Steps in lithospheric thickness within eastern Australia, evidence from surface wave tomography
Steps in lithospheric thickness within eastern Australia, evidence from surface wave tomography
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DOI：
10.1029/2007tc002116
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发表时间：
2008-08-01
期刊：
影响因子：
4.2
通讯作者：
Yoshizawa, K.
中科院分区：
文献类型：
--
作者：
Fishwick, S.;Heintz, M.;Yoshizawa, K.
通过最新的地震面波层析模型和横波速度水平梯度的计算，揭示了澳大利亚东部岩石圈厚度的一系列阶跃。新的图像包含了最近塔斯马尔实验的数据，提高了澳大利亚大陆的分辨率。通过与地表地质学和地球化学研究的对比，可以推断岩石圈厚度的阶梯与不同年龄的地块之间的边界有关。最西端的界线标志着大陆太古代至早元古代核心区的边缘。在东澳大利亚中部观察到了第二个岩石圈边界。在这条线以西，地球化学证据表明存在元古界岩石圈地幔，因此，这一界线可能代表了元古界向显生宙基底的转变。大陆东缘的构造以慢速度为主，表明该地区的大陆岩石圈很薄。慢波速度与最高地形和最近火山活动的位置之间有很强的相关性。在大陆边缘内陆，观察到地震波速度的强梯度带，表明岩石圈结构具有明显的阶跃。如果岩石圈厚度的阶跃在火山活动之前就已经到位，它可能起到了边界的作用，火山活动主要发生在较薄的岩石圈以东的下方。
A series of steps in the lithospheric thickness of eastern Australia are revealed by the latest seismic surface wave tomographic model and calculations of the horizontal gradient of shear wave speed. The new images incorporate data from the recent Tasmal experiment, improving resolution in continental Australia. Through comparisons with surface geology and geochemical studies, it is possible to infer that the steps in lithospheric thickness are related to boundaries between blocks of different age. The westernmost boundary marks the edge of the Archaean to Early-Proterozoic core of the continent. A second lithospheric boundary is observed in the central part of east Australia. To the west of this line, geochemical evidence suggests that there is Proterozoic lithospheric mantle, and this boundary may therefore represent the change from Proterozoic to Phanerozoic basement. The structure on the eastern margin of the continent is dominated by slow velocities, suggesting that in this area the continental lithosphere is very thin. There is a strong correlation between the slow wave speeds and the location of both the highest topography and recent volcanic activity. Inland of the continental margin, a zone of strong gradients in the seismic wave speed is observed, indicating a distinct step in lithospheric structure. If the step in lithospheric thickness was in place prior to volcanism, it may have acted as a boundary, with volcanism mainly occurring beneath the thinner lithosphere to the east.