A 3-D conductivity model of the Australian continent using observatory and magnetometer array data
A 3-D conductivity model of the Australian continent using observatory and magnetometer array data
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DOI：
10.1093/gji/ggu188
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发表时间：
2014-08-01
影响因子：
2.8
通讯作者：
Fuji-ta, Kiyoshi
中科院分区：
文献类型：
--
作者：
Wang, Liejun;Hitchman, Adrian P.;Fuji-ta, Kiyoshi
本文提出了一个探索性的澳大利亚大陆电导率结构的三维模型。该模型是来自澳大利亚全阵列地磁站的垂直磁场传递函数的反演。地壳电导率异常明显的模型是一致的，与以前绘制的独立的磁强计阵列研究和新的电气结构的建议在上地幔。该模型代表了一个无缝的大陆尺度的基础上，进一步的模型可能来自后续的studies.The模型揭示了三个上地幔增强电导率异常下的东澳大利亚东部的西太平洋地区和两个上地幔异常下的西太平洋地区。其中两个异常已被最近的大地电磁（MT）调查，一个在Yilgarn Ekon-Officer Basin-Musgrave块，另一个在高勒Ekon-Officer区域，并与MT结果一致。在澳大利亚中部的大部分地区，在模型中观察到50-100公里深处的电导率增强。该区域与75-100公里处公认的地震速度梯度很好地对应。在西澳大利亚州，也观察到了西太平洋地区的电导率差异。皮尔巴拉火山在约100公里处表现为电导率增强异常，与面波层析成像模型中明显的低速异常对应良好。Yilgarn Einion被成像为低电导率体，电导率比Pilbara Einion低两个数量级，持续到更深的深度。
An exploratory 3-D model of the electrical conductivity structure of the Australian continent is presented. The model is derived from the inversion of vertical magnetic-field transfer functions from the Australia-wide Array of Geomagnetic Stations. Crustal conductivity anomalies evident in the model are consistent with those previously mapped by independent magnetometer array studies and new electrical structures are suggested in the upper mantle. The model represents a seamless continent-scale basis for further models likely to be derived from subsequent studies.The model reveals three upper-mantle enhanced-conductivity anomalies beneath Archaean cratonic regions and two upper-mantle anomalies beneath Phanerozoic terranes in eastern Australia. Two of these anomalies have been investigated by recent magnetotelluric (MT) surveys, one in the Yilgarn Craton-Officer Basin-Musgrave Block the other in the Gawler Craton region, and are consistent with the MT results. Across much of central Australia enhanced conductivity at depths of 50-100 km is observed in the model. This region corresponds well with a recognized seismic velocity gradient at 75-100 km. Conductivity differences are also observed beneath Archaean cratons in Western Australia. The Pilbara Craton is represented as an enhanced conductivity anomaly at about 100 km, corresponding well with the lower-velocity anomaly evident in surface wave tomography models. The Yilgarn Craton is imaged as a low-conductivity body, with conductivity two orders of magnitude lower than the Pilbara Craton, continuing to greater depths.