伊通盆地横头山火山机构综合地球物理探测

Integrated Geophysical Exploration of Volcanic Edifice of Hengtoushan Volcano,Yitong Basin

火山隐伏机构的研究对火山演化、火山地热勘探与开发具有重要的意义。本文选取伊通盆地内的横头山火山开展研究,采用航磁、大地电磁测深、可控源音频大地电磁测深等多种地球物理方法探测火山隐伏机构,揭示了横头山火山的形成时间和深部动力学过程,以及隐伏岩体的空间形态和构造环境,确立了一套针对隐伏火山机构的地球物理探测体系。研究表明:横头山火山形成于第四纪早更新世晚期,在压扭应力作用下,玄武岩岩浆由深部沿马鞍山断裂挤出地表,现阶段岩浆通道已经闭合,一部分岩浆停留在通道中;横头山火山隐伏部分与围岩存在较大磁性差异,地表磁异常面积为2.6km2,沿马鞍山断裂北东向不均匀分布,埋藏深度小于1 000m。

The Yitong basin is a Cenozoic fault basin in the northern part of the Tan-Lu fault zone.The development and evolution of the Yitong basin is accompanied by strong volcanic activity.The distribution of buried volcanic edifices is of great significance to the study of volcanic evolution,geothermal exploration,and development in Yitong basin.In this study,we took the Hengtoushan volcano in the Yitong volcanic group as the research object,and used aeromagnetic measurements to determine the plane range of the buried volcanic edifice.The magnetic anomaly of the Hengtoushan volcanic area ranges of 2.6 km 2.Using an electromagnetic sounding(MT)section through the Hengtoushan volcanic area,we obtained the deep electrical structure,and analyzed the cause of the Hengtoushan volcano.The study shows that the volcanic strata formed in the first part of the Quaternary in Early Pleistocene,and under the action of torsional stress the basaltic magma crushed out of the surface along the Maanshan fault or stuck in the fault.Now,the magma channel is closed.Using the controllable source audio magneto telluric sounding method,the fine electrical structure near the Hengtoushan volcano was obtained to determine the shape and distribution range of the concealed magma capsule.Based on the above results,we obtained a clear understanding of the formation time,deep dynamic process,the spatial morphology,and the tectonic environment of the Hengtoushan volcano.We established a geophysical imaging mechanism for a buried volcanic edifice,which provides a reference for the development of volcanic geothermal systems in the Yitong basin.