Three-dimensional electromagnetic modeling of the Trans-European Suture Zone (EMTESZ 3-D)

在EMTESZ项目(跨欧洲缝合区的电磁研究)期间，实现了横跨德国东北部和波兰盆地的几个大地电磁(MT)横断面。它们是以二维(2-D)方式解释的，对于研究区东北德国-S瑞典部分的大多数数据来说，这当然是合理的。然而，在波兰盆地的中部，存在着一个明确的三维性指示，主要来自感应矢量：长期的真实矢量主要垂直于剖面。因此，二维模拟只能被视为解释的第一步，它甚至可能产生深部电导率结构的虚假图像。与此同时，3D反转代码变得更容易访问，计算性能(考虑内存和执行时间)现在允许更逼真的模型几何图形。因此，这项建议的一个目标是将这种--可自由获得的--代码应用于数据集，特别是查普莱克区块和盐丘的反转盆地地区。我们希望对盆地中的高导电性带--解释为明矾页岩层--有更清晰的认识，特别是对地幔最上层的良导体有更清晰的认识。3-D电导研究将补充这一方法。3-D反演将主要由我们的波兰项目合作伙伴在我们方面的密切互动/指导下进行，并与俄罗斯合作伙伴合作，后者将提供整个研究区域的电导图。关键词：跨欧缝合区、电磁学、三维电导率模型、三维反演

During the EMTESZ project (Electromagnetic Study of the Trans-European Suture Zone) several magnetotelluric (MT) transects across the Northeast German and the Polish Basin were realized. They were interpreted in a two-dimensional (2-D) manner, and this is certainly justified for most of the data in the NE German – S Swedish part of the study area. In the central part of the Polish Basin, however, a clear indication for three-dimensionality, mainly from induction vectors exists: real vectors at long periods point predominantly perpendicular to the profiles. Thus 2-D modeling can only be regarded as a first step in interpretation, which may even yield a false image of conductivity structures at depth. In the meanwhile, 3-D inversion codes have become more accessible and computing performance (considering memory and execution time) allows now for more realistic model geometries. It is thus an objective of this proposal to apply such – freely available – codes to the data set, particularly to the inverted basin area of the Czaplinek block and salt dome. We expect to get a clearer image of the highly conductive zone – interpreted as an alum shale layer – in the basin, and particularly of the good conductor in the uppermost mantle. 3-D conductance studies will complement this approach. The 3-D inversion will principally be carried out by our Polish project partners with close interaction/guidance from our side and in cooperation with the Russian partners, who will supply the conductance maps of the entire study area. Keywords: Trans-European Suture Zone, electromagnetics, 3-D conductivity models, 3-D inversion