Pacific Plate Apparent Polar Wander, Hot Spot Fixity, and True Polar Wander During the Formation of the Hawaiian Island and Seamount Chain From an Analysis of the Skewness of Magnetic Anomaly 20r (44 Ma)
Pacific Plate Apparent Polar Wander, Hot Spot Fixity, and True Polar Wander During the Formation of the Hawaiian Island and Seamount Chain From an Analysis of the Skewness of Magnetic Anomaly 20r (44 Ma)
复制标题
从磁异常 20r (44 Ma) 的偏斜度分析，夏威夷岛和海山链形成过程中的太平洋板块表观极地漂移、热点固定性和真实极地漂移
作者：
Lin Zheng;R. Gordon;D. Woodworth
虽然有充分的文件证明，自一些帝王海山形成以来，夏威夷热点相对于自旋轴向南移动，但对夏威夷岛链形成期间热点的古纬度知之甚少。为了更好地确定后者，在这里，我们通过调查太平洋板块上Murray和Marquesas断裂带之间的14架飞机和19艘船上磁异常20 r的偏斜度（不对称性）来估计44 Ma太平洋板块古磁极的位置。新的44 Ma古磁极（78.0°N，26.0°E，在101°处A95_1 = 5.4°，A95_2 = 2.0°）与太平洋热点相对于自旋轴固定的情况下所预期的位置相差0.4 °。这一转变是独立记录的年代12 r（32马）太平洋板块偏古磁极，也证实了古磁极重建的大陆，表明全球热点一致移动相对于自旋轴，可能是由于真正的极漂移，这可能会继续今天记录的光学天文学和大地甚长基线干涉。对磁性剖面记录的扩张速率的分析表明，扩张速率在2050 ~ 2042 Ma之间翻了一番（证实了先前的结果），正如预期的那样，如果夏威夷-皇帝链的弯曲记录了太平洋板块相对于深部地幔运动的变化。
While it is well documented that the Hawaiian hot spot has shifted southward relative to the spin axis since the formation of some of the Emperor seamounts, the paleolatitude of the hot spot during the formation of the Hawaiian chain is poorly known. To better determine the latter, here we estimate the location of the 44 Ma Pacific plate paleomagnetic pole by investigating the skewness (asymmetry) of 14 airplane and 19 ship‐board crossings of magnetic anomaly 20r between the Murray and Marquesas fracture zones on the Pacific plate. The new 44 Ma paleomagnetic pole (78.0°N, 26.0°E, A95_1 = 5.4° at 101°, A95_2 = 2.0°) differs by ≈4° from its position expected if the Pacific hot spots have been fixed relative to the spin axis. This shift is independently recorded by the chron 12r (32 Ma) Pacific plate skewness paleomagnetic pole and is also confirmed by paleomagnetic poles reconstructed from the continents, indicating that global hot spots have moved in unison with respect to the spin axis, probably due to true polar wander, which may continue today as recorded by optical astronomy and geodetic very long baseline interferometry. An analysis of spreading rates recorded in the magnetic profiles indicates that spreading rates doubled between ≈50 and ≈42 Ma (confirming prior results), as expected if the bend in the Hawaiian‐Emperor chain records a change in Pacific plate motion relative to the deep mantle.