terrane
Yuhua Wang1, Lingsen Zeng2, Li-E Gao2
1Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China; Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, and College of Marine Geosciences, Ocean University of China, Qingdao 266100, China; Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Sciences, Peking University, Beijing 100871, China.
Science Bulletin
|January 20, 2023
Summary
Neoproterozoic magmatism in the Himalayas occurred between 850-800 million years ago. This ancient magma originated from melting of Earth
Area of Science:
- Geochronology and geochemistry of Tibetan gneisses.
Background:
- Investigating the geological history of the Himalayan terrane.
- Understanding Neoproterozoic magmatic events and their origins.
Purpose of the Study:
- To geochronologically and geochemically characterize granitic gneisses in Cuona, south Tibet.
- To determine the timing and source of Neoproterozoic magmatism in the Himalayan region.
- To explore the potential link between magmatism and the breakup of the Rodinia supercontinent.
Main Methods:
- Zircon geochronology (U-Pb dating) to determine formation and metamorphic ages.
- Lu-Hf isotopic analyses on zircon for crustal source information.
- Whole-rock geochemical analysis to classify rock compositions and tectonic setting.
Main Results:
- Protoliths of granitic gneisses formed at 808.8–816.4 Ma and 855.8 Ma.
- A metamorphic event was recorded at 739.4 Ma.
- Negative εHf(t) values (-9.0 to -4.2) and model ages (1965–2228 Ma) indicate derivation from ancient crustal sources.
- Geochemistry reveals K-rich calc-alkaline nature of the gneisses.
Conclusions:
- The Himalayan terrane experienced significant magmatism between 850-800 Ma during the Neoproterozoic.
- Neoproterozoic granitic magmas were sourced from partial melting of ancient crustal materials.
- This magmatism may be linked to thermal events associated with the Rodinia supercontinent's breakup.
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