What Raj Bhavan Rests On

An article written by me for the Maharashtra Governer's Mansion Complex's Newsletter 'Aaple Raj Bhavan' (Your Raj Bhavan)


There is also a piece written on the article in Marathi by one of the editors of Maharashtra Times, Suhas Phadke.  See the link: http://maharashtratimes.indiatimes.com/articleshow/13323645.cms. In this article he adds a paragraph at the beginning and at the end to give context and the rest is well-paraphrased from my article.


Raj Bhavan, like much of Maharashtra and parts of neighbouring states, rests on a few kilometers thick basaltic lava flows erupted directly from the Earth’s mantle at about 65 million years ago (see Figure 1). These black colored basaltic rocks, which form the Western Ghats and the Deccan Plateaux, cover an area of about 500,000 sq km in much of Maharashtra and parts of Gujarat and are known as the Deccan Traps.  There are only a dozen or so such flood basalt provinces known in the world. 

A view of eroded basalt ledges off Raj Bhavan guesthouse. Can you find these rocks?

Based on the Plate Tectonics concept in geology, the Indian peninsula was in the southern hemisphere at the location of the present Réunion island east of Madagascar at that time of the eruption of these basalts and was moving northward after Gondwanaland (the geologic term for the southern conglomeration of continents named after the Gond tribe in India) fragmented in the Jurassic period around 150 million years ago. About 65 million years ago, the peninsula encountered a newly formed hot upward jet of molten mantle material known as the Réunion Hotspot, which is still erupting in its original location in the southwestern Indian Ocean in the form of volcanoes on the island of Réunion.   The stationary hot upward jet of the mantle melted the rigid outer layer of the Indian lithospheric plate and injected basaltic magma through its very ancient crust.  While the Indian plate kept plowing northward, some two to three billion cubic kilometres of this basaltic lava - extremely hot with the temperature of 1200°C and viscous liquid like jaggery or honey at room temperature -- crept over the region.  All previous vegetation and fauna lay completely charred and buried under these lava flows. 

Geologists and geophysicists have technologies to see through these thick basaltic rocks; they have conjectured pre-hotspot failed continental rifts (places where continents begin to separate but don’t quite make it into ocean basins) and could contain hard to reach petroleum and/or natural gas resources.  The Bombay High is one of the more accessible associated petroleum deposits formed on the western continental margin of India.