溧水爱景山超大型锶矿控矿断裂构造性质及转换机制

The Nature Transformation and Formation Mechanism of the Ore-Controlling Fault Structures in Aijingshan Super Large-Scale Strontium Deposit of Lishui

摘要: 溧水爱景山锶矿是溧水火山岩盆地唯一在采的锶矿床，目前已形成7个采矿中段。矿区内，F₂断裂控制了矿体的下盘边界，而F₇断裂则控制了矿体的上盘边界。F₂和F₇断裂构造具有先张性后压性的特征，但构造性质转变的具体位置尚未准确厘定，一定程度上影响了开拓工程的布置和采矿效率。本文调查了爱景山锶矿在采7个采矿中段能够观察到的F₂和F₇断裂构造所在位置、形态，分析了构造性质。地表北部，F₂断裂构造表现为张性特征，而南部表现为压性特征；−150 m中段北部表现为张性，而南部已由张性转换成压性；−190 m中段及向下深部均为压性特征。地表F7断裂构造为张性，但在−230 m中段及以深已成为压性，并且可以一直向北部延伸。分析了断裂构造由张性向压性转换的形成机制，举例阐述了构造性质转变过程中派生的构造对找矿勘探的实际影响。本文的认识可为溧水火山岩盆地内构造演化作用研究提供参考，也为矿山深部找矿预测提供依据。

Abstract: Aijingshan strontium deposit in Lishui is the only mining strontium deposit in the Volcanic Basin of Lishui and has formed seven mining middle sections now. In the mining area, the F₂ fault controls the lower boundary of the ore body, while the F₇ fault does the upper boundary of the ore body. The F₂ and F₇ fault structures have the characteristic of tension in the early stage and then compression in the late stage, but the specific location of the structural property transformation has not been accurately determined, which to some extent affects the layout of development projects and mining efficiency. The location and morphology of the F₂ and F₇ fault structures that can be observed in seven mining sections of Aijingshan strontium deposit are investigated, their properties are studied in the paper. The F₂ fault exhibits tensional characteristics in the north and compressive characteristics in the south of the earth’s surface. At −150 m mining middle section, F₂ exhibits tension in the northern region, while in the southern region, it has transitioned from tension to compression. At −190 m mining middle section and deeper, F₂ is all characterized by compression. The F₇ fault is tensile in the earth’s surface, but it has become compressive at −230 m mining middle section and it can extend northward. The formation mechanism of fault structures transitioning from tension to compression is also analyzed. The practical impact of structures derived from the transformation of structural properties on the prospecting prediction are stated by the examples. The understanding in this article could provide a reference for the study of tectonic evolution in the Volcanic Basin of Lishui, and also provide a basis for deep prospecting prediction in the strontium deposit.