Terrestrial Maria: The Origins of Large Basalt Plateaus, Hotspot Tracks and Spreading Ridges

Large lava plateaus, which form abruptly within plates without apparent tectonic cause, appear to be the terrestrial equivalents of lunar maria. Deep erosion of lava plateaus reveals that their magma chambers are gabbro and granophyre complexes, the classic lopoliths. The close association of the Deccan Plateau with the timing of the terminal Cretaceous boundary clay suggests that it is an impact crater large enough to cause pressure relief melting in the asthenosphere. Basalt then flooded the crater to form a lava lake, the terrestrial equivalent of a lunar mare. Part of the crater rim survives in the Amirante Ridge. The Carlsberg oceanic ridge and Chagos-Laccadive hotspot track formed simultaneously with the Deccan Plateau. Several other Mesozoic and Cenozoic lava plateaus are parts of similar arrays of simultaneous features. One of those is the southern Oregon part of the Columbia Plateau, with its associated continental rifting in the northern Basin and Range, and the Yellowstone hotspot track along t...