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Paleomagnetic evidence for tertiary anticlockwise rotation in southwest Puerto Rico
Author(s) -
Van Fossen Mickey C.,
Channell James E. T.,
Schellekens Johannes H.
Publication year - 1989
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl016i008p00819
Subject(s) - clockwise , paleomagnetism , geology , cretaceous , paleontology , magnetization , rotation (mathematics) , seismology , magnetic declination , paleogene , geodesy , geometry , earth's magnetic field , physics , magnetic field , mathematics , quantum mechanics
Late Cretaceous and Eocene paleomagnetic results from calcareous mudstone, limestone, and volcaniclastic rocks in southwest Puerto Rico yield a significant anticlockwise discordance in magnetization direction relative to North American reference data. Progressive thermal demagnetization has revealed stable, characteristic high blocking temperature magnetization components that display an intrasite bipolarity. The direction of this stable magnetization in tilt‐corrected coordinates is consistently either northwest and down, or southeast and up. The pole position (39.4° N.Lat.; 209.6° E.Long.; dp = 9.3°; dm = 16.7°; N = 10) suggests post Eocene anticlockwise rotation of the sampling region relative to North America by 45° about a vertical axis. A rotating block domain model in which north‐south compression is superimposed on WNW‐ESE strike‐slip faults in SW Puerto Rico can explain the inferred rotation.