Thread by @rapiduplift

Aaravali.

Not Rajasthan. But Maharashtra.

Thread- Hot Springs of Konkan. Geologic Significance

One interesting feature of Konkan coastal belt is the presence of hot water springs arranged in a fairly narrow linear belt from north of Mumbai to Ratnagiri area in the south. They occur somewhat midway between the W. Ghat Escarpment and the coast.

Few names from north to south- Vajreshwari, Akoli kund, Ganeshpuri, Pali, Dasgaon, Unhere, Tural, Aaravali, Rajapur. Satellite image shows the area between Dabhol and Ratnagiri. Hot springs are located within the oval.

What is so special about this area? See the map. Black lines r fracture zones, trending N-S, NW-SE and NE-SW. Hot springs r located in the vicinity of these fractures roughly within the oval. Area is again between Dabhol and Ratnagiri, but this relationship applies elsewhere.

Water temperatures are between 50 deg C to 60 deg C. Analysis shows significant levels of radon gas at measured sites near Tural. Presence of radon hints at the reason why there are hot springs here. It points to deep circulation of water...

Radon is not present is high quantities in Deccan basalt. It forms by decay of Uranium in granitic rocks. Radon emission here imply that these fractures cut through the basalt pile and penetrate the > 2 billion yr old granitic rocks (richer in Uranium) underlying these basalts.

Such deep fracture systems have allowed groundwater to circulate to great depths, get heated and form a hydrothermal circulation system. The cross section shows fracture/fault systems of the coastal region cutting across basalts and penetrating the underlying granitic basement.

What makes the water hot? Deccan volcanism ended 60 million yrs ago, so unlikely there is any magma underneath. Rocks get hotter at depths due to natural geothermal gradient. Plus some faulting may be causing friction between blocks, heating those zones.

These fractures and faults are a legacy of the breakup of the India with Madagascar and later Seychelles during and post Deccan volcanism .. 68 -60 million years ago. This rifting caused tearing of the Indian crust resulting in oriented fracture systems.

The schematic shows the evolution of the Western Ghat escarpment and the coastal region. Earlier the escarpment was a cliff formed by faulting. Subsequent erosion has caused it to retreat eastwards, creating a coastal plain. Orange lines mark the highly fractured Indian crust.

Next time you visit Konkan and take a dip in the invigorating warm waters, remember the deep geological forces of continental separation, heat flow and ground water circulation systems that arise consequently.

end thread....