Bounds on geologically current rates of motion of groups of hot spots

Abstract

It is widely believed that groups of hot spots in different regions of the world are in relative motion at rates of 10 to 30 mm a−1 or more. Here we present a new method for analyzing geologically current motion between groups of hot spots beneath different plates. In an inversion of 56 globally distributed, equally weighted trends of hot spot tracks, the dispersion is dominated by differences in trend between different plates rather than differences within plates. Nonetheless the rate of hot spot motion perpendicular to the direction of absolute plate motion, vperp, differs significantly from zero for only 3 of 10 plates and then by merely 0.3 to 1.4 mm a−1. The global mean upper bound on |vperp| is 3.2 ± 2.7 mm a−1. Therefore, hot spots move slowly and can be used to define a global reference frame for plate motions.

Uncertainties in Trends of Young Hot Spot Tracks

“…Wang et al (2017) equally weighted all trends and thus did not consider the question of what are the most appropriate uncertainties to assign to hot spot trends. For the case in which it is assumed that errors between different hot spot tracks are uncorrelated, Wang et al (2017) found a global 1σ standard deviation, σ gl , of 23.1°. For the case in which it is assumed that errors between different hot spot tracks are uncorrelated, Wang et al (2017) found a global 1σ standard deviation, σ gl , of 23.1°.…”

“…He postulated that plumes of hot rock rise up from deep in the mantle. Except for the work of Wang et al (2017), these prior studies have not resolved significant motion between hot spots. He used hot spot tracks, that is, chains of ancient volcanos leading to an active volcano, to estimate the geologically current motion of the plates relative to the deep mantle (Morgan, 1971).…”

“…Morgan (1971Morgan ( , 1972 proposed a framework for understanding mantle convection, hot spots, and the origin of volcanic island chains in the interior of plates and of excessive volcanism along plate boundaries. Since his work, hot spot tracks have been widely used to estimate plate motion relative to the deep mantle, especially for geologically current plate motions (e.g., Minster et al, 1974;Chase, 1978;Minster & Jordan, 1978;Gripp & Gordon, 1990Morgan & Morgan, 2007;Wang et al, 2017Wang et al, , 2018. He further suggested that the hot spots proposed by Wilson (1963) to explain chains of seamounts and islands, such as the Hawaiian island chain, are the surface manifestation of these plumes.…”

“…These problems include, but are not limited to, the estimation of velocities (and associated uncertainties) of the migration of trenches (Faccenna et al, 2007;Schellart et al, 2008), resolving the motion of ultraslow-moving plates such as Eurasia and Antarctica (Zheng et al, 2014), resolving motion between groups of hot spots (Wang et al, 2017), resolving motion of hot spots relative to the spin axis (e.g., Morgan, 1981;Gordon & Cape, 1981;Besse & Courtillot, 1991;Petronotis et al, 1994;Tarduno & Cottrell, 1997;Torsvik et al, 2002;Zheng et al, 2018), and unraveling the origins of upper mantle anisotropy (e.g., Becker et al, 2014;Beghein et al, 2014Beghein et al, , 2018Semple & Lenardic, 2018;VanderBeek & Toomey, 2017;Zheng et al, 2014). These problems include, but are not limited to, the estimation of velocities (and associated uncertainties) of the migration of trenches (Faccenna et al, 2007;Schellart et al, 2008), resolving the motion of ultraslow-moving plates such as Eurasia and Antarctica (Zheng et al, 2014), resolving motion between groups of hot spots (Wang et al, 2017), resolving motion of hot spots relative to the spin axis (e.g., Morgan, 1981;Gordon & Cape, 1981;Besse & Courtillot, 1991;Petronotis et al, 1994;Tarduno & Cottrell, 1997;Torsvik et al, 2002;Zheng et al, 2018), and unraveling the origins of upper mantle anisotropy (e.g., Becker et al, 2014;Beghein et al, 2014Beghein et al, , 2018Semple & Lenardic, 2018;VanderBeek & Toomey, 2017;Zheng et...…”

A Geologist Reflects on a Long Career

“…The time dependence of mantle convection has also become clear. Richard Gordon and his colleagues (Wang et al 2017) have shown that the circulation is surprisingly steady, though major changes do occur from time to time when the lower boundary Gravity from DIR-R5 (wavelengths shorter than the 500 km removed) Gravity field for Africa from DIR-R5 filtered as in Figure 5c, whose boundary is shown by the black and yellow box. layer becomes unstable.…”