What Is The Significance Of The Presence Of Pillow Lava In The Deccan Trap Basalts Of India, And How Does It Relate To The Theory Of A Marine Origin For These Rocks, In Contrast To The Prevailing View Of Their Continental Flood Basalt Origin?

The presence of pillow lava in the Deccan Traps of India is significant as it indicates that some of the volcanic activity occurred in an underwater environment, suggesting a marine influence during their formation. Pillow lava forms when lava cools rapidly upon contact with water, creating characteristic pillow-like structures. While the majority of the Deccan Traps are classified as continental flood basalts, the existence of pillow lava introduces a nuanced understanding of the geological history.

The Deccan Traps, formed around the Cretaceous-Paleogene boundary, are primarily associated with large-scale continental volcanism due to a mantle plume activity during the breakup of Gondwana. However, the presence of pillow lava suggests that initial phases may have occurred in a marine setting, possibly as the region transitioned from a marine to a continental environment. This implies a complex origin involving both continental and marine volcanism.

Geochemical similarities between pillow lavas and continental basalts suggest a shared magma source, while sedimentary evidence and fossils could further support marine influence. Despite this, the prevailing view remains that the Deccan Traps are predominantly continental flood basalts, with pillow lava indicating localized marine conditions rather than a complete reclassification.

In conclusion, the pillow lava highlights the multifaceted nature of the Deccan Traps' formation, incorporating both continental and marine environments, but does not overturn their classification as primarily continental flood basalts.