TY - JOUR
T1 - Large Rotation of the Easter Microplate as Evidenced by Oriented Paleomagnetic Samples from the Ocean Floor
AU - Cogné, J. P.
AU - Francheteau, J.
AU - Courtillot, V.
AU - Naar, D. F.
PY - 1995/1/1
Y1 - 1995/1/1
N2 - One of the goals of the Pito93 cruise along the perimeter of the Easter microplate was to obtain oriented rock samples from the ocean floor for paleomagnetic study. Using a new orienting device, the Geocompass, 14 oriented blocks were obtained during 6 dives conducted using the Ifremer DSRV Nautile . Paleomagnetic analysis shows that 13 of these 14 blocks give consistent results in thermal and AF demagnetizations, and reveals a mean Characteristic Remanent Magnetization (ChRM) direction within each block, with both normal and reverse polarities. After elimination of data from 5 blocks situated outside the microplate, and one block which bears an anomalous direction, we have computed a mean ChRM direction at Dm = 49.0°, Im = −39.0° (k = 10.2, α95 = 19.8 °, n = 7). Although the mean inclination is in agreement with the inclination of the recent dipole magnetic field (D = 0°, I = −43°), the average declination is significantly different from this direction, which we interpret as due to a bulk clockwise rotation of 48.5° ± 11° (after the bivariate average) of the Easter microplate over the past 2–3 Ma. This value is in excellent agreement with previous estimates based on remote geophysical measurements and models.
AB - One of the goals of the Pito93 cruise along the perimeter of the Easter microplate was to obtain oriented rock samples from the ocean floor for paleomagnetic study. Using a new orienting device, the Geocompass, 14 oriented blocks were obtained during 6 dives conducted using the Ifremer DSRV Nautile . Paleomagnetic analysis shows that 13 of these 14 blocks give consistent results in thermal and AF demagnetizations, and reveals a mean Characteristic Remanent Magnetization (ChRM) direction within each block, with both normal and reverse polarities. After elimination of data from 5 blocks situated outside the microplate, and one block which bears an anomalous direction, we have computed a mean ChRM direction at Dm = 49.0°, Im = −39.0° (k = 10.2, α95 = 19.8 °, n = 7). Although the mean inclination is in agreement with the inclination of the recent dipole magnetic field (D = 0°, I = −43°), the average declination is significantly different from this direction, which we interpret as due to a bulk clockwise rotation of 48.5° ± 11° (after the bivariate average) of the Easter microplate over the past 2–3 Ma. This value is in excellent agreement with previous estimates based on remote geophysical measurements and models.
UR - https://digitalcommons.usf.edu/msc_facpub/2235
UR - https://doi.org/10.1016/0012-821X(95)00191-E
U2 - 10.1016/0012-821X(95)00191-E
DO - 10.1016/0012-821X(95)00191-E
M3 - Article
VL - 136
JO - Earth and Planetary Science Letters
JF - Earth and Planetary Science Letters
ER -