Testing the occurrence of Late Jurassic true polar wander using the La Negra volcanics of northern Chile
Testing the occurrence of Late Jurassic true polar wander using the La Negra volcanics of northern Chile
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DOI：
10.1016/j.epsl.2019.115835
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发表时间：
2020-01-01
影响因子：
5.3
通讯作者：
Creveling, Jessica R.
中科院分区：
文献类型：
--
作者：
Fu, Roger R.;Kent, Dennis V.;Creveling, Jessica R.
真极漂移（TPW）是由地幔和地球表面质量重新分布驱动的壳幔系统的重新定向。在理想情况下，TPW 的表征需要对所有主要板块运动的古地磁约束以及相对板块位置的独立重建。虽然由于缺乏海洋板块而无法用于中生代前 TPW 推断，但它们可用于侏罗纪晚期（165-145 Ma）“怪物转变”，类似于 30 度振幅的 TPW 事件。在这里，我们对智利北部的 La Negra 火山进行了古地磁采样和 Ar-Ar 地质年代学，产生了两个新的古地磁极，年龄分别为 165.8 +/- 1.8 Ma（1 西格玛；84.3 度北纬 0.9 度东经；α(95) = 7.6 度；N = 28）和 152.8 +/- 0.8 Ma（84.5 度北纬 256.4 度） E 度； α(9)5 = 10.8 度； N = 18）。通过将这些数据与其他最近发表的结果相结合，我们计算出在 170 到 145 Ma 之间，岩石圈净旋转为 25.3 度 +/- 7.3 度（1 sigma），平均速率为 1.21 度 +/- 0.35 度 My(-1)，在 160 到 145 Ma 之间，峰值速率为 1.46 度 +/- 0.65 度 My(-1)。这些速率与太平洋板块的推论一致，意味着真正的整个岩石圈旋转。考虑到涉及整个岩石圈的相干运动，我们得出结论，地球在大约 165 到 145 Ma 之间经历了快速的 TPW，这可能是由北美西部边缘俯冲停止所驱动的。 (C) 2019 Elsevier B.V. 保留所有权利。
True polar wander (TPW) is the reorientation of the crust-mantle system driven by the redistribution of masses in the mantle and on the Earth's surface. In the ideal case, characterization of TPW requires paleomagnetic constraints on the motion of all major plates and independent reconstructions of relative plate positions. While such complete datasets are absent for pre-Mesozoic TPW inferences due to the absence of oceanic plates, they are available for the Late Jurassic (165-145 Ma) "monster shift", a similar to 30 degrees amplitude proposed TPW event. Here we perform paleomagnetic sampling and Ar-Ar geochronology on the La Negra volcanics of Northern Chile, producing two new paleomagnetic poles with ages 165.8 +/- 1.8 Ma (1 sigma; 84.3 degrees N 0.9 degrees E; alpha(95) = 7.6 degrees; N = 28) and 152.8 +/- 0.8 Ma (84.5 degrees N 256.4 degrees E; alpha(9)5 = 10.8 degrees; N = 18). By combining these data with other recently published results, we compute a net lithospheric rotation of 25.3 degrees +/- 7.3 degrees (1 sigma) at a mean rate of 1.21 degrees +/- 0.35 degrees My(-1) between 170 and 145 Ma with a peak rate of 1.46 degrees +/- 0.65 degrees My(-1) between 160 and 145 Ma. These rates are consistent with inferences from the Pacific Plate, implying true whole lithosphere rotation. Given coherent motion involving the entire lithosphere, we conclude that the Earth underwent rapid TPW between approximately 165 and 145 Ma, potentially driven by the cessation of subduction along the western North American margin. (C) 2019 Elsevier B.V. All rights reserved.