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Imaging the shallow crustal velocity structure of the Qingchengzi ore field on the Liaodong Peninsula, China, with a short-period dense array using ambient noise tomography
Tectonophysics ( IF 2.7 ) Pub Date : 2021-05-12 , DOI: 10.1016/j.tecto.2021.228913
Tongtong Xie , Tao Xu , Yinshuang Ai , Qingdong Zeng , Wei Zhang , Fan Zheng

The Qingchengzi ore field, which is located in the middle of the Liaodong Peninsula, has a large number of Au, Ag, and Pb-Zn deposits owing to Mesozoic tectonic and magmatic-hydrothermal activities. To reveal the relationship between shallow crustal velocity and gold mineralization and provide constraints on deep ore prospecting (> 1.5 km), ambient noise tomography consisting of an experimental short-period dense array with 334 seismographs surrounding the study region, is adopted. Shallow crustal velocities at depths less than 5.0 km are obtained by a direct inversion method of Rayleigh wave phase velocity dispersion at a period of 0.5–3.0 s. We obtain the following results. (1) The Jianshanzi fault (JSZF) is well imaged at a depth of 5.0 km. Because ore-forming fluids and materials originated from adjacent concealed granite intrusions characterized by low-velocity anomalies, we infer that the JSZF contributed to mineralization. (2) The Baiyun gold alteration belt in the northern ore field has a high velocity and cuts through the surrounding low-velocity area, extending downward to approximately 0.9 km. This high-velocity belt may be a superposition of the marble of the Dashiqiao Formation and mineralization-alteration, which suggests that the depth of the belt may be of favorable prospecting potential. (3) Based on the obvious low-velocity intrusive anomalies beneath the southern Xiaotongjiapuzi gold belt, we deduce that the mineralization of the Xiaotongjiapuzi gold belt is controlled by unexposed granite intrusions and thus has high mineralization potential at great depths. (4) A geologically reasonable model of the distribution of possible concealed granite intrusions related to deep mineralization and two prospective mineralization areas is presented.



中文翻译:

利用环境噪声层析成像技术对辽东半岛青城子矿田的浅层地壳速度结构进行短周期致密成像

位于辽东半岛中部的青城子矿田由于中生代构造和岩浆热液活动而具有大量的金,银和铅锌矿床。为了揭示浅层地壳速度与金矿化之间的关系并提供对深部矿石找矿的限制(> 1.5 km),采用了由实验短周期密集阵列和研究区域周围的334台地震仪组成的环境噪声层析成像技术。深度小于5.0 km的浅层地壳速度是通过瑞利波相速度色散的直接反演方法获得的,周期为0.5–3.0 s。我们获得以下结果。(1)剑山子断层(JSZF)在5.0 km的深度成像良好。由于成矿流体和材料源自相邻的隐伏花岗岩,其特征是低速异常,因此我们推断JSZF有助于矿化。(2)北部矿区的白云金蚀变带速度高,切穿周围的低速区,向下延伸至约0.9 km。该高速带可能是大石桥组大理石与成矿-蚀变的叠加,这表明该带的深度可能具有良好的找矿潜力。(3)基于小同家铺子金矿带南部明显的低速侵入异常,我们推断小同家铺子金矿带的矿化受未暴露的花岗岩侵入控制,因此在深部具有很高的成矿潜力。

更新日期:2021-05-27
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