Analyze the structural evolution and petroleum geology of the Assam-Arakan Basin: Assertion (A): The Assam shelf contains prolific commercial hydrocarbon reservoirs trapped within Tertiary sandstone sequences such as the Tipam and Barail groups. Reason (R): The basin's tectonic history involving rapid sedimentation and subsequent folding against the Shillong plateau created ideal structural and stratigraphic traps for petroleum accumulation. Which of the following is correct?

💡 Solution & Explanation

The Assam-Arakan sedimentary basin is one of India's oldest and richest oil-producing regions, where Tertiary sandstone reservoirs like the Barail and Tipam formations sealed by thick shale layers trap significant petroleum reserves under favourable tectonic compression. Incorrect explanations would associate these hydrocarbon accumulations with metamorphic basement rocks or volcanic traps. Discovery of oil at Digboi in the late nineteenth century marked the inception of modern commercial petroleum extraction in South Asia.