The Mongol-Okhotsk suture and the Adaatsag ophiolite belt are associated with the closure of the Mongol-Okhotsk paleo-ocean and are located within the Central Asian Orogenic Belt (CAOB) and Mongolia. The suture zone is flanked by volcanic-plutonic belts that host significant metallogenic zones, containing deposits of copper and gold. The tectonic evolution of this region is not fully understood and the lithospheric structure has been poorly studied. We analyze magnetotelluric data and generate a model of the electrical resistivity distribution across this region. Whereas the northern segment has a sharp transition from a high-resistivity upper crust to a low-resistivity lower crust, as observed beneath the Hangai Dome, the southern segment does not show this transition. A wide, low-resistivity zone (1–100 Ωm) imaged in the crust and lithospheric mantle is coincident with the Mongol-Okhotsk suture and ophiolite, revealing a clear and significant lithospheric-scale feature. Across the profile, numerous narrow, vertically oriented, low-resistivity features (1–100 Ωm) are spatially associated remarkably well with the proposed boundaries of tectonic domains. These results confirm ideas about the development of the CAOB. Some of these low-resistivity features are beneath the surface locations of large mineral zones, and likely represent fossil fluid pathways. We show congruent seismic velocity models for comparison and the results show a large-scale low-velocity anomaly (decrease of 2%–3%) that correlates with the location of the low-resistivity anomaly below the Mongol-Okhotsk suture. The geophysical results, combined with geological and geochemical data, provide insights into the structure of this region and help shed light on unanswered questions.

中文翻译：

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从电阻率成像和地震速度模型洞察蒙古-鄂霍茨克缝合带、阿达萨格蛇绿岩和中亚造山带（蒙古）的构造边界

蒙古-鄂霍茨克缝合带和阿达萨格蛇绿岩带与蒙古-鄂霍茨克古海洋的闭合有关，位于中亚造山带（CAOB）和蒙古境内。缝合带两侧是火山-深成带，其中有重要的成矿带，含有铜和金矿床。该地区的构造演化尚不完全清楚，岩石圈结构研究也很少。我们分析大地电磁数据并生成该区域电阻率分布的模型。正如在杭盖圆顶下方观察到的那样，北段有从高电阻率上地壳到低电阻率下地壳的急剧过渡，而南段则没有显示这种过渡。在地壳和岩石圈地幔中成像的宽阔低电阻率带（1-100 Ωm）与蒙古-鄂霍次克缝合带和蛇绿岩重合，揭示了清晰而显着的岩石圈尺度特征。在整个剖面上，许多狭窄的、垂直定向的、低电阻率特征（1-100 Ωm）在空间上与所提出的构造域边界有很好的关联。这些结果证实了关于 CAOB 发展的想法。其中一些低电阻率特征位于大型矿区的表面位置下方，可能代表化石流体通道。我们展示了一致的地震速度模型进行比较，结果显示了与蒙古-鄂霍次克缝合线下方低电阻率异常位置相关的大规模低速异常（下降 2%–3%）。地球物理结果与地质和地球化学数据相结合，提供了对该地区结构的深入了解，并有助于阐明尚未解答的问题。