Lithospheric structure of Tasmania from a novel form of teleseismic tomography
Lithospheric structure of Tasmania from a novel form of teleseismic tomography
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DOI：
10.1029/2005jb003803
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发表时间：
2006-02
影响因子：
--
通讯作者：
N. Rawlinson;A. Reading;B. Kennett
中科院分区：
文献类型：
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作者：
N. Rawlinson;A. Reading;B. Kennett
2001年和2002年，在塔斯马尼亚岛（澳大利亚东南部）北方部署了72个地震记录仪的临时阵列，目的是利用三维地震层析成像技术对下伏地壳和上地幔进行成像。利用最近发展起来的自适应叠加技术，从101个5个月的远震记录中提取了6520个相对P波到时残差。一种新的迭代非线性层析过程的基础上的子空间反演方案和快速推进方法，基于网格的程函求解器，被用来映射的P波速度异常的剩余图案。新方案被证明是快速和鲁棒的，使其非常适合于大型数据集和复杂异常的重建。由此产生的塔斯马尼亚岛的断层图像表现出显着的横向扰动P波速度结构（5%）从1-D参考模型。一个显着的过渡，从较高的速度在东部到较低的速度在西部强烈支持的想法，塔斯马尼亚东部是由致密的岩石与海洋地壳的亲和力，与塔斯马尼亚西部的大陆衍生的硅质岩芯形成对比。值得注意的是，添马舰断裂系统并没有覆盖从相对快到慢的速度的狭窄过渡，这表明它可能是一个近地表的功能，而不是更深的地壳规模的表现，如以前所认为的。再往西，在Rocky Cape群和亚瑟线性构造下方的相对高速物质的东倾带可能与中寒武世Delamerian造山运动相关的海洋岩石圈的残余俯冲有关。
In 2001 and 2002, a temporary array of 72 seismic recorders was deployed across northern Tasmania (SE Australia), with the aim of imaging the underlying crust and upper mantle using three-dimensional (3-D) teleseismic tomography. Using a recently developed adaptive stacking technique, 6520 relative P wave arrival time residuals have been picked from 101 distant earthquake records spanning a 5 month period. A novel iterative nonlinear tomographic procedure based on a subspace inversion scheme and the fast marching method, a grid-based eikonal solver, is used to map the residual patterns as P wave velocity anomalies. The new scheme proves to be both fast and robust, making it well suited to large data sets and the reconstruction of complex anomalies. The resultant tomographic images of Tasmania exhibit significant lateral perturbations in P wave velocity structure (5%) from a 1-D reference model. A marked transition from higher velocities in the east to lower velocities in the west strongly supports the idea that eastern Tasmania is underlain by dense rocks with an oceanic crustal affinity, contrasting with the continentally derived siliciclastic core of western Tasmania. Significantly, the Tamar Fracture System does not overlie the narrow transition from relatively fast to slow velocities, which suggests that it may be a near-surface feature rather than a manifestation of deeper crustal-scale suturing as previously thought. Farther west, an easterly dipping zone of relatively high velocity material beneath the Rocky Cape Group and Arthur Lineament may be related to remnant subduction of oceanic lithosphere associated with the mid-Cambrian Delamerian Orogeny.