3-D Mohr circle analysis of vein opening, Indarama lode-gold deposit, Zimbabwe: implications for exploration
3-D Mohr circle analysis of vein opening, Indarama lode-gold deposit, Zimbabwe: implications for exploration
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DOI：
10.1016/j.jsg.2003.11.001
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发表时间：
2004-06
影响因子：
3.1
通讯作者：
C.J McKeagney;C.A Boulter;R. Jolly;R.P Foster
中科院分区：
文献类型：
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作者：
C.J McKeagney;C.A Boulter;R. Jolly;R.P Foster
Indarama 矿脉金矿床位于津巴布韦晚太古代中部绿岩带的垂直倾斜玄武岩中。 2.68 和 2.58Ga 处的主要变形事件形成了复杂的裂缝阵列。该裂缝网络的有限方向范围在较新的变形事件结束时打开，形成了一种矿脉模式，其中 92% 的矿化脉倾角小于 50°，主要向东和西，并且代表了大多数走向方向。石英-碳酸盐岩脉极点的聚集分布表明矿脉张开时存在收缩应力场，其中 σ1 和 σ2 接近水平（分别指向 NNW-SSE 和 ENE-WSW），而 σ3 接近垂直。 3维莫尔圆分析表明，σ2约为σ1（应力比）的67%，驱动压力比（R'）约为0.4，反映了流体压力、平均应力和最大剪应力在裂缝张开控制条件中的作用。
The Indarama lode gold deposit is hosted by vertically-dipping basalt in the Late Archaean Midlands Greenstone Belt of Zimbabwe. Major deformation events at 2.68 and 2.58Ga established a complex array of fractures. A limited range of orientations of this fracture network opened towards the end of the younger deformation event, creating a lode pattern where 92% of mineralised veins dip at less than 50°, mainly to the E and W, and most strike directions are represented. A clustered distribution of poles to the quartz–carbonate veins indicates a constrictional stress field at the time of vein opening where σ1and σ2were near horizontal, (directed NNW–SSE and ENE–WSW, respectively), and σ3was near vertical. 3-D Mohr circle analysis demonstrates that σ2was approximately 67% of σ1(the stress ratio) and that the driving pressure ratio (R′) was approximately 0.4, reflecting the role of fluid pressure, mean stress, and the maximum shear stress in controlling conditions of fracture opening.