Abstract

Based on Hawaiian hot spot analysis that used sediment rates and paleomagnetic skewness data, Woodworth and Gordon (2018) determined that the North geographic pole (then at 87°N, 164°E) was at a standstill from 48 Ma to 12 Ma. In the more recent time, since 12 Ma, Woodworth and Gordon indicate an episode of TPW of ~ 3° from our present pole location with southward movement of the tropical Pacific plate and northward movement of Greenland. The observed TPW of ~3° since 12 Ma could be associated with polar mass imbalance by episodic ice age glaciers, unknown internal mass movements below the thin crust, or a known and static mass imbalance caused by the massive Zanclean flood (ZF) filling the desiccated Mediterranean basin 5.33 Ma. The empty basin, max ~5 km below sea level now, contains 3.8 million km 3 (4*10 19 kg) of water and has a moment arm of ~ 5220 km from the earth's spin axis. For comparison, the last glacial maximum in the Scandinavian ice mass had about 6 million km 3 but with a much shorter lifetime and moment arm of 3,650 km. The Zanclean flood rapid addition (~2-year) of a large asymmetric mass onto the thin lithospheric shell likely helped drive the 3° TPW in the same direction as the Hawaii TPW data indicates, causing northward movement of Greenland and southward movement of the Pacific plate. Two analytical and two numerical models all indicate about a ~3º wobble shift in the lithosphere based on assumptions. Global sea level was reduced by ~0.1m. The rapid mass addition then caused an increased Earth lithosphere spin wobble (+/-3°) and nutation (Prograde period of 1.01 year) direct to the shell lithosphere with respect to the fixed bulk earth spin axis. As the wobble damping occurred in the low-friction region below the crust, it shifted the thin lithosphere direction ~180° over the North Pole from ~20° E Mediterranean region northward and at ~160° W Hawaii region southward in alignment to bulk Earth's fixed spin axis to lower crust mass imbalance as observed. This action is referred to as Rotational Alignment Motor (RAM) and derives its energy from the earth's vast rotational kinetic energy. The RAM spin mass balance stabilizer better explains the wandering part of TPW and functions as an elegant and simple mechanical analogy to spin balance surface mass changes while keeping them quite decoupled from the interior. Continental Drift (CD) and TPW are found to complement each other and work together. The CD Motor mechanism involves massive mantle convection currents that slowly and continually move the continents (cm/year) while TPW uses simple physics Wobble motion and the RAM drive to gracefully move the thin crust wobble imbalance relatively quickly (1m/yr small too much faster) to realign the crust for spin balance with the fixed mantle and core. Polar Drift (TPW) >1° is very infrequent with recent standstills of 50Ma before the Zanclean flood while CD always marches forward. During Ice Ages with large mass imbalances, TPW is likely very important. 12/29/2022 AGU Fall Meeting GP45B-0300 12/15/2022 Poster, Henry Voss, (NSL) 1