Superplumes or supercontinents?: Comment and Reply (Sheridan)

Anderson (1994) addressed a fundamental tectonic question: What is the role of "superplumes" in the pulses of Earth? Larson (1991a) attributed the mid-Cretaceous pulse to a superplume rising directly from the core-mantle boundary to create the Pacific large igneous provinces (LIPs). Anderson (1994) questioned this superplume explanation for magmatism, increased spreading rates, and other phenomena of the Cretaceous pulse; he interpreted these phenomena as being the result of episodic plate reorganizations. He pointed out that nonplume explanations are required for many LIPs. For example, preexisting lithospheric sutures localize mantle upwellings along rifted continental edges (Sheridan et al., 1993). Anderson (1994) stated that plate reorganizations allow magmas to passively intrude newly extended lithosphere from two long-lived upper-mantle hot domains, one under the Pacific and one under Pangea. He interpreted the mid-Cretaceous pulse of rapid expansion of the Pacific plate as genetically related to the breakup of Pangea.