What is "mesoplates"

The concept of "mesoplates" was introduced as a heuristic for characterizing the motion of lithospheric plates relative to the sublithospheric source region of hotspot volcanism (Pilger, 2003). W. Jason Morgan (1972), originally suggested that hotspots (inferred by J. Tuzo Wilson) beneath such active volcanic regions as Hawaii and Iceland form a fixed "absolute" frame of reference for the motion of the overlying plates. However, the existence of a globally fixed reference frame for island- seamount chains and aseismic ridges ("traces") that are inferred to have originated from hotspots was quickly discounted by the primitive plate reconstructions available in the mid-1970s (Molnar and Atwater, 1973). Further, paleomagnetic measurements imply that hotspots have moved relative to the magnetic poles of the Earth (the magnetic poles are further inferred to correspond with the rotational poles of the planet when averaged over thousands of years). Aside: the term "hotspot" is used herein without any genetic implications. The term "melting spot" might well be more applicable.