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Lithospheric Mantle Deformation beneath the Indian Cratons
The Journal of Geology
|October 13, 1999
Summary
Ancient Indian continental roots show significant deformation, challenging long-held stability theories. This study reveals a dynamic thermal structure beneath the Indian shield, indicating recent geodynamic activity rather than Precambrian stability.
Area of Science:
- Geophysics
- Tectonics
- Earth Sciences
Background:
- The stability of deep continental roots beneath Archean-Early Proterozoic terrains is debated.
- It is unclear if these ancient terrains have remained stable since the Precambrian or been affected by recent plate motions.
Purpose of the Study:
- To investigate the thermal structure beneath the cratonic regions of the Indian shield.
- To assess the deformation of deep continental roots and their stability.
Main Methods:
- Analysis of lithospheric thickness variations across Indian cratons (e.g., Singhbhum, Dharwars).
- Determination of asthenosphere depth, reduced heat flow, and Moho temperatures.
Main Results:
- Lithospheric thickness varies significantly, from 65 km to 148 km.
- Average asthenosphere depth is 104 km, shallower than in other stable continental areas.
- Indian cratons exhibit higher average reduced heat flow (approx. 35 mW/m2) and Moho temperatures (approx. 550°C) compared to global counterparts.
Conclusions:
- The study indicates large-scale deformation of the cratonic mantle lithosphere beneath the Indian shield since the Mesoproterozoic.
- Geodynamic causes have led to this deformation, challenging the concept of stable, ancient continental roots.