Tracking the Australian plate motion through the Cenozoic: Constraints from 40Ar/39Ar geochronology
Tracking the Australian plate motion through the Cenozoic: Constraints from 40Ar/39Ar geochronology
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DOI：
10.1002/tect.20084
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发表时间：
2013-09
期刊：
影响因子：
4.2
通讯作者：
B. E. Cohen;K. Knesel;P. Vasconcelos;W. Schellart
中科院分区：
文献类型：
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作者：
B. E. Cohen;K. Knesel;P. Vasconcelos;W. Schellart
在这里，我们使用澳大利亚板内火山的地质年代学来构建一个高分辨率的板块速度记录，并探讨西南太平洋的构造事件如何影响板块运动。来自5座火山的9个样品的年龄为33.6 ± 0.5 ~ 27.3 ± 0.4 Ma，与已发表的30 ~ 16 Ma的年龄相结合，表明火山迁移的速率不是恒定的。相反，结果表明澳大利亚板块运动发生了明显变化。在34 ~ 30（±0.5）Ma和23 ~ 16（±0.5）Ma，向北的速度分别为61 ± 8和57 ± 4 km/Ma，在30 ~ 29（±0.5）Ma和26 ~ 23（±0.5）Ma，向北的速度明显减小到20 ± 10和22 ± 5 km/Ma。这些速度的降低是同时在新几内亚和翁东爪哇，分别与构造碰撞。在这些缓慢运动的周期之间，有一个短暂的29-26（±0.5）Ma的爆发，板块以100 ± 20 km/Ma的速度快速向北运动。我们评估了这种异常快速的速度的潜在机制，包括灾难性的板片穿透到下地幔，岩石圈的热机械侵蚀和羽推力;没有一个是合适的。然而，这段快速运动的时期与一个主要的向南传播的板块撕裂相吻合，该板块撕裂是在新喀里多尼亚俯冲和蛇绿岩仰冲的部分堵塞之后，沿着东北板块边缘沿着发展的。虽然目前还不清楚这样的事件是否可以在驱动快速板块运动中发挥作用，但数值或模拟模型可能有助于解决这个问题。
Here we use geochronology of Australian intraplate volcanoes to construct a high‐resolution plate‐velocity record and to explore how tectonic events in the southwest Pacific may have influenced plate motion. Nine samples from five volcanoes yield ages from 33.6 ± 0.5 to 27.3 ± 0.4 Ma and, when combined with published ages from 30 to 16 Ma, show that the rate of volcanic migration was not constant. Instead, the results indicate distinct changes in Australian plate motion. Fast northward velocities (61 ± 8 and 57 ± 4 km/Ma) prevailed from 34 to 30 (±0.5) and from 23 to 16 (±0.5) Ma, respectively, with distinct reductions to 20 ± 10 and 22 ± 5 km/Ma from 30 to 29 (±0.5) Ma and from 26 to 23 (±0.5) Ma. These velocity reductions are concurrent with tectonic collisions in New Guinea and Ontong Java, respectively. Interspersed between the periods of sluggish motion is a brief 29–26 (±0.5) Ma burst of atypically fast northward plate movement of 100 ± 20 km/Ma. We evaluate potential mechanisms for this atypically fast velocity, including catastrophic slab penetration into the lower mantle, thermomechanical erosion of the lithosphere, and plume‐push forces; none are appropriate. This period of fast motion was, however, coincident with a major southward propagating slab tear that developed along the northeastern plate margin, following partial jamming of subduction and ophiolite obduction in New Caledonia. Although it is unclear whether such an event can play a role in driving fast plate motion, numerical or analogue models may help address this question.