Paleolatitude of the Southern Kerguelen Plateau Inferred from the Paleomagnetic Study of Late Cretaceous Basalts

Abstract

Paleomagnetic measurements were performed on 106 basalt samples collected from Holes 747C, 748C, 749C, and 750B. Basalt samples were recovered from the southern portion of the Kerguelen Plateau and the transitional zone between the northern and southern plateau in the south central Indian Ocean. The ages of basalts range from 100 to 115 Ma. In addition to the preliminary shipboard measurements (Schlich, Wise, et al., 1989), characteristic inclinations of the magnetization were obtained using mainly stepwise thermal demagnetization of the samples. Reliable paleomagnetic results were obtained from three sites (Sites 747, 748, and 749). The paleomagnetic inclinations of Sites 747, 748, and 749 are -51°, -63°, and -62°, respectively. The considerable differences between the paleomagnetic and present inclinations of about 70° at Sites 747, 748, and 749 indicate that displacement in the direction of the geomagnetic meridian has taken place since formation of the basalt. Shallower paleomagnetic inclinations than the present inclinations at each site imply a southward movement of the sites with respect to the geomagnetic pole. By comparing the apparent polar wander path of Antarctica with the virtual geomagnetic pole (VGP) of the Southern Kerguelen Plateau, we have concluded that no major tectonic movement has taken place between the Kerguelen Plateau and Antarctica since formation of the basalt (i.e., 100-115 Ma). The angular dispersion of the VGP for the Kerguelen Plateau is calculated as 17°.

Paleolatitudes of the Kerguelen hotspot: new paleomagnetic results and dynamic modeling

“…This result is supported by one lava £ow of similar age at Site 748 which yields a paleolatitude of 44.5 ‡S. The paleomagnetic samples from the two £ows at Site 750 had unstable magnetizations and no paleolatitude was determined [20].…”

“…The mean inclination from 13 lava £ows of Site 747 is 351 ‡ which is 11 ‡ shallower than the inclinations at Sites 748 and 749 [20]. This shallow inclination is most likely due to northward tilting of the basement at Site 747.…”

Geodynamic implications of moving Indian Ocean hotspots

“…[27^29]). The major problem for the Kerguelen plume source theory is that plate reconstruction models based on a ¢xed hotspot reference frame [28] [3,15,17,38,42,55,70].…”

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“…Solid squares for Suiko and Detroit Seamounts indicate total number of flow units, including volcaniclastic units. Kerguelen-Ninetyeast Ridge data from ODP Legs 120 (Inokuchi and Heider, 1992), 121 (Klootwijk et al, 1991), and 183 (Antretter et al, 2002). Pacific atolls/guyots data from ODP Legs 143 (Tarduno and Sager, 1995) and 144 (Nakanishi and Gee, 1995).…”