Skewness analysis of Pacific Plate Magnetic Anomalies 22r-22n-21r and possible implications for the formation of the Hawaiian-Emperor Bend, True Polar Wander, and Cenozoic Global Climate change
Abstract
The time interval from 50 Ma to 47 Ma, is a critical one in the evolution of the Pacific plate, Pacific hotspots (Morgan, 1972; Raymond et al. 2000; Tarduno et al. 2003), and Cenozoic global climate. Moreover, the interval overlaps, but slightly lags, the Early Eocene Climate Optimum (51-53 Ma), and thus coincides with the transition from Greenhouse to Icehouse Earth (Zachos et al., 2001).
Recent work at Rice University has shown that the position of the spin axis was 3 degrees away from its present position from 48 to 12 Ma, and 11 degrees away from 80 Ma to 55 Ma, indicating an episode of true polar wander with a displacement of the solid Earth relative to the spin axis of 8° between 55 and 48 Ma. Schouten & Cande (1976) proposed a method for determining a paleomagnetic pole by analyzing the skewness of marine magnetic anomalies: the phase parameter called Theta (θ), measured for every anomaly profile belonging to different sets of contemporaneous magnetic anomalies (e.g. sets the Pacific Basin), defines semi-great circles intersecting to the paleopole. Gordon & Cox (1980) proposed a least-squares method of combining together the values of effective remanent inclination implied by the values of skewness to estimate paleomagnetic poles and confidence limits. These approaches have been used to determine Pacific plate pole positions for neighboring Chrons 32n (72 Ma), 31n-27r ( 66 Ma), 26r (60 Ma) , 25r (57 Ma), 24r (55 Ma), 20r (45 Ma), and 12r (32 Ma) (respectively, Petronotis & Gordon, 1999 [see also Koivisto et al., 2011]; Acton & Gordon, 1991; Seidman et al., (in prep); Petronotis et al. 1994, Zheng et al., 2018; Woodworth & Gordon, this meeting, Horner-Johnson & Gordon, 2010). Therefore, here we present an analysis of the skewness of the anomaly sequence 22r to 21r (50.6 Ma to 47.3 Ma) recording seafloor spreading between the Pacific and Farallon plates in the Pacific plate spreading corridors between the Murray Fracture Zone and Easter Fracture Zone. Our aims are to determine a new paleomagnetic pole with compact confidence limits for this time interval, and to narrow the timing of this jump in location in this two positions. Finally, we combine our results with prior results to obtain the implications for true polar wander and its relation to Pacific basin tectonics and Cenozoic global climate change.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMGP31A0710S
- Keywords:
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- 1229 Reference systems;
- GEODESY AND GRAVITYDE: 1525 Paleomagnetism applied to tectonics: regional;
- global;
- GEOMAGNETISM AND PALEOMAGNETISMDE: 8137 Hotspots;
- large igneous provinces;
- and flood basalt volcanism;
- TECTONOPHYSICSDE: 8158 Plate motions: present and recent;
- TECTONOPHYSICS