Jackson’s episode

The changes in stress fields, and intensities of igneous and hydrothermal activities seem to correlate to oscillatory motion of the Pacific plate (Jackson s episodes) (Jackson et al., 1975 Jackson and Shaw, 1975) (Masuda, 1984). Masuda (1984) and Takeuchi (1987) pointed out that the oscillatory motion of Pacific plate during the least 42 Ma correlates with magmatism, the intensity of tectonism, the change of stress field and the history of sedimentary basin in arc-trench system (Fig. 1.147). The above arguments also suggest that the mineralizations in arc and back-arc systems relate to the oscillatory motion of the Pacific plate. 

This metallogenic epoch in and near the Japanese Islands correlates well with Jackson s episode (Masuda, 1984). Jackson s episode means the change in the direction of Pacific plate, which was estimated from the array and age of Hawaiian islands by Jackson etal. (1975) (Fig. 4.8). 

It is suggested that the mode of subduction of the Pacific Plate since the middle Miocene age related to Jackson s episode, hence oscillation of direction of lateral movement of Pacific plate. Synchronized igneous and hydrothermal activities and Jackson s episode indicate that the formations and characteristics of hydrothermal ore deposits (Kuroko and epithermal vein-type deposits) are largely influenced by plate tectonics (mode of subduction, direction of plate movement, etc.). For example, sulfur isotopic composition of sulfides is not controlled by /o and pH, but by of... 

Figure 1.147. Jackson s curve and arc stress reorientations. Apparent swing motion of Pacific Plate (Jackson et al., 1975) and regional stress orientation at the Northeast Honshu convergent margin are illustrated in order to show their synchronous relationship. Dashed line represents the average trend of the Hawaiian volcanic chain. Pacific plate moves along the direction with fluctuation in reference to Hawaii Hot Spot. Vertically shaded parts of the graph indicate the climax phases of clockwise episodes . Lower part of the figure shows the phases and reversals in orientation of tectonic stress fields on the inner zone of Northeast Honshu Arc (Takeuchi, 1987).

McGorry, P. D., Yung, A. R., Phillips, L. J., Yuen, H. P., Francey, S., Cosgrave, E. M., Germano, D., Bravin, J., McDonald, T., Blair, A., Adlard, S., Jackson, H. 2002, Randomized controlled trial of interventions designed to reduce the risk of progression to first-episode psychosis in a clinical sample with subthreshold symptoms, Arch.Gen.Psychiatry, vol. 59, no. 10, pp. 921-928. 

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