Challenges to Establishing a Global Paleolatitude Framework:
Paleomagnetic Inconsistencies in the Plate Circuit Through Antarctica
Abstract
The paleolatitude distribution of paleoclimate proxies and contintential
landmass is an important constraint for modeling and understanding
paleoclimate. True polar wander (TPW), which can produce large,
potentially rapid changes in paleolatitude, is a necessary component in
paleolatitude reconstructions. Prior workers, e.g., van Hinsbergen et
al. (2015), have created paleolatitude frameworks from global
continental apparent polar wander paths (APWPs) drawn from running means
of continental paleomagnetic studies (e.g., Torsvik et al. 2012). These
are limited by the precision of the running mean, poor age resolution
amplified by use of a running mean, and the uncertainties and the
unknowns of ancient plate motion circuits. In particular, the Pacific
Plate is linked to the global plate circuit through Antarctica. Early
paleomagnetic tests of this circuit (Suarez & Molnar, 1980; Gordon &
Cox 1980; Acton & Gordon 1994) indicated inconsistency of the circuit
with paleomagnetic data such that the reconstructed Pacific plate did
not move as far north as indicated by its indigenous paleomagnetic data.
Some later work has asserted, however, that updated paleomagnetic data
and plate reconstructions no longer indicate the inconsistency found
before (Doubrovine & Tarduno 2008). Important progress has also been
made in estimating the motion between East and West Antarctica from
seafloor data (e.g. Granot & Dyment 2018). We revisit these questions
here. We test the predictions of the global paleolatitude framework at
points across the Pacific Plate using a well-constrained observed APWP
constructed from indigenous Pacific plate data from skewness analysis of
marine magnetic anomalies (Schouten & Cande 1976; Cox & Gordon 1980)
and locations of paleo-equatorial sediments (Moore et al. 2004;
Woodworth & Gordon 2018), which uniquely determine Pacific Plate
paleolatitude independent of plate circuits. The misfit between the
observed and predicted paleolatitude varies with longitude across the
plate and is as large as ~10±3°, with the largest misfit
occurring between 40 and 60 Ma. Implications of this discrepancy will be
discussed and an improved paleolatitude framework for the Pacific plate
will be presented.