400-mile fossil volcano chain
August 3 , 2025
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- A 400-mile (700 km) long fossilized volcanic arc formed 800 million years ago was found under South China’s Yangtze Block.
- Formed during Rodinia’s breakup, it resulted from flat-slab subduction, causing magma to rise and solidify deep below.
- Airborne magnetic sensing and boreholes up to 6 km deep revealed volcanic rocks with arc-related geochemistry.
- Uranium-lead dating confirmed formation between 770 and 820 million years ago in the early Neoproterozoic era.
- The unusually wide arc (up to 50 km) reshapes the understanding of the early continental crust evolution.

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