基于地球物理电性特征的踏卡穹隆构造研究

    Structural Research of Taka Dome Based on Geophysical Electrical Characteristics

    • 摘要: 这是一篇地球科学领域的论文。踏卡穹隆与江浪穹隆位于松潘—甘孜地块南缘,地质特征显示其物质组成、变质-变形特征较为相似。江浪穹隆发现有里伍、黑牛洞、中咀等铜锌矿床,但踏卡穹隆同层位还未发现相似矿床。为查明踏卡穹隆中深部构造特征及成矿的关系,本次开展了不同时代地层的地球物理电性参数测定和音频大地电磁测深剖面,以获得地下中、深部电性特征。结果表明,穹隆总体显示为两侧低、中阻,核部高阻为主夹杂低阻的特征,整体电性特征与穹隆结构的时空规律相吻合。深部电性剖面中出现3条主要低阻异常带,推断为低阻岩性、断层或构造破碎带的反映;3条主要高阻异常带,推断为踏卡穹隆内完整的中、高阻特征的中元古界里伍群上段(Pt2l3)岩体反映。上述认识为探索踏卡穹隆中、深部地质空间结构提供了地球物理学上的证据。

       

      Abstract: This is an article in the field of earth sciences. Taka dome and Jianglang dome are located in the southern margin of Songpan-Ganzi block, and their geological characteristics indicate similar composition and metamorphic-deformation characteristics. Liwu, Heiniudong and Zhongsui deposits have been found in Jianglang Dome, while no similar deposits have been found in the same horizon of Taka Dome. To investigate the medium-deep part structure characteristics and mineralization of the Taka Dome, the geophysical electrical parameters and audio magnetotelluric sounding profiles of different strata of different ages were measured to obtain the electrical characteristics of the middle and deep subsurface. The results show that the overall characteristics of the dome are low and medium resistance on both sides, and high resistance in the core is mainly mixed with low resistance. The overall electrical characteristics are consistent with the spatiotemporal law of the dome structure. There are three main low-resistivity anomaly zones in the deep electrical profile, which are inferred to reflect the low-resistivity lithology, fault or structural fracture zone. The three main high-resistivity anomaly belts are inferred to be reflected by the upper member of the Mesoproterozoic Liwu Group (Pt2l3) with complete medium-high resistivity characteristics in the Taka dome. The above understanding provides geophysical evidence for exploring the medium-deep geological spatial structure of the Taka Dome.

       

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