Arterial System of Lava Tubes and Channels within Deccan Volcanics of Western India

Interpretation of remotely sensed and field data has brought out an integrated arterial system comprising lava tubes and channels, through which molten basaltic lava seems to have flowed to long distances in thc Deccan Trap of western Maharashtra and southern Madhya Pradesh. Remnants of lava tubes and channels are identified at morc than two hundred places in the study arca, covering 120,000 km². The lava tubes and channcls are demarcated by their unique sinuous shapes and positive rclicf based on remotely sensed data. In the field, they are recognized by their tubular outline, which is invariably composed of reddened fragmentary volcanic material, encasing dark greyish basalt having uniquc textures. The diameter of lava tubcs and width of clianncls arc much larger within the study area than those reported from the Quaternary and Recent volcanics in different parts of the world which suggests very high effusive rates during Deccan volcanism. Mostly these tubular structures are filled by solidified lava suggesting that flow gradients were very low and therefore withdrawal of' molten lavas has not taken place. Mostly they are confined to the compound flow secluences and are rarely seen within the simple flows. These remnants are predominantly exposed between 200 m and 800 m elevations and arc locatcd at higher elevations in thc western part of the study area and at successively lower levels in the easterly direction. This indicates that block faulting controlled by en echelon basement faults, was largely resportsible for down faulting of successive blocks in the easterly direction.